From 633d50eb3f8f6160a9def7f77b55a8b3cbb38b40 Mon Sep 17 00:00:00 2001
From: athenian200 <athenian200@outlook.com>
Date: Fri, 23 Oct 2020 14:34:55 -0500
Subject: [PATCH 01/30] Issue #1673 - Part 1: Allow tab-size to accept
 <length>.

Currently -moz-tab-size only accepts <number> values, and both Chrome and Firefox currently support <length> values and have for some time now. So with this you would be able to support sizes in px or em, for instance. This was implemented in Firefox 53 and was trivial to backport.
---
 layout/generic/nsTextFrame.cpp         | 74 ++++++++++++--------
 layout/style/nsCSSPropList.h           |  2 +-
 layout/style/nsComputedDOMStyle.cpp    |  2 +-
 layout/style/nsRuleNode.cpp            | 96 +++++++++++++++++++-------
 layout/style/nsStyleStruct.cpp         |  4 +-
 layout/style/nsStyleStruct.h           |  2 +-
 layout/style/test/property_database.js |  6 +-
 7 files changed, 124 insertions(+), 62 deletions(-)

diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index 4decdc8ec9..663002ba13 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -3176,7 +3176,7 @@ public:
     return mFontMetrics;
   }
 
-  void CalcTabWidths(Range aTransformedRange);
+  void CalcTabWidths(Range aTransformedRange, gfxFloat aTabWidth);
 
   const gfxSkipCharsIterator& GetEndHint() { return mTempIterator; }
 
@@ -3362,6 +3362,28 @@ CanAddSpacingAfter(const gfxTextRun* aTextRun, uint32_t aOffset)
     aTextRun->IsLigatureGroupStart(aOffset + 1);
 }
 
+static gfxFloat
+ComputeTabWidthAppUnits(nsIFrame* aFrame, gfxTextRun* aTextRun)
+{
+  const nsStyleText* textStyle = aFrame->StyleText();
+  if (textStyle->mTabSize.GetUnit() != eStyleUnit_Factor) {
+    nscoord w = textStyle->mTabSize.GetCoordValue();
+    MOZ_ASSERT(w >= 0);
+    return w;
+  }
+
+  gfxFloat spaces = textStyle->mTabSize.GetFactorValue();
+  MOZ_ASSERT(spaces >= 0);
+
+  // Round the space width when converting to appunits the same way
+  // textruns do.
+  gfxFloat spaceWidthAppUnits =
+    NS_round(GetFirstFontMetrics(aTextRun->GetFontGroup(),
+                                 aTextRun->IsVertical()).spaceWidth *
+             aTextRun->GetAppUnitsPerDevUnit());
+  return spaces * spaceWidthAppUnits;
+}
+
 void
 PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
                                      bool aIgnoreTabs)
@@ -3409,17 +3431,16 @@ PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
     }
   }
 
-  // Ignore tab spacing rather than computing it, if the tab size is 0
-  if (!aIgnoreTabs)
-    aIgnoreTabs = mFrame->StyleText()->mTabSize == 0;
-
   // Now add tab spacing, if there is any
   if (!aIgnoreTabs) {
-    CalcTabWidths(aRange);
-    if (mTabWidths) {
-      mTabWidths->ApplySpacing(aSpacing,
-                               aRange.start - mStart.GetSkippedOffset(),
-                               aRange.Length());
+    gfxFloat tabWidth = ComputeTabWidthAppUnits(mFrame, mTextRun);
+    if (tabWidth > 0) {
+      CalcTabWidths(aRange);
+      if (mTabWidths) {
+        mTabWidths->ApplySpacing(aSpacing,
+                                 aRange.start - mStart.GetSkippedOffset(),
+                                 aRange.Length());
+      }
     }
   }
 
@@ -3442,33 +3463,23 @@ PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
   }
 }
 
-static gfxFloat
-ComputeTabWidthAppUnits(nsIFrame* aFrame, const gfxTextRun* aTextRun)
-{
-  // Get the number of spaces from CSS -moz-tab-size
-  const nsStyleText* textStyle = aFrame->StyleText();
-
-  return textStyle->mTabSize * GetSpaceWidthAppUnits(aTextRun);
-}
-
 // aX and the result are in whole appunits.
 static gfxFloat
 AdvanceToNextTab(gfxFloat aX, nsIFrame* aFrame,
-                 const gfxTextRun* aTextRun, gfxFloat* aCachedTabWidth)
+                 gfxTextRun* aTextRun, gfxFloat* aTabWidth)
 {
-  if (*aCachedTabWidth < 0) {
-    *aCachedTabWidth = ComputeTabWidthAppUnits(aFrame, aTextRun);
-  }
 
   // Advance aX to the next multiple of *aCachedTabWidth. We must advance
   // by at least 1 appunit.
   // XXX should we make this 1 CSS pixel?
-  return ceil((aX + 1)/(*aCachedTabWidth))*(*aCachedTabWidth);
+  return ceil((aX + 1)/ aTabWidth) * aTabWidth;
 }
 
 void
-PropertyProvider::CalcTabWidths(Range aRange)
+PropertyProvider::CalcTabWidths(Range aRange, gfxFloat aTabWidth)
 {
+  MOZ_ASSERT(aTabWidth > 0);
+
   if (!mTabWidths) {
     if (mReflowing && !mLineContainer) {
       // Intrinsic width computation does its own tab processing. We
@@ -3503,7 +3514,6 @@ PropertyProvider::CalcTabWidths(Range aRange)
     NS_ASSERTION(mReflowing,
                  "We need precomputed tab widths, but don't have enough.");
 
-    gfxFloat tabWidth = -1;
     for (uint32_t i = tabsEnd; i < aRange.end; ++i) {
       Spacing spacing;
       GetSpacingInternal(Range(i, i + 1), &spacing, true);
@@ -3525,7 +3535,7 @@ PropertyProvider::CalcTabWidths(Range aRange)
           mFrame->SetProperty(TabWidthProperty(), mTabWidths);
         }
         double nextTab = AdvanceToNextTab(mOffsetFromBlockOriginForTabs,
-                mFrame, mTextRun, &tabWidth);
+                mFrame, mTextRun, aTabWidth);
         mTabWidths->mWidths.AppendElement(TabWidth(i - startOffset, 
                 NSToIntRound(nextTab - mOffsetFromBlockOriginForTabs)));
         mOffsetFromBlockOriginForTabs = nextTab;
@@ -8319,9 +8329,12 @@ nsTextFrame::AddInlineMinISizeForFlow(nsRenderingContext *aRenderingContext,
       PropertyProvider::Spacing spacing;
       provider.GetSpacing(Range(i, i + 1), &spacing);
       aData->mCurrentLine += nscoord(spacing.mBefore);
+      if (tabWidth < 0) {
+	tabWidth = ComputeTabWidthAppUnits(this, textRun);
+      }
       gfxFloat afterTab =
         AdvanceToNextTab(aData->mCurrentLine, this,
-                         textRun, &tabWidth);
+                         textRun, tabWidth);
       aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
       wordStart = i + 1;
     } else if (i < flowEndInTextRun ||
@@ -8478,9 +8491,12 @@ nsTextFrame::AddInlinePrefISizeForFlow(nsRenderingContext *aRenderingContext,
       PropertyProvider::Spacing spacing;
       provider.GetSpacing(Range(i, i + 1), &spacing);
       aData->mCurrentLine += nscoord(spacing.mBefore);
+      if (tabWidth < 0) {
+	tabWidth = ComputeTabWidthAppUnits(this, textRun);
+      }
       gfxFloat afterTab =
         AdvanceToNextTab(aData->mCurrentLine, this,
-                         textRun, &tabWidth);
+                         textRun, tabWidth);
       aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
       lineStart = i + 1;
     } else if (preformattedNewline) {
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 4f79db5a55..5c5cfcda1c 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -3885,7 +3885,7 @@ CSS_PROP_TEXT(
     CSS_PROPERTY_PARSE_VALUE |
         CSS_PROPERTY_VALUE_NONNEGATIVE,
     "",
-    VARIANT_HI,
+    VARIANT_INHERIT | VARIANT_LNCALC,
     nullptr,
     offsetof(nsStyleText, mTabSize),
     eStyleAnimType_Discrete)
diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index 080932af23..748f990b77 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -4013,7 +4013,7 @@ already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetTabSize()
 {
   RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
-  val->SetNumber(StyleText()->mTabSize);
+  SetValueToCoord(val, StyleText()->mTabSize, true);
   return val.forget();
 }
 
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index c32369e9bb..e41857db76 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -4507,20 +4507,20 @@ TruncateStringToSingleGrapheme(nsAString& aStr)
   }
 }
 
-struct LineHeightCalcObj
+struct LengthNumberCalcObj
 {
-  float mLineHeight;
+  float LengthNumberCalcObj;
   bool mIsNumber;
 };
 
-struct SetLineHeightCalcOps : public css::NumbersAlreadyNormalizedOps
+struct LengthNumberCalcOps : public css::FloatCoeffsAlreadyNormalizedOps
 {
-  typedef LineHeightCalcObj result_type;
+  typedef LengthNumberCalcObj result_type;
   nsStyleContext* const mStyleContext;
   nsPresContext* const mPresContext;
   RuleNodeCacheConditions& mConditions;
 
-  SetLineHeightCalcOps(nsStyleContext* aStyleContext,
+  LengthNumberCalcOps(nsStyleContext* aStyleContext,
                        nsPresContext* aPresContext,
                        RuleNodeCacheConditions& aConditions)
     : mStyleContext(aStyleContext),
@@ -4535,15 +4535,15 @@ struct SetLineHeightCalcOps : public css::NumbersAlreadyNormalizedOps
   {
     MOZ_ASSERT(aValue1.mIsNumber == aValue2.mIsNumber);
 
-    LineHeightCalcObj result;
+    LengthNumberCalcObj result;
     result.mIsNumber = aValue1.mIsNumber;
     if (aCalcFunction == eCSSUnit_Calc_Plus) {
-      result.mLineHeight = aValue1.mLineHeight + aValue2.mLineHeight;
+      result.mValue = aValue1.mValue + aValue2.mValue;
       return result;
     }
     MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Minus,
                "unexpected unit");
-    result.mLineHeight = aValue1.mLineHeight - aValue2.mLineHeight;
+    result.mValue = aValue1.mValue - aValue2.mValue;
     return result;
   }
 
@@ -4553,9 +4553,9 @@ struct SetLineHeightCalcOps : public css::NumbersAlreadyNormalizedOps
   {
     MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Times_L,
                "unexpected unit");
-    LineHeightCalcObj result;
+    LengthNumberCalcObj result;
     result.mIsNumber = aValue2.mIsNumber;
-    result.mLineHeight = aValue1 * aValue2.mLineHeight;
+    result.mValue = aValue1 * aValue2.mValue;
     return result;
   }
 
@@ -4563,39 +4563,69 @@ struct SetLineHeightCalcOps : public css::NumbersAlreadyNormalizedOps
   MergeMultiplicativeR(nsCSSUnit aCalcFunction,
                        result_type aValue1, float aValue2)
   {
-    LineHeightCalcObj result;
+    LengthNumberCalcObj result;
     result.mIsNumber = aValue1.mIsNumber;
     if (aCalcFunction == eCSSUnit_Calc_Times_R) {
-      result.mLineHeight = aValue1.mLineHeight * aValue2;
+      result.mValue = aValue1.mValue * aValue2;
       return result;
     }
     MOZ_ASSERT(aCalcFunction == eCSSUnit_Calc_Divided,
                "unexpected unit");
-    result.mLineHeight = aValue1.mLineHeight / aValue2;
+    result.mValue = aValue1.mValue / aValue2;
     return result;
   }
 
   result_type ComputeLeafValue(const nsCSSValue& aValue)
   {
-    LineHeightCalcObj result;
+    LengthNumberCalcObj result;
     if (aValue.IsLengthUnit()) {
       result.mIsNumber = false;
-      result.mLineHeight = CalcLength(aValue, mStyleContext,
+      result.mValue = CalcLength(aValue, mStyleContext,
+                                      mPresContext, mConditions);
+    }
+    else if (eCSSUnit_Number == aValue.GetUnit()) {
+      result.mIsNumber = true;
+      result.mValue = aValue.GetFloatValue();
+    } else {
+      MOZ_ASSERT(false, "unexpected value");
+      result.mIsNumber = true;
+      result.mValue = 1.0f;
+    }
+
+    return result;
+  }
+};
+
+struct SetLineHeightCalcOps : public LengthNumberCalcOps
+{
+  SetLineHeightCalcOps(nsStyleContext* aStyleContext,
+                       nsPresContext* aPresContext,
+                       RuleNodeCacheConditions& aConditions)
+    : LengthNumberCalcOps(aStyleContext, aPresContext, aConditions)
+  {
+  }
+
+  result_type ComputeLeafValue(const nsCSSValue& aValue)
+  {
+    LengthNumberCalcObj result;
+    if (aValue.IsLengthUnit()) {
+      result.mIsNumber = false;
+      result.mValue = CalcLength(aValue, mStyleContext,
                                       mPresContext, mConditions);
     }
     else if (eCSSUnit_Percent == aValue.GetUnit()) {
       mConditions.SetUncacheable();
       result.mIsNumber = false;
       nscoord fontSize = mStyleContext->StyleFont()->mFont.size;
-      result.mLineHeight = fontSize * aValue.GetPercentValue();
+      result.mValue = fontSize * aValue.GetPercentValue();
     }
     else if (eCSSUnit_Number == aValue.GetUnit()) {
       result.mIsNumber = true;
-      result.mLineHeight = aValue.GetFloatValue();
+      result.mValue = aValue.GetFloatValue();
     } else {
       MOZ_ASSERT(false, "unexpected value");
       result.mIsNumber = true;
-      result.mLineHeight = 1.0f;
+      result.mValue = 1.0f;
     }
 
     return result;
@@ -4619,11 +4649,25 @@ nsRuleNode::ComputeTextData(void* aStartStruct,
                                    mPresContext, text->*aField, conditions);
   };
 
-  // tab-size: integer, inherit
-  SetValue(*aRuleData->ValueForTabSize(),
-           text->mTabSize, conditions,
-           SETVAL_INTEGER | SETVAL_UNSET_INHERIT, parentText->mTabSize,
-           NS_STYLE_TABSIZE_INITIAL);
+  // tab-size: number, length, calc, inherit
+  const nsCSSValue* tabSizeValue = aRuleData->ValueForTabSize();
+  if (tabSizeValue->GetUnit() == eCSSUnit_Initial) {
+    text->mTabSize = nsStyleCoord(float(NS_STYLE_TABSIZE_INITIAL), eStyleUnit_Factor);
+  } else if (eCSSUnit_Calc == tabSizeValue->GetUnit()) {
+    LengthNumberCalcOps ops(aContext, mPresContext, conditions);
+    LengthNumberCalcObj obj = css::ComputeCalc(*tabSizeValue, ops);
+    float value = obj.mValue < 0 ? 0 : obj.mValue;
+    if (obj.mIsNumber) {
+      text->mTabSize.SetFactorValue(value);
+    } else {
+      text->mTabSize.SetCoordValue(
+        NSToCoordRoundWithClamp(value));
+    }
+  } else {
+    SetCoord(*tabSizeValue, text->mTabSize, parentText->mTabSize,
+             SETCOORD_LH | SETCOORD_FACTOR | SETCOORD_UNSET_INHERIT,
+             aContext, mPresContext, conditions);
+  }
 
   // letter-spacing: normal, length, inherit
   SetCoord(*aRuleData->ValueForLetterSpacing(),
@@ -4666,12 +4710,12 @@ nsRuleNode::ComputeTextData(void* aStartStruct,
   }
   else if (eCSSUnit_Calc == lineHeightValue->GetUnit()) {
     SetLineHeightCalcOps ops(aContext, mPresContext, conditions);
-    LineHeightCalcObj obj = css::ComputeCalc(*lineHeightValue, ops);
+    LengthNumberCalcObj obj = css::ComputeCalc(*lineHeightValue, ops);
     if (obj.mIsNumber) {
-      text->mLineHeight.SetFactorValue(obj.mLineHeight);
+      text->mLineHeight.SetFactorValue(obj.mValue);
     } else {
       text->mLineHeight.SetCoordValue(
-        NSToCoordRoundWithClamp(obj.mLineHeight));
+        NSToCoordRoundWithClamp(obj.mValue));
     }
   }
   else {
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index c0ea9c256c..073cfcd5e7 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -3806,10 +3806,10 @@ nsStyleText::nsStyleText(StyleStructContext aContext)
   , mControlCharacterVisibility(nsCSSParser::ControlCharVisibilityDefault())
   , mTextEmphasisStyle(NS_STYLE_TEXT_EMPHASIS_STYLE_NONE)
   , mTextRendering(NS_STYLE_TEXT_RENDERING_AUTO)
-  , mTabSize(NS_STYLE_TABSIZE_INITIAL)
   , mTextEmphasisColor(StyleComplexColor::CurrentColor())
   , mWebkitTextFillColor(StyleComplexColor::CurrentColor())
   , mWebkitTextStrokeColor(StyleComplexColor::CurrentColor())
+  , mTabSize(float(NS_STYLE_TABSIZE_INITIAL), eStyleUnit_Factor)
   , mWordSpacing(0, nsStyleCoord::CoordConstructor)
   , mLetterSpacing(eStyleUnit_Normal)
   , mLineHeight(eStyleUnit_Normal)
@@ -3844,10 +3844,10 @@ nsStyleText::nsStyleText(const nsStyleText& aSource)
   , mTextEmphasisPosition(aSource.mTextEmphasisPosition)
   , mTextEmphasisStyle(aSource.mTextEmphasisStyle)
   , mTextRendering(aSource.mTextRendering)
-  , mTabSize(aSource.mTabSize)
   , mTextEmphasisColor(aSource.mTextEmphasisColor)
   , mWebkitTextFillColor(aSource.mWebkitTextFillColor)
   , mWebkitTextStrokeColor(aSource.mWebkitTextStrokeColor)
+  , mTabSize(aSource.mTabSize)
   , mWordSpacing(aSource.mWordSpacing)
   , mLetterSpacing(aSource.mLetterSpacing)
   , mLineHeight(aSource.mLineHeight)
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 88000c722a..831808edfd 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -2087,11 +2087,11 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleText
   uint8_t mTextEmphasisPosition;        // [inherited] see nsStyleConsts.h
   uint8_t mTextEmphasisStyle;           // [inherited] see nsStyleConsts.h
   uint8_t mTextRendering;               // [inherited] see nsStyleConsts.h
-  int32_t mTabSize;                     // [inherited] see nsStyleConsts.h
   mozilla::StyleComplexColor mTextEmphasisColor;      // [inherited]
   mozilla::StyleComplexColor mWebkitTextFillColor;    // [inherited]
   mozilla::StyleComplexColor mWebkitTextStrokeColor;  // [inherited]
 
+  nsStyleCoord mTabSize;                // [inherited] coord, factor, calc
   nsStyleCoord mWordSpacing;            // [inherited] coord, percent, calc
   nsStyleCoord mLetterSpacing;          // [inherited] coord, normal
   nsStyleCoord mLineHeight;             // [inherited] coord, factor, normal
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index d647b57161..5182dd89c1 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -2032,8 +2032,10 @@ var gCSSProperties = {
     inherited: true,
     type: CSS_TYPE_LONGHAND,
     initial_values: [ "8" ],
-    other_values: [ "0", "3", "99", "12000" ],
-    invalid_values: [ "-1", "-808", "3.0", "17.5" ]
+    other_values: [ "0", "2.5", "3", "99", "12000", "0px", "1em",
+	    "calc(1px + 1em)", "calc(1px - 2px)", "calc(1 + 1)", "calc(-2.5)" ],
+    invalid_values: [ "9%", "calc(9% + 1px)", "calc(1 + 1em)", "-1", "-808",
+	    "auto" ]
   },
   "-moz-text-size-adjust": {
     domProp: "MozTextSizeAdjust",

From b739e46f741dab18a2df37928e8adf23e9068a7a Mon Sep 17 00:00:00 2001
From: athenian200 <athenian200@outlook.com>
Date: Fri, 23 Oct 2020 19:45:52 -0500
Subject: [PATCH 02/30] Issue #1673 - Part 2: Make tab-size animatable and fix
 typos.

There were a few typos in the previous patch and this patch also makes tab-size animatable which didn't really require much of a change at all.
---
 dom/animation/test/mozilla/file_discrete-animations.html | 5 -----
 layout/generic/nsTextFrame.cpp                           | 6 +++---
 layout/style/nsCSSPropList.h                             | 2 +-
 layout/style/nsRuleNode.cpp                              | 2 +-
 layout/style/test/test_transitions_per_property.html     | 2 ++
 5 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/dom/animation/test/mozilla/file_discrete-animations.html b/dom/animation/test/mozilla/file_discrete-animations.html
index 35e818a909..eeaaa33c4e 100644
--- a/dom/animation/test/mozilla/file_discrete-animations.html
+++ b/dom/animation/test/mozilla/file_discrete-animations.html
@@ -75,11 +75,6 @@ const gMozillaSpecificProperties = {
     from: "ignore",
     to: "stretch-to-fit"
   },
-  "-moz-tab-size": {
-    // https://drafts.csswg.org/css-text-3/#propdef-tab-size
-    from: "1",
-    to: "5"
-  },
   "-moz-text-size-adjust": {
     // https://drafts.csswg.org/css-size-adjust/#propdef-text-size-adjust
     from: "none",
diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index 663002ba13..0aab2717f3 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -3435,7 +3435,7 @@ PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
   if (!aIgnoreTabs) {
     gfxFloat tabWidth = ComputeTabWidthAppUnits(mFrame, mTextRun);
     if (tabWidth > 0) {
-      CalcTabWidths(aRange);
+      CalcTabWidths(aRange, tabWidth);
       if (mTabWidths) {
         mTabWidths->ApplySpacing(aSpacing,
                                  aRange.start - mStart.GetSkippedOffset(),
@@ -3466,13 +3466,13 @@ PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
 // aX and the result are in whole appunits.
 static gfxFloat
 AdvanceToNextTab(gfxFloat aX, nsIFrame* aFrame,
-                 gfxTextRun* aTextRun, gfxFloat* aTabWidth)
+                 gfxTextRun* aTextRun, gfxFloat aTabWidth)
 {
 
   // Advance aX to the next multiple of *aCachedTabWidth. We must advance
   // by at least 1 appunit.
   // XXX should we make this 1 CSS pixel?
-  return ceil((aX + 1)/ aTabWidth) * aTabWidth;
+  return NS_round((aX + 1) / aTabWidth) * aTabWidth;
 }
 
 void
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 5c5cfcda1c..53bc845476 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -3888,7 +3888,7 @@ CSS_PROP_TEXT(
     VARIANT_INHERIT | VARIANT_LNCALC,
     nullptr,
     offsetof(nsStyleText, mTabSize),
-    eStyleAnimType_Discrete)
+    eStyleAnimType_Coord)
 CSS_PROP_TABLE(
     table-layout,
     table_layout,
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index e41857db76..6a6407e8f5 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -4509,7 +4509,7 @@ TruncateStringToSingleGrapheme(nsAString& aStr)
 
 struct LengthNumberCalcObj
 {
-  float LengthNumberCalcObj;
+  float mValue;
   bool mIsNumber;
 };
 
diff --git a/layout/style/test/test_transitions_per_property.html b/layout/style/test/test_transitions_per_property.html
index f188f4f6fb..b7659adb7d 100644
--- a/layout/style/test/test_transitions_per_property.html
+++ b/layout/style/test/test_transitions_per_property.html
@@ -248,6 +248,8 @@ var supported_properties = {
     // test_length_percent_calc_transition.
     "stroke-width": [ test_length_transition_svg, test_percent_transition,
                       test_length_clamped_svg, test_percent_clamped ],
+    "-moz-tab-size": [ test_float_zeroToOne_transition,
+                       test_float_aboveOne_transition, test_length_clamped ],
     "text-decoration": [ test_color_shorthand_transition,
                          test_true_currentcolor_shorthand_transition ],
     "text-decoration-color": [ test_color_transition,

From a64dc2a367b18f1839cbe2935bfe8860b7b84bef Mon Sep 17 00:00:00 2001
From: athenian200 <athenian200@outlook.com>
Date: Sun, 25 Oct 2020 14:27:17 -0500
Subject: [PATCH 03/30] Issue #1673 - Part 3: Bring minimum tab advance up to
 spec.

This provides a clearer rule for the minimum tab advance that brings us to alignment with the spec and both major browsers.
---
 layout/generic/nsTextFrame.cpp | 41 +++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index 0aab2717f3..07e7a36557 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -1716,6 +1716,16 @@ GetSpaceWidthAppUnits(const gfxTextRun* aTextRun)
   return spaceWidthAppUnits;
 }
 
+static gfxFloat
+GetMinTabAdvanceAppUnits(const gfxTextRun* aTextRun)
+{
+  gfxFloat chWidthAppUnits =
+    NS_round(GetFirstFontMetrics(aTextRun->GetFontGroup(),
+			         aTextRun->IsVertical()).zeroOrAveCharWidth *
+	     aTextRun->GetAppUnitsPerDevUnit());
+  return 0.5 * chWidthAppUnits;
+}
+
 static nscoord
 LetterSpacing(nsIFrame* aFrame, const nsStyleText* aStyleText = nullptr)
 {
@@ -3090,6 +3100,7 @@ public:
       mLength(aLength),
       mWordSpacing(WordSpacing(aFrame, mTextRun, aTextStyle)),
       mLetterSpacing(LetterSpacing(aFrame, aTextStyle)),
+      mMinTabAdvance(-1.0),
       mHyphenWidth(-1),
       mOffsetFromBlockOriginForTabs(aOffsetFromBlockOriginForTabs),
       mReflowing(true),
@@ -3114,6 +3125,7 @@ public:
       mLength(aFrame->GetContentLength()),
       mWordSpacing(WordSpacing(aFrame, mTextRun)),
       mLetterSpacing(LetterSpacing(aFrame)),
+      mMinTabAdvance(-1.0),
       mHyphenWidth(-1),
       mOffsetFromBlockOriginForTabs(0),
       mReflowing(false),
@@ -3178,6 +3190,13 @@ public:
 
   void CalcTabWidths(Range aTransformedRange, gfxFloat aTabWidth);
 
+  gfxFloat MinTabAdvance() {
+    if (mMinTabAdvance < 0.0) {
+      mMinTabAdvance = GetMinTabAdvanceAppUnits(mTextRun);
+    }
+    return mMinTabAdvance;
+  }
+
   const gfxSkipCharsIterator& GetEndHint() { return mTempIterator; }
 
 protected:
@@ -3210,6 +3229,7 @@ protected:
   int32_t               mLength; // DOM string length, may be INT32_MAX
   gfxFloat              mWordSpacing;     // space for each whitespace char
   gfxFloat              mLetterSpacing;   // space for each letter
+  gfxFloat		mMinTabAdvance; // min advance for <tab> char
   gfxFloat              mHyphenWidth;
   gfxFloat              mOffsetFromBlockOriginForTabs;
 
@@ -3465,14 +3485,13 @@ PropertyProvider::GetSpacingInternal(Range aRange, Spacing* aSpacing,
 
 // aX and the result are in whole appunits.
 static gfxFloat
-AdvanceToNextTab(gfxFloat aX, nsIFrame* aFrame,
-                 gfxTextRun* aTextRun, gfxFloat aTabWidth)
+AdvanceToNextTab(gfxFloat aX, nsIFrame* aFrame, gfxTextRun* aTextRun,
+	         gfxFloat aTabWidth, gfxFloat aMinAdvance)
 {
 
-  // Advance aX to the next multiple of *aCachedTabWidth. We must advance
-  // by at least 1 appunit.
-  // XXX should we make this 1 CSS pixel?
-  return NS_round((aX + 1) / aTabWidth) * aTabWidth;
+  // Advance aX to the next multiple of aTabWidth. We must advance
+  // by at least aMinAdvance.
+  return ceil((aX + aMinAdvance) / aTabWidth) * aTabWidth;
 }
 
 void
@@ -3535,7 +3554,7 @@ PropertyProvider::CalcTabWidths(Range aRange, gfxFloat aTabWidth)
           mFrame->SetProperty(TabWidthProperty(), mTabWidths);
         }
         double nextTab = AdvanceToNextTab(mOffsetFromBlockOriginForTabs,
-                mFrame, mTextRun, aTabWidth);
+	        mFrame, mTextRun, aTabWidth, MinTabAdvance());
         mTabWidths->mWidths.AppendElement(TabWidth(i - startOffset, 
                 NSToIntRound(nextTab - mOffsetFromBlockOriginForTabs)));
         mOffsetFromBlockOriginForTabs = nextTab;
@@ -8333,8 +8352,8 @@ nsTextFrame::AddInlineMinISizeForFlow(nsRenderingContext *aRenderingContext,
 	tabWidth = ComputeTabWidthAppUnits(this, textRun);
       }
       gfxFloat afterTab =
-        AdvanceToNextTab(aData->mCurrentLine, this,
-                         textRun, tabWidth);
+        AdvanceToNextTab(aData->mCurrentLine, this, textRun, tabWidth,
+			 provider.MinTabAdvance());
       aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
       wordStart = i + 1;
     } else if (i < flowEndInTextRun ||
@@ -8495,8 +8514,8 @@ nsTextFrame::AddInlinePrefISizeForFlow(nsRenderingContext *aRenderingContext,
 	tabWidth = ComputeTabWidthAppUnits(this, textRun);
       }
       gfxFloat afterTab =
-        AdvanceToNextTab(aData->mCurrentLine, this,
-                         textRun, tabWidth);
+        AdvanceToNextTab(aData->mCurrentLine, this, textRun, tabWidth,
+			 provider.MinTabAdvance());
       aData->mCurrentLine = nscoord(afterTab + spacing.mAfter);
       lineStart = i + 1;
     } else if (preformattedNewline) {

From 7373069560500839dc8acd3e4737494e4b103a56 Mon Sep 17 00:00:00 2001
From: athenian200 <athenian200@outlook.com>
Date: Tue, 27 Oct 2020 20:37:50 -0500
Subject: [PATCH 04/30] Issue #1673 - Part 4: Unprefix -moz-tab-size.

While we do fail a couple of tests, the other mainstream browsers also fail them and I think our implementation of tab-size is good enough to be unprefixed at this point. Having this patch also makes testing easier.
---
 .../shared/css/generated/properties-db.js     | 21 +++++++++++++++++--
 layout/style/nsCSSPropAliasList.h             |  4 ++++
 layout/style/nsCSSPropList.h                  |  6 +++---
 layout/style/nsComputedDOMStylePropertyList.h |  2 +-
 layout/style/nsRuleNode.cpp                   |  2 +-
 layout/style/test/property_database.js        | 11 ++++++++--
 parser/html/nsHtml5ViewSourceUtils.cpp        |  2 +-
 7 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/devtools/shared/css/generated/properties-db.js b/devtools/shared/css/generated/properties-db.js
index 01358a033d..d149995d9e 100644
--- a/devtools/shared/css/generated/properties-db.js
+++ b/devtools/shared/css/generated/properties-db.js
@@ -1233,7 +1233,7 @@ exports.CSS_PROPERTIES = {
   "-moz-tab-size": {
     "isInherited": true,
     "subproperties": [
-      "-moz-tab-size"
+      "tab-size"
     ],
     "supports": [
       7
@@ -3052,7 +3052,7 @@ exports.CSS_PROPERTIES = {
       "stroke-opacity",
       "stroke-width",
       "-x-system-font",
-      "-moz-tab-size",
+      "tab-size",
       "table-layout",
       "text-align",
       "text-align-last",
@@ -8650,6 +8650,23 @@ exports.CSS_PROPERTIES = {
       "unset"
     ]
   },
+  "tab-size": {
+    "isInherited": true,
+    "subproperties": [
+      "tab-size"
+    ],
+    "supports": [
+      6,
+      7
+    ],
+    "values": [
+      "-moz-calc",
+      "calc",
+      "inherit",
+      "initial",
+      "unset"
+    ]
+  },
   "table-layout": {
     "isInherited": false,
     "subproperties": [
diff --git a/layout/style/nsCSSPropAliasList.h b/layout/style/nsCSSPropAliasList.h
index 7025a25b5c..4f2a6e6b6d 100644
--- a/layout/style/nsCSSPropAliasList.h
+++ b/layout/style/nsCSSPropAliasList.h
@@ -222,6 +222,10 @@ CSS_PROP_ALIAS(-moz-columns,
                columns,
                MozColumns,
                "")
+CSS_PROP_ALIAS(-moz-tab-size,
+	       tab_size,
+	       MozTabSize,
+	       "")
 
 #define WEBKIT_PREFIX_PREF "layout.css.prefixes.webkit"
 
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 53bc845476..658ea68d7a 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -3879,9 +3879,9 @@ CSS_PROP_FONT(
     eStyleAnimType_None)
 #endif // CSS_PROP_LIST_EXCLUDE_INTERNAL
 CSS_PROP_TEXT(
-    -moz-tab-size,
-    _moz_tab_size,
-    CSS_PROP_DOMPROP_PREFIXED(TabSize),
+    tab-size,
+    tab_size,
+    TabSize,
     CSS_PROPERTY_PARSE_VALUE |
         CSS_PROPERTY_VALUE_NONNEGATIVE,
     "",
diff --git a/layout/style/nsComputedDOMStylePropertyList.h b/layout/style/nsComputedDOMStylePropertyList.h
index 8d4d8e45e2..6a18a7ad0a 100644
--- a/layout/style/nsComputedDOMStylePropertyList.h
+++ b/layout/style/nsComputedDOMStylePropertyList.h
@@ -228,6 +228,7 @@ COMPUTED_STYLE_PROP(scroll_snap_type_x,            ScrollSnapTypeX)
 COMPUTED_STYLE_PROP(scroll_snap_type_y,            ScrollSnapTypeY)
 COMPUTED_STYLE_PROP(shape_outside,                 ShapeOutside)
 //// COMPUTED_STYLE_PROP(size,                     Size)
+COMPUTED_STYLE_PROP(tab_size,			   TabSize)
 COMPUTED_STYLE_PROP(table_layout,                  TableLayout)
 COMPUTED_STYLE_PROP(text_align,                    TextAlign)
 COMPUTED_STYLE_PROP(text_align_last,               TextAlignLast)
@@ -295,7 +296,6 @@ COMPUTED_STYLE_PROP(_moz_outline_radius_bottomRight,OutlineRadiusBottomRight)
 COMPUTED_STYLE_PROP(_moz_outline_radius_topLeft,    OutlineRadiusTopLeft)
 COMPUTED_STYLE_PROP(_moz_outline_radius_topRight,   OutlineRadiusTopRight)
 COMPUTED_STYLE_PROP(stack_sizing,                  StackSizing)
-COMPUTED_STYLE_PROP(_moz_tab_size,                 TabSize)
 COMPUTED_STYLE_PROP(text_size_adjust,              TextSizeAdjust)
 COMPUTED_STYLE_PROP(user_focus,                    UserFocus)
 COMPUTED_STYLE_PROP(user_input,                    UserInput)
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 6a6407e8f5..ffde071d6a 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -4513,7 +4513,7 @@ struct LengthNumberCalcObj
   bool mIsNumber;
 };
 
-struct LengthNumberCalcOps : public css::FloatCoeffsAlreadyNormalizedOps
+struct LengthNumberCalcOps : public css::NumbersAlreadyNormalizedOps
 {
   typedef LengthNumberCalcObj result_type;
   nsStyleContext* const mStyleContext;
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index 5182dd89c1..635431e8fb 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -2027,8 +2027,8 @@ var gCSSProperties = {
     other_values: [ "ignore" ],
     invalid_values: []
   },
-  "-moz-tab-size": {
-    domProp: "MozTabSize",
+  "tab-size": {
+    domProp: "TabSize",
     inherited: true,
     type: CSS_TYPE_LONGHAND,
     initial_values: [ "8" ],
@@ -2037,6 +2037,13 @@ var gCSSProperties = {
     invalid_values: [ "9%", "calc(9% + 1px)", "calc(1 + 1em)", "-1", "-808",
 	    "auto" ]
   },
+  "-moz-tab-size": {
+    domProp: "MozTabSize",
+    inherited: true,
+    type: CSS_TYPE_SHORTHAND_AND_LONGHAND
+    alias_for: "tab-size",
+    subproperties: [ "tab-size" ]
+  },
   "-moz-text-size-adjust": {
     domProp: "MozTextSizeAdjust",
     inherited: true,
diff --git a/parser/html/nsHtml5ViewSourceUtils.cpp b/parser/html/nsHtml5ViewSourceUtils.cpp
index b2f635bffe..910a6691e2 100644
--- a/parser/html/nsHtml5ViewSourceUtils.cpp
+++ b/parser/html/nsHtml5ViewSourceUtils.cpp
@@ -31,7 +31,7 @@ nsHtml5ViewSourceUtils::NewBodyAttributes()
   int32_t tabSize = mozilla::Preferences::GetInt("view_source.tab_size", 4);
   if (tabSize > 0) {
     nsString style;
-    style.AssignASCII("-moz-tab-size: ");
+    style.AssignASCII("tab-size: ");
     style.AppendInt(tabSize);
     bodyAttrs->addAttribute(
       nsHtml5AttributeName::ATTR_STYLE, nsHtml5String::FromString(style), -1);

From 5026bdf5eebfdaed6a001c81a11389a421cc8cce Mon Sep 17 00:00:00 2001
From: athenian200 <athenian200@outlook.com>
Date: Wed, 28 Oct 2020 22:57:34 -0500
Subject: [PATCH 05/30] Issue #1673 - Part 5: Fix brace style and missed
 -moz-tab-size reference.

---
 layout/style/nsRuleNode.cpp                   | 465 ++++++++----------
 .../test/test_transitions_per_property.html   |   2 +-
 2 files changed, 212 insertions(+), 255 deletions(-)

diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index ffde071d6a..9721b4bed6 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -869,8 +869,7 @@ static bool SetCoord(const nsCSSValue& aValue, nsStyleCoord& aCoord,
   bool result = true;
   if (aValue.GetUnit() == eCSSUnit_Null) {
     result = false;
-  }
-  else if ((((aMask & SETCOORD_LENGTH) != 0) &&
+  } else if ((((aMask & SETCOORD_LENGTH) != 0) &&
             aValue.IsLengthUnit()) ||
            (((aMask & SETCOORD_CALC_LENGTH_ONLY) != 0) &&
             aValue.IsCalcUnit())) {
@@ -882,83 +881,63 @@ static bool SetCoord(const nsCSSValue& aValue, nsStyleCoord& aCoord,
       len = 0;
     }
     aCoord.SetCoordValue(len);
-  }
-  else if (((aMask & SETCOORD_PERCENT) != 0) &&
+  } else if (((aMask & SETCOORD_PERCENT) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Percent)) {
     aCoord.SetPercentValue(aValue.GetPercentValue());
-  }
-  else if (((aMask & SETCOORD_INTEGER) != 0) &&
+  } else if (((aMask & SETCOORD_INTEGER) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Integer)) {
     aCoord.SetIntValue(aValue.GetIntValue(), eStyleUnit_Integer);
-  }
-  else if (((aMask & SETCOORD_ENUMERATED) != 0) &&
+  } else if (((aMask & SETCOORD_ENUMERATED) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Enumerated)) {
     aCoord.SetIntValue(aValue.GetIntValue(), eStyleUnit_Enumerated);
-  }
-  else if (((aMask & SETCOORD_BOX_POSITION) != 0) &&
+  } else if (((aMask & SETCOORD_BOX_POSITION) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Enumerated)) {
     aCoord.SetPercentValue(GetFloatFromBoxPosition(aValue.GetIntValue()));
-  }
-  else if (((aMask & SETCOORD_AUTO) != 0) &&
+  } else if (((aMask & SETCOORD_AUTO) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Auto)) {
     aCoord.SetAutoValue();
-  }
-  else if ((((aMask & SETCOORD_INHERIT) != 0) &&
+  } else if ((((aMask & SETCOORD_INHERIT) != 0) &&
             aValue.GetUnit() == eCSSUnit_Inherit) ||
            (((aMask & SETCOORD_UNSET_INHERIT) != 0) &&
             aValue.GetUnit() == eCSSUnit_Unset)) {
     aCoord = aParentCoord;  // just inherit value from parent
     aConditions.SetUncacheable();
-  }
-  else if (((aMask & SETCOORD_NORMAL) != 0) &&
+  } else if (((aMask & SETCOORD_NORMAL) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Normal)) {
     aCoord.SetNormalValue();
-  }
-  else if (((aMask & SETCOORD_NONE) != 0) &&
+  } else if (((aMask & SETCOORD_NONE) != 0) &&
            (aValue.GetUnit() == eCSSUnit_None)) {
     aCoord.SetNoneValue();
-  }
-  else if (((aMask & SETCOORD_FACTOR) != 0) &&
+  } else if (((aMask & SETCOORD_FACTOR) != 0) &&
            (aValue.GetUnit() == eCSSUnit_Number)) {
     aCoord.SetFactorValue(aValue.GetFloatValue());
-  }
-  else if (((aMask & SETCOORD_STORE_CALC) != 0) &&
+  } else if (((aMask & SETCOORD_STORE_CALC) != 0) &&
            (aValue.IsCalcUnit())) {
     SpecifiedCalcToComputedCalc(aValue, aCoord, aStyleContext,
                                 aConditions);
-  }
-  else if (aValue.GetUnit() == eCSSUnit_Initial ||
+  } else if (aValue.GetUnit() == eCSSUnit_Initial ||
            (aValue.GetUnit() == eCSSUnit_Unset &&
             ((aMask & SETCOORD_UNSET_INITIAL) != 0))) {
     if ((aMask & SETCOORD_INITIAL_AUTO) != 0) {
       aCoord.SetAutoValue();
-    }
-    else if ((aMask & SETCOORD_INITIAL_ZERO) != 0) {
+    } else if ((aMask & SETCOORD_INITIAL_ZERO) != 0) {
       aCoord.SetCoordValue(0);
-    }
-    else if ((aMask & SETCOORD_INITIAL_FACTOR_ZERO) != 0) {
+    } else if ((aMask & SETCOORD_INITIAL_FACTOR_ZERO) != 0) {
       aCoord.SetFactorValue(0.0f);
-    }
-    else if ((aMask & SETCOORD_INITIAL_NONE) != 0) {
+    } else if ((aMask & SETCOORD_INITIAL_NONE) != 0) {
       aCoord.SetNoneValue();
-    }
-    else if ((aMask & SETCOORD_INITIAL_NORMAL) != 0) {
+    } else if ((aMask & SETCOORD_INITIAL_NORMAL) != 0) {
       aCoord.SetNormalValue();
-    }
-    else if ((aMask & SETCOORD_INITIAL_HALF) != 0) {
+    } else if ((aMask & SETCOORD_INITIAL_HALF) != 0) {
       aCoord.SetPercentValue(0.5f);
-    }
-    else if ((aMask & SETCOORD_INITIAL_HUNDRED_PCT) != 0) {
+    } else if ((aMask & SETCOORD_INITIAL_HUNDRED_PCT) != 0) {
       aCoord.SetPercentValue(1.0f);
-    }
-    else if ((aMask & SETCOORD_INITIAL_FACTOR_ONE) != 0) {
+    } else if ((aMask & SETCOORD_INITIAL_FACTOR_ONE) != 0) {
       aCoord.SetFactorValue(1.0f);
-    }
-    else {
+    } else {
       result = false;  // didn't set anything
     }
-  }
-  else if ((aMask & SETCOORD_ANGLE) != 0 &&
+  } else if ((aMask & SETCOORD_ANGLE) != 0 &&
            (aValue.IsAngularUnit())) {
     nsStyleUnit unit;
     switch (aValue.GetUnit()) {
@@ -1037,8 +1016,7 @@ static bool SetColor(const nsCSSValue& aValue, const nscolor aParentColor,
   if (aValue.IsNumericColorUnit()) {
     aResult = aValue.GetColorValue();
     result = true;
-  }
-  else if (eCSSUnit_Ident == unit) {
+  } else if (eCSSUnit_Ident == unit) {
     nsAutoString  value;
     aValue.GetStringValue(value);
     nscolor rgba;
@@ -1046,8 +1024,7 @@ static bool SetColor(const nsCSSValue& aValue, const nscolor aParentColor,
       aResult = rgba;
       result = true;
     }
-  }
-  else if (eCSSUnit_EnumColor == unit) {
+  } else if (eCSSUnit_EnumColor == unit) {
     int32_t intValue = aValue.GetIntValue();
     if (0 <= intValue) {
       LookAndFeel::ColorID colorID = (LookAndFeel::ColorID) intValue;
@@ -1106,13 +1083,11 @@ static bool SetColor(const nsCSSValue& aValue, const nscolor aParentColor,
           break;
       }
     }
-  }
-  else if (eCSSUnit_Inherit == unit) {
+  } else if (eCSSUnit_Inherit == unit) {
     aResult = aParentColor;
     result = true;
     aConditions.SetUncacheable();
-  }
-  else if (eCSSUnit_Enumerated == unit &&
+  } else if (eCSSUnit_Enumerated == unit &&
            aValue.GetIntValue() == NS_STYLE_COLOR_INHERIT_FROM_BODY) {
     NS_ASSERTION(aPresContext->CompatibilityMode() == eCompatibility_NavQuirks,
                  "Should only get this value in quirks mode");
@@ -1585,14 +1560,17 @@ SetFactor(const nsCSSValue& aValue, float& aField, RuleNodeCacheConditions& aCon
     aField = aValue.GetFloatValue();
     if (aFlags & SETFCT_POSITIVE) {
       NS_ASSERTION(aField >= 0.0f, "negative value for positive-only property");
-      if (aField < 0.0f)
+      if (aField < 0.0f) {
         aField = 0.0f;
-    }
+      }
+    } 
     if (aFlags & SETFCT_OPACITY) {
-      if (aField < 0.0f)
+      if (aField < 0.0f) {
         aField = 0.0f;
-      if (aField > 1.0f)
+      }
+      if (aField > 1.0f) {
         aField = 1.0f;
+      }
     }
     return;
 
@@ -1726,10 +1704,11 @@ nsRuleNode::Transition(nsIStyleRule* aRule, SheetType aLevel,
       curr = curr->mNextSibling;
       ++numKids;
     }
-    if (curr)
+    if (curr) {
       next = curr;
-    else if (numKids >= kMaxChildrenInList)
+    } else if (numKids >= kMaxChildrenInList) {
       ConvertChildrenToHash(numKids);
+    }
   }
 
   if (ChildrenAreHashed()) {
@@ -1739,9 +1718,9 @@ nsRuleNode::Transition(nsIStyleRule* aRule, SheetType aLevel,
       NS_WARNING("out of memory");
       return this;
     }
-    if (entry->mRuleNode)
+    if (entry->mRuleNode) {
       next = entry->mRuleNode;
-    else {
+    } else {
       next = entry->mRuleNode = new (mPresContext)
         nsRuleNode(mPresContext, this, aRule, aLevel, aIsImportantRule);
     }
@@ -1960,10 +1939,11 @@ CheckFontCallback(const nsRuleData* aRuleData,
     // Promote reset to mixed since we have something that depends on
     // the parent.  But never promote to inherited since that could
     // cause inheritance of the exact value.
-    if (aResult == nsRuleNode::eRulePartialReset)
+    if (aResult == nsRuleNode::eRulePartialReset) {
       aResult = nsRuleNode::eRulePartialMixed;
-    else if (aResult == nsRuleNode::eRuleFullReset)
+    } else if (aResult == nsRuleNode::eRuleFullReset) {
       aResult = nsRuleNode::eRuleFullMixed;
+    }
   }
 
   return aResult;
@@ -1996,10 +1976,11 @@ CheckTextCallback(const nsRuleData* aRuleData,
        textAlignValue->GetIntValue() == NS_STYLE_TEXT_ALIGN_MATCH_PARENT)) {
     // Promote reset to mixed since we have something that depends on
     // the parent.
-    if (aResult == nsRuleNode::eRulePartialReset)
+    if (aResult == nsRuleNode::eRulePartialReset) {
       aResult = nsRuleNode::eRulePartialMixed;
-    else if (aResult == nsRuleNode::eRuleFullReset)
+    } else if (aResult == nsRuleNode::eRuleFullReset) {
       aResult = nsRuleNode::eRuleFullMixed;
+    }
   }
 
   return aResult;
@@ -2250,9 +2231,9 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
    * optimize based on the edge cases and not the in-between cases.
    */
   nsRuleNode::RuleDetail result;
-  if (inherited == total)
+  if (inherited == total) {
     result = eRuleFullInherited;
-  else if (specified == total
+  } else if (specified == total
            // MathML defines 5 properties in Font that will never be set when
            // MathML is not in use. Therefore if all but five
            // properties have been set, and MathML is not enabled, we can treat
@@ -2262,18 +2243,21 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
            || (aSID == eStyleStruct_Font && specified + 5 == total &&
                !mPresContext->Document()->GetMathMLEnabled())
           ) {
-    if (inherited == 0)
+    if (inherited == 0) {
       result = eRuleFullReset;
-    else
+    } else {
       result = eRuleFullMixed;
-  } else if (specified == 0)
+    }
+
+  } else if (specified == 0) {
     result = eRuleNone;
-  else if (specified == inherited)
+  } else if (specified == inherited) {
     result = eRulePartialInherited;
-  else if (inherited == 0)
+  } else if (inherited == 0) {
     result = eRulePartialReset;
-  else
+  } else {
     result = eRulePartialMixed;
+  }
 
   CheckCallbackFn cb = gCheckCallbacks[aSID];
   if (cb) {
@@ -2320,8 +2304,9 @@ UnsetPropertiesWithoutFlags(const nsStyleStructID aSID,
 
   for (size_t i = 0, i_end = nsCSSProps::PropertyCountInStruct(aSID);
        i != i_end; ++i) {
-    if ((flagData[i] & aFlags) != aFlags)
+    if ((flagData[i] & aFlags) != aFlags) {
       values[i].Reset();
+    }
   }
 }
 
@@ -2451,8 +2436,9 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
   while (ruleNode) {
     // See if this rule node has cached the fact that the remaining
     // nodes along this path specify no data whatsoever.
-    if (ruleNode->mNoneBits & bit)
+    if (ruleNode->mNoneBits & bit) {
       break;
+    }
 
     // If the dependent bit is set on a rule node for this struct, that
     // means its rule won't have any information to add, so skip it.
@@ -2471,9 +2457,9 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
     // Check for cached data after the inner loop above -- otherwise
     // we'll miss it.
     startStruct = ruleNode->mStyleData.GetStyleData(aSID);
-    if (startStruct)
+    if (startStruct) {
       break; // We found a rule with fully specified data.  We don't
-             // need to go up the tree any further, since the remainder
+    }        // need to go up the tree any further, since the remainder
              // of this branch has already been computed.
 
     // Ask the rule to fill in the properties that it specifies.
@@ -2489,14 +2475,15 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
     RuleDetail oldDetail = detail;
     detail = CheckSpecifiedProperties(aSID, &ruleData);
 
-    if (oldDetail == eRuleNone && detail != eRuleNone)
+    if (oldDetail == eRuleNone && detail != eRuleNone) {
       highestNode = ruleNode;
+    }
 
     if (detail == eRuleFullReset ||
         detail == eRuleFullMixed ||
-        detail == eRuleFullInherited)
+        detail == eRuleFullInherited) {
       break; // We don't need to examine any more rules.  All properties
-             // have been fully specified.
+    }        // have been fully specified.
 
     // Climb up to the next rule in the tree (a less specific rule).
     rootNode = ruleNode;
@@ -2539,8 +2526,9 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
                "can't have start struct and be fully specified");
 
   bool isReset = nsCachedStyleData::IsReset(aSID);
-  if (!highestNode)
+  if (!highestNode) {
     highestNode = rootNode;
+  }
 
   MOZ_ASSERT(!(aSID == eStyleStruct_Variables && startStruct),
              "if we start caching Variables structs in the rule tree, then "
@@ -2629,8 +2617,9 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
     // (detail == eRuleNone), which is the most common case here.
     // We must check |!isReset| because the Compute*Data functions for
     // reset structs wouldn't handle none bits correctly.
-    if (highestNode != this && !isReset)
+    if (highestNode != this && !isReset) {
       PropagateNoneBit(bit, highestNode);
+    }
 
     // All information must necessarily be inherited from our parent style context.
     // In the absence of any computed data in the rule tree and with
@@ -2882,32 +2871,34 @@ nsRuleNode::SetDefaultOnRoot(const nsStyleStructID aSID, nsStyleContext* aContex
       parentdata_ = maybeFakeParentData.ptr();                                \
     }                                                                         \
   }                                                                           \
-  if (eStyleStruct_##type_ == eStyleStruct_Variables)                         \
+  if (eStyleStruct_##type_ == eStyleStruct_Variables) {                       \
     /* no need to copy construct an nsStyleVariables, as we will copy */      \
     /* inherited variables (and call SetUncacheable()) in */                  \
     /* ComputeVariablesData */                                                \
     data_ = new (mPresContext) nsStyle##type_(mPresContext);                  \
-  else if (aStartStruct)                                                      \
+  } else if (aStartStruct) {                                                  \
     /* We only need to compute the delta between this computed data and */    \
     /* our computed data. */                                                  \
     data_ = new (mPresContext)                                                \
             nsStyle##type_(*static_cast<nsStyle##type_*>(aStartStruct));      \
-  else {                                                                      \
+  } else {                                                                    \
     if (aRuleDetail != eRuleFullMixed && aRuleDetail != eRuleFullReset) {     \
       /* No question. We will have to inherit. Go ahead and init */           \
       /* with inherited vals from parent. */                                  \
       conditions.SetUncacheable();                                            \
-      if (parentdata_)                                                        \
+      if (parentdata_) {                                                      \
         data_ = new (mPresContext) nsStyle##type_(*parentdata_);              \
-      else                                                                    \
+      } else {                                                                \
         data_ = new (mPresContext) nsStyle##type_(mPresContext);              \
-    }                                                                         \
-    else                                                                      \
+      }                                                                       \
+    } else {                                                                  \
       data_ = new (mPresContext) nsStyle##type_(mPresContext);                \
+    }	                                                                      \
   }                                                                           \
                                                                               \
-  if (!parentdata_)                                                           \
-    parentdata_ = data_;
+  if (!parentdata_) {                                                         \
+    parentdata_ = data_;                                                      \
+  }                                                                           \
 
 /**
  * Begin an nsRuleNode::Compute*Data function for a reset struct.
@@ -2931,14 +2922,14 @@ nsRuleNode::SetDefaultOnRoot(const nsStyleStructID aSID, nsStyleContext* aContex
   }                                                                           \
                                                                               \
   nsStyle##type_* data_;                                                      \
-  if (aStartStruct)                                                           \
+  if (aStartStruct) {                                                         \
     /* We only need to compute the delta between this computed data and */    \
     /* our computed data. */                                                  \
     data_ = new (mPresContext)                                                \
             nsStyle##type_(*static_cast<nsStyle##type_*>(aStartStruct));      \
-  else                                                                        \
+  } else {                                                                    \
     data_ = new (mPresContext) nsStyle##type_(mPresContext);                  \
-                                                                              \
+  }                                                                            \
   /* If |conditions.Cacheable()| might be true by the time we're done, we */  \
   /* can't call parentContext->Style##type_() since it could recur into */    \
   /* setting the same struct on the same rule node, causing a leak. */        \
@@ -3200,10 +3191,11 @@ nsRuleNode::CalcFontPointSize(int32_t aHTMLSize, int32_t aBasePointSize,
     aHTMLSize--;    // input as 1-7
   }
 
-  if (aHTMLSize < 0)
+  if (aHTMLSize < 0) {
     aHTMLSize = 0;
-  else if (aHTMLSize > 6)
+  } else if (aHTMLSize > 6) {
     aHTMLSize = 6;
+  }
 
   int32_t* column;
   switch (aFontSizeType)
@@ -3224,9 +3216,7 @@ nsRuleNode::CalcFontPointSize(int32_t aHTMLSize, int32_t aBasePointSize,
     } else {
       dFontSize = nsPresContext::CSSPixelsToAppUnits(sStrictFontSizeTable[row][column[aHTMLSize]]);
     }
-  }
-  else
-  {
+  } else {
     int32_t factor = sFontSizeFactors[column[aHTMLSize]];
     dFontSize = (factor * aBasePointSize) / 100;
   }
@@ -3276,8 +3266,9 @@ nsRuleNode::FindNextSmallerFontSize(nscoord aFontSize, int32_t aBasePointSize,
       // find largest index smaller than current
       for (index = indexMax; index >= indexMin; index--) {
         indexFontSize = CalcFontPointSize(index, aBasePointSize, aPresContext, aFontSizeType);
-        if (indexFontSize < aFontSize)
+        if (indexFontSize < aFontSize) {
           break;
+	}
       }
       // set up points beyond table for interpolation purposes
       if (indexFontSize == smallestIndexFontSize) {
@@ -3294,12 +3285,10 @@ nsRuleNode::FindNextSmallerFontSize(nscoord aFontSize, int32_t aBasePointSize,
       relativePosition = float(aFontSize - indexFontSize) / float(largerIndexFontSize - indexFontSize);
       // set the new size to have the same relative position between the next smallest two indexed sizes
       smallerSize = smallerIndexFontSize + NSToCoordRound(relativePosition * (indexFontSize - smallerIndexFontSize));
-    }
-    else {  // larger than HTML table, drop by 33%
+    } else {  // larger than HTML table, drop by 33%
       smallerSize = NSToCoordRound(float(aFontSize) / 1.5);
     }
-  }
-  else { // smaller than HTML table, drop by 1px
+  } else { // smaller than HTML table, drop by 1px
     smallerSize = std::max(aFontSize - onePx, onePx);
   }
   return smallerSize;
@@ -3343,8 +3332,9 @@ nsRuleNode::FindNextLargerFontSize(nscoord aFontSize, int32_t aBasePointSize,
       // find smallest index larger than current
       for (index = indexMin; index <= indexMax; index++) {
         indexFontSize = CalcFontPointSize(index, aBasePointSize, aPresContext, aFontSizeType);
-        if (indexFontSize > aFontSize)
+        if (indexFontSize > aFontSize) {
           break;
+	}
       }
       // set up points beyond table for interpolation purposes
       if (indexFontSize == smallestIndexFontSize) {
@@ -3362,12 +3352,10 @@ nsRuleNode::FindNextLargerFontSize(nscoord aFontSize, int32_t aBasePointSize,
       // set the new size to have the same relative position between the next largest two indexed sizes
       adjustment = NSCoordSaturatingNonnegativeMultiply(largerIndexFontSize - indexFontSize, relativePosition);
       largerSize = NSCoordSaturatingAdd(indexFontSize, adjustment);
-    }
-    else {  // larger than HTML table, increase by 50%
+    } else {  // larger than HTML table, increase by 50%
       largerSize = NSCoordSaturatingMultiply(aFontSize, 1.5);
     }
-  }
-  else { // smaller than HTML table, increase by 1px
+  } else { // smaller than HTML table, increase by 1px
     largerSize = NSCoordSaturatingAdd(aFontSize, onePx);
   }
   return largerSize;
@@ -3412,8 +3400,7 @@ struct SetFontSizeCalcOps : public css::BasicCoordCalcOps,
       if (!aValue.IsRelativeLengthUnit() && mParentFont->mAllowZoom) {
         size = nsStyleFont::ZoomText(mPresContext, size);
       }
-    }
-    else if (eCSSUnit_Percent == aValue.GetUnit()) {
+    } else if (eCSSUnit_Percent == aValue.GetUnit()) {
       mConditions.SetUncacheable();
       // Note that % units use the parent's size unadjusted for scriptlevel
       // changes. A scriptlevel change between us and the parent is simply
@@ -3457,12 +3444,10 @@ nsRuleNode::SetFontSize(nsPresContext* aPresContext,
         (value <= NS_STYLE_FONT_SIZE_XXLARGE)) {
       *aSize = CalcFontPointSize(value, baseSize,
                        aPresContext, eFontSize_CSS);
-    }
-    else if (NS_STYLE_FONT_SIZE_XXXLARGE == value) {
+    } else if (NS_STYLE_FONT_SIZE_XXXLARGE == value) {
       // <font size="7"> is not specified in CSS, so we don't use eFontSize_CSS.
       *aSize = CalcFontPointSize(value, baseSize, aPresContext);
-    }
-    else if (NS_STYLE_FONT_SIZE_LARGER  == value ||
+    } else if (NS_STYLE_FONT_SIZE_LARGER  == value ||
              NS_STYLE_FONT_SIZE_SMALLER == value) {
       aConditions.SetUncacheable();
 
@@ -3482,8 +3467,7 @@ nsRuleNode::SetFontSize(nsPresContext* aPresContext,
 
         NS_ASSERTION(*aSize >= parentSize,
                      "FindNextLargerFontSize failed");
-      }
-      else {
+      } else {
         *aSize = FindNextSmallerFontSize(parentSize,
                          baseSize, aPresContext, eFontSize_CSS);
         NS_ASSERTION(*aSize < parentSize ||
@@ -3493,8 +3477,7 @@ nsRuleNode::SetFontSize(nsPresContext* aPresContext,
     } else {
       NS_NOTREACHED("unexpected value");
     }
-  }
-  else if (sizeValue->IsLengthUnit() ||
+  } else if (sizeValue->IsLengthUnit() ||
            sizeValue->GetUnit() == eCSSUnit_Percent ||
            sizeValue->IsCalcUnit()) {
     SetFontSizeCalcOps ops(aParentSize, aParentFont,
@@ -3510,12 +3493,10 @@ nsRuleNode::SetFontSize(nsPresContext* aPresContext,
     // The calc ops will always zoom its result according to the value
     // of aParentFont->mAllowZoom.
     sizeIsZoomedAccordingToParent = true;
-  }
-  else if (eCSSUnit_System_Font == sizeValue->GetUnit()) {
+  } else if (eCSSUnit_System_Font == sizeValue->GetUnit()) {
     // this becomes our cascading size
     *aSize = aSystemFont.size;
-  }
-  else if (eCSSUnit_Inherit == sizeValue->GetUnit() ||
+  } else if (eCSSUnit_Inherit == sizeValue->GetUnit() ||
            eCSSUnit_Unset == sizeValue->GetUnit()) {
     aConditions.SetUncacheable();
     // We apply scriptlevel change for this case, because the default is
@@ -3523,8 +3504,7 @@ nsRuleNode::SetFontSize(nsPresContext* aPresContext,
     // default.
     *aSize = aScriptLevelAdjustedParentSize;
     sizeIsZoomedAccordingToParent = true;
-  }
-  else if (eCSSUnit_Initial == sizeValue->GetUnit()) {
+  } else if (eCSSUnit_Initial == sizeValue->GetUnit()) {
     // The initial value is 'medium', which has magical sizing based on
     // the generic font family, so do that here too.
     *aSize = baseSize;
@@ -3559,10 +3539,12 @@ nsRuleNode::SetFontSize(nsPresContext* aPresContext,
 }
 
 static int8_t ClampTo8Bit(int32_t aValue) {
-  if (aValue < -128)
+  if (aValue < -128) {
     return -128;
-  if (aValue > 127)
+  }
+  if (aValue > 127) {
     return 127;
+  }
   return int8_t(aValue);
 }
 
@@ -3721,20 +3703,17 @@ nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
     // to have since we'll still want it once we get rid of
     // SetGenericFont (bug 380915).
     aFont->mGenericID = aGenericFontID;
-  }
-  else if (eCSSUnit_System_Font == familyValue->GetUnit()) {
+  } else if (eCSSUnit_System_Font == familyValue->GetUnit()) {
     aFont->mFont.fontlist = systemFont.fontlist;
     aFont->mFont.systemFont = true;
     aFont->mGenericID = kGenericFont_NONE;
-  }
-  else if (eCSSUnit_Inherit == familyValue->GetUnit() ||
+  } else if (eCSSUnit_Inherit == familyValue->GetUnit() ||
            eCSSUnit_Unset == familyValue->GetUnit()) {
     aConditions.SetUncacheable();
     aFont->mFont.fontlist = aParentFont->mFont.fontlist;
     aFont->mFont.systemFont = aParentFont->mFont.systemFont;
     aFont->mGenericID = aParentFont->mGenericID;
-  }
-  else if (eCSSUnit_Initial == familyValue->GetUnit()) {
+  } else if (eCSSUnit_Initial == familyValue->GetUnit()) {
     aFont->mFont.fontlist = defaultVariableFont->fontlist;
     aFont->mFont.systemFont = defaultVariableFont->systemFont;
     aFont->mGenericID = kGenericFont_NONE;
@@ -3862,24 +3841,20 @@ nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
     // "relative"
     aConditions.SetUncacheable();
     aFont->mScriptLevel = ClampTo8Bit(aParentFont->mScriptLevel + scriptLevelValue->GetIntValue());
-  }
-  else if (eCSSUnit_Number == scriptLevelValue->GetUnit()) {
+  } else if (eCSSUnit_Number == scriptLevelValue->GetUnit()) {
     // "absolute"
     aFont->mScriptLevel = ClampTo8Bit(int32_t(scriptLevelValue->GetFloatValue()));
-  }
-  else if (eCSSUnit_Auto == scriptLevelValue->GetUnit()) {
+  } else if (eCSSUnit_Auto == scriptLevelValue->GetUnit()) {
     // auto
     aConditions.SetUncacheable();
     aFont->mScriptLevel = ClampTo8Bit(aParentFont->mScriptLevel +
                                       (aParentFont->mMathDisplay ==
                                        NS_MATHML_DISPLAYSTYLE_INLINE ? 1 : 0));
-  }
-  else if (eCSSUnit_Inherit == scriptLevelValue->GetUnit() ||
+  } else if (eCSSUnit_Inherit == scriptLevelValue->GetUnit() ||
            eCSSUnit_Unset == scriptLevelValue->GetUnit()) {
     aConditions.SetUncacheable();
     aFont->mScriptLevel = aParentFont->mScriptLevel;
-  }
-  else if (eCSSUnit_Initial == scriptLevelValue->GetUnit()) {
+  } else if (eCSSUnit_Initial == scriptLevelValue->GetUnit()) {
     aFont->mScriptLevel = 0;
   }
 
@@ -4150,10 +4125,11 @@ nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
   const nsCSSValue* sizeAdjustValue = aRuleData->ValueForFontSizeAdjust();
   if (eCSSUnit_System_Font == sizeAdjustValue->GetUnit()) {
     aFont->mFont.sizeAdjust = systemFont.sizeAdjust;
-  } else
+  } else {
     SetFactor(*sizeAdjustValue, aFont->mFont.sizeAdjust,
               aConditions, aParentFont->mFont.sizeAdjust, -1.0f,
               SETFCT_NONE | SETFCT_UNSET_INHERIT);
+  }
 }
 
 /* static */ void
@@ -4247,9 +4223,10 @@ nsRuleNode::SetGenericFont(nsPresContext* aPresContext,
     // aStartStruct.
     for (nsRuleNode* ruleNode = context->RuleNode(); ruleNode;
          ruleNode = ruleNode->GetParent()) {
-      if (ruleNode->mNoneBits & fontBit)
+      if (ruleNode->mNoneBits & fontBit) {
         // no more font rules on this branch, get out
         break;
+      }
 
       nsIStyleRule *rule = ruleNode->GetRule();
       if (rule) {
@@ -4263,8 +4240,9 @@ nsRuleNode::SetGenericFont(nsPresContext* aPresContext,
 
     // Avoid unnecessary operations in SetFont().  But we care if it's
     // the final value that we're computing.
-    if (i != 0)
+    if (i != 0) {
       ruleData.ValueForFontFamily()->Reset();
+    }
 
     ResolveVariableReferences(eStyleStruct_Font, &ruleData, aContext);
 
@@ -4351,8 +4329,7 @@ nsRuleNode::ComputeFontData(void* aStartStruct,
     nsRuleNode::SetFont(mPresContext, aContext, generic,
                         aRuleData, parentFont, font,
                         aStartStruct != nullptr, conditions);
-  }
-  else {
+  } else {
     // re-calculate the font as a generic font
     conditions.SetUncacheable();
     nsRuleNode::SetGenericFont(mPresContext, aContext, generic,
@@ -4387,8 +4364,9 @@ GetShadowData(const nsCSSValueList* aList,
   RefPtr<nsCSSShadowArray> shadowList =
     new(arrayLength) nsCSSShadowArray(arrayLength);
 
-  if (!shadowList)
+  if (!shadowList) {
     return nullptr;
+  }
 
   nsStyleCoord tempCoord;
   DebugOnly<bool> unitOK;
@@ -4582,8 +4560,7 @@ struct LengthNumberCalcOps : public css::NumbersAlreadyNormalizedOps
       result.mIsNumber = false;
       result.mValue = CalcLength(aValue, mStyleContext,
                                       mPresContext, mConditions);
-    }
-    else if (eCSSUnit_Number == aValue.GetUnit()) {
+    } else if (eCSSUnit_Number == aValue.GetUnit()) {
       result.mIsNumber = true;
       result.mValue = aValue.GetFloatValue();
     } else {
@@ -4612,14 +4589,12 @@ struct SetLineHeightCalcOps : public LengthNumberCalcOps
       result.mIsNumber = false;
       result.mValue = CalcLength(aValue, mStyleContext,
                                       mPresContext, mConditions);
-    }
-    else if (eCSSUnit_Percent == aValue.GetUnit()) {
+    } else if (eCSSUnit_Percent == aValue.GetUnit()) {
       mConditions.SetUncacheable();
       result.mIsNumber = false;
       nscoord fontSize = mStyleContext->StyleFont()->mFont.size;
       result.mValue = fontSize * aValue.GetPercentValue();
-    }
-    else if (eCSSUnit_Number == aValue.GetUnit()) {
+    } else if (eCSSUnit_Number == aValue.GetUnit()) {
       result.mIsNumber = true;
       result.mValue = aValue.GetFloatValue();
     } else {
@@ -4703,12 +4678,10 @@ nsRuleNode::ComputeTextData(void* aStartStruct,
     text->mLineHeight.SetCoordValue(
         NSToCoordRound(float(aContext->StyleFont()->mFont.size) *
                        lineHeightValue->GetPercentValue()));
-  }
-  else if (eCSSUnit_Initial == lineHeightValue->GetUnit() ||
+  } else if (eCSSUnit_Initial == lineHeightValue->GetUnit() ||
            eCSSUnit_System_Font == lineHeightValue->GetUnit()) {
     text->mLineHeight.SetNormalValue();
-  }
-  else if (eCSSUnit_Calc == lineHeightValue->GetUnit()) {
+  } else if (eCSSUnit_Calc == lineHeightValue->GetUnit()) {
     SetLineHeightCalcOps ops(aContext, mPresContext, conditions);
     LengthNumberCalcObj obj = css::ComputeCalc(*lineHeightValue, ops);
     if (obj.mIsNumber) {
@@ -4717,8 +4690,7 @@ nsRuleNode::ComputeTextData(void* aStartStruct,
       text->mLineHeight.SetCoordValue(
         NSToCoordRoundWithClamp(obj.mValue));
     }
-  }
-  else {
+  } else {
     SetCoord(*lineHeightValue, text->mLineHeight, parentText->mLineHeight,
              SETCOORD_LEH | SETCOORD_FACTOR | SETCOORD_NORMAL |
                SETCOORD_UNSET_INHERIT,
@@ -5046,8 +5018,7 @@ nsRuleNode::ComputeTextResetData(void* aStartStruct,
         mPresContext->GetCachedBoolPref(kPresContext_UnderlineLinks);
       if (underlineLinks) {
         text->mTextDecorationLine |= NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
-      }
-      else {
+      } else {
         text->mTextDecorationLine &= ~NS_STYLE_TEXT_DECORATION_LINE_UNDERLINE;
       }
     }
@@ -5203,11 +5174,9 @@ nsRuleNode::ComputeUserInterfaceData(void* aStartStruct,
       conditions.SetUncacheable();
       ui->mCursor = parentUI->mCursor;
       ui->mCursorImages = parentUI->mCursorImages;
-    }
-    else if (cursorUnit == eCSSUnit_Initial) {
+    } else if (cursorUnit == eCSSUnit_Initial) {
       ui->mCursor = NS_STYLE_CURSOR_AUTO;
-    }
-    else {
+    } else {
       // The parser will never create a list that is *all* URL values --
       // that's invalid.
       MOZ_ASSERT(cursorUnit == eCSSUnit_List || cursorUnit == eCSSUnit_ListDep,
@@ -5440,8 +5409,9 @@ CountTransitionProps(const TransitionPropInfo* aInfo,
     } else {
       data.num = aDisplay->*(info.sdCount);
     }
-    if (data.num > numTransitions)
+    if (data.num > numTransitions) {
       numTransitions = data.num;
+    }
   }
 
   return numTransitions;
@@ -6123,13 +6093,11 @@ nsRuleNode::ComputeDisplayData(void* aStartStruct,
     } else {
       display->mBinding = nullptr;
     }
-  }
-  else if (eCSSUnit_None == bindingValue->GetUnit() ||
+  } else if (eCSSUnit_None == bindingValue->GetUnit() ||
            eCSSUnit_Initial == bindingValue->GetUnit() ||
            eCSSUnit_Unset == bindingValue->GetUnit()) {
     display->mBinding = nullptr;
-  }
-  else if (eCSSUnit_Inherit == bindingValue->GetUnit()) {
+  } else if (eCSSUnit_Inherit == bindingValue->GetUnit()) {
     conditions.SetUncacheable();
     display->mBinding = parentDisplay->mBinding;
   }
@@ -6166,12 +6134,10 @@ nsRuleNode::ComputeDisplayData(void* aStartStruct,
     display->mBreakBefore =
       (NS_STYLE_PAGE_BREAK_AVOID != breakBeforeValue->GetIntValue() &&
        NS_STYLE_PAGE_BREAK_AUTO  != breakBeforeValue->GetIntValue());
-  }
-  else if (eCSSUnit_Initial == breakBeforeValue->GetUnit() ||
+  } else if (eCSSUnit_Initial == breakBeforeValue->GetUnit() ||
            eCSSUnit_Unset == breakBeforeValue->GetUnit()) {
     display->mBreakBefore = false;
-  }
-  else if (eCSSUnit_Inherit == breakBeforeValue->GetUnit()) {
+  } else if (eCSSUnit_Inherit == breakBeforeValue->GetUnit()) {
     conditions.SetUncacheable();
     display->mBreakBefore = parentDisplay->mBreakBefore;
   }
@@ -6181,12 +6147,10 @@ nsRuleNode::ComputeDisplayData(void* aStartStruct,
     display->mBreakAfter =
       (NS_STYLE_PAGE_BREAK_AVOID != breakAfterValue->GetIntValue() &&
        NS_STYLE_PAGE_BREAK_AUTO  != breakAfterValue->GetIntValue());
-  }
-  else if (eCSSUnit_Initial == breakAfterValue->GetUnit() ||
+  } else if (eCSSUnit_Initial == breakAfterValue->GetUnit() ||
            eCSSUnit_Unset == breakAfterValue->GetUnit()) {
     display->mBreakAfter = false;
-  }
-  else if (eCSSUnit_Inherit == breakAfterValue->GetUnit()) {
+  } else if (eCSSUnit_Inherit == breakAfterValue->GetUnit()) {
     conditions.SetUncacheable();
     display->mBreakAfter = parentDisplay->mBreakAfter;
   }
@@ -6245,17 +6209,21 @@ nsRuleNode::ComputeDisplayData(void* aStartStruct,
 
     // NS_STYLE_OVERFLOW_CLIP is a deprecated value, so if it's specified
     // in only one dimension, convert it to NS_STYLE_OVERFLOW_HIDDEN.
-    if (display->mOverflowX == NS_STYLE_OVERFLOW_CLIP)
+    if (display->mOverflowX == NS_STYLE_OVERFLOW_CLIP) {
       display->mOverflowX = NS_STYLE_OVERFLOW_HIDDEN;
-    if (display->mOverflowY == NS_STYLE_OVERFLOW_CLIP)
+    }
+    if (display->mOverflowY == NS_STYLE_OVERFLOW_CLIP) {
       display->mOverflowY = NS_STYLE_OVERFLOW_HIDDEN;
+    }
 
     // If 'visible' is specified but doesn't match the other dimension, it
     // turns into 'auto'.
-    if (display->mOverflowX == NS_STYLE_OVERFLOW_VISIBLE)
+    if (display->mOverflowX == NS_STYLE_OVERFLOW_VISIBLE) {
       display->mOverflowX = NS_STYLE_OVERFLOW_AUTO;
-    if (display->mOverflowY == NS_STYLE_OVERFLOW_VISIBLE)
+    }
+    if (display->mOverflowY == NS_STYLE_OVERFLOW_VISIBLE) {
       display->mOverflowY = NS_STYLE_OVERFLOW_AUTO;
+    }
   }
 
   // When 'contain: paint', update overflow from 'visible' to 'clip'.
@@ -6734,11 +6702,9 @@ nsRuleNode::ComputeColorData(void* aStartStruct,
       colorValue->GetUnit() == eCSSUnit_Unset) {
     color->mColor = parentColor->mColor;
     conditions.SetUncacheable();
-  }
-  else if (colorValue->GetUnit() == eCSSUnit_Initial) {
+  } else if (colorValue->GetUnit() == eCSSUnit_Initial) {
     color->mColor = mPresContext->DefaultColor();
-  }
-  else {
+  } else {
     SetColor(*colorValue, parentColor->mColor, mPresContext, aContext,
              color->mColor, conditions);
   }
@@ -7023,8 +6989,7 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Size>
       const nsCSSValue &specified = aSpecifiedValue->*(axis->specified);
       if (eCSSUnit_Auto == specified.GetUnit()) {
         size.*(axis->type) = nsStyleImageLayers::Size::eAuto;
-      }
-      else if (eCSSUnit_Enumerated == specified.GetUnit()) {
+      } else if (eCSSUnit_Enumerated == specified.GetUnit()) {
         static_assert(nsStyleImageLayers::Size::eContain ==
                       NS_STYLE_IMAGELAYER_SIZE_CONTAIN &&
                       nsStyleImageLayers::Size::eCover ==
@@ -7034,8 +6999,7 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Size>
                    specified.GetIntValue() == NS_STYLE_IMAGELAYER_SIZE_COVER,
                    "invalid enumerated value for size coordinate");
         size.*(axis->type) = specified.GetIntValue();
-      }
-      else if (eCSSUnit_Null == specified.GetUnit()) {
+      } else if (eCSSUnit_Null == specified.GetUnit()) {
         MOZ_ASSERT(axis == gBGSizeAxes + 1,
                    "null allowed only as height value, and only "
                    "for contain/cover/initial/inherit");
@@ -7054,14 +7018,12 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Size>
         }
 #endif
         size.*(axis->type) = size.mWidthType;
-      }
-      else if (eCSSUnit_Percent == specified.GetUnit()) {
+      } else if (eCSSUnit_Percent == specified.GetUnit()) {
         (size.*(axis->result)).mLength = 0;
         (size.*(axis->result)).mPercent = specified.GetPercentValue();
         (size.*(axis->result)).mHasPercent = true;
         size.*(axis->type) = nsStyleImageLayers::Size::eLengthPercentage;
-      }
-      else if (specified.IsLengthUnit()) {
+      } else if (specified.IsLengthUnit()) {
         (size.*(axis->result)).mLength =
           CalcLength(specified, aStyleContext, aStyleContext->PresContext(),
                      aConditions);
@@ -7153,8 +7115,9 @@ SetImageLayerList(nsStyleContext* aStyleContext,
     MOZ_ASSERT(false, "unexpected unit");
   }
 
-  if (aItemCount > aMaxItemCount)
+  if (aItemCount > aMaxItemCount) {
     aMaxItemCount = aItemCount;
+  }
 }
 
 // The same as SetImageLayerList, but for values stored in
@@ -7223,8 +7186,9 @@ SetImageLayerPositionCoordList(
     MOZ_ASSERT(false, "unexpected unit");
   }
 
-  if (aItemCount > aMaxItemCount)
+  if (aItemCount > aMaxItemCount) {
     aMaxItemCount = aItemCount;
+  }
 }
 
 template <class ComputedValueItem>
@@ -7291,8 +7255,9 @@ SetImageLayerPairList(nsStyleContext* aStyleContext,
     MOZ_ASSERT(false, "unexpected unit");
   }
 
-  if (aItemCount > aMaxItemCount)
+  if (aItemCount > aMaxItemCount) {
     aMaxItemCount = aItemCount;
+  }
 }
 
 template <class ComputedValueItem>
@@ -7637,26 +7602,22 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
                      "Unexpected enum value");
         border->SetBorderWidth(side,
                                (mPresContext->GetBorderWidthTable())[value.GetIntValue()]);
-      }
       // OK to pass bad aParentCoord since we're not passing SETCOORD_INHERIT
-      else if (SetCoord(value, coord, nsStyleCoord(),
+      } else if (SetCoord(value, coord, nsStyleCoord(),
                         SETCOORD_LENGTH | SETCOORD_CALC_LENGTH_ONLY,
                         aContext, mPresContext, conditions)) {
         NS_ASSERTION(coord.GetUnit() == eStyleUnit_Coord, "unexpected unit");
         // clamp negative calc() to 0.
         border->SetBorderWidth(side, std::max(coord.GetCoordValue(), 0));
-      }
-      else if (eCSSUnit_Inherit == value.GetUnit()) {
+      } else if (eCSSUnit_Inherit == value.GetUnit()) {
         conditions.SetUncacheable();
         border->SetBorderWidth(side,
                                parentBorder->GetComputedBorder().Side(side));
-      }
-      else if (eCSSUnit_Initial == value.GetUnit() ||
+      } else if (eCSSUnit_Initial == value.GetUnit() ||
                eCSSUnit_Unset == value.GetUnit()) {
         border->SetBorderWidth(side,
           (mPresContext->GetBorderWidthTable())[NS_STYLE_BORDER_WIDTH_MEDIUM]);
-      }
-      else {
+      } else {
         NS_ASSERTION(eCSSUnit_Null == value.GetUnit(),
                      "missing case handling border width");
       }
@@ -7674,12 +7635,10 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
                  "'none' should be handled as enumerated value");
       if (eCSSUnit_Enumerated == unit) {
         border->SetBorderStyle(side, value.GetIntValue());
-      }
-      else if (eCSSUnit_Initial == unit ||
+      } else if (eCSSUnit_Initial == unit ||
                eCSSUnit_Unset == unit) {
         border->SetBorderStyle(side, NS_STYLE_BORDER_STYLE_NONE);
-      }
-      else if (eCSSUnit_Inherit == unit) {
+      } else if (eCSSUnit_Inherit == unit) {
         conditions.SetUncacheable();
         border->SetBorderStyle(side, parentBorder->GetBorderStyle(side));
       }
@@ -7732,9 +7691,9 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
       const nsCSSValueList* list = value.GetListValue();
       while (list) {
         if (SetColor(list->mValue, unused, mPresContext,
-                     aContext, borderColor, conditions))
+                     aContext, borderColor, conditions)) {
           border->AppendBorderColor(side, borderColor);
-        else {
+	} else {
           NS_NOTREACHED("unexpected item in -moz-border-*-colors list");
         }
         list = list->mNext;
@@ -7923,8 +7882,7 @@ nsRuleNode::ComputeOutlineData(void* aStartStruct,
       eCSSUnit_Unset == outlineWidthValue->GetUnit()) {
     outline->mOutlineWidth =
       nsStyleCoord(NS_STYLE_BORDER_WIDTH_MEDIUM, eStyleUnit_Enumerated);
-  }
-  else {
+  } else {
     SetCoord(*outlineWidthValue, outline->mOutlineWidth,
              parentOutline->mOutlineWidth,
              SETCOORD_LEH | SETCOORD_CALC_LENGTH_ONLY, aContext,
@@ -8111,12 +8069,10 @@ nsRuleNode::ComputeListData(void* aStartStruct,
     SetStyleImageRequest([&](nsStyleImageRequest* req) {
       list->mListStyleImage = req;
     }, mPresContext, *imageValue, nsStyleImageRequest::Mode(0));
-  }
-  else if (eCSSUnit_None == imageValue->GetUnit() ||
+  } else if (eCSSUnit_None == imageValue->GetUnit() ||
            eCSSUnit_Initial == imageValue->GetUnit()) {
     list->mListStyleImage = nullptr;
-  }
-  else if (eCSSUnit_Inherit == imageValue->GetUnit() ||
+  } else if (eCSSUnit_Inherit == imageValue->GetUnit() ||
            eCSSUnit_Unset == imageValue->GetUnit()) {
     conditions.SetUncacheable();
     list->mListStyleImage = parentList->mListStyleImage;
@@ -8149,31 +8105,35 @@ nsRuleNode::ComputeListData(void* aStartStruct,
   case eCSSUnit_Rect: {
     const nsCSSRect& rgnRect = imageRegionValue->GetRectValue();
 
-    if (rgnRect.mTop.GetUnit() == eCSSUnit_Auto)
+    if (rgnRect.mTop.GetUnit() == eCSSUnit_Auto) {
       list->mImageRegion.y = 0;
-    else if (rgnRect.mTop.IsLengthUnit())
+    } else if (rgnRect.mTop.IsLengthUnit()) {
       list->mImageRegion.y =
         CalcLength(rgnRect.mTop, aContext, mPresContext, conditions);
+    }
 
-    if (rgnRect.mBottom.GetUnit() == eCSSUnit_Auto)
+    if (rgnRect.mBottom.GetUnit() == eCSSUnit_Auto) {
       list->mImageRegion.height = 0;
-    else if (rgnRect.mBottom.IsLengthUnit())
+    } else if (rgnRect.mBottom.IsLengthUnit()) {
       list->mImageRegion.height =
         CalcLength(rgnRect.mBottom, aContext, mPresContext,
                    conditions) - list->mImageRegion.y;
+    }
 
-    if (rgnRect.mLeft.GetUnit() == eCSSUnit_Auto)
+    if (rgnRect.mLeft.GetUnit() == eCSSUnit_Auto) {
       list->mImageRegion.x = 0;
-    else if (rgnRect.mLeft.IsLengthUnit())
+    } else if (rgnRect.mLeft.IsLengthUnit()) {
       list->mImageRegion.x =
         CalcLength(rgnRect.mLeft, aContext, mPresContext, conditions);
+    }
 
-    if (rgnRect.mRight.GetUnit() == eCSSUnit_Auto)
+    if (rgnRect.mRight.GetUnit() == eCSSUnit_Auto) {
       list->mImageRegion.width = 0;
-    else if (rgnRect.mRight.IsLengthUnit())
+    } else if (rgnRect.mRight.IsLengthUnit()) {
       list->mImageRegion.width =
         CalcLength(rgnRect.mRight, aContext, mPresContext,
                    conditions) - list->mImageRegion.x;
+    }
     break;
   }
 
@@ -8866,8 +8826,9 @@ nsRuleNode::ComputeTableData(void* aStartStruct,
   // span: pixels (not a real CSS prop)
   const nsCSSValue* spanValue = aRuleData->ValueForSpan();
   if (eCSSUnit_Enumerated == spanValue->GetUnit() ||
-      eCSSUnit_Integer == spanValue->GetUnit())
+      eCSSUnit_Integer == spanValue->GetUnit()) {
     table->mSpan = spanValue->GetIntValue();
+  }
 
   COMPUTE_END_RESET(Table, table)
 }
@@ -9267,20 +9228,17 @@ nsRuleNode::ComputeColumnData(void* aStartStruct,
       eCSSUnit_Unset == widthValue.GetUnit()) {
     column->SetColumnRuleWidth(
         (mPresContext->GetBorderWidthTable())[NS_STYLE_BORDER_WIDTH_MEDIUM]);
-  }
-  else if (eCSSUnit_Enumerated == widthValue.GetUnit()) {
+  } else if (eCSSUnit_Enumerated == widthValue.GetUnit()) {
     NS_ASSERTION(widthValue.GetIntValue() == NS_STYLE_BORDER_WIDTH_THIN ||
                  widthValue.GetIntValue() == NS_STYLE_BORDER_WIDTH_MEDIUM ||
                  widthValue.GetIntValue() == NS_STYLE_BORDER_WIDTH_THICK,
                  "Unexpected enum value");
     column->SetColumnRuleWidth(
         (mPresContext->GetBorderWidthTable())[widthValue.GetIntValue()]);
-  }
-  else if (eCSSUnit_Inherit == widthValue.GetUnit()) {
+  } else if (eCSSUnit_Inherit == widthValue.GetUnit()) {
     column->SetColumnRuleWidth(parent->GetComputedColumnRuleWidth());
     conditions.SetUncacheable();
-  }
-  else if (widthValue.IsLengthUnit() || widthValue.IsCalcUnit()) {
+  } else if (widthValue.IsLengthUnit() || widthValue.IsCalcUnit()) {
     nscoord len =
       CalcLength(widthValue, aContext, mPresContext, conditions);
     if (len < 0) {
@@ -9300,12 +9258,10 @@ nsRuleNode::ComputeColumnData(void* aStartStruct,
              "'none' should be handled as enumerated value");
   if (eCSSUnit_Enumerated == styleValue.GetUnit()) {
     column->mColumnRuleStyle = styleValue.GetIntValue();
-  }
-  else if (eCSSUnit_Initial == styleValue.GetUnit() ||
+  } else if (eCSSUnit_Initial == styleValue.GetUnit() ||
            eCSSUnit_Unset == styleValue.GetUnit()) {
     column->mColumnRuleStyle = NS_STYLE_BORDER_STYLE_NONE;
-  }
-  else if (eCSSUnit_Inherit == styleValue.GetUnit()) {
+  } else if (eCSSUnit_Inherit == styleValue.GetUnit()) {
     conditions.SetUncacheable();
     column->mColumnRuleStyle = parent->mColumnRuleStyle;
   }
@@ -10319,8 +10275,7 @@ nsRuleNode::ComputeEffectsData(void* aStartStruct,
     if (clipRect.mTop.GetUnit() == eCSSUnit_Auto) {
       effects->mClip.y = 0;
       effects->mClipFlags |= NS_STYLE_CLIP_TOP_AUTO;
-    }
-    else if (clipRect.mTop.IsLengthUnit()) {
+    } else if (clipRect.mTop.IsLengthUnit()) {
       effects->mClip.y = CalcLength(clipRect.mTop, aContext,
                                     mPresContext, conditions);
     }
@@ -10331,8 +10286,7 @@ nsRuleNode::ComputeEffectsData(void* aStartStruct,
       // nonempty if the actual clip rect could be nonempty.
       effects->mClip.height = NS_MAXSIZE;
       effects->mClipFlags |= NS_STYLE_CLIP_BOTTOM_AUTO;
-    }
-    else if (clipRect.mBottom.IsLengthUnit()) {
+    } else if (clipRect.mBottom.IsLengthUnit()) {
       effects->mClip.height = CalcLength(clipRect.mBottom, aContext,
                                          mPresContext, conditions) -
                               effects->mClip.y;
@@ -10341,8 +10295,7 @@ nsRuleNode::ComputeEffectsData(void* aStartStruct,
     if (clipRect.mLeft.GetUnit() == eCSSUnit_Auto) {
       effects->mClip.x = 0;
       effects->mClipFlags |= NS_STYLE_CLIP_LEFT_AUTO;
-    }
-    else if (clipRect.mLeft.IsLengthUnit()) {
+    } else if (clipRect.mLeft.IsLengthUnit()) {
       effects->mClip.x = CalcLength(clipRect.mLeft, aContext,
                                     mPresContext, conditions);
     }
@@ -10353,8 +10306,7 @@ nsRuleNode::ComputeEffectsData(void* aStartStruct,
       // nonempty if the actual clip rect could be nonempty.
       effects->mClip.width = NS_MAXSIZE;
       effects->mClipFlags |= NS_STYLE_CLIP_RIGHT_AUTO;
-    }
-    else if (clipRect.mRight.IsLengthUnit()) {
+    } else if (clipRect.mRight.IsLengthUnit()) {
       effects->mClip.width = CalcLength(clipRect.mRight, aContext,
                                         mPresContext, conditions) -
                              effects->mClip.x;
@@ -10414,8 +10366,9 @@ nsRuleNode::GetStyleData(nsStyleStructID aSID,
     }
   }
 
-  if (MOZ_UNLIKELY(!aComputeData))
+  if (MOZ_UNLIKELY(!aComputeData)) {
     return nullptr;
+  }
 
   // Nothing is cached.  We'll have to delve further and examine our rules.
   data = WalkRuleTree(aSID, aContext);
@@ -10452,18 +10405,18 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
 #endif
 
   uint32_t inheritBits = 0;
-  if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BACKGROUND)
+  if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BACKGROUND) {
     inheritBits |= NS_STYLE_INHERIT_BIT(Background);
-
-  if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BORDER)
+  }
+  if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BORDER) {
     inheritBits |= NS_STYLE_INHERIT_BIT(Border);
-
-  if (ruleTypeMask & NS_AUTHOR_SPECIFIED_PADDING)
+  }
+  if (ruleTypeMask & NS_AUTHOR_SPECIFIED_PADDING) {
     inheritBits |= NS_STYLE_INHERIT_BIT(Padding);
-
-  if (ruleTypeMask & NS_AUTHOR_SPECIFIED_TEXT_SHADOW)
+  }
+  if (ruleTypeMask & NS_AUTHOR_SPECIFIED_TEXT_SHADOW) {
     inheritBits |= NS_STYLE_INHERIT_BIT(Text);
-
+  }
   // properties in the SIDS, whether or not we care about them
   size_t nprops = 0,
          backgroundOffset, borderOffset, paddingOffset, textShadowOffset;
@@ -10668,12 +10621,16 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
       // eCSSUnit_DummyInherit values to eCSSUnit_Null (so we will be able to
       // detect them being styled by the author) and move up to our parent
       // style context.
-      for (uint32_t i = 0; i < nValues; ++i)
-        if (values[i]->GetUnit() == eCSSUnit_Null)
+      for (uint32_t i = 0; i < nValues; ++i) {
+        if (values[i]->GetUnit() == eCSSUnit_Null) {
           values[i]->SetDummyValue();
-      for (uint32_t i = 0; i < nValues; ++i)
-        if (values[i]->GetUnit() == eCSSUnit_DummyInherit)
+	}
+      }
+      for (uint32_t i = 0; i < nValues; ++i) {
+        if (values[i]->GetUnit() == eCSSUnit_DummyInherit) {
           values[i]->Reset();
+	}
+      }
       styleContext = styleContext->GetParent();
     }
   } while (haveExplicitUAInherit && styleContext);
diff --git a/layout/style/test/test_transitions_per_property.html b/layout/style/test/test_transitions_per_property.html
index b7659adb7d..83524b60d9 100644
--- a/layout/style/test/test_transitions_per_property.html
+++ b/layout/style/test/test_transitions_per_property.html
@@ -248,7 +248,7 @@ var supported_properties = {
     // test_length_percent_calc_transition.
     "stroke-width": [ test_length_transition_svg, test_percent_transition,
                       test_length_clamped_svg, test_percent_clamped ],
-    "-moz-tab-size": [ test_float_zeroToOne_transition,
+    "tab-size": [ test_float_zeroToOne_transition,
                        test_float_aboveOne_transition, test_length_clamped ],
     "text-decoration": [ test_color_shorthand_transition,
                          test_true_currentcolor_shorthand_transition ],

From 3e118e49489d42be44b8cda46ab936071b71d57c Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Sat, 31 Oct 2020 17:31:38 +0100
Subject: [PATCH 06/30] [devtools] More gracefully (than a crash) handle stack
 capture failures.

---
 js/src/jsapi.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index 6ed4d1d89a..dab4c25a43 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -7039,7 +7039,9 @@ JS::CaptureCurrentStack(JSContext* cx, JS::MutableHandleObject stackp,
 {
     AssertHeapIsIdle(cx);
     CHECK_REQUEST(cx);
-    MOZ_RELEASE_ASSERT(cx->compartment());
+    if (!cx->compartment()) {
+      return false;
+    }
 
     JSCompartment* compartment = cx->compartment();
     Rooted<SavedFrame*> frame(cx);

From b69cf124dc814488aeb94166ad034074c5133310 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 14:19:03 -0500
Subject: [PATCH 07/30] Issue #1676 - Part 1: Split MozTesting directives out
 of js/src/moz.build

---
 js/src/js-testing.mozbuild | 48 ++++++++++++++++++++++++++++++++++++++
 js/src/moz.build           | 46 +-----------------------------------
 2 files changed, 49 insertions(+), 45 deletions(-)
 create mode 100644 js/src/js-testing.mozbuild

diff --git a/js/src/js-testing.mozbuild b/js/src/js-testing.mozbuild
new file mode 100644
index 0000000000..a880d98313
--- /dev/null
+++ b/js/src/js-testing.mozbuild
@@ -0,0 +1,48 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+component_engine = ('Core', 'JavaScript Engine')
+component_gc     = ('Core', 'JavaScript: GC')
+component_intl   = ('Core', 'JavaScript: Internationalization API')
+component_jit    = ('Core', 'JavaScript Engine: JIT')
+component_stl    = ('Core', 'JavaScript: Standard Library')
+
+with Files('../public/**'):
+    BUG_COMPONENT = component_engine
+with Files('*'):
+    BUG_COMPONENT = component_engine
+
+with Files('wasm/**'):
+    BUG_COMPONENT = component_jit
+with Files('builtin/**'):
+    BUG_COMPONENT = component_stl
+with Files('ctypes/**'):
+    BUG_COMPONENT = ('Core', 'js-ctypes')
+with Files('gc/**'):
+    BUG_COMPONENT = component_gc
+with Files('jit/**'):
+    BUG_COMPONENT = component_jit
+
+# File-specific metadata
+for gcfile in ['jsgc*', 'devtools/rootAnalysis', 'devtools/gc-ubench', 'devtools/gctrace']:
+    with Files(gcfile):
+        BUG_COMPONENT = component_gc
+for header in ('GCAnnotations.h', 'GCAPI.h', 'HeapAPI.h', 'RootingAPI.h', 'SliceBudget.h', 'SweepingAPI.h', 'TraceKind.h', 'TracingAPI.h', 'WeakMapPtr.h'):
+    with Files('../public/' + header):
+        BUG_COMPONENT = component_gc
+
+for stlfile in ['jsarray.*', 'jsbool*', 'jsdate.*', 'jsnum.*', 'json.*', 'jsstr.*']:
+    with Files(stlfile):
+        BUG_COMPONENT = component_stl
+
+with Files('builtin/Intl*'):
+    BUG_COMPONENT = component_intl
+with Files('builtin/make_intl_data.py'):
+    BUG_COMPONENT = component_intl
+
+with Files('../public/TrackedOptimizationInfo.h'):
+    BUG_COMPONENT = component_jit
+
+TEST_DIRS += ['jsapi-tests', 'tests', 'gdb']
\ No newline at end of file
diff --git a/js/src/moz.build b/js/src/moz.build
index 46a44603e2..c8988fafc4 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -3,60 +3,16 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-# Directory metadata
-component_engine = ('Core', 'JavaScript Engine')
-component_gc     = ('Core', 'JavaScript: GC')
-component_intl   = ('Core', 'JavaScript: Internationalization API')
-component_jit    = ('Core', 'JavaScript Engine: JIT')
-component_stl    = ('Core', 'JavaScript: Standard Library')
+include('js-testing.mozbuild')
 
 FILES_PER_UNIFIED_FILE = 6
 
-with Files('../public/**'):
-    BUG_COMPONENT = component_engine
-with Files('*'):
-    BUG_COMPONENT = component_engine
-
-with Files('wasm/**'):
-    BUG_COMPONENT = component_jit
-with Files('builtin/**'):
-    BUG_COMPONENT = component_stl
-with Files('ctypes/**'):
-    BUG_COMPONENT = ('Core', 'js-ctypes')
-with Files('gc/**'):
-    BUG_COMPONENT = component_gc
-with Files('jit/**'):
-    BUG_COMPONENT = component_jit
-
-# File-specific metadata
-for gcfile in ['jsgc*', 'devtools/rootAnalysis', 'devtools/gc-ubench', 'devtools/gctrace']:
-    with Files(gcfile):
-        BUG_COMPONENT = component_gc
-for header in ('GCAnnotations.h', 'GCAPI.h', 'HeapAPI.h', 'RootingAPI.h', 'SliceBudget.h', 'SweepingAPI.h', 'TraceKind.h', 'TracingAPI.h', 'WeakMapPtr.h'):
-    with Files('../public/' + header):
-        BUG_COMPONENT = component_gc
-
-for stlfile in ['jsarray.*', 'jsbool*', 'jsdate.*', 'jsnum.*', 'json.*', 'jsstr.*']:
-    with Files(stlfile):
-        BUG_COMPONENT = component_stl
-
-with Files('builtin/Intl*'):
-    BUG_COMPONENT = component_intl
-with Files('builtin/make_intl_data.py'):
-    BUG_COMPONENT = component_intl
-
-with Files('../public/TrackedOptimizationInfo.h'):
-    BUG_COMPONENT = component_jit
-
-
 if CONFIG['JS_BUNDLED_EDITLINE']:
     DIRS += ['editline']
 
 if not CONFIG['JS_DISABLE_SHELL']:
     DIRS += ['shell']
 
-TEST_DIRS += ['jsapi-tests', 'tests', 'gdb']
-
 CONFIGURE_SUBST_FILES += [
     'devtools/rootAnalysis/Makefile',
     'js-config',

From 209c7f2305dd9ee6223e5af9e67e4874b1fd735e Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 14:20:26 -0500
Subject: [PATCH 08/30] Issue #1676 - Part 2: Split CFLAGS and CXXFLAGS
 directives out of js/src/moz.build

---
 js/src/js-cxxflags.mozbuild | 42 +++++++++++++++++++++++++++++++++++++
 js/src/moz.build            | 37 +++-----------------------------
 2 files changed, 45 insertions(+), 34 deletions(-)
 create mode 100644 js/src/js-cxxflags.mozbuild

diff --git a/js/src/js-cxxflags.mozbuild b/js/src/js-cxxflags.mozbuild
new file mode 100644
index 0000000000..3cab923f1b
--- /dev/null
+++ b/js/src/js-cxxflags.mozbuild
@@ -0,0 +1,42 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+CFLAGS += CONFIG['MOZ_ICU_CFLAGS']
+CXXFLAGS += CONFIG['MOZ_ICU_CFLAGS']
+
+if CONFIG['_MSC_VER']:
+    # Prevent floating point errors caused by VC++ optimizations
+    CFLAGS += ['-fp:precise']
+    CXXFLAGS += ['-fp:precise']  
+
+    # C4805 warns mixing bool with other integral types in computation.
+    # But given the conversion from bool is specified, and this is a
+    # pattern widely used in code in js/src, suppress this warning here.
+    CXXFLAGS += ['-wd4805']
+
+    # C4661 ("no suitable definition provided for explicit template
+    # instantiation request") is emitted for all Parser methods that
+    # have a Parser<FullParseHandler> definition but no
+    # Parser<SyntaxParseHandler> definition, see bug 1167030.
+    CXXFLAGS += ['-wd4661', '-we4067', '-we4258', '-we4275']
+    CXXFLAGS += ['-wd4146'] # FIXME: unary minus operator applied to unsigned type (bug 1229189)
+
+    # This is intended as a temporary hack to support building with VS2015.
+    # 'noexcept' used with no exception handling mode specified;
+    # termination on exception is not guaranteed. Specify /EHsc
+    CXXFLAGS += ['-wd4577', '-wd4312']
+
+if CONFIG['GNU_CXX']:
+    # Disable strict-aliasing for GCC, which is enabled by default
+    # starting with version 7.1, see Mozilla bug 1363009.
+    CXXFLAGS += ['-Wno-shadow', '-Werror=format', '-fno-strict-aliasing']
+
+if CONFIG['JS_HAS_CTYPES'] and CONFIG['MOZ_SYSTEM_FFI']:
+    CXXFLAGS += CONFIG['MOZ_FFI_CFLAGS']
+
+if CONFIG['JS_CODEGEN_ARM'] and CONFIG['JS_SIMULATOR_ARM']:
+    # Configuration used only for testing.
+    if CONFIG['OS_ARCH'] == 'Linux' or CONFIG['OS_ARCH'] == 'Darwin':
+        CXXFLAGS += [ '-msse2', '-mfpmath=sse' ]
\ No newline at end of file
diff --git a/js/src/moz.build b/js/src/moz.build
index c8988fafc4..09e4714161 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -3,6 +3,7 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+include('js-cxxflags.mozbuild')
 include('js-testing.mozbuild')
 
 FILES_PER_UNIFIED_FILE = 6
@@ -446,9 +447,6 @@ elif CONFIG['JS_CODEGEN_ARM']:
         UNIFIED_SOURCES += [
             'jit/arm/Simulator-arm.cpp'
         ]
-        # Configuration used only for testing.
-        if CONFIG['OS_ARCH'] == 'Linux' or CONFIG['OS_ARCH'] == 'Darwin':
-            CXXFLAGS += [ '-msse2', '-mfpmath=sse' ]
     elif CONFIG['OS_ARCH'] == 'Darwin':
         SOURCES += [
             'jit/arm/llvm-compiler-rt/arm/aeabi_idivmod.S',
@@ -641,26 +639,6 @@ if CONFIG['_MSC_VER']:
         SOURCES['builtin/RegExp.cpp'].no_pgo = True # Bug 772303
     elif CONFIG['CPU_ARCH'] == 'x86_64' and CONFIG['JS_HAS_CTYPES']:
         SOURCES['ctypes/CTypes.cpp'].no_pgo = True # Bug 810661
-    # Prevent floating point errors caused by VC++ optimizations
-    CFLAGS += ['-fp:precise']
-    CXXFLAGS += ['-fp:precise']    
-    # C4805 warns mixing bool with other integral types in computation.
-    # But given the conversion from bool is specified, and this is a
-    # pattern widely used in code in js/src, suppress this warning here.
-    CXXFLAGS += ['-wd4805']
-    # C4661 ("no suitable definition provided for explicit template
-    # instantiation request") is emitted for all Parser methods that
-    # have a Parser<FullParseHandler> definition but no
-    # Parser<SyntaxParseHandler> definition, see bug 1167030.
-    CXXFLAGS += ['-wd4661']
-    CXXFLAGS += ['-we4067', '-we4258', '-we4275']
-    CXXFLAGS += ['-wd4146'] # FIXME: unary minus operator applied to unsigned type (bug 1229189)
-
-    # This is intended as a temporary hack to support building with VS2015.
-    # 'noexcept' used with no exception handling mode specified;
-    # termination on exception is not guaranteed. Specify /EHsc
-    CXXFLAGS += ['-wd4577']
-    CXXFLAGS += ['-wd4312']
 
 if CONFIG['OS_ARCH'] not in ('WINNT'):
     OS_LIBS += [
@@ -687,9 +665,6 @@ if CONFIG['OS_ARCH'] == 'SunOS':
 
 OS_LIBS += CONFIG['REALTIME_LIBS']
 
-CFLAGS += CONFIG['MOZ_ICU_CFLAGS']
-CXXFLAGS += CONFIG['MOZ_ICU_CFLAGS']
-
 NO_EXPAND_LIBS = True
 
 DIST_INSTALL = True
@@ -732,18 +707,12 @@ selfhosted.inputs = [
 ]
 
 if CONFIG['JS_HAS_CTYPES']:
-    if CONFIG['MOZ_SYSTEM_FFI']:
-        CXXFLAGS += CONFIG['MOZ_FFI_CFLAGS']
-    else:
+    if not CONFIG['MOZ_SYSTEM_FFI']:
         # Windows needs this to be linked with a static library.
         DEFINES['FFI_BUILDING'] = True
 
-if CONFIG['GNU_CXX']:
-    # Disable strict-aliasing for GCC, which is enabled by default
-    # starting with version 7.1, see Mozilla bug 1363009.
-    CXXFLAGS += ['-Wno-shadow', '-Werror=format', '-fno-strict-aliasing']
-
 # Suppress warnings in third-party code.
+# We are keeping this in the main moz.build because it is file specific
 if CONFIG['CLANG_CXX'] or CONFIG['GNU_CXX']:
     SOURCES['jsdtoa.cpp'].flags += ['-Wno-implicit-fallthrough']
 

From 55c2ff2df2fda6a8494f494383f7d7b7f78d353e Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 15:20:38 -0500
Subject: [PATCH 09/30] Issue #1676 - Part 3: Split DEFINES out of
 js/src/moz.build

---
 js/src/js-config.mozbuild | 32 ++++++++++++++++++++++++++++++
 js/src/moz.build          | 41 +++++----------------------------------
 2 files changed, 37 insertions(+), 36 deletions(-)
 create mode 100644 js/src/js-config.mozbuild

diff --git a/js/src/js-config.mozbuild b/js/src/js-config.mozbuild
new file mode 100644
index 0000000000..82fb4e53e3
--- /dev/null
+++ b/js/src/js-config.mozbuild
@@ -0,0 +1,32 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Also set in shell/moz.build
+DEFINES['ENABLE_SHARED_ARRAY_BUFFER'] = True
+
+DEFINES['EXPORT_JS_API'] = True
+
+if CONFIG['NIGHTLY_BUILD']:
+    DEFINES['ENABLE_BINARYDATA'] = True
+
+if CONFIG['NIGHTLY_BUILD']:
+    DEFINES['ENABLE_SIMD'] = True
+
+if CONFIG['JS_HAS_CTYPES']:
+    DEFINES['JS_HAS_CTYPES'] = True
+    for var in ('DLL_PREFIX', 'DLL_SUFFIX'):
+        DEFINES[var] = '"%s"' % CONFIG[var]
+
+if CONFIG['MOZ_LINKER']:
+    DEFINES['MOZ_LINKER'] = True
+
+if CONFIG['JS_HAS_CTYPES']:
+    if not CONFIG['MOZ_SYSTEM_FFI']:
+        # Windows needs this to be linked with a static library.
+        DEFINES['FFI_BUILDING'] = True
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    DEFINES['_CRT_RAND_S'] = True
+    DEFINES['NOMINMAX'] = True
\ No newline at end of file
diff --git a/js/src/moz.build b/js/src/moz.build
index 09e4714161..144f21aebf 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -3,6 +3,7 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+include('js-config.mozbuild')
 include('js-cxxflags.mozbuild')
 include('js-testing.mozbuild')
 
@@ -37,7 +38,6 @@ CONFIGURE_DEFINE_FILES += [
 
 if CONFIG['HAVE_DTRACE']:
     GENERATED_FILES += ['javascript-trace.h']
-
     EXPORTS += ['!javascript-trace.h']
 
 # Changes to internal header files, used externally, massively slow down
@@ -538,7 +538,6 @@ if CONFIG['OS_ARCH'] == 'WINNT':
         'threading/windows/Thread.cpp',
     ]
     # _CRT_RAND_S must be #defined before #including stdlib.h to get rand_s()
-    DEFINES['_CRT_RAND_S'] = True
 else:
     SOURCES += [
         'threading/posix/ConditionVariable.cpp',
@@ -615,24 +614,6 @@ USE_LIBS += [
     'zlib',
 ]
 
-if CONFIG['NIGHTLY_BUILD']:
-    DEFINES['ENABLE_BINARYDATA'] = True
-
-if CONFIG['NIGHTLY_BUILD']:
-    DEFINES['ENABLE_SIMD'] = True
-
-# Also set in shell/moz.build
-DEFINES['ENABLE_SHARED_ARRAY_BUFFER'] = True
-
-DEFINES['EXPORT_JS_API'] = True
-
-if CONFIG['JS_HAS_CTYPES']:
-    DEFINES['JS_HAS_CTYPES'] = True
-    for var in ('DLL_PREFIX', 'DLL_SUFFIX'):
-        DEFINES[var] = '"%s"' % CONFIG[var]
-
-if CONFIG['MOZ_LINKER']:
-    DEFINES['MOZ_LINKER'] = True
 
 if CONFIG['_MSC_VER']:
     if CONFIG['CPU_ARCH'] == 'x86':
@@ -641,19 +622,13 @@ if CONFIG['_MSC_VER']:
         SOURCES['ctypes/CTypes.cpp'].no_pgo = True # Bug 810661
 
 if CONFIG['OS_ARCH'] not in ('WINNT'):
-    OS_LIBS += [
-        'm',
-    ]
+    OS_LIBS += ['m']
 
 if CONFIG['OS_ARCH'] == 'FreeBSD':
-    OS_LIBS += [
-        '-pthread',
-    ]
+    OS_LIBS += ['-pthread']
 
 if CONFIG['OS_ARCH'] == 'Linux':
-    OS_LIBS += [
-        'dl',
-    ]
+    OS_LIBS += ['dl']
 
 if CONFIG['OS_ARCH'] == 'SunOS':
     OS_LIBS += [
@@ -706,15 +681,9 @@ selfhosted.inputs = [
     'builtin/WeakSet.js'
 ]
 
-if CONFIG['JS_HAS_CTYPES']:
-    if not CONFIG['MOZ_SYSTEM_FFI']:
-        # Windows needs this to be linked with a static library.
-        DEFINES['FFI_BUILDING'] = True
-
 # Suppress warnings in third-party code.
 # We are keeping this in the main moz.build because it is file specific
 if CONFIG['CLANG_CXX'] or CONFIG['GNU_CXX']:
     SOURCES['jsdtoa.cpp'].flags += ['-Wno-implicit-fallthrough']
 
-if CONFIG['OS_ARCH'] == 'WINNT':
-    DEFINES['NOMINMAX'] = True
+

From bf147b821c4a221d5e47ef67eedfb1ba273a104a Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 16:11:37 -0500
Subject: [PATCH 10/30] Issue #80 - De-unify js/src

Three debug sources are producing link warnings and will be solved as Issue #1676 progresses.

This does not include JS Testing sources.
Specifically: js/src/gdb or js/src/jsapi-tests
---
 js/src/editline/moz.build |  2 +-
 js/src/moz.build          | 30 +++++++++++++++---------------
 js/src/shell/moz.build    |  2 +-
 3 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/js/src/editline/moz.build b/js/src/editline/moz.build
index 420c98df2e..1213854c1a 100644
--- a/js/src/editline/moz.build
+++ b/js/src/editline/moz.build
@@ -5,7 +5,7 @@
 
 Library('editline')
 
-UNIFIED_SOURCES += [
+SOURCES += [
     'editline.c',
     'sysunix.c',
 ]
diff --git a/js/src/moz.build b/js/src/moz.build
index 144f21aebf..25773b3b2e 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -111,7 +111,7 @@ EXPORTS.js += [
     '../public/WeakMapPtr.h',
 ]
 
-UNIFIED_SOURCES += [
+SOURCES += [
     'builtin/AtomicsObject.cpp',
     'builtin/Eval.cpp',
     'builtin/Intl.cpp',
@@ -368,7 +368,7 @@ SOURCES += [
 ]
 
 if CONFIG['JS_POSIX_NSPR']:
-    UNIFIED_SOURCES += [
+    SOURCES += [
         'vm/PosixNSPR.cpp',
     ]
 
@@ -385,11 +385,11 @@ if CONFIG['ENABLE_TRACE_LOGGING']:
     ]
 
 if not CONFIG['ENABLE_ION']:
-    UNIFIED_SOURCES += [
+    SOURCES += [
         'jit/none/Trampoline-none.cpp'
     ]
 elif CONFIG['JS_CODEGEN_X86'] or CONFIG['JS_CODEGEN_X64']:
-    UNIFIED_SOURCES += [
+    SOURCES += [
         'jit/x86-shared/Architecture-x86-shared.cpp',
         'jit/x86-shared/Assembler-x86-shared.cpp',
         'jit/x86-shared/AssemblerBuffer-x86-shared.cpp',
@@ -404,7 +404,7 @@ elif CONFIG['JS_CODEGEN_X86'] or CONFIG['JS_CODEGEN_X64']:
         'jit/x86-shared/Disassembler-x86-shared.cpp',  # using namespace js::jit::X86Encoding;
     ]
     if CONFIG['JS_CODEGEN_X64']:
-        UNIFIED_SOURCES += [
+        SOURCES += [
             'jit/x64/Assembler-x64.cpp',
             'jit/x64/Bailouts-x64.cpp',
             'jit/x64/BaselineCompiler-x64.cpp',
@@ -416,7 +416,7 @@ elif CONFIG['JS_CODEGEN_X86'] or CONFIG['JS_CODEGEN_X64']:
             'jit/x64/Trampoline-x64.cpp',
         ]
     else:
-        UNIFIED_SOURCES += [
+        SOURCES += [
             'jit/x86/Assembler-x86.cpp',
             'jit/x86/Bailouts-x86.cpp',
             'jit/x86/BaselineCompiler-x86.cpp',
@@ -428,7 +428,7 @@ elif CONFIG['JS_CODEGEN_X86'] or CONFIG['JS_CODEGEN_X64']:
             'jit/x86/Trampoline-x86.cpp',
         ]
 elif CONFIG['JS_CODEGEN_ARM']:
-    UNIFIED_SOURCES += [
+    SOURCES += [
         'jit/arm/Architecture-arm.cpp',
         'jit/arm/Assembler-arm.cpp',
         'jit/arm/Bailouts-arm.cpp',
@@ -444,7 +444,7 @@ elif CONFIG['JS_CODEGEN_ARM']:
         'jit/arm/Trampoline-arm.cpp',
     ]
     if CONFIG['JS_SIMULATOR_ARM']:
-        UNIFIED_SOURCES += [
+        SOURCES += [
             'jit/arm/Simulator-arm.cpp'
         ]
     elif CONFIG['OS_ARCH'] == 'Darwin':
@@ -453,7 +453,7 @@ elif CONFIG['JS_CODEGEN_ARM']:
             'jit/arm/llvm-compiler-rt/arm/aeabi_uidivmod.S',
         ]
 elif CONFIG['JS_CODEGEN_ARM64']:
-    UNIFIED_SOURCES += [
+    SOURCES += [
         'jit/arm64/Architecture-arm64.cpp',
         'jit/arm64/Assembler-arm64.cpp',
         'jit/arm64/Bailouts-arm64.cpp',
@@ -476,14 +476,14 @@ elif CONFIG['JS_CODEGEN_ARM64']:
         'jit/arm64/vixl/Utils-vixl.cpp'
     ]
     if CONFIG['JS_SIMULATOR_ARM64']:
-        UNIFIED_SOURCES += [
+        SOURCES += [
             'jit/arm64/vixl/Debugger-vixl.cpp',
             'jit/arm64/vixl/Logic-vixl.cpp',
             'jit/arm64/vixl/MozSimulator-vixl.cpp',
             'jit/arm64/vixl/Simulator-vixl.cpp'
         ]
 elif CONFIG['JS_CODEGEN_MIPS32'] or CONFIG['JS_CODEGEN_MIPS64']:
-    UNIFIED_SOURCES += [
+    SOURCES += [
         'jit/mips-shared/Architecture-mips-shared.cpp',
         'jit/mips-shared/Assembler-mips-shared.cpp',
         'jit/mips-shared/Bailouts-mips-shared.cpp',
@@ -495,7 +495,7 @@ elif CONFIG['JS_CODEGEN_MIPS32'] or CONFIG['JS_CODEGEN_MIPS64']:
         'jit/mips-shared/MoveEmitter-mips-shared.cpp',
     ]
     if CONFIG['JS_CODEGEN_MIPS32']:
-        UNIFIED_SOURCES += [
+        SOURCES += [
             'jit/mips32/Architecture-mips32.cpp',
             'jit/mips32/Assembler-mips32.cpp',
             'jit/mips32/Bailouts-mips32.cpp',
@@ -509,11 +509,11 @@ elif CONFIG['JS_CODEGEN_MIPS32'] or CONFIG['JS_CODEGEN_MIPS64']:
             'jit/mips32/Trampoline-mips32.cpp',
         ]
         if CONFIG['JS_SIMULATOR_MIPS32']:
-            UNIFIED_SOURCES += [
+            SOURCES += [
                 'jit/mips32/Simulator-mips32.cpp'
             ]
     elif CONFIG['JS_CODEGEN_MIPS64']:
-        UNIFIED_SOURCES += [
+        SOURCES += [
             'jit/mips64/Architecture-mips64.cpp',
             'jit/mips64/Assembler-mips64.cpp',
             'jit/mips64/Bailouts-mips64.cpp',
@@ -527,7 +527,7 @@ elif CONFIG['JS_CODEGEN_MIPS32'] or CONFIG['JS_CODEGEN_MIPS64']:
             'jit/mips64/Trampoline-mips64.cpp',
         ]
         if CONFIG['JS_SIMULATOR_MIPS64']:
-            UNIFIED_SOURCES += [
+            SOURCES += [
                 'jit/mips64/Simulator-mips64.cpp'
             ]
 
diff --git a/js/src/shell/moz.build b/js/src/shell/moz.build
index 4f04be73c0..7c861fb0d6 100644
--- a/js/src/shell/moz.build
+++ b/js/src/shell/moz.build
@@ -9,7 +9,7 @@ if CONFIG['JS_SHELL_NAME']:
         USE_LIBS += ['editline']
     USE_LIBS += ['static:js']
 
-UNIFIED_SOURCES += [
+SOURCES += [
     'js.cpp',
     'jsoptparse.cpp',
     'jsshell.cpp',

From 6c5f4618813e985b72ab78ac395c90db216b9ead Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 16:57:05 -0500
Subject: [PATCH 11/30] Issue #1676 - Part 4: Split builtin sources out of
 js/src/moz.build

---
 js/src/builtin/moz.build | 73 ++++++++++++++++++++++++++++++++++++++++
 js/src/moz.build         | 64 +++--------------------------------
 2 files changed, 78 insertions(+), 59 deletions(-)
 create mode 100644 js/src/builtin/moz.build

diff --git a/js/src/builtin/moz.build b/js/src/builtin/moz.build
new file mode 100644
index 0000000000..ebf9318db2
--- /dev/null
+++ b/js/src/builtin/moz.build
@@ -0,0 +1,73 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'AtomicsObject.cpp',
+    'Eval.cpp',
+    'Intl.cpp',
+    'MapObject.cpp',
+    'ModuleObject.cpp',
+    'Object.cpp',
+    'Profilers.cpp',
+    'Promise.cpp',
+    'Reflect.cpp',
+    'ReflectParse.cpp',
+    'RegExp.cpp',
+    'SIMD.cpp',
+    'SymbolObject.cpp',
+    'TestingFunctions.cpp',
+    'TypedObject.cpp',
+    'WeakMapObject.cpp',
+    'WeakSetObject.cpp',
+]
+
+if CONFIG['_MSC_VER']:
+    if CONFIG['CPU_ARCH'] == 'x86':
+        SOURCES['RegExp.cpp'].no_pgo = True # Bug 772303
+
+# Prepare self-hosted JS code for embedding
+GENERATED_FILES += [('selfhosted.out.h', 'selfhosted.js')]
+selfhosted = GENERATED_FILES[('selfhosted.out.h', 'selfhosted.js')]
+selfhosted.script = 'embedjs.py:generate_selfhosted'
+selfhosted.inputs = [
+    '../js.msg',
+    'TypedObjectConstants.h',
+    'SelfHostingDefines.h',
+    'Utilities.js',
+    'Array.js',
+    'AsyncIteration.js',
+    'Classes.js',
+    'Date.js',
+    'Error.js',
+    'Function.js',
+    'Generator.js',
+    'Intl.js',
+    'IntlData.js',
+    'Iterator.js',
+    'Map.js',
+    'Module.js',
+    'Number.js',
+    'Object.js',
+    'Promise.js',
+    'Reflect.js',
+    'RegExp.js',
+    'RegExpGlobalReplaceOpt.h.js',
+    'RegExpLocalReplaceOpt.h.js',
+    'String.js',
+    'Set.js',
+    'Sorting.js',
+    'TypedArray.js',
+    'TypedObject.js',
+    'WeakMap.js',
+    'WeakSet.js',
+]
diff --git a/js/src/moz.build b/js/src/moz.build
index 25773b3b2e..67b25470c0 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -9,6 +9,10 @@ include('js-testing.mozbuild')
 
 FILES_PER_UNIFIED_FILE = 6
 
+DIRS += [
+    'builtin',
+]
+
 if CONFIG['JS_BUNDLED_EDITLINE']:
     DIRS += ['editline']
 
@@ -112,22 +116,6 @@ EXPORTS.js += [
 ]
 
 SOURCES += [
-    'builtin/AtomicsObject.cpp',
-    'builtin/Eval.cpp',
-    'builtin/Intl.cpp',
-    'builtin/MapObject.cpp',
-    'builtin/ModuleObject.cpp',
-    'builtin/Object.cpp',
-    'builtin/Profilers.cpp',
-    'builtin/Promise.cpp',
-    'builtin/Reflect.cpp',
-    'builtin/ReflectParse.cpp',
-    'builtin/SIMD.cpp',
-    'builtin/SymbolObject.cpp',
-    'builtin/TestingFunctions.cpp',
-    'builtin/TypedObject.cpp',
-    'builtin/WeakMapObject.cpp',
-    'builtin/WeakSetObject.cpp',
     'devtools/sharkctl.cpp',
     'ds/LifoAlloc.cpp',
     'ds/MemoryProtectionExceptionHandler.cpp',
@@ -342,8 +330,6 @@ SOURCES += [
 
 # jsarray.cpp and jsatom.cpp cannot be built in unified mode because
 # xpcshell is broken during packaging when compiled with gcc-4.8.2
-# builtin/RegExp.cpp cannot be built in unified mode because it is built
-# without PGO
 # frontend/Parser.cpp cannot be built in unified mode because of explicit
 # template instantiations.
 # jsdtoa.cpp cannot be built in unified mode because we want to suppress
@@ -356,7 +342,6 @@ SOURCES += [
 # instantiations may or may not be needed depending on what it gets bundled
 # with.
 SOURCES += [
-    'builtin/RegExp.cpp',
     'frontend/Parser.cpp',
     'gc/StoreBuffer.cpp',
     'jsarray.cpp',
@@ -616,9 +601,7 @@ USE_LIBS += [
 
 
 if CONFIG['_MSC_VER']:
-    if CONFIG['CPU_ARCH'] == 'x86':
-        SOURCES['builtin/RegExp.cpp'].no_pgo = True # Bug 772303
-    elif CONFIG['CPU_ARCH'] == 'x86_64' and CONFIG['JS_HAS_CTYPES']:
+    if CONFIG['CPU_ARCH'] == 'x86_64' and CONFIG['JS_HAS_CTYPES']:
         SOURCES['ctypes/CTypes.cpp'].no_pgo = True # Bug 810661
 
 if CONFIG['OS_ARCH'] not in ('WINNT'):
@@ -644,43 +627,6 @@ NO_EXPAND_LIBS = True
 
 DIST_INSTALL = True
 
-# Prepare self-hosted JS code for embedding
-GENERATED_FILES += [('selfhosted.out.h', 'selfhosted.js')]
-selfhosted = GENERATED_FILES[('selfhosted.out.h', 'selfhosted.js')]
-selfhosted.script = 'builtin/embedjs.py:generate_selfhosted'
-selfhosted.inputs = [
-    'js.msg',
-    'builtin/TypedObjectConstants.h',
-    'builtin/SelfHostingDefines.h',
-    'builtin/Utilities.js',
-    'builtin/Array.js',
-    'builtin/AsyncIteration.js',
-    'builtin/Classes.js',
-    'builtin/Date.js',
-    'builtin/Error.js',
-    'builtin/Function.js',
-    'builtin/Generator.js',
-    'builtin/Intl.js',
-    'builtin/IntlData.js',
-    'builtin/Iterator.js',
-    'builtin/Map.js',
-    'builtin/Module.js',
-    'builtin/Number.js',
-    'builtin/Object.js',
-    'builtin/Promise.js',
-    'builtin/Reflect.js',
-    'builtin/RegExp.js',
-    'builtin/RegExpGlobalReplaceOpt.h.js',
-    'builtin/RegExpLocalReplaceOpt.h.js',
-    'builtin/String.js',
-    'builtin/Set.js',
-    'builtin/Sorting.js',
-    'builtin/TypedArray.js',
-    'builtin/TypedObject.js',
-    'builtin/WeakMap.js',
-    'builtin/WeakSet.js'
-]
-
 # Suppress warnings in third-party code.
 # We are keeping this in the main moz.build because it is file specific
 if CONFIG['CLANG_CXX'] or CONFIG['GNU_CXX']:

From 1f772961f7e45d434450edcdb84439c3923f6f63 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 17:09:00 -0500
Subject: [PATCH 12/30] Issue #1676 - Part 5: Split devtools sources out of
 js/src/moz.build

---
 js/src/devtools/moz.build | 25 +++++++++++++++++++++++++
 js/src/moz.build          |  8 +-------
 2 files changed, 26 insertions(+), 7 deletions(-)
 create mode 100644 js/src/devtools/moz.build

diff --git a/js/src/devtools/moz.build b/js/src/devtools/moz.build
new file mode 100644
index 0000000000..cb2fc32569
--- /dev/null
+++ b/js/src/devtools/moz.build
@@ -0,0 +1,25 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+CONFIGURE_SUBST_FILES += [
+    'rootAnalysis/Makefile',
+]
+
+SOURCES += [
+    'sharkctl.cpp',
+]
+
+if CONFIG['MOZ_INSTRUMENTS']:
+    SOURCES += [
+        'Instruments.cpp',
+    ]
diff --git a/js/src/moz.build b/js/src/moz.build
index 67b25470c0..8c22ce71d6 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -11,6 +11,7 @@ FILES_PER_UNIFIED_FILE = 6
 
 DIRS += [
     'builtin',
+    'devtools',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -20,7 +21,6 @@ if not CONFIG['JS_DISABLE_SHELL']:
     DIRS += ['shell']
 
 CONFIGURE_SUBST_FILES += [
-    'devtools/rootAnalysis/Makefile',
     'js-config',
     'js.pc',
 ]
@@ -116,7 +116,6 @@ EXPORTS.js += [
 ]
 
 SOURCES += [
-    'devtools/sharkctl.cpp',
     'ds/LifoAlloc.cpp',
     'ds/MemoryProtectionExceptionHandler.cpp',
     'frontend/BytecodeCompiler.cpp',
@@ -357,11 +356,6 @@ if CONFIG['JS_POSIX_NSPR']:
         'vm/PosixNSPR.cpp',
     ]
 
-if CONFIG['MOZ_INSTRUMENTS']:
-    SOURCES += [
-        'devtools/Instruments.cpp',
-    ]
-
 if CONFIG['ENABLE_TRACE_LOGGING']:
     SOURCES += [
         'vm/TraceLogging.cpp',

From c25769b145cffe1ecfe7b754b6a9f096cdaba9ca Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 17:33:42 -0500
Subject: [PATCH 13/30] Issue #1676 - Part 6: Split ds sources out of
 js/src/moz.build

---
 js/src/ds/moz.build | 17 +++++++++++++++++
 js/src/moz.build    |  3 +--
 2 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 js/src/ds/moz.build

diff --git a/js/src/ds/moz.build b/js/src/ds/moz.build
new file mode 100644
index 0000000000..a0b869706c
--- /dev/null
+++ b/js/src/ds/moz.build
@@ -0,0 +1,17 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'LifoAlloc.cpp',
+    'MemoryProtectionExceptionHandler.cpp',
+]
\ No newline at end of file
diff --git a/js/src/moz.build b/js/src/moz.build
index 8c22ce71d6..ca8d95b643 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -12,6 +12,7 @@ FILES_PER_UNIFIED_FILE = 6
 DIRS += [
     'builtin',
     'devtools',
+    'ds',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -116,8 +117,6 @@ EXPORTS.js += [
 ]
 
 SOURCES += [
-    'ds/LifoAlloc.cpp',
-    'ds/MemoryProtectionExceptionHandler.cpp',
     'frontend/BytecodeCompiler.cpp',
     'frontend/BytecodeEmitter.cpp',
     'frontend/FoldConstants.cpp',

From f7a8fe807e0194c68dc74135db180551e056fdf7 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 17:37:32 -0500
Subject: [PATCH 14/30] Issue #1676 - Part 7: Split frontend sources out of
 js/src/moz.build

---
 js/src/frontend/moz.build | 27 +++++++++++++++++++++++++++
 js/src/moz.build          | 17 +----------------
 2 files changed, 28 insertions(+), 16 deletions(-)
 create mode 100644 js/src/frontend/moz.build

diff --git a/js/src/frontend/moz.build b/js/src/frontend/moz.build
new file mode 100644
index 0000000000..55037dd5a4
--- /dev/null
+++ b/js/src/frontend/moz.build
@@ -0,0 +1,27 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'BytecodeCompiler.cpp',
+    'BytecodeEmitter.cpp',
+    'FoldConstants.cpp',
+    'NameFunctions.cpp',
+    'ParseNode.cpp',
+    'Parser.cpp',
+    'TokenStream.cpp',
+]
+
+GENERATED_FILES += ['ReservedWordsGenerated.h']
+ReservedWordsGenerated = GENERATED_FILES['ReservedWordsGenerated.h']
+ReservedWordsGenerated.script = 'GenerateReservedWords.py'
+ReservedWordsGenerated.inputs += ['ReservedWords.h']
\ No newline at end of file
diff --git a/js/src/moz.build b/js/src/moz.build
index ca8d95b643..bcf7680650 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -13,6 +13,7 @@ DIRS += [
     'builtin',
     'devtools',
     'ds',
+    'frontend',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -117,12 +118,6 @@ EXPORTS.js += [
 ]
 
 SOURCES += [
-    'frontend/BytecodeCompiler.cpp',
-    'frontend/BytecodeEmitter.cpp',
-    'frontend/FoldConstants.cpp',
-    'frontend/NameFunctions.cpp',
-    'frontend/ParseNode.cpp',
-    'frontend/TokenStream.cpp',
     'gc/Allocator.cpp',
     'gc/Barrier.cpp',
     'gc/GCTrace.cpp',
@@ -328,8 +323,6 @@ SOURCES += [
 
 # jsarray.cpp and jsatom.cpp cannot be built in unified mode because
 # xpcshell is broken during packaging when compiled with gcc-4.8.2
-# frontend/Parser.cpp cannot be built in unified mode because of explicit
-# template instantiations.
 # jsdtoa.cpp cannot be built in unified mode because we want to suppress
 # compiler warnings in third-party dtoa.c.
 # jsmath.cpp cannot be built in unified mode because it needs to pull rand_s
@@ -340,7 +333,6 @@ SOURCES += [
 # instantiations may or may not be needed depending on what it gets bundled
 # with.
 SOURCES += [
-    'frontend/Parser.cpp',
     'gc/StoreBuffer.cpp',
     'jsarray.cpp',
     'jsatom.cpp',
@@ -550,13 +542,6 @@ else:
         'perf/pm_stub.cpp'
     ]
 
-GENERATED_FILES += ['frontend/ReservedWordsGenerated.h']
-ReservedWordsGenerated = GENERATED_FILES['frontend/ReservedWordsGenerated.h']
-ReservedWordsGenerated.script = 'frontend/GenerateReservedWords.py'
-ReservedWordsGenerated.inputs += [
-    'frontend/ReservedWords.h'
-]
-
 # JavaScript must be built shared, even for static builds, as it is used by
 # other modules which are always built shared. Failure to do so results in
 # the js code getting copied into xpinstall and jsd as well as mozilla-bin,

From 69b861a4911e33304c1476bfba1226b0f1ef1c1f Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 19:07:51 -0500
Subject: [PATCH 15/30] Issue #1676 - Part 8: Fix up include for
 selfhosted.out.h

---
 js/src/vm/SelfHosting.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/js/src/vm/SelfHosting.cpp b/js/src/vm/SelfHosting.cpp
index b7d62efc1d..dc1dfb9fad 100644
--- a/js/src/vm/SelfHosting.cpp
+++ b/js/src/vm/SelfHosting.cpp
@@ -20,8 +20,8 @@
 #include "jsstr.h"
 #include "jsweakmap.h"
 #include "jswrapper.h"
-#include "selfhosted.out.h"
 
+#include "builtin/selfhosted.out.h"
 #include "builtin/Intl.h"
 #include "builtin/MapObject.h"
 #include "builtin/ModuleObject.h"

From c509fb2251eeac6ec3ee6894c122195680a6bf56 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 19:08:56 -0500
Subject: [PATCH 16/30] Issue #1676 - Part 9: Move DIRS down in
 js/src/moz.build

---
 js/src/moz.build | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/js/src/moz.build b/js/src/moz.build
index bcf7680650..f3552db1cb 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -7,21 +7,6 @@ include('js-config.mozbuild')
 include('js-cxxflags.mozbuild')
 include('js-testing.mozbuild')
 
-FILES_PER_UNIFIED_FILE = 6
-
-DIRS += [
-    'builtin',
-    'devtools',
-    'ds',
-    'frontend',
-]
-
-if CONFIG['JS_BUNDLED_EDITLINE']:
-    DIRS += ['editline']
-
-if not CONFIG['JS_DISABLE_SHELL']:
-    DIRS += ['shell']
-
 CONFIGURE_SUBST_FILES += [
     'js-config',
     'js.pc',
@@ -117,6 +102,19 @@ EXPORTS.js += [
     '../public/WeakMapPtr.h',
 ]
 
+DIRS += [
+    'builtin',
+    'devtools',
+    'ds',
+    'frontend',
+]
+
+if CONFIG['JS_BUNDLED_EDITLINE']:
+    DIRS += ['editline']
+
+if not CONFIG['JS_DISABLE_SHELL']:
+    DIRS += ['shell']
+
 SOURCES += [
     'gc/Allocator.cpp',
     'gc/Barrier.cpp',

From 25a9cb15e878163ced146c67e36baf6cbb121d77 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 3 Nov 2020 20:02:33 -0500
Subject: [PATCH 17/30] Issue #1676 - Part 10: Split gc sources out of
 js/src/moz.build

---
 js/src/gc/moz.build | 29 +++++++++++++++++++++++++++++
 js/src/moz.build    | 15 +--------------
 2 files changed, 30 insertions(+), 14 deletions(-)
 create mode 100644 js/src/gc/moz.build

diff --git a/js/src/gc/moz.build b/js/src/gc/moz.build
new file mode 100644
index 0000000000..8f3188cf1f
--- /dev/null
+++ b/js/src/gc/moz.build
@@ -0,0 +1,29 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'Allocator.cpp',
+    'Barrier.cpp',
+    'GCTrace.cpp',
+    'Iteration.cpp',
+    'Marking.cpp',
+    'Memory.cpp',
+    'MemoryProfiler.cpp',
+    'Nursery.cpp',
+    'RootMarking.cpp',
+    'Statistics.cpp',
+    'StoreBuffer.cpp',
+    'Tracer.cpp',
+    'Verifier.cpp',
+    'Zone.cpp',
+]
diff --git a/js/src/moz.build b/js/src/moz.build
index f3552db1cb..7797670c89 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -107,6 +107,7 @@ DIRS += [
     'devtools',
     'ds',
     'frontend',
+    'gc',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -116,19 +117,6 @@ if not CONFIG['JS_DISABLE_SHELL']:
     DIRS += ['shell']
 
 SOURCES += [
-    'gc/Allocator.cpp',
-    'gc/Barrier.cpp',
-    'gc/GCTrace.cpp',
-    'gc/Iteration.cpp',
-    'gc/Marking.cpp',
-    'gc/Memory.cpp',
-    'gc/MemoryProfiler.cpp',
-    'gc/Nursery.cpp',
-    'gc/RootMarking.cpp',
-    'gc/Statistics.cpp',
-    'gc/Tracer.cpp',
-    'gc/Verifier.cpp',
-    'gc/Zone.cpp',
     'irregexp/NativeRegExpMacroAssembler.cpp',
     'irregexp/RegExpAST.cpp',
     'irregexp/RegExpCharacters.cpp',
@@ -331,7 +319,6 @@ SOURCES += [
 # instantiations may or may not be needed depending on what it gets bundled
 # with.
 SOURCES += [
-    'gc/StoreBuffer.cpp',
     'jsarray.cpp',
     'jsatom.cpp',
     'jsdtoa.cpp',

From 96f685e8276ed3ca9ac4a28c5ddec73d1aae1a45 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 13:05:19 -0500
Subject: [PATCH 18/30] Issue #1676 - Part 11: Split irregexp sources out of
 js/src/moz.build

---
 js/src/irregexp/moz.build | 23 +++++++++++++++++++++++
 js/src/moz.build          |  9 +--------
 2 files changed, 24 insertions(+), 8 deletions(-)
 create mode 100644 js/src/irregexp/moz.build

diff --git a/js/src/irregexp/moz.build b/js/src/irregexp/moz.build
new file mode 100644
index 0000000000..fc4fe62188
--- /dev/null
+++ b/js/src/irregexp/moz.build
@@ -0,0 +1,23 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'NativeRegExpMacroAssembler.cpp',
+    'RegExpAST.cpp',
+    'RegExpCharacters.cpp',
+    'RegExpEngine.cpp',
+    'RegExpInterpreter.cpp',
+    'RegExpMacroAssembler.cpp',
+    'RegExpParser.cpp',
+    'RegExpStack.cpp',
+]
\ No newline at end of file
diff --git a/js/src/moz.build b/js/src/moz.build
index 7797670c89..363bb4263f 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -108,6 +108,7 @@ DIRS += [
     'ds',
     'frontend',
     'gc',
+    'irregexp',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -117,14 +118,6 @@ if not CONFIG['JS_DISABLE_SHELL']:
     DIRS += ['shell']
 
 SOURCES += [
-    'irregexp/NativeRegExpMacroAssembler.cpp',
-    'irregexp/RegExpAST.cpp',
-    'irregexp/RegExpCharacters.cpp',
-    'irregexp/RegExpEngine.cpp',
-    'irregexp/RegExpInterpreter.cpp',
-    'irregexp/RegExpMacroAssembler.cpp',
-    'irregexp/RegExpParser.cpp',
-    'irregexp/RegExpStack.cpp',
     'jit/AliasAnalysis.cpp',
     'jit/AliasAnalysisShared.cpp',
     'jit/AlignmentMaskAnalysis.cpp',

From 70db4edd436db03f70ef9b768158591795faa0db Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 13:43:10 -0500
Subject: [PATCH 19/30] Issue #1676 - Part 12: Split jit sources out of
 js/src/moz.build

---
 js/src/jit/moz.build | 231 +++++++++++++++++++++++++++++++++++++++++++
 js/src/moz.build     | 217 +---------------------------------------
 2 files changed, 232 insertions(+), 216 deletions(-)
 create mode 100644 js/src/jit/moz.build

diff --git a/js/src/jit/moz.build b/js/src/jit/moz.build
new file mode 100644
index 0000000000..bcd9b7dbf5
--- /dev/null
+++ b/js/src/jit/moz.build
@@ -0,0 +1,231 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'AliasAnalysis.cpp',
+    'AliasAnalysisShared.cpp',
+    'AlignmentMaskAnalysis.cpp',
+    'BacktrackingAllocator.cpp',
+    'Bailouts.cpp',
+    'BaselineBailouts.cpp',
+    'BaselineCacheIR.cpp',
+    'BaselineCompiler.cpp',
+    'BaselineDebugModeOSR.cpp',
+    'BaselineFrame.cpp',
+    'BaselineFrameInfo.cpp',
+    'BaselineIC.cpp',
+    'BaselineInspector.cpp',
+    'BaselineJIT.cpp',
+    'BitSet.cpp',
+    'BytecodeAnalysis.cpp',
+    'C1Spewer.cpp',
+    'CacheIR.cpp',
+    'CodeGenerator.cpp',
+    'CompileWrappers.cpp',
+    'Disassembler.cpp',
+    'EagerSimdUnbox.cpp',
+    'EdgeCaseAnalysis.cpp',
+    'EffectiveAddressAnalysis.cpp',
+    'ExecutableAllocator.cpp',
+    'FlowAliasAnalysis.cpp',
+    'FoldLinearArithConstants.cpp',
+    'InstructionReordering.cpp',
+    'Ion.cpp',
+    'IonAnalysis.cpp',
+    'IonBuilder.cpp',
+    'IonCaches.cpp',
+    'IonOptimizationLevels.cpp',
+    'JitcodeMap.cpp',
+    'JitFrames.cpp',
+    'JitOptions.cpp',
+    'JitSpewer.cpp',
+    'JSONSpewer.cpp',
+    'LICM.cpp',
+    'Linker.cpp',
+    'LIR.cpp',
+    'LoopUnroller.cpp',
+    'Lowering.cpp',
+    'MacroAssembler.cpp',
+    'MCallOptimize.cpp',
+    'MIR.cpp',
+    'MIRGraph.cpp',
+    'MoveResolver.cpp',
+    'OptimizationTracking.cpp',
+    'PerfSpewer.cpp',
+    'ProcessExecutableMemory.cpp',
+    'RangeAnalysis.cpp',
+    'Recover.cpp',
+    'RegisterAllocator.cpp',
+    'RematerializedFrame.cpp',
+    'Safepoints.cpp',
+    'ScalarReplacement.cpp',
+    'shared/BaselineCompiler-shared.cpp',
+    'shared/CodeGenerator-shared.cpp',
+    'shared/Lowering-shared.cpp',
+    'SharedIC.cpp',
+    'Sink.cpp',
+    'Snapshots.cpp',
+    'StupidAllocator.cpp',
+    'TypedObjectPrediction.cpp',
+    'TypePolicy.cpp',
+    'ValueNumbering.cpp',
+    'VMFunctions.cpp',
+    'WasmBCE.cpp',
+]
+
+if not CONFIG['ENABLE_ION']:
+    SOURCES += [
+        'none/Trampoline-none.cpp'
+    ]
+elif CONFIG['JS_CODEGEN_X86'] or CONFIG['JS_CODEGEN_X64']:
+    SOURCES += [
+        'x86-shared/Architecture-x86-shared.cpp',
+        'x86-shared/Assembler-x86-shared.cpp',
+        'x86-shared/AssemblerBuffer-x86-shared.cpp',
+        'x86-shared/BaselineCompiler-x86-shared.cpp',
+        'x86-shared/BaselineIC-x86-shared.cpp',
+        'x86-shared/CodeGenerator-x86-shared.cpp',
+        'x86-shared/Lowering-x86-shared.cpp',
+        'x86-shared/MacroAssembler-x86-shared.cpp',
+        'x86-shared/MoveEmitter-x86-shared.cpp',
+    ]
+    SOURCES += [
+        'x86-shared/Disassembler-x86-shared.cpp',  # using namespace js::jit::X86Encoding;
+    ]
+    if CONFIG['JS_CODEGEN_X64']:
+        SOURCES += [
+            'x64/Assembler-x64.cpp',
+            'x64/Bailouts-x64.cpp',
+            'x64/BaselineCompiler-x64.cpp',
+            'x64/BaselineIC-x64.cpp',
+            'x64/CodeGenerator-x64.cpp',
+            'x64/Lowering-x64.cpp',
+            'x64/MacroAssembler-x64.cpp',
+            'x64/SharedIC-x64.cpp',
+            'x64/Trampoline-x64.cpp',
+        ]
+    else:
+        SOURCES += [
+            'x86/Assembler-x86.cpp',
+            'x86/Bailouts-x86.cpp',
+            'x86/BaselineCompiler-x86.cpp',
+            'x86/BaselineIC-x86.cpp',
+            'x86/CodeGenerator-x86.cpp',
+            'x86/Lowering-x86.cpp',
+            'x86/MacroAssembler-x86.cpp',
+            'x86/SharedIC-x86.cpp',
+            'x86/Trampoline-x86.cpp',
+        ]
+elif CONFIG['JS_CODEGEN_ARM']:
+    SOURCES += [
+        'arm/Architecture-arm.cpp',
+        'arm/Assembler-arm.cpp',
+        'arm/Bailouts-arm.cpp',
+        'arm/BaselineCompiler-arm.cpp',
+        'arm/BaselineIC-arm.cpp',
+        'arm/CodeGenerator-arm.cpp',
+        'arm/disasm/Constants-arm.cpp',
+        'arm/disasm/Disasm-arm.cpp',
+        'arm/Lowering-arm.cpp',
+        'arm/MacroAssembler-arm.cpp',
+        'arm/MoveEmitter-arm.cpp',
+        'arm/SharedIC-arm.cpp',
+        'arm/Trampoline-arm.cpp',
+    ]
+    if CONFIG['JS_SIMULATOR_ARM']:
+        SOURCES += [
+            'arm/Simulator-arm.cpp'
+        ]
+    elif CONFIG['OS_ARCH'] == 'Darwin':
+        SOURCES += [
+            'arm/llvm-compiler-rt/arm/aeabi_idivmod.S',
+            'arm/llvm-compiler-rt/arm/aeabi_uidivmod.S',
+        ]
+elif CONFIG['JS_CODEGEN_ARM64']:
+    SOURCES += [
+        'arm64/Architecture-arm64.cpp',
+        'arm64/Assembler-arm64.cpp',
+        'arm64/Bailouts-arm64.cpp',
+        'arm64/BaselineIC-arm64.cpp',
+        'arm64/CodeGenerator-arm64.cpp',
+        'arm64/Lowering-arm64.cpp',
+        'arm64/MacroAssembler-arm64.cpp',
+        'arm64/MoveEmitter-arm64.cpp',
+        'arm64/SharedIC-arm64.cpp',
+        'arm64/Trampoline-arm64.cpp',
+        'arm64/vixl/Assembler-vixl.cpp',
+        'arm64/vixl/Cpu-vixl.cpp',
+        'arm64/vixl/Decoder-vixl.cpp',
+        'arm64/vixl/Disasm-vixl.cpp',
+        'arm64/vixl/Instructions-vixl.cpp',
+        'arm64/vixl/Instrument-vixl.cpp',
+        'arm64/vixl/MacroAssembler-vixl.cpp',
+        'arm64/vixl/MozAssembler-vixl.cpp',
+        'arm64/vixl/MozInstructions-vixl.cpp',
+        'arm64/vixl/Utils-vixl.cpp'
+    ]
+    if CONFIG['JS_SIMULATOR_ARM64']:
+        SOURCES += [
+            'arm64/vixl/Debugger-vixl.cpp',
+            'arm64/vixl/Logic-vixl.cpp',
+            'arm64/vixl/MozSimulator-vixl.cpp',
+            'arm64/vixl/Simulator-vixl.cpp'
+        ]
+elif CONFIG['JS_CODEGEN_MIPS32'] or CONFIG['JS_CODEGEN_MIPS64']:
+    SOURCES += [
+        'mips-shared/Architecture-mips-shared.cpp',
+        'mips-shared/Assembler-mips-shared.cpp',
+        'mips-shared/Bailouts-mips-shared.cpp',
+        'mips-shared/BaselineCompiler-mips-shared.cpp',
+        'mips-shared/BaselineIC-mips-shared.cpp',
+        'mips-shared/CodeGenerator-mips-shared.cpp',
+        'mips-shared/Lowering-mips-shared.cpp',
+        'mips-shared/MacroAssembler-mips-shared.cpp',
+        'mips-shared/MoveEmitter-mips-shared.cpp',
+    ]
+    if CONFIG['JS_CODEGEN_MIPS32']:
+        SOURCES += [
+            'mips32/Architecture-mips32.cpp',
+            'mips32/Assembler-mips32.cpp',
+            'mips32/Bailouts-mips32.cpp',
+            'mips32/BaselineCompiler-mips32.cpp',
+            'mips32/BaselineIC-mips32.cpp',
+            'mips32/CodeGenerator-mips32.cpp',
+            'mips32/Lowering-mips32.cpp',
+            'mips32/MacroAssembler-mips32.cpp',
+            'mips32/MoveEmitter-mips32.cpp',
+            'mips32/SharedIC-mips32.cpp',
+            'mips32/Trampoline-mips32.cpp',
+        ]
+        if CONFIG['JS_SIMULATOR_MIPS32']:
+            SOURCES += [
+                'mips32/Simulator-mips32.cpp'
+            ]
+    elif CONFIG['JS_CODEGEN_MIPS64']:
+        SOURCES += [
+            'mips64/Architecture-mips64.cpp',
+            'mips64/Assembler-mips64.cpp',
+            'mips64/Bailouts-mips64.cpp',
+            'mips64/BaselineCompiler-mips64.cpp',
+            'mips64/BaselineIC-mips64.cpp',
+            'mips64/CodeGenerator-mips64.cpp',
+            'mips64/Lowering-mips64.cpp',
+            'mips64/MacroAssembler-mips64.cpp',
+            'mips64/MoveEmitter-mips64.cpp',
+            'mips64/SharedIC-mips64.cpp',
+            'mips64/Trampoline-mips64.cpp',
+        ]
+        if CONFIG['JS_SIMULATOR_MIPS64']:
+            SOURCES += [
+                'mips64/Simulator-mips64.cpp'
+            ]
diff --git a/js/src/moz.build b/js/src/moz.build
index 363bb4263f..906d5c0f73 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -109,6 +109,7 @@ DIRS += [
     'frontend',
     'gc',
     'irregexp',
+    'jit',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -118,75 +119,6 @@ if not CONFIG['JS_DISABLE_SHELL']:
     DIRS += ['shell']
 
 SOURCES += [
-    'jit/AliasAnalysis.cpp',
-    'jit/AliasAnalysisShared.cpp',
-    'jit/AlignmentMaskAnalysis.cpp',
-    'jit/BacktrackingAllocator.cpp',
-    'jit/Bailouts.cpp',
-    'jit/BaselineBailouts.cpp',
-    'jit/BaselineCacheIR.cpp',
-    'jit/BaselineCompiler.cpp',
-    'jit/BaselineDebugModeOSR.cpp',
-    'jit/BaselineFrame.cpp',
-    'jit/BaselineFrameInfo.cpp',
-    'jit/BaselineIC.cpp',
-    'jit/BaselineInspector.cpp',
-    'jit/BaselineJIT.cpp',
-    'jit/BitSet.cpp',
-    'jit/BytecodeAnalysis.cpp',
-    'jit/C1Spewer.cpp',
-    'jit/CacheIR.cpp',
-    'jit/CodeGenerator.cpp',
-    'jit/CompileWrappers.cpp',
-    'jit/Disassembler.cpp',
-    'jit/EagerSimdUnbox.cpp',
-    'jit/EdgeCaseAnalysis.cpp',
-    'jit/EffectiveAddressAnalysis.cpp',
-    'jit/ExecutableAllocator.cpp',
-    'jit/FlowAliasAnalysis.cpp',
-    'jit/FoldLinearArithConstants.cpp',
-    'jit/InstructionReordering.cpp',
-    'jit/Ion.cpp',
-    'jit/IonAnalysis.cpp',
-    'jit/IonBuilder.cpp',
-    'jit/IonCaches.cpp',
-    'jit/IonOptimizationLevels.cpp',
-    'jit/JitcodeMap.cpp',
-    'jit/JitFrames.cpp',
-    'jit/JitOptions.cpp',
-    'jit/JitSpewer.cpp',
-    'jit/JSONSpewer.cpp',
-    'jit/LICM.cpp',
-    'jit/Linker.cpp',
-    'jit/LIR.cpp',
-    'jit/LoopUnroller.cpp',
-    'jit/Lowering.cpp',
-    'jit/MacroAssembler.cpp',
-    'jit/MCallOptimize.cpp',
-    'jit/MIR.cpp',
-    'jit/MIRGraph.cpp',
-    'jit/MoveResolver.cpp',
-    'jit/OptimizationTracking.cpp',
-    'jit/PerfSpewer.cpp',
-    'jit/ProcessExecutableMemory.cpp',
-    'jit/RangeAnalysis.cpp',
-    'jit/Recover.cpp',
-    'jit/RegisterAllocator.cpp',
-    'jit/RematerializedFrame.cpp',
-    'jit/Safepoints.cpp',
-    'jit/ScalarReplacement.cpp',
-    'jit/shared/BaselineCompiler-shared.cpp',
-    'jit/shared/CodeGenerator-shared.cpp',
-    'jit/shared/Lowering-shared.cpp',
-    'jit/SharedIC.cpp',
-    'jit/Sink.cpp',
-    'jit/Snapshots.cpp',
-    'jit/StupidAllocator.cpp',
-    'jit/TypedObjectPrediction.cpp',
-    'jit/TypePolicy.cpp',
-    'jit/ValueNumbering.cpp',
-    'jit/VMFunctions.cpp',
-    'jit/WasmBCE.cpp',
     'jsalloc.cpp',
     'jsapi.cpp',
     'jsbool.cpp',
@@ -332,153 +264,6 @@ if CONFIG['ENABLE_TRACE_LOGGING']:
         'vm/TraceLoggingTypes.cpp',
     ]
 
-if not CONFIG['ENABLE_ION']:
-    SOURCES += [
-        'jit/none/Trampoline-none.cpp'
-    ]
-elif CONFIG['JS_CODEGEN_X86'] or CONFIG['JS_CODEGEN_X64']:
-    SOURCES += [
-        'jit/x86-shared/Architecture-x86-shared.cpp',
-        'jit/x86-shared/Assembler-x86-shared.cpp',
-        'jit/x86-shared/AssemblerBuffer-x86-shared.cpp',
-        'jit/x86-shared/BaselineCompiler-x86-shared.cpp',
-        'jit/x86-shared/BaselineIC-x86-shared.cpp',
-        'jit/x86-shared/CodeGenerator-x86-shared.cpp',
-        'jit/x86-shared/Lowering-x86-shared.cpp',
-        'jit/x86-shared/MacroAssembler-x86-shared.cpp',
-        'jit/x86-shared/MoveEmitter-x86-shared.cpp',
-    ]
-    SOURCES += [
-        'jit/x86-shared/Disassembler-x86-shared.cpp',  # using namespace js::jit::X86Encoding;
-    ]
-    if CONFIG['JS_CODEGEN_X64']:
-        SOURCES += [
-            'jit/x64/Assembler-x64.cpp',
-            'jit/x64/Bailouts-x64.cpp',
-            'jit/x64/BaselineCompiler-x64.cpp',
-            'jit/x64/BaselineIC-x64.cpp',
-            'jit/x64/CodeGenerator-x64.cpp',
-            'jit/x64/Lowering-x64.cpp',
-            'jit/x64/MacroAssembler-x64.cpp',
-            'jit/x64/SharedIC-x64.cpp',
-            'jit/x64/Trampoline-x64.cpp',
-        ]
-    else:
-        SOURCES += [
-            'jit/x86/Assembler-x86.cpp',
-            'jit/x86/Bailouts-x86.cpp',
-            'jit/x86/BaselineCompiler-x86.cpp',
-            'jit/x86/BaselineIC-x86.cpp',
-            'jit/x86/CodeGenerator-x86.cpp',
-            'jit/x86/Lowering-x86.cpp',
-            'jit/x86/MacroAssembler-x86.cpp',
-            'jit/x86/SharedIC-x86.cpp',
-            'jit/x86/Trampoline-x86.cpp',
-        ]
-elif CONFIG['JS_CODEGEN_ARM']:
-    SOURCES += [
-        'jit/arm/Architecture-arm.cpp',
-        'jit/arm/Assembler-arm.cpp',
-        'jit/arm/Bailouts-arm.cpp',
-        'jit/arm/BaselineCompiler-arm.cpp',
-        'jit/arm/BaselineIC-arm.cpp',
-        'jit/arm/CodeGenerator-arm.cpp',
-        'jit/arm/disasm/Constants-arm.cpp',
-        'jit/arm/disasm/Disasm-arm.cpp',
-        'jit/arm/Lowering-arm.cpp',
-        'jit/arm/MacroAssembler-arm.cpp',
-        'jit/arm/MoveEmitter-arm.cpp',
-        'jit/arm/SharedIC-arm.cpp',
-        'jit/arm/Trampoline-arm.cpp',
-    ]
-    if CONFIG['JS_SIMULATOR_ARM']:
-        SOURCES += [
-            'jit/arm/Simulator-arm.cpp'
-        ]
-    elif CONFIG['OS_ARCH'] == 'Darwin':
-        SOURCES += [
-            'jit/arm/llvm-compiler-rt/arm/aeabi_idivmod.S',
-            'jit/arm/llvm-compiler-rt/arm/aeabi_uidivmod.S',
-        ]
-elif CONFIG['JS_CODEGEN_ARM64']:
-    SOURCES += [
-        'jit/arm64/Architecture-arm64.cpp',
-        'jit/arm64/Assembler-arm64.cpp',
-        'jit/arm64/Bailouts-arm64.cpp',
-        'jit/arm64/BaselineIC-arm64.cpp',
-        'jit/arm64/CodeGenerator-arm64.cpp',
-        'jit/arm64/Lowering-arm64.cpp',
-        'jit/arm64/MacroAssembler-arm64.cpp',
-        'jit/arm64/MoveEmitter-arm64.cpp',
-        'jit/arm64/SharedIC-arm64.cpp',
-        'jit/arm64/Trampoline-arm64.cpp',
-        'jit/arm64/vixl/Assembler-vixl.cpp',
-        'jit/arm64/vixl/Cpu-vixl.cpp',
-        'jit/arm64/vixl/Decoder-vixl.cpp',
-        'jit/arm64/vixl/Disasm-vixl.cpp',
-        'jit/arm64/vixl/Instructions-vixl.cpp',
-        'jit/arm64/vixl/Instrument-vixl.cpp',
-        'jit/arm64/vixl/MacroAssembler-vixl.cpp',
-        'jit/arm64/vixl/MozAssembler-vixl.cpp',
-        'jit/arm64/vixl/MozInstructions-vixl.cpp',
-        'jit/arm64/vixl/Utils-vixl.cpp'
-    ]
-    if CONFIG['JS_SIMULATOR_ARM64']:
-        SOURCES += [
-            'jit/arm64/vixl/Debugger-vixl.cpp',
-            'jit/arm64/vixl/Logic-vixl.cpp',
-            'jit/arm64/vixl/MozSimulator-vixl.cpp',
-            'jit/arm64/vixl/Simulator-vixl.cpp'
-        ]
-elif CONFIG['JS_CODEGEN_MIPS32'] or CONFIG['JS_CODEGEN_MIPS64']:
-    SOURCES += [
-        'jit/mips-shared/Architecture-mips-shared.cpp',
-        'jit/mips-shared/Assembler-mips-shared.cpp',
-        'jit/mips-shared/Bailouts-mips-shared.cpp',
-        'jit/mips-shared/BaselineCompiler-mips-shared.cpp',
-        'jit/mips-shared/BaselineIC-mips-shared.cpp',
-        'jit/mips-shared/CodeGenerator-mips-shared.cpp',
-        'jit/mips-shared/Lowering-mips-shared.cpp',
-        'jit/mips-shared/MacroAssembler-mips-shared.cpp',
-        'jit/mips-shared/MoveEmitter-mips-shared.cpp',
-    ]
-    if CONFIG['JS_CODEGEN_MIPS32']:
-        SOURCES += [
-            'jit/mips32/Architecture-mips32.cpp',
-            'jit/mips32/Assembler-mips32.cpp',
-            'jit/mips32/Bailouts-mips32.cpp',
-            'jit/mips32/BaselineCompiler-mips32.cpp',
-            'jit/mips32/BaselineIC-mips32.cpp',
-            'jit/mips32/CodeGenerator-mips32.cpp',
-            'jit/mips32/Lowering-mips32.cpp',
-            'jit/mips32/MacroAssembler-mips32.cpp',
-            'jit/mips32/MoveEmitter-mips32.cpp',
-            'jit/mips32/SharedIC-mips32.cpp',
-            'jit/mips32/Trampoline-mips32.cpp',
-        ]
-        if CONFIG['JS_SIMULATOR_MIPS32']:
-            SOURCES += [
-                'jit/mips32/Simulator-mips32.cpp'
-            ]
-    elif CONFIG['JS_CODEGEN_MIPS64']:
-        SOURCES += [
-            'jit/mips64/Architecture-mips64.cpp',
-            'jit/mips64/Assembler-mips64.cpp',
-            'jit/mips64/Bailouts-mips64.cpp',
-            'jit/mips64/BaselineCompiler-mips64.cpp',
-            'jit/mips64/BaselineIC-mips64.cpp',
-            'jit/mips64/CodeGenerator-mips64.cpp',
-            'jit/mips64/Lowering-mips64.cpp',
-            'jit/mips64/MacroAssembler-mips64.cpp',
-            'jit/mips64/MoveEmitter-mips64.cpp',
-            'jit/mips64/SharedIC-mips64.cpp',
-            'jit/mips64/Trampoline-mips64.cpp',
-        ]
-        if CONFIG['JS_SIMULATOR_MIPS64']:
-            SOURCES += [
-                'jit/mips64/Simulator-mips64.cpp'
-            ]
-
 if CONFIG['OS_ARCH'] == 'WINNT':
     SOURCES += [
         'threading/windows/ConditionVariable.cpp',

From 155a0fbe41ff6c4f66364cb15020dfa6be39725f Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 13:48:57 -0500
Subject: [PATCH 20/30] Issue #1676 - Part 13: Split perf sources out of
 js/src/moz.build

---
 js/src/moz.build      | 14 +-------------
 js/src/perf/moz.build | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 13 deletions(-)
 create mode 100644 js/src/perf/moz.build

diff --git a/js/src/moz.build b/js/src/moz.build
index 906d5c0f73..71147dc8d6 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -49,7 +49,6 @@ EXPORTS += [
     'jstypes.h',
     'jsversion.h',
     'jswrapper.h',
-    'perf/jsperf.h',
 ]
 
 # If you add a header here, add it to js/src/jsapi-tests/testIntTypesABI.cpp so
@@ -110,6 +109,7 @@ DIRS += [
     'gc',
     'irregexp',
     'jit',
+    'perf',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -140,7 +140,6 @@ SOURCES += [
     'jsscript.cpp',
     'jsstr.cpp',
     'jsweakmap.cpp',
-    'perf/jsperf.cpp',
     'proxy/BaseProxyHandler.cpp',
     'proxy/CrossCompartmentWrapper.cpp',
     'proxy/DeadObjectProxy.cpp',
@@ -294,17 +293,6 @@ if CONFIG['MOZ_VTUNE']:
         'vtune/jitprofiling.c'
     ]
 
-if CONFIG['HAVE_LINUX_PERF_EVENT_H']:
-    SOURCES += [
-        'perf/pm_linux.cpp'
-    ]
-    if CONFIG['LINUX_HEADERS_INCLUDES']:
-        SOURCES['perf/pm_linux.cpp'].flags += [CONFIG['LINUX_HEADERS_INCLUDES']]
-else:
-    SOURCES += [
-        'perf/pm_stub.cpp'
-    ]
-
 # JavaScript must be built shared, even for static builds, as it is used by
 # other modules which are always built shared. Failure to do so results in
 # the js code getting copied into xpinstall and jsd as well as mozilla-bin,
diff --git a/js/src/perf/moz.build b/js/src/perf/moz.build
new file mode 100644
index 0000000000..f0dd7e1d67
--- /dev/null
+++ b/js/src/perf/moz.build
@@ -0,0 +1,29 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+EXPORTS += ['jsperf.h']
+
+SOURCES += [
+    'jsperf.cpp',
+]
+
+if CONFIG['HAVE_LINUX_PERF_EVENT_H']:
+    SOURCES += [
+        'pm_linux.cpp'
+    ]
+    if CONFIG['LINUX_HEADERS_INCLUDES']:
+        SOURCES['pm_linux.cpp'].flags += [CONFIG['LINUX_HEADERS_INCLUDES']]
+else:
+    SOURCES += [
+        'pm_stub.cpp'
+    ]
\ No newline at end of file

From e6a6e0e7fd5db630c213f9beeb496ee895042c77 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 13:59:16 -0500
Subject: [PATCH 21/30] Issue #1676 - Part 14: Split proxy sources out of
 js/src/moz.build

---
 js/src/moz.build       |  9 +--------
 js/src/proxy/moz.build | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 8 deletions(-)
 create mode 100644 js/src/proxy/moz.build

diff --git a/js/src/moz.build b/js/src/moz.build
index 71147dc8d6..ceadfa3fd2 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -110,6 +110,7 @@ DIRS += [
     'irregexp',
     'jit',
     'perf',
+    'proxy',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -140,14 +141,6 @@ SOURCES += [
     'jsscript.cpp',
     'jsstr.cpp',
     'jsweakmap.cpp',
-    'proxy/BaseProxyHandler.cpp',
-    'proxy/CrossCompartmentWrapper.cpp',
-    'proxy/DeadObjectProxy.cpp',
-    'proxy/OpaqueCrossCompartmentWrapper.cpp',
-    'proxy/Proxy.cpp',
-    'proxy/ScriptedProxyHandler.cpp',
-    'proxy/SecurityWrapper.cpp',
-    'proxy/Wrapper.cpp',
     'threading/Mutex.cpp',
     'vm/ArgumentsObject.cpp',
     'vm/ArrayBufferObject.cpp',
diff --git a/js/src/proxy/moz.build b/js/src/proxy/moz.build
new file mode 100644
index 0000000000..72082df858
--- /dev/null
+++ b/js/src/proxy/moz.build
@@ -0,0 +1,23 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'BaseProxyHandler.cpp',
+    'CrossCompartmentWrapper.cpp',
+    'DeadObjectProxy.cpp',
+    'OpaqueCrossCompartmentWrapper.cpp',
+    'Proxy.cpp',
+    'ScriptedProxyHandler.cpp',
+    'SecurityWrapper.cpp',
+    'Wrapper.cpp',
+]

From 81d575eff776a6ffadb6b0f4760d3a83015fb2b7 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 14:11:22 -0500
Subject: [PATCH 22/30] Issue #1676 - Part 15: Split threading sources out of
 js/src/moz.build

---
 js/src/moz.build           | 17 ++---------------
 js/src/threading/moz.build | 30 ++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 15 deletions(-)
 create mode 100644 js/src/threading/moz.build

diff --git a/js/src/moz.build b/js/src/moz.build
index ceadfa3fd2..e7832709d8 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -11,6 +11,7 @@ CONFIGURE_SUBST_FILES += [
     'js-config',
     'js.pc',
 ]
+
 CONFIGURE_DEFINE_FILES += [
     'js-confdefs.h',
 ]
@@ -111,6 +112,7 @@ DIRS += [
     'jit',
     'perf',
     'proxy',
+    'threading',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -141,7 +143,6 @@ SOURCES += [
     'jsscript.cpp',
     'jsstr.cpp',
     'jsweakmap.cpp',
-    'threading/Mutex.cpp',
     'vm/ArgumentsObject.cpp',
     'vm/ArrayBufferObject.cpp',
     'vm/AsyncFunction.cpp',
@@ -256,20 +257,6 @@ if CONFIG['ENABLE_TRACE_LOGGING']:
         'vm/TraceLoggingTypes.cpp',
     ]
 
-if CONFIG['OS_ARCH'] == 'WINNT':
-    SOURCES += [
-        'threading/windows/ConditionVariable.cpp',
-        'threading/windows/MutexImpl.cpp',
-        'threading/windows/Thread.cpp',
-    ]
-    # _CRT_RAND_S must be #defined before #including stdlib.h to get rand_s()
-else:
-    SOURCES += [
-        'threading/posix/ConditionVariable.cpp',
-        'threading/posix/MutexImpl.cpp',
-        'threading/posix/Thread.cpp',
-    ]
-
 if CONFIG['JS_HAS_CTYPES']:
     SOURCES += [
         'ctypes/CTypes.cpp',
diff --git a/js/src/threading/moz.build b/js/src/threading/moz.build
new file mode 100644
index 0000000000..97673d0c62
--- /dev/null
+++ b/js/src/threading/moz.build
@@ -0,0 +1,30 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'Mutex.cpp',
+]
+
+if CONFIG['OS_ARCH'] == 'WINNT':
+    SOURCES += [
+        'windows/ConditionVariable.cpp',
+        'windows/MutexImpl.cpp',
+        'windows/Thread.cpp',
+    ]
+    # _CRT_RAND_S must be #defined before #including stdlib.h to get rand_s()
+else:
+    SOURCES += [
+        'posix/ConditionVariable.cpp',
+        'posix/MutexImpl.cpp',
+        'posix/Thread.cpp',
+    ]
\ No newline at end of file

From 6fa51e7392a383954aef947bc0905d4ee0fa6155 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 14:31:48 -0500
Subject: [PATCH 23/30] Issue #1676 - Part 16: Split WASM sources out of
 js/src/moz.build

Also puts WasmBinaryIterator.cpp which is debug code ifdef'd behind MOZ_DEBUG
---
 js/src/moz.build      | 23 +----------------------
 js/src/wasm/moz.build | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 22 deletions(-)
 create mode 100644 js/src/wasm/moz.build

diff --git a/js/src/moz.build b/js/src/moz.build
index e7832709d8..3c4093ade0 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -113,6 +113,7 @@ DIRS += [
     'perf',
     'proxy',
     'threading',
+    'wasm',
 ]
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -201,28 +202,6 @@ SOURCES += [
     'vm/Value.cpp',
     'vm/WeakMapPtr.cpp',
     'vm/Xdr.cpp',
-    'wasm/AsmJS.cpp',
-    'wasm/WasmBaselineCompile.cpp',
-    'wasm/WasmBinaryFormat.cpp',
-    'wasm/WasmBinaryIterator.cpp',
-    'wasm/WasmBinaryToAST.cpp',
-    'wasm/WasmBinaryToExperimentalText.cpp',
-    'wasm/WasmBinaryToText.cpp',
-    'wasm/WasmCode.cpp',
-    'wasm/WasmCompartment.cpp',
-    'wasm/WasmCompile.cpp',
-    'wasm/WasmFrameIterator.cpp',
-    'wasm/WasmGenerator.cpp',
-    'wasm/WasmInstance.cpp',
-    'wasm/WasmIonCompile.cpp',
-    'wasm/WasmJS.cpp',
-    'wasm/WasmModule.cpp',
-    'wasm/WasmSignalHandlers.cpp',
-    'wasm/WasmStubs.cpp',
-    'wasm/WasmTable.cpp',
-    'wasm/WasmTextToBinary.cpp',
-    'wasm/WasmTextUtils.cpp',
-    'wasm/WasmTypes.cpp'
 ]
 
 # jsarray.cpp and jsatom.cpp cannot be built in unified mode because
diff --git a/js/src/wasm/moz.build b/js/src/wasm/moz.build
new file mode 100644
index 0000000000..6a47df3229
--- /dev/null
+++ b/js/src/wasm/moz.build
@@ -0,0 +1,39 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'AsmJS.cpp',
+    'WasmBaselineCompile.cpp',
+    'WasmBinaryFormat.cpp',
+    'WasmBinaryToAST.cpp',
+    'WasmBinaryToExperimentalText.cpp',
+    'WasmBinaryToText.cpp',
+    'WasmCode.cpp',
+    'WasmCompartment.cpp',
+    'WasmCompile.cpp',
+    'WasmFrameIterator.cpp',
+    'WasmGenerator.cpp',
+    'WasmInstance.cpp',
+    'WasmIonCompile.cpp',
+    'WasmJS.cpp',
+    'WasmModule.cpp',
+    'WasmSignalHandlers.cpp',
+    'WasmStubs.cpp',
+    'WasmTable.cpp',
+    'WasmTextToBinary.cpp',
+    'WasmTextUtils.cpp',
+    'WasmTypes.cpp'
+]
+
+if CONFIG['MOZ_DEBUG']:
+    SOURCES += ['WasmBinaryIterator.cpp']
\ No newline at end of file

From fc371224e17471db3aec1234fa1c27de418540ac Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 14:38:12 -0500
Subject: [PATCH 24/30] Issue #1676 - Part 17: Put remaining source files which
 have debug code ifdef'd behind MOZ_DEBUG

---
 js/src/gc/moz.build  | 4 +++-
 js/src/jit/moz.build | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/js/src/gc/moz.build b/js/src/gc/moz.build
index 8f3188cf1f..d33dfb0079 100644
--- a/js/src/gc/moz.build
+++ b/js/src/gc/moz.build
@@ -24,6 +24,8 @@ SOURCES += [
     'Statistics.cpp',
     'StoreBuffer.cpp',
     'Tracer.cpp',
-    'Verifier.cpp',
     'Zone.cpp',
 ]
+
+if CONFIG['MOZ_DEBUG']:
+    SOURCES += ['Verifier.cpp']
diff --git a/js/src/jit/moz.build b/js/src/jit/moz.build
index bcd9b7dbf5..0c6c4f3b8c 100644
--- a/js/src/jit/moz.build
+++ b/js/src/jit/moz.build
@@ -32,7 +32,6 @@ SOURCES += [
     'CacheIR.cpp',
     'CodeGenerator.cpp',
     'CompileWrappers.cpp',
-    'Disassembler.cpp',
     'EagerSimdUnbox.cpp',
     'EdgeCaseAnalysis.cpp',
     'EffectiveAddressAnalysis.cpp',
@@ -83,6 +82,9 @@ SOURCES += [
     'WasmBCE.cpp',
 ]
 
+if CONFIG['MOZ_DEBUG']:
+    SOURCES += ['Disassembler.cpp']
+
 if not CONFIG['ENABLE_ION']:
     SOURCES += [
         'none/Trampoline-none.cpp'

From 66308991b11d1bd87dbd7e217749a31902626b08 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 14:45:57 -0500
Subject: [PATCH 25/30] Issue #1676 - Part 18: Move and separate top level
 sources from vm sources in js/src/moz.build

---
 js/src/moz.build | 39 ++++++++++++++-------------------------
 1 file changed, 14 insertions(+), 25 deletions(-)

diff --git a/js/src/moz.build b/js/src/moz.build
index 3c4093ade0..7b963ac425 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -125,15 +125,19 @@ if not CONFIG['JS_DISABLE_SHELL']:
 SOURCES += [
     'jsalloc.cpp',
     'jsapi.cpp',
+    'jsarray.cpp',
+    'jsatom.cpp',
     'jsbool.cpp',
     'jscntxt.cpp',
     'jscompartment.cpp',
     'jsdate.cpp',
+    'jsdtoa.cpp',
     'jsexn.cpp',
     'jsfriendapi.cpp',
     'jsfun.cpp',
     'jsgc.cpp',
     'jsiter.cpp',
+    'jsmath.cpp',
     'jsnativestack.cpp',
     'jsnum.cpp',
     'jsobj.cpp',
@@ -143,7 +147,16 @@ SOURCES += [
     'jspropertytree.cpp',
     'jsscript.cpp',
     'jsstr.cpp',
+    'jsutil.cpp',
     'jsweakmap.cpp',
+]
+
+# Suppress warnings in third-party code.
+# We are keeping this in the main moz.build because it is file specific
+if CONFIG['CLANG_CXX'] or CONFIG['GNU_CXX']:
+    SOURCES['jsdtoa.cpp'].flags += ['-Wno-implicit-fallthrough']
+
+SOURCES += [
     'vm/ArgumentsObject.cpp',
     'vm/ArrayBufferObject.cpp',
     'vm/AsyncFunction.cpp',
@@ -163,6 +176,7 @@ SOURCES += [
     'vm/GlobalObject.cpp',
     'vm/HelperThreads.cpp',
     'vm/Id.cpp',
+    'vm/Initialization.cpp',
     'vm/Interpreter.cpp',
     'vm/JSONParser.cpp',
     'vm/MemoryMetrics.cpp',
@@ -204,26 +218,6 @@ SOURCES += [
     'vm/Xdr.cpp',
 ]
 
-# jsarray.cpp and jsatom.cpp cannot be built in unified mode because
-# xpcshell is broken during packaging when compiled with gcc-4.8.2
-# jsdtoa.cpp cannot be built in unified mode because we want to suppress
-# compiler warnings in third-party dtoa.c.
-# jsmath.cpp cannot be built in unified mode because it needs to pull rand_s
-# from <stdlib.h> on Windows through a preprocessor define.
-# jsutil.cpp cannot be built in unified mode because it is needed for
-# check-vanilla-allocations.
-# StoreBuffer.cpp cannot be built in unified because its template
-# instantiations may or may not be needed depending on what it gets bundled
-# with.
-SOURCES += [
-    'jsarray.cpp',
-    'jsatom.cpp',
-    'jsdtoa.cpp',
-    'jsmath.cpp',
-    'jsutil.cpp',
-    'vm/Initialization.cpp',
-]
-
 if CONFIG['JS_POSIX_NSPR']:
     SOURCES += [
         'vm/PosixNSPR.cpp',
@@ -315,9 +309,4 @@ NO_EXPAND_LIBS = True
 
 DIST_INSTALL = True
 
-# Suppress warnings in third-party code.
-# We are keeping this in the main moz.build because it is file specific
-if CONFIG['CLANG_CXX'] or CONFIG['GNU_CXX']:
-    SOURCES['jsdtoa.cpp'].flags += ['-Wno-implicit-fallthrough']
-
 

From 6da35ffb78c049463c023a2d9e694ccca6cc71d4 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 14:59:00 -0500
Subject: [PATCH 26/30] Issue #1676 - Part 19: Split ctypes sources out of
 js/src/moz.build

---
 js/src/ctypes/moz.build | 26 ++++++++++++++++++++++++++
 js/src/moz.build        | 19 +++----------------
 2 files changed, 29 insertions(+), 16 deletions(-)
 create mode 100644 js/src/ctypes/moz.build

diff --git a/js/src/ctypes/moz.build b/js/src/ctypes/moz.build
new file mode 100644
index 0000000000..5bea399f37
--- /dev/null
+++ b/js/src/ctypes/moz.build
@@ -0,0 +1,26 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'CTypes.cpp',
+    'Library.cpp',
+]
+
+if not CONFIG['MOZ_SYSTEM_FFI']:
+    LOCAL_INCLUDES += [
+        '!libffi/include',
+        'libffi/src/%s' % CONFIG['FFI_TARGET_DIR'],
+    ]
+
+if CONFIG['_MSC_VER'] and CONFIG['CPU_ARCH'] == 'x86_64':
+    SOURCES['CTypes.cpp'].no_pgo = True # Bug 810661
\ No newline at end of file
diff --git a/js/src/moz.build b/js/src/moz.build
index 7b963ac425..20c1e57226 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -122,6 +122,9 @@ if CONFIG['JS_BUNDLED_EDITLINE']:
 if not CONFIG['JS_DISABLE_SHELL']:
     DIRS += ['shell']
 
+if CONFIG['JS_HAS_CTYPES']:
+    DIRS += ['ctypes']
+
 SOURCES += [
     'jsalloc.cpp',
     'jsapi.cpp',
@@ -230,17 +233,6 @@ if CONFIG['ENABLE_TRACE_LOGGING']:
         'vm/TraceLoggingTypes.cpp',
     ]
 
-if CONFIG['JS_HAS_CTYPES']:
-    SOURCES += [
-        'ctypes/CTypes.cpp',
-        'ctypes/Library.cpp',
-    ]
-    if not CONFIG['MOZ_SYSTEM_FFI']:
-        LOCAL_INCLUDES += [
-            '!ctypes/libffi/include',
-            'ctypes/libffi/src/%s' % CONFIG['FFI_TARGET_DIR'],
-        ]
-
 if CONFIG['MOZ_VTUNE']:
     SOURCES += [
         'vtune/jitprofiling.c'
@@ -281,11 +273,6 @@ USE_LIBS += [
     'zlib',
 ]
 
-
-if CONFIG['_MSC_VER']:
-    if CONFIG['CPU_ARCH'] == 'x86_64' and CONFIG['JS_HAS_CTYPES']:
-        SOURCES['ctypes/CTypes.cpp'].no_pgo = True # Bug 810661
-
 if CONFIG['OS_ARCH'] not in ('WINNT'):
     OS_LIBS += ['m']
 

From b38a25013058a0df0c45206c8aee9128c6ed96a1 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 15:03:13 -0500
Subject: [PATCH 27/30] Issue #1676 - Part 20: Split vtune sources out of
 js/src/moz.build

---
 js/src/moz.build       | 12 +++++-------
 js/src/vtune/moz.build | 14 ++++++++++++++
 2 files changed, 19 insertions(+), 7 deletions(-)
 create mode 100644 js/src/vtune/moz.build

diff --git a/js/src/moz.build b/js/src/moz.build
index 20c1e57226..f9e5233a9f 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -116,14 +116,17 @@ DIRS += [
     'wasm',
 ]
 
+if CONFIG['JS_HAS_CTYPES']:
+    DIRS += ['ctypes']
+
 if CONFIG['JS_BUNDLED_EDITLINE']:
     DIRS += ['editline']
 
 if not CONFIG['JS_DISABLE_SHELL']:
     DIRS += ['shell']
 
-if CONFIG['JS_HAS_CTYPES']:
-    DIRS += ['ctypes']
+if CONFIG['MOZ_VTUNE']:
+    DIRS += ['vtune']
 
 SOURCES += [
     'jsalloc.cpp',
@@ -233,11 +236,6 @@ if CONFIG['ENABLE_TRACE_LOGGING']:
         'vm/TraceLoggingTypes.cpp',
     ]
 
-if CONFIG['MOZ_VTUNE']:
-    SOURCES += [
-        'vtune/jitprofiling.c'
-    ]
-
 # JavaScript must be built shared, even for static builds, as it is used by
 # other modules which are always built shared. Failure to do so results in
 # the js code getting copied into xpinstall and jsd as well as mozilla-bin,
diff --git a/js/src/vtune/moz.build b/js/src/vtune/moz.build
new file mode 100644
index 0000000000..4659197958
--- /dev/null
+++ b/js/src/vtune/moz.build
@@ -0,0 +1,14 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += ['jitprofiling.c']
\ No newline at end of file

From 5f32ee0c7154c3e435fe9fcebc8a2e6b656ca32d Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 16:24:38 -0500
Subject: [PATCH 28/30] Issue #1676 - Part 21: Use js-cxxflags.mozbuild in
 testing code and js shell

---
 js/src/gdb/moz.build         | 9 ++-------
 js/src/jsapi-tests/moz.build | 9 ++-------
 js/src/shell/moz.build       | 9 ++-------
 3 files changed, 6 insertions(+), 21 deletions(-)

diff --git a/js/src/gdb/moz.build b/js/src/gdb/moz.build
index a2e9356242..01f6cb0b64 100644
--- a/js/src/gdb/moz.build
+++ b/js/src/gdb/moz.build
@@ -5,6 +5,8 @@
 
 GeckoProgram('gdb-tests', linkage=None)
 
+include('../js-cxxflags.mozbuild')
+
 UNIFIED_SOURCES += [
     'gdb-tests.cpp',
     'tests/test-asmjs.cpp',
@@ -40,13 +42,6 @@ if CONFIG['MOZ_ICU_DATA_ARCHIVE']:
 
 OS_LIBS += CONFIG['MOZ_ZLIB_LIBS']
 
-if CONFIG['GNU_CXX']:
-    CXXFLAGS += ['-Wno-shadow', '-fno-strict-aliasing']
-
-# This is intended as a temporary workaround to enable VS2015.
-if CONFIG['_MSC_VER']:
-    CXXFLAGS += ['-wd4312']
-
 DEFINES['topsrcdir'] = '%s/js/src' % TOPSRCDIR
 FINAL_TARGET_PP_FILES += ['gdb-tests-gdb.py.in']
 OBJDIR_FILES.js.src.gdb += ['!/dist/bin/gdb-tests-gdb.py']
diff --git a/js/src/jsapi-tests/moz.build b/js/src/jsapi-tests/moz.build
index 378b2ed7fa..35bc69b85b 100644
--- a/js/src/jsapi-tests/moz.build
+++ b/js/src/jsapi-tests/moz.build
@@ -3,6 +3,8 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+include(../js-cxxflags.mozbuild)
+
 GeckoProgram('jsapi-tests', linkage=None)
 
 UNIFIED_SOURCES += [
@@ -142,12 +144,5 @@ USE_LIBS += [
 
 OS_LIBS += CONFIG['MOZ_ZLIB_LIBS']
 
-if CONFIG['GNU_CXX']:
-    CXXFLAGS += ['-Wno-shadow', '-Werror=format', '-fno-strict-aliasing']
-
-# This is intended as a temporary workaround to enable VS2015.
-if CONFIG['_MSC_VER']:
-    CXXFLAGS += ['-wd4312']
-
 DEFINES['topsrcdir'] = '%s/js/src' % TOPSRCDIR
 OBJDIR_PP_FILES.js.src['jsapi-tests'] += ['jsapi-tests-gdb.py.in']
diff --git a/js/src/shell/moz.build b/js/src/shell/moz.build
index 7c861fb0d6..93812da74a 100644
--- a/js/src/shell/moz.build
+++ b/js/src/shell/moz.build
@@ -3,6 +3,8 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+include('../js-cxxflags.mozbuild')
+
 if CONFIG['JS_SHELL_NAME']:
     GeckoProgram(CONFIG['JS_SHELL_NAME'], linkage=None)
     if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -49,13 +51,6 @@ shellmoduleloader.inputs = [
     'ModuleLoader.js',
 ]
 
-if CONFIG['GNU_CXX']:
-    CXXFLAGS += ['-Wno-shadow', '-Werror=format']
-
-# This is intended as a temporary workaround to enable VS2015.
-if CONFIG['_MSC_VER']:
-    CXXFLAGS += ['-wd4312']
-
 # Place a GDB Python auto-load file next to the shell executable, both in
 # the build directory and in the dist/bin directory.
 DEFINES['topsrcdir'] = '%s/js/src' % TOPSRCDIR

From 6dc6ff456e6da315589cf68f8b68271fc7c00b9d Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 19:46:11 -0500
Subject: [PATCH 29/30] Issue #1677 - Part 1: Import new V8 regexp code with
 Mozilla's header modifications

---
 js/src/regexp/VERSION                         |    3 +
 js/src/regexp/gen-regexp-special-case.cc      |  124 +
 js/src/regexp/property-sequences.cc           | 1246 ++++++
 js/src/regexp/property-sequences.h            |   26 +
 js/src/regexp/regexp-ast.cc                   |  342 ++
 js/src/regexp/regexp-ast.h                    |  599 +++
 js/src/regexp/regexp-bytecode-generator-inl.h |   55 +
 js/src/regexp/regexp-bytecode-generator.cc    |  397 ++
 js/src/regexp/regexp-bytecode-generator.h     |  119 +
 js/src/regexp/regexp-bytecode-peephole.cc     | 1029 +++++
 js/src/regexp/regexp-bytecode-peephole.h      |   29 +
 js/src/regexp/regexp-bytecodes.cc             |   45 +
 js/src/regexp/regexp-bytecodes.h              |  250 ++
 js/src/regexp/regexp-compiler-tonode.cc       | 1675 +++++++
 js/src/regexp/regexp-compiler.cc              | 3834 +++++++++++++++++
 js/src/regexp/regexp-compiler.h               |  625 +++
 js/src/regexp/regexp-dotprinter.cc            |  252 ++
 js/src/regexp/regexp-dotprinter.h             |   22 +
 js/src/regexp/regexp-interpreter.cc           | 1053 +++++
 js/src/regexp/regexp-interpreter.h            |   61 +
 .../regexp/regexp-macro-assembler-tracer.cc   |  420 ++
 js/src/regexp/regexp-macro-assembler-tracer.h |   81 +
 js/src/regexp/regexp-macro-assembler.cc       |  367 ++
 js/src/regexp/regexp-macro-assembler.h        |  277 ++
 js/src/regexp/regexp-nodes.h                  |  750 ++++
 js/src/regexp/regexp-parser.cc                | 2115 +++++++++
 js/src/regexp/regexp-parser.h                 |  359 ++
 js/src/regexp/regexp-stack.cc                 |   97 +
 js/src/regexp/regexp-stack.h                  |  140 +
 js/src/regexp/regexp.h                        |  189 +
 js/src/regexp/special-case.h                  |   79 +
 js/src/regexp/update-headers.py               |   38 +
 32 files changed, 16698 insertions(+)
 create mode 100644 js/src/regexp/VERSION
 create mode 100644 js/src/regexp/gen-regexp-special-case.cc
 create mode 100644 js/src/regexp/property-sequences.cc
 create mode 100644 js/src/regexp/property-sequences.h
 create mode 100644 js/src/regexp/regexp-ast.cc
 create mode 100644 js/src/regexp/regexp-ast.h
 create mode 100644 js/src/regexp/regexp-bytecode-generator-inl.h
 create mode 100644 js/src/regexp/regexp-bytecode-generator.cc
 create mode 100644 js/src/regexp/regexp-bytecode-generator.h
 create mode 100644 js/src/regexp/regexp-bytecode-peephole.cc
 create mode 100644 js/src/regexp/regexp-bytecode-peephole.h
 create mode 100644 js/src/regexp/regexp-bytecodes.cc
 create mode 100644 js/src/regexp/regexp-bytecodes.h
 create mode 100644 js/src/regexp/regexp-compiler-tonode.cc
 create mode 100644 js/src/regexp/regexp-compiler.cc
 create mode 100644 js/src/regexp/regexp-compiler.h
 create mode 100644 js/src/regexp/regexp-dotprinter.cc
 create mode 100644 js/src/regexp/regexp-dotprinter.h
 create mode 100644 js/src/regexp/regexp-interpreter.cc
 create mode 100644 js/src/regexp/regexp-interpreter.h
 create mode 100644 js/src/regexp/regexp-macro-assembler-tracer.cc
 create mode 100644 js/src/regexp/regexp-macro-assembler-tracer.h
 create mode 100644 js/src/regexp/regexp-macro-assembler.cc
 create mode 100644 js/src/regexp/regexp-macro-assembler.h
 create mode 100644 js/src/regexp/regexp-nodes.h
 create mode 100644 js/src/regexp/regexp-parser.cc
 create mode 100644 js/src/regexp/regexp-parser.h
 create mode 100644 js/src/regexp/regexp-stack.cc
 create mode 100644 js/src/regexp/regexp-stack.h
 create mode 100644 js/src/regexp/regexp.h
 create mode 100644 js/src/regexp/special-case.h
 create mode 100644 js/src/regexp/update-headers.py

diff --git a/js/src/regexp/VERSION b/js/src/regexp/VERSION
new file mode 100644
index 0000000000..3a0935deac
--- /dev/null
+++ b/js/src/regexp/VERSION
@@ -0,0 +1,3 @@
+This code was most recently imported from the following version of V8:
+
+https://github.com/v8/v8/tree/2599d3cc208a3a4873be517285220abd8416c3d7/src/regexp
diff --git a/js/src/regexp/gen-regexp-special-case.cc b/js/src/regexp/gen-regexp-special-case.cc
new file mode 100644
index 0000000000..337743f536
--- /dev/null
+++ b/js/src/regexp/gen-regexp-special-case.cc
@@ -0,0 +1,124 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <fstream>
+#include <iomanip>
+#include <iostream>
+#include <sstream>
+
+#include "unicode/uchar.h"
+#include "unicode/uniset.h"
+
+namespace v8 {
+namespace internal {
+
+// The following code generates BuildSpecialAddSet() and BuildIgnoreSet()
+// functions into "src/regexp/special-case.cc".
+// See more details in http://shorturl.at/adfO5
+void PrintSet(std::ofstream& out, const char* func_name,
+              const icu::UnicodeSet& set) {
+  out << "icu::UnicodeSet " << func_name << "() {\n"
+      << "  icu::UnicodeSet set;\n";
+  for (int32_t i = 0; i < set.getRangeCount(); i++) {
+    if (set.getRangeStart(i) == set.getRangeEnd(i)) {
+      out << "  set.add(0x" << set.getRangeStart(i) << ");\n";
+    } else {
+      out << "  set.add(0x" << set.getRangeStart(i) << ", 0x"
+          << set.getRangeEnd(i) << ");\n";
+    }
+  }
+  out << "  set.freeze();\n"
+      << "  return set;\n"
+      << "}\n";
+}
+
+void PrintSpecial(std::ofstream& out) {
+  icu::UnicodeSet current;
+  icu::UnicodeSet processed(0xd800, 0xdbff);  // Ignore surrogate range.
+  icu::UnicodeSet special_add;
+  icu::UnicodeSet ignore;
+  UErrorCode status = U_ZERO_ERROR;
+  icu::UnicodeSet upper("[\\p{Lu}]", status);
+  CHECK(U_SUCCESS(status));
+  // Iterate through all chars in BMP except ASCII and Surrogate.
+  for (UChar32 i = 0x80; i < 0x010000; i++) {
+    // Ignore those characters which is already processed.
+    if (!processed.contains(i)) {
+      current.set(i, i);
+      current.closeOver(USET_CASE_INSENSITIVE);
+
+      // Remember we already processed current.
+      processed.addAll(current);
+
+      // All uppercase characters in current.
+      icu::UnicodeSet keep_upper(current);
+      keep_upper.retainAll(upper);
+
+      // Check if we have more than one uppercase character in current.
+      // If there are more than one uppercase character, then it is a special
+      // set which need to be added into either "Special Add" set or "Ignore"
+      // set.
+      int32_t number_of_upper = 0;
+      for (int32_t i = 0; i < keep_upper.getRangeCount() && i <= 1; i++) {
+        number_of_upper +=
+            keep_upper.getRangeEnd(i) - keep_upper.getRangeStart(i) + 1;
+      }
+      if (number_of_upper > 1) {
+        // Add all non uppercase characters (could be Ll or Mn) to special add
+        // set.
+        current.removeAll(upper);
+        special_add.addAll(current);
+
+        // Add the uppercase characters of non uppercase character to
+        // special add set.
+        CHECK_GT(current.getRangeCount(), 0);
+        UChar32 main_upper = u_toupper(current.getRangeStart(0));
+        special_add.add(main_upper);
+
+        // Add all uppercase except the main upper to ignore set.
+        keep_upper.remove(main_upper);
+        ignore.addAll(keep_upper);
+      }
+    }
+  }
+
+  // Remove any ASCII
+  special_add.remove(0x0000, 0x007f);
+  PrintSet(out, "BuildIgnoreSet", ignore);
+  PrintSet(out, "BuildSpecialAddSet", special_add);
+}
+
+void WriteHeader(const char* header_filename) {
+  std::ofstream out(header_filename);
+  out << std::hex << std::setfill('0') << std::setw(4);
+
+  out << "// Automatically generated by regexp/gen-regexp-special-case.cc\n"
+      << "// The following functions are used to build icu::UnicodeSet\n"
+      << "// for specical cases different between Unicode and ECMA262.\n"
+      << "#ifdef V8_INTL_SUPPORT\n"
+      << "#include \"src/regexp/special-case.h\"\n\n"
+      << "#include \"unicode/uniset.h\"\n"
+      << "namespace v8 {\n"
+      << "namespace internal {\n\n";
+
+  PrintSpecial(out);
+
+  out << "\n"
+      << "}  // namespace internal\n"
+      << "}  // namespace v8\n"
+      << "#endif  // V8_INTL_SUPPORT\n";
+}
+
+}  // namespace internal
+}  // namespace v8
+
+int main(int argc, const char** argv) {
+  if (argc != 2) {
+    std::cerr << "Usage: " << argv[0] << " <output filename>\n";
+    std::exit(1);
+  }
+  v8::internal::WriteHeader(argv[1]);
+
+  return 0;
+}
diff --git a/js/src/regexp/property-sequences.cc b/js/src/regexp/property-sequences.cc
new file mode 100644
index 0000000000..e07d6da531
--- /dev/null
+++ b/js/src/regexp/property-sequences.cc
@@ -0,0 +1,1246 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifdef V8_INTL_SUPPORT
+
+#include "regexp/property-sequences.h"
+
+namespace v8 {
+namespace internal {
+
+/*
+Generated from following Node.js source:
+
+package.json
+
+```
+{
+  "private": true,
+  "dependencies": {
+    "unicode-12.0.0": "^0.7.9"
+  }
+}
+```
+
+generate-unicode-sequence-property-data.js
+
+```
+const toHex = (symbol) => {
+  return '0x' + symbol.codePointAt(0).toString(16)
+                      .toUpperCase().padStart(6, '0');
+};
+
+const generateData = (property) => {
+  const sequences =
+      require(`unicode-12.0.0/Sequence_Property/${ property }/index.js`);
+  const id = property.replace(/_/g, '') + 's';
+  const buffer = [];
+  for (const sequence of sequences) {
+    const symbols = [...sequence];
+    const codePoints = symbols.map(symbol => toHex(symbol));
+    buffer.push('    ' + codePoints.join(', ') + ', 0,');
+  }
+  const output =
+      `const uc32 UnicodePropertySequences::k${ id }[] = {\n` +
+      `${ buffer.join('\n') }\n    0  // null-terminating the list\n};\n`;
+  return output;
+};
+
+const properties = [
+  'Emoji_Flag_Sequence',
+  'Emoji_Tag_Sequence',
+  'Emoji_ZWJ_Sequence',
+];
+
+for (const property of properties) {
+  console.log(generateData(property));
+}
+```
+*/
+
+// clang-format off
+const uc32 UnicodePropertySequences::kEmojiFlagSequences[] = {
+    0x01F1E6, 0x01F1E8, 0,
+    0x01F1FF, 0x01F1FC, 0,
+    0x01F1E6, 0x01F1EA, 0,
+    0x01F1E6, 0x01F1EB, 0,
+    0x01F1E6, 0x01F1EC, 0,
+    0x01F1E6, 0x01F1EE, 0,
+    0x01F1E6, 0x01F1F1, 0,
+    0x01F1E6, 0x01F1F2, 0,
+    0x01F1E6, 0x01F1F4, 0,
+    0x01F1E6, 0x01F1F6, 0,
+    0x01F1E6, 0x01F1F7, 0,
+    0x01F1E6, 0x01F1F8, 0,
+    0x01F1E6, 0x01F1F9, 0,
+    0x01F1E6, 0x01F1FA, 0,
+    0x01F1E6, 0x01F1FC, 0,
+    0x01F1E6, 0x01F1FD, 0,
+    0x01F1E6, 0x01F1FF, 0,
+    0x01F1E7, 0x01F1E6, 0,
+    0x01F1E7, 0x01F1E7, 0,
+    0x01F1E7, 0x01F1E9, 0,
+    0x01F1E7, 0x01F1EA, 0,
+    0x01F1E7, 0x01F1EB, 0,
+    0x01F1E7, 0x01F1EC, 0,
+    0x01F1E7, 0x01F1ED, 0,
+    0x01F1E7, 0x01F1EE, 0,
+    0x01F1E7, 0x01F1EF, 0,
+    0x01F1E7, 0x01F1F1, 0,
+    0x01F1E7, 0x01F1F2, 0,
+    0x01F1E7, 0x01F1F3, 0,
+    0x01F1E7, 0x01F1F4, 0,
+    0x01F1E7, 0x01F1F6, 0,
+    0x01F1E7, 0x01F1F7, 0,
+    0x01F1E7, 0x01F1F8, 0,
+    0x01F1E7, 0x01F1F9, 0,
+    0x01F1E7, 0x01F1FB, 0,
+    0x01F1E7, 0x01F1FC, 0,
+    0x01F1E7, 0x01F1FE, 0,
+    0x01F1E7, 0x01F1FF, 0,
+    0x01F1E8, 0x01F1E6, 0,
+    0x01F1E8, 0x01F1E8, 0,
+    0x01F1E8, 0x01F1E9, 0,
+    0x01F1E8, 0x01F1EB, 0,
+    0x01F1E8, 0x01F1EC, 0,
+    0x01F1E8, 0x01F1ED, 0,
+    0x01F1E8, 0x01F1EE, 0,
+    0x01F1E8, 0x01F1F0, 0,
+    0x01F1E8, 0x01F1F1, 0,
+    0x01F1E8, 0x01F1F2, 0,
+    0x01F1E8, 0x01F1F3, 0,
+    0x01F1E8, 0x01F1F4, 0,
+    0x01F1E8, 0x01F1F5, 0,
+    0x01F1E8, 0x01F1F7, 0,
+    0x01F1E8, 0x01F1FA, 0,
+    0x01F1E8, 0x01F1FB, 0,
+    0x01F1E8, 0x01F1FC, 0,
+    0x01F1E8, 0x01F1FD, 0,
+    0x01F1E8, 0x01F1FE, 0,
+    0x01F1E8, 0x01F1FF, 0,
+    0x01F1E9, 0x01F1EA, 0,
+    0x01F1E9, 0x01F1EC, 0,
+    0x01F1E9, 0x01F1EF, 0,
+    0x01F1E9, 0x01F1F0, 0,
+    0x01F1E9, 0x01F1F2, 0,
+    0x01F1E9, 0x01F1F4, 0,
+    0x01F1E9, 0x01F1FF, 0,
+    0x01F1EA, 0x01F1E6, 0,
+    0x01F1EA, 0x01F1E8, 0,
+    0x01F1EA, 0x01F1EA, 0,
+    0x01F1EA, 0x01F1EC, 0,
+    0x01F1EA, 0x01F1ED, 0,
+    0x01F1EA, 0x01F1F7, 0,
+    0x01F1EA, 0x01F1F8, 0,
+    0x01F1EA, 0x01F1F9, 0,
+    0x01F1EA, 0x01F1FA, 0,
+    0x01F1EB, 0x01F1EE, 0,
+    0x01F1EB, 0x01F1EF, 0,
+    0x01F1EB, 0x01F1F0, 0,
+    0x01F1EB, 0x01F1F2, 0,
+    0x01F1EB, 0x01F1F4, 0,
+    0x01F1EB, 0x01F1F7, 0,
+    0x01F1EC, 0x01F1E6, 0,
+    0x01F1EC, 0x01F1E7, 0,
+    0x01F1EC, 0x01F1E9, 0,
+    0x01F1EC, 0x01F1EA, 0,
+    0x01F1EC, 0x01F1EB, 0,
+    0x01F1EC, 0x01F1EC, 0,
+    0x01F1EC, 0x01F1ED, 0,
+    0x01F1EC, 0x01F1EE, 0,
+    0x01F1EC, 0x01F1F1, 0,
+    0x01F1EC, 0x01F1F2, 0,
+    0x01F1EC, 0x01F1F3, 0,
+    0x01F1EC, 0x01F1F5, 0,
+    0x01F1EC, 0x01F1F6, 0,
+    0x01F1EC, 0x01F1F7, 0,
+    0x01F1EC, 0x01F1F8, 0,
+    0x01F1EC, 0x01F1F9, 0,
+    0x01F1EC, 0x01F1FA, 0,
+    0x01F1EC, 0x01F1FC, 0,
+    0x01F1EC, 0x01F1FE, 0,
+    0x01F1ED, 0x01F1F0, 0,
+    0x01F1ED, 0x01F1F2, 0,
+    0x01F1ED, 0x01F1F3, 0,
+    0x01F1ED, 0x01F1F7, 0,
+    0x01F1ED, 0x01F1F9, 0,
+    0x01F1ED, 0x01F1FA, 0,
+    0x01F1EE, 0x01F1E8, 0,
+    0x01F1EE, 0x01F1E9, 0,
+    0x01F1EE, 0x01F1EA, 0,
+    0x01F1EE, 0x01F1F1, 0,
+    0x01F1EE, 0x01F1F2, 0,
+    0x01F1EE, 0x01F1F3, 0,
+    0x01F1EE, 0x01F1F4, 0,
+    0x01F1EE, 0x01F1F6, 0,
+    0x01F1EE, 0x01F1F7, 0,
+    0x01F1EE, 0x01F1F8, 0,
+    0x01F1EE, 0x01F1F9, 0,
+    0x01F1EF, 0x01F1EA, 0,
+    0x01F1EF, 0x01F1F2, 0,
+    0x01F1EF, 0x01F1F4, 0,
+    0x01F1EF, 0x01F1F5, 0,
+    0x01F1F0, 0x01F1EA, 0,
+    0x01F1F0, 0x01F1EC, 0,
+    0x01F1F0, 0x01F1ED, 0,
+    0x01F1F0, 0x01F1EE, 0,
+    0x01F1F0, 0x01F1F2, 0,
+    0x01F1F0, 0x01F1F3, 0,
+    0x01F1F0, 0x01F1F5, 0,
+    0x01F1F0, 0x01F1F7, 0,
+    0x01F1F0, 0x01F1FC, 0,
+    0x01F1E6, 0x01F1E9, 0,
+    0x01F1F0, 0x01F1FF, 0,
+    0x01F1F1, 0x01F1E6, 0,
+    0x01F1F1, 0x01F1E7, 0,
+    0x01F1F1, 0x01F1E8, 0,
+    0x01F1F1, 0x01F1EE, 0,
+    0x01F1F1, 0x01F1F0, 0,
+    0x01F1F1, 0x01F1F7, 0,
+    0x01F1F1, 0x01F1F8, 0,
+    0x01F1F1, 0x01F1F9, 0,
+    0x01F1F1, 0x01F1FA, 0,
+    0x01F1F1, 0x01F1FB, 0,
+    0x01F1F1, 0x01F1FE, 0,
+    0x01F1F2, 0x01F1E6, 0,
+    0x01F1F2, 0x01F1E8, 0,
+    0x01F1F2, 0x01F1E9, 0,
+    0x01F1F2, 0x01F1EA, 0,
+    0x01F1F2, 0x01F1EB, 0,
+    0x01F1F2, 0x01F1EC, 0,
+    0x01F1F2, 0x01F1ED, 0,
+    0x01F1F2, 0x01F1F0, 0,
+    0x01F1F2, 0x01F1F1, 0,
+    0x01F1F2, 0x01F1F2, 0,
+    0x01F1F2, 0x01F1F3, 0,
+    0x01F1F2, 0x01F1F4, 0,
+    0x01F1F2, 0x01F1F5, 0,
+    0x01F1F2, 0x01F1F6, 0,
+    0x01F1F2, 0x01F1F7, 0,
+    0x01F1F2, 0x01F1F8, 0,
+    0x01F1F2, 0x01F1F9, 0,
+    0x01F1F2, 0x01F1FA, 0,
+    0x01F1F2, 0x01F1FB, 0,
+    0x01F1F2, 0x01F1FC, 0,
+    0x01F1F2, 0x01F1FD, 0,
+    0x01F1F2, 0x01F1FE, 0,
+    0x01F1F2, 0x01F1FF, 0,
+    0x01F1F3, 0x01F1E6, 0,
+    0x01F1F3, 0x01F1E8, 0,
+    0x01F1F3, 0x01F1EA, 0,
+    0x01F1F3, 0x01F1EB, 0,
+    0x01F1F3, 0x01F1EC, 0,
+    0x01F1F3, 0x01F1EE, 0,
+    0x01F1F3, 0x01F1F1, 0,
+    0x01F1F3, 0x01F1F4, 0,
+    0x01F1F3, 0x01F1F5, 0,
+    0x01F1F3, 0x01F1F7, 0,
+    0x01F1F3, 0x01F1FA, 0,
+    0x01F1F3, 0x01F1FF, 0,
+    0x01F1F4, 0x01F1F2, 0,
+    0x01F1F5, 0x01F1E6, 0,
+    0x01F1F5, 0x01F1EA, 0,
+    0x01F1F5, 0x01F1EB, 0,
+    0x01F1F5, 0x01F1EC, 0,
+    0x01F1F5, 0x01F1ED, 0,
+    0x01F1F5, 0x01F1F0, 0,
+    0x01F1F5, 0x01F1F1, 0,
+    0x01F1F5, 0x01F1F2, 0,
+    0x01F1F5, 0x01F1F3, 0,
+    0x01F1F5, 0x01F1F7, 0,
+    0x01F1F5, 0x01F1F8, 0,
+    0x01F1F5, 0x01F1F9, 0,
+    0x01F1F5, 0x01F1FC, 0,
+    0x01F1F5, 0x01F1FE, 0,
+    0x01F1F6, 0x01F1E6, 0,
+    0x01F1F7, 0x01F1EA, 0,
+    0x01F1F7, 0x01F1F4, 0,
+    0x01F1F7, 0x01F1F8, 0,
+    0x01F1F7, 0x01F1FA, 0,
+    0x01F1F7, 0x01F1FC, 0,
+    0x01F1F8, 0x01F1E6, 0,
+    0x01F1F8, 0x01F1E7, 0,
+    0x01F1F8, 0x01F1E8, 0,
+    0x01F1F8, 0x01F1E9, 0,
+    0x01F1F8, 0x01F1EA, 0,
+    0x01F1F8, 0x01F1EC, 0,
+    0x01F1F8, 0x01F1ED, 0,
+    0x01F1F8, 0x01F1EE, 0,
+    0x01F1F8, 0x01F1EF, 0,
+    0x01F1F8, 0x01F1F0, 0,
+    0x01F1F8, 0x01F1F1, 0,
+    0x01F1F8, 0x01F1F2, 0,
+    0x01F1F8, 0x01F1F3, 0,
+    0x01F1F8, 0x01F1F4, 0,
+    0x01F1F8, 0x01F1F7, 0,
+    0x01F1F8, 0x01F1F8, 0,
+    0x01F1F8, 0x01F1F9, 0,
+    0x01F1F8, 0x01F1FB, 0,
+    0x01F1F8, 0x01F1FD, 0,
+    0x01F1F8, 0x01F1FE, 0,
+    0x01F1F8, 0x01F1FF, 0,
+    0x01F1F9, 0x01F1E6, 0,
+    0x01F1F9, 0x01F1E8, 0,
+    0x01F1F9, 0x01F1E9, 0,
+    0x01F1F9, 0x01F1EB, 0,
+    0x01F1F9, 0x01F1EC, 0,
+    0x01F1F9, 0x01F1ED, 0,
+    0x01F1F9, 0x01F1EF, 0,
+    0x01F1F9, 0x01F1F0, 0,
+    0x01F1F9, 0x01F1F1, 0,
+    0x01F1F9, 0x01F1F2, 0,
+    0x01F1F9, 0x01F1F3, 0,
+    0x01F1F9, 0x01F1F4, 0,
+    0x01F1F9, 0x01F1F7, 0,
+    0x01F1F9, 0x01F1F9, 0,
+    0x01F1F9, 0x01F1FB, 0,
+    0x01F1F9, 0x01F1FC, 0,
+    0x01F1F9, 0x01F1FF, 0,
+    0x01F1FA, 0x01F1E6, 0,
+    0x01F1FA, 0x01F1EC, 0,
+    0x01F1FA, 0x01F1F2, 0,
+    0x01F1FA, 0x01F1F3, 0,
+    0x01F1FA, 0x01F1F8, 0,
+    0x01F1FA, 0x01F1FE, 0,
+    0x01F1FA, 0x01F1FF, 0,
+    0x01F1FB, 0x01F1E6, 0,
+    0x01F1FB, 0x01F1E8, 0,
+    0x01F1FB, 0x01F1EA, 0,
+    0x01F1FB, 0x01F1EC, 0,
+    0x01F1FB, 0x01F1EE, 0,
+    0x01F1FB, 0x01F1F3, 0,
+    0x01F1FB, 0x01F1FA, 0,
+    0x01F1FC, 0x01F1EB, 0,
+    0x01F1FC, 0x01F1F8, 0,
+    0x01F1FD, 0x01F1F0, 0,
+    0x01F1FE, 0x01F1EA, 0,
+    0x01F1FE, 0x01F1F9, 0,
+    0x01F1FF, 0x01F1E6, 0,
+    0x01F1FF, 0x01F1F2, 0,
+    0x01F1F0, 0x01F1FE, 0,
+    0  // null-terminating the list
+};
+
+const uc32 UnicodePropertySequences::kEmojiTagSequences[] = {
+    0x01F3F4, 0x0E0067, 0x0E0062, 0x0E0065, 0x0E006E, 0x0E0067, 0x0E007F, 0,
+    0x01F3F4, 0x0E0067, 0x0E0062, 0x0E0073, 0x0E0063, 0x0E0074, 0x0E007F, 0,
+    0x01F3F4, 0x0E0067, 0x0E0062, 0x0E0077, 0x0E006C, 0x0E0073, 0x0E007F, 0,
+    0  // null-terminating the list
+};
+
+const uc32 UnicodePropertySequences::kEmojiZWJSequences[] = {
+    0x01F468, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F468, 0,
+    0x01F441, 0x00FE0F, 0x00200D, 0x01F5E8, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F468, 0,
+    0x01F469, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F469, 0,
+    0x01F469, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F48B, 0x00200D,
+        0x01F468, 0,
+    0x01F469, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F48B, 0x00200D,
+        0x01F469, 0,
+    0x01F469, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F467, 0,
+    0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FF, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FF, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FB, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FF, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FB, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FC, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FF, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FB, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FC, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FD, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FB, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FC, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FD, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FE, 0,
+    0x01F9D1, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0,
+    0x01F9D1, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FC, 0,
+    0x01F9D1, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FC, 0,
+    0x01F9D1, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FD, 0,
+    0x01F9D1, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FC, 0,
+    0x01F9D1, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FD, 0,
+    0x01F9D1, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FE, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FC, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FD, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FE, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FF, 0,
+    0x01F468, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F9BD, 0,
+    0x01F469, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F469, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F469, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F469, 0x00200D, 0x01F33E, 0,
+    0x01F469, 0x00200D, 0x01F373, 0,
+    0x01F469, 0x00200D, 0x01F393, 0,
+    0x01F469, 0x00200D, 0x01F3A4, 0,
+    0x01F469, 0x00200D, 0x01F3A8, 0,
+    0x01F469, 0x00200D, 0x01F3EB, 0,
+    0x01F469, 0x00200D, 0x01F3ED, 0,
+    0x01F469, 0x00200D, 0x01F4BB, 0,
+    0x01F469, 0x00200D, 0x01F4BC, 0,
+    0x01F469, 0x00200D, 0x01F527, 0,
+    0x01F469, 0x00200D, 0x01F52C, 0,
+    0x01F469, 0x00200D, 0x01F680, 0,
+    0x01F469, 0x00200D, 0x01F692, 0,
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+    0x01F469, 0x01F3FE, 0x00200D, 0x01F9B2, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F9B3, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F9B0, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F9B1, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F9B2, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F9B3, 0,
+    0x01F3F3, 0x00FE0F, 0x00200D, 0x01F308, 0,
+    0x01F3F4, 0x00200D, 0x002620, 0x00FE0F, 0,
+    0x01F415, 0x00200D, 0x01F9BA, 0,
+    0x01F482, 0x01F3FB, 0x00200D, 0x002640, 0x00FE0F, 0,
+    0  // null-terminating the list
+};
+// clang-format on
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTL_SUPPORT
diff --git a/js/src/regexp/property-sequences.h b/js/src/regexp/property-sequences.h
new file mode 100644
index 0000000000..cbf2ea1fc0
--- /dev/null
+++ b/js/src/regexp/property-sequences.h
@@ -0,0 +1,26 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_PROPERTY_SEQUENCES_H_
+#define V8_REGEXP_PROPERTY_SEQUENCES_H_
+
+#ifdef V8_INTL_SUPPORT
+
+
+namespace v8 {
+namespace internal {
+
+class UnicodePropertySequences : public AllStatic {
+ public:
+  static const uc32 kEmojiFlagSequences[];
+  static const uc32 kEmojiTagSequences[];
+  static const uc32 kEmojiZWJSequences[];
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTL_SUPPORT
+
+#endif  // V8_REGEXP_PROPERTY_SEQUENCES_H_
diff --git a/js/src/regexp/regexp-ast.cc b/js/src/regexp/regexp-ast.cc
new file mode 100644
index 0000000000..8f7dd69478
--- /dev/null
+++ b/js/src/regexp/regexp-ast.cc
@@ -0,0 +1,342 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-ast.h"
+
+namespace v8 {
+namespace internal {
+
+#define MAKE_ACCEPT(Name)                                          \
+  void* RegExp##Name::Accept(RegExpVisitor* visitor, void* data) { \
+    return visitor->Visit##Name(this, data);                       \
+  }
+FOR_EACH_REG_EXP_TREE_TYPE(MAKE_ACCEPT)
+#undef MAKE_ACCEPT
+
+#define MAKE_TYPE_CASE(Name)                               \
+  RegExp##Name* RegExpTree::As##Name() { return nullptr; } \
+  bool RegExpTree::Is##Name() { return false; }
+FOR_EACH_REG_EXP_TREE_TYPE(MAKE_TYPE_CASE)
+#undef MAKE_TYPE_CASE
+
+#define MAKE_TYPE_CASE(Name)                              \
+  RegExp##Name* RegExp##Name::As##Name() { return this; } \
+  bool RegExp##Name::Is##Name() { return true; }
+FOR_EACH_REG_EXP_TREE_TYPE(MAKE_TYPE_CASE)
+#undef MAKE_TYPE_CASE
+
+
+static Interval ListCaptureRegisters(ZoneList<RegExpTree*>* children) {
+  Interval result = Interval::Empty();
+  for (int i = 0; i < children->length(); i++)
+    result = result.Union(children->at(i)->CaptureRegisters());
+  return result;
+}
+
+
+Interval RegExpAlternative::CaptureRegisters() {
+  return ListCaptureRegisters(nodes());
+}
+
+
+Interval RegExpDisjunction::CaptureRegisters() {
+  return ListCaptureRegisters(alternatives());
+}
+
+
+Interval RegExpLookaround::CaptureRegisters() {
+  return body()->CaptureRegisters();
+}
+
+
+Interval RegExpCapture::CaptureRegisters() {
+  Interval self(StartRegister(index()), EndRegister(index()));
+  return self.Union(body()->CaptureRegisters());
+}
+
+
+Interval RegExpQuantifier::CaptureRegisters() {
+  return body()->CaptureRegisters();
+}
+
+
+bool RegExpAssertion::IsAnchoredAtStart() {
+  return assertion_type() == RegExpAssertion::START_OF_INPUT;
+}
+
+
+bool RegExpAssertion::IsAnchoredAtEnd() {
+  return assertion_type() == RegExpAssertion::END_OF_INPUT;
+}
+
+
+bool RegExpAlternative::IsAnchoredAtStart() {
+  ZoneList<RegExpTree*>* nodes = this->nodes();
+  for (int i = 0; i < nodes->length(); i++) {
+    RegExpTree* node = nodes->at(i);
+    if (node->IsAnchoredAtStart()) {
+      return true;
+    }
+    if (node->max_match() > 0) {
+      return false;
+    }
+  }
+  return false;
+}
+
+
+bool RegExpAlternative::IsAnchoredAtEnd() {
+  ZoneList<RegExpTree*>* nodes = this->nodes();
+  for (int i = nodes->length() - 1; i >= 0; i--) {
+    RegExpTree* node = nodes->at(i);
+    if (node->IsAnchoredAtEnd()) {
+      return true;
+    }
+    if (node->max_match() > 0) {
+      return false;
+    }
+  }
+  return false;
+}
+
+
+bool RegExpDisjunction::IsAnchoredAtStart() {
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  for (int i = 0; i < alternatives->length(); i++) {
+    if (!alternatives->at(i)->IsAnchoredAtStart()) return false;
+  }
+  return true;
+}
+
+
+bool RegExpDisjunction::IsAnchoredAtEnd() {
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  for (int i = 0; i < alternatives->length(); i++) {
+    if (!alternatives->at(i)->IsAnchoredAtEnd()) return false;
+  }
+  return true;
+}
+
+
+bool RegExpLookaround::IsAnchoredAtStart() {
+  return is_positive() && type() == LOOKAHEAD && body()->IsAnchoredAtStart();
+}
+
+
+bool RegExpCapture::IsAnchoredAtStart() { return body()->IsAnchoredAtStart(); }
+
+
+bool RegExpCapture::IsAnchoredAtEnd() { return body()->IsAnchoredAtEnd(); }
+
+
+// Convert regular expression trees to a simple sexp representation.
+// This representation should be different from the input grammar
+// in as many cases as possible, to make it more difficult for incorrect
+// parses to look as correct ones which is likely if the input and
+// output formats are alike.
+class RegExpUnparser final : public RegExpVisitor {
+ public:
+  RegExpUnparser(std::ostream& os, Zone* zone) : os_(os), zone_(zone) {}
+  void VisitCharacterRange(CharacterRange that);
+#define MAKE_CASE(Name) void* Visit##Name(RegExp##Name*, void* data) override;
+  FOR_EACH_REG_EXP_TREE_TYPE(MAKE_CASE)
+#undef MAKE_CASE
+ private:
+  std::ostream& os_;
+  Zone* zone_;
+};
+
+
+void* RegExpUnparser::VisitDisjunction(RegExpDisjunction* that, void* data) {
+  os_ << "(|";
+  for (int i = 0; i < that->alternatives()->length(); i++) {
+    os_ << " ";
+    that->alternatives()->at(i)->Accept(this, data);
+  }
+  os_ << ")";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitAlternative(RegExpAlternative* that, void* data) {
+  os_ << "(:";
+  for (int i = 0; i < that->nodes()->length(); i++) {
+    os_ << " ";
+    that->nodes()->at(i)->Accept(this, data);
+  }
+  os_ << ")";
+  return nullptr;
+}
+
+
+void RegExpUnparser::VisitCharacterRange(CharacterRange that) {
+  os_ << AsUC32(that.from());
+  if (!that.IsSingleton()) {
+    os_ << "-" << AsUC32(that.to());
+  }
+}
+
+
+void* RegExpUnparser::VisitCharacterClass(RegExpCharacterClass* that,
+                                          void* data) {
+  if (that->is_negated()) os_ << "^";
+  os_ << "[";
+  for (int i = 0; i < that->ranges(zone_)->length(); i++) {
+    if (i > 0) os_ << " ";
+    VisitCharacterRange(that->ranges(zone_)->at(i));
+  }
+  os_ << "]";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitAssertion(RegExpAssertion* that, void* data) {
+  switch (that->assertion_type()) {
+    case RegExpAssertion::START_OF_INPUT:
+      os_ << "@^i";
+      break;
+    case RegExpAssertion::END_OF_INPUT:
+      os_ << "@$i";
+      break;
+    case RegExpAssertion::START_OF_LINE:
+      os_ << "@^l";
+      break;
+    case RegExpAssertion::END_OF_LINE:
+      os_ << "@$l";
+      break;
+    case RegExpAssertion::BOUNDARY:
+      os_ << "@b";
+      break;
+    case RegExpAssertion::NON_BOUNDARY:
+      os_ << "@B";
+      break;
+  }
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitAtom(RegExpAtom* that, void* data) {
+  os_ << "'";
+  Vector<const uc16> chardata = that->data();
+  for (int i = 0; i < chardata.length(); i++) {
+    os_ << AsUC16(chardata[i]);
+  }
+  os_ << "'";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitText(RegExpText* that, void* data) {
+  if (that->elements()->length() == 1) {
+    that->elements()->at(0).tree()->Accept(this, data);
+  } else {
+    os_ << "(!";
+    for (int i = 0; i < that->elements()->length(); i++) {
+      os_ << " ";
+      that->elements()->at(i).tree()->Accept(this, data);
+    }
+    os_ << ")";
+  }
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitQuantifier(RegExpQuantifier* that, void* data) {
+  os_ << "(# " << that->min() << " ";
+  if (that->max() == RegExpTree::kInfinity) {
+    os_ << "- ";
+  } else {
+    os_ << that->max() << " ";
+  }
+  os_ << (that->is_greedy() ? "g " : that->is_possessive() ? "p " : "n ");
+  that->body()->Accept(this, data);
+  os_ << ")";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitCapture(RegExpCapture* that, void* data) {
+  os_ << "(^ ";
+  that->body()->Accept(this, data);
+  os_ << ")";
+  return nullptr;
+}
+
+void* RegExpUnparser::VisitGroup(RegExpGroup* that, void* data) {
+  os_ << "(?: ";
+  that->body()->Accept(this, data);
+  os_ << ")";
+  return nullptr;
+}
+
+void* RegExpUnparser::VisitLookaround(RegExpLookaround* that, void* data) {
+  os_ << "(";
+  os_ << (that->type() == RegExpLookaround::LOOKAHEAD ? "->" : "<-");
+  os_ << (that->is_positive() ? " + " : " - ");
+  that->body()->Accept(this, data);
+  os_ << ")";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitBackReference(RegExpBackReference* that,
+                                         void* data) {
+  os_ << "(<- " << that->index() << ")";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitEmpty(RegExpEmpty* that, void* data) {
+  os_ << '%';
+  return nullptr;
+}
+
+
+std::ostream& RegExpTree::Print(std::ostream& os, Zone* zone) {  // NOLINT
+  RegExpUnparser unparser(os, zone);
+  Accept(&unparser, nullptr);
+  return os;
+}
+
+
+RegExpDisjunction::RegExpDisjunction(ZoneList<RegExpTree*>* alternatives)
+    : alternatives_(alternatives) {
+  DCHECK_LT(1, alternatives->length());
+  RegExpTree* first_alternative = alternatives->at(0);
+  min_match_ = first_alternative->min_match();
+  max_match_ = first_alternative->max_match();
+  for (int i = 1; i < alternatives->length(); i++) {
+    RegExpTree* alternative = alternatives->at(i);
+    min_match_ = Min(min_match_, alternative->min_match());
+    max_match_ = Max(max_match_, alternative->max_match());
+  }
+}
+
+
+static int IncreaseBy(int previous, int increase) {
+  if (RegExpTree::kInfinity - previous < increase) {
+    return RegExpTree::kInfinity;
+  } else {
+    return previous + increase;
+  }
+}
+
+
+RegExpAlternative::RegExpAlternative(ZoneList<RegExpTree*>* nodes)
+    : nodes_(nodes) {
+  DCHECK_LT(1, nodes->length());
+  min_match_ = 0;
+  max_match_ = 0;
+  for (int i = 0; i < nodes->length(); i++) {
+    RegExpTree* node = nodes->at(i);
+    int node_min_match = node->min_match();
+    min_match_ = IncreaseBy(min_match_, node_min_match);
+    int node_max_match = node->max_match();
+    max_match_ = IncreaseBy(max_match_, node_max_match);
+  }
+}
+
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-ast.h b/js/src/regexp/regexp-ast.h
new file mode 100644
index 0000000000..540fdce80a
--- /dev/null
+++ b/js/src/regexp/regexp-ast.h
@@ -0,0 +1,599 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_AST_H_
+#define V8_REGEXP_REGEXP_AST_H_
+
+
+namespace v8 {
+namespace internal {
+
+#define FOR_EACH_REG_EXP_TREE_TYPE(VISIT) \
+  VISIT(Disjunction)                      \
+  VISIT(Alternative)                      \
+  VISIT(Assertion)                        \
+  VISIT(CharacterClass)                   \
+  VISIT(Atom)                             \
+  VISIT(Quantifier)                       \
+  VISIT(Capture)                          \
+  VISIT(Group)                            \
+  VISIT(Lookaround)                       \
+  VISIT(BackReference)                    \
+  VISIT(Empty)                            \
+  VISIT(Text)
+
+#define FORWARD_DECLARE(Name) class RegExp##Name;
+FOR_EACH_REG_EXP_TREE_TYPE(FORWARD_DECLARE)
+#undef FORWARD_DECLARE
+
+class RegExpCompiler;
+class RegExpNode;
+class RegExpTree;
+
+class RegExpVisitor {
+ public:
+  virtual ~RegExpVisitor() = default;
+#define MAKE_CASE(Name) \
+  virtual void* Visit##Name(RegExp##Name*, void* data) = 0;
+  FOR_EACH_REG_EXP_TREE_TYPE(MAKE_CASE)
+#undef MAKE_CASE
+};
+
+
+// A simple closed interval.
+class Interval {
+ public:
+  Interval() : from_(kNone), to_(kNone - 1) {}  // '- 1' for branchless size().
+  Interval(int from, int to) : from_(from), to_(to) {}
+  Interval Union(Interval that) {
+    if (that.from_ == kNone)
+      return *this;
+    else if (from_ == kNone)
+      return that;
+    else
+      return Interval(Min(from_, that.from_), Max(to_, that.to_));
+  }
+
+  bool Contains(int value) { return (from_ <= value) && (value <= to_); }
+  bool is_empty() { return from_ == kNone; }
+  int from() const { return from_; }
+  int to() const { return to_; }
+  int size() const { return to_ - from_ + 1; }
+
+  static Interval Empty() { return Interval(); }
+
+  static constexpr int kNone = -1;
+
+ private:
+  int from_;
+  int to_;
+};
+
+
+// Represents code units in the range from from_ to to_, both ends are
+// inclusive.
+class CharacterRange {
+ public:
+  CharacterRange() : from_(0), to_(0) {}
+  // For compatibility with the CHECK_OK macro
+  CharacterRange(void* null) { DCHECK_NULL(null); }  // NOLINT
+  V8_EXPORT_PRIVATE static void AddClassEscape(char type,
+                                               ZoneList<CharacterRange>* ranges,
+                                               Zone* zone);
+  // Add class escapes. Add case equivalent closure for \w and \W if necessary.
+  V8_EXPORT_PRIVATE static void AddClassEscape(
+      char type, ZoneList<CharacterRange>* ranges,
+      bool add_unicode_case_equivalents, Zone* zone);
+  static Vector<const int> GetWordBounds();
+  static inline CharacterRange Singleton(uc32 value) {
+    return CharacterRange(value, value);
+  }
+  static inline CharacterRange Range(uc32 from, uc32 to) {
+    DCHECK(0 <= from && to <= String::kMaxCodePoint);
+    DCHECK(static_cast<uint32_t>(from) <= static_cast<uint32_t>(to));
+    return CharacterRange(from, to);
+  }
+  static inline CharacterRange Everything() {
+    return CharacterRange(0, String::kMaxCodePoint);
+  }
+  static inline ZoneList<CharacterRange>* List(Zone* zone,
+                                               CharacterRange range) {
+    ZoneList<CharacterRange>* list =
+        new (zone) ZoneList<CharacterRange>(1, zone);
+    list->Add(range, zone);
+    return list;
+  }
+  bool Contains(uc32 i) { return from_ <= i && i <= to_; }
+  uc32 from() const { return from_; }
+  void set_from(uc32 value) { from_ = value; }
+  uc32 to() const { return to_; }
+  void set_to(uc32 value) { to_ = value; }
+  bool is_valid() { return from_ <= to_; }
+  bool IsEverything(uc32 max) { return from_ == 0 && to_ >= max; }
+  bool IsSingleton() { return (from_ == to_); }
+  V8_EXPORT_PRIVATE static void AddCaseEquivalents(
+      Isolate* isolate, Zone* zone, ZoneList<CharacterRange>* ranges,
+      bool is_one_byte);
+  // Whether a range list is in canonical form: Ranges ordered by from value,
+  // and ranges non-overlapping and non-adjacent.
+  V8_EXPORT_PRIVATE static bool IsCanonical(ZoneList<CharacterRange>* ranges);
+  // Convert range list to canonical form. The characters covered by the ranges
+  // will still be the same, but no character is in more than one range, and
+  // adjacent ranges are merged. The resulting list may be shorter than the
+  // original, but cannot be longer.
+  static void Canonicalize(ZoneList<CharacterRange>* ranges);
+  // Negate the contents of a character range in canonical form.
+  static void Negate(ZoneList<CharacterRange>* src,
+                     ZoneList<CharacterRange>* dst, Zone* zone);
+  static const int kStartMarker = (1 << 24);
+  static const int kPayloadMask = (1 << 24) - 1;
+
+ private:
+  CharacterRange(uc32 from, uc32 to) : from_(from), to_(to) {}
+
+  uc32 from_;
+  uc32 to_;
+};
+
+class CharacterSet final {
+ public:
+  explicit CharacterSet(uc16 standard_set_type)
+      : ranges_(nullptr), standard_set_type_(standard_set_type) {}
+  explicit CharacterSet(ZoneList<CharacterRange>* ranges)
+      : ranges_(ranges), standard_set_type_(0) {}
+  ZoneList<CharacterRange>* ranges(Zone* zone);
+  uc16 standard_set_type() const { return standard_set_type_; }
+  void set_standard_set_type(uc16 special_set_type) {
+    standard_set_type_ = special_set_type;
+  }
+  bool is_standard() { return standard_set_type_ != 0; }
+  V8_EXPORT_PRIVATE void Canonicalize();
+
+ private:
+  ZoneList<CharacterRange>* ranges_;
+  // If non-zero, the value represents a standard set (e.g., all whitespace
+  // characters) without having to expand the ranges.
+  uc16 standard_set_type_;
+};
+
+class TextElement final {
+ public:
+  enum TextType { ATOM, CHAR_CLASS };
+
+  static TextElement Atom(RegExpAtom* atom);
+  static TextElement CharClass(RegExpCharacterClass* char_class);
+
+  int cp_offset() const { return cp_offset_; }
+  void set_cp_offset(int cp_offset) { cp_offset_ = cp_offset; }
+  int length() const;
+
+  TextType text_type() const { return text_type_; }
+
+  RegExpTree* tree() const { return tree_; }
+
+  RegExpAtom* atom() const {
+    DCHECK(text_type() == ATOM);
+    return reinterpret_cast<RegExpAtom*>(tree());
+  }
+
+  RegExpCharacterClass* char_class() const {
+    DCHECK(text_type() == CHAR_CLASS);
+    return reinterpret_cast<RegExpCharacterClass*>(tree());
+  }
+
+ private:
+  TextElement(TextType text_type, RegExpTree* tree)
+      : cp_offset_(-1), text_type_(text_type), tree_(tree) {}
+
+  int cp_offset_;
+  TextType text_type_;
+  RegExpTree* tree_;
+};
+
+
+class RegExpTree : public ZoneObject {
+ public:
+  static const int kInfinity = kMaxInt;
+  virtual ~RegExpTree() = default;
+  virtual void* Accept(RegExpVisitor* visitor, void* data) = 0;
+  virtual RegExpNode* ToNode(RegExpCompiler* compiler,
+                             RegExpNode* on_success) = 0;
+  virtual bool IsTextElement() { return false; }
+  virtual bool IsAnchoredAtStart() { return false; }
+  virtual bool IsAnchoredAtEnd() { return false; }
+  virtual int min_match() = 0;
+  virtual int max_match() = 0;
+  // Returns the interval of registers used for captures within this
+  // expression.
+  virtual Interval CaptureRegisters() { return Interval::Empty(); }
+  virtual void AppendToText(RegExpText* text, Zone* zone);
+  V8_EXPORT_PRIVATE std::ostream& Print(std::ostream& os,
+                                        Zone* zone);  // NOLINT
+#define MAKE_ASTYPE(Name)           \
+  virtual RegExp##Name* As##Name(); \
+  virtual bool Is##Name();
+  FOR_EACH_REG_EXP_TREE_TYPE(MAKE_ASTYPE)
+#undef MAKE_ASTYPE
+};
+
+
+class RegExpDisjunction final : public RegExpTree {
+ public:
+  explicit RegExpDisjunction(ZoneList<RegExpTree*>* alternatives);
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpDisjunction* AsDisjunction() override;
+  Interval CaptureRegisters() override;
+  bool IsDisjunction() override;
+  bool IsAnchoredAtStart() override;
+  bool IsAnchoredAtEnd() override;
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+  ZoneList<RegExpTree*>* alternatives() { return alternatives_; }
+
+ private:
+  bool SortConsecutiveAtoms(RegExpCompiler* compiler);
+  void RationalizeConsecutiveAtoms(RegExpCompiler* compiler);
+  void FixSingleCharacterDisjunctions(RegExpCompiler* compiler);
+  ZoneList<RegExpTree*>* alternatives_;
+  int min_match_;
+  int max_match_;
+};
+
+
+class RegExpAlternative final : public RegExpTree {
+ public:
+  explicit RegExpAlternative(ZoneList<RegExpTree*>* nodes);
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpAlternative* AsAlternative() override;
+  Interval CaptureRegisters() override;
+  bool IsAlternative() override;
+  bool IsAnchoredAtStart() override;
+  bool IsAnchoredAtEnd() override;
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+  ZoneList<RegExpTree*>* nodes() { return nodes_; }
+
+ private:
+  ZoneList<RegExpTree*>* nodes_;
+  int min_match_;
+  int max_match_;
+};
+
+
+class RegExpAssertion final : public RegExpTree {
+ public:
+  enum AssertionType {
+    START_OF_LINE = 0,
+    START_OF_INPUT = 1,
+    END_OF_LINE = 2,
+    END_OF_INPUT = 3,
+    BOUNDARY = 4,
+    NON_BOUNDARY = 5,
+    LAST_TYPE = NON_BOUNDARY,
+  };
+  RegExpAssertion(AssertionType type, JSRegExp::Flags flags)
+      : assertion_type_(type), flags_(flags) {}
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpAssertion* AsAssertion() override;
+  bool IsAssertion() override;
+  bool IsAnchoredAtStart() override;
+  bool IsAnchoredAtEnd() override;
+  int min_match() override { return 0; }
+  int max_match() override { return 0; }
+  AssertionType assertion_type() const { return assertion_type_; }
+  JSRegExp::Flags flags() const { return flags_; }
+
+ private:
+  const AssertionType assertion_type_;
+  const JSRegExp::Flags flags_;
+};
+
+
+class RegExpCharacterClass final : public RegExpTree {
+ public:
+  // NEGATED: The character class is negated and should match everything but
+  //     the specified ranges.
+  // CONTAINS_SPLIT_SURROGATE: The character class contains part of a split
+  //     surrogate and should not be unicode-desugared (crbug.com/641091).
+  enum Flag {
+    NEGATED = 1 << 0,
+    CONTAINS_SPLIT_SURROGATE = 1 << 1,
+  };
+  using CharacterClassFlags = base::Flags<Flag>;
+
+  RegExpCharacterClass(
+      Zone* zone, ZoneList<CharacterRange>* ranges, JSRegExp::Flags flags,
+      CharacterClassFlags character_class_flags = CharacterClassFlags())
+      : set_(ranges),
+        flags_(flags),
+        character_class_flags_(character_class_flags) {
+    // Convert the empty set of ranges to the negated Everything() range.
+    if (ranges->is_empty()) {
+      ranges->Add(CharacterRange::Everything(), zone);
+      character_class_flags_ ^= NEGATED;
+    }
+  }
+  RegExpCharacterClass(uc16 type, JSRegExp::Flags flags)
+      : set_(type),
+        flags_(flags),
+        character_class_flags_(CharacterClassFlags()) {}
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpCharacterClass* AsCharacterClass() override;
+  bool IsCharacterClass() override;
+  bool IsTextElement() override { return true; }
+  int min_match() override { return 1; }
+  // The character class may match two code units for unicode regexps.
+  // TODO(yangguo): we should split this class for usage in TextElement, and
+  //                make max_match() dependent on the character class content.
+  int max_match() override { return 2; }
+  void AppendToText(RegExpText* text, Zone* zone) override;
+  CharacterSet character_set() { return set_; }
+  // TODO(lrn): Remove need for complex version if is_standard that
+  // recognizes a mangled standard set and just do { return set_.is_special(); }
+  bool is_standard(Zone* zone);
+  // Returns a value representing the standard character set if is_standard()
+  // returns true.
+  // Currently used values are:
+  // s : unicode whitespace
+  // S : unicode non-whitespace
+  // w : ASCII word character (digit, letter, underscore)
+  // W : non-ASCII word character
+  // d : ASCII digit
+  // D : non-ASCII digit
+  // . : non-newline
+  // * : All characters, for advancing unanchored regexp
+  uc16 standard_type() const { return set_.standard_set_type(); }
+  ZoneList<CharacterRange>* ranges(Zone* zone) { return set_.ranges(zone); }
+  bool is_negated() const { return (character_class_flags_ & NEGATED) != 0; }
+  JSRegExp::Flags flags() const { return flags_; }
+  bool contains_split_surrogate() const {
+    return (character_class_flags_ & CONTAINS_SPLIT_SURROGATE) != 0;
+  }
+
+ private:
+  CharacterSet set_;
+  const JSRegExp::Flags flags_;
+  CharacterClassFlags character_class_flags_;
+};
+
+
+class RegExpAtom final : public RegExpTree {
+ public:
+  explicit RegExpAtom(Vector<const uc16> data, JSRegExp::Flags flags)
+      : data_(data), flags_(flags) {}
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpAtom* AsAtom() override;
+  bool IsAtom() override;
+  bool IsTextElement() override { return true; }
+  int min_match() override { return data_.length(); }
+  int max_match() override { return data_.length(); }
+  void AppendToText(RegExpText* text, Zone* zone) override;
+  Vector<const uc16> data() { return data_; }
+  int length() { return data_.length(); }
+  JSRegExp::Flags flags() const { return flags_; }
+  bool ignore_case() const { return (flags_ & JSRegExp::kIgnoreCase) != 0; }
+
+ private:
+  Vector<const uc16> data_;
+  const JSRegExp::Flags flags_;
+};
+
+
+class RegExpText final : public RegExpTree {
+ public:
+  explicit RegExpText(Zone* zone) : elements_(2, zone), length_(0) {}
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpText* AsText() override;
+  bool IsText() override;
+  bool IsTextElement() override { return true; }
+  int min_match() override { return length_; }
+  int max_match() override { return length_; }
+  void AppendToText(RegExpText* text, Zone* zone) override;
+  void AddElement(TextElement elm, Zone* zone) {
+    elements_.Add(elm, zone);
+    length_ += elm.length();
+  }
+  ZoneList<TextElement>* elements() { return &elements_; }
+
+ private:
+  ZoneList<TextElement> elements_;
+  int length_;
+};
+
+
+class RegExpQuantifier final : public RegExpTree {
+ public:
+  enum QuantifierType { GREEDY, NON_GREEDY, POSSESSIVE };
+  RegExpQuantifier(int min, int max, QuantifierType type, RegExpTree* body)
+      : body_(body),
+        min_(min),
+        max_(max),
+        quantifier_type_(type) {
+    if (min > 0 && body->min_match() > kInfinity / min) {
+      min_match_ = kInfinity;
+    } else {
+      min_match_ = min * body->min_match();
+    }
+    if (max > 0 && body->max_match() > kInfinity / max) {
+      max_match_ = kInfinity;
+    } else {
+      max_match_ = max * body->max_match();
+    }
+  }
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  static RegExpNode* ToNode(int min, int max, bool is_greedy, RegExpTree* body,
+                            RegExpCompiler* compiler, RegExpNode* on_success,
+                            bool not_at_start = false);
+  RegExpQuantifier* AsQuantifier() override;
+  Interval CaptureRegisters() override;
+  bool IsQuantifier() override;
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+  int min() { return min_; }
+  int max() { return max_; }
+  bool is_possessive() { return quantifier_type_ == POSSESSIVE; }
+  bool is_non_greedy() { return quantifier_type_ == NON_GREEDY; }
+  bool is_greedy() { return quantifier_type_ == GREEDY; }
+  RegExpTree* body() { return body_; }
+
+ private:
+  RegExpTree* body_;
+  int min_;
+  int max_;
+  int min_match_;
+  int max_match_;
+  QuantifierType quantifier_type_;
+};
+
+
+class RegExpCapture final : public RegExpTree {
+ public:
+  explicit RegExpCapture(int index)
+      : body_(nullptr), index_(index), name_(nullptr) {}
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  static RegExpNode* ToNode(RegExpTree* body, int index,
+                            RegExpCompiler* compiler, RegExpNode* on_success);
+  RegExpCapture* AsCapture() override;
+  bool IsAnchoredAtStart() override;
+  bool IsAnchoredAtEnd() override;
+  Interval CaptureRegisters() override;
+  bool IsCapture() override;
+  int min_match() override { return body_->min_match(); }
+  int max_match() override { return body_->max_match(); }
+  RegExpTree* body() { return body_; }
+  void set_body(RegExpTree* body) { body_ = body; }
+  int index() const { return index_; }
+  const ZoneVector<uc16>* name() const { return name_; }
+  void set_name(const ZoneVector<uc16>* name) { name_ = name; }
+  static int StartRegister(int index) { return index * 2; }
+  static int EndRegister(int index) { return index * 2 + 1; }
+
+ private:
+  RegExpTree* body_;
+  int index_;
+  const ZoneVector<uc16>* name_;
+};
+
+class RegExpGroup final : public RegExpTree {
+ public:
+  explicit RegExpGroup(RegExpTree* body) : body_(body) {}
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler,
+                     RegExpNode* on_success) override {
+    return body_->ToNode(compiler, on_success);
+  }
+  RegExpGroup* AsGroup() override;
+  bool IsAnchoredAtStart() override { return body_->IsAnchoredAtStart(); }
+  bool IsAnchoredAtEnd() override { return body_->IsAnchoredAtEnd(); }
+  bool IsGroup() override;
+  int min_match() override { return body_->min_match(); }
+  int max_match() override { return body_->max_match(); }
+  Interval CaptureRegisters() override { return body_->CaptureRegisters(); }
+  RegExpTree* body() { return body_; }
+
+ private:
+  RegExpTree* body_;
+};
+
+class RegExpLookaround final : public RegExpTree {
+ public:
+  enum Type { LOOKAHEAD, LOOKBEHIND };
+
+  RegExpLookaround(RegExpTree* body, bool is_positive, int capture_count,
+                   int capture_from, Type type)
+      : body_(body),
+        is_positive_(is_positive),
+        capture_count_(capture_count),
+        capture_from_(capture_from),
+        type_(type) {}
+
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpLookaround* AsLookaround() override;
+  Interval CaptureRegisters() override;
+  bool IsLookaround() override;
+  bool IsAnchoredAtStart() override;
+  int min_match() override { return 0; }
+  int max_match() override { return 0; }
+  RegExpTree* body() { return body_; }
+  bool is_positive() { return is_positive_; }
+  int capture_count() { return capture_count_; }
+  int capture_from() { return capture_from_; }
+  Type type() { return type_; }
+
+  class Builder {
+   public:
+    Builder(bool is_positive, RegExpNode* on_success,
+            int stack_pointer_register, int position_register,
+            int capture_register_count = 0, int capture_register_start = 0);
+    RegExpNode* on_match_success() { return on_match_success_; }
+    RegExpNode* ForMatch(RegExpNode* match);
+
+   private:
+    bool is_positive_;
+    RegExpNode* on_match_success_;
+    RegExpNode* on_success_;
+    int stack_pointer_register_;
+    int position_register_;
+  };
+
+ private:
+  RegExpTree* body_;
+  bool is_positive_;
+  int capture_count_;
+  int capture_from_;
+  Type type_;
+};
+
+
+class RegExpBackReference final : public RegExpTree {
+ public:
+  explicit RegExpBackReference(JSRegExp::Flags flags)
+      : capture_(nullptr), name_(nullptr), flags_(flags) {}
+  RegExpBackReference(RegExpCapture* capture, JSRegExp::Flags flags)
+      : capture_(capture), name_(nullptr), flags_(flags) {}
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpBackReference* AsBackReference() override;
+  bool IsBackReference() override;
+  int min_match() override { return 0; }
+  // The back reference may be recursive, e.g. /(\2)(\1)/. To avoid infinite
+  // recursion, we give up. Ignorance is bliss.
+  int max_match() override { return kInfinity; }
+  int index() { return capture_->index(); }
+  RegExpCapture* capture() { return capture_; }
+  void set_capture(RegExpCapture* capture) { capture_ = capture; }
+  const ZoneVector<uc16>* name() const { return name_; }
+  void set_name(const ZoneVector<uc16>* name) { name_ = name; }
+
+ private:
+  RegExpCapture* capture_;
+  const ZoneVector<uc16>* name_;
+  const JSRegExp::Flags flags_;
+};
+
+
+class RegExpEmpty final : public RegExpTree {
+ public:
+  RegExpEmpty() = default;
+  void* Accept(RegExpVisitor* visitor, void* data) override;
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
+  RegExpEmpty* AsEmpty() override;
+  bool IsEmpty() override;
+  int min_match() override { return 0; }
+  int max_match() override { return 0; }
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_AST_H_
diff --git a/js/src/regexp/regexp-bytecode-generator-inl.h b/js/src/regexp/regexp-bytecode-generator-inl.h
new file mode 100644
index 0000000000..69a054fd20
--- /dev/null
+++ b/js/src/regexp/regexp-bytecode-generator-inl.h
@@ -0,0 +1,55 @@
+// Copyright 2008-2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_BYTECODE_GENERATOR_INL_H_
+#define V8_REGEXP_REGEXP_BYTECODE_GENERATOR_INL_H_
+
+#include "regexp/regexp-bytecode-generator.h"
+
+#include "regexp/regexp-bytecodes.h"
+
+namespace v8 {
+namespace internal {
+
+void RegExpBytecodeGenerator::Emit(uint32_t byte, uint32_t twenty_four_bits) {
+  uint32_t word = ((twenty_four_bits << BYTECODE_SHIFT) | byte);
+  DCHECK(pc_ <= buffer_.length());
+  if (pc_ + 3 >= buffer_.length()) {
+    Expand();
+  }
+  *reinterpret_cast<uint32_t*>(buffer_.begin() + pc_) = word;
+  pc_ += 4;
+}
+
+void RegExpBytecodeGenerator::Emit16(uint32_t word) {
+  DCHECK(pc_ <= buffer_.length());
+  if (pc_ + 1 >= buffer_.length()) {
+    Expand();
+  }
+  *reinterpret_cast<uint16_t*>(buffer_.begin() + pc_) = word;
+  pc_ += 2;
+}
+
+void RegExpBytecodeGenerator::Emit8(uint32_t word) {
+  DCHECK(pc_ <= buffer_.length());
+  if (pc_ == buffer_.length()) {
+    Expand();
+  }
+  *reinterpret_cast<unsigned char*>(buffer_.begin() + pc_) = word;
+  pc_ += 1;
+}
+
+void RegExpBytecodeGenerator::Emit32(uint32_t word) {
+  DCHECK(pc_ <= buffer_.length());
+  if (pc_ + 3 >= buffer_.length()) {
+    Expand();
+  }
+  *reinterpret_cast<uint32_t*>(buffer_.begin() + pc_) = word;
+  pc_ += 4;
+}
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_BYTECODE_GENERATOR_INL_H_
diff --git a/js/src/regexp/regexp-bytecode-generator.cc b/js/src/regexp/regexp-bytecode-generator.cc
new file mode 100644
index 0000000000..239b27605f
--- /dev/null
+++ b/js/src/regexp/regexp-bytecode-generator.cc
@@ -0,0 +1,397 @@
+// Copyright 2008-2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-bytecode-generator.h"
+
+#include "regexp/regexp-bytecode-generator-inl.h"
+#include "regexp/regexp-bytecode-peephole.h"
+#include "regexp/regexp-bytecodes.h"
+#include "regexp/regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+RegExpBytecodeGenerator::RegExpBytecodeGenerator(Isolate* isolate, Zone* zone)
+    : RegExpMacroAssembler(isolate, zone),
+      buffer_(Vector<byte>::New(1024)),
+      pc_(0),
+      advance_current_end_(kInvalidPC),
+      jump_edges_(zone),
+      isolate_(isolate) {}
+
+RegExpBytecodeGenerator::~RegExpBytecodeGenerator() {
+  if (backtrack_.is_linked()) backtrack_.Unuse();
+  buffer_.Dispose();
+}
+
+RegExpBytecodeGenerator::IrregexpImplementation
+RegExpBytecodeGenerator::Implementation() {
+  return kBytecodeImplementation;
+}
+
+void RegExpBytecodeGenerator::Bind(Label* l) {
+  advance_current_end_ = kInvalidPC;
+  DCHECK(!l->is_bound());
+  if (l->is_linked()) {
+    int pos = l->pos();
+    while (pos != 0) {
+      int fixup = pos;
+      pos = *reinterpret_cast<int32_t*>(buffer_.begin() + fixup);
+      *reinterpret_cast<uint32_t*>(buffer_.begin() + fixup) = pc_;
+      jump_edges_.emplace(fixup, pc_);
+    }
+  }
+  l->bind_to(pc_);
+}
+
+void RegExpBytecodeGenerator::EmitOrLink(Label* l) {
+  if (l == nullptr) l = &backtrack_;
+  int pos = 0;
+  if (l->is_bound()) {
+    pos = l->pos();
+    jump_edges_.emplace(pc_, pos);
+  } else {
+    if (l->is_linked()) {
+      pos = l->pos();
+    }
+    l->link_to(pc_);
+  }
+  Emit32(pos);
+}
+
+void RegExpBytecodeGenerator::PopRegister(int register_index) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_POP_REGISTER, register_index);
+}
+
+void RegExpBytecodeGenerator::PushRegister(int register_index,
+                                           StackCheckFlag check_stack_limit) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_PUSH_REGISTER, register_index);
+}
+
+void RegExpBytecodeGenerator::WriteCurrentPositionToRegister(int register_index,
+                                                             int cp_offset) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_REGISTER_TO_CP, register_index);
+  Emit32(cp_offset);  // Current position offset.
+}
+
+void RegExpBytecodeGenerator::ClearRegisters(int reg_from, int reg_to) {
+  DCHECK(reg_from <= reg_to);
+  for (int reg = reg_from; reg <= reg_to; reg++) {
+    SetRegister(reg, -1);
+  }
+}
+
+void RegExpBytecodeGenerator::ReadCurrentPositionFromRegister(
+    int register_index) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_CP_TO_REGISTER, register_index);
+}
+
+void RegExpBytecodeGenerator::WriteStackPointerToRegister(int register_index) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_REGISTER_TO_SP, register_index);
+}
+
+void RegExpBytecodeGenerator::ReadStackPointerFromRegister(int register_index) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_SP_TO_REGISTER, register_index);
+}
+
+void RegExpBytecodeGenerator::SetCurrentPositionFromEnd(int by) {
+  DCHECK(is_uint24(by));
+  Emit(BC_SET_CURRENT_POSITION_FROM_END, by);
+}
+
+void RegExpBytecodeGenerator::SetRegister(int register_index, int to) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_REGISTER, register_index);
+  Emit32(to);
+}
+
+void RegExpBytecodeGenerator::AdvanceRegister(int register_index, int by) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_ADVANCE_REGISTER, register_index);
+  Emit32(by);
+}
+
+void RegExpBytecodeGenerator::PopCurrentPosition() { Emit(BC_POP_CP, 0); }
+
+void RegExpBytecodeGenerator::PushCurrentPosition() { Emit(BC_PUSH_CP, 0); }
+
+void RegExpBytecodeGenerator::Backtrack() { Emit(BC_POP_BT, 0); }
+
+void RegExpBytecodeGenerator::GoTo(Label* l) {
+  if (advance_current_end_ == pc_) {
+    // Combine advance current and goto.
+    pc_ = advance_current_start_;
+    Emit(BC_ADVANCE_CP_AND_GOTO, advance_current_offset_);
+    EmitOrLink(l);
+    advance_current_end_ = kInvalidPC;
+  } else {
+    // Regular goto.
+    Emit(BC_GOTO, 0);
+    EmitOrLink(l);
+  }
+}
+
+void RegExpBytecodeGenerator::PushBacktrack(Label* l) {
+  Emit(BC_PUSH_BT, 0);
+  EmitOrLink(l);
+}
+
+bool RegExpBytecodeGenerator::Succeed() {
+  Emit(BC_SUCCEED, 0);
+  return false;  // Restart matching for global regexp not supported.
+}
+
+void RegExpBytecodeGenerator::Fail() { Emit(BC_FAIL, 0); }
+
+void RegExpBytecodeGenerator::AdvanceCurrentPosition(int by) {
+  DCHECK_LE(kMinCPOffset, by);
+  DCHECK_GE(kMaxCPOffset, by);
+  advance_current_start_ = pc_;
+  advance_current_offset_ = by;
+  Emit(BC_ADVANCE_CP, by);
+  advance_current_end_ = pc_;
+}
+
+void RegExpBytecodeGenerator::CheckGreedyLoop(
+    Label* on_tos_equals_current_position) {
+  Emit(BC_CHECK_GREEDY, 0);
+  EmitOrLink(on_tos_equals_current_position);
+}
+
+void RegExpBytecodeGenerator::LoadCurrentCharacterImpl(int cp_offset,
+                                                       Label* on_failure,
+                                                       bool check_bounds,
+                                                       int characters,
+                                                       int eats_at_least) {
+  DCHECK_GE(eats_at_least, characters);
+  if (eats_at_least > characters && check_bounds) {
+    DCHECK(is_uint24(cp_offset + eats_at_least));
+    Emit(BC_CHECK_CURRENT_POSITION, cp_offset + eats_at_least);
+    EmitOrLink(on_failure);
+    check_bounds = false;  // Load below doesn't need to check.
+  }
+
+  DCHECK_LE(kMinCPOffset, cp_offset);
+  DCHECK_GE(kMaxCPOffset, cp_offset);
+  int bytecode;
+  if (check_bounds) {
+    if (characters == 4) {
+      bytecode = BC_LOAD_4_CURRENT_CHARS;
+    } else if (characters == 2) {
+      bytecode = BC_LOAD_2_CURRENT_CHARS;
+    } else {
+      DCHECK_EQ(1, characters);
+      bytecode = BC_LOAD_CURRENT_CHAR;
+    }
+  } else {
+    if (characters == 4) {
+      bytecode = BC_LOAD_4_CURRENT_CHARS_UNCHECKED;
+    } else if (characters == 2) {
+      bytecode = BC_LOAD_2_CURRENT_CHARS_UNCHECKED;
+    } else {
+      DCHECK_EQ(1, characters);
+      bytecode = BC_LOAD_CURRENT_CHAR_UNCHECKED;
+    }
+  }
+  Emit(bytecode, cp_offset);
+  if (check_bounds) EmitOrLink(on_failure);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterLT(uc16 limit, Label* on_less) {
+  Emit(BC_CHECK_LT, limit);
+  EmitOrLink(on_less);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterGT(uc16 limit, Label* on_greater) {
+  Emit(BC_CHECK_GT, limit);
+  EmitOrLink(on_greater);
+}
+
+void RegExpBytecodeGenerator::CheckCharacter(uint32_t c, Label* on_equal) {
+  if (c > MAX_FIRST_ARG) {
+    Emit(BC_CHECK_4_CHARS, 0);
+    Emit32(c);
+  } else {
+    Emit(BC_CHECK_CHAR, c);
+  }
+  EmitOrLink(on_equal);
+}
+
+void RegExpBytecodeGenerator::CheckAtStart(int cp_offset, Label* on_at_start) {
+  Emit(BC_CHECK_AT_START, cp_offset);
+  EmitOrLink(on_at_start);
+}
+
+void RegExpBytecodeGenerator::CheckNotAtStart(int cp_offset,
+                                              Label* on_not_at_start) {
+  Emit(BC_CHECK_NOT_AT_START, cp_offset);
+  EmitOrLink(on_not_at_start);
+}
+
+void RegExpBytecodeGenerator::CheckNotCharacter(uint32_t c,
+                                                Label* on_not_equal) {
+  if (c > MAX_FIRST_ARG) {
+    Emit(BC_CHECK_NOT_4_CHARS, 0);
+    Emit32(c);
+  } else {
+    Emit(BC_CHECK_NOT_CHAR, c);
+  }
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterAfterAnd(uint32_t c, uint32_t mask,
+                                                     Label* on_equal) {
+  if (c > MAX_FIRST_ARG) {
+    Emit(BC_AND_CHECK_4_CHARS, 0);
+    Emit32(c);
+  } else {
+    Emit(BC_AND_CHECK_CHAR, c);
+  }
+  Emit32(mask);
+  EmitOrLink(on_equal);
+}
+
+void RegExpBytecodeGenerator::CheckNotCharacterAfterAnd(uint32_t c,
+                                                        uint32_t mask,
+                                                        Label* on_not_equal) {
+  if (c > MAX_FIRST_ARG) {
+    Emit(BC_AND_CHECK_NOT_4_CHARS, 0);
+    Emit32(c);
+  } else {
+    Emit(BC_AND_CHECK_NOT_CHAR, c);
+  }
+  Emit32(mask);
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::CheckNotCharacterAfterMinusAnd(
+    uc16 c, uc16 minus, uc16 mask, Label* on_not_equal) {
+  Emit(BC_MINUS_AND_CHECK_NOT_CHAR, c);
+  Emit16(minus);
+  Emit16(mask);
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterInRange(uc16 from, uc16 to,
+                                                    Label* on_in_range) {
+  Emit(BC_CHECK_CHAR_IN_RANGE, 0);
+  Emit16(from);
+  Emit16(to);
+  EmitOrLink(on_in_range);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterNotInRange(uc16 from, uc16 to,
+                                                       Label* on_not_in_range) {
+  Emit(BC_CHECK_CHAR_NOT_IN_RANGE, 0);
+  Emit16(from);
+  Emit16(to);
+  EmitOrLink(on_not_in_range);
+}
+
+void RegExpBytecodeGenerator::CheckBitInTable(Handle<ByteArray> table,
+                                              Label* on_bit_set) {
+  Emit(BC_CHECK_BIT_IN_TABLE, 0);
+  EmitOrLink(on_bit_set);
+  for (int i = 0; i < kTableSize; i += kBitsPerByte) {
+    int byte = 0;
+    for (int j = 0; j < kBitsPerByte; j++) {
+      if (table->get(i + j) != 0) byte |= 1 << j;
+    }
+    Emit8(byte);
+  }
+}
+
+void RegExpBytecodeGenerator::CheckNotBackReference(int start_reg,
+                                                    bool read_backward,
+                                                    Label* on_not_equal) {
+  DCHECK_LE(0, start_reg);
+  DCHECK_GE(kMaxRegister, start_reg);
+  Emit(read_backward ? BC_CHECK_NOT_BACK_REF_BACKWARD : BC_CHECK_NOT_BACK_REF,
+       start_reg);
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::CheckNotBackReferenceIgnoreCase(
+    int start_reg, bool read_backward, bool unicode, Label* on_not_equal) {
+  DCHECK_LE(0, start_reg);
+  DCHECK_GE(kMaxRegister, start_reg);
+  Emit(read_backward ? (unicode ? BC_CHECK_NOT_BACK_REF_NO_CASE_UNICODE_BACKWARD
+                                : BC_CHECK_NOT_BACK_REF_NO_CASE_BACKWARD)
+                     : (unicode ? BC_CHECK_NOT_BACK_REF_NO_CASE_UNICODE
+                                : BC_CHECK_NOT_BACK_REF_NO_CASE),
+       start_reg);
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::IfRegisterLT(int register_index, int comparand,
+                                           Label* on_less_than) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_CHECK_REGISTER_LT, register_index);
+  Emit32(comparand);
+  EmitOrLink(on_less_than);
+}
+
+void RegExpBytecodeGenerator::IfRegisterGE(int register_index, int comparand,
+                                           Label* on_greater_or_equal) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_CHECK_REGISTER_GE, register_index);
+  Emit32(comparand);
+  EmitOrLink(on_greater_or_equal);
+}
+
+void RegExpBytecodeGenerator::IfRegisterEqPos(int register_index,
+                                              Label* on_eq) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_CHECK_REGISTER_EQ_POS, register_index);
+  EmitOrLink(on_eq);
+}
+
+Handle<HeapObject> RegExpBytecodeGenerator::GetCode(Handle<String> source) {
+  Bind(&backtrack_);
+  Emit(BC_POP_BT, 0);
+
+  Handle<ByteArray> array;
+  if (FLAG_regexp_peephole_optimization) {
+    array = RegExpBytecodePeepholeOptimization::OptimizeBytecode(
+        isolate_, zone(), source, buffer_.begin(), length(), jump_edges_);
+  } else {
+    array = isolate_->factory()->NewByteArray(length());
+    Copy(array->GetDataStartAddress());
+  }
+
+  return array;
+}
+
+int RegExpBytecodeGenerator::length() { return pc_; }
+
+void RegExpBytecodeGenerator::Copy(byte* a) {
+  MemCopy(a, buffer_.begin(), length());
+}
+
+void RegExpBytecodeGenerator::Expand() {
+  Vector<byte> old_buffer = buffer_;
+  buffer_ = Vector<byte>::New(old_buffer.length() * 2);
+  MemCopy(buffer_.begin(), old_buffer.begin(), old_buffer.length());
+  old_buffer.Dispose();
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-bytecode-generator.h b/js/src/regexp/regexp-bytecode-generator.h
new file mode 100644
index 0000000000..15fbda8ecb
--- /dev/null
+++ b/js/src/regexp/regexp-bytecode-generator.h
@@ -0,0 +1,119 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_BYTECODE_GENERATOR_H_
+#define V8_REGEXP_REGEXP_BYTECODE_GENERATOR_H_
+
+#include "regexp/regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+// An assembler/generator for the Irregexp byte code.
+class V8_EXPORT_PRIVATE RegExpBytecodeGenerator : public RegExpMacroAssembler {
+ public:
+  // Create an assembler. Instructions and relocation information are emitted
+  // into a buffer, with the instructions starting from the beginning and the
+  // relocation information starting from the end of the buffer. See CodeDesc
+  // for a detailed comment on the layout (globals.h).
+  //
+  // The assembler allocates and grows its own buffer, and buffer_size
+  // determines the initial buffer size. The buffer is owned by the assembler
+  // and deallocated upon destruction of the assembler.
+  RegExpBytecodeGenerator(Isolate* isolate, Zone* zone);
+  virtual ~RegExpBytecodeGenerator();
+  // The byte-code interpreter checks on each push anyway.
+  virtual int stack_limit_slack() { return 1; }
+  virtual bool CanReadUnaligned() { return false; }
+  virtual void Bind(Label* label);
+  virtual void AdvanceCurrentPosition(int by);  // Signed cp change.
+  virtual void PopCurrentPosition();
+  virtual void PushCurrentPosition();
+  virtual void Backtrack();
+  virtual void GoTo(Label* label);
+  virtual void PushBacktrack(Label* label);
+  virtual bool Succeed();
+  virtual void Fail();
+  virtual void PopRegister(int register_index);
+  virtual void PushRegister(int register_index,
+                            StackCheckFlag check_stack_limit);
+  virtual void AdvanceRegister(int reg, int by);  // r[reg] += by.
+  virtual void SetCurrentPositionFromEnd(int by);
+  virtual void SetRegister(int register_index, int to);
+  virtual void WriteCurrentPositionToRegister(int reg, int cp_offset);
+  virtual void ClearRegisters(int reg_from, int reg_to);
+  virtual void ReadCurrentPositionFromRegister(int reg);
+  virtual void WriteStackPointerToRegister(int reg);
+  virtual void ReadStackPointerFromRegister(int reg);
+  virtual void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
+                                        bool check_bounds, int characters,
+                                        int eats_at_least);
+  virtual void CheckCharacter(unsigned c, Label* on_equal);
+  virtual void CheckCharacterAfterAnd(unsigned c, unsigned mask,
+                                      Label* on_equal);
+  virtual void CheckCharacterGT(uc16 limit, Label* on_greater);
+  virtual void CheckCharacterLT(uc16 limit, Label* on_less);
+  virtual void CheckGreedyLoop(Label* on_tos_equals_current_position);
+  virtual void CheckAtStart(int cp_offset, Label* on_at_start);
+  virtual void CheckNotAtStart(int cp_offset, Label* on_not_at_start);
+  virtual void CheckNotCharacter(unsigned c, Label* on_not_equal);
+  virtual void CheckNotCharacterAfterAnd(unsigned c, unsigned mask,
+                                         Label* on_not_equal);
+  virtual void CheckNotCharacterAfterMinusAnd(uc16 c, uc16 minus, uc16 mask,
+                                              Label* on_not_equal);
+  virtual void CheckCharacterInRange(uc16 from, uc16 to, Label* on_in_range);
+  virtual void CheckCharacterNotInRange(uc16 from, uc16 to,
+                                        Label* on_not_in_range);
+  virtual void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set);
+  virtual void CheckNotBackReference(int start_reg, bool read_backward,
+                                     Label* on_no_match);
+  virtual void CheckNotBackReferenceIgnoreCase(int start_reg,
+                                               bool read_backward, bool unicode,
+                                               Label* on_no_match);
+  virtual void IfRegisterLT(int register_index, int comparand, Label* if_lt);
+  virtual void IfRegisterGE(int register_index, int comparand, Label* if_ge);
+  virtual void IfRegisterEqPos(int register_index, Label* if_eq);
+
+  virtual IrregexpImplementation Implementation();
+  virtual Handle<HeapObject> GetCode(Handle<String> source);
+
+ private:
+  void Expand();
+  // Code and bitmap emission.
+  inline void EmitOrLink(Label* label);
+  inline void Emit32(uint32_t x);
+  inline void Emit16(uint32_t x);
+  inline void Emit8(uint32_t x);
+  inline void Emit(uint32_t bc, uint32_t arg);
+  // Bytecode buffer.
+  int length();
+  void Copy(byte* a);
+
+  // The buffer into which code and relocation info are generated.
+  Vector<byte> buffer_;
+  // The program counter.
+  int pc_;
+  Label backtrack_;
+
+  int advance_current_start_;
+  int advance_current_offset_;
+  int advance_current_end_;
+
+  // Stores jump edges emitted for the bytecode (used by
+  // RegExpBytecodePeepholeOptimization).
+  // Key: jump source (offset in buffer_ where jump destination is stored).
+  // Value: jump destination (offset in buffer_ to jump to).
+  ZoneUnorderedMap<int, int> jump_edges_;
+
+  Isolate* isolate_;
+
+  static const int kInvalidPC = -1;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpBytecodeGenerator);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_BYTECODE_GENERATOR_H_
diff --git a/js/src/regexp/regexp-bytecode-peephole.cc b/js/src/regexp/regexp-bytecode-peephole.cc
new file mode 100644
index 0000000000..2bc1b5aa26
--- /dev/null
+++ b/js/src/regexp/regexp-bytecode-peephole.cc
@@ -0,0 +1,1029 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-bytecode-peephole.h"
+
+#include "regexp/regexp-bytecodes.h"
+
+namespace v8 {
+namespace internal {
+
+namespace {
+
+struct BytecodeArgument {
+  int offset;
+  int length;
+
+  BytecodeArgument(int offset, int length) : offset(offset), length(length) {}
+};
+
+struct BytecodeArgumentMapping : BytecodeArgument {
+  int new_length;
+
+  BytecodeArgumentMapping(int offset, int length, int new_length)
+      : BytecodeArgument(offset, length), new_length(new_length) {}
+};
+
+struct BytecodeArgumentCheck : BytecodeArgument {
+  enum CheckType { kCheckAddress = 0, kCheckValue };
+  CheckType type;
+  int check_offset;
+  int check_length;
+
+  BytecodeArgumentCheck(int offset, int length, int check_offset)
+      : BytecodeArgument(offset, length),
+        type(kCheckAddress),
+        check_offset(check_offset) {}
+  BytecodeArgumentCheck(int offset, int length, int check_offset,
+                        int check_length)
+      : BytecodeArgument(offset, length),
+        type(kCheckValue),
+        check_offset(check_offset),
+        check_length(check_length) {}
+};
+
+// Trie-Node for storing bytecode sequences we want to optimize.
+class BytecodeSequenceNode {
+ public:
+  // Dummy bytecode used when we need to store/return a bytecode but it's not a
+  // valid bytecode in the current context.
+  static constexpr int kDummyBytecode = -1;
+
+  BytecodeSequenceNode(int bytecode, Zone* zone);
+  // Adds a new node as child of the current node if it isn't a child already.
+  BytecodeSequenceNode& FollowedBy(int bytecode);
+  // Marks the end of a sequence and sets optimized bytecode to replace all
+  // bytecodes of the sequence with.
+  BytecodeSequenceNode& ReplaceWith(int bytecode);
+  // Maps arguments of bytecodes in the sequence to the optimized bytecode.
+  // Order of invocation determines order of arguments in the optimized
+  // bytecode.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. after ReplaceWith()).
+  // bytecode_index_in_sequence: Zero-based index of the referred bytecode
+  // within the sequence (e.g. the bytecode passed to CreateSequence() has
+  // index 0).
+  // argument_offset: Zero-based offset to the argument within the bytecode
+  // (e.g. the first argument that's not packed with the bytecode has offset 4).
+  // argument_byte_length: Length of the argument.
+  // new_argument_byte_length: Length of the argument in the new bytecode
+  // (= argument_byte_length if omitted).
+  BytecodeSequenceNode& MapArgument(int bytecode_index_in_sequence,
+                                    int argument_offset,
+                                    int argument_byte_length,
+                                    int new_argument_byte_length = 0);
+  // Adds a check to the sequence node making it only a valid sequence when the
+  // argument of the current bytecode at the specified offset matches the offset
+  // to check against.
+  // argument_offset: Zero-based offset to the argument within the bytecode
+  // (e.g. the first argument that's not packed with the bytecode has offset 4).
+  // argument_byte_length: Length of the argument.
+  // check_byte_offset: Zero-based offset relative to the beginning of the
+  // sequence that needs to match the value given by argument_offset. (e.g.
+  // check_byte_offset 0 matches the address of the first bytecode in the
+  // sequence).
+  BytecodeSequenceNode& IfArgumentEqualsOffset(int argument_offset,
+                                               int argument_byte_length,
+                                               int check_byte_offset);
+  // Adds a check to the sequence node making it only a valid sequence when the
+  // argument of the current bytecode at the specified offset matches the
+  // argument of another bytecode in the sequence.
+  // This is similar to IfArgumentEqualsOffset, except that this method matches
+  // the values of both arguments.
+  BytecodeSequenceNode& IfArgumentEqualsValueAtOffset(
+      int argument_offset, int argument_byte_length,
+      int other_bytecode_index_in_sequence, int other_argument_offset,
+      int other_argument_byte_length);
+  // Marks an argument as unused.
+  // All arguments that are not mapped explicitly have to be marked as unused.
+  // bytecode_index_in_sequence: Zero-based index of the referred bytecode
+  // within the sequence (e.g. the bytecode passed to CreateSequence() has
+  // index 0).
+  // argument_offset: Zero-based offset to the argument within the bytecode
+  // (e.g. the first argument that's not packed with the bytecode has offset 4).
+  // argument_byte_length: Length of the argument.
+  BytecodeSequenceNode& IgnoreArgument(int bytecode_index_in_sequence,
+                                       int argument_offset,
+                                       int argument_byte_length);
+  // Checks if the current node is valid for the sequence. I.e. all conditions
+  // set by IfArgumentEqualsOffset and IfArgumentEquals are fulfilled by this
+  // node for the actual bytecode sequence.
+  bool CheckArguments(const byte* bytecode, int pc);
+  // Returns whether this node marks the end of a valid sequence (i.e. can be
+  // replaced with an optimized bytecode).
+  bool IsSequence() const;
+  // Returns the length of the sequence in bytes.
+  int SequenceLength() const;
+  // Returns the optimized bytecode for the node or kDummyBytecode if it is not
+  // the end of a valid sequence.
+  int OptimizedBytecode() const;
+  // Returns the child of the current node matching the given bytecode or
+  // nullptr if no such child is found.
+  BytecodeSequenceNode* Find(int bytecode) const;
+  // Returns number of arguments mapped to the current node.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. if IsSequence())
+  size_t ArgumentSize() const;
+  // Returns the argument-mapping of the argument at index.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. if IsSequence())
+  BytecodeArgumentMapping ArgumentMapping(size_t index) const;
+  // Returns an iterator to begin of ignored arguments.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. if IsSequence())
+  ZoneLinkedList<BytecodeArgument>::iterator ArgumentIgnoredBegin() const;
+  // Returns an iterator to end of ignored arguments.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. if IsSequence())
+  ZoneLinkedList<BytecodeArgument>::iterator ArgumentIgnoredEnd() const;
+  // Returns whether the current node has ignored argument or not.
+  bool HasIgnoredArguments() const;
+
+ private:
+  // Returns a node in the sequence specified by its index within the sequence.
+  BytecodeSequenceNode& GetNodeByIndexInSequence(int index_in_sequence);
+  Zone* zone() const;
+
+  int bytecode_;
+  int bytecode_replacement_;
+  int index_in_sequence_;
+  int start_offset_;
+  BytecodeSequenceNode* parent_;
+  ZoneUnorderedMap<int, BytecodeSequenceNode*> children_;
+  ZoneVector<BytecodeArgumentMapping>* argument_mapping_;
+  ZoneLinkedList<BytecodeArgumentCheck>* argument_check_;
+  ZoneLinkedList<BytecodeArgument>* argument_ignored_;
+
+  Zone* zone_;
+};
+
+class RegExpBytecodePeephole {
+ public:
+  RegExpBytecodePeephole(Zone* zone, size_t buffer_size,
+                         const ZoneUnorderedMap<int, int>& jump_edges);
+
+  // Parses bytecode and fills the internal buffer with the potentially
+  // optimized bytecode. Returns true when optimizations were performed, false
+  // otherwise.
+  bool OptimizeBytecode(const byte* bytecode, int length);
+  // Copies the internal bytecode buffer to another buffer. The caller is
+  // responsible for allocating/freeing the memory.
+  void CopyOptimizedBytecode(byte* to_address) const;
+  int Length() const;
+
+ private:
+  // Sets up all sequences that are going to be used.
+  void DefineStandardSequences();
+  // Starts a new bytecode sequence.
+  BytecodeSequenceNode& CreateSequence(int bytecode);
+  // Checks for optimization candidates at pc and emits optimized bytecode to
+  // the internal buffer. Returns the length of replaced bytecodes in bytes.
+  int TryOptimizeSequence(const byte* bytecode, int start_pc);
+  // Emits optimized bytecode to the internal buffer. start_pc points to the
+  // start of the sequence in bytecode and last_node is the last
+  // BytecodeSequenceNode of the matching sequence found.
+  void EmitOptimization(int start_pc, const byte* bytecode,
+                        const BytecodeSequenceNode& last_node);
+  // Adds a relative jump source fixup at pos.
+  // Jump source fixups are used to find offsets in the new bytecode that
+  // contain jump sources.
+  void AddJumpSourceFixup(int fixup, int pos);
+  // Adds a relative jump destination fixup at pos.
+  // Jump destination fixups are used to find offsets in the new bytecode that
+  // can be jumped to.
+  void AddJumpDestinationFixup(int fixup, int pos);
+  // Sets an absolute jump destination fixup at pos.
+  void SetJumpDestinationFixup(int fixup, int pos);
+  // Prepare internal structures used to fixup jumps.
+  void PrepareJumpStructures(const ZoneUnorderedMap<int, int>& jump_edges);
+  // Updates all jump targets in the new bytecode.
+  void FixJumps();
+  // Update a single jump.
+  void FixJump(int jump_source, int jump_destination);
+  void AddSentinelFixups(int pos);
+  template <typename T>
+  void EmitValue(T value);
+  template <typename T>
+  void OverwriteValue(int offset, T value);
+  void CopyRangeToOutput(const byte* orig_bytecode, int start, int length);
+  void SetRange(byte value, int count);
+  void EmitArgument(int start_pc, const byte* bytecode,
+                    BytecodeArgumentMapping arg);
+  int pc() const;
+  Zone* zone() const;
+
+  ZoneVector<byte> optimized_bytecode_buffer_;
+  BytecodeSequenceNode* sequences_;
+  // Jumps used in old bytecode.
+  // Key: Jump source (offset where destination is stored in old bytecode)
+  // Value: Destination
+  ZoneMap<int, int> jump_edges_;
+  // Jumps used in new bytecode.
+  // Key: Jump source (offset where destination is stored in new bytecode)
+  // Value: Destination
+  ZoneMap<int, int> jump_edges_mapped_;
+  // Number of times a jump destination is used within the bytecode.
+  // Key: Jump destination (offset in old bytecode).
+  // Value: Number of times jump destination is used.
+  ZoneMap<int, int> jump_usage_counts_;
+  // Maps offsets in old bytecode to fixups of sources (delta to new bytecode).
+  // Key: Offset in old bytecode from where the fixup is valid.
+  // Value: Delta to map jump source from old bytecode to new bytecode in bytes.
+  ZoneMap<int, int> jump_source_fixups_;
+  // Maps offsets in old bytecode to fixups of destinations (delta to new
+  // bytecode).
+  // Key: Offset in old bytecode from where the fixup is valid.
+  // Value: Delta to map jump destinations from old bytecode to new bytecode in
+  // bytes.
+  ZoneMap<int, int> jump_destination_fixups_;
+
+  Zone* zone_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpBytecodePeephole);
+};
+
+template <typename T>
+T GetValue(const byte* buffer, int pos) {
+  DCHECK(IsAligned(reinterpret_cast<Address>(buffer + pos), alignof(T)));
+  return *reinterpret_cast<const T*>(buffer + pos);
+}
+
+int32_t GetArgumentValue(const byte* bytecode, int offset, int length) {
+  switch (length) {
+    case 1:
+      return GetValue<byte>(bytecode, offset);
+      break;
+    case 2:
+      return GetValue<int16_t>(bytecode, offset);
+      break;
+    case 4:
+      return GetValue<int32_t>(bytecode, offset);
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+BytecodeSequenceNode::BytecodeSequenceNode(int bytecode, Zone* zone)
+    : bytecode_(bytecode),
+      bytecode_replacement_(kDummyBytecode),
+      index_in_sequence_(0),
+      start_offset_(0),
+      parent_(nullptr),
+      children_(ZoneUnorderedMap<int, BytecodeSequenceNode*>(zone)),
+      argument_mapping_(new (zone->New(sizeof(*argument_mapping_)))
+                            ZoneVector<BytecodeArgumentMapping>(zone)),
+      argument_check_(new (zone->New(sizeof(*argument_check_)))
+                          ZoneLinkedList<BytecodeArgumentCheck>(zone)),
+      argument_ignored_(new (zone->New(sizeof(*argument_ignored_)))
+                            ZoneLinkedList<BytecodeArgument>(zone)),
+      zone_(zone) {}
+
+BytecodeSequenceNode& BytecodeSequenceNode::FollowedBy(int bytecode) {
+  DCHECK(0 <= bytecode && bytecode < kRegExpBytecodeCount);
+
+  if (children_.find(bytecode) == children_.end()) {
+    BytecodeSequenceNode* new_node =
+        new (zone()->New(sizeof(BytecodeSequenceNode)))
+            BytecodeSequenceNode(bytecode, zone());
+    // If node is not the first in the sequence, set offsets and parent.
+    if (bytecode_ != kDummyBytecode) {
+      new_node->start_offset_ = start_offset_ + RegExpBytecodeLength(bytecode_);
+      new_node->index_in_sequence_ = index_in_sequence_ + 1;
+      new_node->parent_ = this;
+    }
+    children_[bytecode] = new_node;
+  }
+
+  return *children_[bytecode];
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::ReplaceWith(int bytecode) {
+  DCHECK(0 <= bytecode && bytecode < kRegExpBytecodeCount);
+
+  bytecode_replacement_ = bytecode;
+
+  return *this;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::MapArgument(
+    int bytecode_index_in_sequence, int argument_offset,
+    int argument_byte_length, int new_argument_byte_length) {
+  DCHECK(IsSequence());
+  DCHECK_LE(bytecode_index_in_sequence, index_in_sequence_);
+
+  BytecodeSequenceNode& ref_node =
+      GetNodeByIndexInSequence(bytecode_index_in_sequence);
+  DCHECK_LT(argument_offset, RegExpBytecodeLength(ref_node.bytecode_));
+
+  int absolute_offset = ref_node.start_offset_ + argument_offset;
+  if (new_argument_byte_length == 0) {
+    new_argument_byte_length = argument_byte_length;
+  }
+
+  argument_mapping_->push_back(BytecodeArgumentMapping{
+      absolute_offset, argument_byte_length, new_argument_byte_length});
+
+  return *this;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::IfArgumentEqualsOffset(
+    int argument_offset, int argument_byte_length, int check_byte_offset) {
+  DCHECK_LT(argument_offset, RegExpBytecodeLength(bytecode_));
+  DCHECK(argument_byte_length == 1 || argument_byte_length == 2 ||
+         argument_byte_length == 4);
+
+  int absolute_offset = start_offset_ + argument_offset;
+
+  argument_check_->push_back(BytecodeArgumentCheck{
+      absolute_offset, argument_byte_length, check_byte_offset});
+
+  return *this;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::IfArgumentEqualsValueAtOffset(
+    int argument_offset, int argument_byte_length,
+    int other_bytecode_index_in_sequence, int other_argument_offset,
+    int other_argument_byte_length) {
+  DCHECK_LT(argument_offset, RegExpBytecodeLength(bytecode_));
+  DCHECK_LE(other_bytecode_index_in_sequence, index_in_sequence_);
+  DCHECK_EQ(argument_byte_length, other_argument_byte_length);
+
+  BytecodeSequenceNode& ref_node =
+      GetNodeByIndexInSequence(other_bytecode_index_in_sequence);
+  DCHECK_LT(other_argument_offset, RegExpBytecodeLength(ref_node.bytecode_));
+
+  int absolute_offset = start_offset_ + argument_offset;
+  int other_absolute_offset = ref_node.start_offset_ + other_argument_offset;
+
+  argument_check_->push_back(
+      BytecodeArgumentCheck{absolute_offset, argument_byte_length,
+                            other_absolute_offset, other_argument_byte_length});
+
+  return *this;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::IgnoreArgument(
+    int bytecode_index_in_sequence, int argument_offset,
+    int argument_byte_length) {
+  DCHECK(IsSequence());
+  DCHECK_LE(bytecode_index_in_sequence, index_in_sequence_);
+
+  BytecodeSequenceNode& ref_node =
+      GetNodeByIndexInSequence(bytecode_index_in_sequence);
+  DCHECK_LT(argument_offset, RegExpBytecodeLength(ref_node.bytecode_));
+
+  int absolute_offset = ref_node.start_offset_ + argument_offset;
+
+  argument_ignored_->push_back(
+      BytecodeArgument{absolute_offset, argument_byte_length});
+
+  return *this;
+}
+
+bool BytecodeSequenceNode::CheckArguments(const byte* bytecode, int pc) {
+  bool is_valid = true;
+  for (auto check_iter = argument_check_->begin();
+       check_iter != argument_check_->end() && is_valid; check_iter++) {
+    auto value =
+        GetArgumentValue(bytecode, pc + check_iter->offset, check_iter->length);
+    if (check_iter->type == BytecodeArgumentCheck::kCheckAddress) {
+      is_valid &= value == pc + check_iter->check_offset;
+    } else if (check_iter->type == BytecodeArgumentCheck::kCheckValue) {
+      auto other_value = GetArgumentValue(
+          bytecode, pc + check_iter->check_offset, check_iter->check_length);
+      is_valid &= value == other_value;
+    } else {
+      UNREACHABLE();
+    }
+  }
+  return is_valid;
+}
+
+bool BytecodeSequenceNode::IsSequence() const {
+  return bytecode_replacement_ != kDummyBytecode;
+}
+
+int BytecodeSequenceNode::SequenceLength() const {
+  return start_offset_ + RegExpBytecodeLength(bytecode_);
+}
+
+int BytecodeSequenceNode::OptimizedBytecode() const {
+  return bytecode_replacement_;
+}
+
+BytecodeSequenceNode* BytecodeSequenceNode::Find(int bytecode) const {
+  auto found = children_.find(bytecode);
+  if (found == children_.end()) return nullptr;
+  return found->second;
+}
+
+size_t BytecodeSequenceNode::ArgumentSize() const {
+  DCHECK(IsSequence());
+  return argument_mapping_->size();
+}
+
+BytecodeArgumentMapping BytecodeSequenceNode::ArgumentMapping(
+    size_t index) const {
+  DCHECK(IsSequence());
+  DCHECK(argument_mapping_ != nullptr);
+  DCHECK_GE(index, 0);
+  DCHECK_LT(index, argument_mapping_->size());
+
+  return argument_mapping_->at(index);
+}
+
+ZoneLinkedList<BytecodeArgument>::iterator
+BytecodeSequenceNode::ArgumentIgnoredBegin() const {
+  DCHECK(IsSequence());
+  DCHECK(argument_ignored_ != nullptr);
+  return argument_ignored_->begin();
+}
+
+ZoneLinkedList<BytecodeArgument>::iterator
+BytecodeSequenceNode::ArgumentIgnoredEnd() const {
+  DCHECK(IsSequence());
+  DCHECK(argument_ignored_ != nullptr);
+  return argument_ignored_->end();
+}
+
+bool BytecodeSequenceNode::HasIgnoredArguments() const {
+  return argument_ignored_ != nullptr;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::GetNodeByIndexInSequence(
+    int index_in_sequence) {
+  DCHECK_LE(index_in_sequence, index_in_sequence_);
+
+  if (index_in_sequence < index_in_sequence_) {
+    DCHECK(parent_ != nullptr);
+    return parent_->GetNodeByIndexInSequence(index_in_sequence);
+  } else {
+    return *this;
+  }
+}
+
+Zone* BytecodeSequenceNode::zone() const { return zone_; }
+
+RegExpBytecodePeephole::RegExpBytecodePeephole(
+    Zone* zone, size_t buffer_size,
+    const ZoneUnorderedMap<int, int>& jump_edges)
+    : optimized_bytecode_buffer_(zone),
+      sequences_(new (zone->New(sizeof(*sequences_))) BytecodeSequenceNode(
+          BytecodeSequenceNode::kDummyBytecode, zone)),
+      jump_edges_(zone),
+      jump_edges_mapped_(zone),
+      jump_usage_counts_(zone),
+      jump_source_fixups_(zone),
+      jump_destination_fixups_(zone),
+      zone_(zone) {
+  optimized_bytecode_buffer_.reserve(buffer_size);
+  PrepareJumpStructures(jump_edges);
+  DefineStandardSequences();
+  // Sentinel fixups at beginning of bytecode (position -1) so we don't have to
+  // check for end of iterator inside the fixup loop.
+  // In general fixups are deltas of original offsets of jump
+  // sources/destinations (in the old bytecode) to find them in the new
+  // bytecode. All jump targets are fixed after the new bytecode is fully
+  // emitted in the internal buffer.
+  AddSentinelFixups(-1);
+  // Sentinel fixups at end of (old) bytecode so we don't have to check for
+  // end of iterator inside the fixup loop.
+  DCHECK_LE(buffer_size, std::numeric_limits<int>::max());
+  AddSentinelFixups(static_cast<int>(buffer_size));
+}
+
+void RegExpBytecodePeephole::DefineStandardSequences() {
+  // Commonly used sequences can be found by creating regexp bytecode traces
+  // (--trace-regexp-bytecodes) and using v8/tools/regexp-sequences.py.
+  CreateSequence(BC_LOAD_CURRENT_CHAR)
+      .FollowedBy(BC_CHECK_BIT_IN_TABLE)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_BIT_IN_TABLE)
+      .MapArgument(0, 1, 3)      // load offset
+      .MapArgument(2, 1, 3, 4)   // advance by
+      .MapArgument(1, 8, 16)     // bit table
+      .MapArgument(1, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(2, 4, 4);  // loop jump
+
+  CreateSequence(BC_CHECK_CURRENT_POSITION)
+      .FollowedBy(BC_LOAD_CURRENT_CHAR_UNCHECKED)
+      .FollowedBy(BC_CHECK_CHAR)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_CHAR_POS_CHECKED)
+      .MapArgument(1, 1, 3)      // load offset
+      .MapArgument(3, 1, 3, 2)   // advance_by
+      .MapArgument(2, 1, 3, 2)   // c
+      .MapArgument(0, 1, 3, 4)   // eats at least
+      .MapArgument(2, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(3, 4, 4);  // loop jump
+
+  CreateSequence(BC_CHECK_CURRENT_POSITION)
+      .FollowedBy(BC_LOAD_CURRENT_CHAR_UNCHECKED)
+      .FollowedBy(BC_AND_CHECK_CHAR)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_CHAR_AND)
+      .MapArgument(1, 1, 3)      // load offset
+      .MapArgument(3, 1, 3, 2)   // advance_by
+      .MapArgument(2, 1, 3, 2)   // c
+      .MapArgument(2, 4, 4)      // mask
+      .MapArgument(0, 1, 3, 4)   // eats at least
+      .MapArgument(2, 8, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(3, 4, 4);  // loop jump
+
+  // TODO(pthier): It might make sense for short sequences like this one to only
+  // optimize them if the resulting optimization is not longer than the current
+  // one. This could be the case if there are jumps inside the sequence and we
+  // have to replicate parts of the sequence. A method to mark such sequences
+  // might be useful.
+  CreateSequence(BC_LOAD_CURRENT_CHAR)
+      .FollowedBy(BC_CHECK_CHAR)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_CHAR)
+      .MapArgument(0, 1, 3)      // load offset
+      .MapArgument(2, 1, 3, 2)   // advance by
+      .MapArgument(1, 1, 3, 2)   // character
+      .MapArgument(1, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(2, 4, 4);  // loop jump
+
+  CreateSequence(BC_LOAD_CURRENT_CHAR)
+      .FollowedBy(BC_CHECK_CHAR)
+      .FollowedBy(BC_CHECK_CHAR)
+      // Sequence is only valid if the jump targets of both CHECK_CHAR bytecodes
+      // are equal.
+      .IfArgumentEqualsValueAtOffset(4, 4, 1, 4, 4)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_CHAR_OR_CHAR)
+      .MapArgument(0, 1, 3)      // load offset
+      .MapArgument(3, 1, 3, 4)   // advance by
+      .MapArgument(1, 1, 3, 2)   // character 1
+      .MapArgument(2, 1, 3, 2)   // character 2
+      .MapArgument(1, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(2, 4, 4)   // goto when match 2
+      .IgnoreArgument(3, 4, 4);  // loop jump
+
+  CreateSequence(BC_LOAD_CURRENT_CHAR)
+      .FollowedBy(BC_CHECK_GT)
+      // Sequence is only valid if the jump target of CHECK_GT is the first
+      // bytecode AFTER the whole sequence.
+      .IfArgumentEqualsOffset(4, 4, 56)
+      .FollowedBy(BC_CHECK_BIT_IN_TABLE)
+      // Sequence is only valid if the jump target of CHECK_BIT_IN_TABLE is
+      // the ADVANCE_CP_AND_GOTO bytecode at the end of the sequence.
+      .IfArgumentEqualsOffset(4, 4, 48)
+      .FollowedBy(BC_GOTO)
+      // Sequence is only valid if the jump target of GOTO is the same as the
+      // jump target of CHECK_GT (i.e. both jump to the first bytecode AFTER the
+      // whole sequence.
+      .IfArgumentEqualsValueAtOffset(4, 4, 1, 4, 4)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_GT_OR_NOT_BIT_IN_TABLE)
+      .MapArgument(0, 1, 3)      // load offset
+      .MapArgument(4, 1, 3, 2)   // advance by
+      .MapArgument(1, 1, 3, 2)   // character
+      .MapArgument(2, 8, 16)     // bit table
+      .MapArgument(1, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(2, 4, 4)   // indirect loop jump
+      .IgnoreArgument(3, 4, 4)   // jump out of loop
+      .IgnoreArgument(4, 4, 4);  // loop jump
+}
+
+bool RegExpBytecodePeephole::OptimizeBytecode(const byte* bytecode,
+                                              int length) {
+  int old_pc = 0;
+  bool did_optimize = false;
+
+  while (old_pc < length) {
+    int replaced_len = TryOptimizeSequence(bytecode, old_pc);
+    if (replaced_len > 0) {
+      old_pc += replaced_len;
+      did_optimize = true;
+    } else {
+      int bc = bytecode[old_pc];
+      int bc_len = RegExpBytecodeLength(bc);
+      CopyRangeToOutput(bytecode, old_pc, bc_len);
+      old_pc += bc_len;
+    }
+  }
+
+  if (did_optimize) {
+    FixJumps();
+  }
+
+  return did_optimize;
+}
+
+void RegExpBytecodePeephole::CopyOptimizedBytecode(byte* to_address) const {
+  MemCopy(to_address, &(*optimized_bytecode_buffer_.begin()), Length());
+}
+
+int RegExpBytecodePeephole::Length() const { return pc(); }
+
+BytecodeSequenceNode& RegExpBytecodePeephole::CreateSequence(int bytecode) {
+  DCHECK(sequences_ != nullptr);
+  DCHECK(0 <= bytecode && bytecode < kRegExpBytecodeCount);
+
+  return sequences_->FollowedBy(bytecode);
+}
+
+int RegExpBytecodePeephole::TryOptimizeSequence(const byte* bytecode,
+                                                int start_pc) {
+  BytecodeSequenceNode* seq_node = sequences_;
+  BytecodeSequenceNode* valid_seq_end = nullptr;
+
+  int current_pc = start_pc;
+
+  // Check for the longest valid sequence matching any of the pre-defined
+  // sequences in the Trie data structure.
+  while ((seq_node = seq_node->Find(bytecode[current_pc]))) {
+    if (!seq_node->CheckArguments(bytecode, start_pc)) {
+      break;
+    }
+    if (seq_node->IsSequence()) {
+      valid_seq_end = seq_node;
+    }
+    current_pc += RegExpBytecodeLength(bytecode[current_pc]);
+  }
+
+  if (valid_seq_end) {
+    EmitOptimization(start_pc, bytecode, *valid_seq_end);
+    return valid_seq_end->SequenceLength();
+  }
+
+  return 0;
+}
+
+void RegExpBytecodePeephole::EmitOptimization(
+    int start_pc, const byte* bytecode, const BytecodeSequenceNode& last_node) {
+#ifdef DEBUG
+  int optimized_start_pc = pc();
+#endif
+  // Jump sources that are mapped or marked as unused will be deleted at the end
+  // of this method. We don't delete them immediately as we might need the
+  // information when we have to preserve bytecodes at the end.
+  // TODO(pthier): Replace with a stack-allocated data structure.
+  ZoneLinkedList<int> delete_jumps = ZoneLinkedList<int>(zone());
+
+  uint32_t bc = last_node.OptimizedBytecode();
+  EmitValue(bc);
+
+  for (size_t arg = 0; arg < last_node.ArgumentSize(); arg++) {
+    BytecodeArgumentMapping arg_map = last_node.ArgumentMapping(arg);
+    int arg_pos = start_pc + arg_map.offset;
+    // If we map any jump source we mark the old source for deletion and insert
+    // a new jump.
+    auto jump_edge_iter = jump_edges_.find(arg_pos);
+    if (jump_edge_iter != jump_edges_.end()) {
+      int jump_source = jump_edge_iter->first;
+      int jump_destination = jump_edge_iter->second;
+      // Add new jump edge add current position.
+      jump_edges_mapped_.emplace(Length(), jump_destination);
+      // Mark old jump edge for deletion.
+      delete_jumps.push_back(jump_source);
+      // Decrement usage count of jump destination.
+      auto jump_count_iter = jump_usage_counts_.find(jump_destination);
+      DCHECK(jump_count_iter != jump_usage_counts_.end());
+      int& usage_count = jump_count_iter->second;
+      --usage_count;
+    }
+    // TODO(pthier): DCHECK that mapped arguments are never sources of jumps
+    // to destinations inside the sequence.
+    EmitArgument(start_pc, bytecode, arg_map);
+  }
+  DCHECK_EQ(pc(), optimized_start_pc +
+                      RegExpBytecodeLength(last_node.OptimizedBytecode()));
+
+  // Remove jumps from arguments we ignore.
+  if (last_node.HasIgnoredArguments()) {
+    for (auto ignored_arg = last_node.ArgumentIgnoredBegin();
+         ignored_arg != last_node.ArgumentIgnoredEnd(); ignored_arg++) {
+      auto jump_edge_iter = jump_edges_.find(start_pc + ignored_arg->offset);
+      if (jump_edge_iter != jump_edges_.end()) {
+        int jump_source = jump_edge_iter->first;
+        int jump_destination = jump_edge_iter->second;
+        // Mark old jump edge for deletion.
+        delete_jumps.push_back(jump_source);
+        // Decrement usage count of jump destination.
+        auto jump_count_iter = jump_usage_counts_.find(jump_destination);
+        DCHECK(jump_count_iter != jump_usage_counts_.end());
+        int& usage_count = jump_count_iter->second;
+        --usage_count;
+      }
+    }
+  }
+
+  int fixup_length = RegExpBytecodeLength(bc) - last_node.SequenceLength();
+
+  // Check if there are any jumps inside the old sequence.
+  // If so we have to keep the bytecodes that are jumped to around.
+  auto jump_destination_candidate = jump_usage_counts_.upper_bound(start_pc);
+  int jump_candidate_destination = jump_destination_candidate->first;
+  int jump_candidate_count = jump_destination_candidate->second;
+  // Jump destinations only jumped to from inside the sequence will be ignored.
+  while (jump_destination_candidate != jump_usage_counts_.end() &&
+         jump_candidate_count == 0) {
+    ++jump_destination_candidate;
+    jump_candidate_destination = jump_destination_candidate->first;
+    jump_candidate_count = jump_destination_candidate->second;
+  }
+
+  int preserve_from = start_pc + last_node.SequenceLength();
+  if (jump_destination_candidate != jump_usage_counts_.end() &&
+      jump_candidate_destination < start_pc + last_node.SequenceLength()) {
+    preserve_from = jump_candidate_destination;
+    // Check if any jump in the sequence we are preserving has a jump
+    // destination inside the optimized sequence before the current position we
+    // want to preserve. If so we have to preserve all bytecodes starting at
+    // this jump destination.
+    for (auto jump_iter = jump_edges_.lower_bound(preserve_from);
+         jump_iter != jump_edges_.end() &&
+         jump_iter->first /* jump source */ <
+             start_pc + last_node.SequenceLength();
+         ++jump_iter) {
+      int jump_destination = jump_iter->second;
+      if (jump_destination > start_pc && jump_destination < preserve_from) {
+        preserve_from = jump_destination;
+      }
+    }
+
+    // We preserve everything to the end of the sequence. This is conservative
+    // since it would be enough to preserve all bytecudes up to an unconditional
+    // jump.
+    int preserve_length = start_pc + last_node.SequenceLength() - preserve_from;
+    fixup_length += preserve_length;
+    // Jumps after the start of the preserved sequence need fixup.
+    AddJumpSourceFixup(fixup_length,
+                       start_pc + last_node.SequenceLength() - preserve_length);
+    // All jump targets after the start of the optimized sequence need to be
+    // fixed relative to the length of the optimized sequence including
+    // bytecodes we preserved.
+    AddJumpDestinationFixup(fixup_length, start_pc + 1);
+    // Jumps to the sequence we preserved need absolute fixup as they could
+    // occur before or after the sequence.
+    SetJumpDestinationFixup(pc() - preserve_from, preserve_from);
+    CopyRangeToOutput(bytecode, preserve_from, preserve_length);
+  } else {
+    AddJumpDestinationFixup(fixup_length, start_pc + 1);
+    // Jumps after the end of the old sequence need fixup.
+    AddJumpSourceFixup(fixup_length, start_pc + last_node.SequenceLength());
+  }
+
+  // Delete jumps we definitely don't need anymore
+  for (int del : delete_jumps) {
+    if (del < preserve_from) {
+      jump_edges_.erase(del);
+    }
+  }
+}
+
+void RegExpBytecodePeephole::AddJumpSourceFixup(int fixup, int pos) {
+  auto previous_fixup = jump_source_fixups_.lower_bound(pos);
+  DCHECK(previous_fixup != jump_source_fixups_.end());
+  DCHECK(previous_fixup != jump_source_fixups_.begin());
+
+  int previous_fixup_value = (--previous_fixup)->second;
+  jump_source_fixups_[pos] = previous_fixup_value + fixup;
+}
+
+void RegExpBytecodePeephole::AddJumpDestinationFixup(int fixup, int pos) {
+  auto previous_fixup = jump_destination_fixups_.lower_bound(pos);
+  DCHECK(previous_fixup != jump_destination_fixups_.end());
+  DCHECK(previous_fixup != jump_destination_fixups_.begin());
+
+  int previous_fixup_value = (--previous_fixup)->second;
+  jump_destination_fixups_[pos] = previous_fixup_value + fixup;
+}
+
+void RegExpBytecodePeephole::SetJumpDestinationFixup(int fixup, int pos) {
+  auto previous_fixup = jump_destination_fixups_.lower_bound(pos);
+  DCHECK(previous_fixup != jump_destination_fixups_.end());
+  DCHECK(previous_fixup != jump_destination_fixups_.begin());
+
+  int previous_fixup_value = (--previous_fixup)->second;
+  jump_destination_fixups_.emplace(pos, fixup);
+  jump_destination_fixups_.emplace(pos + 1, previous_fixup_value);
+}
+
+void RegExpBytecodePeephole::PrepareJumpStructures(
+    const ZoneUnorderedMap<int, int>& jump_edges) {
+  for (auto jump_edge : jump_edges) {
+    int jump_source = jump_edge.first;
+    int jump_destination = jump_edge.second;
+
+    jump_edges_.emplace(jump_source, jump_destination);
+    jump_usage_counts_[jump_destination]++;
+  }
+}
+
+void RegExpBytecodePeephole::FixJumps() {
+  int position_fixup = 0;
+  // Next position where fixup changes.
+  auto next_source_fixup = jump_source_fixups_.lower_bound(0);
+  int next_source_fixup_offset = next_source_fixup->first;
+  int next_source_fixup_value = next_source_fixup->second;
+
+  for (auto jump_edge : jump_edges_) {
+    int jump_source = jump_edge.first;
+    int jump_destination = jump_edge.second;
+    while (jump_source >= next_source_fixup_offset) {
+      position_fixup = next_source_fixup_value;
+      ++next_source_fixup;
+      next_source_fixup_offset = next_source_fixup->first;
+      next_source_fixup_value = next_source_fixup->second;
+    }
+    jump_source += position_fixup;
+
+    FixJump(jump_source, jump_destination);
+  }
+
+  // Mapped jump edges don't need source fixups, as the position already is an
+  // offset in the new bytecode.
+  for (auto jump_edge : jump_edges_mapped_) {
+    int jump_source = jump_edge.first;
+    int jump_destination = jump_edge.second;
+
+    FixJump(jump_source, jump_destination);
+  }
+}
+
+void RegExpBytecodePeephole::FixJump(int jump_source, int jump_destination) {
+  int fixed_jump_destination =
+      jump_destination +
+      (--jump_destination_fixups_.upper_bound(jump_destination))->second;
+  DCHECK_LT(fixed_jump_destination, Length());
+#ifdef DEBUG
+  // TODO(pthier): This check could be better if we track the bytecodes
+  // actually used and check if we jump to one of them.
+  byte jump_bc = optimized_bytecode_buffer_[fixed_jump_destination];
+  DCHECK_GT(jump_bc, 0);
+  DCHECK_LT(jump_bc, kRegExpBytecodeCount);
+#endif
+
+  if (jump_destination != fixed_jump_destination) {
+    OverwriteValue<uint32_t>(jump_source, fixed_jump_destination);
+  }
+}
+
+void RegExpBytecodePeephole::AddSentinelFixups(int pos) {
+  jump_source_fixups_.emplace(pos, 0);
+  jump_destination_fixups_.emplace(pos, 0);
+}
+
+template <typename T>
+void RegExpBytecodePeephole::EmitValue(T value) {
+  DCHECK(optimized_bytecode_buffer_.begin() + pc() ==
+         optimized_bytecode_buffer_.end());
+  byte* value_byte_iter = reinterpret_cast<byte*>(&value);
+  optimized_bytecode_buffer_.insert(optimized_bytecode_buffer_.end(),
+                                    value_byte_iter,
+                                    value_byte_iter + sizeof(T));
+}
+
+template <typename T>
+void RegExpBytecodePeephole::OverwriteValue(int offset, T value) {
+  byte* value_byte_iter = reinterpret_cast<byte*>(&value);
+  byte* value_byte_iter_end = value_byte_iter + sizeof(T);
+  while (value_byte_iter < value_byte_iter_end) {
+    optimized_bytecode_buffer_[offset++] = *value_byte_iter++;
+  }
+}
+
+void RegExpBytecodePeephole::CopyRangeToOutput(const byte* orig_bytecode,
+                                               int start, int length) {
+  DCHECK(optimized_bytecode_buffer_.begin() + pc() ==
+         optimized_bytecode_buffer_.end());
+  optimized_bytecode_buffer_.insert(optimized_bytecode_buffer_.end(),
+                                    orig_bytecode + start,
+                                    orig_bytecode + start + length);
+}
+
+void RegExpBytecodePeephole::SetRange(byte value, int count) {
+  DCHECK(optimized_bytecode_buffer_.begin() + pc() ==
+         optimized_bytecode_buffer_.end());
+  optimized_bytecode_buffer_.insert(optimized_bytecode_buffer_.end(), count,
+                                    value);
+}
+
+void RegExpBytecodePeephole::EmitArgument(int start_pc, const byte* bytecode,
+                                          BytecodeArgumentMapping arg) {
+  int arg_pos = start_pc + arg.offset;
+  switch (arg.length) {
+    case 1:
+      DCHECK_EQ(arg.new_length, arg.length);
+      EmitValue(GetValue<byte>(bytecode, arg_pos));
+      break;
+    case 2:
+      DCHECK_EQ(arg.new_length, arg.length);
+      EmitValue(GetValue<uint16_t>(bytecode, arg_pos));
+      break;
+    case 3: {
+      // Length 3 only occurs in 'packed' arguments where the lowermost byte is
+      // the current bytecode, and the remaining 3 bytes are the packed value.
+      //
+      // We load 4 bytes from position - 1 and shift out the bytecode.
+#ifdef V8_TARGET_BIG_ENDIAN
+      UNIMPLEMENTED();
+      int32_t val = 0;
+#else
+      int32_t val = GetValue<int32_t>(bytecode, arg_pos - 1) >> kBitsPerByte;
+#endif  // V8_TARGET_BIG_ENDIAN
+
+      switch (arg.new_length) {
+        case 2:
+          EmitValue<uint16_t>(val);
+          break;
+        case 3: {
+          // Pack with previously emitted value.
+          auto prev_val =
+              GetValue<int32_t>(&(*optimized_bytecode_buffer_.begin()),
+                                Length() - sizeof(uint32_t));
+#ifdef V8_TARGET_BIG_ENDIAN
+      UNIMPLEMENTED();
+      USE(prev_val);
+#else
+          DCHECK_EQ(prev_val & 0xFFFFFF00, 0);
+          OverwriteValue<uint32_t>(
+              pc() - sizeof(uint32_t),
+              (static_cast<uint32_t>(val) << 8) | (prev_val & 0xFF));
+#endif  // V8_TARGET_BIG_ENDIAN
+          break;
+        }
+        case 4:
+          EmitValue<uint32_t>(val);
+          break;
+      }
+      break;
+    }
+    case 4:
+      DCHECK_EQ(arg.new_length, arg.length);
+      EmitValue(GetValue<uint32_t>(bytecode, arg_pos));
+      break;
+    case 8:
+      DCHECK_EQ(arg.new_length, arg.length);
+      EmitValue(GetValue<uint64_t>(bytecode, arg_pos));
+      break;
+    default:
+      CopyRangeToOutput(bytecode, arg_pos, Min(arg.length, arg.new_length));
+      if (arg.length < arg.new_length) {
+        SetRange(0x00, arg.new_length - arg.length);
+      }
+      break;
+  }
+}
+
+int RegExpBytecodePeephole::pc() const {
+  DCHECK_LE(optimized_bytecode_buffer_.size(), std::numeric_limits<int>::max());
+  return static_cast<int>(optimized_bytecode_buffer_.size());
+}
+
+Zone* RegExpBytecodePeephole::zone() const { return zone_; }
+
+}  // namespace
+
+// static
+Handle<ByteArray> RegExpBytecodePeepholeOptimization::OptimizeBytecode(
+    Isolate* isolate, Zone* zone, Handle<String> source, const byte* bytecode,
+    int length, const ZoneUnorderedMap<int, int>& jump_edges) {
+  RegExpBytecodePeephole peephole(zone, length, jump_edges);
+  bool did_optimize = peephole.OptimizeBytecode(bytecode, length);
+  Handle<ByteArray> array = isolate->factory()->NewByteArray(peephole.Length());
+  peephole.CopyOptimizedBytecode(array->GetDataStartAddress());
+
+  if (did_optimize && FLAG_trace_regexp_peephole_optimization) {
+    PrintF("Original Bytecode:\n");
+    RegExpBytecodeDisassemble(bytecode, length, source->ToCString().get());
+    PrintF("Optimized Bytecode:\n");
+    RegExpBytecodeDisassemble(array->GetDataStartAddress(), peephole.Length(),
+                              source->ToCString().get());
+  }
+
+  return array;
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-bytecode-peephole.h b/js/src/regexp/regexp-bytecode-peephole.h
new file mode 100644
index 0000000000..96349f52cf
--- /dev/null
+++ b/js/src/regexp/regexp-bytecode-peephole.h
@@ -0,0 +1,29 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_BYTECODE_PEEPHOLE_H_
+#define V8_REGEXP_REGEXP_BYTECODE_PEEPHOLE_H_
+
+
+namespace v8 {
+namespace internal {
+
+class ByteArray;
+
+// Peephole optimization for regexp interpreter bytecode.
+// Pre-defined bytecode sequences occuring in the bytecode generated by the
+// RegExpBytecodeGenerator can be optimized into a single bytecode.
+class RegExpBytecodePeepholeOptimization : public AllStatic {
+ public:
+  // Performs peephole optimization on the given bytecode and returns the
+  // optimized bytecode.
+  static Handle<ByteArray> OptimizeBytecode(
+      Isolate* isolate, Zone* zone, Handle<String> source, const byte* bytecode,
+      int length, const ZoneUnorderedMap<int, int>& jump_edges);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_BYTECODE_PEEPHOLE_H_
diff --git a/js/src/regexp/regexp-bytecodes.cc b/js/src/regexp/regexp-bytecodes.cc
new file mode 100644
index 0000000000..ae8f93ac9e
--- /dev/null
+++ b/js/src/regexp/regexp-bytecodes.cc
@@ -0,0 +1,45 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-bytecodes.h"
+
+#include <cctype>
+
+
+namespace v8 {
+namespace internal {
+
+void RegExpBytecodeDisassembleSingle(const byte* code_base, const byte* pc) {
+  PrintF("%s", RegExpBytecodeName(*pc));
+
+  // Args and the bytecode as hex.
+  for (int i = 0; i < RegExpBytecodeLength(*pc); i++) {
+    PrintF(", %02x", pc[i]);
+  }
+  PrintF(" ");
+
+  // Args as ascii.
+  for (int i = 1; i < RegExpBytecodeLength(*pc); i++) {
+    unsigned char b = pc[i];
+    PrintF("%c", std::isprint(b) ? b : '.');
+  }
+  PrintF("\n");
+}
+
+void RegExpBytecodeDisassemble(const byte* code_base, int length,
+                               const char* pattern) {
+  PrintF("[generated bytecode for regexp pattern: '%s']\n", pattern);
+
+  ptrdiff_t offset = 0;
+
+  while (offset < length) {
+    const byte* const pc = code_base + offset;
+    PrintF("%p  %4" V8PRIxPTRDIFF "  ", pc, offset);
+    RegExpBytecodeDisassembleSingle(code_base, pc);
+    offset += RegExpBytecodeLength(*pc);
+  }
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-bytecodes.h b/js/src/regexp/regexp-bytecodes.h
new file mode 100644
index 0000000000..35f7a30dae
--- /dev/null
+++ b/js/src/regexp/regexp-bytecodes.h
@@ -0,0 +1,250 @@
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_BYTECODES_H_
+#define V8_REGEXP_REGEXP_BYTECODES_H_
+
+
+namespace v8 {
+namespace internal {
+
+// Maximum number of bytecodes that will be used (next power of 2 of actually
+// defined bytecodes).
+// All slots between the last actually defined bytecode and maximum id will be
+// filled with BREAKs, indicating an invalid operation. This way using
+// BYTECODE_MASK guarantees no OOB access to the dispatch table.
+constexpr int kRegExpPaddedBytecodeCount = 1 << 6;
+constexpr int BYTECODE_MASK = kRegExpPaddedBytecodeCount - 1;
+// The first argument is packed in with the byte code in one word, but so it
+// has 24 bits, but it can be positive and negative so only use 23 bits for
+// positive values.
+const unsigned int MAX_FIRST_ARG = 0x7fffffu;
+const int BYTECODE_SHIFT = 8;
+STATIC_ASSERT(1 << BYTECODE_SHIFT > BYTECODE_MASK);
+
+// TODO(pthier): Argument offsets of bytecodes should be easily accessible by
+// name or at least by position.
+#define BYTECODE_ITERATOR(V)                                                   \
+  V(BREAK, 0, 4)              /* bc8                                        */ \
+  V(PUSH_CP, 1, 4)            /* bc8 pad24                                  */ \
+  V(PUSH_BT, 2, 8)            /* bc8 pad24 offset32                         */ \
+  V(PUSH_REGISTER, 3, 4)      /* bc8 reg_idx24                              */ \
+  V(SET_REGISTER_TO_CP, 4, 8) /* bc8 reg_idx24 offset32                     */ \
+  V(SET_CP_TO_REGISTER, 5, 4) /* bc8 reg_idx24                              */ \
+  V(SET_REGISTER_TO_SP, 6, 4) /* bc8 reg_idx24                              */ \
+  V(SET_SP_TO_REGISTER, 7, 4) /* bc8 reg_idx24                              */ \
+  V(SET_REGISTER, 8, 8)       /* bc8 reg_idx24 value32                      */ \
+  V(ADVANCE_REGISTER, 9, 8)   /* bc8 reg_idx24 value32                      */ \
+  V(POP_CP, 10, 4)            /* bc8 pad24                                  */ \
+  V(POP_BT, 11, 4)            /* bc8 pad24                                  */ \
+  V(POP_REGISTER, 12, 4)      /* bc8 reg_idx24                              */ \
+  V(FAIL, 13, 4)              /* bc8 pad24                                  */ \
+  V(SUCCEED, 14, 4)           /* bc8 pad24                                  */ \
+  V(ADVANCE_CP, 15, 4)        /* bc8 offset24                               */ \
+  /* Jump to another bytecode given its offset.                             */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x10 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   0x00 (unused) Padding                                   */ \
+  /* 0x20 - 0x3F:   Address of bytecode to jump to                          */ \
+  V(GOTO, 16, 8) /* bc8 pad24 addr32                           */              \
+  /* Check if offset is in range and load character at given offset.        */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x11 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   Offset from current position                            */ \
+  /* 0x20 - 0x3F:   Address of bytecode when load is out of range           */ \
+  V(LOAD_CURRENT_CHAR, 17, 8) /* bc8 offset24 addr32                        */ \
+  /* Load character at given offset without range checks.                   */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x12 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   Offset from current position                            */ \
+  V(LOAD_CURRENT_CHAR_UNCHECKED, 18, 4)    /* bc8 offset24 */                  \
+  V(LOAD_2_CURRENT_CHARS, 19, 8)           /* bc8 offset24 addr32 */           \
+  V(LOAD_2_CURRENT_CHARS_UNCHECKED, 20, 4) /* bc8 offset24 */                  \
+  V(LOAD_4_CURRENT_CHARS, 21, 8)           /* bc8 offset24 addr32 */           \
+  V(LOAD_4_CURRENT_CHARS_UNCHECKED, 22, 4) /* bc8 offset24 */                  \
+  V(CHECK_4_CHARS, 23, 12) /* bc8 pad24 uint32 addr32                    */    \
+  /* Check if current character is equal to a given character               */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x19 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x0F:   0x00 (unused) Padding                                   */ \
+  /* 0x10 - 0x1F:   Character to check                                      */ \
+  /* 0x20 - 0x3F:   Address of bytecode when matched                        */ \
+  V(CHECK_CHAR, 24, 8) /* bc8 pad8 uint16 addr32                     */        \
+  V(CHECK_NOT_4_CHARS, 25, 12) /* bc8 pad24 uint32 addr32 */                   \
+  V(CHECK_NOT_CHAR, 26, 8) /* bc8 pad8 uint16 addr32                     */    \
+  V(AND_CHECK_4_CHARS, 27, 16) /* bc8 pad24 uint32 uint32 addr32 */            \
+  /* Checks if the current character combined with mask (bitwise and)       */ \
+  /* matches a character (e.g. used when two characters in a disjunction    */ \
+  /* differ by only a single bit                                            */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x1c (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x0F:   0x00 (unused) Padding                                   */ \
+  /* 0x10 - 0x1F:   Character to match against (after mask aplied)          */ \
+  /* 0x20 - 0x3F:   Bitmask bitwise and combined with current character     */ \
+  /* 0x40 - 0x5F:   Address of bytecode when matched                        */ \
+  V(AND_CHECK_CHAR, 28, 12)           /* bc8 pad8 uint16 uint32 addr32      */ \
+  V(AND_CHECK_NOT_4_CHARS, 29, 16)    /* bc8 pad24 uint32 uint32 addr32 */     \
+  V(AND_CHECK_NOT_CHAR, 30, 12)       /* bc8 pad8 uint16 uint32 addr32 */      \
+  V(MINUS_AND_CHECK_NOT_CHAR, 31, 12) /* bc8 pad8 uc16 uc16 uc16 addr32 */     \
+  V(CHECK_CHAR_IN_RANGE, 32, 12)      /* bc8 pad24 uc16 uc16 addr32 */         \
+  V(CHECK_CHAR_NOT_IN_RANGE, 33, 12)  /* bc8 pad24 uc16 uc16 addr32 */         \
+  /* Checks if the current character matches any of the characters encoded  */ \
+  /* in a bit table. Similar to/inspired by boyer moore string search       */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x22 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   0x00 (unused) Padding                                   */ \
+  /* 0x20 - 0x3F:   Address of bytecode when bit is set                     */ \
+  /* 0x40 - 0xBF:   Bit table                                               */ \
+  V(CHECK_BIT_IN_TABLE, 34, 24) /* bc8 pad24 addr32 bits128           */       \
+  V(CHECK_LT, 35, 8) /* bc8 pad8 uc16 addr32                       */          \
+  V(CHECK_GT, 36, 8) /* bc8 pad8 uc16 addr32                       */          \
+  V(CHECK_NOT_BACK_REF, 37, 8)         /* bc8 reg_idx24 addr32 */              \
+  V(CHECK_NOT_BACK_REF_NO_CASE, 38, 8) /* bc8 reg_idx24 addr32 */              \
+  V(CHECK_NOT_BACK_REF_NO_CASE_UNICODE, 39, 8)                                 \
+  V(CHECK_NOT_BACK_REF_BACKWARD, 40, 8)         /* bc8 reg_idx24 addr32 */     \
+  V(CHECK_NOT_BACK_REF_NO_CASE_BACKWARD, 41, 8) /* bc8 reg_idx24 addr32 */     \
+  V(CHECK_NOT_BACK_REF_NO_CASE_UNICODE_BACKWARD, 42, 8)                        \
+  V(CHECK_NOT_REGS_EQUAL, 43, 12) /* bc8 regidx24 reg_idx32 addr32 */          \
+  V(CHECK_REGISTER_LT, 44, 12)    /* bc8 reg_idx24 value32 addr32 */           \
+  V(CHECK_REGISTER_GE, 45, 12)    /* bc8 reg_idx24 value32 addr32 */           \
+  V(CHECK_REGISTER_EQ_POS, 46, 8) /* bc8 reg_idx24 addr32 */                   \
+  V(CHECK_AT_START, 47, 8) /* bc8 pad24 addr32                           */    \
+  V(CHECK_NOT_AT_START, 48, 8) /* bc8 offset24 addr32 */                       \
+  /* Checks if the current position matches top of backtrack stack          */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x31 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   0x00 (unused) Padding                                   */ \
+  /* 0x20 - 0x3F:   Address of bytecode when current matches tos            */ \
+  V(CHECK_GREEDY, 49, 8) /* bc8 pad24 addr32                           */      \
+  /* Advance character pointer by given offset and jump to another bytecode.*/ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x32 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   Number of characters to advance                         */ \
+  /* 0x20 - 0x3F:   Address of bytecode to jump to                          */ \
+  V(ADVANCE_CP_AND_GOTO, 50, 8) /* bc8 offset24 addr32                    */   \
+  V(SET_CURRENT_POSITION_FROM_END, 51, 4) /* bc8 idx24 */                      \
+  /* Checks if current position + given offset is in range.                 */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x34 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   Offset from current position                            */ \
+  /* 0x20 - 0x3F:   Address of bytecode when position is out of range       */ \
+  V(CHECK_CURRENT_POSITION, 52, 8) /* bc8 idx24 addr32                     */  \
+  /* Combination of:                                                        */ \
+  /* LOAD_CURRENT_CHAR, CHECK_BIT_IN_TABLE and ADVANCE_CP_AND_GOTO          */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x35 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x3F    Number of characters to advance                         */ \
+  /* 0x40 - 0xBF    Bit Table                                               */ \
+  /* 0xC0 - 0xDF    Address of bytecode when character is matched           */ \
+  /* 0xE0 - 0xFF    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_BIT_IN_TABLE, 53, 32)                                           \
+  /* Combination of:                                                        */ \
+  /* CHECK_CURRENT_POSITION, LOAD_CURRENT_CHAR_UNCHECKED, AND_CHECK_CHAR    */ \
+  /* and ADVANCE_CP_AND_GOTO                                                */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x36 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x2F    Number of characters to advance                         */ \
+  /* 0x30 - 0x3F    Character to match against (after mask applied)         */ \
+  /* 0x40 - 0x5F:   Bitmask bitwise and combined with current character     */ \
+  /* 0x60 - 0x7F    Minimum number of characters this pattern consumes      */ \
+  /* 0x80 - 0x9F    Address of bytecode when character is matched           */ \
+  /* 0xA0 - 0xBF    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_CHAR_AND, 54, 24)                                               \
+  /* Combination of:                                                        */ \
+  /* LOAD_CURRENT_CHAR, CHECK_CHAR and ADVANCE_CP_AND_GOTO                  */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x37 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x2F    Number of characters to advance                         */ \
+  /* 0x30 - 0x3F    Character to match                                      */ \
+  /* 0x40 - 0x5F    Address of bytecode when character is matched           */ \
+  /* 0x60 - 0x7F    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_CHAR, 55, 16)                                                   \
+  /* Combination of:                                                        */ \
+  /* CHECK_CURRENT_POSITION, LOAD_CURRENT_CHAR_UNCHECKED, CHECK_CHAR        */ \
+  /* and ADVANCE_CP_AND_GOTO                                                */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x38 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x2F    Number of characters to advance                         */ \
+  /* 0x30 - 0x3F    Character to match                                      */ \
+  /* 0x40 - 0x5F    Minimum number of characters this pattern consumes      */ \
+  /* 0x60 - 0x7F    Address of bytecode when character is matched           */ \
+  /* 0x80 - 0x9F    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_CHAR_POS_CHECKED, 56, 20)                                       \
+  /* Combination of:                                                        */ \
+  /* LOAD_CURRENT_CHAR, CHECK_CHAR, CHECK_CHAR and ADVANCE_CP_AND_GOTO      */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x39 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x3F    Number of characters to advance                         */ \
+  /* 0x40 - 0x4F    Character to match                                      */ \
+  /* 0x50 - 0x5F    Other Character to match                                */ \
+  /* 0x60 - 0x7F    Address of bytecode when either character is matched    */ \
+  /* 0x80 - 0x9F    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_CHAR_OR_CHAR, 57, 20)                                           \
+  /* Combination of:                                                        */ \
+  /* LOAD_CURRENT_CHAR, CHECK_GT, CHECK_BIT_IN_TABLE, GOTO and              */ \
+  /* and ADVANCE_CP_AND_GOTO                                                */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x3A (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x2F    Number of characters to advance                         */ \
+  /* 0x30 - 0x3F    Character to check if it is less than current char      */ \
+  /* 0x40 - 0xBF    Bit Table                                               */ \
+  /* 0xC0 - 0xDF    Address of bytecode when character is matched           */ \
+  /* 0xE0 - 0xFF    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_GT_OR_NOT_BIT_IN_TABLE, 58, 32)
+
+#define COUNT(...) +1
+static constexpr int kRegExpBytecodeCount = BYTECODE_ITERATOR(COUNT);
+#undef COUNT
+
+// Just making sure we assigned values above properly. They should be
+// contiguous, strictly increasing, and start at 0.
+// TODO(jgruber): Do not explicitly assign values, instead generate them
+// implicitly from the list order.
+STATIC_ASSERT(kRegExpBytecodeCount == 59);
+
+#define DECLARE_BYTECODES(name, code, length) \
+  static constexpr int BC_##name = code;
+BYTECODE_ITERATOR(DECLARE_BYTECODES)
+#undef DECLARE_BYTECODES
+
+static constexpr int kRegExpBytecodeLengths[] = {
+#define DECLARE_BYTECODE_LENGTH(name, code, length) length,
+    BYTECODE_ITERATOR(DECLARE_BYTECODE_LENGTH)
+#undef DECLARE_BYTECODE_LENGTH
+};
+
+inline constexpr int RegExpBytecodeLength(int bytecode) {
+  return kRegExpBytecodeLengths[bytecode];
+}
+
+static const char* const kRegExpBytecodeNames[] = {
+#define DECLARE_BYTECODE_NAME(name, ...) #name,
+    BYTECODE_ITERATOR(DECLARE_BYTECODE_NAME)
+#undef DECLARE_BYTECODE_NAME
+};
+
+inline const char* RegExpBytecodeName(int bytecode) {
+  return kRegExpBytecodeNames[bytecode];
+}
+
+void RegExpBytecodeDisassembleSingle(const byte* code_base, const byte* pc);
+void RegExpBytecodeDisassemble(const byte* code_base, int length,
+                               const char* pattern);
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_BYTECODES_H_
diff --git a/js/src/regexp/regexp-compiler-tonode.cc b/js/src/regexp/regexp-compiler-tonode.cc
new file mode 100644
index 0000000000..fc734ac7c1
--- /dev/null
+++ b/js/src/regexp/regexp-compiler-tonode.cc
@@ -0,0 +1,1675 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-compiler.h"
+
+#include "regexp/regexp.h"
+#ifdef V8_INTL_SUPPORT
+#include "regexp/special-case.h"
+#endif  // V8_INTL_SUPPORT
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/locid.h"
+#include "unicode/uniset.h"
+#include "unicode/utypes.h"
+#endif  // V8_INTL_SUPPORT
+
+namespace v8 {
+namespace internal {
+
+using namespace regexp_compiler_constants;  // NOLINT(build/namespaces)
+
+// -------------------------------------------------------------------
+// Tree to graph conversion
+
+RegExpNode* RegExpAtom::ToNode(RegExpCompiler* compiler,
+                               RegExpNode* on_success) {
+  ZoneList<TextElement>* elms =
+      new (compiler->zone()) ZoneList<TextElement>(1, compiler->zone());
+  elms->Add(TextElement::Atom(this), compiler->zone());
+  return new (compiler->zone())
+      TextNode(elms, compiler->read_backward(), on_success);
+}
+
+RegExpNode* RegExpText::ToNode(RegExpCompiler* compiler,
+                               RegExpNode* on_success) {
+  return new (compiler->zone())
+      TextNode(elements(), compiler->read_backward(), on_success);
+}
+
+static bool CompareInverseRanges(ZoneList<CharacterRange>* ranges,
+                                 const int* special_class, int length) {
+  length--;  // Remove final marker.
+  DCHECK_EQ(kRangeEndMarker, special_class[length]);
+  DCHECK_NE(0, ranges->length());
+  DCHECK_NE(0, length);
+  DCHECK_NE(0, special_class[0]);
+  if (ranges->length() != (length >> 1) + 1) {
+    return false;
+  }
+  CharacterRange range = ranges->at(0);
+  if (range.from() != 0) {
+    return false;
+  }
+  for (int i = 0; i < length; i += 2) {
+    if (special_class[i] != (range.to() + 1)) {
+      return false;
+    }
+    range = ranges->at((i >> 1) + 1);
+    if (special_class[i + 1] != range.from()) {
+      return false;
+    }
+  }
+  if (range.to() != String::kMaxCodePoint) {
+    return false;
+  }
+  return true;
+}
+
+static bool CompareRanges(ZoneList<CharacterRange>* ranges,
+                          const int* special_class, int length) {
+  length--;  // Remove final marker.
+  DCHECK_EQ(kRangeEndMarker, special_class[length]);
+  if (ranges->length() * 2 != length) {
+    return false;
+  }
+  for (int i = 0; i < length; i += 2) {
+    CharacterRange range = ranges->at(i >> 1);
+    if (range.from() != special_class[i] ||
+        range.to() != special_class[i + 1] - 1) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool RegExpCharacterClass::is_standard(Zone* zone) {
+  // TODO(lrn): Remove need for this function, by not throwing away information
+  // along the way.
+  if (is_negated()) {
+    return false;
+  }
+  if (set_.is_standard()) {
+    return true;
+  }
+  if (CompareRanges(set_.ranges(zone), kSpaceRanges, kSpaceRangeCount)) {
+    set_.set_standard_set_type('s');
+    return true;
+  }
+  if (CompareInverseRanges(set_.ranges(zone), kSpaceRanges, kSpaceRangeCount)) {
+    set_.set_standard_set_type('S');
+    return true;
+  }
+  if (CompareInverseRanges(set_.ranges(zone), kLineTerminatorRanges,
+                           kLineTerminatorRangeCount)) {
+    set_.set_standard_set_type('.');
+    return true;
+  }
+  if (CompareRanges(set_.ranges(zone), kLineTerminatorRanges,
+                    kLineTerminatorRangeCount)) {
+    set_.set_standard_set_type('n');
+    return true;
+  }
+  if (CompareRanges(set_.ranges(zone), kWordRanges, kWordRangeCount)) {
+    set_.set_standard_set_type('w');
+    return true;
+  }
+  if (CompareInverseRanges(set_.ranges(zone), kWordRanges, kWordRangeCount)) {
+    set_.set_standard_set_type('W');
+    return true;
+  }
+  return false;
+}
+
+UnicodeRangeSplitter::UnicodeRangeSplitter(ZoneList<CharacterRange>* base) {
+  // The unicode range splitter categorizes given character ranges into:
+  // - Code points from the BMP representable by one code unit.
+  // - Code points outside the BMP that need to be split into surrogate pairs.
+  // - Lone lead surrogates.
+  // - Lone trail surrogates.
+  // Lone surrogates are valid code points, even though no actual characters.
+  // They require special matching to make sure we do not split surrogate pairs.
+
+  for (int i = 0; i < base->length(); i++) AddRange(base->at(i));
+}
+
+void UnicodeRangeSplitter::AddRange(CharacterRange range) {
+  static constexpr uc32 kBmp1Start = 0;
+  static constexpr uc32 kBmp1End = kLeadSurrogateStart - 1;
+  static constexpr uc32 kBmp2Start = kTrailSurrogateEnd + 1;
+  static constexpr uc32 kBmp2End = kNonBmpStart - 1;
+
+  // Ends are all inclusive.
+  STATIC_ASSERT(kBmp1Start == 0);
+  STATIC_ASSERT(kBmp1Start < kBmp1End);
+  STATIC_ASSERT(kBmp1End + 1 == kLeadSurrogateStart);
+  STATIC_ASSERT(kLeadSurrogateStart < kLeadSurrogateEnd);
+  STATIC_ASSERT(kLeadSurrogateEnd + 1 == kTrailSurrogateStart);
+  STATIC_ASSERT(kTrailSurrogateStart < kTrailSurrogateEnd);
+  STATIC_ASSERT(kTrailSurrogateEnd + 1 == kBmp2Start);
+  STATIC_ASSERT(kBmp2Start < kBmp2End);
+  STATIC_ASSERT(kBmp2End + 1 == kNonBmpStart);
+  STATIC_ASSERT(kNonBmpStart < kNonBmpEnd);
+
+  static constexpr uc32 kStarts[] = {
+      kBmp1Start, kLeadSurrogateStart, kTrailSurrogateStart,
+      kBmp2Start, kNonBmpStart,
+  };
+
+  static constexpr uc32 kEnds[] = {
+      kBmp1End, kLeadSurrogateEnd, kTrailSurrogateEnd, kBmp2End, kNonBmpEnd,
+  };
+
+  CharacterRangeVector* const kTargets[] = {
+      &bmp_, &lead_surrogates_, &trail_surrogates_, &bmp_, &non_bmp_,
+  };
+
+  static constexpr int kCount = arraysize(kStarts);
+  STATIC_ASSERT(kCount == arraysize(kEnds));
+  STATIC_ASSERT(kCount == arraysize(kTargets));
+
+  for (int i = 0; i < kCount; i++) {
+    if (kStarts[i] > range.to()) break;
+    const uc32 from = std::max(kStarts[i], range.from());
+    const uc32 to = std::min(kEnds[i], range.to());
+    if (from > to) continue;
+    kTargets[i]->emplace_back(CharacterRange::Range(from, to));
+  }
+}
+
+namespace {
+
+// Translates between new and old V8-isms (SmallVector, ZoneList).
+ZoneList<CharacterRange>* ToCanonicalZoneList(
+    const UnicodeRangeSplitter::CharacterRangeVector* v, Zone* zone) {
+  if (v->empty()) return nullptr;
+
+  ZoneList<CharacterRange>* result =
+      new (zone) ZoneList<CharacterRange>(static_cast<int>(v->size()), zone);
+  for (size_t i = 0; i < v->size(); i++) {
+    result->Add(v->at(i), zone);
+  }
+
+  CharacterRange::Canonicalize(result);
+  return result;
+}
+
+void AddBmpCharacters(RegExpCompiler* compiler, ChoiceNode* result,
+                      RegExpNode* on_success, UnicodeRangeSplitter* splitter) {
+  ZoneList<CharacterRange>* bmp =
+      ToCanonicalZoneList(splitter->bmp(), compiler->zone());
+  if (bmp == nullptr) return;
+  JSRegExp::Flags default_flags = JSRegExp::Flags();
+  result->AddAlternative(GuardedAlternative(TextNode::CreateForCharacterRanges(
+      compiler->zone(), bmp, compiler->read_backward(), on_success,
+      default_flags)));
+}
+
+void AddNonBmpSurrogatePairs(RegExpCompiler* compiler, ChoiceNode* result,
+                             RegExpNode* on_success,
+                             UnicodeRangeSplitter* splitter) {
+  ZoneList<CharacterRange>* non_bmp =
+      ToCanonicalZoneList(splitter->non_bmp(), compiler->zone());
+  if (non_bmp == nullptr) return;
+  DCHECK(!compiler->one_byte());
+  Zone* zone = compiler->zone();
+  JSRegExp::Flags default_flags = JSRegExp::Flags();
+  CharacterRange::Canonicalize(non_bmp);
+  for (int i = 0; i < non_bmp->length(); i++) {
+    // Match surrogate pair.
+    // E.g. [\u10005-\u11005] becomes
+    //      \ud800[\udc05-\udfff]|
+    //      [\ud801-\ud803][\udc00-\udfff]|
+    //      \ud804[\udc00-\udc05]
+    uc32 from = non_bmp->at(i).from();
+    uc32 to = non_bmp->at(i).to();
+    uc16 from_l = unibrow::Utf16::LeadSurrogate(from);
+    uc16 from_t = unibrow::Utf16::TrailSurrogate(from);
+    uc16 to_l = unibrow::Utf16::LeadSurrogate(to);
+    uc16 to_t = unibrow::Utf16::TrailSurrogate(to);
+    if (from_l == to_l) {
+      // The lead surrogate is the same.
+      result->AddAlternative(
+          GuardedAlternative(TextNode::CreateForSurrogatePair(
+              zone, CharacterRange::Singleton(from_l),
+              CharacterRange::Range(from_t, to_t), compiler->read_backward(),
+              on_success, default_flags)));
+    } else {
+      if (from_t != kTrailSurrogateStart) {
+        // Add [from_l][from_t-\udfff]
+        result->AddAlternative(
+            GuardedAlternative(TextNode::CreateForSurrogatePair(
+                zone, CharacterRange::Singleton(from_l),
+                CharacterRange::Range(from_t, kTrailSurrogateEnd),
+                compiler->read_backward(), on_success, default_flags)));
+        from_l++;
+      }
+      if (to_t != kTrailSurrogateEnd) {
+        // Add [to_l][\udc00-to_t]
+        result->AddAlternative(
+            GuardedAlternative(TextNode::CreateForSurrogatePair(
+                zone, CharacterRange::Singleton(to_l),
+                CharacterRange::Range(kTrailSurrogateStart, to_t),
+                compiler->read_backward(), on_success, default_flags)));
+        to_l--;
+      }
+      if (from_l <= to_l) {
+        // Add [from_l-to_l][\udc00-\udfff]
+        result->AddAlternative(
+            GuardedAlternative(TextNode::CreateForSurrogatePair(
+                zone, CharacterRange::Range(from_l, to_l),
+                CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd),
+                compiler->read_backward(), on_success, default_flags)));
+      }
+    }
+  }
+}
+
+RegExpNode* NegativeLookaroundAgainstReadDirectionAndMatch(
+    RegExpCompiler* compiler, ZoneList<CharacterRange>* lookbehind,
+    ZoneList<CharacterRange>* match, RegExpNode* on_success, bool read_backward,
+    JSRegExp::Flags flags) {
+  Zone* zone = compiler->zone();
+  RegExpNode* match_node = TextNode::CreateForCharacterRanges(
+      zone, match, read_backward, on_success, flags);
+  int stack_register = compiler->UnicodeLookaroundStackRegister();
+  int position_register = compiler->UnicodeLookaroundPositionRegister();
+  RegExpLookaround::Builder lookaround(false, match_node, stack_register,
+                                       position_register);
+  RegExpNode* negative_match = TextNode::CreateForCharacterRanges(
+      zone, lookbehind, !read_backward, lookaround.on_match_success(), flags);
+  return lookaround.ForMatch(negative_match);
+}
+
+RegExpNode* MatchAndNegativeLookaroundInReadDirection(
+    RegExpCompiler* compiler, ZoneList<CharacterRange>* match,
+    ZoneList<CharacterRange>* lookahead, RegExpNode* on_success,
+    bool read_backward, JSRegExp::Flags flags) {
+  Zone* zone = compiler->zone();
+  int stack_register = compiler->UnicodeLookaroundStackRegister();
+  int position_register = compiler->UnicodeLookaroundPositionRegister();
+  RegExpLookaround::Builder lookaround(false, on_success, stack_register,
+                                       position_register);
+  RegExpNode* negative_match = TextNode::CreateForCharacterRanges(
+      zone, lookahead, read_backward, lookaround.on_match_success(), flags);
+  return TextNode::CreateForCharacterRanges(
+      zone, match, read_backward, lookaround.ForMatch(negative_match), flags);
+}
+
+void AddLoneLeadSurrogates(RegExpCompiler* compiler, ChoiceNode* result,
+                           RegExpNode* on_success,
+                           UnicodeRangeSplitter* splitter) {
+  JSRegExp::Flags default_flags = JSRegExp::Flags();
+  ZoneList<CharacterRange>* lead_surrogates =
+      ToCanonicalZoneList(splitter->lead_surrogates(), compiler->zone());
+  if (lead_surrogates == nullptr) return;
+  Zone* zone = compiler->zone();
+  // E.g. \ud801 becomes \ud801(?![\udc00-\udfff]).
+  ZoneList<CharacterRange>* trail_surrogates = CharacterRange::List(
+      zone, CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd));
+
+  RegExpNode* match;
+  if (compiler->read_backward()) {
+    // Reading backward. Assert that reading forward, there is no trail
+    // surrogate, and then backward match the lead surrogate.
+    match = NegativeLookaroundAgainstReadDirectionAndMatch(
+        compiler, trail_surrogates, lead_surrogates, on_success, true,
+        default_flags);
+  } else {
+    // Reading forward. Forward match the lead surrogate and assert that
+    // no trail surrogate follows.
+    match = MatchAndNegativeLookaroundInReadDirection(
+        compiler, lead_surrogates, trail_surrogates, on_success, false,
+        default_flags);
+  }
+  result->AddAlternative(GuardedAlternative(match));
+}
+
+void AddLoneTrailSurrogates(RegExpCompiler* compiler, ChoiceNode* result,
+                            RegExpNode* on_success,
+                            UnicodeRangeSplitter* splitter) {
+  JSRegExp::Flags default_flags = JSRegExp::Flags();
+  ZoneList<CharacterRange>* trail_surrogates =
+      ToCanonicalZoneList(splitter->trail_surrogates(), compiler->zone());
+  if (trail_surrogates == nullptr) return;
+  Zone* zone = compiler->zone();
+  // E.g. \udc01 becomes (?<![\ud800-\udbff])\udc01
+  ZoneList<CharacterRange>* lead_surrogates = CharacterRange::List(
+      zone, CharacterRange::Range(kLeadSurrogateStart, kLeadSurrogateEnd));
+
+  RegExpNode* match;
+  if (compiler->read_backward()) {
+    // Reading backward. Backward match the trail surrogate and assert that no
+    // lead surrogate precedes it.
+    match = MatchAndNegativeLookaroundInReadDirection(
+        compiler, trail_surrogates, lead_surrogates, on_success, true,
+        default_flags);
+  } else {
+    // Reading forward. Assert that reading backward, there is no lead
+    // surrogate, and then forward match the trail surrogate.
+    match = NegativeLookaroundAgainstReadDirectionAndMatch(
+        compiler, lead_surrogates, trail_surrogates, on_success, false,
+        default_flags);
+  }
+  result->AddAlternative(GuardedAlternative(match));
+}
+
+RegExpNode* UnanchoredAdvance(RegExpCompiler* compiler,
+                              RegExpNode* on_success) {
+  // This implements ES2015 21.2.5.2.3, AdvanceStringIndex.
+  DCHECK(!compiler->read_backward());
+  Zone* zone = compiler->zone();
+  // Advance any character. If the character happens to be a lead surrogate and
+  // we advanced into the middle of a surrogate pair, it will work out, as
+  // nothing will match from there. We will have to advance again, consuming
+  // the associated trail surrogate.
+  ZoneList<CharacterRange>* range = CharacterRange::List(
+      zone, CharacterRange::Range(0, String::kMaxUtf16CodeUnit));
+  JSRegExp::Flags default_flags = JSRegExp::Flags();
+  return TextNode::CreateForCharacterRanges(zone, range, false, on_success,
+                                            default_flags);
+}
+
+void AddUnicodeCaseEquivalents(ZoneList<CharacterRange>* ranges, Zone* zone) {
+#ifdef V8_INTL_SUPPORT
+  DCHECK(CharacterRange::IsCanonical(ranges));
+
+  // Micro-optimization to avoid passing large ranges to UnicodeSet::closeOver.
+  // See also https://crbug.com/v8/6727.
+  // TODO(jgruber): This only covers the special case of the {0,0x10FFFF} range,
+  // which we use frequently internally. But large ranges can also easily be
+  // created by the user. We might want to have a more general caching mechanism
+  // for such ranges.
+  if (ranges->length() == 1 && ranges->at(0).IsEverything(kNonBmpEnd)) return;
+
+  // Use ICU to compute the case fold closure over the ranges.
+  icu::UnicodeSet set;
+  for (int i = 0; i < ranges->length(); i++) {
+    set.add(ranges->at(i).from(), ranges->at(i).to());
+  }
+  ranges->Clear();
+  set.closeOver(USET_CASE_INSENSITIVE);
+  // Full case mapping map single characters to multiple characters.
+  // Those are represented as strings in the set. Remove them so that
+  // we end up with only simple and common case mappings.
+  set.removeAllStrings();
+  for (int i = 0; i < set.getRangeCount(); i++) {
+    ranges->Add(CharacterRange::Range(set.getRangeStart(i), set.getRangeEnd(i)),
+                zone);
+  }
+  // No errors and everything we collected have been ranges.
+  CharacterRange::Canonicalize(ranges);
+#endif  // V8_INTL_SUPPORT
+}
+
+}  // namespace
+
+RegExpNode* RegExpCharacterClass::ToNode(RegExpCompiler* compiler,
+                                         RegExpNode* on_success) {
+  set_.Canonicalize();
+  Zone* zone = compiler->zone();
+  ZoneList<CharacterRange>* ranges = this->ranges(zone);
+  if (NeedsUnicodeCaseEquivalents(flags_)) {
+    AddUnicodeCaseEquivalents(ranges, zone);
+  }
+  if (IsUnicode(flags_) && !compiler->one_byte() &&
+      !contains_split_surrogate()) {
+    if (is_negated()) {
+      ZoneList<CharacterRange>* negated =
+          new (zone) ZoneList<CharacterRange>(2, zone);
+      CharacterRange::Negate(ranges, negated, zone);
+      ranges = negated;
+    }
+    if (ranges->length() == 0) {
+      JSRegExp::Flags default_flags;
+      RegExpCharacterClass* fail =
+          new (zone) RegExpCharacterClass(zone, ranges, default_flags);
+      return new (zone) TextNode(fail, compiler->read_backward(), on_success);
+    }
+    if (standard_type() == '*') {
+      return UnanchoredAdvance(compiler, on_success);
+    } else {
+      ChoiceNode* result = new (zone) ChoiceNode(2, zone);
+      UnicodeRangeSplitter splitter(ranges);
+      AddBmpCharacters(compiler, result, on_success, &splitter);
+      AddNonBmpSurrogatePairs(compiler, result, on_success, &splitter);
+      AddLoneLeadSurrogates(compiler, result, on_success, &splitter);
+      AddLoneTrailSurrogates(compiler, result, on_success, &splitter);
+      return result;
+    }
+  } else {
+    return new (zone) TextNode(this, compiler->read_backward(), on_success);
+  }
+}
+
+int CompareFirstChar(RegExpTree* const* a, RegExpTree* const* b) {
+  RegExpAtom* atom1 = (*a)->AsAtom();
+  RegExpAtom* atom2 = (*b)->AsAtom();
+  uc16 character1 = atom1->data().at(0);
+  uc16 character2 = atom2->data().at(0);
+  if (character1 < character2) return -1;
+  if (character1 > character2) return 1;
+  return 0;
+}
+
+#ifdef V8_INTL_SUPPORT
+
+// Case Insensitve comparesion
+int CompareFirstCharCaseInsensitve(RegExpTree* const* a, RegExpTree* const* b) {
+  RegExpAtom* atom1 = (*a)->AsAtom();
+  RegExpAtom* atom2 = (*b)->AsAtom();
+  icu::UnicodeString character1(atom1->data().at(0));
+  return character1.caseCompare(atom2->data().at(0), U_FOLD_CASE_DEFAULT);
+}
+
+#else
+
+static unibrow::uchar Canonical(
+    unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
+    unibrow::uchar c) {
+  unibrow::uchar chars[unibrow::Ecma262Canonicalize::kMaxWidth];
+  int length = canonicalize->get(c, '\0', chars);
+  DCHECK_LE(length, 1);
+  unibrow::uchar canonical = c;
+  if (length == 1) canonical = chars[0];
+  return canonical;
+}
+
+int CompareFirstCharCaseIndependent(
+    unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
+    RegExpTree* const* a, RegExpTree* const* b) {
+  RegExpAtom* atom1 = (*a)->AsAtom();
+  RegExpAtom* atom2 = (*b)->AsAtom();
+  unibrow::uchar character1 = atom1->data().at(0);
+  unibrow::uchar character2 = atom2->data().at(0);
+  if (character1 == character2) return 0;
+  if (character1 >= 'a' || character2 >= 'a') {
+    character1 = Canonical(canonicalize, character1);
+    character2 = Canonical(canonicalize, character2);
+  }
+  return static_cast<int>(character1) - static_cast<int>(character2);
+}
+#endif  // V8_INTL_SUPPORT
+
+// We can stable sort runs of atoms, since the order does not matter if they
+// start with different characters.
+// Returns true if any consecutive atoms were found.
+bool RegExpDisjunction::SortConsecutiveAtoms(RegExpCompiler* compiler) {
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  int length = alternatives->length();
+  bool found_consecutive_atoms = false;
+  for (int i = 0; i < length; i++) {
+    while (i < length) {
+      RegExpTree* alternative = alternatives->at(i);
+      if (alternative->IsAtom()) break;
+      i++;
+    }
+    // i is length or it is the index of an atom.
+    if (i == length) break;
+    int first_atom = i;
+    JSRegExp::Flags flags = alternatives->at(i)->AsAtom()->flags();
+    i++;
+    while (i < length) {
+      RegExpTree* alternative = alternatives->at(i);
+      if (!alternative->IsAtom()) break;
+      if (alternative->AsAtom()->flags() != flags) break;
+      i++;
+    }
+    // Sort atoms to get ones with common prefixes together.
+    // This step is more tricky if we are in a case-independent regexp,
+    // because it would change /is|I/ to /I|is/, and order matters when
+    // the regexp parts don't match only disjoint starting points. To fix
+    // this we have a version of CompareFirstChar that uses case-
+    // independent character classes for comparison.
+    DCHECK_LT(first_atom, alternatives->length());
+    DCHECK_LE(i, alternatives->length());
+    DCHECK_LE(first_atom, i);
+    if (IgnoreCase(flags)) {
+#ifdef V8_INTL_SUPPORT
+      alternatives->StableSort(CompareFirstCharCaseInsensitve, first_atom,
+                               i - first_atom);
+#else
+      unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize =
+          compiler->isolate()->regexp_macro_assembler_canonicalize();
+      auto compare_closure = [canonicalize](RegExpTree* const* a,
+                                            RegExpTree* const* b) {
+        return CompareFirstCharCaseIndependent(canonicalize, a, b);
+      };
+      alternatives->StableSort(compare_closure, first_atom, i - first_atom);
+#endif  // V8_INTL_SUPPORT
+    } else {
+      alternatives->StableSort(CompareFirstChar, first_atom, i - first_atom);
+    }
+    if (i - first_atom > 1) found_consecutive_atoms = true;
+  }
+  return found_consecutive_atoms;
+}
+
+// Optimizes ab|ac|az to a(?:b|c|d).
+void RegExpDisjunction::RationalizeConsecutiveAtoms(RegExpCompiler* compiler) {
+  Zone* zone = compiler->zone();
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  int length = alternatives->length();
+
+  int write_posn = 0;
+  int i = 0;
+  while (i < length) {
+    RegExpTree* alternative = alternatives->at(i);
+    if (!alternative->IsAtom()) {
+      alternatives->at(write_posn++) = alternatives->at(i);
+      i++;
+      continue;
+    }
+    RegExpAtom* const atom = alternative->AsAtom();
+    JSRegExp::Flags flags = atom->flags();
+#ifdef V8_INTL_SUPPORT
+    icu::UnicodeString common_prefix(atom->data().at(0));
+#else
+    unibrow::uchar common_prefix = atom->data().at(0);
+#endif  // V8_INTL_SUPPORT
+    int first_with_prefix = i;
+    int prefix_length = atom->length();
+    i++;
+    while (i < length) {
+      alternative = alternatives->at(i);
+      if (!alternative->IsAtom()) break;
+      RegExpAtom* const atom = alternative->AsAtom();
+      if (atom->flags() != flags) break;
+#ifdef V8_INTL_SUPPORT
+      icu::UnicodeString new_prefix(atom->data().at(0));
+      if (new_prefix != common_prefix) {
+        if (!IgnoreCase(flags)) break;
+        if (common_prefix.caseCompare(new_prefix, U_FOLD_CASE_DEFAULT) != 0)
+          break;
+      }
+#else
+      unibrow::uchar new_prefix = atom->data().at(0);
+      if (new_prefix != common_prefix) {
+        if (!IgnoreCase(flags)) break;
+        unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize =
+            compiler->isolate()->regexp_macro_assembler_canonicalize();
+        new_prefix = Canonical(canonicalize, new_prefix);
+        common_prefix = Canonical(canonicalize, common_prefix);
+        if (new_prefix != common_prefix) break;
+      }
+#endif  // V8_INTL_SUPPORT
+      prefix_length = Min(prefix_length, atom->length());
+      i++;
+    }
+    if (i > first_with_prefix + 2) {
+      // Found worthwhile run of alternatives with common prefix of at least one
+      // character.  The sorting function above did not sort on more than one
+      // character for reasons of correctness, but there may still be a longer
+      // common prefix if the terms were similar or presorted in the input.
+      // Find out how long the common prefix is.
+      int run_length = i - first_with_prefix;
+      RegExpAtom* const atom = alternatives->at(first_with_prefix)->AsAtom();
+      for (int j = 1; j < run_length && prefix_length > 1; j++) {
+        RegExpAtom* old_atom =
+            alternatives->at(j + first_with_prefix)->AsAtom();
+        for (int k = 1; k < prefix_length; k++) {
+          if (atom->data().at(k) != old_atom->data().at(k)) {
+            prefix_length = k;
+            break;
+          }
+        }
+      }
+      RegExpAtom* prefix = new (zone)
+          RegExpAtom(atom->data().SubVector(0, prefix_length), flags);
+      ZoneList<RegExpTree*>* pair = new (zone) ZoneList<RegExpTree*>(2, zone);
+      pair->Add(prefix, zone);
+      ZoneList<RegExpTree*>* suffixes =
+          new (zone) ZoneList<RegExpTree*>(run_length, zone);
+      for (int j = 0; j < run_length; j++) {
+        RegExpAtom* old_atom =
+            alternatives->at(j + first_with_prefix)->AsAtom();
+        int len = old_atom->length();
+        if (len == prefix_length) {
+          suffixes->Add(new (zone) RegExpEmpty(), zone);
+        } else {
+          RegExpTree* suffix = new (zone) RegExpAtom(
+              old_atom->data().SubVector(prefix_length, old_atom->length()),
+              flags);
+          suffixes->Add(suffix, zone);
+        }
+      }
+      pair->Add(new (zone) RegExpDisjunction(suffixes), zone);
+      alternatives->at(write_posn++) = new (zone) RegExpAlternative(pair);
+    } else {
+      // Just copy any non-worthwhile alternatives.
+      for (int j = first_with_prefix; j < i; j++) {
+        alternatives->at(write_posn++) = alternatives->at(j);
+      }
+    }
+  }
+  alternatives->Rewind(write_posn);  // Trim end of array.
+}
+
+// Optimizes b|c|z to [bcz].
+void RegExpDisjunction::FixSingleCharacterDisjunctions(
+    RegExpCompiler* compiler) {
+  Zone* zone = compiler->zone();
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  int length = alternatives->length();
+
+  int write_posn = 0;
+  int i = 0;
+  while (i < length) {
+    RegExpTree* alternative = alternatives->at(i);
+    if (!alternative->IsAtom()) {
+      alternatives->at(write_posn++) = alternatives->at(i);
+      i++;
+      continue;
+    }
+    RegExpAtom* const atom = alternative->AsAtom();
+    if (atom->length() != 1) {
+      alternatives->at(write_posn++) = alternatives->at(i);
+      i++;
+      continue;
+    }
+    JSRegExp::Flags flags = atom->flags();
+    DCHECK_IMPLIES(IsUnicode(flags),
+                   !unibrow::Utf16::IsLeadSurrogate(atom->data().at(0)));
+    bool contains_trail_surrogate =
+        unibrow::Utf16::IsTrailSurrogate(atom->data().at(0));
+    int first_in_run = i;
+    i++;
+    // Find a run of single-character atom alternatives that have identical
+    // flags (case independence and unicode-ness).
+    while (i < length) {
+      alternative = alternatives->at(i);
+      if (!alternative->IsAtom()) break;
+      RegExpAtom* const atom = alternative->AsAtom();
+      if (atom->length() != 1) break;
+      if (atom->flags() != flags) break;
+      DCHECK_IMPLIES(IsUnicode(flags),
+                     !unibrow::Utf16::IsLeadSurrogate(atom->data().at(0)));
+      contains_trail_surrogate |=
+          unibrow::Utf16::IsTrailSurrogate(atom->data().at(0));
+      i++;
+    }
+    if (i > first_in_run + 1) {
+      // Found non-trivial run of single-character alternatives.
+      int run_length = i - first_in_run;
+      ZoneList<CharacterRange>* ranges =
+          new (zone) ZoneList<CharacterRange>(2, zone);
+      for (int j = 0; j < run_length; j++) {
+        RegExpAtom* old_atom = alternatives->at(j + first_in_run)->AsAtom();
+        DCHECK_EQ(old_atom->length(), 1);
+        ranges->Add(CharacterRange::Singleton(old_atom->data().at(0)), zone);
+      }
+      RegExpCharacterClass::CharacterClassFlags character_class_flags;
+      if (IsUnicode(flags) && contains_trail_surrogate) {
+        character_class_flags = RegExpCharacterClass::CONTAINS_SPLIT_SURROGATE;
+      }
+      alternatives->at(write_posn++) = new (zone)
+          RegExpCharacterClass(zone, ranges, flags, character_class_flags);
+    } else {
+      // Just copy any trivial alternatives.
+      for (int j = first_in_run; j < i; j++) {
+        alternatives->at(write_posn++) = alternatives->at(j);
+      }
+    }
+  }
+  alternatives->Rewind(write_posn);  // Trim end of array.
+}
+
+RegExpNode* RegExpDisjunction::ToNode(RegExpCompiler* compiler,
+                                      RegExpNode* on_success) {
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+
+  if (alternatives->length() > 2) {
+    bool found_consecutive_atoms = SortConsecutiveAtoms(compiler);
+    if (found_consecutive_atoms) RationalizeConsecutiveAtoms(compiler);
+    FixSingleCharacterDisjunctions(compiler);
+    if (alternatives->length() == 1) {
+      return alternatives->at(0)->ToNode(compiler, on_success);
+    }
+  }
+
+  int length = alternatives->length();
+
+  ChoiceNode* result =
+      new (compiler->zone()) ChoiceNode(length, compiler->zone());
+  for (int i = 0; i < length; i++) {
+    GuardedAlternative alternative(
+        alternatives->at(i)->ToNode(compiler, on_success));
+    result->AddAlternative(alternative);
+  }
+  return result;
+}
+
+RegExpNode* RegExpQuantifier::ToNode(RegExpCompiler* compiler,
+                                     RegExpNode* on_success) {
+  return ToNode(min(), max(), is_greedy(), body(), compiler, on_success);
+}
+
+namespace {
+// Desugar \b to (?<=\w)(?=\W)|(?<=\W)(?=\w) and
+//         \B to (?<=\w)(?=\w)|(?<=\W)(?=\W)
+RegExpNode* BoundaryAssertionAsLookaround(RegExpCompiler* compiler,
+                                          RegExpNode* on_success,
+                                          RegExpAssertion::AssertionType type,
+                                          JSRegExp::Flags flags) {
+  DCHECK(NeedsUnicodeCaseEquivalents(flags));
+  Zone* zone = compiler->zone();
+  ZoneList<CharacterRange>* word_range =
+      new (zone) ZoneList<CharacterRange>(2, zone);
+  CharacterRange::AddClassEscape('w', word_range, true, zone);
+  int stack_register = compiler->UnicodeLookaroundStackRegister();
+  int position_register = compiler->UnicodeLookaroundPositionRegister();
+  ChoiceNode* result = new (zone) ChoiceNode(2, zone);
+  // Add two choices. The (non-)boundary could start with a word or
+  // a non-word-character.
+  for (int i = 0; i < 2; i++) {
+    bool lookbehind_for_word = i == 0;
+    bool lookahead_for_word =
+        (type == RegExpAssertion::BOUNDARY) ^ lookbehind_for_word;
+    // Look to the left.
+    RegExpLookaround::Builder lookbehind(lookbehind_for_word, on_success,
+                                         stack_register, position_register);
+    RegExpNode* backward = TextNode::CreateForCharacterRanges(
+        zone, word_range, true, lookbehind.on_match_success(), flags);
+    // Look to the right.
+    RegExpLookaround::Builder lookahead(lookahead_for_word,
+                                        lookbehind.ForMatch(backward),
+                                        stack_register, position_register);
+    RegExpNode* forward = TextNode::CreateForCharacterRanges(
+        zone, word_range, false, lookahead.on_match_success(), flags);
+    result->AddAlternative(GuardedAlternative(lookahead.ForMatch(forward)));
+  }
+  return result;
+}
+}  // anonymous namespace
+
+RegExpNode* RegExpAssertion::ToNode(RegExpCompiler* compiler,
+                                    RegExpNode* on_success) {
+  NodeInfo info;
+  Zone* zone = compiler->zone();
+
+  switch (assertion_type()) {
+    case START_OF_LINE:
+      return AssertionNode::AfterNewline(on_success);
+    case START_OF_INPUT:
+      return AssertionNode::AtStart(on_success);
+    case BOUNDARY:
+      return NeedsUnicodeCaseEquivalents(flags_)
+                 ? BoundaryAssertionAsLookaround(compiler, on_success, BOUNDARY,
+                                                 flags_)
+                 : AssertionNode::AtBoundary(on_success);
+    case NON_BOUNDARY:
+      return NeedsUnicodeCaseEquivalents(flags_)
+                 ? BoundaryAssertionAsLookaround(compiler, on_success,
+                                                 NON_BOUNDARY, flags_)
+                 : AssertionNode::AtNonBoundary(on_success);
+    case END_OF_INPUT:
+      return AssertionNode::AtEnd(on_success);
+    case END_OF_LINE: {
+      // Compile $ in multiline regexps as an alternation with a positive
+      // lookahead in one side and an end-of-input on the other side.
+      // We need two registers for the lookahead.
+      int stack_pointer_register = compiler->AllocateRegister();
+      int position_register = compiler->AllocateRegister();
+      // The ChoiceNode to distinguish between a newline and end-of-input.
+      ChoiceNode* result = new (zone) ChoiceNode(2, zone);
+      // Create a newline atom.
+      ZoneList<CharacterRange>* newline_ranges =
+          new (zone) ZoneList<CharacterRange>(3, zone);
+      CharacterRange::AddClassEscape('n', newline_ranges, false, zone);
+      JSRegExp::Flags default_flags = JSRegExp::Flags();
+      RegExpCharacterClass* newline_atom =
+          new (zone) RegExpCharacterClass('n', default_flags);
+      TextNode* newline_matcher =
+          new (zone) TextNode(newline_atom, false,
+                              ActionNode::PositiveSubmatchSuccess(
+                                  stack_pointer_register, position_register,
+                                  0,   // No captures inside.
+                                  -1,  // Ignored if no captures.
+                                  on_success));
+      // Create an end-of-input matcher.
+      RegExpNode* end_of_line = ActionNode::BeginSubmatch(
+          stack_pointer_register, position_register, newline_matcher);
+      // Add the two alternatives to the ChoiceNode.
+      GuardedAlternative eol_alternative(end_of_line);
+      result->AddAlternative(eol_alternative);
+      GuardedAlternative end_alternative(AssertionNode::AtEnd(on_success));
+      result->AddAlternative(end_alternative);
+      return result;
+    }
+    default:
+      UNREACHABLE();
+  }
+  return on_success;
+}
+
+RegExpNode* RegExpBackReference::ToNode(RegExpCompiler* compiler,
+                                        RegExpNode* on_success) {
+  return new (compiler->zone())
+      BackReferenceNode(RegExpCapture::StartRegister(index()),
+                        RegExpCapture::EndRegister(index()), flags_,
+                        compiler->read_backward(), on_success);
+}
+
+RegExpNode* RegExpEmpty::ToNode(RegExpCompiler* compiler,
+                                RegExpNode* on_success) {
+  return on_success;
+}
+
+RegExpLookaround::Builder::Builder(bool is_positive, RegExpNode* on_success,
+                                   int stack_pointer_register,
+                                   int position_register,
+                                   int capture_register_count,
+                                   int capture_register_start)
+    : is_positive_(is_positive),
+      on_success_(on_success),
+      stack_pointer_register_(stack_pointer_register),
+      position_register_(position_register) {
+  if (is_positive_) {
+    on_match_success_ = ActionNode::PositiveSubmatchSuccess(
+        stack_pointer_register, position_register, capture_register_count,
+        capture_register_start, on_success_);
+  } else {
+    Zone* zone = on_success_->zone();
+    on_match_success_ = new (zone) NegativeSubmatchSuccess(
+        stack_pointer_register, position_register, capture_register_count,
+        capture_register_start, zone);
+  }
+}
+
+RegExpNode* RegExpLookaround::Builder::ForMatch(RegExpNode* match) {
+  if (is_positive_) {
+    return ActionNode::BeginSubmatch(stack_pointer_register_,
+                                     position_register_, match);
+  } else {
+    Zone* zone = on_success_->zone();
+    // We use a ChoiceNode to represent the negative lookaround. The first
+    // alternative is the negative match. On success, the end node backtracks.
+    // On failure, the second alternative is tried and leads to success.
+    // NegativeLookaheadChoiceNode is a special ChoiceNode that ignores the
+    // first exit when calculating quick checks.
+    ChoiceNode* choice_node = new (zone) NegativeLookaroundChoiceNode(
+        GuardedAlternative(match), GuardedAlternative(on_success_), zone);
+    return ActionNode::BeginSubmatch(stack_pointer_register_,
+                                     position_register_, choice_node);
+  }
+}
+
+RegExpNode* RegExpLookaround::ToNode(RegExpCompiler* compiler,
+                                     RegExpNode* on_success) {
+  int stack_pointer_register = compiler->AllocateRegister();
+  int position_register = compiler->AllocateRegister();
+
+  const int registers_per_capture = 2;
+  const int register_of_first_capture = 2;
+  int register_count = capture_count_ * registers_per_capture;
+  int register_start =
+      register_of_first_capture + capture_from_ * registers_per_capture;
+
+  RegExpNode* result;
+  bool was_reading_backward = compiler->read_backward();
+  compiler->set_read_backward(type() == LOOKBEHIND);
+  Builder builder(is_positive(), on_success, stack_pointer_register,
+                  position_register, register_count, register_start);
+  RegExpNode* match = body_->ToNode(compiler, builder.on_match_success());
+  result = builder.ForMatch(match);
+  compiler->set_read_backward(was_reading_backward);
+  return result;
+}
+
+RegExpNode* RegExpCapture::ToNode(RegExpCompiler* compiler,
+                                  RegExpNode* on_success) {
+  return ToNode(body(), index(), compiler, on_success);
+}
+
+RegExpNode* RegExpCapture::ToNode(RegExpTree* body, int index,
+                                  RegExpCompiler* compiler,
+                                  RegExpNode* on_success) {
+  DCHECK_NOT_NULL(body);
+  int start_reg = RegExpCapture::StartRegister(index);
+  int end_reg = RegExpCapture::EndRegister(index);
+  if (compiler->read_backward()) std::swap(start_reg, end_reg);
+  RegExpNode* store_end = ActionNode::StorePosition(end_reg, true, on_success);
+  RegExpNode* body_node = body->ToNode(compiler, store_end);
+  return ActionNode::StorePosition(start_reg, true, body_node);
+}
+
+namespace {
+
+class AssertionSequenceRewriter final {
+ public:
+  // TODO(jgruber): Consider moving this to a separate AST tree rewriter pass
+  // instead of sprinkling rewrites into the AST->Node conversion process.
+  static void MaybeRewrite(ZoneList<RegExpTree*>* terms, Zone* zone) {
+    AssertionSequenceRewriter rewriter(terms, zone);
+
+    static constexpr int kNoIndex = -1;
+    int from = kNoIndex;
+
+    for (int i = 0; i < terms->length(); i++) {
+      RegExpTree* t = terms->at(i);
+      if (from == kNoIndex && t->IsAssertion()) {
+        from = i;  // Start a sequence.
+      } else if (from != kNoIndex && !t->IsAssertion()) {
+        // Terminate and process the sequence.
+        if (i - from > 1) rewriter.Rewrite(from, i);
+        from = kNoIndex;
+      }
+    }
+
+    if (from != kNoIndex && terms->length() - from > 1) {
+      rewriter.Rewrite(from, terms->length());
+    }
+  }
+
+  // All assertions are zero width. A consecutive sequence of assertions is
+  // order-independent. There's two ways we can optimize here:
+  // 1. fold all identical assertions.
+  // 2. if any assertion combinations are known to fail (e.g. \b\B), the entire
+  //    sequence fails.
+  void Rewrite(int from, int to) {
+    DCHECK_GT(to, from + 1);
+
+    // Bitfield of all seen assertions.
+    uint32_t seen_assertions = 0;
+    STATIC_ASSERT(RegExpAssertion::LAST_TYPE < kUInt32Size * kBitsPerByte);
+
+    // Flags must match for folding.
+    JSRegExp::Flags flags = terms_->at(from)->AsAssertion()->flags();
+    bool saw_mismatched_flags = false;
+
+    for (int i = from; i < to; i++) {
+      RegExpAssertion* t = terms_->at(i)->AsAssertion();
+      if (t->flags() != flags) saw_mismatched_flags = true;
+      const uint32_t bit = 1 << t->assertion_type();
+
+      if ((seen_assertions & bit) && !saw_mismatched_flags) {
+        // Fold duplicates.
+        terms_->Set(i, new (zone_) RegExpEmpty());
+      }
+
+      seen_assertions |= bit;
+    }
+
+    // Collapse failures.
+    const uint32_t always_fails_mask =
+        1 << RegExpAssertion::BOUNDARY | 1 << RegExpAssertion::NON_BOUNDARY;
+    if ((seen_assertions & always_fails_mask) == always_fails_mask) {
+      ReplaceSequenceWithFailure(from, to);
+    }
+  }
+
+  void ReplaceSequenceWithFailure(int from, int to) {
+    // Replace the entire sequence with a single node that always fails.
+    // TODO(jgruber): Consider adding an explicit Fail kind. Until then, the
+    // negated '*' (everything) range serves the purpose.
+    ZoneList<CharacterRange>* ranges =
+        new (zone_) ZoneList<CharacterRange>(0, zone_);
+    RegExpCharacterClass* cc =
+        new (zone_) RegExpCharacterClass(zone_, ranges, JSRegExp::Flags());
+    terms_->Set(from, cc);
+
+    // Zero out the rest.
+    RegExpEmpty* empty = new (zone_) RegExpEmpty();
+    for (int i = from + 1; i < to; i++) terms_->Set(i, empty);
+  }
+
+ private:
+  AssertionSequenceRewriter(ZoneList<RegExpTree*>* terms, Zone* zone)
+      : zone_(zone), terms_(terms) {}
+
+  Zone* zone_;
+  ZoneList<RegExpTree*>* terms_;
+};
+
+}  // namespace
+
+RegExpNode* RegExpAlternative::ToNode(RegExpCompiler* compiler,
+                                      RegExpNode* on_success) {
+  ZoneList<RegExpTree*>* children = nodes();
+
+  AssertionSequenceRewriter::MaybeRewrite(children, compiler->zone());
+
+  RegExpNode* current = on_success;
+  if (compiler->read_backward()) {
+    for (int i = 0; i < children->length(); i++) {
+      current = children->at(i)->ToNode(compiler, current);
+    }
+  } else {
+    for (int i = children->length() - 1; i >= 0; i--) {
+      current = children->at(i)->ToNode(compiler, current);
+    }
+  }
+  return current;
+}
+
+static void AddClass(const int* elmv, int elmc,
+                     ZoneList<CharacterRange>* ranges, Zone* zone) {
+  elmc--;
+  DCHECK_EQ(kRangeEndMarker, elmv[elmc]);
+  for (int i = 0; i < elmc; i += 2) {
+    DCHECK(elmv[i] < elmv[i + 1]);
+    ranges->Add(CharacterRange::Range(elmv[i], elmv[i + 1] - 1), zone);
+  }
+}
+
+static void AddClassNegated(const int* elmv, int elmc,
+                            ZoneList<CharacterRange>* ranges, Zone* zone) {
+  elmc--;
+  DCHECK_EQ(kRangeEndMarker, elmv[elmc]);
+  DCHECK_NE(0x0000, elmv[0]);
+  DCHECK_NE(String::kMaxCodePoint, elmv[elmc - 1]);
+  uc16 last = 0x0000;
+  for (int i = 0; i < elmc; i += 2) {
+    DCHECK(last <= elmv[i] - 1);
+    DCHECK(elmv[i] < elmv[i + 1]);
+    ranges->Add(CharacterRange::Range(last, elmv[i] - 1), zone);
+    last = elmv[i + 1];
+  }
+  ranges->Add(CharacterRange::Range(last, String::kMaxCodePoint), zone);
+}
+
+void CharacterRange::AddClassEscape(char type, ZoneList<CharacterRange>* ranges,
+                                    bool add_unicode_case_equivalents,
+                                    Zone* zone) {
+  if (add_unicode_case_equivalents && (type == 'w' || type == 'W')) {
+    // See #sec-runtime-semantics-wordcharacters-abstract-operation
+    // In case of unicode and ignore_case, we need to create the closure over
+    // case equivalent characters before negating.
+    ZoneList<CharacterRange>* new_ranges =
+        new (zone) ZoneList<CharacterRange>(2, zone);
+    AddClass(kWordRanges, kWordRangeCount, new_ranges, zone);
+    AddUnicodeCaseEquivalents(new_ranges, zone);
+    if (type == 'W') {
+      ZoneList<CharacterRange>* negated =
+          new (zone) ZoneList<CharacterRange>(2, zone);
+      CharacterRange::Negate(new_ranges, negated, zone);
+      new_ranges = negated;
+    }
+    ranges->AddAll(*new_ranges, zone);
+    return;
+  }
+  AddClassEscape(type, ranges, zone);
+}
+
+void CharacterRange::AddClassEscape(char type, ZoneList<CharacterRange>* ranges,
+                                    Zone* zone) {
+  switch (type) {
+    case 's':
+      AddClass(kSpaceRanges, kSpaceRangeCount, ranges, zone);
+      break;
+    case 'S':
+      AddClassNegated(kSpaceRanges, kSpaceRangeCount, ranges, zone);
+      break;
+    case 'w':
+      AddClass(kWordRanges, kWordRangeCount, ranges, zone);
+      break;
+    case 'W':
+      AddClassNegated(kWordRanges, kWordRangeCount, ranges, zone);
+      break;
+    case 'd':
+      AddClass(kDigitRanges, kDigitRangeCount, ranges, zone);
+      break;
+    case 'D':
+      AddClassNegated(kDigitRanges, kDigitRangeCount, ranges, zone);
+      break;
+    case '.':
+      AddClassNegated(kLineTerminatorRanges, kLineTerminatorRangeCount, ranges,
+                      zone);
+      break;
+    // This is not a character range as defined by the spec but a
+    // convenient shorthand for a character class that matches any
+    // character.
+    case '*':
+      ranges->Add(CharacterRange::Everything(), zone);
+      break;
+    // This is the set of characters matched by the $ and ^ symbols
+    // in multiline mode.
+    case 'n':
+      AddClass(kLineTerminatorRanges, kLineTerminatorRangeCount, ranges, zone);
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+Vector<const int> CharacterRange::GetWordBounds() {
+  return Vector<const int>(kWordRanges, kWordRangeCount - 1);
+}
+
+#ifdef V8_INTL_SUPPORT
+struct IgnoreSet {
+  IgnoreSet() : set(BuildIgnoreSet()) {}
+  const icu::UnicodeSet set;
+};
+
+struct SpecialAddSet {
+  SpecialAddSet() : set(BuildSpecialAddSet()) {}
+  const icu::UnicodeSet set;
+};
+
+icu::UnicodeSet BuildAsciiAToZSet() {
+  icu::UnicodeSet set('a', 'z');
+  set.add('A', 'Z');
+  set.freeze();
+  return set;
+}
+
+struct AsciiAToZSet {
+  AsciiAToZSet() : set(BuildAsciiAToZSet()) {}
+  const icu::UnicodeSet set;
+};
+
+static base::LazyInstance<IgnoreSet>::type ignore_set =
+    LAZY_INSTANCE_INITIALIZER;
+
+static base::LazyInstance<SpecialAddSet>::type special_add_set =
+    LAZY_INSTANCE_INITIALIZER;
+
+static base::LazyInstance<AsciiAToZSet>::type ascii_a_to_z_set =
+    LAZY_INSTANCE_INITIALIZER;
+#endif  // V8_INTL_SUPPORT
+
+// static
+void CharacterRange::AddCaseEquivalents(Isolate* isolate, Zone* zone,
+                                        ZoneList<CharacterRange>* ranges,
+                                        bool is_one_byte) {
+  CharacterRange::Canonicalize(ranges);
+  int range_count = ranges->length();
+#ifdef V8_INTL_SUPPORT
+  icu::UnicodeSet others;
+  for (int i = 0; i < range_count; i++) {
+    CharacterRange range = ranges->at(i);
+    uc32 from = range.from();
+    if (from > String::kMaxUtf16CodeUnit) continue;
+    uc32 to = Min(range.to(), String::kMaxUtf16CodeUnit);
+    // Nothing to be done for surrogates.
+    if (from >= kLeadSurrogateStart && to <= kTrailSurrogateEnd) continue;
+    if (is_one_byte && !RangeContainsLatin1Equivalents(range)) {
+      if (from > String::kMaxOneByteCharCode) continue;
+      if (to > String::kMaxOneByteCharCode) to = String::kMaxOneByteCharCode;
+    }
+    others.add(from, to);
+  }
+
+  // Set of characters already added to ranges that do not need to be added
+  // again.
+  icu::UnicodeSet already_added(others);
+
+  // Set of characters in ranges that are in the 52 ASCII characters [a-zA-Z].
+  icu::UnicodeSet in_ascii_a_to_z(others);
+  in_ascii_a_to_z.retainAll(ascii_a_to_z_set.Pointer()->set);
+
+  // Remove all chars in [a-zA-Z] from others.
+  others.removeAll(in_ascii_a_to_z);
+
+  // Set of characters in ranges that are overlapping with special add set.
+  icu::UnicodeSet in_special_add(others);
+  in_special_add.retainAll(special_add_set.Pointer()->set);
+
+  others.removeAll(in_special_add);
+
+  // Ignore all chars in ignore set.
+  others.removeAll(ignore_set.Pointer()->set);
+
+  // For most of the chars in ranges that is still in others, find the case
+  // equivlant set by calling closeOver(USET_CASE_INSENSITIVE).
+  others.closeOver(USET_CASE_INSENSITIVE);
+
+  // Because closeOver(USET_CASE_INSENSITIVE) may add ASCII [a-zA-Z] to others,
+  // but ECMA262 "i" mode won't consider that, remove them from others.
+  // Ex: U+017F add 'S' and 's' to others.
+  others.removeAll(ascii_a_to_z_set.Pointer()->set);
+
+  // Special handling for in_ascii_a_to_z.
+  for (int32_t i = 0; i < in_ascii_a_to_z.getRangeCount(); i++) {
+    UChar32 start = in_ascii_a_to_z.getRangeStart(i);
+    UChar32 end = in_ascii_a_to_z.getRangeEnd(i);
+    // Check if it is uppercase A-Z by checking bit 6.
+    if (start & 0x0020) {
+      // Add the lowercases
+      others.add(start & 0x005F, end & 0x005F);
+    } else {
+      // Add the uppercases
+      others.add(start | 0x0020, end | 0x0020);
+    }
+  }
+
+  // Special handling for chars in "Special Add" set.
+  for (int32_t i = 0; i < in_special_add.getRangeCount(); i++) {
+    UChar32 end = in_special_add.getRangeEnd(i);
+    for (UChar32 ch = in_special_add.getRangeStart(i); ch <= end; ch++) {
+      // Add the uppercase of this character if itself is not an uppercase
+      // character.
+      // Note: The if condiction cannot be u_islower(ch) because ch could be
+      // neither uppercase nor lowercase but Mn.
+      if (!u_isupper(ch)) {
+        others.add(u_toupper(ch));
+      }
+      icu::UnicodeSet candidates(ch, ch);
+      candidates.closeOver(USET_CASE_INSENSITIVE);
+      for (int32_t j = 0; j < candidates.getRangeCount(); j++) {
+        UChar32 end2 = candidates.getRangeEnd(j);
+        for (UChar32 ch2 = candidates.getRangeStart(j); ch2 <= end2; ch2++) {
+          // Add character that is not uppercase to others.
+          if (!u_isupper(ch2)) {
+            others.add(ch2);
+          }
+        }
+      }
+    }
+  }
+
+  // Remove all characters which already in the ranges.
+  others.removeAll(already_added);
+
+  // Add others to the ranges
+  for (int32_t i = 0; i < others.getRangeCount(); i++) {
+    UChar32 from = others.getRangeStart(i);
+    UChar32 to = others.getRangeEnd(i);
+    if (from == to) {
+      ranges->Add(CharacterRange::Singleton(from), zone);
+    } else {
+      ranges->Add(CharacterRange::Range(from, to), zone);
+    }
+  }
+#else
+  for (int i = 0; i < range_count; i++) {
+    CharacterRange range = ranges->at(i);
+    uc32 bottom = range.from();
+    if (bottom > String::kMaxUtf16CodeUnit) continue;
+    uc32 top = Min(range.to(), String::kMaxUtf16CodeUnit);
+    // Nothing to be done for surrogates.
+    if (bottom >= kLeadSurrogateStart && top <= kTrailSurrogateEnd) continue;
+    if (is_one_byte && !RangeContainsLatin1Equivalents(range)) {
+      if (bottom > String::kMaxOneByteCharCode) continue;
+      if (top > String::kMaxOneByteCharCode) top = String::kMaxOneByteCharCode;
+    }
+    unibrow::uchar chars[unibrow::Ecma262UnCanonicalize::kMaxWidth];
+    if (top == bottom) {
+      // If this is a singleton we just expand the one character.
+      int length = isolate->jsregexp_uncanonicalize()->get(bottom, '\0', chars);
+      for (int i = 0; i < length; i++) {
+        uc32 chr = chars[i];
+        if (chr != bottom) {
+          ranges->Add(CharacterRange::Singleton(chars[i]), zone);
+        }
+      }
+    } else {
+      // If this is a range we expand the characters block by block, expanding
+      // contiguous subranges (blocks) one at a time.  The approach is as
+      // follows.  For a given start character we look up the remainder of the
+      // block that contains it (represented by the end point), for instance we
+      // find 'z' if the character is 'c'.  A block is characterized by the
+      // property that all characters uncanonicalize in the same way, except
+      // that each entry in the result is incremented by the distance from the
+      // first element.  So a-z is a block because 'a' uncanonicalizes to ['a',
+      // 'A'] and the k'th letter uncanonicalizes to ['a' + k, 'A' + k].  Once
+      // we've found the end point we look up its uncanonicalization and
+      // produce a range for each element.  For instance for [c-f] we look up
+      // ['z', 'Z'] and produce [c-f] and [C-F].  We then only add a range if
+      // it is not already contained in the input, so [c-f] will be skipped but
+      // [C-F] will be added.  If this range is not completely contained in a
+      // block we do this for all the blocks covered by the range (handling
+      // characters that is not in a block as a "singleton block").
+      unibrow::uchar equivalents[unibrow::Ecma262UnCanonicalize::kMaxWidth];
+      int pos = bottom;
+      while (pos <= top) {
+        int length =
+            isolate->jsregexp_canonrange()->get(pos, '\0', equivalents);
+        uc32 block_end;
+        if (length == 0) {
+          block_end = pos;
+        } else {
+          DCHECK_EQ(1, length);
+          block_end = equivalents[0];
+        }
+        int end = (block_end > top) ? top : block_end;
+        length = isolate->jsregexp_uncanonicalize()->get(block_end, '\0',
+                                                         equivalents);
+        for (int i = 0; i < length; i++) {
+          uc32 c = equivalents[i];
+          uc32 range_from = c - (block_end - pos);
+          uc32 range_to = c - (block_end - end);
+          if (!(bottom <= range_from && range_to <= top)) {
+            ranges->Add(CharacterRange::Range(range_from, range_to), zone);
+          }
+        }
+        pos = end + 1;
+      }
+    }
+  }
+#endif  // V8_INTL_SUPPORT
+}
+
+bool CharacterRange::IsCanonical(ZoneList<CharacterRange>* ranges) {
+  DCHECK_NOT_NULL(ranges);
+  int n = ranges->length();
+  if (n <= 1) return true;
+  int max = ranges->at(0).to();
+  for (int i = 1; i < n; i++) {
+    CharacterRange next_range = ranges->at(i);
+    if (next_range.from() <= max + 1) return false;
+    max = next_range.to();
+  }
+  return true;
+}
+
+ZoneList<CharacterRange>* CharacterSet::ranges(Zone* zone) {
+  if (ranges_ == nullptr) {
+    ranges_ = new (zone) ZoneList<CharacterRange>(2, zone);
+    CharacterRange::AddClassEscape(standard_set_type_, ranges_, false, zone);
+  }
+  return ranges_;
+}
+
+// Move a number of elements in a zonelist to another position
+// in the same list. Handles overlapping source and target areas.
+static void MoveRanges(ZoneList<CharacterRange>* list, int from, int to,
+                       int count) {
+  // Ranges are potentially overlapping.
+  if (from < to) {
+    for (int i = count - 1; i >= 0; i--) {
+      list->at(to + i) = list->at(from + i);
+    }
+  } else {
+    for (int i = 0; i < count; i++) {
+      list->at(to + i) = list->at(from + i);
+    }
+  }
+}
+
+static int InsertRangeInCanonicalList(ZoneList<CharacterRange>* list, int count,
+                                      CharacterRange insert) {
+  // Inserts a range into list[0..count[, which must be sorted
+  // by from value and non-overlapping and non-adjacent, using at most
+  // list[0..count] for the result. Returns the number of resulting
+  // canonicalized ranges. Inserting a range may collapse existing ranges into
+  // fewer ranges, so the return value can be anything in the range 1..count+1.
+  uc32 from = insert.from();
+  uc32 to = insert.to();
+  int start_pos = 0;
+  int end_pos = count;
+  for (int i = count - 1; i >= 0; i--) {
+    CharacterRange current = list->at(i);
+    if (current.from() > to + 1) {
+      end_pos = i;
+    } else if (current.to() + 1 < from) {
+      start_pos = i + 1;
+      break;
+    }
+  }
+
+  // Inserted range overlaps, or is adjacent to, ranges at positions
+  // [start_pos..end_pos[. Ranges before start_pos or at or after end_pos are
+  // not affected by the insertion.
+  // If start_pos == end_pos, the range must be inserted before start_pos.
+  // if start_pos < end_pos, the entire range from start_pos to end_pos
+  // must be merged with the insert range.
+
+  if (start_pos == end_pos) {
+    // Insert between existing ranges at position start_pos.
+    if (start_pos < count) {
+      MoveRanges(list, start_pos, start_pos + 1, count - start_pos);
+    }
+    list->at(start_pos) = insert;
+    return count + 1;
+  }
+  if (start_pos + 1 == end_pos) {
+    // Replace single existing range at position start_pos.
+    CharacterRange to_replace = list->at(start_pos);
+    int new_from = Min(to_replace.from(), from);
+    int new_to = Max(to_replace.to(), to);
+    list->at(start_pos) = CharacterRange::Range(new_from, new_to);
+    return count;
+  }
+  // Replace a number of existing ranges from start_pos to end_pos - 1.
+  // Move the remaining ranges down.
+
+  int new_from = Min(list->at(start_pos).from(), from);
+  int new_to = Max(list->at(end_pos - 1).to(), to);
+  if (end_pos < count) {
+    MoveRanges(list, end_pos, start_pos + 1, count - end_pos);
+  }
+  list->at(start_pos) = CharacterRange::Range(new_from, new_to);
+  return count - (end_pos - start_pos) + 1;
+}
+
+void CharacterSet::Canonicalize() {
+  // Special/default classes are always considered canonical. The result
+  // of calling ranges() will be sorted.
+  if (ranges_ == nullptr) return;
+  CharacterRange::Canonicalize(ranges_);
+}
+
+void CharacterRange::Canonicalize(ZoneList<CharacterRange>* character_ranges) {
+  if (character_ranges->length() <= 1) return;
+  // Check whether ranges are already canonical (increasing, non-overlapping,
+  // non-adjacent).
+  int n = character_ranges->length();
+  int max = character_ranges->at(0).to();
+  int i = 1;
+  while (i < n) {
+    CharacterRange current = character_ranges->at(i);
+    if (current.from() <= max + 1) {
+      break;
+    }
+    max = current.to();
+    i++;
+  }
+  // Canonical until the i'th range. If that's all of them, we are done.
+  if (i == n) return;
+
+  // The ranges at index i and forward are not canonicalized. Make them so by
+  // doing the equivalent of insertion sort (inserting each into the previous
+  // list, in order).
+  // Notice that inserting a range can reduce the number of ranges in the
+  // result due to combining of adjacent and overlapping ranges.
+  int read = i;           // Range to insert.
+  int num_canonical = i;  // Length of canonicalized part of list.
+  do {
+    num_canonical = InsertRangeInCanonicalList(character_ranges, num_canonical,
+                                               character_ranges->at(read));
+    read++;
+  } while (read < n);
+  character_ranges->Rewind(num_canonical);
+
+  DCHECK(CharacterRange::IsCanonical(character_ranges));
+}
+
+void CharacterRange::Negate(ZoneList<CharacterRange>* ranges,
+                            ZoneList<CharacterRange>* negated_ranges,
+                            Zone* zone) {
+  DCHECK(CharacterRange::IsCanonical(ranges));
+  DCHECK_EQ(0, negated_ranges->length());
+  int range_count = ranges->length();
+  uc32 from = 0;
+  int i = 0;
+  if (range_count > 0 && ranges->at(0).from() == 0) {
+    from = ranges->at(0).to() + 1;
+    i = 1;
+  }
+  while (i < range_count) {
+    CharacterRange range = ranges->at(i);
+    negated_ranges->Add(CharacterRange::Range(from, range.from() - 1), zone);
+    from = range.to() + 1;
+    i++;
+  }
+  if (from < String::kMaxCodePoint) {
+    negated_ranges->Add(CharacterRange::Range(from, String::kMaxCodePoint),
+                        zone);
+  }
+}
+
+// Scoped object to keep track of how much we unroll quantifier loops in the
+// regexp graph generator.
+class RegExpExpansionLimiter {
+ public:
+  static const int kMaxExpansionFactor = 6;
+  RegExpExpansionLimiter(RegExpCompiler* compiler, int factor)
+      : compiler_(compiler),
+        saved_expansion_factor_(compiler->current_expansion_factor()),
+        ok_to_expand_(saved_expansion_factor_ <= kMaxExpansionFactor) {
+    DCHECK_LT(0, factor);
+    if (ok_to_expand_) {
+      if (factor > kMaxExpansionFactor) {
+        // Avoid integer overflow of the current expansion factor.
+        ok_to_expand_ = false;
+        compiler->set_current_expansion_factor(kMaxExpansionFactor + 1);
+      } else {
+        int new_factor = saved_expansion_factor_ * factor;
+        ok_to_expand_ = (new_factor <= kMaxExpansionFactor);
+        compiler->set_current_expansion_factor(new_factor);
+      }
+    }
+  }
+
+  ~RegExpExpansionLimiter() {
+    compiler_->set_current_expansion_factor(saved_expansion_factor_);
+  }
+
+  bool ok_to_expand() { return ok_to_expand_; }
+
+ private:
+  RegExpCompiler* compiler_;
+  int saved_expansion_factor_;
+  bool ok_to_expand_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpExpansionLimiter);
+};
+
+RegExpNode* RegExpQuantifier::ToNode(int min, int max, bool is_greedy,
+                                     RegExpTree* body, RegExpCompiler* compiler,
+                                     RegExpNode* on_success,
+                                     bool not_at_start) {
+  // x{f, t} becomes this:
+  //
+  //             (r++)<-.
+  //               |     `
+  //               |     (x)
+  //               v     ^
+  //      (r=0)-->(?)---/ [if r < t]
+  //               |
+  //   [if r >= f] \----> ...
+  //
+
+  // 15.10.2.5 RepeatMatcher algorithm.
+  // The parser has already eliminated the case where max is 0.  In the case
+  // where max_match is zero the parser has removed the quantifier if min was
+  // > 0 and removed the atom if min was 0.  See AddQuantifierToAtom.
+
+  // If we know that we cannot match zero length then things are a little
+  // simpler since we don't need to make the special zero length match check
+  // from step 2.1.  If the min and max are small we can unroll a little in
+  // this case.
+  static const int kMaxUnrolledMinMatches = 3;  // Unroll (foo)+ and (foo){3,}
+  static const int kMaxUnrolledMaxMatches = 3;  // Unroll (foo)? and (foo){x,3}
+  if (max == 0) return on_success;  // This can happen due to recursion.
+  bool body_can_be_empty = (body->min_match() == 0);
+  int body_start_reg = RegExpCompiler::kNoRegister;
+  Interval capture_registers = body->CaptureRegisters();
+  bool needs_capture_clearing = !capture_registers.is_empty();
+  Zone* zone = compiler->zone();
+
+  if (body_can_be_empty) {
+    body_start_reg = compiler->AllocateRegister();
+  } else if (compiler->optimize() && !needs_capture_clearing) {
+    // Only unroll if there are no captures and the body can't be
+    // empty.
+    {
+      RegExpExpansionLimiter limiter(compiler, min + ((max != min) ? 1 : 0));
+      if (min > 0 && min <= kMaxUnrolledMinMatches && limiter.ok_to_expand()) {
+        int new_max = (max == kInfinity) ? max : max - min;
+        // Recurse once to get the loop or optional matches after the fixed
+        // ones.
+        RegExpNode* answer =
+            ToNode(0, new_max, is_greedy, body, compiler, on_success, true);
+        // Unroll the forced matches from 0 to min.  This can cause chains of
+        // TextNodes (which the parser does not generate).  These should be
+        // combined if it turns out they hinder good code generation.
+        for (int i = 0; i < min; i++) {
+          answer = body->ToNode(compiler, answer);
+        }
+        return answer;
+      }
+    }
+    if (max <= kMaxUnrolledMaxMatches && min == 0) {
+      DCHECK_LT(0, max);  // Due to the 'if' above.
+      RegExpExpansionLimiter limiter(compiler, max);
+      if (limiter.ok_to_expand()) {
+        // Unroll the optional matches up to max.
+        RegExpNode* answer = on_success;
+        for (int i = 0; i < max; i++) {
+          ChoiceNode* alternation = new (zone) ChoiceNode(2, zone);
+          if (is_greedy) {
+            alternation->AddAlternative(
+                GuardedAlternative(body->ToNode(compiler, answer)));
+            alternation->AddAlternative(GuardedAlternative(on_success));
+          } else {
+            alternation->AddAlternative(GuardedAlternative(on_success));
+            alternation->AddAlternative(
+                GuardedAlternative(body->ToNode(compiler, answer)));
+          }
+          answer = alternation;
+          if (not_at_start && !compiler->read_backward()) {
+            alternation->set_not_at_start();
+          }
+        }
+        return answer;
+      }
+    }
+  }
+  bool has_min = min > 0;
+  bool has_max = max < RegExpTree::kInfinity;
+  bool needs_counter = has_min || has_max;
+  int reg_ctr = needs_counter ? compiler->AllocateRegister()
+                              : RegExpCompiler::kNoRegister;
+  LoopChoiceNode* center = new (zone) LoopChoiceNode(
+      body->min_match() == 0, compiler->read_backward(), min, zone);
+  if (not_at_start && !compiler->read_backward()) center->set_not_at_start();
+  RegExpNode* loop_return =
+      needs_counter ? static_cast<RegExpNode*>(
+                          ActionNode::IncrementRegister(reg_ctr, center))
+                    : static_cast<RegExpNode*>(center);
+  if (body_can_be_empty) {
+    // If the body can be empty we need to check if it was and then
+    // backtrack.
+    loop_return =
+        ActionNode::EmptyMatchCheck(body_start_reg, reg_ctr, min, loop_return);
+  }
+  RegExpNode* body_node = body->ToNode(compiler, loop_return);
+  if (body_can_be_empty) {
+    // If the body can be empty we need to store the start position
+    // so we can bail out if it was empty.
+    body_node = ActionNode::StorePosition(body_start_reg, false, body_node);
+  }
+  if (needs_capture_clearing) {
+    // Before entering the body of this loop we need to clear captures.
+    body_node = ActionNode::ClearCaptures(capture_registers, body_node);
+  }
+  GuardedAlternative body_alt(body_node);
+  if (has_max) {
+    Guard* body_guard = new (zone) Guard(reg_ctr, Guard::LT, max);
+    body_alt.AddGuard(body_guard, zone);
+  }
+  GuardedAlternative rest_alt(on_success);
+  if (has_min) {
+    Guard* rest_guard = new (compiler->zone()) Guard(reg_ctr, Guard::GEQ, min);
+    rest_alt.AddGuard(rest_guard, zone);
+  }
+  if (is_greedy) {
+    center->AddLoopAlternative(body_alt);
+    center->AddContinueAlternative(rest_alt);
+  } else {
+    center->AddContinueAlternative(rest_alt);
+    center->AddLoopAlternative(body_alt);
+  }
+  if (needs_counter) {
+    return ActionNode::SetRegisterForLoop(reg_ctr, 0, center);
+  } else {
+    return center;
+  }
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-compiler.cc b/js/src/regexp/regexp-compiler.cc
new file mode 100644
index 0000000000..9a2aa30dcc
--- /dev/null
+++ b/js/src/regexp/regexp-compiler.cc
@@ -0,0 +1,3834 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-compiler.h"
+
+#include "regexp/regexp-macro-assembler-arch.h"
+#include "regexp/regexp-macro-assembler-tracer.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/locid.h"
+#include "unicode/uniset.h"
+#include "unicode/utypes.h"
+#endif  // V8_INTL_SUPPORT
+
+namespace v8 {
+namespace internal {
+
+using namespace regexp_compiler_constants;  // NOLINT(build/namespaces)
+
+// -------------------------------------------------------------------
+// Implementation of the Irregexp regular expression engine.
+//
+// The Irregexp regular expression engine is intended to be a complete
+// implementation of ECMAScript regular expressions.  It generates either
+// bytecodes or native code.
+
+//   The Irregexp regexp engine is structured in three steps.
+//   1) The parser generates an abstract syntax tree.  See ast.cc.
+//   2) From the AST a node network is created.  The nodes are all
+//      subclasses of RegExpNode.  The nodes represent states when
+//      executing a regular expression.  Several optimizations are
+//      performed on the node network.
+//   3) From the nodes we generate either byte codes or native code
+//      that can actually execute the regular expression (perform
+//      the search).  The code generation step is described in more
+//      detail below.
+
+// Code generation.
+//
+//   The nodes are divided into four main categories.
+//   * Choice nodes
+//        These represent places where the regular expression can
+//        match in more than one way.  For example on entry to an
+//        alternation (foo|bar) or a repetition (*, +, ? or {}).
+//   * Action nodes
+//        These represent places where some action should be
+//        performed.  Examples include recording the current position
+//        in the input string to a register (in order to implement
+//        captures) or other actions on register for example in order
+//        to implement the counters needed for {} repetitions.
+//   * Matching nodes
+//        These attempt to match some element part of the input string.
+//        Examples of elements include character classes, plain strings
+//        or back references.
+//   * End nodes
+//        These are used to implement the actions required on finding
+//        a successful match or failing to find a match.
+//
+//   The code generated (whether as byte codes or native code) maintains
+//   some state as it runs.  This consists of the following elements:
+//
+//   * The capture registers.  Used for string captures.
+//   * Other registers.  Used for counters etc.
+//   * The current position.
+//   * The stack of backtracking information.  Used when a matching node
+//     fails to find a match and needs to try an alternative.
+//
+// Conceptual regular expression execution model:
+//
+//   There is a simple conceptual model of regular expression execution
+//   which will be presented first.  The actual code generated is a more
+//   efficient simulation of the simple conceptual model:
+//
+//   * Choice nodes are implemented as follows:
+//     For each choice except the last {
+//       push current position
+//       push backtrack code location
+//       <generate code to test for choice>
+//       backtrack code location:
+//       pop current position
+//     }
+//     <generate code to test for last choice>
+//
+//   * Actions nodes are generated as follows
+//     <push affected registers on backtrack stack>
+//     <generate code to perform action>
+//     push backtrack code location
+//     <generate code to test for following nodes>
+//     backtrack code location:
+//     <pop affected registers to restore their state>
+//     <pop backtrack location from stack and go to it>
+//
+//   * Matching nodes are generated as follows:
+//     if input string matches at current position
+//       update current position
+//       <generate code to test for following nodes>
+//     else
+//       <pop backtrack location from stack and go to it>
+//
+//   Thus it can be seen that the current position is saved and restored
+//   by the choice nodes, whereas the registers are saved and restored by
+//   by the action nodes that manipulate them.
+//
+//   The other interesting aspect of this model is that nodes are generated
+//   at the point where they are needed by a recursive call to Emit().  If
+//   the node has already been code generated then the Emit() call will
+//   generate a jump to the previously generated code instead.  In order to
+//   limit recursion it is possible for the Emit() function to put the node
+//   on a work list for later generation and instead generate a jump.  The
+//   destination of the jump is resolved later when the code is generated.
+//
+// Actual regular expression code generation.
+//
+//   Code generation is actually more complicated than the above.  In order
+//   to improve the efficiency of the generated code some optimizations are
+//   performed
+//
+//   * Choice nodes have 1-character lookahead.
+//     A choice node looks at the following character and eliminates some of
+//     the choices immediately based on that character.  This is not yet
+//     implemented.
+//   * Simple greedy loops store reduced backtracking information.
+//     A quantifier like /.*foo/m will greedily match the whole input.  It will
+//     then need to backtrack to a point where it can match "foo".  The naive
+//     implementation of this would push each character position onto the
+//     backtracking stack, then pop them off one by one.  This would use space
+//     proportional to the length of the input string.  However since the "."
+//     can only match in one way and always has a constant length (in this case
+//     of 1) it suffices to store the current position on the top of the stack
+//     once.  Matching now becomes merely incrementing the current position and
+//     backtracking becomes decrementing the current position and checking the
+//     result against the stored current position.  This is faster and saves
+//     space.
+//   * The current state is virtualized.
+//     This is used to defer expensive operations until it is clear that they
+//     are needed and to generate code for a node more than once, allowing
+//     specialized an efficient versions of the code to be created. This is
+//     explained in the section below.
+//
+// Execution state virtualization.
+//
+//   Instead of emitting code, nodes that manipulate the state can record their
+//   manipulation in an object called the Trace.  The Trace object can record a
+//   current position offset, an optional backtrack code location on the top of
+//   the virtualized backtrack stack and some register changes.  When a node is
+//   to be emitted it can flush the Trace or update it.  Flushing the Trace
+//   will emit code to bring the actual state into line with the virtual state.
+//   Avoiding flushing the state can postpone some work (e.g. updates of capture
+//   registers).  Postponing work can save time when executing the regular
+//   expression since it may be found that the work never has to be done as a
+//   failure to match can occur.  In addition it is much faster to jump to a
+//   known backtrack code location than it is to pop an unknown backtrack
+//   location from the stack and jump there.
+//
+//   The virtual state found in the Trace affects code generation.  For example
+//   the virtual state contains the difference between the actual current
+//   position and the virtual current position, and matching code needs to use
+//   this offset to attempt a match in the correct location of the input
+//   string.  Therefore code generated for a non-trivial trace is specialized
+//   to that trace.  The code generator therefore has the ability to generate
+//   code for each node several times.  In order to limit the size of the
+//   generated code there is an arbitrary limit on how many specialized sets of
+//   code may be generated for a given node.  If the limit is reached, the
+//   trace is flushed and a generic version of the code for a node is emitted.
+//   This is subsequently used for that node.  The code emitted for non-generic
+//   trace is not recorded in the node and so it cannot currently be reused in
+//   the event that code generation is requested for an identical trace.
+
+void RegExpTree::AppendToText(RegExpText* text, Zone* zone) { UNREACHABLE(); }
+
+void RegExpAtom::AppendToText(RegExpText* text, Zone* zone) {
+  text->AddElement(TextElement::Atom(this), zone);
+}
+
+void RegExpCharacterClass::AppendToText(RegExpText* text, Zone* zone) {
+  text->AddElement(TextElement::CharClass(this), zone);
+}
+
+void RegExpText::AppendToText(RegExpText* text, Zone* zone) {
+  for (int i = 0; i < elements()->length(); i++)
+    text->AddElement(elements()->at(i), zone);
+}
+
+TextElement TextElement::Atom(RegExpAtom* atom) {
+  return TextElement(ATOM, atom);
+}
+
+TextElement TextElement::CharClass(RegExpCharacterClass* char_class) {
+  return TextElement(CHAR_CLASS, char_class);
+}
+
+int TextElement::length() const {
+  switch (text_type()) {
+    case ATOM:
+      return atom()->length();
+
+    case CHAR_CLASS:
+      return 1;
+  }
+  UNREACHABLE();
+}
+
+class RecursionCheck {
+ public:
+  explicit RecursionCheck(RegExpCompiler* compiler) : compiler_(compiler) {
+    compiler->IncrementRecursionDepth();
+  }
+  ~RecursionCheck() { compiler_->DecrementRecursionDepth(); }
+
+ private:
+  RegExpCompiler* compiler_;
+};
+
+// Attempts to compile the regexp using an Irregexp code generator.  Returns
+// a fixed array or a null handle depending on whether it succeeded.
+RegExpCompiler::RegExpCompiler(Isolate* isolate, Zone* zone, int capture_count,
+                               bool one_byte)
+    : next_register_(2 * (capture_count + 1)),
+      unicode_lookaround_stack_register_(kNoRegister),
+      unicode_lookaround_position_register_(kNoRegister),
+      work_list_(nullptr),
+      recursion_depth_(0),
+      one_byte_(one_byte),
+      reg_exp_too_big_(false),
+      limiting_recursion_(false),
+      optimize_(FLAG_regexp_optimization),
+      read_backward_(false),
+      current_expansion_factor_(1),
+      frequency_collator_(),
+      isolate_(isolate),
+      zone_(zone) {
+  accept_ = new (zone) EndNode(EndNode::ACCEPT, zone);
+  DCHECK_GE(RegExpMacroAssembler::kMaxRegister, next_register_ - 1);
+}
+
+RegExpCompiler::CompilationResult RegExpCompiler::Assemble(
+    Isolate* isolate, RegExpMacroAssembler* macro_assembler, RegExpNode* start,
+    int capture_count, Handle<String> pattern) {
+#ifdef DEBUG
+  if (FLAG_trace_regexp_assembler)
+    macro_assembler_ = new RegExpMacroAssemblerTracer(isolate, macro_assembler);
+  else
+#endif
+    macro_assembler_ = macro_assembler;
+
+  std::vector<RegExpNode*> work_list;
+  work_list_ = &work_list;
+  Label fail;
+  macro_assembler_->PushBacktrack(&fail);
+  Trace new_trace;
+  start->Emit(this, &new_trace);
+  macro_assembler_->Bind(&fail);
+  macro_assembler_->Fail();
+  while (!work_list.empty()) {
+    RegExpNode* node = work_list.back();
+    work_list.pop_back();
+    node->set_on_work_list(false);
+    if (!node->label()->is_bound()) node->Emit(this, &new_trace);
+  }
+  if (reg_exp_too_big_) {
+    macro_assembler_->AbortedCodeGeneration();
+    return CompilationResult::RegExpTooBig();
+  }
+
+  Handle<HeapObject> code = macro_assembler_->GetCode(pattern);
+  isolate->IncreaseTotalRegexpCodeGenerated(code->Size());
+  work_list_ = nullptr;
+
+#ifdef DEBUG
+  if (FLAG_trace_regexp_assembler) {
+    delete macro_assembler_;
+  }
+#endif
+  return {*code, next_register_};
+}
+
+bool Trace::DeferredAction::Mentions(int that) {
+  if (action_type() == ActionNode::CLEAR_CAPTURES) {
+    Interval range = static_cast<DeferredClearCaptures*>(this)->range();
+    return range.Contains(that);
+  } else {
+    return reg() == that;
+  }
+}
+
+bool Trace::mentions_reg(int reg) {
+  for (DeferredAction* action = actions_; action != nullptr;
+       action = action->next()) {
+    if (action->Mentions(reg)) return true;
+  }
+  return false;
+}
+
+bool Trace::GetStoredPosition(int reg, int* cp_offset) {
+  DCHECK_EQ(0, *cp_offset);
+  for (DeferredAction* action = actions_; action != nullptr;
+       action = action->next()) {
+    if (action->Mentions(reg)) {
+      if (action->action_type() == ActionNode::STORE_POSITION) {
+        *cp_offset = static_cast<DeferredCapture*>(action)->cp_offset();
+        return true;
+      } else {
+        return false;
+      }
+    }
+  }
+  return false;
+}
+
+// A (dynamically-sized) set of unsigned integers that behaves especially well
+// on small integers (< kFirstLimit). May do zone-allocation.
+class DynamicBitSet : public ZoneObject {
+ public:
+  V8_EXPORT_PRIVATE bool Get(unsigned value) const {
+    if (value < kFirstLimit) {
+      return (first_ & (1 << value)) != 0;
+    } else if (remaining_ == nullptr) {
+      return false;
+    } else {
+      return remaining_->Contains(value);
+    }
+  }
+
+  // Destructively set a value in this set.
+  void Set(unsigned value, Zone* zone) {
+    if (value < kFirstLimit) {
+      first_ |= (1 << value);
+    } else {
+      if (remaining_ == nullptr)
+        remaining_ = new (zone) ZoneList<unsigned>(1, zone);
+      if (remaining_->is_empty() || !remaining_->Contains(value))
+        remaining_->Add(value, zone);
+    }
+  }
+
+ private:
+  static constexpr unsigned kFirstLimit = 32;
+
+  uint32_t first_ = 0;
+  ZoneList<unsigned>* remaining_ = nullptr;
+};
+
+int Trace::FindAffectedRegisters(DynamicBitSet* affected_registers,
+                                 Zone* zone) {
+  int max_register = RegExpCompiler::kNoRegister;
+  for (DeferredAction* action = actions_; action != nullptr;
+       action = action->next()) {
+    if (action->action_type() == ActionNode::CLEAR_CAPTURES) {
+      Interval range = static_cast<DeferredClearCaptures*>(action)->range();
+      for (int i = range.from(); i <= range.to(); i++)
+        affected_registers->Set(i, zone);
+      if (range.to() > max_register) max_register = range.to();
+    } else {
+      affected_registers->Set(action->reg(), zone);
+      if (action->reg() > max_register) max_register = action->reg();
+    }
+  }
+  return max_register;
+}
+
+void Trace::RestoreAffectedRegisters(RegExpMacroAssembler* assembler,
+                                     int max_register,
+                                     const DynamicBitSet& registers_to_pop,
+                                     const DynamicBitSet& registers_to_clear) {
+  for (int reg = max_register; reg >= 0; reg--) {
+    if (registers_to_pop.Get(reg)) {
+      assembler->PopRegister(reg);
+    } else if (registers_to_clear.Get(reg)) {
+      int clear_to = reg;
+      while (reg > 0 && registers_to_clear.Get(reg - 1)) {
+        reg--;
+      }
+      assembler->ClearRegisters(reg, clear_to);
+    }
+  }
+}
+
+void Trace::PerformDeferredActions(RegExpMacroAssembler* assembler,
+                                   int max_register,
+                                   const DynamicBitSet& affected_registers,
+                                   DynamicBitSet* registers_to_pop,
+                                   DynamicBitSet* registers_to_clear,
+                                   Zone* zone) {
+  // The "+1" is to avoid a push_limit of zero if stack_limit_slack() is 1.
+  const int push_limit = (assembler->stack_limit_slack() + 1) / 2;
+
+  // Count pushes performed to force a stack limit check occasionally.
+  int pushes = 0;
+
+  for (int reg = 0; reg <= max_register; reg++) {
+    if (!affected_registers.Get(reg)) {
+      continue;
+    }
+
+    // The chronologically first deferred action in the trace
+    // is used to infer the action needed to restore a register
+    // to its previous state (or not, if it's safe to ignore it).
+    enum DeferredActionUndoType { IGNORE, RESTORE, CLEAR };
+    DeferredActionUndoType undo_action = IGNORE;
+
+    int value = 0;
+    bool absolute = false;
+    bool clear = false;
+    static const int kNoStore = kMinInt;
+    int store_position = kNoStore;
+    // This is a little tricky because we are scanning the actions in reverse
+    // historical order (newest first).
+    for (DeferredAction* action = actions_; action != nullptr;
+         action = action->next()) {
+      if (action->Mentions(reg)) {
+        switch (action->action_type()) {
+          case ActionNode::SET_REGISTER_FOR_LOOP: {
+            Trace::DeferredSetRegisterForLoop* psr =
+                static_cast<Trace::DeferredSetRegisterForLoop*>(action);
+            if (!absolute) {
+              value += psr->value();
+              absolute = true;
+            }
+            // SET_REGISTER_FOR_LOOP is only used for newly introduced loop
+            // counters. They can have a significant previous value if they
+            // occur in a loop. TODO(lrn): Propagate this information, so
+            // we can set undo_action to IGNORE if we know there is no value to
+            // restore.
+            undo_action = RESTORE;
+            DCHECK_EQ(store_position, kNoStore);
+            DCHECK(!clear);
+            break;
+          }
+          case ActionNode::INCREMENT_REGISTER:
+            if (!absolute) {
+              value++;
+            }
+            DCHECK_EQ(store_position, kNoStore);
+            DCHECK(!clear);
+            undo_action = RESTORE;
+            break;
+          case ActionNode::STORE_POSITION: {
+            Trace::DeferredCapture* pc =
+                static_cast<Trace::DeferredCapture*>(action);
+            if (!clear && store_position == kNoStore) {
+              store_position = pc->cp_offset();
+            }
+
+            // For captures we know that stores and clears alternate.
+            // Other register, are never cleared, and if the occur
+            // inside a loop, they might be assigned more than once.
+            if (reg <= 1) {
+              // Registers zero and one, aka "capture zero", is
+              // always set correctly if we succeed. There is no
+              // need to undo a setting on backtrack, because we
+              // will set it again or fail.
+              undo_action = IGNORE;
+            } else {
+              undo_action = pc->is_capture() ? CLEAR : RESTORE;
+            }
+            DCHECK(!absolute);
+            DCHECK_EQ(value, 0);
+            break;
+          }
+          case ActionNode::CLEAR_CAPTURES: {
+            // Since we're scanning in reverse order, if we've already
+            // set the position we have to ignore historically earlier
+            // clearing operations.
+            if (store_position == kNoStore) {
+              clear = true;
+            }
+            undo_action = RESTORE;
+            DCHECK(!absolute);
+            DCHECK_EQ(value, 0);
+            break;
+          }
+          default:
+            UNREACHABLE();
+            break;
+        }
+      }
+    }
+    // Prepare for the undo-action (e.g., push if it's going to be popped).
+    if (undo_action == RESTORE) {
+      pushes++;
+      RegExpMacroAssembler::StackCheckFlag stack_check =
+          RegExpMacroAssembler::kNoStackLimitCheck;
+      if (pushes == push_limit) {
+        stack_check = RegExpMacroAssembler::kCheckStackLimit;
+        pushes = 0;
+      }
+
+      assembler->PushRegister(reg, stack_check);
+      registers_to_pop->Set(reg, zone);
+    } else if (undo_action == CLEAR) {
+      registers_to_clear->Set(reg, zone);
+    }
+    // Perform the chronologically last action (or accumulated increment)
+    // for the register.
+    if (store_position != kNoStore) {
+      assembler->WriteCurrentPositionToRegister(reg, store_position);
+    } else if (clear) {
+      assembler->ClearRegisters(reg, reg);
+    } else if (absolute) {
+      assembler->SetRegister(reg, value);
+    } else if (value != 0) {
+      assembler->AdvanceRegister(reg, value);
+    }
+  }
+}
+
+// This is called as we come into a loop choice node and some other tricky
+// nodes.  It normalizes the state of the code generator to ensure we can
+// generate generic code.
+void Trace::Flush(RegExpCompiler* compiler, RegExpNode* successor) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+
+  DCHECK(!is_trivial());
+
+  if (actions_ == nullptr && backtrack() == nullptr) {
+    // Here we just have some deferred cp advances to fix and we are back to
+    // a normal situation.  We may also have to forget some information gained
+    // through a quick check that was already performed.
+    if (cp_offset_ != 0) assembler->AdvanceCurrentPosition(cp_offset_);
+    // Create a new trivial state and generate the node with that.
+    Trace new_state;
+    successor->Emit(compiler, &new_state);
+    return;
+  }
+
+  // Generate deferred actions here along with code to undo them again.
+  DynamicBitSet affected_registers;
+
+  if (backtrack() != nullptr) {
+    // Here we have a concrete backtrack location.  These are set up by choice
+    // nodes and so they indicate that we have a deferred save of the current
+    // position which we may need to emit here.
+    assembler->PushCurrentPosition();
+  }
+
+  int max_register =
+      FindAffectedRegisters(&affected_registers, compiler->zone());
+  DynamicBitSet registers_to_pop;
+  DynamicBitSet registers_to_clear;
+  PerformDeferredActions(assembler, max_register, affected_registers,
+                         &registers_to_pop, &registers_to_clear,
+                         compiler->zone());
+  if (cp_offset_ != 0) {
+    assembler->AdvanceCurrentPosition(cp_offset_);
+  }
+
+  // Create a new trivial state and generate the node with that.
+  Label undo;
+  assembler->PushBacktrack(&undo);
+  if (successor->KeepRecursing(compiler)) {
+    Trace new_state;
+    successor->Emit(compiler, &new_state);
+  } else {
+    compiler->AddWork(successor);
+    assembler->GoTo(successor->label());
+  }
+
+  // On backtrack we need to restore state.
+  assembler->Bind(&undo);
+  RestoreAffectedRegisters(assembler, max_register, registers_to_pop,
+                           registers_to_clear);
+  if (backtrack() == nullptr) {
+    assembler->Backtrack();
+  } else {
+    assembler->PopCurrentPosition();
+    assembler->GoTo(backtrack());
+  }
+}
+
+void NegativeSubmatchSuccess::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+
+  // Omit flushing the trace. We discard the entire stack frame anyway.
+
+  if (!label()->is_bound()) {
+    // We are completely independent of the trace, since we ignore it,
+    // so this code can be used as the generic version.
+    assembler->Bind(label());
+  }
+
+  // Throw away everything on the backtrack stack since the start
+  // of the negative submatch and restore the character position.
+  assembler->ReadCurrentPositionFromRegister(current_position_register_);
+  assembler->ReadStackPointerFromRegister(stack_pointer_register_);
+  if (clear_capture_count_ > 0) {
+    // Clear any captures that might have been performed during the success
+    // of the body of the negative look-ahead.
+    int clear_capture_end = clear_capture_start_ + clear_capture_count_ - 1;
+    assembler->ClearRegisters(clear_capture_start_, clear_capture_end);
+  }
+  // Now that we have unwound the stack we find at the top of the stack the
+  // backtrack that the BeginSubmatch node got.
+  assembler->Backtrack();
+}
+
+void EndNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  if (!trace->is_trivial()) {
+    trace->Flush(compiler, this);
+    return;
+  }
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  if (!label()->is_bound()) {
+    assembler->Bind(label());
+  }
+  switch (action_) {
+    case ACCEPT:
+      assembler->Succeed();
+      return;
+    case BACKTRACK:
+      assembler->GoTo(trace->backtrack());
+      return;
+    case NEGATIVE_SUBMATCH_SUCCESS:
+      // This case is handled in a different virtual method.
+      UNREACHABLE();
+  }
+  UNIMPLEMENTED();
+}
+
+void GuardedAlternative::AddGuard(Guard* guard, Zone* zone) {
+  if (guards_ == nullptr) guards_ = new (zone) ZoneList<Guard*>(1, zone);
+  guards_->Add(guard, zone);
+}
+
+ActionNode* ActionNode::SetRegisterForLoop(int reg, int val,
+                                           RegExpNode* on_success) {
+  ActionNode* result =
+      new (on_success->zone()) ActionNode(SET_REGISTER_FOR_LOOP, on_success);
+  result->data_.u_store_register.reg = reg;
+  result->data_.u_store_register.value = val;
+  return result;
+}
+
+ActionNode* ActionNode::IncrementRegister(int reg, RegExpNode* on_success) {
+  ActionNode* result =
+      new (on_success->zone()) ActionNode(INCREMENT_REGISTER, on_success);
+  result->data_.u_increment_register.reg = reg;
+  return result;
+}
+
+ActionNode* ActionNode::StorePosition(int reg, bool is_capture,
+                                      RegExpNode* on_success) {
+  ActionNode* result =
+      new (on_success->zone()) ActionNode(STORE_POSITION, on_success);
+  result->data_.u_position_register.reg = reg;
+  result->data_.u_position_register.is_capture = is_capture;
+  return result;
+}
+
+ActionNode* ActionNode::ClearCaptures(Interval range, RegExpNode* on_success) {
+  ActionNode* result =
+      new (on_success->zone()) ActionNode(CLEAR_CAPTURES, on_success);
+  result->data_.u_clear_captures.range_from = range.from();
+  result->data_.u_clear_captures.range_to = range.to();
+  return result;
+}
+
+ActionNode* ActionNode::BeginSubmatch(int stack_reg, int position_reg,
+                                      RegExpNode* on_success) {
+  ActionNode* result =
+      new (on_success->zone()) ActionNode(BEGIN_SUBMATCH, on_success);
+  result->data_.u_submatch.stack_pointer_register = stack_reg;
+  result->data_.u_submatch.current_position_register = position_reg;
+  return result;
+}
+
+ActionNode* ActionNode::PositiveSubmatchSuccess(int stack_reg, int position_reg,
+                                                int clear_register_count,
+                                                int clear_register_from,
+                                                RegExpNode* on_success) {
+  ActionNode* result = new (on_success->zone())
+      ActionNode(POSITIVE_SUBMATCH_SUCCESS, on_success);
+  result->data_.u_submatch.stack_pointer_register = stack_reg;
+  result->data_.u_submatch.current_position_register = position_reg;
+  result->data_.u_submatch.clear_register_count = clear_register_count;
+  result->data_.u_submatch.clear_register_from = clear_register_from;
+  return result;
+}
+
+ActionNode* ActionNode::EmptyMatchCheck(int start_register,
+                                        int repetition_register,
+                                        int repetition_limit,
+                                        RegExpNode* on_success) {
+  ActionNode* result =
+      new (on_success->zone()) ActionNode(EMPTY_MATCH_CHECK, on_success);
+  result->data_.u_empty_match_check.start_register = start_register;
+  result->data_.u_empty_match_check.repetition_register = repetition_register;
+  result->data_.u_empty_match_check.repetition_limit = repetition_limit;
+  return result;
+}
+
+#define DEFINE_ACCEPT(Type) \
+  void Type##Node::Accept(NodeVisitor* visitor) { visitor->Visit##Type(this); }
+FOR_EACH_NODE_TYPE(DEFINE_ACCEPT)
+#undef DEFINE_ACCEPT
+
+// -------------------------------------------------------------------
+// Emit code.
+
+void ChoiceNode::GenerateGuard(RegExpMacroAssembler* macro_assembler,
+                               Guard* guard, Trace* trace) {
+  switch (guard->op()) {
+    case Guard::LT:
+      DCHECK(!trace->mentions_reg(guard->reg()));
+      macro_assembler->IfRegisterGE(guard->reg(), guard->value(),
+                                    trace->backtrack());
+      break;
+    case Guard::GEQ:
+      DCHECK(!trace->mentions_reg(guard->reg()));
+      macro_assembler->IfRegisterLT(guard->reg(), guard->value(),
+                                    trace->backtrack());
+      break;
+  }
+}
+
+// Returns the number of characters in the equivalence class, omitting those
+// that cannot occur in the source string because it is Latin1.
+static int GetCaseIndependentLetters(Isolate* isolate, uc16 character,
+                                     bool one_byte_subject,
+                                     unibrow::uchar* letters,
+                                     int letter_length) {
+#ifdef V8_INTL_SUPPORT
+  // Special case for U+017F which has upper case in ASCII range.
+  if (character == 0x017f) {
+    letters[0] = character;
+    return 1;
+  }
+  icu::UnicodeSet set;
+  set.add(character);
+  set = set.closeOver(USET_CASE_INSENSITIVE);
+  int32_t range_count = set.getRangeCount();
+  int items = 0;
+  for (int32_t i = 0; i < range_count; i++) {
+    UChar32 start = set.getRangeStart(i);
+    UChar32 end = set.getRangeEnd(i);
+    CHECK(end - start + items <= letter_length);
+    // Only add to the output if character is not in ASCII range
+    // or the case equivalent character is in ASCII range.
+    // #sec-runtime-semantics-canonicalize-ch
+    // 3.g If the numeric value of ch ≥ 128 and the numeric value of cu < 128,
+    //     return ch.
+    if (!((start >= 128) && (character < 128))) {
+      // No range have start and end span across code point 128.
+      DCHECK((start >= 128) == (end >= 128));
+      for (UChar32 cu = start; cu <= end; cu++) {
+        if (one_byte_subject && cu > String::kMaxOneByteCharCode) break;
+        letters[items++] = (unibrow::uchar)(cu);
+      }
+    }
+  }
+  return items;
+#else
+  int length =
+      isolate->jsregexp_uncanonicalize()->get(character, '\0', letters);
+  // Unibrow returns 0 or 1 for characters where case independence is
+  // trivial.
+  if (length == 0) {
+    letters[0] = character;
+    length = 1;
+  }
+
+  if (one_byte_subject) {
+    int new_length = 0;
+    for (int i = 0; i < length; i++) {
+      if (letters[i] <= String::kMaxOneByteCharCode) {
+        letters[new_length++] = letters[i];
+      }
+    }
+    length = new_length;
+  }
+
+  return length;
+#endif  // V8_INTL_SUPPORT
+}
+
+static inline bool EmitSimpleCharacter(Isolate* isolate,
+                                       RegExpCompiler* compiler, uc16 c,
+                                       Label* on_failure, int cp_offset,
+                                       bool check, bool preloaded) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  bool bound_checked = false;
+  if (!preloaded) {
+    assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
+    bound_checked = true;
+  }
+  assembler->CheckNotCharacter(c, on_failure);
+  return bound_checked;
+}
+
+// Only emits non-letters (things that don't have case).  Only used for case
+// independent matches.
+static inline bool EmitAtomNonLetter(Isolate* isolate, RegExpCompiler* compiler,
+                                     uc16 c, Label* on_failure, int cp_offset,
+                                     bool check, bool preloaded) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  bool one_byte = compiler->one_byte();
+  unibrow::uchar chars[4];
+  int length = GetCaseIndependentLetters(isolate, c, one_byte, chars, 4);
+  if (length < 1) {
+    // This can't match.  Must be an one-byte subject and a non-one-byte
+    // character.  We do not need to do anything since the one-byte pass
+    // already handled this.
+    return false;  // Bounds not checked.
+  }
+  bool checked = false;
+  // We handle the length > 1 case in a later pass.
+  if (length == 1) {
+    if (one_byte && c > String::kMaxOneByteCharCodeU) {
+      // Can't match - see above.
+      return false;  // Bounds not checked.
+    }
+    if (!preloaded) {
+      macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
+      checked = check;
+    }
+    macro_assembler->CheckNotCharacter(c, on_failure);
+  }
+  return checked;
+}
+
+static bool ShortCutEmitCharacterPair(RegExpMacroAssembler* macro_assembler,
+                                      bool one_byte, uc16 c1, uc16 c2,
+                                      Label* on_failure) {
+  uc16 char_mask;
+  if (one_byte) {
+    char_mask = String::kMaxOneByteCharCode;
+  } else {
+    char_mask = String::kMaxUtf16CodeUnit;
+  }
+  uc16 exor = c1 ^ c2;
+  // Check whether exor has only one bit set.
+  if (((exor - 1) & exor) == 0) {
+    // If c1 and c2 differ only by one bit.
+    // Ecma262UnCanonicalize always gives the highest number last.
+    DCHECK(c2 > c1);
+    uc16 mask = char_mask ^ exor;
+    macro_assembler->CheckNotCharacterAfterAnd(c1, mask, on_failure);
+    return true;
+  }
+  DCHECK(c2 > c1);
+  uc16 diff = c2 - c1;
+  if (((diff - 1) & diff) == 0 && c1 >= diff) {
+    // If the characters differ by 2^n but don't differ by one bit then
+    // subtract the difference from the found character, then do the or
+    // trick.  We avoid the theoretical case where negative numbers are
+    // involved in order to simplify code generation.
+    uc16 mask = char_mask ^ diff;
+    macro_assembler->CheckNotCharacterAfterMinusAnd(c1 - diff, diff, mask,
+                                                    on_failure);
+    return true;
+  }
+  return false;
+}
+
+using EmitCharacterFunction = bool(Isolate* isolate, RegExpCompiler* compiler,
+                                   uc16 c, Label* on_failure, int cp_offset,
+                                   bool check, bool preloaded);
+
+// Only emits letters (things that have case).  Only used for case independent
+// matches.
+static inline bool EmitAtomLetter(Isolate* isolate, RegExpCompiler* compiler,
+                                  uc16 c, Label* on_failure, int cp_offset,
+                                  bool check, bool preloaded) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  bool one_byte = compiler->one_byte();
+  unibrow::uchar chars[4];
+  int length = GetCaseIndependentLetters(isolate, c, one_byte, chars, 4);
+  if (length <= 1) return false;
+  // We may not need to check against the end of the input string
+  // if this character lies before a character that matched.
+  if (!preloaded) {
+    macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
+  }
+  Label ok;
+  switch (length) {
+    case 2: {
+      if (ShortCutEmitCharacterPair(macro_assembler, one_byte, chars[0],
+                                    chars[1], on_failure)) {
+      } else {
+        macro_assembler->CheckCharacter(chars[0], &ok);
+        macro_assembler->CheckNotCharacter(chars[1], on_failure);
+        macro_assembler->Bind(&ok);
+      }
+      break;
+    }
+    case 4:
+      macro_assembler->CheckCharacter(chars[3], &ok);
+      V8_FALLTHROUGH;
+    case 3:
+      macro_assembler->CheckCharacter(chars[0], &ok);
+      macro_assembler->CheckCharacter(chars[1], &ok);
+      macro_assembler->CheckNotCharacter(chars[2], on_failure);
+      macro_assembler->Bind(&ok);
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return true;
+}
+
+static void EmitBoundaryTest(RegExpMacroAssembler* masm, int border,
+                             Label* fall_through, Label* above_or_equal,
+                             Label* below) {
+  if (below != fall_through) {
+    masm->CheckCharacterLT(border, below);
+    if (above_or_equal != fall_through) masm->GoTo(above_or_equal);
+  } else {
+    masm->CheckCharacterGT(border - 1, above_or_equal);
+  }
+}
+
+static void EmitDoubleBoundaryTest(RegExpMacroAssembler* masm, int first,
+                                   int last, Label* fall_through,
+                                   Label* in_range, Label* out_of_range) {
+  if (in_range == fall_through) {
+    if (first == last) {
+      masm->CheckNotCharacter(first, out_of_range);
+    } else {
+      masm->CheckCharacterNotInRange(first, last, out_of_range);
+    }
+  } else {
+    if (first == last) {
+      masm->CheckCharacter(first, in_range);
+    } else {
+      masm->CheckCharacterInRange(first, last, in_range);
+    }
+    if (out_of_range != fall_through) masm->GoTo(out_of_range);
+  }
+}
+
+// even_label is for ranges[i] to ranges[i + 1] where i - start_index is even.
+// odd_label is for ranges[i] to ranges[i + 1] where i - start_index is odd.
+static void EmitUseLookupTable(RegExpMacroAssembler* masm,
+                               ZoneList<int>* ranges, int start_index,
+                               int end_index, int min_char, Label* fall_through,
+                               Label* even_label, Label* odd_label) {
+  static const int kSize = RegExpMacroAssembler::kTableSize;
+  static const int kMask = RegExpMacroAssembler::kTableMask;
+
+  int base = (min_char & ~kMask);
+  USE(base);
+
+  // Assert that everything is on one kTableSize page.
+  for (int i = start_index; i <= end_index; i++) {
+    DCHECK_EQ(ranges->at(i) & ~kMask, base);
+  }
+  DCHECK(start_index == 0 || (ranges->at(start_index - 1) & ~kMask) <= base);
+
+  char templ[kSize];
+  Label* on_bit_set;
+  Label* on_bit_clear;
+  int bit;
+  if (even_label == fall_through) {
+    on_bit_set = odd_label;
+    on_bit_clear = even_label;
+    bit = 1;
+  } else {
+    on_bit_set = even_label;
+    on_bit_clear = odd_label;
+    bit = 0;
+  }
+  for (int i = 0; i < (ranges->at(start_index) & kMask) && i < kSize; i++) {
+    templ[i] = bit;
+  }
+  int j = 0;
+  bit ^= 1;
+  for (int i = start_index; i < end_index; i++) {
+    for (j = (ranges->at(i) & kMask); j < (ranges->at(i + 1) & kMask); j++) {
+      templ[j] = bit;
+    }
+    bit ^= 1;
+  }
+  for (int i = j; i < kSize; i++) {
+    templ[i] = bit;
+  }
+  Factory* factory = masm->isolate()->factory();
+  // TODO(erikcorry): Cache these.
+  Handle<ByteArray> ba = factory->NewByteArray(kSize, AllocationType::kOld);
+  for (int i = 0; i < kSize; i++) {
+    ba->set(i, templ[i]);
+  }
+  masm->CheckBitInTable(ba, on_bit_set);
+  if (on_bit_clear != fall_through) masm->GoTo(on_bit_clear);
+}
+
+static void CutOutRange(RegExpMacroAssembler* masm, ZoneList<int>* ranges,
+                        int start_index, int end_index, int cut_index,
+                        Label* even_label, Label* odd_label) {
+  bool odd = (((cut_index - start_index) & 1) == 1);
+  Label* in_range_label = odd ? odd_label : even_label;
+  Label dummy;
+  EmitDoubleBoundaryTest(masm, ranges->at(cut_index),
+                         ranges->at(cut_index + 1) - 1, &dummy, in_range_label,
+                         &dummy);
+  DCHECK(!dummy.is_linked());
+  // Cut out the single range by rewriting the array.  This creates a new
+  // range that is a merger of the two ranges on either side of the one we
+  // are cutting out.  The oddity of the labels is preserved.
+  for (int j = cut_index; j > start_index; j--) {
+    ranges->at(j) = ranges->at(j - 1);
+  }
+  for (int j = cut_index + 1; j < end_index; j++) {
+    ranges->at(j) = ranges->at(j + 1);
+  }
+}
+
+// Unicode case.  Split the search space into kSize spaces that are handled
+// with recursion.
+static void SplitSearchSpace(ZoneList<int>* ranges, int start_index,
+                             int end_index, int* new_start_index,
+                             int* new_end_index, int* border) {
+  static const int kSize = RegExpMacroAssembler::kTableSize;
+  static const int kMask = RegExpMacroAssembler::kTableMask;
+
+  int first = ranges->at(start_index);
+  int last = ranges->at(end_index) - 1;
+
+  *new_start_index = start_index;
+  *border = (ranges->at(start_index) & ~kMask) + kSize;
+  while (*new_start_index < end_index) {
+    if (ranges->at(*new_start_index) > *border) break;
+    (*new_start_index)++;
+  }
+  // new_start_index is the index of the first edge that is beyond the
+  // current kSize space.
+
+  // For very large search spaces we do a binary chop search of the non-Latin1
+  // space instead of just going to the end of the current kSize space.  The
+  // heuristics are complicated a little by the fact that any 128-character
+  // encoding space can be quickly tested with a table lookup, so we don't
+  // wish to do binary chop search at a smaller granularity than that.  A
+  // 128-character space can take up a lot of space in the ranges array if,
+  // for example, we only want to match every second character (eg. the lower
+  // case characters on some Unicode pages).
+  int binary_chop_index = (end_index + start_index) / 2;
+  // The first test ensures that we get to the code that handles the Latin1
+  // range with a single not-taken branch, speeding up this important
+  // character range (even non-Latin1 charset-based text has spaces and
+  // punctuation).
+  if (*border - 1 > String::kMaxOneByteCharCode &&  // Latin1 case.
+      end_index - start_index > (*new_start_index - start_index) * 2 &&
+      last - first > kSize * 2 && binary_chop_index > *new_start_index &&
+      ranges->at(binary_chop_index) >= first + 2 * kSize) {
+    int scan_forward_for_section_border = binary_chop_index;
+    int new_border = (ranges->at(binary_chop_index) | kMask) + 1;
+
+    while (scan_forward_for_section_border < end_index) {
+      if (ranges->at(scan_forward_for_section_border) > new_border) {
+        *new_start_index = scan_forward_for_section_border;
+        *border = new_border;
+        break;
+      }
+      scan_forward_for_section_border++;
+    }
+  }
+
+  DCHECK(*new_start_index > start_index);
+  *new_end_index = *new_start_index - 1;
+  if (ranges->at(*new_end_index) == *border) {
+    (*new_end_index)--;
+  }
+  if (*border >= ranges->at(end_index)) {
+    *border = ranges->at(end_index);
+    *new_start_index = end_index;  // Won't be used.
+    *new_end_index = end_index - 1;
+  }
+}
+
+// Gets a series of segment boundaries representing a character class.  If the
+// character is in the range between an even and an odd boundary (counting from
+// start_index) then go to even_label, otherwise go to odd_label.  We already
+// know that the character is in the range of min_char to max_char inclusive.
+// Either label can be nullptr indicating backtracking.  Either label can also
+// be equal to the fall_through label.
+static void GenerateBranches(RegExpMacroAssembler* masm, ZoneList<int>* ranges,
+                             int start_index, int end_index, uc32 min_char,
+                             uc32 max_char, Label* fall_through,
+                             Label* even_label, Label* odd_label) {
+  DCHECK_LE(min_char, String::kMaxUtf16CodeUnit);
+  DCHECK_LE(max_char, String::kMaxUtf16CodeUnit);
+
+  int first = ranges->at(start_index);
+  int last = ranges->at(end_index) - 1;
+
+  DCHECK_LT(min_char, first);
+
+  // Just need to test if the character is before or on-or-after
+  // a particular character.
+  if (start_index == end_index) {
+    EmitBoundaryTest(masm, first, fall_through, even_label, odd_label);
+    return;
+  }
+
+  // Another almost trivial case:  There is one interval in the middle that is
+  // different from the end intervals.
+  if (start_index + 1 == end_index) {
+    EmitDoubleBoundaryTest(masm, first, last, fall_through, even_label,
+                           odd_label);
+    return;
+  }
+
+  // It's not worth using table lookup if there are very few intervals in the
+  // character class.
+  if (end_index - start_index <= 6) {
+    // It is faster to test for individual characters, so we look for those
+    // first, then try arbitrary ranges in the second round.
+    static int kNoCutIndex = -1;
+    int cut = kNoCutIndex;
+    for (int i = start_index; i < end_index; i++) {
+      if (ranges->at(i) == ranges->at(i + 1) - 1) {
+        cut = i;
+        break;
+      }
+    }
+    if (cut == kNoCutIndex) cut = start_index;
+    CutOutRange(masm, ranges, start_index, end_index, cut, even_label,
+                odd_label);
+    DCHECK_GE(end_index - start_index, 2);
+    GenerateBranches(masm, ranges, start_index + 1, end_index - 1, min_char,
+                     max_char, fall_through, even_label, odd_label);
+    return;
+  }
+
+  // If there are a lot of intervals in the regexp, then we will use tables to
+  // determine whether the character is inside or outside the character class.
+  static const int kBits = RegExpMacroAssembler::kTableSizeBits;
+
+  if ((max_char >> kBits) == (min_char >> kBits)) {
+    EmitUseLookupTable(masm, ranges, start_index, end_index, min_char,
+                       fall_through, even_label, odd_label);
+    return;
+  }
+
+  if ((min_char >> kBits) != (first >> kBits)) {
+    masm->CheckCharacterLT(first, odd_label);
+    GenerateBranches(masm, ranges, start_index + 1, end_index, first, max_char,
+                     fall_through, odd_label, even_label);
+    return;
+  }
+
+  int new_start_index = 0;
+  int new_end_index = 0;
+  int border = 0;
+
+  SplitSearchSpace(ranges, start_index, end_index, &new_start_index,
+                   &new_end_index, &border);
+
+  Label handle_rest;
+  Label* above = &handle_rest;
+  if (border == last + 1) {
+    // We didn't find any section that started after the limit, so everything
+    // above the border is one of the terminal labels.
+    above = (end_index & 1) != (start_index & 1) ? odd_label : even_label;
+    DCHECK(new_end_index == end_index - 1);
+  }
+
+  DCHECK_LE(start_index, new_end_index);
+  DCHECK_LE(new_start_index, end_index);
+  DCHECK_LT(start_index, new_start_index);
+  DCHECK_LT(new_end_index, end_index);
+  DCHECK(new_end_index + 1 == new_start_index ||
+         (new_end_index + 2 == new_start_index &&
+          border == ranges->at(new_end_index + 1)));
+  DCHECK_LT(min_char, border - 1);
+  DCHECK_LT(border, max_char);
+  DCHECK_LT(ranges->at(new_end_index), border);
+  DCHECK(border < ranges->at(new_start_index) ||
+         (border == ranges->at(new_start_index) &&
+          new_start_index == end_index && new_end_index == end_index - 1 &&
+          border == last + 1));
+  DCHECK(new_start_index == 0 || border >= ranges->at(new_start_index - 1));
+
+  masm->CheckCharacterGT(border - 1, above);
+  Label dummy;
+  GenerateBranches(masm, ranges, start_index, new_end_index, min_char,
+                   border - 1, &dummy, even_label, odd_label);
+  if (handle_rest.is_linked()) {
+    masm->Bind(&handle_rest);
+    bool flip = (new_start_index & 1) != (start_index & 1);
+    GenerateBranches(masm, ranges, new_start_index, end_index, border, max_char,
+                     &dummy, flip ? odd_label : even_label,
+                     flip ? even_label : odd_label);
+  }
+}
+
+static void EmitCharClass(RegExpMacroAssembler* macro_assembler,
+                          RegExpCharacterClass* cc, bool one_byte,
+                          Label* on_failure, int cp_offset, bool check_offset,
+                          bool preloaded, Zone* zone) {
+  ZoneList<CharacterRange>* ranges = cc->ranges(zone);
+  CharacterRange::Canonicalize(ranges);
+
+  int max_char;
+  if (one_byte) {
+    max_char = String::kMaxOneByteCharCode;
+  } else {
+    max_char = String::kMaxUtf16CodeUnit;
+  }
+
+  int range_count = ranges->length();
+
+  int last_valid_range = range_count - 1;
+  while (last_valid_range >= 0) {
+    CharacterRange& range = ranges->at(last_valid_range);
+    if (range.from() <= max_char) {
+      break;
+    }
+    last_valid_range--;
+  }
+
+  if (last_valid_range < 0) {
+    if (!cc->is_negated()) {
+      macro_assembler->GoTo(on_failure);
+    }
+    if (check_offset) {
+      macro_assembler->CheckPosition(cp_offset, on_failure);
+    }
+    return;
+  }
+
+  if (last_valid_range == 0 && ranges->at(0).IsEverything(max_char)) {
+    if (cc->is_negated()) {
+      macro_assembler->GoTo(on_failure);
+    } else {
+      // This is a common case hit by non-anchored expressions.
+      if (check_offset) {
+        macro_assembler->CheckPosition(cp_offset, on_failure);
+      }
+    }
+    return;
+  }
+
+  if (!preloaded) {
+    macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check_offset);
+  }
+
+  if (cc->is_standard(zone) && macro_assembler->CheckSpecialCharacterClass(
+                                   cc->standard_type(), on_failure)) {
+    return;
+  }
+
+  // A new list with ascending entries.  Each entry is a code unit
+  // where there is a boundary between code units that are part of
+  // the class and code units that are not.  Normally we insert an
+  // entry at zero which goes to the failure label, but if there
+  // was already one there we fall through for success on that entry.
+  // Subsequent entries have alternating meaning (success/failure).
+  ZoneList<int>* range_boundaries =
+      new (zone) ZoneList<int>(last_valid_range, zone);
+
+  bool zeroth_entry_is_failure = !cc->is_negated();
+
+  for (int i = 0; i <= last_valid_range; i++) {
+    CharacterRange& range = ranges->at(i);
+    if (range.from() == 0) {
+      DCHECK_EQ(i, 0);
+      zeroth_entry_is_failure = !zeroth_entry_is_failure;
+    } else {
+      range_boundaries->Add(range.from(), zone);
+    }
+    range_boundaries->Add(range.to() + 1, zone);
+  }
+  int end_index = range_boundaries->length() - 1;
+  if (range_boundaries->at(end_index) > max_char) {
+    end_index--;
+  }
+
+  Label fall_through;
+  GenerateBranches(macro_assembler, range_boundaries,
+                   0,  // start_index.
+                   end_index,
+                   0,  // min_char.
+                   max_char, &fall_through,
+                   zeroth_entry_is_failure ? &fall_through : on_failure,
+                   zeroth_entry_is_failure ? on_failure : &fall_through);
+  macro_assembler->Bind(&fall_through);
+}
+
+RegExpNode::~RegExpNode() = default;
+
+RegExpNode::LimitResult RegExpNode::LimitVersions(RegExpCompiler* compiler,
+                                                  Trace* trace) {
+  // If we are generating a greedy loop then don't stop and don't reuse code.
+  if (trace->stop_node() != nullptr) {
+    return CONTINUE;
+  }
+
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  if (trace->is_trivial()) {
+    if (label_.is_bound() || on_work_list() || !KeepRecursing(compiler)) {
+      // If a generic version is already scheduled to be generated or we have
+      // recursed too deeply then just generate a jump to that code.
+      macro_assembler->GoTo(&label_);
+      // This will queue it up for generation of a generic version if it hasn't
+      // already been queued.
+      compiler->AddWork(this);
+      return DONE;
+    }
+    // Generate generic version of the node and bind the label for later use.
+    macro_assembler->Bind(&label_);
+    return CONTINUE;
+  }
+
+  // We are being asked to make a non-generic version.  Keep track of how many
+  // non-generic versions we generate so as not to overdo it.
+  trace_count_++;
+  if (KeepRecursing(compiler) && compiler->optimize() &&
+      trace_count_ < kMaxCopiesCodeGenerated) {
+    return CONTINUE;
+  }
+
+  // If we get here code has been generated for this node too many times or
+  // recursion is too deep.  Time to switch to a generic version.  The code for
+  // generic versions above can handle deep recursion properly.
+  bool was_limiting = compiler->limiting_recursion();
+  compiler->set_limiting_recursion(true);
+  trace->Flush(compiler, this);
+  compiler->set_limiting_recursion(was_limiting);
+  return DONE;
+}
+
+bool RegExpNode::KeepRecursing(RegExpCompiler* compiler) {
+  return !compiler->limiting_recursion() &&
+         compiler->recursion_depth() <= RegExpCompiler::kMaxRecursion;
+}
+
+void ActionNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                              BoyerMooreLookahead* bm, bool not_at_start) {
+  if (action_type_ == POSITIVE_SUBMATCH_SUCCESS) {
+    // Anything may follow a positive submatch success, thus we need to accept
+    // all characters from this position onwards.
+    bm->SetRest(offset);
+  } else {
+    on_success()->FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
+  }
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+void ActionNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                      RegExpCompiler* compiler, int filled_in,
+                                      bool not_at_start) {
+  if (action_type_ == SET_REGISTER_FOR_LOOP) {
+    on_success()->GetQuickCheckDetailsFromLoopEntry(details, compiler,
+                                                    filled_in, not_at_start);
+  } else {
+    on_success()->GetQuickCheckDetails(details, compiler, filled_in,
+                                       not_at_start);
+  }
+}
+
+void AssertionNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                                 BoyerMooreLookahead* bm, bool not_at_start) {
+  // Match the behaviour of EatsAtLeast on this node.
+  if (assertion_type() == AT_START && not_at_start) return;
+  on_success()->FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+void NegativeLookaroundChoiceNode::GetQuickCheckDetails(
+    QuickCheckDetails* details, RegExpCompiler* compiler, int filled_in,
+    bool not_at_start) {
+  RegExpNode* node = continue_node();
+  return node->GetQuickCheckDetails(details, compiler, filled_in, not_at_start);
+}
+
+// Takes the left-most 1-bit and smears it out, setting all bits to its right.
+static inline uint32_t SmearBitsRight(uint32_t v) {
+  v |= v >> 1;
+  v |= v >> 2;
+  v |= v >> 4;
+  v |= v >> 8;
+  v |= v >> 16;
+  return v;
+}
+
+bool QuickCheckDetails::Rationalize(bool asc) {
+  bool found_useful_op = false;
+  uint32_t char_mask;
+  if (asc) {
+    char_mask = String::kMaxOneByteCharCode;
+  } else {
+    char_mask = String::kMaxUtf16CodeUnit;
+  }
+  mask_ = 0;
+  value_ = 0;
+  int char_shift = 0;
+  for (int i = 0; i < characters_; i++) {
+    Position* pos = &positions_[i];
+    if ((pos->mask & String::kMaxOneByteCharCode) != 0) {
+      found_useful_op = true;
+    }
+    mask_ |= (pos->mask & char_mask) << char_shift;
+    value_ |= (pos->value & char_mask) << char_shift;
+    char_shift += asc ? 8 : 16;
+  }
+  return found_useful_op;
+}
+
+int RegExpNode::EatsAtLeast(bool not_at_start) {
+  return not_at_start ? eats_at_least_.eats_at_least_from_not_start
+                      : eats_at_least_.eats_at_least_from_possibly_start;
+}
+
+EatsAtLeastInfo RegExpNode::EatsAtLeastFromLoopEntry() {
+  // SET_REGISTER_FOR_LOOP is only used to initialize loop counters, and it
+  // implies that the following node must be a LoopChoiceNode. If we need to
+  // set registers to constant values for other reasons, we could introduce a
+  // new action type SET_REGISTER that doesn't imply anything about its
+  // successor.
+  UNREACHABLE();
+}
+
+void RegExpNode::GetQuickCheckDetailsFromLoopEntry(QuickCheckDetails* details,
+                                                   RegExpCompiler* compiler,
+                                                   int characters_filled_in,
+                                                   bool not_at_start) {
+  // See comment in RegExpNode::EatsAtLeastFromLoopEntry.
+  UNREACHABLE();
+}
+
+EatsAtLeastInfo LoopChoiceNode::EatsAtLeastFromLoopEntry() {
+  DCHECK_EQ(alternatives_->length(), 2);  // There's just loop and continue.
+
+  if (read_backward()) {
+    // Can't do anything special for a backward loop, so return the basic values
+    // that we got during analysis.
+    return *eats_at_least_info();
+  }
+
+  // Figure out how much the loop body itself eats, not including anything in
+  // the continuation case. In general, the nodes in the loop body should report
+  // that they eat at least the number eaten by the continuation node, since any
+  // successful match in the loop body must also include the continuation node.
+  // However, in some cases involving positive lookaround, the loop body under-
+  // reports its appetite, so use saturated math here to avoid negative numbers.
+  uint8_t loop_body_from_not_start = base::saturated_cast<uint8_t>(
+      loop_node_->EatsAtLeast(true) - continue_node_->EatsAtLeast(true));
+  uint8_t loop_body_from_possibly_start = base::saturated_cast<uint8_t>(
+      loop_node_->EatsAtLeast(false) - continue_node_->EatsAtLeast(true));
+
+  // Limit the number of loop iterations to avoid overflow in subsequent steps.
+  int loop_iterations = base::saturated_cast<uint8_t>(min_loop_iterations());
+
+  EatsAtLeastInfo result;
+  result.eats_at_least_from_not_start =
+      base::saturated_cast<uint8_t>(loop_iterations * loop_body_from_not_start +
+                                    continue_node_->EatsAtLeast(true));
+  if (loop_iterations > 0 && loop_body_from_possibly_start > 0) {
+    // First loop iteration eats at least one, so all subsequent iterations
+    // and the after-loop chunk are guaranteed to not be at the start.
+    result.eats_at_least_from_possibly_start = base::saturated_cast<uint8_t>(
+        loop_body_from_possibly_start +
+        (loop_iterations - 1) * loop_body_from_not_start +
+        continue_node_->EatsAtLeast(true));
+  } else {
+    // Loop body might eat nothing, so only continue node contributes.
+    result.eats_at_least_from_possibly_start =
+        continue_node_->EatsAtLeast(false);
+  }
+  return result;
+}
+
+bool RegExpNode::EmitQuickCheck(RegExpCompiler* compiler,
+                                Trace* bounds_check_trace, Trace* trace,
+                                bool preload_has_checked_bounds,
+                                Label* on_possible_success,
+                                QuickCheckDetails* details,
+                                bool fall_through_on_failure,
+                                ChoiceNode* predecessor) {
+  DCHECK_NOT_NULL(predecessor);
+  if (details->characters() == 0) return false;
+  GetQuickCheckDetails(details, compiler, 0,
+                       trace->at_start() == Trace::FALSE_VALUE);
+  if (details->cannot_match()) return false;
+  if (!details->Rationalize(compiler->one_byte())) return false;
+  DCHECK(details->characters() == 1 ||
+         compiler->macro_assembler()->CanReadUnaligned());
+  uint32_t mask = details->mask();
+  uint32_t value = details->value();
+
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+
+  if (trace->characters_preloaded() != details->characters()) {
+    DCHECK(trace->cp_offset() == bounds_check_trace->cp_offset());
+    // The bounds check is performed using the minimum number of characters
+    // any choice would eat, so if the bounds check fails, then none of the
+    // choices can succeed, so we can just immediately backtrack, rather
+    // than go to the next choice. The number of characters preloaded may be
+    // less than the number used for the bounds check.
+    int eats_at_least = predecessor->EatsAtLeast(
+        bounds_check_trace->at_start() == Trace::FALSE_VALUE);
+    DCHECK_GE(eats_at_least, details->characters());
+    assembler->LoadCurrentCharacter(
+        trace->cp_offset(), bounds_check_trace->backtrack(),
+        !preload_has_checked_bounds, details->characters(), eats_at_least);
+  }
+
+  bool need_mask = true;
+
+  if (details->characters() == 1) {
+    // If number of characters preloaded is 1 then we used a byte or 16 bit
+    // load so the value is already masked down.
+    uint32_t char_mask;
+    if (compiler->one_byte()) {
+      char_mask = String::kMaxOneByteCharCode;
+    } else {
+      char_mask = String::kMaxUtf16CodeUnit;
+    }
+    if ((mask & char_mask) == char_mask) need_mask = false;
+    mask &= char_mask;
+  } else {
+    // For 2-character preloads in one-byte mode or 1-character preloads in
+    // two-byte mode we also use a 16 bit load with zero extend.
+    static const uint32_t kTwoByteMask = 0xFFFF;
+    static const uint32_t kFourByteMask = 0xFFFFFFFF;
+    if (details->characters() == 2 && compiler->one_byte()) {
+      if ((mask & kTwoByteMask) == kTwoByteMask) need_mask = false;
+    } else if (details->characters() == 1 && !compiler->one_byte()) {
+      if ((mask & kTwoByteMask) == kTwoByteMask) need_mask = false;
+    } else {
+      if (mask == kFourByteMask) need_mask = false;
+    }
+  }
+
+  if (fall_through_on_failure) {
+    if (need_mask) {
+      assembler->CheckCharacterAfterAnd(value, mask, on_possible_success);
+    } else {
+      assembler->CheckCharacter(value, on_possible_success);
+    }
+  } else {
+    if (need_mask) {
+      assembler->CheckNotCharacterAfterAnd(value, mask, trace->backtrack());
+    } else {
+      assembler->CheckNotCharacter(value, trace->backtrack());
+    }
+  }
+  return true;
+}
+
+// Here is the meat of GetQuickCheckDetails (see also the comment on the
+// super-class in the .h file).
+//
+// We iterate along the text object, building up for each character a
+// mask and value that can be used to test for a quick failure to match.
+// The masks and values for the positions will be combined into a single
+// machine word for the current character width in order to be used in
+// generating a quick check.
+void TextNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                    RegExpCompiler* compiler,
+                                    int characters_filled_in,
+                                    bool not_at_start) {
+  // Do not collect any quick check details if the text node reads backward,
+  // since it reads in the opposite direction than we use for quick checks.
+  if (read_backward()) return;
+  Isolate* isolate = compiler->macro_assembler()->isolate();
+  DCHECK(characters_filled_in < details->characters());
+  int characters = details->characters();
+  int char_mask;
+  if (compiler->one_byte()) {
+    char_mask = String::kMaxOneByteCharCode;
+  } else {
+    char_mask = String::kMaxUtf16CodeUnit;
+  }
+  for (int k = 0; k < elements()->length(); k++) {
+    TextElement elm = elements()->at(k);
+    if (elm.text_type() == TextElement::ATOM) {
+      Vector<const uc16> quarks = elm.atom()->data();
+      for (int i = 0; i < characters && i < quarks.length(); i++) {
+        QuickCheckDetails::Position* pos =
+            details->positions(characters_filled_in);
+        uc16 c = quarks[i];
+        if (elm.atom()->ignore_case()) {
+          unibrow::uchar chars[4];
+          int length = GetCaseIndependentLetters(
+              isolate, c, compiler->one_byte(), chars, 4);
+          if (length == 0) {
+            // This can happen because all case variants are non-Latin1, but we
+            // know the input is Latin1.
+            details->set_cannot_match();
+            pos->determines_perfectly = false;
+            return;
+          }
+          if (length == 1) {
+            // This letter has no case equivalents, so it's nice and simple
+            // and the mask-compare will determine definitely whether we have
+            // a match at this character position.
+            pos->mask = char_mask;
+            pos->value = chars[0];
+            pos->determines_perfectly = true;
+          } else {
+            uint32_t common_bits = char_mask;
+            uint32_t bits = chars[0];
+            for (int j = 1; j < length; j++) {
+              uint32_t differing_bits = ((chars[j] & common_bits) ^ bits);
+              common_bits ^= differing_bits;
+              bits &= common_bits;
+            }
+            // If length is 2 and common bits has only one zero in it then
+            // our mask and compare instruction will determine definitely
+            // whether we have a match at this character position.  Otherwise
+            // it can only be an approximate check.
+            uint32_t one_zero = (common_bits | ~char_mask);
+            if (length == 2 && ((~one_zero) & ((~one_zero) - 1)) == 0) {
+              pos->determines_perfectly = true;
+            }
+            pos->mask = common_bits;
+            pos->value = bits;
+          }
+        } else {
+          // Don't ignore case.  Nice simple case where the mask-compare will
+          // determine definitely whether we have a match at this character
+          // position.
+          if (c > char_mask) {
+            details->set_cannot_match();
+            pos->determines_perfectly = false;
+            return;
+          }
+          pos->mask = char_mask;
+          pos->value = c;
+          pos->determines_perfectly = true;
+        }
+        characters_filled_in++;
+        DCHECK(characters_filled_in <= details->characters());
+        if (characters_filled_in == details->characters()) {
+          return;
+        }
+      }
+    } else {
+      QuickCheckDetails::Position* pos =
+          details->positions(characters_filled_in);
+      RegExpCharacterClass* tree = elm.char_class();
+      ZoneList<CharacterRange>* ranges = tree->ranges(zone());
+      DCHECK(!ranges->is_empty());
+      if (tree->is_negated()) {
+        // A quick check uses multi-character mask and compare.  There is no
+        // useful way to incorporate a negative char class into this scheme
+        // so we just conservatively create a mask and value that will always
+        // succeed.
+        pos->mask = 0;
+        pos->value = 0;
+      } else {
+        int first_range = 0;
+        while (ranges->at(first_range).from() > char_mask) {
+          first_range++;
+          if (first_range == ranges->length()) {
+            details->set_cannot_match();
+            pos->determines_perfectly = false;
+            return;
+          }
+        }
+        CharacterRange range = ranges->at(first_range);
+        uc16 from = range.from();
+        uc16 to = range.to();
+        if (to > char_mask) {
+          to = char_mask;
+        }
+        uint32_t differing_bits = (from ^ to);
+        // A mask and compare is only perfect if the differing bits form a
+        // number like 00011111 with one single block of trailing 1s.
+        if ((differing_bits & (differing_bits + 1)) == 0 &&
+            from + differing_bits == to) {
+          pos->determines_perfectly = true;
+        }
+        uint32_t common_bits = ~SmearBitsRight(differing_bits);
+        uint32_t bits = (from & common_bits);
+        for (int i = first_range + 1; i < ranges->length(); i++) {
+          CharacterRange range = ranges->at(i);
+          uc16 from = range.from();
+          uc16 to = range.to();
+          if (from > char_mask) continue;
+          if (to > char_mask) to = char_mask;
+          // Here we are combining more ranges into the mask and compare
+          // value.  With each new range the mask becomes more sparse and
+          // so the chances of a false positive rise.  A character class
+          // with multiple ranges is assumed never to be equivalent to a
+          // mask and compare operation.
+          pos->determines_perfectly = false;
+          uint32_t new_common_bits = (from ^ to);
+          new_common_bits = ~SmearBitsRight(new_common_bits);
+          common_bits &= new_common_bits;
+          bits &= new_common_bits;
+          uint32_t differing_bits = (from & common_bits) ^ bits;
+          common_bits ^= differing_bits;
+          bits &= common_bits;
+        }
+        pos->mask = common_bits;
+        pos->value = bits;
+      }
+      characters_filled_in++;
+      DCHECK(characters_filled_in <= details->characters());
+      if (characters_filled_in == details->characters()) {
+        return;
+      }
+    }
+  }
+  DCHECK(characters_filled_in != details->characters());
+  if (!details->cannot_match()) {
+    on_success()->GetQuickCheckDetails(details, compiler, characters_filled_in,
+                                       true);
+  }
+}
+
+void QuickCheckDetails::Clear() {
+  for (int i = 0; i < characters_; i++) {
+    positions_[i].mask = 0;
+    positions_[i].value = 0;
+    positions_[i].determines_perfectly = false;
+  }
+  characters_ = 0;
+}
+
+void QuickCheckDetails::Advance(int by, bool one_byte) {
+  if (by >= characters_ || by < 0) {
+    DCHECK_IMPLIES(by < 0, characters_ == 0);
+    Clear();
+    return;
+  }
+  DCHECK_LE(characters_ - by, 4);
+  DCHECK_LE(characters_, 4);
+  for (int i = 0; i < characters_ - by; i++) {
+    positions_[i] = positions_[by + i];
+  }
+  for (int i = characters_ - by; i < characters_; i++) {
+    positions_[i].mask = 0;
+    positions_[i].value = 0;
+    positions_[i].determines_perfectly = false;
+  }
+  characters_ -= by;
+  // We could change mask_ and value_ here but we would never advance unless
+  // they had already been used in a check and they won't be used again because
+  // it would gain us nothing.  So there's no point.
+}
+
+void QuickCheckDetails::Merge(QuickCheckDetails* other, int from_index) {
+  DCHECK(characters_ == other->characters_);
+  if (other->cannot_match_) {
+    return;
+  }
+  if (cannot_match_) {
+    *this = *other;
+    return;
+  }
+  for (int i = from_index; i < characters_; i++) {
+    QuickCheckDetails::Position* pos = positions(i);
+    QuickCheckDetails::Position* other_pos = other->positions(i);
+    if (pos->mask != other_pos->mask || pos->value != other_pos->value ||
+        !other_pos->determines_perfectly) {
+      // Our mask-compare operation will be approximate unless we have the
+      // exact same operation on both sides of the alternation.
+      pos->determines_perfectly = false;
+    }
+    pos->mask &= other_pos->mask;
+    pos->value &= pos->mask;
+    other_pos->value &= pos->mask;
+    uc16 differing_bits = (pos->value ^ other_pos->value);
+    pos->mask &= ~differing_bits;
+    pos->value &= pos->mask;
+  }
+}
+
+class VisitMarker {
+ public:
+  explicit VisitMarker(NodeInfo* info) : info_(info) {
+    DCHECK(!info->visited);
+    info->visited = true;
+  }
+  ~VisitMarker() { info_->visited = false; }
+
+ private:
+  NodeInfo* info_;
+};
+
+// Temporarily sets traversed_loop_initialization_node_.
+class LoopInitializationMarker {
+ public:
+  explicit LoopInitializationMarker(LoopChoiceNode* node) : node_(node) {
+    DCHECK(!node_->traversed_loop_initialization_node_);
+    node_->traversed_loop_initialization_node_ = true;
+  }
+  ~LoopInitializationMarker() {
+    DCHECK(node_->traversed_loop_initialization_node_);
+    node_->traversed_loop_initialization_node_ = false;
+  }
+
+ private:
+  LoopChoiceNode* node_;
+  DISALLOW_COPY_AND_ASSIGN(LoopInitializationMarker);
+};
+
+// Temporarily decrements min_loop_iterations_.
+class IterationDecrementer {
+ public:
+  explicit IterationDecrementer(LoopChoiceNode* node) : node_(node) {
+    DCHECK_GT(node_->min_loop_iterations_, 0);
+    --node_->min_loop_iterations_;
+  }
+  ~IterationDecrementer() { ++node_->min_loop_iterations_; }
+
+ private:
+  LoopChoiceNode* node_;
+  DISALLOW_COPY_AND_ASSIGN(IterationDecrementer);
+};
+
+RegExpNode* SeqRegExpNode::FilterOneByte(int depth) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  DCHECK(!info()->visited);
+  VisitMarker marker(info());
+  return FilterSuccessor(depth - 1);
+}
+
+RegExpNode* SeqRegExpNode::FilterSuccessor(int depth) {
+  RegExpNode* next = on_success_->FilterOneByte(depth - 1);
+  if (next == nullptr) return set_replacement(nullptr);
+  on_success_ = next;
+  return set_replacement(this);
+}
+
+// We need to check for the following characters: 0x39C 0x3BC 0x178.
+bool RangeContainsLatin1Equivalents(CharacterRange range) {
+  // TODO(dcarney): this could be a lot more efficient.
+  return range.Contains(0x039C) || range.Contains(0x03BC) ||
+         range.Contains(0x0178);
+}
+
+static bool RangesContainLatin1Equivalents(ZoneList<CharacterRange>* ranges) {
+  for (int i = 0; i < ranges->length(); i++) {
+    // TODO(dcarney): this could be a lot more efficient.
+    if (RangeContainsLatin1Equivalents(ranges->at(i))) return true;
+  }
+  return false;
+}
+
+RegExpNode* TextNode::FilterOneByte(int depth) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  DCHECK(!info()->visited);
+  VisitMarker marker(info());
+  int element_count = elements()->length();
+  for (int i = 0; i < element_count; i++) {
+    TextElement elm = elements()->at(i);
+    if (elm.text_type() == TextElement::ATOM) {
+      Vector<const uc16> quarks = elm.atom()->data();
+      for (int j = 0; j < quarks.length(); j++) {
+        uint16_t c = quarks[j];
+        if (elm.atom()->ignore_case()) {
+          c = unibrow::Latin1::TryConvertToLatin1(c);
+        }
+        if (c > unibrow::Latin1::kMaxChar) return set_replacement(nullptr);
+        // Replace quark in case we converted to Latin-1.
+        uint16_t* writable_quarks = const_cast<uint16_t*>(quarks.begin());
+        writable_quarks[j] = c;
+      }
+    } else {
+      DCHECK(elm.text_type() == TextElement::CHAR_CLASS);
+      RegExpCharacterClass* cc = elm.char_class();
+      ZoneList<CharacterRange>* ranges = cc->ranges(zone());
+      CharacterRange::Canonicalize(ranges);
+      // Now they are in order so we only need to look at the first.
+      int range_count = ranges->length();
+      if (cc->is_negated()) {
+        if (range_count != 0 && ranges->at(0).from() == 0 &&
+            ranges->at(0).to() >= String::kMaxOneByteCharCode) {
+          // This will be handled in a later filter.
+          if (IgnoreCase(cc->flags()) && RangesContainLatin1Equivalents(ranges))
+            continue;
+          return set_replacement(nullptr);
+        }
+      } else {
+        if (range_count == 0 ||
+            ranges->at(0).from() > String::kMaxOneByteCharCode) {
+          // This will be handled in a later filter.
+          if (IgnoreCase(cc->flags()) && RangesContainLatin1Equivalents(ranges))
+            continue;
+          return set_replacement(nullptr);
+        }
+      }
+    }
+  }
+  return FilterSuccessor(depth - 1);
+}
+
+RegExpNode* LoopChoiceNode::FilterOneByte(int depth) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  if (info()->visited) return this;
+  {
+    VisitMarker marker(info());
+
+    RegExpNode* continue_replacement = continue_node_->FilterOneByte(depth - 1);
+    // If we can't continue after the loop then there is no sense in doing the
+    // loop.
+    if (continue_replacement == nullptr) return set_replacement(nullptr);
+  }
+
+  return ChoiceNode::FilterOneByte(depth - 1);
+}
+
+RegExpNode* ChoiceNode::FilterOneByte(int depth) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  if (info()->visited) return this;
+  VisitMarker marker(info());
+  int choice_count = alternatives_->length();
+
+  for (int i = 0; i < choice_count; i++) {
+    GuardedAlternative alternative = alternatives_->at(i);
+    if (alternative.guards() != nullptr &&
+        alternative.guards()->length() != 0) {
+      set_replacement(this);
+      return this;
+    }
+  }
+
+  int surviving = 0;
+  RegExpNode* survivor = nullptr;
+  for (int i = 0; i < choice_count; i++) {
+    GuardedAlternative alternative = alternatives_->at(i);
+    RegExpNode* replacement = alternative.node()->FilterOneByte(depth - 1);
+    DCHECK(replacement != this);  // No missing EMPTY_MATCH_CHECK.
+    if (replacement != nullptr) {
+      alternatives_->at(i).set_node(replacement);
+      surviving++;
+      survivor = replacement;
+    }
+  }
+  if (surviving < 2) return set_replacement(survivor);
+
+  set_replacement(this);
+  if (surviving == choice_count) {
+    return this;
+  }
+  // Only some of the nodes survived the filtering.  We need to rebuild the
+  // alternatives list.
+  ZoneList<GuardedAlternative>* new_alternatives =
+      new (zone()) ZoneList<GuardedAlternative>(surviving, zone());
+  for (int i = 0; i < choice_count; i++) {
+    RegExpNode* replacement =
+        alternatives_->at(i).node()->FilterOneByte(depth - 1);
+    if (replacement != nullptr) {
+      alternatives_->at(i).set_node(replacement);
+      new_alternatives->Add(alternatives_->at(i), zone());
+    }
+  }
+  alternatives_ = new_alternatives;
+  return this;
+}
+
+RegExpNode* NegativeLookaroundChoiceNode::FilterOneByte(int depth) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  if (info()->visited) return this;
+  VisitMarker marker(info());
+  // Alternative 0 is the negative lookahead, alternative 1 is what comes
+  // afterwards.
+  RegExpNode* node = continue_node();
+  RegExpNode* replacement = node->FilterOneByte(depth - 1);
+  if (replacement == nullptr) return set_replacement(nullptr);
+  alternatives_->at(kContinueIndex).set_node(replacement);
+
+  RegExpNode* neg_node = lookaround_node();
+  RegExpNode* neg_replacement = neg_node->FilterOneByte(depth - 1);
+  // If the negative lookahead is always going to fail then
+  // we don't need to check it.
+  if (neg_replacement == nullptr) return set_replacement(replacement);
+  alternatives_->at(kLookaroundIndex).set_node(neg_replacement);
+  return set_replacement(this);
+}
+
+void LoopChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                          RegExpCompiler* compiler,
+                                          int characters_filled_in,
+                                          bool not_at_start) {
+  if (body_can_be_zero_length_ || info()->visited) return;
+  not_at_start = not_at_start || this->not_at_start();
+  DCHECK_EQ(alternatives_->length(), 2);  // There's just loop and continue.
+  if (traversed_loop_initialization_node_ && min_loop_iterations_ > 0 &&
+      loop_node_->EatsAtLeast(not_at_start) >
+          continue_node_->EatsAtLeast(true)) {
+    // Loop body is guaranteed to execute at least once, and consume characters
+    // when it does, meaning the only possible quick checks from this point
+    // begin with the loop body. We may recursively visit this LoopChoiceNode,
+    // but we temporarily decrease its minimum iteration counter so we know when
+    // to check the continue case.
+    IterationDecrementer next_iteration(this);
+    loop_node_->GetQuickCheckDetails(details, compiler, characters_filled_in,
+                                     not_at_start);
+  } else {
+    // Might not consume anything in the loop body, so treat it like a normal
+    // ChoiceNode (and don't recursively visit this node again).
+    VisitMarker marker(info());
+    ChoiceNode::GetQuickCheckDetails(details, compiler, characters_filled_in,
+                                     not_at_start);
+  }
+}
+
+void LoopChoiceNode::GetQuickCheckDetailsFromLoopEntry(
+    QuickCheckDetails* details, RegExpCompiler* compiler,
+    int characters_filled_in, bool not_at_start) {
+  if (traversed_loop_initialization_node_) {
+    // We already entered this loop once, exited via its continuation node, and
+    // followed an outer loop's back-edge to before the loop entry point. We
+    // could try to reset the minimum iteration count to its starting value at
+    // this point, but that seems like more trouble than it's worth. It's safe
+    // to keep going with the current (possibly reduced) minimum iteration
+    // count.
+    GetQuickCheckDetails(details, compiler, characters_filled_in, not_at_start);
+  } else {
+    // We are entering a loop via its counter initialization action, meaning we
+    // are guaranteed to run the loop body at least some minimum number of times
+    // before running the continuation node. Set a flag so that this node knows
+    // (now and any times we visit it again recursively) that it was entered
+    // from the top.
+    LoopInitializationMarker marker(this);
+    GetQuickCheckDetails(details, compiler, characters_filled_in, not_at_start);
+  }
+}
+
+void LoopChoiceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                                  BoyerMooreLookahead* bm, bool not_at_start) {
+  if (body_can_be_zero_length_ || budget <= 0) {
+    bm->SetRest(offset);
+    SaveBMInfo(bm, not_at_start, offset);
+    return;
+  }
+  ChoiceNode::FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+void ChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                      RegExpCompiler* compiler,
+                                      int characters_filled_in,
+                                      bool not_at_start) {
+  not_at_start = (not_at_start || not_at_start_);
+  int choice_count = alternatives_->length();
+  DCHECK_LT(0, choice_count);
+  alternatives_->at(0).node()->GetQuickCheckDetails(
+      details, compiler, characters_filled_in, not_at_start);
+  for (int i = 1; i < choice_count; i++) {
+    QuickCheckDetails new_details(details->characters());
+    RegExpNode* node = alternatives_->at(i).node();
+    node->GetQuickCheckDetails(&new_details, compiler, characters_filled_in,
+                               not_at_start);
+    // Here we merge the quick match details of the two branches.
+    details->Merge(&new_details, characters_filled_in);
+  }
+}
+
+namespace {
+
+// Check for [0-9A-Z_a-z].
+void EmitWordCheck(RegExpMacroAssembler* assembler, Label* word,
+                   Label* non_word, bool fall_through_on_word) {
+  if (assembler->CheckSpecialCharacterClass(
+          fall_through_on_word ? 'w' : 'W',
+          fall_through_on_word ? non_word : word)) {
+    // Optimized implementation available.
+    return;
+  }
+  assembler->CheckCharacterGT('z', non_word);
+  assembler->CheckCharacterLT('0', non_word);
+  assembler->CheckCharacterGT('a' - 1, word);
+  assembler->CheckCharacterLT('9' + 1, word);
+  assembler->CheckCharacterLT('A', non_word);
+  assembler->CheckCharacterLT('Z' + 1, word);
+  if (fall_through_on_word) {
+    assembler->CheckNotCharacter('_', non_word);
+  } else {
+    assembler->CheckCharacter('_', word);
+  }
+}
+
+// Emit the code to check for a ^ in multiline mode (1-character lookbehind
+// that matches newline or the start of input).
+void EmitHat(RegExpCompiler* compiler, RegExpNode* on_success, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+
+  // We will load the previous character into the current character register.
+  Trace new_trace(*trace);
+  new_trace.InvalidateCurrentCharacter();
+
+  // A positive (> 0) cp_offset means we've already successfully matched a
+  // non-empty-width part of the pattern, and thus cannot be at or before the
+  // start of the subject string. We can thus skip both at-start and
+  // bounds-checks when loading the one-character lookbehind.
+  const bool may_be_at_or_before_subject_string_start =
+      new_trace.cp_offset() <= 0;
+
+  Label ok;
+  if (may_be_at_or_before_subject_string_start) {
+    // The start of input counts as a newline in this context, so skip to ok if
+    // we are at the start.
+    assembler->CheckAtStart(new_trace.cp_offset(), &ok);
+  }
+
+  // If we've already checked that we are not at the start of input, it's okay
+  // to load the previous character without bounds checks.
+  const bool can_skip_bounds_check = !may_be_at_or_before_subject_string_start;
+  assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1,
+                                  new_trace.backtrack(), can_skip_bounds_check);
+  if (!assembler->CheckSpecialCharacterClass('n', new_trace.backtrack())) {
+    // Newline means \n, \r, 0x2028 or 0x2029.
+    if (!compiler->one_byte()) {
+      assembler->CheckCharacterAfterAnd(0x2028, 0xFFFE, &ok);
+    }
+    assembler->CheckCharacter('\n', &ok);
+    assembler->CheckNotCharacter('\r', new_trace.backtrack());
+  }
+  assembler->Bind(&ok);
+  on_success->Emit(compiler, &new_trace);
+}
+
+}  // namespace
+
+// Emit the code to handle \b and \B (word-boundary or non-word-boundary).
+void AssertionNode::EmitBoundaryCheck(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  Isolate* isolate = assembler->isolate();
+  Trace::TriBool next_is_word_character = Trace::UNKNOWN;
+  bool not_at_start = (trace->at_start() == Trace::FALSE_VALUE);
+  BoyerMooreLookahead* lookahead = bm_info(not_at_start);
+  if (lookahead == nullptr) {
+    int eats_at_least =
+        Min(kMaxLookaheadForBoyerMoore, EatsAtLeast(not_at_start));
+    if (eats_at_least >= 1) {
+      BoyerMooreLookahead* bm =
+          new (zone()) BoyerMooreLookahead(eats_at_least, compiler, zone());
+      FillInBMInfo(isolate, 0, kRecursionBudget, bm, not_at_start);
+      if (bm->at(0)->is_non_word()) next_is_word_character = Trace::FALSE_VALUE;
+      if (bm->at(0)->is_word()) next_is_word_character = Trace::TRUE_VALUE;
+    }
+  } else {
+    if (lookahead->at(0)->is_non_word())
+      next_is_word_character = Trace::FALSE_VALUE;
+    if (lookahead->at(0)->is_word()) next_is_word_character = Trace::TRUE_VALUE;
+  }
+  bool at_boundary = (assertion_type_ == AssertionNode::AT_BOUNDARY);
+  if (next_is_word_character == Trace::UNKNOWN) {
+    Label before_non_word;
+    Label before_word;
+    if (trace->characters_preloaded() != 1) {
+      assembler->LoadCurrentCharacter(trace->cp_offset(), &before_non_word);
+    }
+    // Fall through on non-word.
+    EmitWordCheck(assembler, &before_word, &before_non_word, false);
+    // Next character is not a word character.
+    assembler->Bind(&before_non_word);
+    Label ok;
+    BacktrackIfPrevious(compiler, trace, at_boundary ? kIsNonWord : kIsWord);
+    assembler->GoTo(&ok);
+
+    assembler->Bind(&before_word);
+    BacktrackIfPrevious(compiler, trace, at_boundary ? kIsWord : kIsNonWord);
+    assembler->Bind(&ok);
+  } else if (next_is_word_character == Trace::TRUE_VALUE) {
+    BacktrackIfPrevious(compiler, trace, at_boundary ? kIsWord : kIsNonWord);
+  } else {
+    DCHECK(next_is_word_character == Trace::FALSE_VALUE);
+    BacktrackIfPrevious(compiler, trace, at_boundary ? kIsNonWord : kIsWord);
+  }
+}
+
+void AssertionNode::BacktrackIfPrevious(
+    RegExpCompiler* compiler, Trace* trace,
+    AssertionNode::IfPrevious backtrack_if_previous) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  Trace new_trace(*trace);
+  new_trace.InvalidateCurrentCharacter();
+
+  Label fall_through;
+  Label* non_word = backtrack_if_previous == kIsNonWord ? new_trace.backtrack()
+                                                        : &fall_through;
+  Label* word = backtrack_if_previous == kIsNonWord ? &fall_through
+                                                    : new_trace.backtrack();
+
+  // A positive (> 0) cp_offset means we've already successfully matched a
+  // non-empty-width part of the pattern, and thus cannot be at or before the
+  // start of the subject string. We can thus skip both at-start and
+  // bounds-checks when loading the one-character lookbehind.
+  const bool may_be_at_or_before_subject_string_start =
+      new_trace.cp_offset() <= 0;
+
+  if (may_be_at_or_before_subject_string_start) {
+    // The start of input counts as a non-word character, so the question is
+    // decided if we are at the start.
+    assembler->CheckAtStart(new_trace.cp_offset(), non_word);
+  }
+
+  // If we've already checked that we are not at the start of input, it's okay
+  // to load the previous character without bounds checks.
+  const bool can_skip_bounds_check = !may_be_at_or_before_subject_string_start;
+  assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1, non_word,
+                                  can_skip_bounds_check);
+  EmitWordCheck(assembler, word, non_word, backtrack_if_previous == kIsNonWord);
+
+  assembler->Bind(&fall_through);
+  on_success()->Emit(compiler, &new_trace);
+}
+
+void AssertionNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                         RegExpCompiler* compiler,
+                                         int filled_in, bool not_at_start) {
+  if (assertion_type_ == AT_START && not_at_start) {
+    details->set_cannot_match();
+    return;
+  }
+  return on_success()->GetQuickCheckDetails(details, compiler, filled_in,
+                                            not_at_start);
+}
+
+void AssertionNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  switch (assertion_type_) {
+    case AT_END: {
+      Label ok;
+      assembler->CheckPosition(trace->cp_offset(), &ok);
+      assembler->GoTo(trace->backtrack());
+      assembler->Bind(&ok);
+      break;
+    }
+    case AT_START: {
+      if (trace->at_start() == Trace::FALSE_VALUE) {
+        assembler->GoTo(trace->backtrack());
+        return;
+      }
+      if (trace->at_start() == Trace::UNKNOWN) {
+        assembler->CheckNotAtStart(trace->cp_offset(), trace->backtrack());
+        Trace at_start_trace = *trace;
+        at_start_trace.set_at_start(Trace::TRUE_VALUE);
+        on_success()->Emit(compiler, &at_start_trace);
+        return;
+      }
+    } break;
+    case AFTER_NEWLINE:
+      EmitHat(compiler, on_success(), trace);
+      return;
+    case AT_BOUNDARY:
+    case AT_NON_BOUNDARY: {
+      EmitBoundaryCheck(compiler, trace);
+      return;
+    }
+  }
+  on_success()->Emit(compiler, trace);
+}
+
+static bool DeterminedAlready(QuickCheckDetails* quick_check, int offset) {
+  if (quick_check == nullptr) return false;
+  if (offset >= quick_check->characters()) return false;
+  return quick_check->positions(offset)->determines_perfectly;
+}
+
+static void UpdateBoundsCheck(int index, int* checked_up_to) {
+  if (index > *checked_up_to) {
+    *checked_up_to = index;
+  }
+}
+
+// We call this repeatedly to generate code for each pass over the text node.
+// The passes are in increasing order of difficulty because we hope one
+// of the first passes will fail in which case we are saved the work of the
+// later passes.  for example for the case independent regexp /%[asdfghjkl]a/
+// we will check the '%' in the first pass, the case independent 'a' in the
+// second pass and the character class in the last pass.
+//
+// The passes are done from right to left, so for example to test for /bar/
+// we will first test for an 'r' with offset 2, then an 'a' with offset 1
+// and then a 'b' with offset 0.  This means we can avoid the end-of-input
+// bounds check most of the time.  In the example we only need to check for
+// end-of-input when loading the putative 'r'.
+//
+// A slight complication involves the fact that the first character may already
+// be fetched into a register by the previous node.  In this case we want to
+// do the test for that character first.  We do this in separate passes.  The
+// 'preloaded' argument indicates that we are doing such a 'pass'.  If such a
+// pass has been performed then subsequent passes will have true in
+// first_element_checked to indicate that that character does not need to be
+// checked again.
+//
+// In addition to all this we are passed a Trace, which can
+// contain an AlternativeGeneration object.  In this AlternativeGeneration
+// object we can see details of any quick check that was already passed in
+// order to get to the code we are now generating.  The quick check can involve
+// loading characters, which means we do not need to recheck the bounds
+// up to the limit the quick check already checked.  In addition the quick
+// check can have involved a mask and compare operation which may simplify
+// or obviate the need for further checks at some character positions.
+void TextNode::TextEmitPass(RegExpCompiler* compiler, TextEmitPassType pass,
+                            bool preloaded, Trace* trace,
+                            bool first_element_checked, int* checked_up_to) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  Isolate* isolate = assembler->isolate();
+  bool one_byte = compiler->one_byte();
+  Label* backtrack = trace->backtrack();
+  QuickCheckDetails* quick_check = trace->quick_check_performed();
+  int element_count = elements()->length();
+  int backward_offset = read_backward() ? -Length() : 0;
+  for (int i = preloaded ? 0 : element_count - 1; i >= 0; i--) {
+    TextElement elm = elements()->at(i);
+    int cp_offset = trace->cp_offset() + elm.cp_offset() + backward_offset;
+    if (elm.text_type() == TextElement::ATOM) {
+      if (SkipPass(pass, elm.atom()->ignore_case())) continue;
+      Vector<const uc16> quarks = elm.atom()->data();
+      for (int j = preloaded ? 0 : quarks.length() - 1; j >= 0; j--) {
+        if (first_element_checked && i == 0 && j == 0) continue;
+        if (DeterminedAlready(quick_check, elm.cp_offset() + j)) continue;
+        EmitCharacterFunction* emit_function = nullptr;
+        uc16 quark = quarks[j];
+        if (elm.atom()->ignore_case()) {
+          // Everywhere else we assume that a non-Latin-1 character cannot match
+          // a Latin-1 character. Avoid the cases where this is assumption is
+          // invalid by using the Latin1 equivalent instead.
+          quark = unibrow::Latin1::TryConvertToLatin1(quark);
+        }
+        switch (pass) {
+          case NON_LATIN1_MATCH:
+            DCHECK(one_byte);
+            if (quark > String::kMaxOneByteCharCode) {
+              assembler->GoTo(backtrack);
+              return;
+            }
+            break;
+          case NON_LETTER_CHARACTER_MATCH:
+            emit_function = &EmitAtomNonLetter;
+            break;
+          case SIMPLE_CHARACTER_MATCH:
+            emit_function = &EmitSimpleCharacter;
+            break;
+          case CASE_CHARACTER_MATCH:
+            emit_function = &EmitAtomLetter;
+            break;
+          default:
+            break;
+        }
+        if (emit_function != nullptr) {
+          bool bounds_check = *checked_up_to < cp_offset + j || read_backward();
+          bool bound_checked =
+              emit_function(isolate, compiler, quark, backtrack, cp_offset + j,
+                            bounds_check, preloaded);
+          if (bound_checked) UpdateBoundsCheck(cp_offset + j, checked_up_to);
+        }
+      }
+    } else {
+      DCHECK_EQ(TextElement::CHAR_CLASS, elm.text_type());
+      if (pass == CHARACTER_CLASS_MATCH) {
+        if (first_element_checked && i == 0) continue;
+        if (DeterminedAlready(quick_check, elm.cp_offset())) continue;
+        RegExpCharacterClass* cc = elm.char_class();
+        bool bounds_check = *checked_up_to < cp_offset || read_backward();
+        EmitCharClass(assembler, cc, one_byte, backtrack, cp_offset,
+                      bounds_check, preloaded, zone());
+        UpdateBoundsCheck(cp_offset, checked_up_to);
+      }
+    }
+  }
+}
+
+int TextNode::Length() {
+  TextElement elm = elements()->last();
+  DCHECK_LE(0, elm.cp_offset());
+  return elm.cp_offset() + elm.length();
+}
+
+bool TextNode::SkipPass(TextEmitPassType pass, bool ignore_case) {
+  if (ignore_case) {
+    return pass == SIMPLE_CHARACTER_MATCH;
+  } else {
+    return pass == NON_LETTER_CHARACTER_MATCH || pass == CASE_CHARACTER_MATCH;
+  }
+}
+
+TextNode* TextNode::CreateForCharacterRanges(Zone* zone,
+                                             ZoneList<CharacterRange>* ranges,
+                                             bool read_backward,
+                                             RegExpNode* on_success,
+                                             JSRegExp::Flags flags) {
+  DCHECK_NOT_NULL(ranges);
+  ZoneList<TextElement>* elms = new (zone) ZoneList<TextElement>(1, zone);
+  elms->Add(TextElement::CharClass(
+                new (zone) RegExpCharacterClass(zone, ranges, flags)),
+            zone);
+  return new (zone) TextNode(elms, read_backward, on_success);
+}
+
+TextNode* TextNode::CreateForSurrogatePair(Zone* zone, CharacterRange lead,
+                                           CharacterRange trail,
+                                           bool read_backward,
+                                           RegExpNode* on_success,
+                                           JSRegExp::Flags flags) {
+  ZoneList<CharacterRange>* lead_ranges = CharacterRange::List(zone, lead);
+  ZoneList<CharacterRange>* trail_ranges = CharacterRange::List(zone, trail);
+  ZoneList<TextElement>* elms = new (zone) ZoneList<TextElement>(2, zone);
+  elms->Add(TextElement::CharClass(
+                new (zone) RegExpCharacterClass(zone, lead_ranges, flags)),
+            zone);
+  elms->Add(TextElement::CharClass(
+                new (zone) RegExpCharacterClass(zone, trail_ranges, flags)),
+            zone);
+  return new (zone) TextNode(elms, read_backward, on_success);
+}
+
+// This generates the code to match a text node.  A text node can contain
+// straight character sequences (possibly to be matched in a case-independent
+// way) and character classes.  For efficiency we do not do this in a single
+// pass from left to right.  Instead we pass over the text node several times,
+// emitting code for some character positions every time.  See the comment on
+// TextEmitPass for details.
+void TextNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  LimitResult limit_result = LimitVersions(compiler, trace);
+  if (limit_result == DONE) return;
+  DCHECK(limit_result == CONTINUE);
+
+  if (trace->cp_offset() + Length() > RegExpMacroAssembler::kMaxCPOffset) {
+    compiler->SetRegExpTooBig();
+    return;
+  }
+
+  if (compiler->one_byte()) {
+    int dummy = 0;
+    TextEmitPass(compiler, NON_LATIN1_MATCH, false, trace, false, &dummy);
+  }
+
+  bool first_elt_done = false;
+  int bound_checked_to = trace->cp_offset() - 1;
+  bound_checked_to += trace->bound_checked_up_to();
+
+  // If a character is preloaded into the current character register then
+  // check that now.
+  if (trace->characters_preloaded() == 1) {
+    for (int pass = kFirstRealPass; pass <= kLastPass; pass++) {
+      TextEmitPass(compiler, static_cast<TextEmitPassType>(pass), true, trace,
+                   false, &bound_checked_to);
+    }
+    first_elt_done = true;
+  }
+
+  for (int pass = kFirstRealPass; pass <= kLastPass; pass++) {
+    TextEmitPass(compiler, static_cast<TextEmitPassType>(pass), false, trace,
+                 first_elt_done, &bound_checked_to);
+  }
+
+  Trace successor_trace(*trace);
+  // If we advance backward, we may end up at the start.
+  successor_trace.AdvanceCurrentPositionInTrace(
+      read_backward() ? -Length() : Length(), compiler);
+  successor_trace.set_at_start(read_backward() ? Trace::UNKNOWN
+                                               : Trace::FALSE_VALUE);
+  RecursionCheck rc(compiler);
+  on_success()->Emit(compiler, &successor_trace);
+}
+
+void Trace::InvalidateCurrentCharacter() { characters_preloaded_ = 0; }
+
+void Trace::AdvanceCurrentPositionInTrace(int by, RegExpCompiler* compiler) {
+  // We don't have an instruction for shifting the current character register
+  // down or for using a shifted value for anything so lets just forget that
+  // we preloaded any characters into it.
+  characters_preloaded_ = 0;
+  // Adjust the offsets of the quick check performed information.  This
+  // information is used to find out what we already determined about the
+  // characters by means of mask and compare.
+  quick_check_performed_.Advance(by, compiler->one_byte());
+  cp_offset_ += by;
+  if (cp_offset_ > RegExpMacroAssembler::kMaxCPOffset) {
+    compiler->SetRegExpTooBig();
+    cp_offset_ = 0;
+  }
+  bound_checked_up_to_ = Max(0, bound_checked_up_to_ - by);
+}
+
+void TextNode::MakeCaseIndependent(Isolate* isolate, bool is_one_byte) {
+  int element_count = elements()->length();
+  for (int i = 0; i < element_count; i++) {
+    TextElement elm = elements()->at(i);
+    if (elm.text_type() == TextElement::CHAR_CLASS) {
+      RegExpCharacterClass* cc = elm.char_class();
+#ifdef V8_INTL_SUPPORT
+      bool case_equivalents_already_added =
+          NeedsUnicodeCaseEquivalents(cc->flags());
+#else
+      bool case_equivalents_already_added = false;
+#endif
+      if (IgnoreCase(cc->flags()) && !case_equivalents_already_added) {
+        // None of the standard character classes is different in the case
+        // independent case and it slows us down if we don't know that.
+        if (cc->is_standard(zone())) continue;
+        ZoneList<CharacterRange>* ranges = cc->ranges(zone());
+        CharacterRange::AddCaseEquivalents(isolate, zone(), ranges,
+                                           is_one_byte);
+      }
+    }
+  }
+}
+
+int TextNode::GreedyLoopTextLength() { return Length(); }
+
+RegExpNode* TextNode::GetSuccessorOfOmnivorousTextNode(
+    RegExpCompiler* compiler) {
+  if (read_backward()) return nullptr;
+  if (elements()->length() != 1) return nullptr;
+  TextElement elm = elements()->at(0);
+  if (elm.text_type() != TextElement::CHAR_CLASS) return nullptr;
+  RegExpCharacterClass* node = elm.char_class();
+  ZoneList<CharacterRange>* ranges = node->ranges(zone());
+  CharacterRange::Canonicalize(ranges);
+  if (node->is_negated()) {
+    return ranges->length() == 0 ? on_success() : nullptr;
+  }
+  if (ranges->length() != 1) return nullptr;
+  uint32_t max_char;
+  if (compiler->one_byte()) {
+    max_char = String::kMaxOneByteCharCode;
+  } else {
+    max_char = String::kMaxUtf16CodeUnit;
+  }
+  return ranges->at(0).IsEverything(max_char) ? on_success() : nullptr;
+}
+
+// Finds the fixed match length of a sequence of nodes that goes from
+// this alternative and back to this choice node.  If there are variable
+// length nodes or other complications in the way then return a sentinel
+// value indicating that a greedy loop cannot be constructed.
+int ChoiceNode::GreedyLoopTextLengthForAlternative(
+    GuardedAlternative* alternative) {
+  int length = 0;
+  RegExpNode* node = alternative->node();
+  // Later we will generate code for all these text nodes using recursion
+  // so we have to limit the max number.
+  int recursion_depth = 0;
+  while (node != this) {
+    if (recursion_depth++ > RegExpCompiler::kMaxRecursion) {
+      return kNodeIsTooComplexForGreedyLoops;
+    }
+    int node_length = node->GreedyLoopTextLength();
+    if (node_length == kNodeIsTooComplexForGreedyLoops) {
+      return kNodeIsTooComplexForGreedyLoops;
+    }
+    length += node_length;
+    SeqRegExpNode* seq_node = static_cast<SeqRegExpNode*>(node);
+    node = seq_node->on_success();
+  }
+  return read_backward() ? -length : length;
+}
+
+void LoopChoiceNode::AddLoopAlternative(GuardedAlternative alt) {
+  DCHECK_NULL(loop_node_);
+  AddAlternative(alt);
+  loop_node_ = alt.node();
+}
+
+void LoopChoiceNode::AddContinueAlternative(GuardedAlternative alt) {
+  DCHECK_NULL(continue_node_);
+  AddAlternative(alt);
+  continue_node_ = alt.node();
+}
+
+void LoopChoiceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  if (trace->stop_node() == this) {
+    // Back edge of greedy optimized loop node graph.
+    int text_length =
+        GreedyLoopTextLengthForAlternative(&(alternatives_->at(0)));
+    DCHECK_NE(kNodeIsTooComplexForGreedyLoops, text_length);
+    // Update the counter-based backtracking info on the stack.  This is an
+    // optimization for greedy loops (see below).
+    DCHECK(trace->cp_offset() == text_length);
+    macro_assembler->AdvanceCurrentPosition(text_length);
+    macro_assembler->GoTo(trace->loop_label());
+    return;
+  }
+  DCHECK_NULL(trace->stop_node());
+  if (!trace->is_trivial()) {
+    trace->Flush(compiler, this);
+    return;
+  }
+  ChoiceNode::Emit(compiler, trace);
+}
+
+int ChoiceNode::CalculatePreloadCharacters(RegExpCompiler* compiler,
+                                           int eats_at_least) {
+  int preload_characters = Min(4, eats_at_least);
+  DCHECK_LE(preload_characters, 4);
+  if (compiler->macro_assembler()->CanReadUnaligned()) {
+    bool one_byte = compiler->one_byte();
+    if (one_byte) {
+      // We can't preload 3 characters because there is no machine instruction
+      // to do that.  We can't just load 4 because we could be reading
+      // beyond the end of the string, which could cause a memory fault.
+      if (preload_characters == 3) preload_characters = 2;
+    } else {
+      if (preload_characters > 2) preload_characters = 2;
+    }
+  } else {
+    if (preload_characters > 1) preload_characters = 1;
+  }
+  return preload_characters;
+}
+
+// This class is used when generating the alternatives in a choice node.  It
+// records the way the alternative is being code generated.
+class AlternativeGeneration : public Malloced {
+ public:
+  AlternativeGeneration()
+      : possible_success(),
+        expects_preload(false),
+        after(),
+        quick_check_details() {}
+  Label possible_success;
+  bool expects_preload;
+  Label after;
+  QuickCheckDetails quick_check_details;
+};
+
+// Creates a list of AlternativeGenerations.  If the list has a reasonable
+// size then it is on the stack, otherwise the excess is on the heap.
+class AlternativeGenerationList {
+ public:
+  AlternativeGenerationList(int count, Zone* zone) : alt_gens_(count, zone) {
+    for (int i = 0; i < count && i < kAFew; i++) {
+      alt_gens_.Add(a_few_alt_gens_ + i, zone);
+    }
+    for (int i = kAFew; i < count; i++) {
+      alt_gens_.Add(new AlternativeGeneration(), zone);
+    }
+  }
+  ~AlternativeGenerationList() {
+    for (int i = kAFew; i < alt_gens_.length(); i++) {
+      delete alt_gens_[i];
+      alt_gens_[i] = nullptr;
+    }
+  }
+
+  AlternativeGeneration* at(int i) { return alt_gens_[i]; }
+
+ private:
+  static const int kAFew = 10;
+  ZoneList<AlternativeGeneration*> alt_gens_;
+  AlternativeGeneration a_few_alt_gens_[kAFew];
+};
+
+void BoyerMoorePositionInfo::Set(int character) {
+  SetInterval(Interval(character, character));
+}
+
+namespace {
+
+ContainedInLattice AddRange(ContainedInLattice containment, const int* ranges,
+                            int ranges_length, Interval new_range) {
+  DCHECK_EQ(1, ranges_length & 1);
+  DCHECK_EQ(String::kMaxCodePoint + 1, ranges[ranges_length - 1]);
+  if (containment == kLatticeUnknown) return containment;
+  bool inside = false;
+  int last = 0;
+  for (int i = 0; i < ranges_length; inside = !inside, last = ranges[i], i++) {
+    // Consider the range from last to ranges[i].
+    // We haven't got to the new range yet.
+    if (ranges[i] <= new_range.from()) continue;
+    // New range is wholly inside last-ranges[i].  Note that new_range.to() is
+    // inclusive, but the values in ranges are not.
+    if (last <= new_range.from() && new_range.to() < ranges[i]) {
+      return Combine(containment, inside ? kLatticeIn : kLatticeOut);
+    }
+    return kLatticeUnknown;
+  }
+  return containment;
+}
+
+int BitsetFirstSetBit(BoyerMoorePositionInfo::Bitset bitset) {
+  STATIC_ASSERT(BoyerMoorePositionInfo::kMapSize ==
+                2 * kInt64Size * kBitsPerByte);
+
+  // Slight fiddling is needed here, since the bitset is of length 128 while
+  // CountTrailingZeros requires an integral type and std::bitset can only
+  // convert to unsigned long long. So we handle the most- and least-significant
+  // bits separately.
+
+  {
+    static constexpr BoyerMoorePositionInfo::Bitset mask(~uint64_t{0});
+    BoyerMoorePositionInfo::Bitset masked_bitset = bitset & mask;
+    STATIC_ASSERT(kInt64Size >= sizeof(decltype(masked_bitset.to_ullong())));
+    uint64_t lsb = masked_bitset.to_ullong();
+    if (lsb != 0) return base::bits::CountTrailingZeros(lsb);
+  }
+
+  {
+    BoyerMoorePositionInfo::Bitset masked_bitset = bitset >> 64;
+    uint64_t msb = masked_bitset.to_ullong();
+    if (msb != 0) return 64 + base::bits::CountTrailingZeros(msb);
+  }
+
+  return -1;
+}
+
+}  // namespace
+
+void BoyerMoorePositionInfo::SetInterval(const Interval& interval) {
+  w_ = AddRange(w_, kWordRanges, kWordRangeCount, interval);
+
+  if (interval.size() >= kMapSize) {
+    map_count_ = kMapSize;
+    map_.set();
+    return;
+  }
+
+  for (int i = interval.from(); i <= interval.to(); i++) {
+    int mod_character = (i & kMask);
+    if (!map_[mod_character]) {
+      map_count_++;
+      map_.set(mod_character);
+    }
+    if (map_count_ == kMapSize) return;
+  }
+}
+
+void BoyerMoorePositionInfo::SetAll() {
+  w_ = kLatticeUnknown;
+  if (map_count_ != kMapSize) {
+    map_count_ = kMapSize;
+    map_.set();
+  }
+}
+
+BoyerMooreLookahead::BoyerMooreLookahead(int length, RegExpCompiler* compiler,
+                                         Zone* zone)
+    : length_(length), compiler_(compiler) {
+  if (compiler->one_byte()) {
+    max_char_ = String::kMaxOneByteCharCode;
+  } else {
+    max_char_ = String::kMaxUtf16CodeUnit;
+  }
+  bitmaps_ = new (zone) ZoneList<BoyerMoorePositionInfo*>(length, zone);
+  for (int i = 0; i < length; i++) {
+    bitmaps_->Add(new (zone) BoyerMoorePositionInfo(), zone);
+  }
+}
+
+// Find the longest range of lookahead that has the fewest number of different
+// characters that can occur at a given position.  Since we are optimizing two
+// different parameters at once this is a tradeoff.
+bool BoyerMooreLookahead::FindWorthwhileInterval(int* from, int* to) {
+  int biggest_points = 0;
+  // If more than 32 characters out of 128 can occur it is unlikely that we can
+  // be lucky enough to step forwards much of the time.
+  const int kMaxMax = 32;
+  for (int max_number_of_chars = 4; max_number_of_chars < kMaxMax;
+       max_number_of_chars *= 2) {
+    biggest_points =
+        FindBestInterval(max_number_of_chars, biggest_points, from, to);
+  }
+  if (biggest_points == 0) return false;
+  return true;
+}
+
+// Find the highest-points range between 0 and length_ where the character
+// information is not too vague.  'Too vague' means that there are more than
+// max_number_of_chars that can occur at this position.  Calculates the number
+// of points as the product of width-of-the-range and
+// probability-of-finding-one-of-the-characters, where the probability is
+// calculated using the frequency distribution of the sample subject string.
+int BoyerMooreLookahead::FindBestInterval(int max_number_of_chars,
+                                          int old_biggest_points, int* from,
+                                          int* to) {
+  int biggest_points = old_biggest_points;
+  static const int kSize = RegExpMacroAssembler::kTableSize;
+  for (int i = 0; i < length_;) {
+    while (i < length_ && Count(i) > max_number_of_chars) i++;
+    if (i == length_) break;
+    int remembered_from = i;
+
+    BoyerMoorePositionInfo::Bitset union_bitset;
+    for (; i < length_ && Count(i) <= max_number_of_chars; i++) {
+      union_bitset |= bitmaps_->at(i)->raw_bitset();
+    }
+
+    int frequency = 0;
+
+    // Iterate only over set bits.
+    int j;
+    while ((j = BitsetFirstSetBit(union_bitset)) != -1) {
+      DCHECK(union_bitset[j]);  // Sanity check.
+      // Add 1 to the frequency to give a small per-character boost for
+      // the cases where our sampling is not good enough and many
+      // characters have a frequency of zero.  This means the frequency
+      // can theoretically be up to 2*kSize though we treat it mostly as
+      // a fraction of kSize.
+      frequency += compiler_->frequency_collator()->Frequency(j) + 1;
+      union_bitset.reset(j);
+    }
+
+    // We use the probability of skipping times the distance we are skipping to
+    // judge the effectiveness of this.  Actually we have a cut-off:  By
+    // dividing by 2 we switch off the skipping if the probability of skipping
+    // is less than 50%.  This is because the multibyte mask-and-compare
+    // skipping in quickcheck is more likely to do well on this case.
+    bool in_quickcheck_range =
+        ((i - remembered_from < 4) ||
+         (compiler_->one_byte() ? remembered_from <= 4 : remembered_from <= 2));
+    // Called 'probability' but it is only a rough estimate and can actually
+    // be outside the 0-kSize range.
+    int probability = (in_quickcheck_range ? kSize / 2 : kSize) - frequency;
+    int points = (i - remembered_from) * probability;
+    if (points > biggest_points) {
+      *from = remembered_from;
+      *to = i - 1;
+      biggest_points = points;
+    }
+  }
+  return biggest_points;
+}
+
+// Take all the characters that will not prevent a successful match if they
+// occur in the subject string in the range between min_lookahead and
+// max_lookahead (inclusive) measured from the current position.  If the
+// character at max_lookahead offset is not one of these characters, then we
+// can safely skip forwards by the number of characters in the range.
+int BoyerMooreLookahead::GetSkipTable(int min_lookahead, int max_lookahead,
+                                      Handle<ByteArray> boolean_skip_table) {
+  const int kSkipArrayEntry = 0;
+  const int kDontSkipArrayEntry = 1;
+
+  std::memset(boolean_skip_table->GetDataStartAddress(), kSkipArrayEntry,
+              boolean_skip_table->length());
+
+  for (int i = max_lookahead; i >= min_lookahead; i--) {
+    BoyerMoorePositionInfo::Bitset bitset = bitmaps_->at(i)->raw_bitset();
+
+    // Iterate only over set bits.
+    int j;
+    while ((j = BitsetFirstSetBit(bitset)) != -1) {
+      DCHECK(bitset[j]);  // Sanity check.
+      boolean_skip_table->set(j, kDontSkipArrayEntry);
+      bitset.reset(j);
+    }
+  }
+
+  const int skip = max_lookahead + 1 - min_lookahead;
+  return skip;
+}
+
+// See comment above on the implementation of GetSkipTable.
+void BoyerMooreLookahead::EmitSkipInstructions(RegExpMacroAssembler* masm) {
+  const int kSize = RegExpMacroAssembler::kTableSize;
+
+  int min_lookahead = 0;
+  int max_lookahead = 0;
+
+  if (!FindWorthwhileInterval(&min_lookahead, &max_lookahead)) return;
+
+  // Check if we only have a single non-empty position info, and that info
+  // contains precisely one character.
+  bool found_single_character = false;
+  int single_character = 0;
+  for (int i = max_lookahead; i >= min_lookahead; i--) {
+    BoyerMoorePositionInfo* map = bitmaps_->at(i);
+    if (map->map_count() == 0) continue;
+
+    if (found_single_character || map->map_count() > 1) {
+      found_single_character = false;
+      break;
+    }
+
+    DCHECK(!found_single_character);
+    DCHECK_EQ(map->map_count(), 1);
+
+    found_single_character = true;
+    single_character = BitsetFirstSetBit(map->raw_bitset());
+
+    DCHECK_NE(single_character, -1);
+  }
+
+  int lookahead_width = max_lookahead + 1 - min_lookahead;
+
+  if (found_single_character && lookahead_width == 1 && max_lookahead < 3) {
+    // The mask-compare can probably handle this better.
+    return;
+  }
+
+  if (found_single_character) {
+    Label cont, again;
+    masm->Bind(&again);
+    masm->LoadCurrentCharacter(max_lookahead, &cont, true);
+    if (max_char_ > kSize) {
+      masm->CheckCharacterAfterAnd(single_character,
+                                   RegExpMacroAssembler::kTableMask, &cont);
+    } else {
+      masm->CheckCharacter(single_character, &cont);
+    }
+    masm->AdvanceCurrentPosition(lookahead_width);
+    masm->GoTo(&again);
+    masm->Bind(&cont);
+    return;
+  }
+
+  Factory* factory = masm->isolate()->factory();
+  Handle<ByteArray> boolean_skip_table =
+      factory->NewByteArray(kSize, AllocationType::kOld);
+  int skip_distance =
+      GetSkipTable(min_lookahead, max_lookahead, boolean_skip_table);
+  DCHECK_NE(0, skip_distance);
+
+  Label cont, again;
+  masm->Bind(&again);
+  masm->LoadCurrentCharacter(max_lookahead, &cont, true);
+  masm->CheckBitInTable(boolean_skip_table, &cont);
+  masm->AdvanceCurrentPosition(skip_distance);
+  masm->GoTo(&again);
+  masm->Bind(&cont);
+}
+
+/* Code generation for choice nodes.
+ *
+ * We generate quick checks that do a mask and compare to eliminate a
+ * choice.  If the quick check succeeds then it jumps to the continuation to
+ * do slow checks and check subsequent nodes.  If it fails (the common case)
+ * it falls through to the next choice.
+ *
+ * Here is the desired flow graph.  Nodes directly below each other imply
+ * fallthrough.  Alternatives 1 and 2 have quick checks.  Alternative
+ * 3 doesn't have a quick check so we have to call the slow check.
+ * Nodes are marked Qn for quick checks and Sn for slow checks.  The entire
+ * regexp continuation is generated directly after the Sn node, up to the
+ * next GoTo if we decide to reuse some already generated code.  Some
+ * nodes expect preload_characters to be preloaded into the current
+ * character register.  R nodes do this preloading.  Vertices are marked
+ * F for failures and S for success (possible success in the case of quick
+ * nodes).  L, V, < and > are used as arrow heads.
+ *
+ * ----------> R
+ *             |
+ *             V
+ *            Q1 -----> S1
+ *             |   S   /
+ *            F|      /
+ *             |    F/
+ *             |    /
+ *             |   R
+ *             |  /
+ *             V L
+ *            Q2 -----> S2
+ *             |   S   /
+ *            F|      /
+ *             |    F/
+ *             |    /
+ *             |   R
+ *             |  /
+ *             V L
+ *            S3
+ *             |
+ *            F|
+ *             |
+ *             R
+ *             |
+ * backtrack   V
+ * <----------Q4
+ *   \    F    |
+ *    \        |S
+ *     \   F   V
+ *      \-----S4
+ *
+ * For greedy loops we push the current position, then generate the code that
+ * eats the input specially in EmitGreedyLoop.  The other choice (the
+ * continuation) is generated by the normal code in EmitChoices, and steps back
+ * in the input to the starting position when it fails to match.  The loop code
+ * looks like this (U is the unwind code that steps back in the greedy loop).
+ *
+ *              _____
+ *             /     \
+ *             V     |
+ * ----------> S1    |
+ *            /|     |
+ *           / |S    |
+ *         F/  \_____/
+ *         /
+ *        |<-----
+ *        |      \
+ *        V       |S
+ *        Q2 ---> U----->backtrack
+ *        |  F   /
+ *       S|     /
+ *        V  F /
+ *        S2--/
+ */
+
+GreedyLoopState::GreedyLoopState(bool not_at_start) {
+  counter_backtrack_trace_.set_backtrack(&label_);
+  if (not_at_start) counter_backtrack_trace_.set_at_start(Trace::FALSE_VALUE);
+}
+
+void ChoiceNode::AssertGuardsMentionRegisters(Trace* trace) {
+#ifdef DEBUG
+  int choice_count = alternatives_->length();
+  for (int i = 0; i < choice_count - 1; i++) {
+    GuardedAlternative alternative = alternatives_->at(i);
+    ZoneList<Guard*>* guards = alternative.guards();
+    int guard_count = (guards == nullptr) ? 0 : guards->length();
+    for (int j = 0; j < guard_count; j++) {
+      DCHECK(!trace->mentions_reg(guards->at(j)->reg()));
+    }
+  }
+#endif
+}
+
+void ChoiceNode::SetUpPreLoad(RegExpCompiler* compiler, Trace* current_trace,
+                              PreloadState* state) {
+  if (state->eats_at_least_ == PreloadState::kEatsAtLeastNotYetInitialized) {
+    // Save some time by looking at most one machine word ahead.
+    state->eats_at_least_ =
+        EatsAtLeast(current_trace->at_start() == Trace::FALSE_VALUE);
+  }
+  state->preload_characters_ =
+      CalculatePreloadCharacters(compiler, state->eats_at_least_);
+
+  state->preload_is_current_ =
+      (current_trace->characters_preloaded() == state->preload_characters_);
+  state->preload_has_checked_bounds_ = state->preload_is_current_;
+}
+
+void ChoiceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  int choice_count = alternatives_->length();
+
+  if (choice_count == 1 && alternatives_->at(0).guards() == nullptr) {
+    alternatives_->at(0).node()->Emit(compiler, trace);
+    return;
+  }
+
+  AssertGuardsMentionRegisters(trace);
+
+  LimitResult limit_result = LimitVersions(compiler, trace);
+  if (limit_result == DONE) return;
+  DCHECK(limit_result == CONTINUE);
+
+  // For loop nodes we already flushed (see LoopChoiceNode::Emit), but for
+  // other choice nodes we only flush if we are out of code size budget.
+  if (trace->flush_budget() == 0 && trace->actions() != nullptr) {
+    trace->Flush(compiler, this);
+    return;
+  }
+
+  RecursionCheck rc(compiler);
+
+  PreloadState preload;
+  preload.init();
+  GreedyLoopState greedy_loop_state(not_at_start());
+
+  int text_length = GreedyLoopTextLengthForAlternative(&alternatives_->at(0));
+  AlternativeGenerationList alt_gens(choice_count, zone());
+
+  if (choice_count > 1 && text_length != kNodeIsTooComplexForGreedyLoops) {
+    trace = EmitGreedyLoop(compiler, trace, &alt_gens, &preload,
+                           &greedy_loop_state, text_length);
+  } else {
+    // TODO(erikcorry): Delete this.  We don't need this label, but it makes us
+    // match the traces produced pre-cleanup.
+    Label second_choice;
+    compiler->macro_assembler()->Bind(&second_choice);
+
+    preload.eats_at_least_ = EmitOptimizedUnanchoredSearch(compiler, trace);
+
+    EmitChoices(compiler, &alt_gens, 0, trace, &preload);
+  }
+
+  // At this point we need to generate slow checks for the alternatives where
+  // the quick check was inlined.  We can recognize these because the associated
+  // label was bound.
+  int new_flush_budget = trace->flush_budget() / choice_count;
+  for (int i = 0; i < choice_count; i++) {
+    AlternativeGeneration* alt_gen = alt_gens.at(i);
+    Trace new_trace(*trace);
+    // If there are actions to be flushed we have to limit how many times
+    // they are flushed.  Take the budget of the parent trace and distribute
+    // it fairly amongst the children.
+    if (new_trace.actions() != nullptr) {
+      new_trace.set_flush_budget(new_flush_budget);
+    }
+    bool next_expects_preload =
+        i == choice_count - 1 ? false : alt_gens.at(i + 1)->expects_preload;
+    EmitOutOfLineContinuation(compiler, &new_trace, alternatives_->at(i),
+                              alt_gen, preload.preload_characters_,
+                              next_expects_preload);
+  }
+}
+
+Trace* ChoiceNode::EmitGreedyLoop(RegExpCompiler* compiler, Trace* trace,
+                                  AlternativeGenerationList* alt_gens,
+                                  PreloadState* preload,
+                                  GreedyLoopState* greedy_loop_state,
+                                  int text_length) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  // Here we have special handling for greedy loops containing only text nodes
+  // and other simple nodes.  These are handled by pushing the current
+  // position on the stack and then incrementing the current position each
+  // time around the switch.  On backtrack we decrement the current position
+  // and check it against the pushed value.  This avoids pushing backtrack
+  // information for each iteration of the loop, which could take up a lot of
+  // space.
+  DCHECK(trace->stop_node() == nullptr);
+  macro_assembler->PushCurrentPosition();
+  Label greedy_match_failed;
+  Trace greedy_match_trace;
+  if (not_at_start()) greedy_match_trace.set_at_start(Trace::FALSE_VALUE);
+  greedy_match_trace.set_backtrack(&greedy_match_failed);
+  Label loop_label;
+  macro_assembler->Bind(&loop_label);
+  greedy_match_trace.set_stop_node(this);
+  greedy_match_trace.set_loop_label(&loop_label);
+  alternatives_->at(0).node()->Emit(compiler, &greedy_match_trace);
+  macro_assembler->Bind(&greedy_match_failed);
+
+  Label second_choice;  // For use in greedy matches.
+  macro_assembler->Bind(&second_choice);
+
+  Trace* new_trace = greedy_loop_state->counter_backtrack_trace();
+
+  EmitChoices(compiler, alt_gens, 1, new_trace, preload);
+
+  macro_assembler->Bind(greedy_loop_state->label());
+  // If we have unwound to the bottom then backtrack.
+  macro_assembler->CheckGreedyLoop(trace->backtrack());
+  // Otherwise try the second priority at an earlier position.
+  macro_assembler->AdvanceCurrentPosition(-text_length);
+  macro_assembler->GoTo(&second_choice);
+  return new_trace;
+}
+
+int ChoiceNode::EmitOptimizedUnanchoredSearch(RegExpCompiler* compiler,
+                                              Trace* trace) {
+  int eats_at_least = PreloadState::kEatsAtLeastNotYetInitialized;
+  if (alternatives_->length() != 2) return eats_at_least;
+
+  GuardedAlternative alt1 = alternatives_->at(1);
+  if (alt1.guards() != nullptr && alt1.guards()->length() != 0) {
+    return eats_at_least;
+  }
+  RegExpNode* eats_anything_node = alt1.node();
+  if (eats_anything_node->GetSuccessorOfOmnivorousTextNode(compiler) != this) {
+    return eats_at_least;
+  }
+
+  // Really we should be creating a new trace when we execute this function,
+  // but there is no need, because the code it generates cannot backtrack, and
+  // we always arrive here with a trivial trace (since it's the entry to a
+  // loop.  That also implies that there are no preloaded characters, which is
+  // good, because it means we won't be violating any assumptions by
+  // overwriting those characters with new load instructions.
+  DCHECK(trace->is_trivial());
+
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  Isolate* isolate = macro_assembler->isolate();
+  // At this point we know that we are at a non-greedy loop that will eat
+  // any character one at a time.  Any non-anchored regexp has such a
+  // loop prepended to it in order to find where it starts.  We look for
+  // a pattern of the form ...abc... where we can look 6 characters ahead
+  // and step forwards 3 if the character is not one of abc.  Abc need
+  // not be atoms, they can be any reasonably limited character class or
+  // small alternation.
+  BoyerMooreLookahead* bm = bm_info(false);
+  if (bm == nullptr) {
+    eats_at_least = Min(kMaxLookaheadForBoyerMoore, EatsAtLeast(false));
+    if (eats_at_least >= 1) {
+      bm = new (zone()) BoyerMooreLookahead(eats_at_least, compiler, zone());
+      GuardedAlternative alt0 = alternatives_->at(0);
+      alt0.node()->FillInBMInfo(isolate, 0, kRecursionBudget, bm, false);
+    }
+  }
+  if (bm != nullptr) {
+    bm->EmitSkipInstructions(macro_assembler);
+  }
+  return eats_at_least;
+}
+
+void ChoiceNode::EmitChoices(RegExpCompiler* compiler,
+                             AlternativeGenerationList* alt_gens,
+                             int first_choice, Trace* trace,
+                             PreloadState* preload) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  SetUpPreLoad(compiler, trace, preload);
+
+  // For now we just call all choices one after the other.  The idea ultimately
+  // is to use the Dispatch table to try only the relevant ones.
+  int choice_count = alternatives_->length();
+
+  int new_flush_budget = trace->flush_budget() / choice_count;
+
+  for (int i = first_choice; i < choice_count; i++) {
+    bool is_last = i == choice_count - 1;
+    bool fall_through_on_failure = !is_last;
+    GuardedAlternative alternative = alternatives_->at(i);
+    AlternativeGeneration* alt_gen = alt_gens->at(i);
+    alt_gen->quick_check_details.set_characters(preload->preload_characters_);
+    ZoneList<Guard*>* guards = alternative.guards();
+    int guard_count = (guards == nullptr) ? 0 : guards->length();
+    Trace new_trace(*trace);
+    new_trace.set_characters_preloaded(
+        preload->preload_is_current_ ? preload->preload_characters_ : 0);
+    if (preload->preload_has_checked_bounds_) {
+      new_trace.set_bound_checked_up_to(preload->preload_characters_);
+    }
+    new_trace.quick_check_performed()->Clear();
+    if (not_at_start_) new_trace.set_at_start(Trace::FALSE_VALUE);
+    if (!is_last) {
+      new_trace.set_backtrack(&alt_gen->after);
+    }
+    alt_gen->expects_preload = preload->preload_is_current_;
+    bool generate_full_check_inline = false;
+    if (compiler->optimize() &&
+        try_to_emit_quick_check_for_alternative(i == 0) &&
+        alternative.node()->EmitQuickCheck(
+            compiler, trace, &new_trace, preload->preload_has_checked_bounds_,
+            &alt_gen->possible_success, &alt_gen->quick_check_details,
+            fall_through_on_failure, this)) {
+      // Quick check was generated for this choice.
+      preload->preload_is_current_ = true;
+      preload->preload_has_checked_bounds_ = true;
+      // If we generated the quick check to fall through on possible success,
+      // we now need to generate the full check inline.
+      if (!fall_through_on_failure) {
+        macro_assembler->Bind(&alt_gen->possible_success);
+        new_trace.set_quick_check_performed(&alt_gen->quick_check_details);
+        new_trace.set_characters_preloaded(preload->preload_characters_);
+        new_trace.set_bound_checked_up_to(preload->preload_characters_);
+        generate_full_check_inline = true;
+      }
+    } else if (alt_gen->quick_check_details.cannot_match()) {
+      if (!fall_through_on_failure) {
+        macro_assembler->GoTo(trace->backtrack());
+      }
+      continue;
+    } else {
+      // No quick check was generated.  Put the full code here.
+      // If this is not the first choice then there could be slow checks from
+      // previous cases that go here when they fail.  There's no reason to
+      // insist that they preload characters since the slow check we are about
+      // to generate probably can't use it.
+      if (i != first_choice) {
+        alt_gen->expects_preload = false;
+        new_trace.InvalidateCurrentCharacter();
+      }
+      generate_full_check_inline = true;
+    }
+    if (generate_full_check_inline) {
+      if (new_trace.actions() != nullptr) {
+        new_trace.set_flush_budget(new_flush_budget);
+      }
+      for (int j = 0; j < guard_count; j++) {
+        GenerateGuard(macro_assembler, guards->at(j), &new_trace);
+      }
+      alternative.node()->Emit(compiler, &new_trace);
+      preload->preload_is_current_ = false;
+    }
+    macro_assembler->Bind(&alt_gen->after);
+  }
+}
+
+void ChoiceNode::EmitOutOfLineContinuation(RegExpCompiler* compiler,
+                                           Trace* trace,
+                                           GuardedAlternative alternative,
+                                           AlternativeGeneration* alt_gen,
+                                           int preload_characters,
+                                           bool next_expects_preload) {
+  if (!alt_gen->possible_success.is_linked()) return;
+
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  macro_assembler->Bind(&alt_gen->possible_success);
+  Trace out_of_line_trace(*trace);
+  out_of_line_trace.set_characters_preloaded(preload_characters);
+  out_of_line_trace.set_quick_check_performed(&alt_gen->quick_check_details);
+  if (not_at_start_) out_of_line_trace.set_at_start(Trace::FALSE_VALUE);
+  ZoneList<Guard*>* guards = alternative.guards();
+  int guard_count = (guards == nullptr) ? 0 : guards->length();
+  if (next_expects_preload) {
+    Label reload_current_char;
+    out_of_line_trace.set_backtrack(&reload_current_char);
+    for (int j = 0; j < guard_count; j++) {
+      GenerateGuard(macro_assembler, guards->at(j), &out_of_line_trace);
+    }
+    alternative.node()->Emit(compiler, &out_of_line_trace);
+    macro_assembler->Bind(&reload_current_char);
+    // Reload the current character, since the next quick check expects that.
+    // We don't need to check bounds here because we only get into this
+    // code through a quick check which already did the checked load.
+    macro_assembler->LoadCurrentCharacter(trace->cp_offset(), nullptr, false,
+                                          preload_characters);
+    macro_assembler->GoTo(&(alt_gen->after));
+  } else {
+    out_of_line_trace.set_backtrack(&(alt_gen->after));
+    for (int j = 0; j < guard_count; j++) {
+      GenerateGuard(macro_assembler, guards->at(j), &out_of_line_trace);
+    }
+    alternative.node()->Emit(compiler, &out_of_line_trace);
+  }
+}
+
+void ActionNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  LimitResult limit_result = LimitVersions(compiler, trace);
+  if (limit_result == DONE) return;
+  DCHECK(limit_result == CONTINUE);
+
+  RecursionCheck rc(compiler);
+
+  switch (action_type_) {
+    case STORE_POSITION: {
+      Trace::DeferredCapture new_capture(data_.u_position_register.reg,
+                                         data_.u_position_register.is_capture,
+                                         trace);
+      Trace new_trace = *trace;
+      new_trace.add_action(&new_capture);
+      on_success()->Emit(compiler, &new_trace);
+      break;
+    }
+    case INCREMENT_REGISTER: {
+      Trace::DeferredIncrementRegister new_increment(
+          data_.u_increment_register.reg);
+      Trace new_trace = *trace;
+      new_trace.add_action(&new_increment);
+      on_success()->Emit(compiler, &new_trace);
+      break;
+    }
+    case SET_REGISTER_FOR_LOOP: {
+      Trace::DeferredSetRegisterForLoop new_set(data_.u_store_register.reg,
+                                                data_.u_store_register.value);
+      Trace new_trace = *trace;
+      new_trace.add_action(&new_set);
+      on_success()->Emit(compiler, &new_trace);
+      break;
+    }
+    case CLEAR_CAPTURES: {
+      Trace::DeferredClearCaptures new_capture(Interval(
+          data_.u_clear_captures.range_from, data_.u_clear_captures.range_to));
+      Trace new_trace = *trace;
+      new_trace.add_action(&new_capture);
+      on_success()->Emit(compiler, &new_trace);
+      break;
+    }
+    case BEGIN_SUBMATCH:
+      if (!trace->is_trivial()) {
+        trace->Flush(compiler, this);
+      } else {
+        assembler->WriteCurrentPositionToRegister(
+            data_.u_submatch.current_position_register, 0);
+        assembler->WriteStackPointerToRegister(
+            data_.u_submatch.stack_pointer_register);
+        on_success()->Emit(compiler, trace);
+      }
+      break;
+    case EMPTY_MATCH_CHECK: {
+      int start_pos_reg = data_.u_empty_match_check.start_register;
+      int stored_pos = 0;
+      int rep_reg = data_.u_empty_match_check.repetition_register;
+      bool has_minimum = (rep_reg != RegExpCompiler::kNoRegister);
+      bool know_dist = trace->GetStoredPosition(start_pos_reg, &stored_pos);
+      if (know_dist && !has_minimum && stored_pos == trace->cp_offset()) {
+        // If we know we haven't advanced and there is no minimum we
+        // can just backtrack immediately.
+        assembler->GoTo(trace->backtrack());
+      } else if (know_dist && stored_pos < trace->cp_offset()) {
+        // If we know we've advanced we can generate the continuation
+        // immediately.
+        on_success()->Emit(compiler, trace);
+      } else if (!trace->is_trivial()) {
+        trace->Flush(compiler, this);
+      } else {
+        Label skip_empty_check;
+        // If we have a minimum number of repetitions we check the current
+        // number first and skip the empty check if it's not enough.
+        if (has_minimum) {
+          int limit = data_.u_empty_match_check.repetition_limit;
+          assembler->IfRegisterLT(rep_reg, limit, &skip_empty_check);
+        }
+        // If the match is empty we bail out, otherwise we fall through
+        // to the on-success continuation.
+        assembler->IfRegisterEqPos(data_.u_empty_match_check.start_register,
+                                   trace->backtrack());
+        assembler->Bind(&skip_empty_check);
+        on_success()->Emit(compiler, trace);
+      }
+      break;
+    }
+    case POSITIVE_SUBMATCH_SUCCESS: {
+      if (!trace->is_trivial()) {
+        trace->Flush(compiler, this);
+        return;
+      }
+      assembler->ReadCurrentPositionFromRegister(
+          data_.u_submatch.current_position_register);
+      assembler->ReadStackPointerFromRegister(
+          data_.u_submatch.stack_pointer_register);
+      int clear_register_count = data_.u_submatch.clear_register_count;
+      if (clear_register_count == 0) {
+        on_success()->Emit(compiler, trace);
+        return;
+      }
+      int clear_registers_from = data_.u_submatch.clear_register_from;
+      Label clear_registers_backtrack;
+      Trace new_trace = *trace;
+      new_trace.set_backtrack(&clear_registers_backtrack);
+      on_success()->Emit(compiler, &new_trace);
+
+      assembler->Bind(&clear_registers_backtrack);
+      int clear_registers_to = clear_registers_from + clear_register_count - 1;
+      assembler->ClearRegisters(clear_registers_from, clear_registers_to);
+
+      DCHECK(trace->backtrack() == nullptr);
+      assembler->Backtrack();
+      return;
+    }
+    default:
+      UNREACHABLE();
+  }
+}
+
+void BackReferenceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  if (!trace->is_trivial()) {
+    trace->Flush(compiler, this);
+    return;
+  }
+
+  LimitResult limit_result = LimitVersions(compiler, trace);
+  if (limit_result == DONE) return;
+  DCHECK(limit_result == CONTINUE);
+
+  RecursionCheck rc(compiler);
+
+  DCHECK_EQ(start_reg_ + 1, end_reg_);
+  if (IgnoreCase(flags_)) {
+    assembler->CheckNotBackReferenceIgnoreCase(
+        start_reg_, read_backward(), IsUnicode(flags_), trace->backtrack());
+  } else {
+    assembler->CheckNotBackReference(start_reg_, read_backward(),
+                                     trace->backtrack());
+  }
+  // We are going to advance backward, so we may end up at the start.
+  if (read_backward()) trace->set_at_start(Trace::UNKNOWN);
+
+  // Check that the back reference does not end inside a surrogate pair.
+  if (IsUnicode(flags_) && !compiler->one_byte()) {
+    assembler->CheckNotInSurrogatePair(trace->cp_offset(), trace->backtrack());
+  }
+  on_success()->Emit(compiler, trace);
+}
+
+void TextNode::CalculateOffsets() {
+  int element_count = elements()->length();
+  // Set up the offsets of the elements relative to the start.  This is a fixed
+  // quantity since a TextNode can only contain fixed-width things.
+  int cp_offset = 0;
+  for (int i = 0; i < element_count; i++) {
+    TextElement& elm = elements()->at(i);
+    elm.set_cp_offset(cp_offset);
+    cp_offset += elm.length();
+  }
+}
+
+namespace {
+
+// Assertion propagation moves information about assertions such as
+// \b to the affected nodes.  For instance, in /.\b./ information must
+// be propagated to the first '.' that whatever follows needs to know
+// if it matched a word or a non-word, and to the second '.' that it
+// has to check if it succeeds a word or non-word.  In this case the
+// result will be something like:
+//
+//   +-------+        +------------+
+//   |   .   |        |      .     |
+//   +-------+  --->  +------------+
+//   | word? |        | check word |
+//   +-------+        +------------+
+class AssertionPropagator : public AllStatic {
+ public:
+  static void VisitText(TextNode* that) {}
+
+  static void VisitAction(ActionNode* that) {
+    // If the next node is interested in what it follows then this node
+    // has to be interested too so it can pass the information on.
+    that->info()->AddFromFollowing(that->on_success()->info());
+  }
+
+  static void VisitChoice(ChoiceNode* that, int i) {
+    // Anything the following nodes need to know has to be known by
+    // this node also, so it can pass it on.
+    that->info()->AddFromFollowing(that->alternatives()->at(i).node()->info());
+  }
+
+  static void VisitLoopChoiceContinueNode(LoopChoiceNode* that) {
+    that->info()->AddFromFollowing(that->continue_node()->info());
+  }
+
+  static void VisitLoopChoiceLoopNode(LoopChoiceNode* that) {
+    that->info()->AddFromFollowing(that->loop_node()->info());
+  }
+
+  static void VisitNegativeLookaroundChoiceLookaroundNode(
+      NegativeLookaroundChoiceNode* that) {
+    VisitChoice(that, NegativeLookaroundChoiceNode::kLookaroundIndex);
+  }
+
+  static void VisitNegativeLookaroundChoiceContinueNode(
+      NegativeLookaroundChoiceNode* that) {
+    VisitChoice(that, NegativeLookaroundChoiceNode::kContinueIndex);
+  }
+
+  static void VisitBackReference(BackReferenceNode* that) {}
+
+  static void VisitAssertion(AssertionNode* that) {}
+};
+
+// Propagates information about the minimum size of successful matches from
+// successor nodes to their predecessors. Note that all eats_at_least values
+// are initialized to zero before analysis.
+class EatsAtLeastPropagator : public AllStatic {
+ public:
+  static void VisitText(TextNode* that) {
+    // The eats_at_least value is not used if reading backward.
+    if (!that->read_backward()) {
+      // We are not at the start after this node, and thus we can use the
+      // successor's eats_at_least_from_not_start value.
+      uint8_t eats_at_least = base::saturated_cast<uint8_t>(
+          that->Length() + that->on_success()
+                               ->eats_at_least_info()
+                               ->eats_at_least_from_not_start);
+      that->set_eats_at_least_info(EatsAtLeastInfo(eats_at_least));
+    }
+  }
+
+  static void VisitAction(ActionNode* that) {
+    // POSITIVE_SUBMATCH_SUCCESS rewinds input, so we must not consider
+    // successor nodes for eats_at_least. SET_REGISTER_FOR_LOOP indicates a loop
+    // entry point, which means the loop body will run at least the minimum
+    // number of times before the continuation case can run. Otherwise the
+    // current node eats at least as much as its successor.
+    switch (that->action_type()) {
+      case ActionNode::POSITIVE_SUBMATCH_SUCCESS:
+        break;  // Was already initialized to zero.
+      case ActionNode::SET_REGISTER_FOR_LOOP:
+        that->set_eats_at_least_info(
+            that->on_success()->EatsAtLeastFromLoopEntry());
+        break;
+      default:
+        that->set_eats_at_least_info(*that->on_success()->eats_at_least_info());
+        break;
+    }
+  }
+
+  static void VisitChoice(ChoiceNode* that, int i) {
+    // The minimum possible match from a choice node is the minimum of its
+    // successors.
+    EatsAtLeastInfo eats_at_least =
+        i == 0 ? EatsAtLeastInfo(UINT8_MAX) : *that->eats_at_least_info();
+    eats_at_least.SetMin(
+        *that->alternatives()->at(i).node()->eats_at_least_info());
+    that->set_eats_at_least_info(eats_at_least);
+  }
+
+  static void VisitLoopChoiceContinueNode(LoopChoiceNode* that) {
+    that->set_eats_at_least_info(*that->continue_node()->eats_at_least_info());
+  }
+
+  static void VisitLoopChoiceLoopNode(LoopChoiceNode* that) {}
+
+  static void VisitNegativeLookaroundChoiceLookaroundNode(
+      NegativeLookaroundChoiceNode* that) {}
+
+  static void VisitNegativeLookaroundChoiceContinueNode(
+      NegativeLookaroundChoiceNode* that) {
+    that->set_eats_at_least_info(*that->continue_node()->eats_at_least_info());
+  }
+
+  static void VisitBackReference(BackReferenceNode* that) {
+    if (!that->read_backward()) {
+      that->set_eats_at_least_info(*that->on_success()->eats_at_least_info());
+    }
+  }
+
+  static void VisitAssertion(AssertionNode* that) {
+    EatsAtLeastInfo eats_at_least = *that->on_success()->eats_at_least_info();
+    if (that->assertion_type() == AssertionNode::AT_START) {
+      // If we know we are not at the start and we are asked "how many
+      // characters will you match if you succeed?" then we can answer anything
+      // since false implies false.  So let's just set the max answer
+      // (UINT8_MAX) since that won't prevent us from preloading a lot of
+      // characters for the other branches in the node graph.
+      eats_at_least.eats_at_least_from_not_start = UINT8_MAX;
+    }
+    that->set_eats_at_least_info(eats_at_least);
+  }
+};
+
+}  // namespace
+
+// -------------------------------------------------------------------
+// Analysis
+
+// Iterates the node graph and provides the opportunity for propagators to set
+// values that depend on successor nodes.
+template <typename... Propagators>
+class Analysis : public NodeVisitor {
+ public:
+  Analysis(Isolate* isolate, bool is_one_byte)
+      : isolate_(isolate), is_one_byte_(is_one_byte), error_message_(nullptr) {}
+
+  void EnsureAnalyzed(RegExpNode* that) {
+    StackLimitCheck check(isolate());
+    if (check.HasOverflowed()) {
+      fail("Stack overflow");
+      return;
+    }
+    if (that->info()->been_analyzed || that->info()->being_analyzed) return;
+    that->info()->being_analyzed = true;
+    that->Accept(this);
+    that->info()->being_analyzed = false;
+    that->info()->been_analyzed = true;
+  }
+
+  bool has_failed() { return error_message_ != nullptr; }
+  const char* error_message() {
+    DCHECK(error_message_ != nullptr);
+    return error_message_;
+  }
+  void fail(const char* error_message) { error_message_ = error_message; }
+
+  Isolate* isolate() const { return isolate_; }
+
+  void VisitEnd(EndNode* that) override {
+    // nothing to do
+  }
+
+// Used to call the given static function on each propagator / variadic template
+// argument.
+#define STATIC_FOR_EACH(expr)       \
+  do {                              \
+    int dummy[] = {((expr), 0)...}; \
+    USE(dummy);                     \
+  } while (false)
+
+  void VisitText(TextNode* that) override {
+    that->MakeCaseIndependent(isolate(), is_one_byte_);
+    EnsureAnalyzed(that->on_success());
+    if (has_failed()) return;
+    that->CalculateOffsets();
+    STATIC_FOR_EACH(Propagators::VisitText(that));
+  }
+
+  void VisitAction(ActionNode* that) override {
+    EnsureAnalyzed(that->on_success());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitAction(that));
+  }
+
+  void VisitChoice(ChoiceNode* that) override {
+    for (int i = 0; i < that->alternatives()->length(); i++) {
+      EnsureAnalyzed(that->alternatives()->at(i).node());
+      if (has_failed()) return;
+      STATIC_FOR_EACH(Propagators::VisitChoice(that, i));
+    }
+  }
+
+  void VisitLoopChoice(LoopChoiceNode* that) override {
+    DCHECK_EQ(that->alternatives()->length(), 2);  // Just loop and continue.
+
+    // First propagate all information from the continuation node.
+    EnsureAnalyzed(that->continue_node());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitLoopChoiceContinueNode(that));
+
+    // Check the loop last since it may need the value of this node
+    // to get a correct result.
+    EnsureAnalyzed(that->loop_node());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitLoopChoiceLoopNode(that));
+  }
+
+  void VisitNegativeLookaroundChoice(
+      NegativeLookaroundChoiceNode* that) override {
+    DCHECK_EQ(that->alternatives()->length(), 2);  // Lookaround and continue.
+
+    EnsureAnalyzed(that->lookaround_node());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(
+        Propagators::VisitNegativeLookaroundChoiceLookaroundNode(that));
+
+    EnsureAnalyzed(that->continue_node());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(
+        Propagators::VisitNegativeLookaroundChoiceContinueNode(that));
+  }
+
+  void VisitBackReference(BackReferenceNode* that) override {
+    EnsureAnalyzed(that->on_success());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitBackReference(that));
+  }
+
+  void VisitAssertion(AssertionNode* that) override {
+    EnsureAnalyzed(that->on_success());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitAssertion(that));
+  }
+
+#undef STATIC_FOR_EACH
+
+ private:
+  Isolate* isolate_;
+  bool is_one_byte_;
+  const char* error_message_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Analysis);
+};
+
+const char* AnalyzeRegExp(Isolate* isolate, bool is_one_byte,
+                          RegExpNode* node) {
+  Analysis<AssertionPropagator, EatsAtLeastPropagator> analysis(isolate,
+                                                                is_one_byte);
+  DCHECK_EQ(node->info()->been_analyzed, false);
+  analysis.EnsureAnalyzed(node);
+  DCHECK_IMPLIES(analysis.has_failed(), analysis.error_message() != nullptr);
+  return analysis.has_failed() ? analysis.error_message() : nullptr;
+}
+
+void BackReferenceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                                     BoyerMooreLookahead* bm,
+                                     bool not_at_start) {
+  // Working out the set of characters that a backreference can match is too
+  // hard, so we just say that any character can match.
+  bm->SetRest(offset);
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+STATIC_ASSERT(BoyerMoorePositionInfo::kMapSize ==
+              RegExpMacroAssembler::kTableSize);
+
+void ChoiceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                              BoyerMooreLookahead* bm, bool not_at_start) {
+  ZoneList<GuardedAlternative>* alts = alternatives();
+  budget = (budget - 1) / alts->length();
+  for (int i = 0; i < alts->length(); i++) {
+    GuardedAlternative& alt = alts->at(i);
+    if (alt.guards() != nullptr && alt.guards()->length() != 0) {
+      bm->SetRest(offset);  // Give up trying to fill in info.
+      SaveBMInfo(bm, not_at_start, offset);
+      return;
+    }
+    alt.node()->FillInBMInfo(isolate, offset, budget, bm, not_at_start);
+  }
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+void TextNode::FillInBMInfo(Isolate* isolate, int initial_offset, int budget,
+                            BoyerMooreLookahead* bm, bool not_at_start) {
+  if (initial_offset >= bm->length()) return;
+  int offset = initial_offset;
+  int max_char = bm->max_char();
+  for (int i = 0; i < elements()->length(); i++) {
+    if (offset >= bm->length()) {
+      if (initial_offset == 0) set_bm_info(not_at_start, bm);
+      return;
+    }
+    TextElement text = elements()->at(i);
+    if (text.text_type() == TextElement::ATOM) {
+      RegExpAtom* atom = text.atom();
+      for (int j = 0; j < atom->length(); j++, offset++) {
+        if (offset >= bm->length()) {
+          if (initial_offset == 0) set_bm_info(not_at_start, bm);
+          return;
+        }
+        uc16 character = atom->data()[j];
+        if (IgnoreCase(atom->flags())) {
+          unibrow::uchar chars[4];
+          int length = GetCaseIndependentLetters(
+              isolate, character, bm->max_char() == String::kMaxOneByteCharCode,
+              chars, 4);
+          for (int j = 0; j < length; j++) {
+            bm->Set(offset, chars[j]);
+          }
+        } else {
+          if (character <= max_char) bm->Set(offset, character);
+        }
+      }
+    } else {
+      DCHECK_EQ(TextElement::CHAR_CLASS, text.text_type());
+      RegExpCharacterClass* char_class = text.char_class();
+      ZoneList<CharacterRange>* ranges = char_class->ranges(zone());
+      if (char_class->is_negated()) {
+        bm->SetAll(offset);
+      } else {
+        for (int k = 0; k < ranges->length(); k++) {
+          CharacterRange& range = ranges->at(k);
+          if (range.from() > max_char) continue;
+          int to = Min(max_char, static_cast<int>(range.to()));
+          bm->SetInterval(offset, Interval(range.from(), to));
+        }
+      }
+      offset++;
+    }
+  }
+  if (offset >= bm->length()) {
+    if (initial_offset == 0) set_bm_info(not_at_start, bm);
+    return;
+  }
+  on_success()->FillInBMInfo(isolate, offset, budget - 1, bm,
+                             true);  // Not at start after a text node.
+  if (initial_offset == 0) set_bm_info(not_at_start, bm);
+}
+
+// static
+RegExpNode* RegExpCompiler::OptionallyStepBackToLeadSurrogate(
+    RegExpCompiler* compiler, RegExpNode* on_success, JSRegExp::Flags flags) {
+  DCHECK(!compiler->read_backward());
+  Zone* zone = compiler->zone();
+  ZoneList<CharacterRange>* lead_surrogates = CharacterRange::List(
+      zone, CharacterRange::Range(kLeadSurrogateStart, kLeadSurrogateEnd));
+  ZoneList<CharacterRange>* trail_surrogates = CharacterRange::List(
+      zone, CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd));
+
+  ChoiceNode* optional_step_back = new (zone) ChoiceNode(2, zone);
+
+  int stack_register = compiler->UnicodeLookaroundStackRegister();
+  int position_register = compiler->UnicodeLookaroundPositionRegister();
+  RegExpNode* step_back = TextNode::CreateForCharacterRanges(
+      zone, lead_surrogates, true, on_success, flags);
+  RegExpLookaround::Builder builder(true, step_back, stack_register,
+                                    position_register);
+  RegExpNode* match_trail = TextNode::CreateForCharacterRanges(
+      zone, trail_surrogates, false, builder.on_match_success(), flags);
+
+  optional_step_back->AddAlternative(
+      GuardedAlternative(builder.ForMatch(match_trail)));
+  optional_step_back->AddAlternative(GuardedAlternative(on_success));
+
+  return optional_step_back;
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-compiler.h b/js/src/regexp/regexp-compiler.h
new file mode 100644
index 0000000000..192b3284d6
--- /dev/null
+++ b/js/src/regexp/regexp-compiler.h
@@ -0,0 +1,625 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_COMPILER_H_
+#define V8_REGEXP_REGEXP_COMPILER_H_
+
+#include <bitset>
+
+#include "regexp/regexp-nodes.h"
+
+namespace v8 {
+namespace internal {
+
+class DynamicBitSet;
+class Isolate;
+
+namespace regexp_compiler_constants {
+
+// The '2' variant is has inclusive from and exclusive to.
+// This covers \s as defined in ECMA-262 5.1, 15.10.2.12,
+// which include WhiteSpace (7.2) or LineTerminator (7.3) values.
+constexpr uc32 kRangeEndMarker = 0x110000;
+constexpr int kSpaceRanges[] = {
+    '\t',   '\r' + 1, ' ',    ' ' + 1, 0x00A0, 0x00A1, 0x1680,
+    0x1681, 0x2000,   0x200B, 0x2028,  0x202A, 0x202F, 0x2030,
+    0x205F, 0x2060,   0x3000, 0x3001,  0xFEFF, 0xFF00, kRangeEndMarker};
+constexpr int kSpaceRangeCount = arraysize(kSpaceRanges);
+
+constexpr int kWordRanges[] = {'0',     '9' + 1, 'A',     'Z' + 1,        '_',
+                               '_' + 1, 'a',     'z' + 1, kRangeEndMarker};
+constexpr int kWordRangeCount = arraysize(kWordRanges);
+constexpr int kDigitRanges[] = {'0', '9' + 1, kRangeEndMarker};
+constexpr int kDigitRangeCount = arraysize(kDigitRanges);
+constexpr int kSurrogateRanges[] = {kLeadSurrogateStart,
+                                    kLeadSurrogateStart + 1, kRangeEndMarker};
+constexpr int kSurrogateRangeCount = arraysize(kSurrogateRanges);
+constexpr int kLineTerminatorRanges[] = {0x000A, 0x000B, 0x000D,         0x000E,
+                                         0x2028, 0x202A, kRangeEndMarker};
+constexpr int kLineTerminatorRangeCount = arraysize(kLineTerminatorRanges);
+
+// More makes code generation slower, less makes V8 benchmark score lower.
+constexpr int kMaxLookaheadForBoyerMoore = 8;
+// In a 3-character pattern you can maximally step forwards 3 characters
+// at a time, which is not always enough to pay for the extra logic.
+constexpr int kPatternTooShortForBoyerMoore = 2;
+
+}  // namespace regexp_compiler_constants
+
+inline bool IgnoreCase(JSRegExp::Flags flags) {
+  return (flags & JSRegExp::kIgnoreCase) != 0;
+}
+
+inline bool IsUnicode(JSRegExp::Flags flags) {
+  return (flags & JSRegExp::kUnicode) != 0;
+}
+
+inline bool IsSticky(JSRegExp::Flags flags) {
+  return (flags & JSRegExp::kSticky) != 0;
+}
+
+inline bool IsGlobal(JSRegExp::Flags flags) {
+  return (flags & JSRegExp::kGlobal) != 0;
+}
+
+inline bool DotAll(JSRegExp::Flags flags) {
+  return (flags & JSRegExp::kDotAll) != 0;
+}
+
+inline bool Multiline(JSRegExp::Flags flags) {
+  return (flags & JSRegExp::kMultiline) != 0;
+}
+
+inline bool NeedsUnicodeCaseEquivalents(JSRegExp::Flags flags) {
+  // Both unicode and ignore_case flags are set. We need to use ICU to find
+  // the closure over case equivalents.
+  return IsUnicode(flags) && IgnoreCase(flags);
+}
+
+// Details of a quick mask-compare check that can look ahead in the
+// input stream.
+class QuickCheckDetails {
+ public:
+  QuickCheckDetails()
+      : characters_(0), mask_(0), value_(0), cannot_match_(false) {}
+  explicit QuickCheckDetails(int characters)
+      : characters_(characters), mask_(0), value_(0), cannot_match_(false) {}
+  bool Rationalize(bool one_byte);
+  // Merge in the information from another branch of an alternation.
+  void Merge(QuickCheckDetails* other, int from_index);
+  // Advance the current position by some amount.
+  void Advance(int by, bool one_byte);
+  void Clear();
+  bool cannot_match() { return cannot_match_; }
+  void set_cannot_match() { cannot_match_ = true; }
+  struct Position {
+    Position() : mask(0), value(0), determines_perfectly(false) {}
+    uc16 mask;
+    uc16 value;
+    bool determines_perfectly;
+  };
+  int characters() { return characters_; }
+  void set_characters(int characters) { characters_ = characters; }
+  Position* positions(int index) {
+    DCHECK_LE(0, index);
+    DCHECK_GT(characters_, index);
+    return positions_ + index;
+  }
+  uint32_t mask() { return mask_; }
+  uint32_t value() { return value_; }
+
+ private:
+  // How many characters do we have quick check information from.  This is
+  // the same for all branches of a choice node.
+  int characters_;
+  Position positions_[4];
+  // These values are the condensate of the above array after Rationalize().
+  uint32_t mask_;
+  uint32_t value_;
+  // If set to true, there is no way this quick check can match at all.
+  // E.g., if it requires to be at the start of the input, and isn't.
+  bool cannot_match_;
+};
+
+// Improve the speed that we scan for an initial point where a non-anchored
+// regexp can match by using a Boyer-Moore-like table. This is done by
+// identifying non-greedy non-capturing loops in the nodes that eat any
+// character one at a time.  For example in the middle of the regexp
+// /foo[\s\S]*?bar/ we find such a loop.  There is also such a loop implicitly
+// inserted at the start of any non-anchored regexp.
+//
+// When we have found such a loop we look ahead in the nodes to find the set of
+// characters that can come at given distances. For example for the regexp
+// /.?foo/ we know that there are at least 3 characters ahead of us, and the
+// sets of characters that can occur are [any, [f, o], [o]]. We find a range in
+// the lookahead info where the set of characters is reasonably constrained. In
+// our example this is from index 1 to 2 (0 is not constrained). We can now
+// look 3 characters ahead and if we don't find one of [f, o] (the union of
+// [f, o] and [o]) then we can skip forwards by the range size (in this case 2).
+//
+// For Unicode input strings we do the same, but modulo 128.
+//
+// We also look at the first string fed to the regexp and use that to get a hint
+// of the character frequencies in the inputs. This affects the assessment of
+// whether the set of characters is 'reasonably constrained'.
+//
+// We also have another lookahead mechanism (called quick check in the code),
+// which uses a wide load of multiple characters followed by a mask and compare
+// to determine whether a match is possible at this point.
+enum ContainedInLattice {
+  kNotYet = 0,
+  kLatticeIn = 1,
+  kLatticeOut = 2,
+  kLatticeUnknown = 3  // Can also mean both in and out.
+};
+
+inline ContainedInLattice Combine(ContainedInLattice a, ContainedInLattice b) {
+  return static_cast<ContainedInLattice>(a | b);
+}
+
+class BoyerMoorePositionInfo : public ZoneObject {
+ public:
+  bool at(int i) const { return map_[i]; }
+
+  static constexpr int kMapSize = 128;
+  static constexpr int kMask = kMapSize - 1;
+
+  int map_count() const { return map_count_; }
+
+  void Set(int character);
+  void SetInterval(const Interval& interval);
+  void SetAll();
+
+  bool is_non_word() { return w_ == kLatticeOut; }
+  bool is_word() { return w_ == kLatticeIn; }
+
+  using Bitset = std::bitset<kMapSize>;
+  Bitset raw_bitset() const { return map_; }
+
+ private:
+  Bitset map_;
+  int map_count_ = 0;               // Number of set bits in the map.
+  ContainedInLattice w_ = kNotYet;  // The \w character class.
+};
+
+class BoyerMooreLookahead : public ZoneObject {
+ public:
+  BoyerMooreLookahead(int length, RegExpCompiler* compiler, Zone* zone);
+
+  int length() { return length_; }
+  int max_char() { return max_char_; }
+  RegExpCompiler* compiler() { return compiler_; }
+
+  int Count(int map_number) { return bitmaps_->at(map_number)->map_count(); }
+
+  BoyerMoorePositionInfo* at(int i) { return bitmaps_->at(i); }
+
+  void Set(int map_number, int character) {
+    if (character > max_char_) return;
+    BoyerMoorePositionInfo* info = bitmaps_->at(map_number);
+    info->Set(character);
+  }
+
+  void SetInterval(int map_number, const Interval& interval) {
+    if (interval.from() > max_char_) return;
+    BoyerMoorePositionInfo* info = bitmaps_->at(map_number);
+    if (interval.to() > max_char_) {
+      info->SetInterval(Interval(interval.from(), max_char_));
+    } else {
+      info->SetInterval(interval);
+    }
+  }
+
+  void SetAll(int map_number) { bitmaps_->at(map_number)->SetAll(); }
+
+  void SetRest(int from_map) {
+    for (int i = from_map; i < length_; i++) SetAll(i);
+  }
+  void EmitSkipInstructions(RegExpMacroAssembler* masm);
+
+ private:
+  // This is the value obtained by EatsAtLeast.  If we do not have at least this
+  // many characters left in the sample string then the match is bound to fail.
+  // Therefore it is OK to read a character this far ahead of the current match
+  // point.
+  int length_;
+  RegExpCompiler* compiler_;
+  // 0xff for Latin1, 0xffff for UTF-16.
+  int max_char_;
+  ZoneList<BoyerMoorePositionInfo*>* bitmaps_;
+
+  int GetSkipTable(int min_lookahead, int max_lookahead,
+                   Handle<ByteArray> boolean_skip_table);
+  bool FindWorthwhileInterval(int* from, int* to);
+  int FindBestInterval(int max_number_of_chars, int old_biggest_points,
+                       int* from, int* to);
+};
+
+// There are many ways to generate code for a node.  This class encapsulates
+// the current way we should be generating.  In other words it encapsulates
+// the current state of the code generator.  The effect of this is that we
+// generate code for paths that the matcher can take through the regular
+// expression.  A given node in the regexp can be code-generated several times
+// as it can be part of several traces.  For example for the regexp:
+// /foo(bar|ip)baz/ the code to match baz will be generated twice, once as part
+// of the foo-bar-baz trace and once as part of the foo-ip-baz trace.  The code
+// to match foo is generated only once (the traces have a common prefix).  The
+// code to store the capture is deferred and generated (twice) after the places
+// where baz has been matched.
+class Trace {
+ public:
+  // A value for a property that is either known to be true, know to be false,
+  // or not known.
+  enum TriBool { UNKNOWN = -1, FALSE_VALUE = 0, TRUE_VALUE = 1 };
+
+  class DeferredAction {
+   public:
+    DeferredAction(ActionNode::ActionType action_type, int reg)
+        : action_type_(action_type), reg_(reg), next_(nullptr) {}
+    DeferredAction* next() { return next_; }
+    bool Mentions(int reg);
+    int reg() { return reg_; }
+    ActionNode::ActionType action_type() { return action_type_; }
+
+   private:
+    ActionNode::ActionType action_type_;
+    int reg_;
+    DeferredAction* next_;
+    friend class Trace;
+  };
+
+  class DeferredCapture : public DeferredAction {
+   public:
+    DeferredCapture(int reg, bool is_capture, Trace* trace)
+        : DeferredAction(ActionNode::STORE_POSITION, reg),
+          cp_offset_(trace->cp_offset()),
+          is_capture_(is_capture) {}
+    int cp_offset() { return cp_offset_; }
+    bool is_capture() { return is_capture_; }
+
+   private:
+    int cp_offset_;
+    bool is_capture_;
+    void set_cp_offset(int cp_offset) { cp_offset_ = cp_offset; }
+  };
+
+  class DeferredSetRegisterForLoop : public DeferredAction {
+   public:
+    DeferredSetRegisterForLoop(int reg, int value)
+        : DeferredAction(ActionNode::SET_REGISTER_FOR_LOOP, reg),
+          value_(value) {}
+    int value() { return value_; }
+
+   private:
+    int value_;
+  };
+
+  class DeferredClearCaptures : public DeferredAction {
+   public:
+    explicit DeferredClearCaptures(Interval range)
+        : DeferredAction(ActionNode::CLEAR_CAPTURES, -1), range_(range) {}
+    Interval range() { return range_; }
+
+   private:
+    Interval range_;
+  };
+
+  class DeferredIncrementRegister : public DeferredAction {
+   public:
+    explicit DeferredIncrementRegister(int reg)
+        : DeferredAction(ActionNode::INCREMENT_REGISTER, reg) {}
+  };
+
+  Trace()
+      : cp_offset_(0),
+        actions_(nullptr),
+        backtrack_(nullptr),
+        stop_node_(nullptr),
+        loop_label_(nullptr),
+        characters_preloaded_(0),
+        bound_checked_up_to_(0),
+        flush_budget_(100),
+        at_start_(UNKNOWN) {}
+
+  // End the trace.  This involves flushing the deferred actions in the trace
+  // and pushing a backtrack location onto the backtrack stack.  Once this is
+  // done we can start a new trace or go to one that has already been
+  // generated.
+  void Flush(RegExpCompiler* compiler, RegExpNode* successor);
+  int cp_offset() { return cp_offset_; }
+  DeferredAction* actions() { return actions_; }
+  // A trivial trace is one that has no deferred actions or other state that
+  // affects the assumptions used when generating code.  There is no recorded
+  // backtrack location in a trivial trace, so with a trivial trace we will
+  // generate code that, on a failure to match, gets the backtrack location
+  // from the backtrack stack rather than using a direct jump instruction.  We
+  // always start code generation with a trivial trace and non-trivial traces
+  // are created as we emit code for nodes or add to the list of deferred
+  // actions in the trace.  The location of the code generated for a node using
+  // a trivial trace is recorded in a label in the node so that gotos can be
+  // generated to that code.
+  bool is_trivial() {
+    return backtrack_ == nullptr && actions_ == nullptr && cp_offset_ == 0 &&
+           characters_preloaded_ == 0 && bound_checked_up_to_ == 0 &&
+           quick_check_performed_.characters() == 0 && at_start_ == UNKNOWN;
+  }
+  TriBool at_start() { return at_start_; }
+  void set_at_start(TriBool at_start) { at_start_ = at_start; }
+  Label* backtrack() { return backtrack_; }
+  Label* loop_label() { return loop_label_; }
+  RegExpNode* stop_node() { return stop_node_; }
+  int characters_preloaded() { return characters_preloaded_; }
+  int bound_checked_up_to() { return bound_checked_up_to_; }
+  int flush_budget() { return flush_budget_; }
+  QuickCheckDetails* quick_check_performed() { return &quick_check_performed_; }
+  bool mentions_reg(int reg);
+  // Returns true if a deferred position store exists to the specified
+  // register and stores the offset in the out-parameter.  Otherwise
+  // returns false.
+  bool GetStoredPosition(int reg, int* cp_offset);
+  // These set methods and AdvanceCurrentPositionInTrace should be used only on
+  // new traces - the intention is that traces are immutable after creation.
+  void add_action(DeferredAction* new_action) {
+    DCHECK(new_action->next_ == nullptr);
+    new_action->next_ = actions_;
+    actions_ = new_action;
+  }
+  void set_backtrack(Label* backtrack) { backtrack_ = backtrack; }
+  void set_stop_node(RegExpNode* node) { stop_node_ = node; }
+  void set_loop_label(Label* label) { loop_label_ = label; }
+  void set_characters_preloaded(int count) { characters_preloaded_ = count; }
+  void set_bound_checked_up_to(int to) { bound_checked_up_to_ = to; }
+  void set_flush_budget(int to) { flush_budget_ = to; }
+  void set_quick_check_performed(QuickCheckDetails* d) {
+    quick_check_performed_ = *d;
+  }
+  void InvalidateCurrentCharacter();
+  void AdvanceCurrentPositionInTrace(int by, RegExpCompiler* compiler);
+
+ private:
+  int FindAffectedRegisters(DynamicBitSet* affected_registers, Zone* zone);
+  void PerformDeferredActions(RegExpMacroAssembler* macro, int max_register,
+                              const DynamicBitSet& affected_registers,
+                              DynamicBitSet* registers_to_pop,
+                              DynamicBitSet* registers_to_clear, Zone* zone);
+  void RestoreAffectedRegisters(RegExpMacroAssembler* macro, int max_register,
+                                const DynamicBitSet& registers_to_pop,
+                                const DynamicBitSet& registers_to_clear);
+  int cp_offset_;
+  DeferredAction* actions_;
+  Label* backtrack_;
+  RegExpNode* stop_node_;
+  Label* loop_label_;
+  int characters_preloaded_;
+  int bound_checked_up_to_;
+  QuickCheckDetails quick_check_performed_;
+  int flush_budget_;
+  TriBool at_start_;
+};
+
+class GreedyLoopState {
+ public:
+  explicit GreedyLoopState(bool not_at_start);
+
+  Label* label() { return &label_; }
+  Trace* counter_backtrack_trace() { return &counter_backtrack_trace_; }
+
+ private:
+  Label label_;
+  Trace counter_backtrack_trace_;
+};
+
+struct PreloadState {
+  static const int kEatsAtLeastNotYetInitialized = -1;
+  bool preload_is_current_;
+  bool preload_has_checked_bounds_;
+  int preload_characters_;
+  int eats_at_least_;
+  void init() { eats_at_least_ = kEatsAtLeastNotYetInitialized; }
+};
+
+// Analysis performs assertion propagation and computes eats_at_least_ values.
+// See the comments on AssertionPropagator and EatsAtLeastPropagator for more
+// details.
+//
+// This method returns nullptr on success or a null-terminated failure message
+// on failure.
+const char* AnalyzeRegExp(Isolate* isolate, bool is_one_byte, RegExpNode* node);
+
+class FrequencyCollator {
+ public:
+  FrequencyCollator() : total_samples_(0) {
+    for (int i = 0; i < RegExpMacroAssembler::kTableSize; i++) {
+      frequencies_[i] = CharacterFrequency(i);
+    }
+  }
+
+  void CountCharacter(int character) {
+    int index = (character & RegExpMacroAssembler::kTableMask);
+    frequencies_[index].Increment();
+    total_samples_++;
+  }
+
+  // Does not measure in percent, but rather per-128 (the table size from the
+  // regexp macro assembler).
+  int Frequency(int in_character) {
+    DCHECK((in_character & RegExpMacroAssembler::kTableMask) == in_character);
+    if (total_samples_ < 1) return 1;  // Division by zero.
+    int freq_in_per128 =
+        (frequencies_[in_character].counter() * 128) / total_samples_;
+    return freq_in_per128;
+  }
+
+ private:
+  class CharacterFrequency {
+   public:
+    CharacterFrequency() : counter_(0), character_(-1) {}
+    explicit CharacterFrequency(int character)
+        : counter_(0), character_(character) {}
+
+    void Increment() { counter_++; }
+    int counter() { return counter_; }
+    int character() { return character_; }
+
+   private:
+    int counter_;
+    int character_;
+  };
+
+ private:
+  CharacterFrequency frequencies_[RegExpMacroAssembler::kTableSize];
+  int total_samples_;
+};
+
+class RegExpCompiler {
+ public:
+  RegExpCompiler(Isolate* isolate, Zone* zone, int capture_count,
+                 bool is_one_byte);
+
+  int AllocateRegister() {
+    if (next_register_ >= RegExpMacroAssembler::kMaxRegister) {
+      reg_exp_too_big_ = true;
+      return next_register_;
+    }
+    return next_register_++;
+  }
+
+  // Lookarounds to match lone surrogates for unicode character class matches
+  // are never nested. We can therefore reuse registers.
+  int UnicodeLookaroundStackRegister() {
+    if (unicode_lookaround_stack_register_ == kNoRegister) {
+      unicode_lookaround_stack_register_ = AllocateRegister();
+    }
+    return unicode_lookaround_stack_register_;
+  }
+
+  int UnicodeLookaroundPositionRegister() {
+    if (unicode_lookaround_position_register_ == kNoRegister) {
+      unicode_lookaround_position_register_ = AllocateRegister();
+    }
+    return unicode_lookaround_position_register_;
+  }
+
+  struct CompilationResult final {
+    explicit CompilationResult(const char* error_message)
+        : error_message(error_message) {}
+    CompilationResult(Object code, int registers)
+        : code(code), num_registers(registers) {}
+
+    static CompilationResult RegExpTooBig() {
+      return CompilationResult("RegExp too big");
+    }
+
+    bool Succeeded() const { return error_message == nullptr; }
+
+    const char* const error_message = nullptr;
+    Object code;
+    int num_registers = 0;
+  };
+
+  CompilationResult Assemble(Isolate* isolate, RegExpMacroAssembler* assembler,
+                             RegExpNode* start, int capture_count,
+                             Handle<String> pattern);
+
+  // If the regexp matching starts within a surrogate pair, step back to the
+  // lead surrogate and start matching from there.
+  static RegExpNode* OptionallyStepBackToLeadSurrogate(RegExpCompiler* compiler,
+                                                       RegExpNode* on_success,
+                                                       JSRegExp::Flags flags);
+
+  inline void AddWork(RegExpNode* node) {
+    if (!node->on_work_list() && !node->label()->is_bound()) {
+      node->set_on_work_list(true);
+      work_list_->push_back(node);
+    }
+  }
+
+  static const int kImplementationOffset = 0;
+  static const int kNumberOfRegistersOffset = 0;
+  static const int kCodeOffset = 1;
+
+  RegExpMacroAssembler* macro_assembler() { return macro_assembler_; }
+  EndNode* accept() { return accept_; }
+
+  static const int kMaxRecursion = 100;
+  inline int recursion_depth() { return recursion_depth_; }
+  inline void IncrementRecursionDepth() { recursion_depth_++; }
+  inline void DecrementRecursionDepth() { recursion_depth_--; }
+
+  void SetRegExpTooBig() { reg_exp_too_big_ = true; }
+
+  inline bool one_byte() { return one_byte_; }
+  inline bool optimize() { return optimize_; }
+  inline void set_optimize(bool value) { optimize_ = value; }
+  inline bool limiting_recursion() { return limiting_recursion_; }
+  inline void set_limiting_recursion(bool value) {
+    limiting_recursion_ = value;
+  }
+  bool read_backward() { return read_backward_; }
+  void set_read_backward(bool value) { read_backward_ = value; }
+  FrequencyCollator* frequency_collator() { return &frequency_collator_; }
+
+  int current_expansion_factor() { return current_expansion_factor_; }
+  void set_current_expansion_factor(int value) {
+    current_expansion_factor_ = value;
+  }
+
+  Isolate* isolate() const { return isolate_; }
+  Zone* zone() const { return zone_; }
+
+  static const int kNoRegister = -1;
+
+ private:
+  EndNode* accept_;
+  int next_register_;
+  int unicode_lookaround_stack_register_;
+  int unicode_lookaround_position_register_;
+  std::vector<RegExpNode*>* work_list_;
+  int recursion_depth_;
+  RegExpMacroAssembler* macro_assembler_;
+  bool one_byte_;
+  bool reg_exp_too_big_;
+  bool limiting_recursion_;
+  bool optimize_;
+  bool read_backward_;
+  int current_expansion_factor_;
+  FrequencyCollator frequency_collator_;
+  Isolate* isolate_;
+  Zone* zone_;
+};
+
+// Categorizes character ranges into BMP, non-BMP, lead, and trail surrogates.
+class UnicodeRangeSplitter {
+ public:
+  V8_EXPORT_PRIVATE UnicodeRangeSplitter(ZoneList<CharacterRange>* base);
+
+  static constexpr int kInitialSize = 8;
+  using CharacterRangeVector = base::SmallVector<CharacterRange, kInitialSize>;
+
+  const CharacterRangeVector* bmp() const { return &bmp_; }
+  const CharacterRangeVector* lead_surrogates() const {
+    return &lead_surrogates_;
+  }
+  const CharacterRangeVector* trail_surrogates() const {
+    return &trail_surrogates_;
+  }
+  const CharacterRangeVector* non_bmp() const { return &non_bmp_; }
+
+ private:
+  void AddRange(CharacterRange range);
+
+  CharacterRangeVector bmp_;
+  CharacterRangeVector lead_surrogates_;
+  CharacterRangeVector trail_surrogates_;
+  CharacterRangeVector non_bmp_;
+};
+
+// We need to check for the following characters: 0x39C 0x3BC 0x178.
+// TODO(jgruber): Move to CharacterRange.
+bool RangeContainsLatin1Equivalents(CharacterRange range);
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_COMPILER_H_
diff --git a/js/src/regexp/regexp-dotprinter.cc b/js/src/regexp/regexp-dotprinter.cc
new file mode 100644
index 0000000000..9bf800dfc2
--- /dev/null
+++ b/js/src/regexp/regexp-dotprinter.cc
@@ -0,0 +1,252 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-dotprinter.h"
+
+#include "regexp/regexp-compiler.h"
+
+namespace v8 {
+namespace internal {
+
+// -------------------------------------------------------------------
+// Dot/dotty output
+
+#ifdef DEBUG
+
+class DotPrinterImpl : public NodeVisitor {
+ public:
+  explicit DotPrinterImpl(std::ostream& os) : os_(os) {}
+  void PrintNode(const char* label, RegExpNode* node);
+  void Visit(RegExpNode* node);
+  void PrintAttributes(RegExpNode* from);
+  void PrintOnFailure(RegExpNode* from, RegExpNode* to);
+#define DECLARE_VISIT(Type) virtual void Visit##Type(Type##Node* that);
+  FOR_EACH_NODE_TYPE(DECLARE_VISIT)
+#undef DECLARE_VISIT
+ private:
+  std::ostream& os_;
+};
+
+void DotPrinterImpl::PrintNode(const char* label, RegExpNode* node) {
+  os_ << "digraph G {\n  graph [label=\"";
+  for (int i = 0; label[i]; i++) {
+    switch (label[i]) {
+      case '\\':
+        os_ << "\\\\";
+        break;
+      case '"':
+        os_ << "\"";
+        break;
+      default:
+        os_ << label[i];
+        break;
+    }
+  }
+  os_ << "\"];\n";
+  Visit(node);
+  os_ << "}" << std::endl;
+}
+
+void DotPrinterImpl::Visit(RegExpNode* node) {
+  if (node->info()->visited) return;
+  node->info()->visited = true;
+  node->Accept(this);
+}
+
+void DotPrinterImpl::PrintOnFailure(RegExpNode* from, RegExpNode* on_failure) {
+  os_ << "  n" << from << " -> n" << on_failure << " [style=dotted];\n";
+  Visit(on_failure);
+}
+
+class AttributePrinter {
+ public:
+  explicit AttributePrinter(std::ostream& os)  // NOLINT
+      : os_(os), first_(true) {}
+  void PrintSeparator() {
+    if (first_) {
+      first_ = false;
+    } else {
+      os_ << "|";
+    }
+  }
+  void PrintBit(const char* name, bool value) {
+    if (!value) return;
+    PrintSeparator();
+    os_ << "{" << name << "}";
+  }
+  void PrintPositive(const char* name, int value) {
+    if (value < 0) return;
+    PrintSeparator();
+    os_ << "{" << name << "|" << value << "}";
+  }
+
+ private:
+  std::ostream& os_;
+  bool first_;
+};
+
+void DotPrinterImpl::PrintAttributes(RegExpNode* that) {
+  os_ << "  a" << that << " [shape=Mrecord, color=grey, fontcolor=grey, "
+      << "margin=0.1, fontsize=10, label=\"{";
+  AttributePrinter printer(os_);
+  NodeInfo* info = that->info();
+  printer.PrintBit("NI", info->follows_newline_interest);
+  printer.PrintBit("WI", info->follows_word_interest);
+  printer.PrintBit("SI", info->follows_start_interest);
+  Label* label = that->label();
+  if (label->is_bound()) printer.PrintPositive("@", label->pos());
+  os_ << "}\"];\n"
+      << "  a" << that << " -> n" << that
+      << " [style=dashed, color=grey, arrowhead=none];\n";
+}
+
+void DotPrinterImpl::VisitChoice(ChoiceNode* that) {
+  os_ << "  n" << that << " [shape=Mrecord, label=\"?\"];\n";
+  for (int i = 0; i < that->alternatives()->length(); i++) {
+    GuardedAlternative alt = that->alternatives()->at(i);
+    os_ << "  n" << that << " -> n" << alt.node();
+  }
+  for (int i = 0; i < that->alternatives()->length(); i++) {
+    GuardedAlternative alt = that->alternatives()->at(i);
+    alt.node()->Accept(this);
+  }
+}
+
+void DotPrinterImpl::VisitLoopChoice(LoopChoiceNode* that) {
+  VisitChoice(that);
+}
+
+void DotPrinterImpl::VisitNegativeLookaroundChoice(
+    NegativeLookaroundChoiceNode* that) {
+  VisitChoice(that);
+}
+
+void DotPrinterImpl::VisitText(TextNode* that) {
+  Zone* zone = that->zone();
+  os_ << "  n" << that << " [label=\"";
+  for (int i = 0; i < that->elements()->length(); i++) {
+    if (i > 0) os_ << " ";
+    TextElement elm = that->elements()->at(i);
+    switch (elm.text_type()) {
+      case TextElement::ATOM: {
+        Vector<const uc16> data = elm.atom()->data();
+        for (int i = 0; i < data.length(); i++) {
+          os_ << static_cast<char>(data[i]);
+        }
+        break;
+      }
+      case TextElement::CHAR_CLASS: {
+        RegExpCharacterClass* node = elm.char_class();
+        os_ << "[";
+        if (node->is_negated()) os_ << "^";
+        for (int j = 0; j < node->ranges(zone)->length(); j++) {
+          CharacterRange range = node->ranges(zone)->at(j);
+          os_ << AsUC16(range.from()) << "-" << AsUC16(range.to());
+        }
+        os_ << "]";
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+  os_ << "\", shape=box, peripheries=2];\n";
+  PrintAttributes(that);
+  os_ << "  n" << that << " -> n" << that->on_success() << ";\n";
+  Visit(that->on_success());
+}
+
+void DotPrinterImpl::VisitBackReference(BackReferenceNode* that) {
+  os_ << "  n" << that << " [label=\"$" << that->start_register() << "..$"
+      << that->end_register() << "\", shape=doubleoctagon];\n";
+  PrintAttributes(that);
+  os_ << "  n" << that << " -> n" << that->on_success() << ";\n";
+  Visit(that->on_success());
+}
+
+void DotPrinterImpl::VisitEnd(EndNode* that) {
+  os_ << "  n" << that << " [style=bold, shape=point];\n";
+  PrintAttributes(that);
+}
+
+void DotPrinterImpl::VisitAssertion(AssertionNode* that) {
+  os_ << "  n" << that << " [";
+  switch (that->assertion_type()) {
+    case AssertionNode::AT_END:
+      os_ << "label=\"$\", shape=septagon";
+      break;
+    case AssertionNode::AT_START:
+      os_ << "label=\"^\", shape=septagon";
+      break;
+    case AssertionNode::AT_BOUNDARY:
+      os_ << "label=\"\\b\", shape=septagon";
+      break;
+    case AssertionNode::AT_NON_BOUNDARY:
+      os_ << "label=\"\\B\", shape=septagon";
+      break;
+    case AssertionNode::AFTER_NEWLINE:
+      os_ << "label=\"(?<=\\n)\", shape=septagon";
+      break;
+  }
+  os_ << "];\n";
+  PrintAttributes(that);
+  RegExpNode* successor = that->on_success();
+  os_ << "  n" << that << " -> n" << successor << ";\n";
+  Visit(successor);
+}
+
+void DotPrinterImpl::VisitAction(ActionNode* that) {
+  os_ << "  n" << that << " [";
+  switch (that->action_type_) {
+    case ActionNode::SET_REGISTER_FOR_LOOP:
+      os_ << "label=\"$" << that->data_.u_store_register.reg
+          << ":=" << that->data_.u_store_register.value << "\", shape=octagon";
+      break;
+    case ActionNode::INCREMENT_REGISTER:
+      os_ << "label=\"$" << that->data_.u_increment_register.reg
+          << "++\", shape=octagon";
+      break;
+    case ActionNode::STORE_POSITION:
+      os_ << "label=\"$" << that->data_.u_position_register.reg
+          << ":=$pos\", shape=octagon";
+      break;
+    case ActionNode::BEGIN_SUBMATCH:
+      os_ << "label=\"$" << that->data_.u_submatch.current_position_register
+          << ":=$pos,begin\", shape=septagon";
+      break;
+    case ActionNode::POSITIVE_SUBMATCH_SUCCESS:
+      os_ << "label=\"escape\", shape=septagon";
+      break;
+    case ActionNode::EMPTY_MATCH_CHECK:
+      os_ << "label=\"$" << that->data_.u_empty_match_check.start_register
+          << "=$pos?,$" << that->data_.u_empty_match_check.repetition_register
+          << "<" << that->data_.u_empty_match_check.repetition_limit
+          << "?\", shape=septagon";
+      break;
+    case ActionNode::CLEAR_CAPTURES: {
+      os_ << "label=\"clear $" << that->data_.u_clear_captures.range_from
+          << " to $" << that->data_.u_clear_captures.range_to
+          << "\", shape=septagon";
+      break;
+    }
+  }
+  os_ << "];\n";
+  PrintAttributes(that);
+  RegExpNode* successor = that->on_success();
+  os_ << "  n" << that << " -> n" << successor << ";\n";
+  Visit(successor);
+}
+
+#endif  // DEBUG
+
+void DotPrinter::DotPrint(const char* label, RegExpNode* node) {
+#ifdef DEBUG
+  StdoutStream os;
+  DotPrinterImpl printer(os);
+  printer.PrintNode(label, node);
+#endif  // DEBUG
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-dotprinter.h b/js/src/regexp/regexp-dotprinter.h
new file mode 100644
index 0000000000..b3b268f53a
--- /dev/null
+++ b/js/src/regexp/regexp-dotprinter.h
@@ -0,0 +1,22 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_DOTPRINTER_H_
+#define V8_REGEXP_REGEXP_DOTPRINTER_H_
+
+
+namespace v8 {
+namespace internal {
+
+class RegExpNode;
+
+class DotPrinter final : public AllStatic {
+ public:
+  static void DotPrint(const char* label, RegExpNode* node);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_DOTPRINTER_H_
diff --git a/js/src/regexp/regexp-interpreter.cc b/js/src/regexp/regexp-interpreter.cc
new file mode 100644
index 0000000000..6632cd7296
--- /dev/null
+++ b/js/src/regexp/regexp-interpreter.cc
@@ -0,0 +1,1053 @@
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// A simple interpreter for the Irregexp byte code.
+
+#include "regexp/regexp-interpreter.h"
+
+#include "regexp/regexp-bytecodes.h"
+#include "regexp/regexp-macro-assembler.h"
+#include "regexp/regexp-stack.h"  // For kMaximumStackSize.
+#include "regexp/regexp.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/uchar.h"
+#endif  // V8_INTL_SUPPORT
+
+// Use token threaded dispatch iff the compiler supports computed gotos and the
+// build argument v8_enable_regexp_interpreter_threaded_dispatch was set.
+#if V8_HAS_COMPUTED_GOTO && \
+    defined(V8_ENABLE_REGEXP_INTERPRETER_THREADED_DISPATCH)
+#define V8_USE_COMPUTED_GOTO 1
+#endif  // V8_HAS_COMPUTED_GOTO
+
+namespace v8 {
+namespace internal {
+
+namespace {
+
+bool BackRefMatchesNoCase(Isolate* isolate, int from, int current, int len,
+                          Vector<const uc16> subject, bool unicode) {
+  Address offset_a =
+      reinterpret_cast<Address>(const_cast<uc16*>(&subject.at(from)));
+  Address offset_b =
+      reinterpret_cast<Address>(const_cast<uc16*>(&subject.at(current)));
+  size_t length = len * kUC16Size;
+  return RegExpMacroAssembler::CaseInsensitiveCompareUC16(
+             offset_a, offset_b, length, unicode ? nullptr : isolate) == 1;
+}
+
+bool BackRefMatchesNoCase(Isolate* isolate, int from, int current, int len,
+                          Vector<const uint8_t> subject, bool unicode) {
+  // For Latin1 characters the unicode flag makes no difference.
+  for (int i = 0; i < len; i++) {
+    unsigned int old_char = subject[from++];
+    unsigned int new_char = subject[current++];
+    if (old_char == new_char) continue;
+    // Convert both characters to lower case.
+    old_char |= 0x20;
+    new_char |= 0x20;
+    if (old_char != new_char) return false;
+    // Not letters in the ASCII range and Latin-1 range.
+    if (!(old_char - 'a' <= 'z' - 'a') &&
+        !(old_char - 224 <= 254 - 224 && old_char != 247)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+#ifdef DEBUG
+void MaybeTraceInterpreter(const byte* code_base, const byte* pc,
+                           int stack_depth, int current_position,
+                           uint32_t current_char, int bytecode_length,
+                           const char* bytecode_name) {
+  if (FLAG_trace_regexp_bytecodes) {
+    const bool printable = std::isprint(current_char);
+    const char* format =
+        printable
+            ? "pc = %02x, sp = %d, curpos = %d, curchar = %08x (%c), bc = "
+            : "pc = %02x, sp = %d, curpos = %d, curchar = %08x .%c., bc = ";
+    PrintF(format, pc - code_base, stack_depth, current_position, current_char,
+           printable ? current_char : '.');
+
+    RegExpBytecodeDisassembleSingle(code_base, pc);
+  }
+}
+#endif  // DEBUG
+
+int32_t Load32Aligned(const byte* pc) {
+  DCHECK_EQ(0, reinterpret_cast<intptr_t>(pc) & 3);
+  return *reinterpret_cast<const int32_t*>(pc);
+}
+
+int32_t Load16Aligned(const byte* pc) {
+  DCHECK_EQ(0, reinterpret_cast<intptr_t>(pc) & 1);
+  return *reinterpret_cast<const uint16_t*>(pc);
+}
+
+// A simple abstraction over the backtracking stack used by the interpreter.
+//
+// Despite the name 'backtracking' stack, it's actually used as a generic stack
+// that stores both program counters (= offsets into the bytecode) and generic
+// integer values.
+class BacktrackStack {
+ public:
+  BacktrackStack() = default;
+
+  V8_WARN_UNUSED_RESULT bool push(int v) {
+    data_.emplace_back(v);
+    return (static_cast<int>(data_.size()) <= kMaxSize);
+  }
+  int peek() const {
+    DCHECK(!data_.empty());
+    return data_.back();
+  }
+  int pop() {
+    int v = peek();
+    data_.pop_back();
+    return v;
+  }
+
+  // The 'sp' is the index of the first empty element in the stack.
+  int sp() const { return static_cast<int>(data_.size()); }
+  void set_sp(int new_sp) {
+    DCHECK_LE(new_sp, sp());
+    data_.resize_no_init(new_sp);
+  }
+
+ private:
+  // Semi-arbitrary. Should be large enough for common cases to remain in the
+  // static stack-allocated backing store, but small enough not to waste space.
+  static constexpr int kStaticCapacity = 64;
+
+  using ValueT = int;
+  base::SmallVector<ValueT, kStaticCapacity> data_;
+
+  static constexpr int kMaxSize =
+      RegExpStack::kMaximumStackSize / sizeof(ValueT);
+
+  DISALLOW_COPY_AND_ASSIGN(BacktrackStack);
+};
+
+IrregexpInterpreter::Result ThrowStackOverflow(Isolate* isolate,
+                                               RegExp::CallOrigin call_origin) {
+  CHECK(call_origin == RegExp::CallOrigin::kFromRuntime);
+  // We abort interpreter execution after the stack overflow is thrown, and thus
+  // allow allocation here despite the outer DisallowHeapAllocationScope.
+  AllowHeapAllocation yes_gc;
+  isolate->StackOverflow();
+  return IrregexpInterpreter::EXCEPTION;
+}
+
+// Only throws if called from the runtime, otherwise just returns the EXCEPTION
+// status code.
+IrregexpInterpreter::Result MaybeThrowStackOverflow(
+    Isolate* isolate, RegExp::CallOrigin call_origin) {
+  if (call_origin == RegExp::CallOrigin::kFromRuntime) {
+    return ThrowStackOverflow(isolate, call_origin);
+  } else {
+    return IrregexpInterpreter::EXCEPTION;
+  }
+}
+
+template <typename Char>
+void UpdateCodeAndSubjectReferences(
+    Isolate* isolate, Handle<ByteArray> code_array,
+    Handle<String> subject_string, ByteArray* code_array_out,
+    const byte** code_base_out, const byte** pc_out, String* subject_string_out,
+    Vector<const Char>* subject_string_vector_out) {
+  DisallowHeapAllocation no_gc;
+
+  if (*code_base_out != code_array->GetDataStartAddress()) {
+    *code_array_out = *code_array;
+    const intptr_t pc_offset = *pc_out - *code_base_out;
+    DCHECK_GT(pc_offset, 0);
+    *code_base_out = code_array->GetDataStartAddress();
+    *pc_out = *code_base_out + pc_offset;
+  }
+
+  DCHECK(subject_string->IsFlat());
+  *subject_string_out = *subject_string;
+  *subject_string_vector_out = subject_string->GetCharVector<Char>(no_gc);
+}
+
+// Runs all pending interrupts and updates unhandlified object references if
+// necessary.
+template <typename Char>
+IrregexpInterpreter::Result HandleInterrupts(
+    Isolate* isolate, RegExp::CallOrigin call_origin, ByteArray* code_array_out,
+    String* subject_string_out, const byte** code_base_out,
+    Vector<const Char>* subject_string_vector_out, const byte** pc_out) {
+  DisallowHeapAllocation no_gc;
+
+  StackLimitCheck check(isolate);
+  bool js_has_overflowed = check.JsHasOverflowed();
+
+  if (call_origin == RegExp::CallOrigin::kFromJs) {
+    // Direct calls from JavaScript can be interrupted in two ways:
+    // 1. A real stack overflow, in which case we let the caller throw the
+    //    exception.
+    // 2. The stack guard was used to interrupt execution for another purpose,
+    //    forcing the call through the runtime system.
+    if (js_has_overflowed) {
+      return IrregexpInterpreter::EXCEPTION;
+    } else if (check.InterruptRequested()) {
+      return IrregexpInterpreter::RETRY;
+    }
+  } else {
+    DCHECK(call_origin == RegExp::CallOrigin::kFromRuntime);
+    // Prepare for possible GC.
+    HandleScope handles(isolate);
+    Handle<ByteArray> code_handle(*code_array_out, isolate);
+    Handle<String> subject_handle(*subject_string_out, isolate);
+
+    if (js_has_overflowed) {
+      return ThrowStackOverflow(isolate, call_origin);
+    } else if (check.InterruptRequested()) {
+      const bool was_one_byte =
+          String::IsOneByteRepresentationUnderneath(*subject_string_out);
+      Object result;
+      {
+        AllowHeapAllocation yes_gc;
+        result = isolate->stack_guard()->HandleInterrupts();
+      }
+      if (result.IsException(isolate)) {
+        return IrregexpInterpreter::EXCEPTION;
+      }
+
+      // If we changed between a LATIN1 and a UC16 string, we need to restart
+      // regexp matching with the appropriate template instantiation of
+      // RawMatch.
+      if (String::IsOneByteRepresentationUnderneath(*subject_handle) !=
+          was_one_byte) {
+        return IrregexpInterpreter::RETRY;
+      }
+
+      UpdateCodeAndSubjectReferences(
+          isolate, code_handle, subject_handle, code_array_out, code_base_out,
+          pc_out, subject_string_out, subject_string_vector_out);
+    }
+  }
+
+  return IrregexpInterpreter::SUCCESS;
+}
+
+bool CheckBitInTable(const uint32_t current_char, const byte* const table) {
+  int mask = RegExpMacroAssembler::kTableMask;
+  int b = table[(current_char & mask) >> kBitsPerByteLog2];
+  int bit = (current_char & (kBitsPerByte - 1));
+  return (b & (1 << bit)) != 0;
+}
+
+// If computed gotos are supported by the compiler, we can get addresses to
+// labels directly in C/C++. Every bytecode handler has its own label and we
+// store the addresses in a dispatch table indexed by bytecode. To execute the
+// next handler we simply jump (goto) directly to its address.
+#if V8_USE_COMPUTED_GOTO
+#define BC_LABEL(name) BC_##name:
+#define DECODE()                                                   \
+  do {                                                             \
+    next_insn = Load32Aligned(next_pc);                            \
+    next_handler_addr = dispatch_table[next_insn & BYTECODE_MASK]; \
+  } while (false)
+#define DISPATCH()  \
+  pc = next_pc;     \
+  insn = next_insn; \
+  goto* next_handler_addr
+// Without computed goto support, we fall back to a simple switch-based
+// dispatch (A large switch statement inside a loop with a case for every
+// bytecode).
+#else  // V8_USE_COMPUTED_GOTO
+#define BC_LABEL(name) case BC_##name:
+#define DECODE() next_insn = Load32Aligned(next_pc)
+#define DISPATCH()  \
+  pc = next_pc;     \
+  insn = next_insn; \
+  goto switch_dispatch_continuation
+#endif  // V8_USE_COMPUTED_GOTO
+
+// ADVANCE/SET_PC_FROM_OFFSET are separated from DISPATCH, because ideally some
+// instructions can be executed between ADVANCE/SET_PC_FROM_OFFSET and DISPATCH.
+// We want those two macros as far apart as possible, because the goto in
+// DISPATCH is dependent on a memory load in ADVANCE/SET_PC_FROM_OFFSET. If we
+// don't hit the cache and have to fetch the next handler address from physical
+// memory, instructions between ADVANCE/SET_PC_FROM_OFFSET and DISPATCH can
+// potentially be executed unconditionally, reducing memory stall.
+#define ADVANCE(name)                             \
+  next_pc = pc + RegExpBytecodeLength(BC_##name); \
+  DECODE()
+#define SET_PC_FROM_OFFSET(offset) \
+  next_pc = code_base + offset;    \
+  DECODE()
+
+#ifdef DEBUG
+#define BYTECODE(name)                                                \
+  BC_LABEL(name)                                                      \
+  MaybeTraceInterpreter(code_base, pc, backtrack_stack.sp(), current, \
+                        current_char, RegExpBytecodeLength(BC_##name), #name);
+#else
+#define BYTECODE(name) BC_LABEL(name)
+#endif  // DEBUG
+
+template <typename Char>
+IrregexpInterpreter::Result RawMatch(Isolate* isolate, ByteArray code_array,
+                                     String subject_string,
+                                     Vector<const Char> subject, int* registers,
+                                     int current, uint32_t current_char,
+                                     RegExp::CallOrigin call_origin,
+                                     const uint32_t backtrack_limit) {
+  DisallowHeapAllocation no_gc;
+
+#if V8_USE_COMPUTED_GOTO
+
+// We have to make sure that no OOB access to the dispatch table is possible and
+// all values are valid label addresses.
+// Otherwise jumps to arbitrary addresses could potentially happen.
+// This is ensured as follows:
+// Every index to the dispatch table gets masked using BYTECODE_MASK in
+// DECODE(). This way we can only get values between 0 (only the least
+// significant byte of an integer is used) and kRegExpPaddedBytecodeCount - 1
+// (BYTECODE_MASK is defined to be exactly this value).
+// All entries from kRegExpBytecodeCount to kRegExpPaddedBytecodeCount have to
+// be filled with BREAKs (invalid operation).
+
+// Fill dispatch table from last defined bytecode up to the next power of two
+// with BREAK (invalid operation).
+// TODO(pthier): Find a way to fill up automatically (at compile time)
+// 59 real bytecodes -> 5 fillers
+#define BYTECODE_FILLER_ITERATOR(V) \
+  V(BREAK) /* 1 */                  \
+  V(BREAK) /* 2 */                  \
+  V(BREAK) /* 3 */                  \
+  V(BREAK) /* 4 */                  \
+  V(BREAK) /* 5 */
+
+#define COUNT(...) +1
+  static constexpr int kRegExpBytecodeFillerCount =
+      BYTECODE_FILLER_ITERATOR(COUNT);
+#undef COUNT
+
+  // Make sure kRegExpPaddedBytecodeCount is actually the closest possible power
+  // of two.
+  DCHECK_EQ(kRegExpPaddedBytecodeCount,
+            base::bits::RoundUpToPowerOfTwo32(kRegExpBytecodeCount));
+
+  // Make sure every bytecode we get by using BYTECODE_MASK is well defined.
+  STATIC_ASSERT(kRegExpBytecodeCount <= kRegExpPaddedBytecodeCount);
+  STATIC_ASSERT(kRegExpBytecodeCount + kRegExpBytecodeFillerCount ==
+                kRegExpPaddedBytecodeCount);
+
+#define DECLARE_DISPATCH_TABLE_ENTRY(name, ...) &&BC_##name,
+  static const void* const dispatch_table[kRegExpPaddedBytecodeCount] = {
+      BYTECODE_ITERATOR(DECLARE_DISPATCH_TABLE_ENTRY)
+          BYTECODE_FILLER_ITERATOR(DECLARE_DISPATCH_TABLE_ENTRY)};
+#undef DECLARE_DISPATCH_TABLE_ENTRY
+#undef BYTECODE_FILLER_ITERATOR
+
+#endif  // V8_USE_COMPUTED_GOTO
+
+  const byte* pc = code_array.GetDataStartAddress();
+  const byte* code_base = pc;
+
+  BacktrackStack backtrack_stack;
+
+  uint32_t backtrack_count = 0;
+
+#ifdef DEBUG
+  if (FLAG_trace_regexp_bytecodes) {
+    PrintF("\n\nStart bytecode interpreter\n\n");
+  }
+#endif
+
+  while (true) {
+    const byte* next_pc = pc;
+    int32_t insn;
+    int32_t next_insn;
+#if V8_USE_COMPUTED_GOTO
+    const void* next_handler_addr;
+    DECODE();
+    DISPATCH();
+#else
+    insn = Load32Aligned(pc);
+    switch (insn & BYTECODE_MASK) {
+#endif  // V8_USE_COMPUTED_GOTO
+    BYTECODE(BREAK) { UNREACHABLE(); }
+    BYTECODE(PUSH_CP) {
+      ADVANCE(PUSH_CP);
+      if (!backtrack_stack.push(current)) {
+        return MaybeThrowStackOverflow(isolate, call_origin);
+      }
+      DISPATCH();
+    }
+    BYTECODE(PUSH_BT) {
+      ADVANCE(PUSH_BT);
+      if (!backtrack_stack.push(Load32Aligned(pc + 4))) {
+        return MaybeThrowStackOverflow(isolate, call_origin);
+      }
+      DISPATCH();
+    }
+    BYTECODE(PUSH_REGISTER) {
+      ADVANCE(PUSH_REGISTER);
+      if (!backtrack_stack.push(registers[insn >> BYTECODE_SHIFT])) {
+        return MaybeThrowStackOverflow(isolate, call_origin);
+      }
+      DISPATCH();
+    }
+    BYTECODE(SET_REGISTER) {
+      ADVANCE(SET_REGISTER);
+      registers[insn >> BYTECODE_SHIFT] = Load32Aligned(pc + 4);
+      DISPATCH();
+    }
+    BYTECODE(ADVANCE_REGISTER) {
+      ADVANCE(ADVANCE_REGISTER);
+      registers[insn >> BYTECODE_SHIFT] += Load32Aligned(pc + 4);
+      DISPATCH();
+    }
+    BYTECODE(SET_REGISTER_TO_CP) {
+      ADVANCE(SET_REGISTER_TO_CP);
+      registers[insn >> BYTECODE_SHIFT] = current + Load32Aligned(pc + 4);
+      DISPATCH();
+    }
+    BYTECODE(SET_CP_TO_REGISTER) {
+      ADVANCE(SET_CP_TO_REGISTER);
+      current = registers[insn >> BYTECODE_SHIFT];
+      DISPATCH();
+    }
+    BYTECODE(SET_REGISTER_TO_SP) {
+      ADVANCE(SET_REGISTER_TO_SP);
+      registers[insn >> BYTECODE_SHIFT] = backtrack_stack.sp();
+      DISPATCH();
+    }
+    BYTECODE(SET_SP_TO_REGISTER) {
+      ADVANCE(SET_SP_TO_REGISTER);
+      backtrack_stack.set_sp(registers[insn >> BYTECODE_SHIFT]);
+      DISPATCH();
+    }
+    BYTECODE(POP_CP) {
+      ADVANCE(POP_CP);
+      current = backtrack_stack.pop();
+      DISPATCH();
+    }
+    BYTECODE(POP_BT) {
+      STATIC_ASSERT(JSRegExp::kNoBacktrackLimit == 0);
+      if (++backtrack_count == backtrack_limit) {
+        // Exceeded limits are treated as a failed match.
+        return IrregexpInterpreter::FAILURE;
+      }
+
+      IrregexpInterpreter::Result return_code =
+          HandleInterrupts(isolate, call_origin, &code_array, &subject_string,
+                           &code_base, &subject, &pc);
+      if (return_code != IrregexpInterpreter::SUCCESS) return return_code;
+
+      SET_PC_FROM_OFFSET(backtrack_stack.pop());
+      DISPATCH();
+    }
+    BYTECODE(POP_REGISTER) {
+      ADVANCE(POP_REGISTER);
+      registers[insn >> BYTECODE_SHIFT] = backtrack_stack.pop();
+      DISPATCH();
+    }
+    BYTECODE(FAIL) {
+      isolate->counters()->regexp_backtracks()->AddSample(
+          static_cast<int>(backtrack_count));
+      return IrregexpInterpreter::FAILURE;
+    }
+    BYTECODE(SUCCEED) {
+      isolate->counters()->regexp_backtracks()->AddSample(
+          static_cast<int>(backtrack_count));
+      return IrregexpInterpreter::SUCCESS;
+    }
+    BYTECODE(ADVANCE_CP) {
+      ADVANCE(ADVANCE_CP);
+      current += insn >> BYTECODE_SHIFT;
+      DISPATCH();
+    }
+    BYTECODE(GOTO) {
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      DISPATCH();
+    }
+    BYTECODE(ADVANCE_CP_AND_GOTO) {
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      current += insn >> BYTECODE_SHIFT;
+      DISPATCH();
+    }
+    BYTECODE(CHECK_GREEDY) {
+      if (current == backtrack_stack.peek()) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+        backtrack_stack.pop();
+      } else {
+        ADVANCE(CHECK_GREEDY);
+      }
+      DISPATCH();
+    }
+    BYTECODE(LOAD_CURRENT_CHAR) {
+      int pos = current + (insn >> BYTECODE_SHIFT);
+      if (pos >= subject.length() || pos < 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(LOAD_CURRENT_CHAR);
+        current_char = subject[pos];
+      }
+      DISPATCH();
+    }
+    BYTECODE(LOAD_CURRENT_CHAR_UNCHECKED) {
+      ADVANCE(LOAD_CURRENT_CHAR_UNCHECKED);
+      int pos = current + (insn >> BYTECODE_SHIFT);
+      current_char = subject[pos];
+      DISPATCH();
+    }
+    BYTECODE(LOAD_2_CURRENT_CHARS) {
+      int pos = current + (insn >> BYTECODE_SHIFT);
+      if (pos + 2 > subject.length() || pos < 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(LOAD_2_CURRENT_CHARS);
+        Char next = subject[pos + 1];
+        current_char = (subject[pos] | (next << (kBitsPerByte * sizeof(Char))));
+      }
+      DISPATCH();
+    }
+    BYTECODE(LOAD_2_CURRENT_CHARS_UNCHECKED) {
+      ADVANCE(LOAD_2_CURRENT_CHARS_UNCHECKED);
+      int pos = current + (insn >> BYTECODE_SHIFT);
+      Char next = subject[pos + 1];
+      current_char = (subject[pos] | (next << (kBitsPerByte * sizeof(Char))));
+      DISPATCH();
+    }
+    BYTECODE(LOAD_4_CURRENT_CHARS) {
+      DCHECK_EQ(1, sizeof(Char));
+      int pos = current + (insn >> BYTECODE_SHIFT);
+      if (pos + 4 > subject.length() || pos < 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(LOAD_4_CURRENT_CHARS);
+        Char next1 = subject[pos + 1];
+        Char next2 = subject[pos + 2];
+        Char next3 = subject[pos + 3];
+        current_char =
+            (subject[pos] | (next1 << 8) | (next2 << 16) | (next3 << 24));
+      }
+      DISPATCH();
+    }
+    BYTECODE(LOAD_4_CURRENT_CHARS_UNCHECKED) {
+      ADVANCE(LOAD_4_CURRENT_CHARS_UNCHECKED);
+      DCHECK_EQ(1, sizeof(Char));
+      int pos = current + (insn >> BYTECODE_SHIFT);
+      Char next1 = subject[pos + 1];
+      Char next2 = subject[pos + 2];
+      Char next3 = subject[pos + 3];
+      current_char =
+          (subject[pos] | (next1 << 8) | (next2 << 16) | (next3 << 24));
+      DISPATCH();
+    }
+    BYTECODE(CHECK_4_CHARS) {
+      uint32_t c = Load32Aligned(pc + 4);
+      if (c == current_char) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_4_CHARS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_CHAR) {
+      uint32_t c = (insn >> BYTECODE_SHIFT);
+      if (c == current_char) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_4_CHARS) {
+      uint32_t c = Load32Aligned(pc + 4);
+      if (c != current_char) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_NOT_4_CHARS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_CHAR) {
+      uint32_t c = (insn >> BYTECODE_SHIFT);
+      if (c != current_char) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_NOT_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(AND_CHECK_4_CHARS) {
+      uint32_t c = Load32Aligned(pc + 4);
+      if (c == (current_char & Load32Aligned(pc + 8))) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+      } else {
+        ADVANCE(AND_CHECK_4_CHARS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(AND_CHECK_CHAR) {
+      uint32_t c = (insn >> BYTECODE_SHIFT);
+      if (c == (current_char & Load32Aligned(pc + 4))) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(AND_CHECK_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(AND_CHECK_NOT_4_CHARS) {
+      uint32_t c = Load32Aligned(pc + 4);
+      if (c != (current_char & Load32Aligned(pc + 8))) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+      } else {
+        ADVANCE(AND_CHECK_NOT_4_CHARS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(AND_CHECK_NOT_CHAR) {
+      uint32_t c = (insn >> BYTECODE_SHIFT);
+      if (c != (current_char & Load32Aligned(pc + 4))) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(AND_CHECK_NOT_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(MINUS_AND_CHECK_NOT_CHAR) {
+      uint32_t c = (insn >> BYTECODE_SHIFT);
+      uint32_t minus = Load16Aligned(pc + 4);
+      uint32_t mask = Load16Aligned(pc + 6);
+      if (c != ((current_char - minus) & mask)) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(MINUS_AND_CHECK_NOT_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_CHAR_IN_RANGE) {
+      uint32_t from = Load16Aligned(pc + 4);
+      uint32_t to = Load16Aligned(pc + 6);
+      if (from <= current_char && current_char <= to) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_CHAR_IN_RANGE);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_CHAR_NOT_IN_RANGE) {
+      uint32_t from = Load16Aligned(pc + 4);
+      uint32_t to = Load16Aligned(pc + 6);
+      if (from > current_char || current_char > to) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_CHAR_NOT_IN_RANGE);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_BIT_IN_TABLE) {
+      if (CheckBitInTable(current_char, pc + 8)) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_BIT_IN_TABLE);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_LT) {
+      uint32_t limit = (insn >> BYTECODE_SHIFT);
+      if (current_char < limit) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_LT);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_GT) {
+      uint32_t limit = (insn >> BYTECODE_SHIFT);
+      if (current_char > limit) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_GT);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_REGISTER_LT) {
+      if (registers[insn >> BYTECODE_SHIFT] < Load32Aligned(pc + 4)) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_REGISTER_LT);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_REGISTER_GE) {
+      if (registers[insn >> BYTECODE_SHIFT] >= Load32Aligned(pc + 4)) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_REGISTER_GE);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_REGISTER_EQ_POS) {
+      if (registers[insn >> BYTECODE_SHIFT] == current) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_REGISTER_EQ_POS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_REGS_EQUAL) {
+      if (registers[insn >> BYTECODE_SHIFT] ==
+          registers[Load32Aligned(pc + 4)]) {
+        ADVANCE(CHECK_NOT_REGS_EQUAL);
+      } else {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF) {
+      int from = registers[insn >> BYTECODE_SHIFT];
+      int len = registers[(insn >> BYTECODE_SHIFT) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current + len > subject.length() ||
+            CompareChars(&subject[from], &subject[current], len) != 0) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        current += len;
+      }
+      ADVANCE(CHECK_NOT_BACK_REF);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_BACKWARD) {
+      int from = registers[insn >> BYTECODE_SHIFT];
+      int len = registers[(insn >> BYTECODE_SHIFT) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current - len < 0 ||
+            CompareChars(&subject[from], &subject[current - len], len) != 0) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        current -= len;
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_BACKWARD);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_NO_CASE_UNICODE) {
+      int from = registers[insn >> BYTECODE_SHIFT];
+      int len = registers[(insn >> BYTECODE_SHIFT) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current + len > subject.length() ||
+            !BackRefMatchesNoCase(isolate, from, current, len, subject, true)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        current += len;
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_NO_CASE_UNICODE);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_NO_CASE) {
+      int from = registers[insn >> BYTECODE_SHIFT];
+      int len = registers[(insn >> BYTECODE_SHIFT) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current + len > subject.length() ||
+            !BackRefMatchesNoCase(isolate, from, current, len, subject,
+                                  false)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        current += len;
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_NO_CASE);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_NO_CASE_UNICODE_BACKWARD) {
+      int from = registers[insn >> BYTECODE_SHIFT];
+      int len = registers[(insn >> BYTECODE_SHIFT) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current - len < 0 ||
+            !BackRefMatchesNoCase(isolate, from, current - len, len, subject,
+                                  true)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        current -= len;
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_NO_CASE_UNICODE_BACKWARD);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_NO_CASE_BACKWARD) {
+      int from = registers[insn >> BYTECODE_SHIFT];
+      int len = registers[(insn >> BYTECODE_SHIFT) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current - len < 0 ||
+            !BackRefMatchesNoCase(isolate, from, current - len, len, subject,
+                                  false)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        current -= len;
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_NO_CASE_BACKWARD);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_AT_START) {
+      if (current + (insn >> BYTECODE_SHIFT) == 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_AT_START);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_AT_START) {
+      if (current + (insn >> BYTECODE_SHIFT) == 0) {
+        ADVANCE(CHECK_NOT_AT_START);
+      } else {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      }
+      DISPATCH();
+    }
+    BYTECODE(SET_CURRENT_POSITION_FROM_END) {
+      ADVANCE(SET_CURRENT_POSITION_FROM_END);
+      int by = static_cast<uint32_t>(insn) >> BYTECODE_SHIFT;
+      if (subject.length() - current > by) {
+        current = subject.length() - by;
+        current_char = subject[current - 1];
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_CURRENT_POSITION) {
+      int pos = current + (insn >> BYTECODE_SHIFT);
+      if (pos > subject.length() || pos < 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_CURRENT_POSITION);
+      }
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_CHAR) {
+      int load_offset = (insn >> BYTECODE_SHIFT);
+      uint32_t advance = Load16Aligned(pc + 4);
+      uint32_t c = Load16Aligned(pc + 6);
+      while (static_cast<uintptr_t>(current + load_offset) <
+             static_cast<uintptr_t>(subject.length())) {
+        current_char = subject[current + load_offset];
+        if (c == current_char) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+          DISPATCH();
+        }
+        current += advance;
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_CHAR_AND) {
+      int load_offset = (insn >> BYTECODE_SHIFT);
+      uint16_t advance = Load16Aligned(pc + 4);
+      uint16_t c = Load16Aligned(pc + 6);
+      uint32_t mask = Load32Aligned(pc + 8);
+      int32_t maximum_offset = Load32Aligned(pc + 12);
+      while (static_cast<uintptr_t>(current + maximum_offset) <=
+             static_cast<uintptr_t>(subject.length())) {
+        current_char = subject[current + load_offset];
+        if (c == (current_char & mask)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 16));
+          DISPATCH();
+        }
+        current += advance;
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 20));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_CHAR_POS_CHECKED) {
+      int load_offset = (insn >> BYTECODE_SHIFT);
+      uint16_t advance = Load16Aligned(pc + 4);
+      uint16_t c = Load16Aligned(pc + 6);
+      int32_t maximum_offset = Load32Aligned(pc + 8);
+      while (static_cast<uintptr_t>(current + maximum_offset) <=
+             static_cast<uintptr_t>(subject.length())) {
+        current_char = subject[current + load_offset];
+        if (c == current_char) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+          DISPATCH();
+        }
+        current += advance;
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 16));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_BIT_IN_TABLE) {
+      int load_offset = (insn >> BYTECODE_SHIFT);
+      uint32_t advance = Load16Aligned(pc + 4);
+      const byte* table = pc + 8;
+      while (static_cast<uintptr_t>(current + load_offset) <
+             static_cast<uintptr_t>(subject.length())) {
+        current_char = subject[current + load_offset];
+        if (CheckBitInTable(current_char, table)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 24));
+          DISPATCH();
+        }
+        current += advance;
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 28));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_GT_OR_NOT_BIT_IN_TABLE) {
+      int load_offset = (insn >> BYTECODE_SHIFT);
+      uint16_t advance = Load16Aligned(pc + 4);
+      uint16_t limit = Load16Aligned(pc + 6);
+      const byte* table = pc + 8;
+      while (static_cast<uintptr_t>(current + load_offset) <
+             static_cast<uintptr_t>(subject.length())) {
+        current_char = subject[current + load_offset];
+        if (current_char > limit) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 24));
+          DISPATCH();
+        }
+        if (!CheckBitInTable(current_char, table)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 24));
+          DISPATCH();
+        }
+        current += advance;
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 28));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_CHAR_OR_CHAR) {
+      int load_offset = (insn >> BYTECODE_SHIFT);
+      uint32_t advance = Load32Aligned(pc + 4);
+      uint16_t c = Load16Aligned(pc + 8);
+      uint16_t c2 = Load16Aligned(pc + 10);
+      while (static_cast<uintptr_t>(current + load_offset) <
+             static_cast<uintptr_t>(subject.length())) {
+        current_char = subject[current + load_offset];
+        // The two if-statements below are split up intentionally, as combining
+        // them seems to result in register allocation behaving quite
+        // differently and slowing down the resulting code.
+        if (c == current_char) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+          DISPATCH();
+        }
+        if (c2 == current_char) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+          DISPATCH();
+        }
+        current += advance;
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 16));
+      DISPATCH();
+    }
+#if V8_USE_COMPUTED_GOTO
+// Lint gets confused a lot if we just use !V8_USE_COMPUTED_GOTO or ifndef
+// V8_USE_COMPUTED_GOTO here.
+#else
+      default:
+        UNREACHABLE();
+    }
+  // Label we jump to in DISPATCH(). There must be no instructions between the
+  // end of the switch, this label and the end of the loop.
+  switch_dispatch_continuation : {}
+#endif  // V8_USE_COMPUTED_GOTO
+  }
+}
+
+#undef BYTECODE
+#undef DISPATCH
+#undef DECODE
+#undef SET_PC_FROM_OFFSET
+#undef ADVANCE
+#undef BC_LABEL
+#undef V8_USE_COMPUTED_GOTO
+
+}  // namespace
+
+// static
+IrregexpInterpreter::Result IrregexpInterpreter::Match(
+    Isolate* isolate, JSRegExp regexp, String subject_string, int* registers,
+    int registers_length, int start_position, RegExp::CallOrigin call_origin) {
+  if (FLAG_regexp_tier_up) {
+    regexp.TierUpTick();
+  }
+
+  bool is_one_byte = String::IsOneByteRepresentationUnderneath(subject_string);
+  ByteArray code_array = ByteArray::cast(regexp.Bytecode(is_one_byte));
+
+  return MatchInternal(isolate, code_array, subject_string, registers,
+                       registers_length, start_position, call_origin,
+                       regexp.BacktrackLimit());
+}
+
+IrregexpInterpreter::Result IrregexpInterpreter::MatchInternal(
+    Isolate* isolate, ByteArray code_array, String subject_string,
+    int* registers, int registers_length, int start_position,
+    RegExp::CallOrigin call_origin, uint32_t backtrack_limit) {
+  DCHECK(subject_string.IsFlat());
+
+  // Note: Heap allocation *is* allowed in two situations if calling from
+  // Runtime:
+  // 1. When creating & throwing a stack overflow exception. The interpreter
+  //    aborts afterwards, and thus possible-moved objects are never used.
+  // 2. When handling interrupts. We manually relocate unhandlified references
+  //    after interrupts have run.
+  DisallowHeapAllocation no_gc;
+
+  // Reset registers to -1 (=undefined).
+  // This is necessary because registers are only written when a
+  // capture group matched.
+  // Resetting them ensures that previous matches are cleared.
+  memset(registers, -1, sizeof(registers[0]) * registers_length);
+
+  uc16 previous_char = '\n';
+  String::FlatContent subject_content = subject_string.GetFlatContent(no_gc);
+  if (subject_content.IsOneByte()) {
+    Vector<const uint8_t> subject_vector = subject_content.ToOneByteVector();
+    if (start_position != 0) previous_char = subject_vector[start_position - 1];
+    return RawMatch(isolate, code_array, subject_string, subject_vector,
+                    registers, start_position, previous_char, call_origin,
+                    backtrack_limit);
+  } else {
+    DCHECK(subject_content.IsTwoByte());
+    Vector<const uc16> subject_vector = subject_content.ToUC16Vector();
+    if (start_position != 0) previous_char = subject_vector[start_position - 1];
+    return RawMatch(isolate, code_array, subject_string, subject_vector,
+                    registers, start_position, previous_char, call_origin,
+                    backtrack_limit);
+  }
+}
+
+// This method is called through an external reference from RegExpExecInternal
+// builtin.
+IrregexpInterpreter::Result IrregexpInterpreter::MatchForCallFromJs(
+    Address subject, int32_t start_position, Address, Address, int* registers,
+    int32_t registers_length, Address, RegExp::CallOrigin call_origin,
+    Isolate* isolate, Address regexp) {
+  DCHECK_NOT_NULL(isolate);
+  DCHECK_NOT_NULL(registers);
+  DCHECK(call_origin == RegExp::CallOrigin::kFromJs);
+
+  DisallowHeapAllocation no_gc;
+  DisallowJavascriptExecution no_js(isolate);
+
+  String subject_string = String::cast(Object(subject));
+  JSRegExp regexp_obj = JSRegExp::cast(Object(regexp));
+
+  if (regexp_obj.MarkedForTierUp()) {
+    // Returning RETRY will re-enter through runtime, where actual recompilation
+    // for tier-up takes place.
+    return IrregexpInterpreter::RETRY;
+  }
+
+  return Match(isolate, regexp_obj, subject_string, registers, registers_length,
+               start_position, call_origin);
+}
+
+IrregexpInterpreter::Result IrregexpInterpreter::MatchForCallFromRuntime(
+    Isolate* isolate, Handle<JSRegExp> regexp, Handle<String> subject_string,
+    int* registers, int registers_length, int start_position) {
+  return Match(isolate, *regexp, *subject_string, registers, registers_length,
+               start_position, RegExp::CallOrigin::kFromRuntime);
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-interpreter.h b/js/src/regexp/regexp-interpreter.h
new file mode 100644
index 0000000000..c3f6c119e8
--- /dev/null
+++ b/js/src/regexp/regexp-interpreter.h
@@ -0,0 +1,61 @@
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// A simple interpreter for the Irregexp byte code.
+
+#ifndef V8_REGEXP_REGEXP_INTERPRETER_H_
+#define V8_REGEXP_REGEXP_INTERPRETER_H_
+
+#include "regexp/regexp.h"
+
+namespace v8 {
+namespace internal {
+
+class V8_EXPORT_PRIVATE IrregexpInterpreter : public AllStatic {
+ public:
+  enum Result {
+    FAILURE = RegExp::kInternalRegExpFailure,
+    SUCCESS = RegExp::kInternalRegExpSuccess,
+    EXCEPTION = RegExp::kInternalRegExpException,
+    RETRY = RegExp::kInternalRegExpRetry,
+  };
+
+  // In case a StackOverflow occurs, a StackOverflowException is created and
+  // EXCEPTION is returned.
+  static Result MatchForCallFromRuntime(Isolate* isolate,
+                                        Handle<JSRegExp> regexp,
+                                        Handle<String> subject_string,
+                                        int* registers, int registers_length,
+                                        int start_position);
+
+  // In case a StackOverflow occurs, EXCEPTION is returned. The caller is
+  // responsible for creating the exception.
+  // RETRY is returned if a retry through the runtime is needed (e.g. when
+  // interrupts have been scheduled or the regexp is marked for tier-up).
+  // Arguments input_start, input_end and backtrack_stack are
+  // unused. They are only passed to match the signature of the native irregex
+  // code.
+  static Result MatchForCallFromJs(Address subject, int32_t start_position,
+                                   Address input_start, Address input_end,
+                                   int* registers, int32_t registers_length,
+                                   Address backtrack_stack,
+                                   RegExp::CallOrigin call_origin,
+                                   Isolate* isolate, Address regexp);
+
+  static Result MatchInternal(Isolate* isolate, ByteArray code_array,
+                              String subject_string, int* registers,
+                              int registers_length, int start_position,
+                              RegExp::CallOrigin call_origin,
+                              uint32_t backtrack_limit);
+
+ private:
+  static Result Match(Isolate* isolate, JSRegExp regexp, String subject_string,
+                      int* registers, int registers_length, int start_position,
+                      RegExp::CallOrigin call_origin);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_INTERPRETER_H_
diff --git a/js/src/regexp/regexp-macro-assembler-tracer.cc b/js/src/regexp/regexp-macro-assembler-tracer.cc
new file mode 100644
index 0000000000..331c57d1ae
--- /dev/null
+++ b/js/src/regexp/regexp-macro-assembler-tracer.cc
@@ -0,0 +1,420 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-macro-assembler-tracer.h"
+
+
+namespace v8 {
+namespace internal {
+
+RegExpMacroAssemblerTracer::RegExpMacroAssemblerTracer(
+    Isolate* isolate, RegExpMacroAssembler* assembler)
+    : RegExpMacroAssembler(isolate, assembler->zone()), assembler_(assembler) {
+  IrregexpImplementation type = assembler->Implementation();
+  DCHECK_LT(type, 9);
+  const char* impl_names[] = {"IA32", "ARM", "ARM64", "MIPS",    "S390",
+                              "PPC",  "X64", "X87",   "Bytecode"};
+  PrintF("RegExpMacroAssembler%s();\n", impl_names[type]);
+}
+
+RegExpMacroAssemblerTracer::~RegExpMacroAssemblerTracer() = default;
+
+void RegExpMacroAssemblerTracer::AbortedCodeGeneration() {
+  PrintF(" AbortedCodeGeneration\n");
+  assembler_->AbortedCodeGeneration();
+}
+
+
+// This is used for printing out debugging information.  It makes an integer
+// that is closely related to the address of an object.
+static int LabelToInt(Label* label) {
+  return static_cast<int>(reinterpret_cast<intptr_t>(label));
+}
+
+
+void RegExpMacroAssemblerTracer::Bind(Label* label) {
+  PrintF("label[%08x]: (Bind)\n", LabelToInt(label));
+  assembler_->Bind(label);
+}
+
+
+void RegExpMacroAssemblerTracer::AdvanceCurrentPosition(int by) {
+  PrintF(" AdvanceCurrentPosition(by=%d);\n", by);
+  assembler_->AdvanceCurrentPosition(by);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckGreedyLoop(Label* label) {
+  PrintF(" CheckGreedyLoop(label[%08x]);\n\n", LabelToInt(label));
+  assembler_->CheckGreedyLoop(label);
+}
+
+
+void RegExpMacroAssemblerTracer::PopCurrentPosition() {
+  PrintF(" PopCurrentPosition();\n");
+  assembler_->PopCurrentPosition();
+}
+
+
+void RegExpMacroAssemblerTracer::PushCurrentPosition() {
+  PrintF(" PushCurrentPosition();\n");
+  assembler_->PushCurrentPosition();
+}
+
+
+void RegExpMacroAssemblerTracer::Backtrack() {
+  PrintF(" Backtrack();\n");
+  assembler_->Backtrack();
+}
+
+
+void RegExpMacroAssemblerTracer::GoTo(Label* label) {
+  PrintF(" GoTo(label[%08x]);\n\n", LabelToInt(label));
+  assembler_->GoTo(label);
+}
+
+
+void RegExpMacroAssemblerTracer::PushBacktrack(Label* label) {
+  PrintF(" PushBacktrack(label[%08x]);\n", LabelToInt(label));
+  assembler_->PushBacktrack(label);
+}
+
+
+bool RegExpMacroAssemblerTracer::Succeed() {
+  bool restart = assembler_->Succeed();
+  PrintF(" Succeed();%s\n", restart ? " [restart for global match]" : "");
+  return restart;
+}
+
+
+void RegExpMacroAssemblerTracer::Fail() {
+  PrintF(" Fail();");
+  assembler_->Fail();
+}
+
+
+void RegExpMacroAssemblerTracer::PopRegister(int register_index) {
+  PrintF(" PopRegister(register=%d);\n", register_index);
+  assembler_->PopRegister(register_index);
+}
+
+
+void RegExpMacroAssemblerTracer::PushRegister(
+    int register_index,
+    StackCheckFlag check_stack_limit) {
+  PrintF(" PushRegister(register=%d, %s);\n",
+         register_index,
+         check_stack_limit ? "check stack limit" : "");
+  assembler_->PushRegister(register_index, check_stack_limit);
+}
+
+
+void RegExpMacroAssemblerTracer::AdvanceRegister(int reg, int by) {
+  PrintF(" AdvanceRegister(register=%d, by=%d);\n", reg, by);
+  assembler_->AdvanceRegister(reg, by);
+}
+
+
+void RegExpMacroAssemblerTracer::SetCurrentPositionFromEnd(int by) {
+  PrintF(" SetCurrentPositionFromEnd(by=%d);\n", by);
+  assembler_->SetCurrentPositionFromEnd(by);
+}
+
+
+void RegExpMacroAssemblerTracer::SetRegister(int register_index, int to) {
+  PrintF(" SetRegister(register=%d, to=%d);\n", register_index, to);
+  assembler_->SetRegister(register_index, to);
+}
+
+
+void RegExpMacroAssemblerTracer::WriteCurrentPositionToRegister(int reg,
+                                                                int cp_offset) {
+  PrintF(" WriteCurrentPositionToRegister(register=%d,cp_offset=%d);\n",
+         reg,
+         cp_offset);
+  assembler_->WriteCurrentPositionToRegister(reg, cp_offset);
+}
+
+
+void RegExpMacroAssemblerTracer::ClearRegisters(int reg_from, int reg_to) {
+  PrintF(" ClearRegister(from=%d, to=%d);\n", reg_from, reg_to);
+  assembler_->ClearRegisters(reg_from, reg_to);
+}
+
+
+void RegExpMacroAssemblerTracer::ReadCurrentPositionFromRegister(int reg) {
+  PrintF(" ReadCurrentPositionFromRegister(register=%d);\n", reg);
+  assembler_->ReadCurrentPositionFromRegister(reg);
+}
+
+
+void RegExpMacroAssemblerTracer::WriteStackPointerToRegister(int reg) {
+  PrintF(" WriteStackPointerToRegister(register=%d);\n", reg);
+  assembler_->WriteStackPointerToRegister(reg);
+}
+
+
+void RegExpMacroAssemblerTracer::ReadStackPointerFromRegister(int reg) {
+  PrintF(" ReadStackPointerFromRegister(register=%d);\n", reg);
+  assembler_->ReadStackPointerFromRegister(reg);
+}
+
+void RegExpMacroAssemblerTracer::LoadCurrentCharacterImpl(
+    int cp_offset, Label* on_end_of_input, bool check_bounds, int characters,
+    int eats_at_least) {
+  const char* check_msg = check_bounds ? "" : " (unchecked)";
+  PrintF(
+      " LoadCurrentCharacter(cp_offset=%d, label[%08x]%s (%d chars) (eats at "
+      "least %d));\n",
+      cp_offset, LabelToInt(on_end_of_input), check_msg, characters,
+      eats_at_least);
+  assembler_->LoadCurrentCharacter(cp_offset, on_end_of_input, check_bounds,
+                                   characters, eats_at_least);
+}
+
+class PrintablePrinter {
+ public:
+  explicit PrintablePrinter(uc16 character) : character_(character) { }
+
+  const char* operator*() {
+    if (character_ >= ' ' && character_ <= '~') {
+      buffer_[0] = '(';
+      buffer_[1] = static_cast<char>(character_);
+      buffer_[2] = ')';
+      buffer_[3] = '\0';
+    } else {
+      buffer_[0] = '\0';
+    }
+    return &buffer_[0];
+  }
+
+ private:
+  uc16 character_;
+  char buffer_[4];
+};
+
+
+void RegExpMacroAssemblerTracer::CheckCharacterLT(uc16 limit, Label* on_less) {
+  PrintablePrinter printable(limit);
+  PrintF(" CheckCharacterLT(c=0x%04x%s, label[%08x]);\n",
+         limit,
+         *printable,
+         LabelToInt(on_less));
+  assembler_->CheckCharacterLT(limit, on_less);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckCharacterGT(uc16 limit,
+                                                  Label* on_greater) {
+  PrintablePrinter printable(limit);
+  PrintF(" CheckCharacterGT(c=0x%04x%s, label[%08x]);\n",
+         limit,
+         *printable,
+         LabelToInt(on_greater));
+  assembler_->CheckCharacterGT(limit, on_greater);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckCharacter(unsigned c, Label* on_equal) {
+  PrintablePrinter printable(c);
+  PrintF(" CheckCharacter(c=0x%04x%s, label[%08x]);\n",
+         c,
+         *printable,
+         LabelToInt(on_equal));
+  assembler_->CheckCharacter(c, on_equal);
+}
+
+void RegExpMacroAssemblerTracer::CheckAtStart(int cp_offset,
+                                              Label* on_at_start) {
+  PrintF(" CheckAtStart(cp_offset=%d, label[%08x]);\n", cp_offset,
+         LabelToInt(on_at_start));
+  assembler_->CheckAtStart(cp_offset, on_at_start);
+}
+
+void RegExpMacroAssemblerTracer::CheckNotAtStart(int cp_offset,
+                                                 Label* on_not_at_start) {
+  PrintF(" CheckNotAtStart(cp_offset=%d, label[%08x]);\n", cp_offset,
+         LabelToInt(on_not_at_start));
+  assembler_->CheckNotAtStart(cp_offset, on_not_at_start);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckNotCharacter(unsigned c,
+                                                   Label* on_not_equal) {
+  PrintablePrinter printable(c);
+  PrintF(" CheckNotCharacter(c=0x%04x%s, label[%08x]);\n",
+         c,
+         *printable,
+         LabelToInt(on_not_equal));
+  assembler_->CheckNotCharacter(c, on_not_equal);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckCharacterAfterAnd(
+    unsigned c,
+    unsigned mask,
+    Label* on_equal) {
+  PrintablePrinter printable(c);
+  PrintF(" CheckCharacterAfterAnd(c=0x%04x%s, mask=0x%04x, label[%08x]);\n",
+         c,
+         *printable,
+         mask,
+         LabelToInt(on_equal));
+  assembler_->CheckCharacterAfterAnd(c, mask, on_equal);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckNotCharacterAfterAnd(
+    unsigned c,
+    unsigned mask,
+    Label* on_not_equal) {
+  PrintablePrinter printable(c);
+  PrintF(" CheckNotCharacterAfterAnd(c=0x%04x%s, mask=0x%04x, label[%08x]);\n",
+         c,
+         *printable,
+         mask,
+         LabelToInt(on_not_equal));
+  assembler_->CheckNotCharacterAfterAnd(c, mask, on_not_equal);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckNotCharacterAfterMinusAnd(
+    uc16 c,
+    uc16 minus,
+    uc16 mask,
+    Label* on_not_equal) {
+  PrintF(" CheckNotCharacterAfterMinusAnd(c=0x%04x, minus=%04x, mask=0x%04x, "
+             "label[%08x]);\n",
+         c,
+         minus,
+         mask,
+         LabelToInt(on_not_equal));
+  assembler_->CheckNotCharacterAfterMinusAnd(c, minus, mask, on_not_equal);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckCharacterInRange(
+    uc16 from,
+    uc16 to,
+    Label* on_not_in_range) {
+  PrintablePrinter printable_from(from);
+  PrintablePrinter printable_to(to);
+  PrintF(" CheckCharacterInRange(from=0x%04x%s, to=0x%04x%s, label[%08x]);\n",
+         from,
+         *printable_from,
+         to,
+         *printable_to,
+         LabelToInt(on_not_in_range));
+  assembler_->CheckCharacterInRange(from, to, on_not_in_range);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckCharacterNotInRange(
+    uc16 from,
+    uc16 to,
+    Label* on_in_range) {
+  PrintablePrinter printable_from(from);
+  PrintablePrinter printable_to(to);
+  PrintF(
+      " CheckCharacterNotInRange(from=0x%04x%s," " to=%04x%s, label[%08x]);\n",
+      from,
+      *printable_from,
+      to,
+      *printable_to,
+      LabelToInt(on_in_range));
+  assembler_->CheckCharacterNotInRange(from, to, on_in_range);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckBitInTable(
+    Handle<ByteArray> table, Label* on_bit_set) {
+  PrintF(" CheckBitInTable(label[%08x] ", LabelToInt(on_bit_set));
+  for (int i = 0; i < kTableSize; i++) {
+    PrintF("%c", table->get(i) != 0 ? 'X' : '.');
+    if (i % 32 == 31 && i != kTableMask) {
+      PrintF("\n                                 ");
+    }
+  }
+  PrintF(");\n");
+  assembler_->CheckBitInTable(table, on_bit_set);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckNotBackReference(int start_reg,
+                                                       bool read_backward,
+                                                       Label* on_no_match) {
+  PrintF(" CheckNotBackReference(register=%d, %s, label[%08x]);\n", start_reg,
+         read_backward ? "backward" : "forward", LabelToInt(on_no_match));
+  assembler_->CheckNotBackReference(start_reg, read_backward, on_no_match);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckNotBackReferenceIgnoreCase(
+    int start_reg, bool read_backward, bool unicode, Label* on_no_match) {
+  PrintF(" CheckNotBackReferenceIgnoreCase(register=%d, %s %s, label[%08x]);\n",
+         start_reg, read_backward ? "backward" : "forward",
+         unicode ? "unicode" : "non-unicode", LabelToInt(on_no_match));
+  assembler_->CheckNotBackReferenceIgnoreCase(start_reg, read_backward, unicode,
+                                              on_no_match);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckPosition(int cp_offset,
+                                               Label* on_outside_input) {
+  PrintF(" CheckPosition(cp_offset=%d, label[%08x]);\n", cp_offset,
+         LabelToInt(on_outside_input));
+  assembler_->CheckPosition(cp_offset, on_outside_input);
+}
+
+
+bool RegExpMacroAssemblerTracer::CheckSpecialCharacterClass(
+    uc16 type,
+    Label* on_no_match) {
+  bool supported = assembler_->CheckSpecialCharacterClass(type,
+                                                          on_no_match);
+  PrintF(" CheckSpecialCharacterClass(type='%c', label[%08x]): %s;\n",
+         type,
+         LabelToInt(on_no_match),
+         supported ? "true" : "false");
+  return supported;
+}
+
+
+void RegExpMacroAssemblerTracer::IfRegisterLT(int register_index,
+                                              int comparand, Label* if_lt) {
+  PrintF(" IfRegisterLT(register=%d, number=%d, label[%08x]);\n",
+         register_index, comparand, LabelToInt(if_lt));
+  assembler_->IfRegisterLT(register_index, comparand, if_lt);
+}
+
+
+void RegExpMacroAssemblerTracer::IfRegisterEqPos(int register_index,
+                                                 Label* if_eq) {
+  PrintF(" IfRegisterEqPos(register=%d, label[%08x]);\n",
+         register_index, LabelToInt(if_eq));
+  assembler_->IfRegisterEqPos(register_index, if_eq);
+}
+
+
+void RegExpMacroAssemblerTracer::IfRegisterGE(int register_index,
+                                              int comparand, Label* if_ge) {
+  PrintF(" IfRegisterGE(register=%d, number=%d, label[%08x]);\n",
+         register_index, comparand, LabelToInt(if_ge));
+  assembler_->IfRegisterGE(register_index, comparand, if_ge);
+}
+
+
+RegExpMacroAssembler::IrregexpImplementation
+    RegExpMacroAssemblerTracer::Implementation() {
+  return assembler_->Implementation();
+}
+
+
+Handle<HeapObject> RegExpMacroAssemblerTracer::GetCode(Handle<String> source) {
+  PrintF(" GetCode(%s);\n", source->ToCString().get());
+  return assembler_->GetCode(source);
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-macro-assembler-tracer.h b/js/src/regexp/regexp-macro-assembler-tracer.h
new file mode 100644
index 0000000000..938f84796d
--- /dev/null
+++ b/js/src/regexp/regexp-macro-assembler-tracer.h
@@ -0,0 +1,81 @@
+// Copyright 2008 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_MACRO_ASSEMBLER_TRACER_H_
+#define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_TRACER_H_
+
+#include "regexp/regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+// Decorator on a RegExpMacroAssembler that write all calls.
+class RegExpMacroAssemblerTracer: public RegExpMacroAssembler {
+ public:
+  RegExpMacroAssemblerTracer(Isolate* isolate, RegExpMacroAssembler* assembler);
+  ~RegExpMacroAssemblerTracer() override;
+  void AbortedCodeGeneration() override;
+  int stack_limit_slack() override { return assembler_->stack_limit_slack(); }
+  bool CanReadUnaligned() override { return assembler_->CanReadUnaligned(); }
+  void AdvanceCurrentPosition(int by) override;    // Signed cp change.
+  void AdvanceRegister(int reg, int by) override;  // r[reg] += by.
+  void Backtrack() override;
+  void Bind(Label* label) override;
+  void CheckCharacter(unsigned c, Label* on_equal) override;
+  void CheckCharacterAfterAnd(unsigned c, unsigned and_with,
+                              Label* on_equal) override;
+  void CheckCharacterGT(uc16 limit, Label* on_greater) override;
+  void CheckCharacterLT(uc16 limit, Label* on_less) override;
+  void CheckGreedyLoop(Label* on_tos_equals_current_position) override;
+  void CheckAtStart(int cp_offset, Label* on_at_start) override;
+  void CheckNotAtStart(int cp_offset, Label* on_not_at_start) override;
+  void CheckNotBackReference(int start_reg, bool read_backward,
+                             Label* on_no_match) override;
+  void CheckNotBackReferenceIgnoreCase(int start_reg, bool read_backward,
+                                       bool unicode,
+                                       Label* on_no_match) override;
+  void CheckNotCharacter(unsigned c, Label* on_not_equal) override;
+  void CheckNotCharacterAfterAnd(unsigned c, unsigned and_with,
+                                 Label* on_not_equal) override;
+  void CheckNotCharacterAfterMinusAnd(uc16 c, uc16 minus, uc16 and_with,
+                                      Label* on_not_equal) override;
+  void CheckCharacterInRange(uc16 from, uc16 to, Label* on_in_range) override;
+  void CheckCharacterNotInRange(uc16 from, uc16 to,
+                                Label* on_not_in_range) override;
+  void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set) override;
+  void CheckPosition(int cp_offset, Label* on_outside_input) override;
+  bool CheckSpecialCharacterClass(uc16 type, Label* on_no_match) override;
+  void Fail() override;
+  Handle<HeapObject> GetCode(Handle<String> source) override;
+  void GoTo(Label* label) override;
+  void IfRegisterGE(int reg, int comparand, Label* if_ge) override;
+  void IfRegisterLT(int reg, int comparand, Label* if_lt) override;
+  void IfRegisterEqPos(int reg, Label* if_eq) override;
+  IrregexpImplementation Implementation() override;
+  void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
+                                bool check_bounds, int characters,
+                                int eats_at_least) override;
+  void PopCurrentPosition() override;
+  void PopRegister(int register_index) override;
+  void PushBacktrack(Label* label) override;
+  void PushCurrentPosition() override;
+  void PushRegister(int register_index,
+                    StackCheckFlag check_stack_limit) override;
+  void ReadCurrentPositionFromRegister(int reg) override;
+  void ReadStackPointerFromRegister(int reg) override;
+  void SetCurrentPositionFromEnd(int by) override;
+  void SetRegister(int register_index, int to) override;
+  bool Succeed() override;
+  void WriteCurrentPositionToRegister(int reg, int cp_offset) override;
+  void ClearRegisters(int reg_from, int reg_to) override;
+  void WriteStackPointerToRegister(int reg) override;
+
+ private:
+  RegExpMacroAssembler* assembler_;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_TRACER_H_
diff --git a/js/src/regexp/regexp-macro-assembler.cc b/js/src/regexp/regexp-macro-assembler.cc
new file mode 100644
index 0000000000..4a8dcd3ce8
--- /dev/null
+++ b/js/src/regexp/regexp-macro-assembler.cc
@@ -0,0 +1,367 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-macro-assembler.h"
+
+#include "regexp/regexp-stack.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/uchar.h"
+#include "unicode/unistr.h"
+#endif  // V8_INTL_SUPPORT
+
+namespace v8 {
+namespace internal {
+
+RegExpMacroAssembler::RegExpMacroAssembler(Isolate* isolate, Zone* zone)
+    : slow_safe_compiler_(false),
+      global_mode_(NOT_GLOBAL),
+      isolate_(isolate),
+      zone_(zone) {}
+
+RegExpMacroAssembler::~RegExpMacroAssembler() = default;
+
+int RegExpMacroAssembler::CaseInsensitiveCompareUC16(Address byte_offset1,
+                                                     Address byte_offset2,
+                                                     size_t byte_length,
+                                                     Isolate* isolate) {
+  // This function is not allowed to cause a garbage collection.
+  // A GC might move the calling generated code and invalidate the
+  // return address on the stack.
+  DCHECK_EQ(0, byte_length % 2);
+
+#ifdef V8_INTL_SUPPORT
+  int32_t length = (int32_t)(byte_length >> 1);
+  icu::UnicodeString uni_str_1(reinterpret_cast<const char16_t*>(byte_offset1),
+                               length);
+  return uni_str_1.caseCompare(reinterpret_cast<const char16_t*>(byte_offset2),
+                               length, U_FOLD_CASE_DEFAULT) == 0;
+#else
+  uc16* substring1 = reinterpret_cast<uc16*>(byte_offset1);
+  uc16* substring2 = reinterpret_cast<uc16*>(byte_offset2);
+  size_t length = byte_length >> 1;
+  DCHECK_NOT_NULL(isolate);
+  unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize =
+      isolate->regexp_macro_assembler_canonicalize();
+  for (size_t i = 0; i < length; i++) {
+    unibrow::uchar c1 = substring1[i];
+    unibrow::uchar c2 = substring2[i];
+    if (c1 != c2) {
+      unibrow::uchar s1[1] = {c1};
+      canonicalize->get(c1, '\0', s1);
+      if (s1[0] != c2) {
+        unibrow::uchar s2[1] = {c2};
+        canonicalize->get(c2, '\0', s2);
+        if (s1[0] != s2[0]) {
+          return 0;
+        }
+      }
+    }
+  }
+  return 1;
+#endif  // V8_INTL_SUPPORT
+}
+
+
+void RegExpMacroAssembler::CheckNotInSurrogatePair(int cp_offset,
+                                                   Label* on_failure) {
+  Label ok;
+  // Check that current character is not a trail surrogate.
+  LoadCurrentCharacter(cp_offset, &ok);
+  CheckCharacterNotInRange(kTrailSurrogateStart, kTrailSurrogateEnd, &ok);
+  // Check that previous character is not a lead surrogate.
+  LoadCurrentCharacter(cp_offset - 1, &ok);
+  CheckCharacterInRange(kLeadSurrogateStart, kLeadSurrogateEnd, on_failure);
+  Bind(&ok);
+}
+
+void RegExpMacroAssembler::CheckPosition(int cp_offset,
+                                         Label* on_outside_input) {
+  LoadCurrentCharacter(cp_offset, on_outside_input, true);
+}
+
+void RegExpMacroAssembler::LoadCurrentCharacter(int cp_offset,
+                                                Label* on_end_of_input,
+                                                bool check_bounds,
+                                                int characters,
+                                                int eats_at_least) {
+  // By default, eats_at_least = characters.
+  if (eats_at_least == kUseCharactersValue) {
+    eats_at_least = characters;
+  }
+
+  LoadCurrentCharacterImpl(cp_offset, on_end_of_input, check_bounds, characters,
+                           eats_at_least);
+}
+
+bool RegExpMacroAssembler::CheckSpecialCharacterClass(uc16 type,
+                                                      Label* on_no_match) {
+  return false;
+}
+
+NativeRegExpMacroAssembler::NativeRegExpMacroAssembler(Isolate* isolate,
+                                                       Zone* zone)
+    : RegExpMacroAssembler(isolate, zone) {}
+
+NativeRegExpMacroAssembler::~NativeRegExpMacroAssembler() = default;
+
+bool NativeRegExpMacroAssembler::CanReadUnaligned() {
+  return FLAG_enable_regexp_unaligned_accesses && !slow_safe();
+}
+
+const byte* NativeRegExpMacroAssembler::StringCharacterPosition(
+    String subject, int start_index, const DisallowHeapAllocation& no_gc) {
+  if (subject.IsConsString()) {
+    subject = ConsString::cast(subject).first();
+  } else if (subject.IsSlicedString()) {
+    start_index += SlicedString::cast(subject).offset();
+    subject = SlicedString::cast(subject).parent();
+  }
+  if (subject.IsThinString()) {
+    subject = ThinString::cast(subject).actual();
+  }
+  DCHECK_LE(0, start_index);
+  DCHECK_LE(start_index, subject.length());
+  if (subject.IsSeqOneByteString()) {
+    return reinterpret_cast<const byte*>(
+        SeqOneByteString::cast(subject).GetChars(no_gc) + start_index);
+  } else if (subject.IsSeqTwoByteString()) {
+    return reinterpret_cast<const byte*>(
+        SeqTwoByteString::cast(subject).GetChars(no_gc) + start_index);
+  } else if (subject.IsExternalOneByteString()) {
+    return reinterpret_cast<const byte*>(
+        ExternalOneByteString::cast(subject).GetChars() + start_index);
+  } else {
+    DCHECK(subject.IsExternalTwoByteString());
+    return reinterpret_cast<const byte*>(
+        ExternalTwoByteString::cast(subject).GetChars() + start_index);
+  }
+}
+
+// This method may only be called after an interrupt.
+int NativeRegExpMacroAssembler::CheckStackGuardState(
+    Isolate* isolate, int start_index, RegExp::CallOrigin call_origin,
+    Address* return_address, Code re_code, Address* subject,
+    const byte** input_start, const byte** input_end) {
+  DisallowHeapAllocation no_gc;
+
+  DCHECK(re_code.raw_instruction_start() <= *return_address);
+  DCHECK(*return_address <= re_code.raw_instruction_end());
+  StackLimitCheck check(isolate);
+  bool js_has_overflowed = check.JsHasOverflowed();
+
+  if (call_origin == RegExp::CallOrigin::kFromJs) {
+    // Direct calls from JavaScript can be interrupted in two ways:
+    // 1. A real stack overflow, in which case we let the caller throw the
+    //    exception.
+    // 2. The stack guard was used to interrupt execution for another purpose,
+    //    forcing the call through the runtime system.
+
+    // Bug(v8:9540) Investigate why this method is called from JS although no
+    // stackoverflow or interrupt is pending on ARM64. We return 0 in this case
+    // to continue execution normally.
+    if (js_has_overflowed) {
+      return EXCEPTION;
+    } else if (check.InterruptRequested()) {
+      return RETRY;
+    } else {
+      return 0;
+    }
+  }
+  DCHECK(call_origin == RegExp::CallOrigin::kFromRuntime);
+
+  // Prepare for possible GC.
+  HandleScope handles(isolate);
+  Handle<Code> code_handle(re_code, isolate);
+  Handle<String> subject_handle(String::cast(Object(*subject)), isolate);
+  bool is_one_byte = String::IsOneByteRepresentationUnderneath(*subject_handle);
+  int return_value = 0;
+
+  if (js_has_overflowed) {
+    AllowHeapAllocation yes_gc;
+    isolate->StackOverflow();
+    return_value = EXCEPTION;
+  } else if (check.InterruptRequested()) {
+    AllowHeapAllocation yes_gc;
+    Object result = isolate->stack_guard()->HandleInterrupts();
+    if (result.IsException(isolate)) return_value = EXCEPTION;
+  }
+
+  if (*code_handle != re_code) {  // Return address no longer valid
+    intptr_t delta = code_handle->address() - re_code.address();
+    // Overwrite the return address on the stack.
+    *return_address += delta;
+  }
+
+  // If we continue, we need to update the subject string addresses.
+  if (return_value == 0) {
+    // String encoding might have changed.
+    if (String::IsOneByteRepresentationUnderneath(*subject_handle) !=
+        is_one_byte) {
+      // If we changed between an LATIN1 and an UC16 string, the specialized
+      // code cannot be used, and we need to restart regexp matching from
+      // scratch (including, potentially, compiling a new version of the code).
+      return_value = RETRY;
+    } else {
+      *subject = subject_handle->ptr();
+      intptr_t byte_length = *input_end - *input_start;
+      *input_start =
+          StringCharacterPosition(*subject_handle, start_index, no_gc);
+      *input_end = *input_start + byte_length;
+    }
+  }
+  return return_value;
+}
+
+// Returns a {Result} sentinel, or the number of successful matches.
+int NativeRegExpMacroAssembler::Match(Handle<JSRegExp> regexp,
+                                      Handle<String> subject,
+                                      int* offsets_vector,
+                                      int offsets_vector_length,
+                                      int previous_index, Isolate* isolate) {
+  DCHECK(subject->IsFlat());
+  DCHECK_LE(0, previous_index);
+  DCHECK_LE(previous_index, subject->length());
+
+  // No allocations before calling the regexp, but we can't use
+  // DisallowHeapAllocation, since regexps might be preempted, and another
+  // thread might do allocation anyway.
+
+  String subject_ptr = *subject;
+  // Character offsets into string.
+  int start_offset = previous_index;
+  int char_length = subject_ptr.length() - start_offset;
+  int slice_offset = 0;
+
+  // The string has been flattened, so if it is a cons string it contains the
+  // full string in the first part.
+  if (StringShape(subject_ptr).IsCons()) {
+    DCHECK_EQ(0, ConsString::cast(subject_ptr).second().length());
+    subject_ptr = ConsString::cast(subject_ptr).first();
+  } else if (StringShape(subject_ptr).IsSliced()) {
+    SlicedString slice = SlicedString::cast(subject_ptr);
+    subject_ptr = slice.parent();
+    slice_offset = slice.offset();
+  }
+  if (StringShape(subject_ptr).IsThin()) {
+    subject_ptr = ThinString::cast(subject_ptr).actual();
+  }
+  // Ensure that an underlying string has the same representation.
+  bool is_one_byte = subject_ptr.IsOneByteRepresentation();
+  DCHECK(subject_ptr.IsExternalString() || subject_ptr.IsSeqString());
+  // String is now either Sequential or External
+  int char_size_shift = is_one_byte ? 0 : 1;
+
+  DisallowHeapAllocation no_gc;
+  const byte* input_start =
+      StringCharacterPosition(subject_ptr, start_offset + slice_offset, no_gc);
+  int byte_length = char_length << char_size_shift;
+  const byte* input_end = input_start + byte_length;
+  return Execute(*subject, start_offset, input_start, input_end, offsets_vector,
+                 offsets_vector_length, isolate, *regexp);
+}
+
+// Returns a {Result} sentinel, or the number of successful matches.
+// TODO(pthier): The JSRegExp object is passed to native irregexp code to match
+// the signature of the interpreter. We should get rid of JS objects passed to
+// internal methods.
+int NativeRegExpMacroAssembler::Execute(
+    String input,  // This needs to be the unpacked (sliced, cons) string.
+    int start_offset, const byte* input_start, const byte* input_end,
+    int* output, int output_size, Isolate* isolate, JSRegExp regexp) {
+  // Ensure that the minimum stack has been allocated.
+  RegExpStackScope stack_scope(isolate);
+  Address stack_base = stack_scope.stack()->stack_base();
+
+  bool is_one_byte = String::IsOneByteRepresentationUnderneath(input);
+  Code code = Code::cast(regexp.Code(is_one_byte));
+  RegExp::CallOrigin call_origin = RegExp::CallOrigin::kFromRuntime;
+
+  using RegexpMatcherSig = int(
+      Address input_string, int start_offset,  // NOLINT(readability/casting)
+      const byte* input_start, const byte* input_end, int* output,
+      int output_size, Address stack_base, int call_origin, Isolate* isolate,
+      Address regexp);
+
+  auto fn = GeneratedCode<RegexpMatcherSig>::FromCode(code);
+  int result =
+      fn.Call(input.ptr(), start_offset, input_start, input_end, output,
+              output_size, stack_base, call_origin, isolate, regexp.ptr());
+  DCHECK(result >= RETRY);
+
+  if (result == EXCEPTION && !isolate->has_pending_exception()) {
+    // We detected a stack overflow (on the backtrack stack) in RegExp code,
+    // but haven't created the exception yet. Additionally, we allow heap
+    // allocation because even though it invalidates {input_start} and
+    // {input_end}, we are about to return anyway.
+    AllowHeapAllocation allow_allocation;
+    isolate->StackOverflow();
+  }
+  return result;
+}
+
+// clang-format off
+const byte NativeRegExpMacroAssembler::word_character_map[] = {
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // '0' - '7'
+    0xFFu, 0xFFu, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,  // '8' - '9'
+
+    0x00u, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'A' - 'G'
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'H' - 'O'
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'P' - 'W'
+    0xFFu, 0xFFu, 0xFFu, 0x00u, 0x00u, 0x00u, 0x00u, 0xFFu,  // 'X' - 'Z', '_'
+
+    0x00u, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'a' - 'g'
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'h' - 'o'
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'p' - 'w'
+    0xFFu, 0xFFu, 0xFFu, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,  // 'x' - 'z'
+    // Latin-1 range
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+};
+// clang-format on
+
+Address NativeRegExpMacroAssembler::GrowStack(Address stack_pointer,
+                                              Address* stack_base,
+                                              Isolate* isolate) {
+  RegExpStack* regexp_stack = isolate->regexp_stack();
+  size_t size = regexp_stack->stack_capacity();
+  Address old_stack_base = regexp_stack->stack_base();
+  DCHECK(old_stack_base == *stack_base);
+  DCHECK(stack_pointer <= old_stack_base);
+  DCHECK(static_cast<size_t>(old_stack_base - stack_pointer) <= size);
+  Address new_stack_base = regexp_stack->EnsureCapacity(size * 2);
+  if (new_stack_base == kNullAddress) {
+    return kNullAddress;
+  }
+  *stack_base = new_stack_base;
+  intptr_t stack_content_size = old_stack_base - stack_pointer;
+  return new_stack_base - stack_content_size;
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-macro-assembler.h b/js/src/regexp/regexp-macro-assembler.h
new file mode 100644
index 0000000000..67d97d1228
--- /dev/null
+++ b/js/src/regexp/regexp-macro-assembler.h
@@ -0,0 +1,277 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
+#define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
+
+#include "regexp/regexp-ast.h"
+#include "regexp/regexp.h"
+
+namespace v8 {
+namespace internal {
+
+static const uc32 kLeadSurrogateStart = 0xd800;
+static const uc32 kLeadSurrogateEnd = 0xdbff;
+static const uc32 kTrailSurrogateStart = 0xdc00;
+static const uc32 kTrailSurrogateEnd = 0xdfff;
+static const uc32 kNonBmpStart = 0x10000;
+static const uc32 kNonBmpEnd = 0x10ffff;
+
+struct DisjunctDecisionRow {
+  RegExpCharacterClass cc;
+  Label* on_match;
+};
+
+
+class RegExpMacroAssembler {
+ public:
+  // The implementation must be able to handle at least:
+  static const int kMaxRegister = (1 << 16) - 1;
+  static const int kMaxCPOffset = (1 << 15) - 1;
+  static const int kMinCPOffset = -(1 << 15);
+
+  static const int kTableSizeBits = 7;
+  static const int kTableSize = 1 << kTableSizeBits;
+  static const int kTableMask = kTableSize - 1;
+
+  static constexpr int kUseCharactersValue = -1;
+
+  enum IrregexpImplementation {
+    kIA32Implementation,
+    kARMImplementation,
+    kARM64Implementation,
+    kMIPSImplementation,
+    kS390Implementation,
+    kPPCImplementation,
+    kX64Implementation,
+    kX87Implementation,
+    kBytecodeImplementation
+  };
+
+  enum StackCheckFlag {
+    kNoStackLimitCheck = false,
+    kCheckStackLimit = true
+  };
+
+  RegExpMacroAssembler(Isolate* isolate, Zone* zone);
+  virtual ~RegExpMacroAssembler();
+  // This function is called when code generation is aborted, so that
+  // the assembler could clean up internal data structures.
+  virtual void AbortedCodeGeneration() {}
+  // The maximal number of pushes between stack checks. Users must supply
+  // kCheckStackLimit flag to push operations (instead of kNoStackLimitCheck)
+  // at least once for every stack_limit() pushes that are executed.
+  virtual int stack_limit_slack() = 0;
+  virtual bool CanReadUnaligned() = 0;
+  virtual void AdvanceCurrentPosition(int by) = 0;  // Signed cp change.
+  virtual void AdvanceRegister(int reg, int by) = 0;  // r[reg] += by.
+  // Continues execution from the position pushed on the top of the backtrack
+  // stack by an earlier PushBacktrack(Label*).
+  virtual void Backtrack() = 0;
+  virtual void Bind(Label* label) = 0;
+  // Dispatch after looking the current character up in a 2-bits-per-entry
+  // map.  The destinations vector has up to 4 labels.
+  virtual void CheckCharacter(unsigned c, Label* on_equal) = 0;
+  // Bitwise and the current character with the given constant and then
+  // check for a match with c.
+  virtual void CheckCharacterAfterAnd(unsigned c,
+                                      unsigned and_with,
+                                      Label* on_equal) = 0;
+  virtual void CheckCharacterGT(uc16 limit, Label* on_greater) = 0;
+  virtual void CheckCharacterLT(uc16 limit, Label* on_less) = 0;
+  virtual void CheckGreedyLoop(Label* on_tos_equals_current_position) = 0;
+  virtual void CheckAtStart(int cp_offset, Label* on_at_start) = 0;
+  virtual void CheckNotAtStart(int cp_offset, Label* on_not_at_start) = 0;
+  virtual void CheckNotBackReference(int start_reg, bool read_backward,
+                                     Label* on_no_match) = 0;
+  virtual void CheckNotBackReferenceIgnoreCase(int start_reg,
+                                               bool read_backward, bool unicode,
+                                               Label* on_no_match) = 0;
+  // Check the current character for a match with a literal character.  If we
+  // fail to match then goto the on_failure label.  End of input always
+  // matches.  If the label is nullptr then we should pop a backtrack address
+  // off the stack and go to that.
+  virtual void CheckNotCharacter(unsigned c, Label* on_not_equal) = 0;
+  virtual void CheckNotCharacterAfterAnd(unsigned c,
+                                         unsigned and_with,
+                                         Label* on_not_equal) = 0;
+  // Subtract a constant from the current character, then and with the given
+  // constant and then check for a match with c.
+  virtual void CheckNotCharacterAfterMinusAnd(uc16 c,
+                                              uc16 minus,
+                                              uc16 and_with,
+                                              Label* on_not_equal) = 0;
+  virtual void CheckCharacterInRange(uc16 from,
+                                     uc16 to,  // Both inclusive.
+                                     Label* on_in_range) = 0;
+  virtual void CheckCharacterNotInRange(uc16 from,
+                                        uc16 to,  // Both inclusive.
+                                        Label* on_not_in_range) = 0;
+
+  // The current character (modulus the kTableSize) is looked up in the byte
+  // array, and if the found byte is non-zero, we jump to the on_bit_set label.
+  virtual void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set) = 0;
+
+  // Checks whether the given offset from the current position is before
+  // the end of the string.  May overwrite the current character.
+  virtual void CheckPosition(int cp_offset, Label* on_outside_input);
+  // Check whether a standard/default character class matches the current
+  // character. Returns false if the type of special character class does
+  // not have custom support.
+  // May clobber the current loaded character.
+  virtual bool CheckSpecialCharacterClass(uc16 type, Label* on_no_match);
+  virtual void Fail() = 0;
+  virtual Handle<HeapObject> GetCode(Handle<String> source) = 0;
+  virtual void GoTo(Label* label) = 0;
+  // Check whether a register is >= a given constant and go to a label if it
+  // is.  Backtracks instead if the label is nullptr.
+  virtual void IfRegisterGE(int reg, int comparand, Label* if_ge) = 0;
+  // Check whether a register is < a given constant and go to a label if it is.
+  // Backtracks instead if the label is nullptr.
+  virtual void IfRegisterLT(int reg, int comparand, Label* if_lt) = 0;
+  // Check whether a register is == to the current position and go to a
+  // label if it is.
+  virtual void IfRegisterEqPos(int reg, Label* if_eq) = 0;
+  virtual IrregexpImplementation Implementation() = 0;
+  V8_EXPORT_PRIVATE void LoadCurrentCharacter(
+      int cp_offset, Label* on_end_of_input, bool check_bounds = true,
+      int characters = 1, int eats_at_least = kUseCharactersValue);
+  virtual void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
+                                        bool check_bounds, int characters,
+                                        int eats_at_least) = 0;
+  virtual void PopCurrentPosition() = 0;
+  virtual void PopRegister(int register_index) = 0;
+  // Pushes the label on the backtrack stack, so that a following Backtrack
+  // will go to this label. Always checks the backtrack stack limit.
+  virtual void PushBacktrack(Label* label) = 0;
+  virtual void PushCurrentPosition() = 0;
+  virtual void PushRegister(int register_index,
+                            StackCheckFlag check_stack_limit) = 0;
+  virtual void ReadCurrentPositionFromRegister(int reg) = 0;
+  virtual void ReadStackPointerFromRegister(int reg) = 0;
+  virtual void SetCurrentPositionFromEnd(int by) = 0;
+  virtual void SetRegister(int register_index, int to) = 0;
+  // Return whether the matching (with a global regexp) will be restarted.
+  virtual bool Succeed() = 0;
+  virtual void WriteCurrentPositionToRegister(int reg, int cp_offset) = 0;
+  virtual void ClearRegisters(int reg_from, int reg_to) = 0;
+  virtual void WriteStackPointerToRegister(int reg) = 0;
+
+  // Compares two-byte strings case insensitively.
+  // Called from generated RegExp code.
+  static int CaseInsensitiveCompareUC16(Address byte_offset1,
+                                        Address byte_offset2,
+                                        size_t byte_length, Isolate* isolate);
+
+  // Check that we are not in the middle of a surrogate pair.
+  void CheckNotInSurrogatePair(int cp_offset, Label* on_failure);
+
+  // Controls the generation of large inlined constants in the code.
+  void set_slow_safe(bool ssc) { slow_safe_compiler_ = ssc; }
+  bool slow_safe() { return slow_safe_compiler_; }
+
+  void set_backtrack_limit(uint32_t backtrack_limit) {
+    backtrack_limit_ = backtrack_limit;
+  }
+
+  enum GlobalMode {
+    NOT_GLOBAL,
+    GLOBAL_NO_ZERO_LENGTH_CHECK,
+    GLOBAL,
+    GLOBAL_UNICODE
+  };
+  // Set whether the regular expression has the global flag.  Exiting due to
+  // a failure in a global regexp may still mean success overall.
+  inline void set_global_mode(GlobalMode mode) { global_mode_ = mode; }
+  inline bool global() { return global_mode_ != NOT_GLOBAL; }
+  inline bool global_with_zero_length_check() {
+    return global_mode_ == GLOBAL || global_mode_ == GLOBAL_UNICODE;
+  }
+  inline bool global_unicode() { return global_mode_ == GLOBAL_UNICODE; }
+
+  Isolate* isolate() const { return isolate_; }
+  Zone* zone() const { return zone_; }
+
+ protected:
+  bool has_backtrack_limit() const {
+    return backtrack_limit_ != JSRegExp::kNoBacktrackLimit;
+  }
+  uint32_t backtrack_limit() const { return backtrack_limit_; }
+
+ private:
+  bool slow_safe_compiler_;
+  uint32_t backtrack_limit_ = JSRegExp::kNoBacktrackLimit;
+  GlobalMode global_mode_;
+  Isolate* isolate_;
+  Zone* zone_;
+};
+
+class NativeRegExpMacroAssembler: public RegExpMacroAssembler {
+ public:
+  // Type of input string to generate code for.
+  enum Mode { LATIN1 = 1, UC16 = 2 };
+
+  // Result of calling generated native RegExp code.
+  // RETRY: Something significant changed during execution, and the matching
+  //        should be retried from scratch.
+  // EXCEPTION: Something failed during execution. If no exception has been
+  //        thrown, it's an internal out-of-memory, and the caller should
+  //        throw the exception.
+  // FAILURE: Matching failed.
+  // SUCCESS: Matching succeeded, and the output array has been filled with
+  //        capture positions.
+  enum Result {
+    FAILURE = RegExp::kInternalRegExpFailure,
+    SUCCESS = RegExp::kInternalRegExpSuccess,
+    EXCEPTION = RegExp::kInternalRegExpException,
+    RETRY = RegExp::kInternalRegExpRetry,
+  };
+
+  NativeRegExpMacroAssembler(Isolate* isolate, Zone* zone);
+  ~NativeRegExpMacroAssembler() override;
+  bool CanReadUnaligned() override;
+
+  // Returns a {Result} sentinel, or the number of successful matches.
+  static int Match(Handle<JSRegExp> regexp, Handle<String> subject,
+                   int* offsets_vector, int offsets_vector_length,
+                   int previous_index, Isolate* isolate);
+
+  // Called from RegExp if the backtrack stack limit is hit.
+  // Tries to expand the stack. Returns the new stack-pointer if
+  // successful, and updates the stack_top address, or returns 0 if unable
+  // to grow the stack.
+  // This function must not trigger a garbage collection.
+  static Address GrowStack(Address stack_pointer, Address* stack_top,
+                           Isolate* isolate);
+
+  static const byte* StringCharacterPosition(
+      String subject, int start_index, const DisallowHeapAllocation& no_gc);
+
+  static int CheckStackGuardState(Isolate* isolate, int start_index,
+                                  RegExp::CallOrigin call_origin,
+                                  Address* return_address, Code re_code,
+                                  Address* subject, const byte** input_start,
+                                  const byte** input_end);
+
+  // Byte map of one byte characters with a 0xff if the character is a word
+  // character (digit, letter or underscore) and 0x00 otherwise.
+  // Used by generated RegExp code.
+  static const byte word_character_map[256];
+
+  static Address word_character_map_address() {
+    return reinterpret_cast<Address>(&word_character_map[0]);
+  }
+
+  // Returns a {Result} sentinel, or the number of successful matches.
+  V8_EXPORT_PRIVATE static int Execute(String input, int start_offset,
+                                       const byte* input_start,
+                                       const byte* input_end, int* output,
+                                       int output_size, Isolate* isolate,
+                                       JSRegExp regexp);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
diff --git a/js/src/regexp/regexp-nodes.h b/js/src/regexp/regexp-nodes.h
new file mode 100644
index 0000000000..50c843c20c
--- /dev/null
+++ b/js/src/regexp/regexp-nodes.h
@@ -0,0 +1,750 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_NODES_H_
+#define V8_REGEXP_REGEXP_NODES_H_
+
+#include "regexp/regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+class AlternativeGenerationList;
+class BoyerMooreLookahead;
+class GreedyLoopState;
+class Label;
+class NodeVisitor;
+class QuickCheckDetails;
+class RegExpCompiler;
+class Trace;
+struct PreloadState;
+class ChoiceNode;
+
+#define FOR_EACH_NODE_TYPE(VISIT) \
+  VISIT(End)                      \
+  VISIT(Action)                   \
+  VISIT(Choice)                   \
+  VISIT(LoopChoice)               \
+  VISIT(NegativeLookaroundChoice) \
+  VISIT(BackReference)            \
+  VISIT(Assertion)                \
+  VISIT(Text)
+
+struct NodeInfo final {
+  NodeInfo()
+      : being_analyzed(false),
+        been_analyzed(false),
+        follows_word_interest(false),
+        follows_newline_interest(false),
+        follows_start_interest(false),
+        at_end(false),
+        visited(false),
+        replacement_calculated(false) {}
+
+  // Returns true if the interests and assumptions of this node
+  // matches the given one.
+  bool Matches(NodeInfo* that) {
+    return (at_end == that->at_end) &&
+           (follows_word_interest == that->follows_word_interest) &&
+           (follows_newline_interest == that->follows_newline_interest) &&
+           (follows_start_interest == that->follows_start_interest);
+  }
+
+  // Updates the interests of this node given the interests of the
+  // node preceding it.
+  void AddFromPreceding(NodeInfo* that) {
+    at_end |= that->at_end;
+    follows_word_interest |= that->follows_word_interest;
+    follows_newline_interest |= that->follows_newline_interest;
+    follows_start_interest |= that->follows_start_interest;
+  }
+
+  bool HasLookbehind() {
+    return follows_word_interest || follows_newline_interest ||
+           follows_start_interest;
+  }
+
+  // Sets the interests of this node to include the interests of the
+  // following node.
+  void AddFromFollowing(NodeInfo* that) {
+    follows_word_interest |= that->follows_word_interest;
+    follows_newline_interest |= that->follows_newline_interest;
+    follows_start_interest |= that->follows_start_interest;
+  }
+
+  void ResetCompilationState() {
+    being_analyzed = false;
+    been_analyzed = false;
+  }
+
+  bool being_analyzed : 1;
+  bool been_analyzed : 1;
+
+  // These bits are set of this node has to know what the preceding
+  // character was.
+  bool follows_word_interest : 1;
+  bool follows_newline_interest : 1;
+  bool follows_start_interest : 1;
+
+  bool at_end : 1;
+  bool visited : 1;
+  bool replacement_calculated : 1;
+};
+
+struct EatsAtLeastInfo final {
+  EatsAtLeastInfo() : EatsAtLeastInfo(0) {}
+  explicit EatsAtLeastInfo(uint8_t eats)
+      : eats_at_least_from_possibly_start(eats),
+        eats_at_least_from_not_start(eats) {}
+  void SetMin(const EatsAtLeastInfo& other) {
+    if (other.eats_at_least_from_possibly_start <
+        eats_at_least_from_possibly_start) {
+      eats_at_least_from_possibly_start =
+          other.eats_at_least_from_possibly_start;
+    }
+    if (other.eats_at_least_from_not_start < eats_at_least_from_not_start) {
+      eats_at_least_from_not_start = other.eats_at_least_from_not_start;
+    }
+  }
+
+  // Any successful match starting from the current node will consume at least
+  // this many characters. This does not necessarily mean that there is a
+  // possible match with exactly this many characters, but we generally try to
+  // get this number as high as possible to allow for early exit on failure.
+  uint8_t eats_at_least_from_possibly_start;
+
+  // Like eats_at_least_from_possibly_start, but with the additional assumption
+  // that start-of-string assertions (^) can't match. This value is greater than
+  // or equal to eats_at_least_from_possibly_start.
+  uint8_t eats_at_least_from_not_start;
+};
+
+class RegExpNode : public ZoneObject {
+ public:
+  explicit RegExpNode(Zone* zone)
+      : replacement_(nullptr),
+        on_work_list_(false),
+        trace_count_(0),
+        zone_(zone) {
+    bm_info_[0] = bm_info_[1] = nullptr;
+  }
+  virtual ~RegExpNode();
+  virtual void Accept(NodeVisitor* visitor) = 0;
+  // Generates a goto to this node or actually generates the code at this point.
+  virtual void Emit(RegExpCompiler* compiler, Trace* trace) = 0;
+  // How many characters must this node consume at a minimum in order to
+  // succeed.  The not_at_start argument is used to indicate that we know we are
+  // not at the start of the input.  In this case anchored branches will always
+  // fail and can be ignored when determining how many characters are consumed
+  // on success.  If this node has not been analyzed yet, EatsAtLeast returns 0.
+  int EatsAtLeast(bool not_at_start);
+  // Returns how many characters this node must consume in order to succeed,
+  // given that this is a LoopChoiceNode whose counter register is in a
+  // newly-initialized state at the current position in the generated code. For
+  // example, consider /a{6,8}/. Absent any extra information, the
+  // LoopChoiceNode for the repetition must report that it consumes at least
+  // zero characters, because it may have already looped several times. However,
+  // with a newly-initialized counter, it can report that it consumes at least
+  // six characters.
+  virtual EatsAtLeastInfo EatsAtLeastFromLoopEntry();
+  // Emits some quick code that checks whether the preloaded characters match.
+  // Falls through on certain failure, jumps to the label on possible success.
+  // If the node cannot make a quick check it does nothing and returns false.
+  bool EmitQuickCheck(RegExpCompiler* compiler, Trace* bounds_check_trace,
+                      Trace* trace, bool preload_has_checked_bounds,
+                      Label* on_possible_success,
+                      QuickCheckDetails* details_return,
+                      bool fall_through_on_failure, ChoiceNode* predecessor);
+  // For a given number of characters this returns a mask and a value.  The
+  // next n characters are anded with the mask and compared with the value.
+  // A comparison failure indicates the node cannot match the next n characters.
+  // A comparison success indicates the node may match.
+  virtual void GetQuickCheckDetails(QuickCheckDetails* details,
+                                    RegExpCompiler* compiler,
+                                    int characters_filled_in,
+                                    bool not_at_start) = 0;
+  // Fills in quick check details for this node, given that this is a
+  // LoopChoiceNode whose counter register is in a newly-initialized state at
+  // the current position in the generated code. For example, consider /a{6,8}/.
+  // Absent any extra information, the LoopChoiceNode for the repetition cannot
+  // generate any useful quick check because a match might be the (empty)
+  // continuation node. However, with a newly-initialized counter, it can
+  // generate a quick check for several 'a' characters at once.
+  virtual void GetQuickCheckDetailsFromLoopEntry(QuickCheckDetails* details,
+                                                 RegExpCompiler* compiler,
+                                                 int characters_filled_in,
+                                                 bool not_at_start);
+  static const int kNodeIsTooComplexForGreedyLoops = kMinInt;
+  virtual int GreedyLoopTextLength() { return kNodeIsTooComplexForGreedyLoops; }
+  // Only returns the successor for a text node of length 1 that matches any
+  // character and that has no guards on it.
+  virtual RegExpNode* GetSuccessorOfOmnivorousTextNode(
+      RegExpCompiler* compiler) {
+    return nullptr;
+  }
+
+  // Collects information on the possible code units (mod 128) that can match if
+  // we look forward.  This is used for a Boyer-Moore-like string searching
+  // implementation.  TODO(erikcorry):  This should share more code with
+  // EatsAtLeast, GetQuickCheckDetails.  The budget argument is used to limit
+  // the number of nodes we are willing to look at in order to create this data.
+  static const int kRecursionBudget = 200;
+  bool KeepRecursing(RegExpCompiler* compiler);
+  virtual void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                            BoyerMooreLookahead* bm, bool not_at_start) {
+    UNREACHABLE();
+  }
+
+  // If we know that the input is one-byte then there are some nodes that can
+  // never match.  This method returns a node that can be substituted for
+  // itself, or nullptr if the node can never match.
+  virtual RegExpNode* FilterOneByte(int depth) { return this; }
+  // Helper for FilterOneByte.
+  RegExpNode* replacement() {
+    DCHECK(info()->replacement_calculated);
+    return replacement_;
+  }
+  RegExpNode* set_replacement(RegExpNode* replacement) {
+    info()->replacement_calculated = true;
+    replacement_ = replacement;
+    return replacement;  // For convenience.
+  }
+
+  // We want to avoid recalculating the lookahead info, so we store it on the
+  // node.  Only info that is for this node is stored.  We can tell that the
+  // info is for this node when offset == 0, so the information is calculated
+  // relative to this node.
+  void SaveBMInfo(BoyerMooreLookahead* bm, bool not_at_start, int offset) {
+    if (offset == 0) set_bm_info(not_at_start, bm);
+  }
+
+  Label* label() { return &label_; }
+  // If non-generic code is generated for a node (i.e. the node is not at the
+  // start of the trace) then it cannot be reused.  This variable sets a limit
+  // on how often we allow that to happen before we insist on starting a new
+  // trace and generating generic code for a node that can be reused by flushing
+  // the deferred actions in the current trace and generating a goto.
+  static const int kMaxCopiesCodeGenerated = 10;
+
+  bool on_work_list() { return on_work_list_; }
+  void set_on_work_list(bool value) { on_work_list_ = value; }
+
+  NodeInfo* info() { return &info_; }
+  const EatsAtLeastInfo* eats_at_least_info() const { return &eats_at_least_; }
+  void set_eats_at_least_info(const EatsAtLeastInfo& eats_at_least) {
+    eats_at_least_ = eats_at_least;
+  }
+
+  BoyerMooreLookahead* bm_info(bool not_at_start) {
+    return bm_info_[not_at_start ? 1 : 0];
+  }
+
+  Zone* zone() const { return zone_; }
+
+ protected:
+  enum LimitResult { DONE, CONTINUE };
+  RegExpNode* replacement_;
+
+  LimitResult LimitVersions(RegExpCompiler* compiler, Trace* trace);
+
+  void set_bm_info(bool not_at_start, BoyerMooreLookahead* bm) {
+    bm_info_[not_at_start ? 1 : 0] = bm;
+  }
+
+ private:
+  static const int kFirstCharBudget = 10;
+  Label label_;
+  bool on_work_list_;
+  NodeInfo info_;
+
+  // Saved values for EatsAtLeast results, to avoid recomputation. Filled in
+  // during analysis (valid if info_.been_analyzed is true).
+  EatsAtLeastInfo eats_at_least_;
+
+  // This variable keeps track of how many times code has been generated for
+  // this node (in different traces).  We don't keep track of where the
+  // generated code is located unless the code is generated at the start of
+  // a trace, in which case it is generic and can be reused by flushing the
+  // deferred operations in the current trace and generating a goto.
+  int trace_count_;
+  BoyerMooreLookahead* bm_info_[2];
+
+  Zone* zone_;
+};
+
+class SeqRegExpNode : public RegExpNode {
+ public:
+  explicit SeqRegExpNode(RegExpNode* on_success)
+      : RegExpNode(on_success->zone()), on_success_(on_success) {}
+  RegExpNode* on_success() { return on_success_; }
+  void set_on_success(RegExpNode* node) { on_success_ = node; }
+  RegExpNode* FilterOneByte(int depth) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override {
+    on_success_->FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
+    if (offset == 0) set_bm_info(not_at_start, bm);
+  }
+
+ protected:
+  RegExpNode* FilterSuccessor(int depth);
+
+ private:
+  RegExpNode* on_success_;
+};
+
+class ActionNode : public SeqRegExpNode {
+ public:
+  enum ActionType {
+    SET_REGISTER_FOR_LOOP,
+    INCREMENT_REGISTER,
+    STORE_POSITION,
+    BEGIN_SUBMATCH,
+    POSITIVE_SUBMATCH_SUCCESS,
+    EMPTY_MATCH_CHECK,
+    CLEAR_CAPTURES
+  };
+  static ActionNode* SetRegisterForLoop(int reg, int val,
+                                        RegExpNode* on_success);
+  static ActionNode* IncrementRegister(int reg, RegExpNode* on_success);
+  static ActionNode* StorePosition(int reg, bool is_capture,
+                                   RegExpNode* on_success);
+  static ActionNode* ClearCaptures(Interval range, RegExpNode* on_success);
+  static ActionNode* BeginSubmatch(int stack_pointer_reg, int position_reg,
+                                   RegExpNode* on_success);
+  static ActionNode* PositiveSubmatchSuccess(int stack_pointer_reg,
+                                             int restore_reg,
+                                             int clear_capture_count,
+                                             int clear_capture_from,
+                                             RegExpNode* on_success);
+  static ActionNode* EmptyMatchCheck(int start_register,
+                                     int repetition_register,
+                                     int repetition_limit,
+                                     RegExpNode* on_success);
+  void Accept(NodeVisitor* visitor) override;
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int filled_in,
+                            bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+  ActionType action_type() { return action_type_; }
+  // TODO(erikcorry): We should allow some action nodes in greedy loops.
+  int GreedyLoopTextLength() override {
+    return kNodeIsTooComplexForGreedyLoops;
+  }
+
+ private:
+  union {
+    struct {
+      int reg;
+      int value;
+    } u_store_register;
+    struct {
+      int reg;
+    } u_increment_register;
+    struct {
+      int reg;
+      bool is_capture;
+    } u_position_register;
+    struct {
+      int stack_pointer_register;
+      int current_position_register;
+      int clear_register_count;
+      int clear_register_from;
+    } u_submatch;
+    struct {
+      int start_register;
+      int repetition_register;
+      int repetition_limit;
+    } u_empty_match_check;
+    struct {
+      int range_from;
+      int range_to;
+    } u_clear_captures;
+  } data_;
+  ActionNode(ActionType action_type, RegExpNode* on_success)
+      : SeqRegExpNode(on_success), action_type_(action_type) {}
+  ActionType action_type_;
+  friend class DotPrinterImpl;
+};
+
+class TextNode : public SeqRegExpNode {
+ public:
+  TextNode(ZoneList<TextElement>* elms, bool read_backward,
+           RegExpNode* on_success)
+      : SeqRegExpNode(on_success), elms_(elms), read_backward_(read_backward) {}
+  TextNode(RegExpCharacterClass* that, bool read_backward,
+           RegExpNode* on_success)
+      : SeqRegExpNode(on_success),
+        elms_(new (zone()) ZoneList<TextElement>(1, zone())),
+        read_backward_(read_backward) {
+    elms_->Add(TextElement::CharClass(that), zone());
+  }
+  // Create TextNode for a single character class for the given ranges.
+  static TextNode* CreateForCharacterRanges(Zone* zone,
+                                            ZoneList<CharacterRange>* ranges,
+                                            bool read_backward,
+                                            RegExpNode* on_success,
+                                            JSRegExp::Flags flags);
+  // Create TextNode for a surrogate pair with a range given for the
+  // lead and the trail surrogate each.
+  static TextNode* CreateForSurrogatePair(Zone* zone, CharacterRange lead,
+                                          CharacterRange trail,
+                                          bool read_backward,
+                                          RegExpNode* on_success,
+                                          JSRegExp::Flags flags);
+  void Accept(NodeVisitor* visitor) override;
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override;
+  ZoneList<TextElement>* elements() { return elms_; }
+  bool read_backward() { return read_backward_; }
+  void MakeCaseIndependent(Isolate* isolate, bool is_one_byte);
+  int GreedyLoopTextLength() override;
+  RegExpNode* GetSuccessorOfOmnivorousTextNode(
+      RegExpCompiler* compiler) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+  void CalculateOffsets();
+  RegExpNode* FilterOneByte(int depth) override;
+  int Length();
+
+ private:
+  enum TextEmitPassType {
+    NON_LATIN1_MATCH,            // Check for characters that can't match.
+    SIMPLE_CHARACTER_MATCH,      // Case-dependent single character check.
+    NON_LETTER_CHARACTER_MATCH,  // Check characters that have no case equivs.
+    CASE_CHARACTER_MATCH,        // Case-independent single character check.
+    CHARACTER_CLASS_MATCH        // Character class.
+  };
+  static bool SkipPass(TextEmitPassType pass, bool ignore_case);
+  static const int kFirstRealPass = SIMPLE_CHARACTER_MATCH;
+  static const int kLastPass = CHARACTER_CLASS_MATCH;
+  void TextEmitPass(RegExpCompiler* compiler, TextEmitPassType pass,
+                    bool preloaded, Trace* trace, bool first_element_checked,
+                    int* checked_up_to);
+  ZoneList<TextElement>* elms_;
+  bool read_backward_;
+};
+
+class AssertionNode : public SeqRegExpNode {
+ public:
+  enum AssertionType {
+    AT_END,
+    AT_START,
+    AT_BOUNDARY,
+    AT_NON_BOUNDARY,
+    AFTER_NEWLINE
+  };
+  static AssertionNode* AtEnd(RegExpNode* on_success) {
+    return new (on_success->zone()) AssertionNode(AT_END, on_success);
+  }
+  static AssertionNode* AtStart(RegExpNode* on_success) {
+    return new (on_success->zone()) AssertionNode(AT_START, on_success);
+  }
+  static AssertionNode* AtBoundary(RegExpNode* on_success) {
+    return new (on_success->zone()) AssertionNode(AT_BOUNDARY, on_success);
+  }
+  static AssertionNode* AtNonBoundary(RegExpNode* on_success) {
+    return new (on_success->zone()) AssertionNode(AT_NON_BOUNDARY, on_success);
+  }
+  static AssertionNode* AfterNewline(RegExpNode* on_success) {
+    return new (on_success->zone()) AssertionNode(AFTER_NEWLINE, on_success);
+  }
+  void Accept(NodeVisitor* visitor) override;
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int filled_in,
+                            bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+  AssertionType assertion_type() { return assertion_type_; }
+
+ private:
+  void EmitBoundaryCheck(RegExpCompiler* compiler, Trace* trace);
+  enum IfPrevious { kIsNonWord, kIsWord };
+  void BacktrackIfPrevious(RegExpCompiler* compiler, Trace* trace,
+                           IfPrevious backtrack_if_previous);
+  AssertionNode(AssertionType t, RegExpNode* on_success)
+      : SeqRegExpNode(on_success), assertion_type_(t) {}
+  AssertionType assertion_type_;
+};
+
+class BackReferenceNode : public SeqRegExpNode {
+ public:
+  BackReferenceNode(int start_reg, int end_reg, JSRegExp::Flags flags,
+                    bool read_backward, RegExpNode* on_success)
+      : SeqRegExpNode(on_success),
+        start_reg_(start_reg),
+        end_reg_(end_reg),
+        flags_(flags),
+        read_backward_(read_backward) {}
+  void Accept(NodeVisitor* visitor) override;
+  int start_register() { return start_reg_; }
+  int end_register() { return end_reg_; }
+  bool read_backward() { return read_backward_; }
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override {
+    return;
+  }
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+
+ private:
+  int start_reg_;
+  int end_reg_;
+  JSRegExp::Flags flags_;
+  bool read_backward_;
+};
+
+class EndNode : public RegExpNode {
+ public:
+  enum Action { ACCEPT, BACKTRACK, NEGATIVE_SUBMATCH_SUCCESS };
+  EndNode(Action action, Zone* zone) : RegExpNode(zone), action_(action) {}
+  void Accept(NodeVisitor* visitor) override;
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override {
+    // Returning 0 from EatsAtLeast should ensure we never get here.
+    UNREACHABLE();
+  }
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override {
+    // Returning 0 from EatsAtLeast should ensure we never get here.
+    UNREACHABLE();
+  }
+
+ private:
+  Action action_;
+};
+
+class NegativeSubmatchSuccess : public EndNode {
+ public:
+  NegativeSubmatchSuccess(int stack_pointer_reg, int position_reg,
+                          int clear_capture_count, int clear_capture_start,
+                          Zone* zone)
+      : EndNode(NEGATIVE_SUBMATCH_SUCCESS, zone),
+        stack_pointer_register_(stack_pointer_reg),
+        current_position_register_(position_reg),
+        clear_capture_count_(clear_capture_count),
+        clear_capture_start_(clear_capture_start) {}
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+
+ private:
+  int stack_pointer_register_;
+  int current_position_register_;
+  int clear_capture_count_;
+  int clear_capture_start_;
+};
+
+class Guard : public ZoneObject {
+ public:
+  enum Relation { LT, GEQ };
+  Guard(int reg, Relation op, int value) : reg_(reg), op_(op), value_(value) {}
+  int reg() { return reg_; }
+  Relation op() { return op_; }
+  int value() { return value_; }
+
+ private:
+  int reg_;
+  Relation op_;
+  int value_;
+};
+
+class GuardedAlternative {
+ public:
+  explicit GuardedAlternative(RegExpNode* node)
+      : node_(node), guards_(nullptr) {}
+  void AddGuard(Guard* guard, Zone* zone);
+  RegExpNode* node() { return node_; }
+  void set_node(RegExpNode* node) { node_ = node; }
+  ZoneList<Guard*>* guards() { return guards_; }
+
+ private:
+  RegExpNode* node_;
+  ZoneList<Guard*>* guards_;
+};
+
+class AlternativeGeneration;
+
+class ChoiceNode : public RegExpNode {
+ public:
+  explicit ChoiceNode(int expected_size, Zone* zone)
+      : RegExpNode(zone),
+        alternatives_(new (zone)
+                          ZoneList<GuardedAlternative>(expected_size, zone)),
+        not_at_start_(false),
+        being_calculated_(false) {}
+  void Accept(NodeVisitor* visitor) override;
+  void AddAlternative(GuardedAlternative node) {
+    alternatives()->Add(node, zone());
+  }
+  ZoneList<GuardedAlternative>* alternatives() { return alternatives_; }
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+
+  bool being_calculated() { return being_calculated_; }
+  bool not_at_start() { return not_at_start_; }
+  void set_not_at_start() { not_at_start_ = true; }
+  void set_being_calculated(bool b) { being_calculated_ = b; }
+  virtual bool try_to_emit_quick_check_for_alternative(bool is_first) {
+    return true;
+  }
+  RegExpNode* FilterOneByte(int depth) override;
+  virtual bool read_backward() { return false; }
+
+ protected:
+  int GreedyLoopTextLengthForAlternative(GuardedAlternative* alternative);
+  ZoneList<GuardedAlternative>* alternatives_;
+
+ private:
+  template <typename...>
+  friend class Analysis;
+
+  void GenerateGuard(RegExpMacroAssembler* macro_assembler, Guard* guard,
+                     Trace* trace);
+  int CalculatePreloadCharacters(RegExpCompiler* compiler, int eats_at_least);
+  void EmitOutOfLineContinuation(RegExpCompiler* compiler, Trace* trace,
+                                 GuardedAlternative alternative,
+                                 AlternativeGeneration* alt_gen,
+                                 int preload_characters,
+                                 bool next_expects_preload);
+  void SetUpPreLoad(RegExpCompiler* compiler, Trace* current_trace,
+                    PreloadState* preloads);
+  void AssertGuardsMentionRegisters(Trace* trace);
+  int EmitOptimizedUnanchoredSearch(RegExpCompiler* compiler, Trace* trace);
+  Trace* EmitGreedyLoop(RegExpCompiler* compiler, Trace* trace,
+                        AlternativeGenerationList* alt_gens,
+                        PreloadState* preloads,
+                        GreedyLoopState* greedy_loop_state, int text_length);
+  void EmitChoices(RegExpCompiler* compiler,
+                   AlternativeGenerationList* alt_gens, int first_choice,
+                   Trace* trace, PreloadState* preloads);
+
+  // If true, this node is never checked at the start of the input.
+  // Allows a new trace to start with at_start() set to false.
+  bool not_at_start_;
+  bool being_calculated_;
+};
+
+class NegativeLookaroundChoiceNode : public ChoiceNode {
+ public:
+  explicit NegativeLookaroundChoiceNode(GuardedAlternative this_must_fail,
+                                        GuardedAlternative then_do_this,
+                                        Zone* zone)
+      : ChoiceNode(2, zone) {
+    AddAlternative(this_must_fail);
+    AddAlternative(then_do_this);
+  }
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override {
+    continue_node()->FillInBMInfo(isolate, offset, budget - 1, bm,
+                                  not_at_start);
+    if (offset == 0) set_bm_info(not_at_start, bm);
+  }
+  static constexpr int kLookaroundIndex = 0;
+  static constexpr int kContinueIndex = 1;
+  RegExpNode* lookaround_node() {
+    return alternatives()->at(kLookaroundIndex).node();
+  }
+  RegExpNode* continue_node() {
+    return alternatives()->at(kContinueIndex).node();
+  }
+  // For a negative lookahead we don't emit the quick check for the
+  // alternative that is expected to fail.  This is because quick check code
+  // starts by loading enough characters for the alternative that takes fewest
+  // characters, but on a negative lookahead the negative branch did not take
+  // part in that calculation (EatsAtLeast) so the assumptions don't hold.
+  bool try_to_emit_quick_check_for_alternative(bool is_first) override {
+    return !is_first;
+  }
+  void Accept(NodeVisitor* visitor) override;
+  RegExpNode* FilterOneByte(int depth) override;
+};
+
+class LoopChoiceNode : public ChoiceNode {
+ public:
+  LoopChoiceNode(bool body_can_be_zero_length, bool read_backward,
+                 int min_loop_iterations, Zone* zone)
+      : ChoiceNode(2, zone),
+        loop_node_(nullptr),
+        continue_node_(nullptr),
+        body_can_be_zero_length_(body_can_be_zero_length),
+        read_backward_(read_backward),
+        traversed_loop_initialization_node_(false),
+        min_loop_iterations_(min_loop_iterations) {}
+  void AddLoopAlternative(GuardedAlternative alt);
+  void AddContinueAlternative(GuardedAlternative alt);
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override;
+  void GetQuickCheckDetailsFromLoopEntry(QuickCheckDetails* details,
+                                         RegExpCompiler* compiler,
+                                         int characters_filled_in,
+                                         bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+  EatsAtLeastInfo EatsAtLeastFromLoopEntry() override;
+  RegExpNode* loop_node() { return loop_node_; }
+  RegExpNode* continue_node() { return continue_node_; }
+  bool body_can_be_zero_length() { return body_can_be_zero_length_; }
+  int min_loop_iterations() const { return min_loop_iterations_; }
+  bool read_backward() override { return read_backward_; }
+  void Accept(NodeVisitor* visitor) override;
+  RegExpNode* FilterOneByte(int depth) override;
+
+ private:
+  // AddAlternative is made private for loop nodes because alternatives
+  // should not be added freely, we need to keep track of which node
+  // goes back to the node itself.
+  void AddAlternative(GuardedAlternative node) {
+    ChoiceNode::AddAlternative(node);
+  }
+
+  RegExpNode* loop_node_;
+  RegExpNode* continue_node_;
+  bool body_can_be_zero_length_;
+  bool read_backward_;
+
+  // Temporary marker set only while generating quick check details. Represents
+  // whether GetQuickCheckDetails traversed the initialization node for this
+  // loop's counter. If so, we may be able to generate stricter quick checks
+  // because we know the loop node must match at least min_loop_iterations_
+  // times before the continuation node can match.
+  bool traversed_loop_initialization_node_;
+
+  // The minimum number of times the loop_node_ must match before the
+  // continue_node_ might be considered. This value can be temporarily decreased
+  // while generating quick check details, to represent the remaining iterations
+  // after the completed portion of the quick check details.
+  int min_loop_iterations_;
+
+  friend class IterationDecrementer;
+  friend class LoopInitializationMarker;
+};
+
+class NodeVisitor {
+ public:
+  virtual ~NodeVisitor() = default;
+#define DECLARE_VISIT(Type) virtual void Visit##Type(Type##Node* that) = 0;
+  FOR_EACH_NODE_TYPE(DECLARE_VISIT)
+#undef DECLARE_VISIT
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_NODES_H_
diff --git a/js/src/regexp/regexp-parser.cc b/js/src/regexp/regexp-parser.cc
new file mode 100644
index 0000000000..377b942477
--- /dev/null
+++ b/js/src/regexp/regexp-parser.cc
@@ -0,0 +1,2115 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-parser.h"
+
+#include <vector>
+
+#include "regexp/property-sequences.h"
+#include "regexp/regexp-macro-assembler.h"
+#include "regexp/regexp.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/uniset.h"
+#endif  // V8_INTL_SUPPORT
+
+namespace v8 {
+namespace internal {
+
+RegExpParser::RegExpParser(FlatStringReader* in, Handle<String>* error,
+                           JSRegExp::Flags flags, Isolate* isolate, Zone* zone)
+    : isolate_(isolate),
+      zone_(zone),
+      error_(error),
+      captures_(nullptr),
+      named_captures_(nullptr),
+      named_back_references_(nullptr),
+      in_(in),
+      current_(kEndMarker),
+      top_level_flags_(flags),
+      next_pos_(0),
+      captures_started_(0),
+      capture_count_(0),
+      has_more_(true),
+      simple_(false),
+      contains_anchor_(false),
+      is_scanned_for_captures_(false),
+      has_named_captures_(false),
+      failed_(false) {
+  Advance();
+}
+
+template <bool update_position>
+inline uc32 RegExpParser::ReadNext() {
+  int position = next_pos_;
+  uc32 c0 = in()->Get(position);
+  position++;
+  // Read the whole surrogate pair in case of unicode flag, if possible.
+  if (unicode() && position < in()->length() &&
+      unibrow::Utf16::IsLeadSurrogate(static_cast<uc16>(c0))) {
+    uc16 c1 = in()->Get(position);
+    if (unibrow::Utf16::IsTrailSurrogate(c1)) {
+      c0 = unibrow::Utf16::CombineSurrogatePair(static_cast<uc16>(c0), c1);
+      position++;
+    }
+  }
+  if (update_position) next_pos_ = position;
+  return c0;
+}
+
+
+uc32 RegExpParser::Next() {
+  if (has_next()) {
+    return ReadNext<false>();
+  } else {
+    return kEndMarker;
+  }
+}
+
+void RegExpParser::Advance() {
+  if (has_next()) {
+    StackLimitCheck check(isolate());
+    if (check.HasOverflowed()) {
+      if (FLAG_correctness_fuzzer_suppressions) {
+        FATAL("Aborting on stack overflow");
+      }
+      ReportError(CStrVector(
+          MessageFormatter::TemplateString(MessageTemplate::kStackOverflow)));
+    } else if (zone()->excess_allocation()) {
+      if (FLAG_correctness_fuzzer_suppressions) {
+        FATAL("Aborting on excess zone allocation");
+      }
+      ReportError(CStrVector("Regular expression too large"));
+    } else {
+      current_ = ReadNext<true>();
+    }
+  } else {
+    current_ = kEndMarker;
+    // Advance so that position() points to 1-after-the-last-character. This is
+    // important so that Reset() to this position works correctly.
+    next_pos_ = in()->length() + 1;
+    has_more_ = false;
+  }
+}
+
+
+void RegExpParser::Reset(int pos) {
+  next_pos_ = pos;
+  has_more_ = (pos < in()->length());
+  Advance();
+}
+
+void RegExpParser::Advance(int dist) {
+  next_pos_ += dist - 1;
+  Advance();
+}
+
+
+bool RegExpParser::simple() { return simple_; }
+
+bool RegExpParser::IsSyntaxCharacterOrSlash(uc32 c) {
+  switch (c) {
+    case '^':
+    case '$':
+    case '\\':
+    case '.':
+    case '*':
+    case '+':
+    case '?':
+    case '(':
+    case ')':
+    case '[':
+    case ']':
+    case '{':
+    case '}':
+    case '|':
+    case '/':
+      return true;
+    default:
+      break;
+  }
+  return false;
+}
+
+
+RegExpTree* RegExpParser::ReportError(Vector<const char> message) {
+  if (failed_) return nullptr;  // Do not overwrite any existing error.
+  failed_ = true;
+  *error_ = isolate()
+                ->factory()
+                ->NewStringFromOneByte(Vector<const uint8_t>::cast(message))
+                .ToHandleChecked();
+  // Zip to the end to make sure the no more input is read.
+  current_ = kEndMarker;
+  next_pos_ = in()->length();
+  return nullptr;
+}
+
+#define CHECK_FAILED /**/);    \
+  if (failed_) return nullptr; \
+  ((void)0
+
+// Pattern ::
+//   Disjunction
+RegExpTree* RegExpParser::ParsePattern() {
+  RegExpTree* result = ParseDisjunction(CHECK_FAILED);
+  PatchNamedBackReferences(CHECK_FAILED);
+  DCHECK(!has_more());
+  // If the result of parsing is a literal string atom, and it has the
+  // same length as the input, then the atom is identical to the input.
+  if (result->IsAtom() && result->AsAtom()->length() == in()->length()) {
+    simple_ = true;
+  }
+  return result;
+}
+
+
+// Disjunction ::
+//   Alternative
+//   Alternative | Disjunction
+// Alternative ::
+//   [empty]
+//   Term Alternative
+// Term ::
+//   Assertion
+//   Atom
+//   Atom Quantifier
+RegExpTree* RegExpParser::ParseDisjunction() {
+  // Used to store current state while parsing subexpressions.
+  RegExpParserState initial_state(nullptr, INITIAL, RegExpLookaround::LOOKAHEAD,
+                                  0, nullptr, top_level_flags_, zone());
+  RegExpParserState* state = &initial_state;
+  // Cache the builder in a local variable for quick access.
+  RegExpBuilder* builder = initial_state.builder();
+  while (true) {
+    switch (current()) {
+      case kEndMarker:
+        if (state->IsSubexpression()) {
+          // Inside a parenthesized group when hitting end of input.
+          return ReportError(CStrVector("Unterminated group"));
+        }
+        DCHECK_EQ(INITIAL, state->group_type());
+        // Parsing completed successfully.
+        return builder->ToRegExp();
+      case ')': {
+        if (!state->IsSubexpression()) {
+          return ReportError(CStrVector("Unmatched ')'"));
+        }
+        DCHECK_NE(INITIAL, state->group_type());
+
+        Advance();
+        // End disjunction parsing and convert builder content to new single
+        // regexp atom.
+        RegExpTree* body = builder->ToRegExp();
+
+        int end_capture_index = captures_started();
+
+        int capture_index = state->capture_index();
+        SubexpressionType group_type = state->group_type();
+
+        // Build result of subexpression.
+        if (group_type == CAPTURE) {
+          if (state->IsNamedCapture()) {
+            CreateNamedCaptureAtIndex(state->capture_name(),
+                                      capture_index CHECK_FAILED);
+          }
+          RegExpCapture* capture = GetCapture(capture_index);
+          capture->set_body(body);
+          body = capture;
+        } else if (group_type == GROUPING) {
+          body = new (zone()) RegExpGroup(body);
+        } else {
+          DCHECK(group_type == POSITIVE_LOOKAROUND ||
+                 group_type == NEGATIVE_LOOKAROUND);
+          bool is_positive = (group_type == POSITIVE_LOOKAROUND);
+          body = new (zone()) RegExpLookaround(
+              body, is_positive, end_capture_index - capture_index,
+              capture_index, state->lookaround_type());
+        }
+
+        // Restore previous state.
+        state = state->previous_state();
+        builder = state->builder();
+
+        builder->AddAtom(body);
+        // For compatibility with JSC and ES3, we allow quantifiers after
+        // lookaheads, and break in all cases.
+        break;
+      }
+      case '|': {
+        Advance();
+        builder->NewAlternative();
+        continue;
+      }
+      case '*':
+      case '+':
+      case '?':
+        return ReportError(CStrVector("Nothing to repeat"));
+      case '^': {
+        Advance();
+        if (builder->multiline()) {
+          builder->AddAssertion(new (zone()) RegExpAssertion(
+              RegExpAssertion::START_OF_LINE, builder->flags()));
+        } else {
+          builder->AddAssertion(new (zone()) RegExpAssertion(
+              RegExpAssertion::START_OF_INPUT, builder->flags()));
+          set_contains_anchor();
+        }
+        continue;
+      }
+      case '$': {
+        Advance();
+        RegExpAssertion::AssertionType assertion_type =
+            builder->multiline() ? RegExpAssertion::END_OF_LINE
+                                 : RegExpAssertion::END_OF_INPUT;
+        builder->AddAssertion(
+            new (zone()) RegExpAssertion(assertion_type, builder->flags()));
+        continue;
+      }
+      case '.': {
+        Advance();
+        ZoneList<CharacterRange>* ranges =
+            new (zone()) ZoneList<CharacterRange>(2, zone());
+
+        if (builder->dotall()) {
+          // Everything.
+          CharacterRange::AddClassEscape('*', ranges, false, zone());
+        } else {
+          // Everything except \x0A, \x0D, \u2028 and \u2029
+          CharacterRange::AddClassEscape('.', ranges, false, zone());
+        }
+
+        RegExpCharacterClass* cc =
+            new (zone()) RegExpCharacterClass(zone(), ranges, builder->flags());
+        builder->AddCharacterClass(cc);
+        break;
+      }
+      case '(': {
+        state = ParseOpenParenthesis(state CHECK_FAILED);
+        builder = state->builder();
+        continue;
+      }
+      case '[': {
+        RegExpTree* cc = ParseCharacterClass(builder CHECK_FAILED);
+        builder->AddCharacterClass(cc->AsCharacterClass());
+        break;
+      }
+      // Atom ::
+      //   \ AtomEscape
+      case '\\':
+        switch (Next()) {
+          case kEndMarker:
+            return ReportError(CStrVector("\\ at end of pattern"));
+          case 'b':
+            Advance(2);
+            builder->AddAssertion(new (zone()) RegExpAssertion(
+                RegExpAssertion::BOUNDARY, builder->flags()));
+            continue;
+          case 'B':
+            Advance(2);
+            builder->AddAssertion(new (zone()) RegExpAssertion(
+                RegExpAssertion::NON_BOUNDARY, builder->flags()));
+            continue;
+          // AtomEscape ::
+          //   CharacterClassEscape
+          //
+          // CharacterClassEscape :: one of
+          //   d D s S w W
+          case 'd':
+          case 'D':
+          case 's':
+          case 'S':
+          case 'w':
+          case 'W': {
+            uc32 c = Next();
+            Advance(2);
+            ZoneList<CharacterRange>* ranges =
+                new (zone()) ZoneList<CharacterRange>(2, zone());
+            CharacterRange::AddClassEscape(
+                c, ranges, unicode() && builder->ignore_case(), zone());
+            RegExpCharacterClass* cc = new (zone())
+                RegExpCharacterClass(zone(), ranges, builder->flags());
+            builder->AddCharacterClass(cc);
+            break;
+          }
+          case 'p':
+          case 'P': {
+            uc32 p = Next();
+            Advance(2);
+            if (unicode()) {
+              ZoneList<CharacterRange>* ranges =
+                  new (zone()) ZoneList<CharacterRange>(2, zone());
+              std::vector<char> name_1, name_2;
+              if (ParsePropertyClassName(&name_1, &name_2)) {
+                if (AddPropertyClassRange(ranges, p == 'P', name_1, name_2)) {
+                  RegExpCharacterClass* cc = new (zone())
+                      RegExpCharacterClass(zone(), ranges, builder->flags());
+                  builder->AddCharacterClass(cc);
+                  break;
+                }
+                if (p == 'p' && name_2.empty()) {
+                  RegExpTree* sequence = GetPropertySequence(name_1);
+                  if (sequence != nullptr) {
+                    builder->AddAtom(sequence);
+                    break;
+                  }
+                }
+              }
+              return ReportError(CStrVector("Invalid property name"));
+            } else {
+              builder->AddCharacter(p);
+            }
+            break;
+          }
+          case '1':
+          case '2':
+          case '3':
+          case '4':
+          case '5':
+          case '6':
+          case '7':
+          case '8':
+          case '9': {
+            int index = 0;
+            bool is_backref = ParseBackReferenceIndex(&index CHECK_FAILED);
+            if (is_backref) {
+              if (state->IsInsideCaptureGroup(index)) {
+                // The back reference is inside the capture group it refers to.
+                // Nothing can possibly have been captured yet, so we use empty
+                // instead. This ensures that, when checking a back reference,
+                // the capture registers of the referenced capture are either
+                // both set or both cleared.
+                builder->AddEmpty();
+              } else {
+                RegExpCapture* capture = GetCapture(index);
+                RegExpTree* atom =
+                    new (zone()) RegExpBackReference(capture, builder->flags());
+                builder->AddAtom(atom);
+              }
+              break;
+            }
+            // With /u, no identity escapes except for syntax characters
+            // are allowed. Otherwise, all identity escapes are allowed.
+            if (unicode()) {
+              return ReportError(CStrVector("Invalid escape"));
+            }
+            uc32 first_digit = Next();
+            if (first_digit == '8' || first_digit == '9') {
+              builder->AddCharacter(first_digit);
+              Advance(2);
+              break;
+            }
+            V8_FALLTHROUGH;
+          }
+          case '0': {
+            Advance();
+            if (unicode() && Next() >= '0' && Next() <= '9') {
+              // With /u, decimal escape with leading 0 are not parsed as octal.
+              return ReportError(CStrVector("Invalid decimal escape"));
+            }
+            uc32 octal = ParseOctalLiteral();
+            builder->AddCharacter(octal);
+            break;
+          }
+          // ControlEscape :: one of
+          //   f n r t v
+          case 'f':
+            Advance(2);
+            builder->AddCharacter('\f');
+            break;
+          case 'n':
+            Advance(2);
+            builder->AddCharacter('\n');
+            break;
+          case 'r':
+            Advance(2);
+            builder->AddCharacter('\r');
+            break;
+          case 't':
+            Advance(2);
+            builder->AddCharacter('\t');
+            break;
+          case 'v':
+            Advance(2);
+            builder->AddCharacter('\v');
+            break;
+          case 'c': {
+            Advance();
+            uc32 controlLetter = Next();
+            // Special case if it is an ASCII letter.
+            // Convert lower case letters to uppercase.
+            uc32 letter = controlLetter & ~('a' ^ 'A');
+            if (letter < 'A' || 'Z' < letter) {
+              // controlLetter is not in range 'A'-'Z' or 'a'-'z'.
+              // Read the backslash as a literal character instead of as
+              // starting an escape.
+              // ES#prod-annexB-ExtendedPatternCharacter
+              if (unicode()) {
+                // With /u, invalid escapes are not treated as identity escapes.
+                return ReportError(CStrVector("Invalid unicode escape"));
+              }
+              builder->AddCharacter('\\');
+            } else {
+              Advance(2);
+              builder->AddCharacter(controlLetter & 0x1F);
+            }
+            break;
+          }
+          case 'x': {
+            Advance(2);
+            uc32 value;
+            if (ParseHexEscape(2, &value)) {
+              builder->AddCharacter(value);
+            } else if (!unicode()) {
+              builder->AddCharacter('x');
+            } else {
+              // With /u, invalid escapes are not treated as identity escapes.
+              return ReportError(CStrVector("Invalid escape"));
+            }
+            break;
+          }
+          case 'u': {
+            Advance(2);
+            uc32 value;
+            if (ParseUnicodeEscape(&value)) {
+              builder->AddEscapedUnicodeCharacter(value);
+            } else if (!unicode()) {
+              builder->AddCharacter('u');
+            } else {
+              // With /u, invalid escapes are not treated as identity escapes.
+              return ReportError(CStrVector("Invalid Unicode escape"));
+            }
+            break;
+          }
+          case 'k':
+            // Either an identity escape or a named back-reference.  The two
+            // interpretations are mutually exclusive: '\k' is interpreted as
+            // an identity escape for non-Unicode patterns without named
+            // capture groups, and as the beginning of a named back-reference
+            // in all other cases.
+            if (unicode() || HasNamedCaptures()) {
+              Advance(2);
+              ParseNamedBackReference(builder, state CHECK_FAILED);
+              break;
+            }
+            V8_FALLTHROUGH;
+          default:
+            Advance();
+            // With /u, no identity escapes except for syntax characters
+            // are allowed. Otherwise, all identity escapes are allowed.
+            if (!unicode() || IsSyntaxCharacterOrSlash(current())) {
+              builder->AddCharacter(current());
+              Advance();
+            } else {
+              return ReportError(CStrVector("Invalid escape"));
+            }
+            break;
+        }
+        break;
+      case '{': {
+        int dummy;
+        bool parsed = ParseIntervalQuantifier(&dummy, &dummy CHECK_FAILED);
+        if (parsed) return ReportError(CStrVector("Nothing to repeat"));
+        V8_FALLTHROUGH;
+      }
+      case '}':
+      case ']':
+        if (unicode()) {
+          return ReportError(CStrVector("Lone quantifier brackets"));
+        }
+        V8_FALLTHROUGH;
+      default:
+        builder->AddUnicodeCharacter(current());
+        Advance();
+        break;
+    }  // end switch(current())
+
+    int min;
+    int max;
+    switch (current()) {
+      // QuantifierPrefix ::
+      //   *
+      //   +
+      //   ?
+      //   {
+      case '*':
+        min = 0;
+        max = RegExpTree::kInfinity;
+        Advance();
+        break;
+      case '+':
+        min = 1;
+        max = RegExpTree::kInfinity;
+        Advance();
+        break;
+      case '?':
+        min = 0;
+        max = 1;
+        Advance();
+        break;
+      case '{':
+        if (ParseIntervalQuantifier(&min, &max)) {
+          if (max < min) {
+            return ReportError(
+                CStrVector("numbers out of order in {} quantifier"));
+          }
+          break;
+        } else if (unicode()) {
+          // With /u, incomplete quantifiers are not allowed.
+          return ReportError(CStrVector("Incomplete quantifier"));
+        }
+        continue;
+      default:
+        continue;
+    }
+    RegExpQuantifier::QuantifierType quantifier_type = RegExpQuantifier::GREEDY;
+    if (current() == '?') {
+      quantifier_type = RegExpQuantifier::NON_GREEDY;
+      Advance();
+    } else if (FLAG_regexp_possessive_quantifier && current() == '+') {
+      // FLAG_regexp_possessive_quantifier is a debug-only flag.
+      quantifier_type = RegExpQuantifier::POSSESSIVE;
+      Advance();
+    }
+    if (!builder->AddQuantifierToAtom(min, max, quantifier_type)) {
+      return ReportError(CStrVector("Invalid quantifier"));
+    }
+  }
+}
+
+RegExpParser::RegExpParserState* RegExpParser::ParseOpenParenthesis(
+    RegExpParserState* state) {
+  RegExpLookaround::Type lookaround_type = state->lookaround_type();
+  bool is_named_capture = false;
+  JSRegExp::Flags switch_on = JSRegExp::kNone;
+  JSRegExp::Flags switch_off = JSRegExp::kNone;
+  const ZoneVector<uc16>* capture_name = nullptr;
+  SubexpressionType subexpr_type = CAPTURE;
+  Advance();
+  if (current() == '?') {
+    switch (Next()) {
+      case ':':
+        Advance(2);
+        subexpr_type = GROUPING;
+        break;
+      case '=':
+        Advance(2);
+        lookaround_type = RegExpLookaround::LOOKAHEAD;
+        subexpr_type = POSITIVE_LOOKAROUND;
+        break;
+      case '!':
+        Advance(2);
+        lookaround_type = RegExpLookaround::LOOKAHEAD;
+        subexpr_type = NEGATIVE_LOOKAROUND;
+        break;
+      case '-':
+      case 'i':
+      case 's':
+      case 'm': {
+        if (!FLAG_regexp_mode_modifiers) {
+          ReportError(CStrVector("Invalid group"));
+          return nullptr;
+        }
+        Advance();
+        bool flags_sense = true;  // Switching on flags.
+        while (subexpr_type != GROUPING) {
+          switch (current()) {
+            case '-':
+              if (!flags_sense) {
+                ReportError(CStrVector("Multiple dashes in flag group"));
+                return nullptr;
+              }
+              flags_sense = false;
+              Advance();
+              continue;
+            case 's':
+            case 'i':
+            case 'm': {
+              JSRegExp::Flags bit = JSRegExp::kUnicode;
+              if (current() == 'i') bit = JSRegExp::kIgnoreCase;
+              if (current() == 'm') bit = JSRegExp::kMultiline;
+              if (current() == 's') bit = JSRegExp::kDotAll;
+              if (((switch_on | switch_off) & bit) != 0) {
+                ReportError(CStrVector("Repeated flag in flag group"));
+                return nullptr;
+              }
+              if (flags_sense) {
+                switch_on |= bit;
+              } else {
+                switch_off |= bit;
+              }
+              Advance();
+              continue;
+            }
+            case ')': {
+              Advance();
+              state->builder()
+                  ->FlushText();  // Flush pending text using old flags.
+              // These (?i)-style flag switches don't put us in a subexpression
+              // at all, they just modify the flags in the rest of the current
+              // subexpression.
+              JSRegExp::Flags flags =
+                  (state->builder()->flags() | switch_on) & ~switch_off;
+              state->builder()->set_flags(flags);
+              return state;
+            }
+            case ':':
+              Advance();
+              subexpr_type = GROUPING;  // Will break us out of the outer loop.
+              continue;
+            default:
+              ReportError(CStrVector("Invalid flag group"));
+              return nullptr;
+          }
+        }
+        break;
+      }
+      case '<':
+        Advance();
+        if (Next() == '=') {
+          Advance(2);
+          lookaround_type = RegExpLookaround::LOOKBEHIND;
+          subexpr_type = POSITIVE_LOOKAROUND;
+          break;
+        } else if (Next() == '!') {
+          Advance(2);
+          lookaround_type = RegExpLookaround::LOOKBEHIND;
+          subexpr_type = NEGATIVE_LOOKAROUND;
+          break;
+        }
+        is_named_capture = true;
+        has_named_captures_ = true;
+        Advance();
+        break;
+      default:
+        ReportError(CStrVector("Invalid group"));
+        return nullptr;
+    }
+  }
+  if (subexpr_type == CAPTURE) {
+    if (captures_started_ >= JSRegExp::kMaxCaptures) {
+      ReportError(CStrVector("Too many captures"));
+      return nullptr;
+    }
+    captures_started_++;
+
+    if (is_named_capture) {
+      capture_name = ParseCaptureGroupName(CHECK_FAILED);
+    }
+  }
+  JSRegExp::Flags flags = (state->builder()->flags() | switch_on) & ~switch_off;
+  // Store current state and begin new disjunction parsing.
+  return new (zone())
+      RegExpParserState(state, subexpr_type, lookaround_type, captures_started_,
+                        capture_name, flags, zone());
+}
+
+#ifdef DEBUG
+// Currently only used in an DCHECK.
+static bool IsSpecialClassEscape(uc32 c) {
+  switch (c) {
+    case 'd':
+    case 'D':
+    case 's':
+    case 'S':
+    case 'w':
+    case 'W':
+      return true;
+    default:
+      return false;
+  }
+}
+#endif
+
+
+// In order to know whether an escape is a backreference or not we have to scan
+// the entire regexp and find the number of capturing parentheses.  However we
+// don't want to scan the regexp twice unless it is necessary.  This mini-parser
+// is called when needed.  It can see the difference between capturing and
+// noncapturing parentheses and can skip character classes and backslash-escaped
+// characters.
+void RegExpParser::ScanForCaptures() {
+  DCHECK(!is_scanned_for_captures_);
+  const int saved_position = position();
+  // Start with captures started previous to current position
+  int capture_count = captures_started();
+  // Add count of captures after this position.
+  int n;
+  while ((n = current()) != kEndMarker) {
+    Advance();
+    switch (n) {
+      case '\\':
+        Advance();
+        break;
+      case '[': {
+        int c;
+        while ((c = current()) != kEndMarker) {
+          Advance();
+          if (c == '\\') {
+            Advance();
+          } else {
+            if (c == ']') break;
+          }
+        }
+        break;
+      }
+      case '(':
+        if (current() == '?') {
+          // At this point we could be in
+          // * a non-capturing group '(:',
+          // * a lookbehind assertion '(?<=' '(?<!'
+          // * or a named capture '(?<'.
+          //
+          // Of these, only named captures are capturing groups.
+
+          Advance();
+          if (current() != '<') break;
+
+          Advance();
+          if (current() == '=' || current() == '!') break;
+
+          // Found a possible named capture. It could turn out to be a syntax
+          // error (e.g. an unterminated or invalid name), but that distinction
+          // does not matter for our purposes.
+          has_named_captures_ = true;
+        }
+        capture_count++;
+        break;
+    }
+  }
+  capture_count_ = capture_count;
+  is_scanned_for_captures_ = true;
+  Reset(saved_position);
+}
+
+
+bool RegExpParser::ParseBackReferenceIndex(int* index_out) {
+  DCHECK_EQ('\\', current());
+  DCHECK('1' <= Next() && Next() <= '9');
+  // Try to parse a decimal literal that is no greater than the total number
+  // of left capturing parentheses in the input.
+  int start = position();
+  int value = Next() - '0';
+  Advance(2);
+  while (true) {
+    uc32 c = current();
+    if (IsDecimalDigit(c)) {
+      value = 10 * value + (c - '0');
+      if (value > JSRegExp::kMaxCaptures) {
+        Reset(start);
+        return false;
+      }
+      Advance();
+    } else {
+      break;
+    }
+  }
+  if (value > captures_started()) {
+    if (!is_scanned_for_captures_) ScanForCaptures();
+    if (value > capture_count_) {
+      Reset(start);
+      return false;
+    }
+  }
+  *index_out = value;
+  return true;
+}
+
+static void push_code_unit(ZoneVector<uc16>* v, uint32_t code_unit) {
+  if (code_unit <= unibrow::Utf16::kMaxNonSurrogateCharCode) {
+    v->push_back(code_unit);
+  } else {
+    v->push_back(unibrow::Utf16::LeadSurrogate(code_unit));
+    v->push_back(unibrow::Utf16::TrailSurrogate(code_unit));
+  }
+}
+
+const ZoneVector<uc16>* RegExpParser::ParseCaptureGroupName() {
+  ZoneVector<uc16>* name =
+      new (zone()->New(sizeof(ZoneVector<uc16>))) ZoneVector<uc16>(zone());
+
+  bool at_start = true;
+  while (true) {
+    uc32 c = current();
+    Advance();
+
+    // Convert unicode escapes.
+    if (c == '\\' && current() == 'u') {
+      Advance();
+      if (!ParseUnicodeEscape(&c)) {
+        ReportError(CStrVector("Invalid Unicode escape sequence"));
+        return nullptr;
+      }
+    }
+
+    // The backslash char is misclassified as both ID_Start and ID_Continue.
+    if (c == '\\') {
+      ReportError(CStrVector("Invalid capture group name"));
+      return nullptr;
+    }
+
+    if (at_start) {
+      if (!IsIdentifierStart(c)) {
+        ReportError(CStrVector("Invalid capture group name"));
+        return nullptr;
+      }
+      push_code_unit(name, c);
+      at_start = false;
+    } else {
+      if (c == '>') {
+        break;
+      } else if (IsIdentifierPart(c)) {
+        push_code_unit(name, c);
+      } else {
+        ReportError(CStrVector("Invalid capture group name"));
+        return nullptr;
+      }
+    }
+  }
+
+  return name;
+}
+
+bool RegExpParser::CreateNamedCaptureAtIndex(const ZoneVector<uc16>* name,
+                                             int index) {
+  DCHECK(0 < index && index <= captures_started_);
+  DCHECK_NOT_NULL(name);
+
+  RegExpCapture* capture = GetCapture(index);
+  DCHECK_NULL(capture->name());
+
+  capture->set_name(name);
+
+  if (named_captures_ == nullptr) {
+    named_captures_ = new (zone_->New(sizeof(*named_captures_)))
+        ZoneSet<RegExpCapture*, RegExpCaptureNameLess>(zone());
+  } else {
+    // Check for duplicates and bail if we find any.
+
+    const auto& named_capture_it = named_captures_->find(capture);
+    if (named_capture_it != named_captures_->end()) {
+      ReportError(CStrVector("Duplicate capture group name"));
+      return false;
+    }
+  }
+
+  named_captures_->emplace(capture);
+
+  return true;
+}
+
+bool RegExpParser::ParseNamedBackReference(RegExpBuilder* builder,
+                                           RegExpParserState* state) {
+  // The parser is assumed to be on the '<' in \k<name>.
+  if (current() != '<') {
+    ReportError(CStrVector("Invalid named reference"));
+    return false;
+  }
+
+  Advance();
+  const ZoneVector<uc16>* name = ParseCaptureGroupName();
+  if (name == nullptr) {
+    return false;
+  }
+
+  if (state->IsInsideCaptureGroup(name)) {
+    builder->AddEmpty();
+  } else {
+    RegExpBackReference* atom =
+        new (zone()) RegExpBackReference(builder->flags());
+    atom->set_name(name);
+
+    builder->AddAtom(atom);
+
+    if (named_back_references_ == nullptr) {
+      named_back_references_ =
+          new (zone()) ZoneList<RegExpBackReference*>(1, zone());
+    }
+    named_back_references_->Add(atom, zone());
+  }
+
+  return true;
+}
+
+void RegExpParser::PatchNamedBackReferences() {
+  if (named_back_references_ == nullptr) return;
+
+  if (named_captures_ == nullptr) {
+    ReportError(CStrVector("Invalid named capture referenced"));
+    return;
+  }
+
+  // Look up and patch the actual capture for each named back reference.
+
+  for (int i = 0; i < named_back_references_->length(); i++) {
+    RegExpBackReference* ref = named_back_references_->at(i);
+
+    // Capture used to search the named_captures_ by name, index of the
+    // capture is never used.
+    static const int kInvalidIndex = 0;
+    RegExpCapture* search_capture = new (zone()) RegExpCapture(kInvalidIndex);
+    DCHECK_NULL(search_capture->name());
+    search_capture->set_name(ref->name());
+
+    int index = -1;
+    const auto& capture_it = named_captures_->find(search_capture);
+    if (capture_it != named_captures_->end()) {
+      index = (*capture_it)->index();
+    } else {
+      ReportError(CStrVector("Invalid named capture referenced"));
+      return;
+    }
+
+    ref->set_capture(GetCapture(index));
+  }
+}
+
+RegExpCapture* RegExpParser::GetCapture(int index) {
+  // The index for the capture groups are one-based. Its index in the list is
+  // zero-based.
+  int know_captures =
+      is_scanned_for_captures_ ? capture_count_ : captures_started_;
+  DCHECK(index <= know_captures);
+  if (captures_ == nullptr) {
+    captures_ = new (zone()) ZoneList<RegExpCapture*>(know_captures, zone());
+  }
+  while (captures_->length() < know_captures) {
+    captures_->Add(new (zone()) RegExpCapture(captures_->length() + 1), zone());
+  }
+  return captures_->at(index - 1);
+}
+
+namespace {
+
+struct RegExpCaptureIndexLess {
+  bool operator()(const RegExpCapture* lhs, const RegExpCapture* rhs) const {
+    DCHECK_NOT_NULL(lhs);
+    DCHECK_NOT_NULL(rhs);
+    return lhs->index() < rhs->index();
+  }
+};
+
+}  // namespace
+
+Handle<FixedArray> RegExpParser::CreateCaptureNameMap() {
+  if (named_captures_ == nullptr || named_captures_->empty()) {
+    return Handle<FixedArray>();
+  }
+
+  // Named captures are sorted by name (because the set is used to ensure
+  // name uniqueness). But the capture name map must to be sorted by index.
+
+  ZoneVector<RegExpCapture*> sorted_named_captures(
+      named_captures_->begin(), named_captures_->end(), zone());
+  std::sort(sorted_named_captures.begin(), sorted_named_captures.end(),
+            RegExpCaptureIndexLess{});
+  DCHECK_EQ(sorted_named_captures.size(), named_captures_->size());
+
+  Factory* factory = isolate()->factory();
+
+  int len = static_cast<int>(sorted_named_captures.size()) * 2;
+  Handle<FixedArray> array = factory->NewFixedArray(len);
+
+  int i = 0;
+  for (const auto& capture : sorted_named_captures) {
+    Vector<const uc16> capture_name(capture->name()->data(),
+                                    capture->name()->size());
+    // CSA code in ConstructNewResultFromMatchInfo requires these strings to be
+    // internalized so they can be used as property names in the 'exec' results.
+    Handle<String> name = factory->InternalizeString(capture_name);
+    array->set(i * 2, *name);
+    array->set(i * 2 + 1, Smi::FromInt(capture->index()));
+
+    i++;
+  }
+  DCHECK_EQ(i * 2, len);
+
+  return array;
+}
+
+bool RegExpParser::HasNamedCaptures() {
+  if (has_named_captures_ || is_scanned_for_captures_) {
+    return has_named_captures_;
+  }
+
+  ScanForCaptures();
+  DCHECK(is_scanned_for_captures_);
+  return has_named_captures_;
+}
+
+bool RegExpParser::RegExpParserState::IsInsideCaptureGroup(int index) {
+  for (RegExpParserState* s = this; s != nullptr; s = s->previous_state()) {
+    if (s->group_type() != CAPTURE) continue;
+    // Return true if we found the matching capture index.
+    if (index == s->capture_index()) return true;
+    // Abort if index is larger than what has been parsed up till this state.
+    if (index > s->capture_index()) return false;
+  }
+  return false;
+}
+
+bool RegExpParser::RegExpParserState::IsInsideCaptureGroup(
+    const ZoneVector<uc16>* name) {
+  DCHECK_NOT_NULL(name);
+  for (RegExpParserState* s = this; s != nullptr; s = s->previous_state()) {
+    if (s->capture_name() == nullptr) continue;
+    if (*s->capture_name() == *name) return true;
+  }
+  return false;
+}
+
+// QuantifierPrefix ::
+//   { DecimalDigits }
+//   { DecimalDigits , }
+//   { DecimalDigits , DecimalDigits }
+//
+// Returns true if parsing succeeds, and set the min_out and max_out
+// values. Values are truncated to RegExpTree::kInfinity if they overflow.
+bool RegExpParser::ParseIntervalQuantifier(int* min_out, int* max_out) {
+  DCHECK_EQ(current(), '{');
+  int start = position();
+  Advance();
+  int min = 0;
+  if (!IsDecimalDigit(current())) {
+    Reset(start);
+    return false;
+  }
+  while (IsDecimalDigit(current())) {
+    int next = current() - '0';
+    if (min > (RegExpTree::kInfinity - next) / 10) {
+      // Overflow. Skip past remaining decimal digits and return -1.
+      do {
+        Advance();
+      } while (IsDecimalDigit(current()));
+      min = RegExpTree::kInfinity;
+      break;
+    }
+    min = 10 * min + next;
+    Advance();
+  }
+  int max = 0;
+  if (current() == '}') {
+    max = min;
+    Advance();
+  } else if (current() == ',') {
+    Advance();
+    if (current() == '}') {
+      max = RegExpTree::kInfinity;
+      Advance();
+    } else {
+      while (IsDecimalDigit(current())) {
+        int next = current() - '0';
+        if (max > (RegExpTree::kInfinity - next) / 10) {
+          do {
+            Advance();
+          } while (IsDecimalDigit(current()));
+          max = RegExpTree::kInfinity;
+          break;
+        }
+        max = 10 * max + next;
+        Advance();
+      }
+      if (current() != '}') {
+        Reset(start);
+        return false;
+      }
+      Advance();
+    }
+  } else {
+    Reset(start);
+    return false;
+  }
+  *min_out = min;
+  *max_out = max;
+  return true;
+}
+
+
+uc32 RegExpParser::ParseOctalLiteral() {
+  DCHECK(('0' <= current() && current() <= '7') || current() == kEndMarker);
+  // For compatibility with some other browsers (not all), we parse
+  // up to three octal digits with a value below 256.
+  // ES#prod-annexB-LegacyOctalEscapeSequence
+  uc32 value = current() - '0';
+  Advance();
+  if ('0' <= current() && current() <= '7') {
+    value = value * 8 + current() - '0';
+    Advance();
+    if (value < 32 && '0' <= current() && current() <= '7') {
+      value = value * 8 + current() - '0';
+      Advance();
+    }
+  }
+  return value;
+}
+
+
+bool RegExpParser::ParseHexEscape(int length, uc32* value) {
+  int start = position();
+  uc32 val = 0;
+  for (int i = 0; i < length; ++i) {
+    uc32 c = current();
+    int d = HexValue(c);
+    if (d < 0) {
+      Reset(start);
+      return false;
+    }
+    val = val * 16 + d;
+    Advance();
+  }
+  *value = val;
+  return true;
+}
+
+// This parses RegExpUnicodeEscapeSequence as described in ECMA262.
+bool RegExpParser::ParseUnicodeEscape(uc32* value) {
+  // Accept both \uxxxx and \u{xxxxxx} (if harmony unicode escapes are
+  // allowed). In the latter case, the number of hex digits between { } is
+  // arbitrary. \ and u have already been read.
+  if (current() == '{' && unicode()) {
+    int start = position();
+    Advance();
+    if (ParseUnlimitedLengthHexNumber(0x10FFFF, value)) {
+      if (current() == '}') {
+        Advance();
+        return true;
+      }
+    }
+    Reset(start);
+    return false;
+  }
+  // \u but no {, or \u{...} escapes not allowed.
+  bool result = ParseHexEscape(4, value);
+  if (result && unicode() && unibrow::Utf16::IsLeadSurrogate(*value) &&
+      current() == '\\') {
+    // Attempt to read trail surrogate.
+    int start = position();
+    if (Next() == 'u') {
+      Advance(2);
+      uc32 trail;
+      if (ParseHexEscape(4, &trail) &&
+          unibrow::Utf16::IsTrailSurrogate(trail)) {
+        *value = unibrow::Utf16::CombineSurrogatePair(static_cast<uc16>(*value),
+                                                      static_cast<uc16>(trail));
+        return true;
+      }
+    }
+    Reset(start);
+  }
+  return result;
+}
+
+#ifdef V8_INTL_SUPPORT
+
+namespace {
+
+bool IsExactPropertyAlias(const char* property_name, UProperty property) {
+  const char* short_name = u_getPropertyName(property, U_SHORT_PROPERTY_NAME);
+  if (short_name != nullptr && strcmp(property_name, short_name) == 0)
+    return true;
+  for (int i = 0;; i++) {
+    const char* long_name = u_getPropertyName(
+        property, static_cast<UPropertyNameChoice>(U_LONG_PROPERTY_NAME + i));
+    if (long_name == nullptr) break;
+    if (strcmp(property_name, long_name) == 0) return true;
+  }
+  return false;
+}
+
+bool IsExactPropertyValueAlias(const char* property_value_name,
+                               UProperty property, int32_t property_value) {
+  const char* short_name =
+      u_getPropertyValueName(property, property_value, U_SHORT_PROPERTY_NAME);
+  if (short_name != nullptr && strcmp(property_value_name, short_name) == 0) {
+    return true;
+  }
+  for (int i = 0;; i++) {
+    const char* long_name = u_getPropertyValueName(
+        property, property_value,
+        static_cast<UPropertyNameChoice>(U_LONG_PROPERTY_NAME + i));
+    if (long_name == nullptr) break;
+    if (strcmp(property_value_name, long_name) == 0) return true;
+  }
+  return false;
+}
+
+bool LookupPropertyValueName(UProperty property,
+                             const char* property_value_name, bool negate,
+                             ZoneList<CharacterRange>* result, Zone* zone) {
+  UProperty property_for_lookup = property;
+  if (property_for_lookup == UCHAR_SCRIPT_EXTENSIONS) {
+    // For the property Script_Extensions, we have to do the property value
+    // name lookup as if the property is Script.
+    property_for_lookup = UCHAR_SCRIPT;
+  }
+  int32_t property_value =
+      u_getPropertyValueEnum(property_for_lookup, property_value_name);
+  if (property_value == UCHAR_INVALID_CODE) return false;
+
+  // We require the property name to match exactly to one of the property value
+  // aliases. However, u_getPropertyValueEnum uses loose matching.
+  if (!IsExactPropertyValueAlias(property_value_name, property_for_lookup,
+                                 property_value)) {
+    return false;
+  }
+
+  UErrorCode ec = U_ZERO_ERROR;
+  icu::UnicodeSet set;
+  set.applyIntPropertyValue(property, property_value, ec);
+  bool success = ec == U_ZERO_ERROR && !set.isEmpty();
+
+  if (success) {
+    set.removeAllStrings();
+    if (negate) set.complement();
+    for (int i = 0; i < set.getRangeCount(); i++) {
+      result->Add(
+          CharacterRange::Range(set.getRangeStart(i), set.getRangeEnd(i)),
+          zone);
+    }
+  }
+  return success;
+}
+
+template <size_t N>
+inline bool NameEquals(const char* name, const char (&literal)[N]) {
+  return strncmp(name, literal, N + 1) == 0;
+}
+
+bool LookupSpecialPropertyValueName(const char* name,
+                                    ZoneList<CharacterRange>* result,
+                                    bool negate, Zone* zone) {
+  if (NameEquals(name, "Any")) {
+    if (negate) {
+      // Leave the list of character ranges empty, since the negation of 'Any'
+      // is the empty set.
+    } else {
+      result->Add(CharacterRange::Everything(), zone);
+    }
+  } else if (NameEquals(name, "ASCII")) {
+    result->Add(negate ? CharacterRange::Range(0x80, String::kMaxCodePoint)
+                       : CharacterRange::Range(0x0, 0x7F),
+                zone);
+  } else if (NameEquals(name, "Assigned")) {
+    return LookupPropertyValueName(UCHAR_GENERAL_CATEGORY, "Unassigned",
+                                   !negate, result, zone);
+  } else {
+    return false;
+  }
+  return true;
+}
+
+// Explicitly whitelist supported binary properties. The spec forbids supporting
+// properties outside of this set to ensure interoperability.
+bool IsSupportedBinaryProperty(UProperty property) {
+  switch (property) {
+    case UCHAR_ALPHABETIC:
+    // 'Any' is not supported by ICU. See LookupSpecialPropertyValueName.
+    // 'ASCII' is not supported by ICU. See LookupSpecialPropertyValueName.
+    case UCHAR_ASCII_HEX_DIGIT:
+    // 'Assigned' is not supported by ICU. See LookupSpecialPropertyValueName.
+    case UCHAR_BIDI_CONTROL:
+    case UCHAR_BIDI_MIRRORED:
+    case UCHAR_CASE_IGNORABLE:
+    case UCHAR_CASED:
+    case UCHAR_CHANGES_WHEN_CASEFOLDED:
+    case UCHAR_CHANGES_WHEN_CASEMAPPED:
+    case UCHAR_CHANGES_WHEN_LOWERCASED:
+    case UCHAR_CHANGES_WHEN_NFKC_CASEFOLDED:
+    case UCHAR_CHANGES_WHEN_TITLECASED:
+    case UCHAR_CHANGES_WHEN_UPPERCASED:
+    case UCHAR_DASH:
+    case UCHAR_DEFAULT_IGNORABLE_CODE_POINT:
+    case UCHAR_DEPRECATED:
+    case UCHAR_DIACRITIC:
+    case UCHAR_EMOJI:
+    case UCHAR_EMOJI_COMPONENT:
+    case UCHAR_EMOJI_MODIFIER_BASE:
+    case UCHAR_EMOJI_MODIFIER:
+    case UCHAR_EMOJI_PRESENTATION:
+    case UCHAR_EXTENDED_PICTOGRAPHIC:
+    case UCHAR_EXTENDER:
+    case UCHAR_GRAPHEME_BASE:
+    case UCHAR_GRAPHEME_EXTEND:
+    case UCHAR_HEX_DIGIT:
+    case UCHAR_ID_CONTINUE:
+    case UCHAR_ID_START:
+    case UCHAR_IDEOGRAPHIC:
+    case UCHAR_IDS_BINARY_OPERATOR:
+    case UCHAR_IDS_TRINARY_OPERATOR:
+    case UCHAR_JOIN_CONTROL:
+    case UCHAR_LOGICAL_ORDER_EXCEPTION:
+    case UCHAR_LOWERCASE:
+    case UCHAR_MATH:
+    case UCHAR_NONCHARACTER_CODE_POINT:
+    case UCHAR_PATTERN_SYNTAX:
+    case UCHAR_PATTERN_WHITE_SPACE:
+    case UCHAR_QUOTATION_MARK:
+    case UCHAR_RADICAL:
+    case UCHAR_REGIONAL_INDICATOR:
+    case UCHAR_S_TERM:
+    case UCHAR_SOFT_DOTTED:
+    case UCHAR_TERMINAL_PUNCTUATION:
+    case UCHAR_UNIFIED_IDEOGRAPH:
+    case UCHAR_UPPERCASE:
+    case UCHAR_VARIATION_SELECTOR:
+    case UCHAR_WHITE_SPACE:
+    case UCHAR_XID_CONTINUE:
+    case UCHAR_XID_START:
+      return true;
+    default:
+      break;
+  }
+  return false;
+}
+
+bool IsUnicodePropertyValueCharacter(char c) {
+  // https://tc39.github.io/proposal-regexp-unicode-property-escapes/
+  //
+  // Note that using this to validate each parsed char is quite conservative.
+  // A possible alternative solution would be to only ensure the parsed
+  // property name/value candidate string does not contain '\0' characters and
+  // let ICU lookups trigger the final failure.
+  if ('a' <= c && c <= 'z') return true;
+  if ('A' <= c && c <= 'Z') return true;
+  if ('0' <= c && c <= '9') return true;
+  return (c == '_');
+}
+
+}  // anonymous namespace
+
+bool RegExpParser::ParsePropertyClassName(std::vector<char>* name_1,
+                                          std::vector<char>* name_2) {
+  DCHECK(name_1->empty());
+  DCHECK(name_2->empty());
+  // Parse the property class as follows:
+  // - In \p{name}, 'name' is interpreted
+  //   - either as a general category property value name.
+  //   - or as a binary property name.
+  // - In \p{name=value}, 'name' is interpreted as an enumerated property name,
+  //   and 'value' is interpreted as one of the available property value names.
+  // - Aliases in PropertyAlias.txt and PropertyValueAlias.txt can be used.
+  // - Loose matching is not applied.
+  if (current() == '{') {
+    // Parse \p{[PropertyName=]PropertyNameValue}
+    for (Advance(); current() != '}' && current() != '='; Advance()) {
+      if (!IsUnicodePropertyValueCharacter(current())) return false;
+      if (!has_next()) return false;
+      name_1->push_back(static_cast<char>(current()));
+    }
+    if (current() == '=') {
+      for (Advance(); current() != '}'; Advance()) {
+        if (!IsUnicodePropertyValueCharacter(current())) return false;
+        if (!has_next()) return false;
+        name_2->push_back(static_cast<char>(current()));
+      }
+      name_2->push_back(0);  // null-terminate string.
+    }
+  } else {
+    return false;
+  }
+  Advance();
+  name_1->push_back(0);  // null-terminate string.
+
+  DCHECK(name_1->size() - 1 == std::strlen(name_1->data()));
+  DCHECK(name_2->empty() || name_2->size() - 1 == std::strlen(name_2->data()));
+  return true;
+}
+
+bool RegExpParser::AddPropertyClassRange(ZoneList<CharacterRange>* add_to,
+                                         bool negate,
+                                         const std::vector<char>& name_1,
+                                         const std::vector<char>& name_2) {
+  if (name_2.empty()) {
+    // First attempt to interpret as general category property value name.
+    const char* name = name_1.data();
+    if (LookupPropertyValueName(UCHAR_GENERAL_CATEGORY_MASK, name, negate,
+                                add_to, zone())) {
+      return true;
+    }
+    // Interpret "Any", "ASCII", and "Assigned".
+    if (LookupSpecialPropertyValueName(name, add_to, negate, zone())) {
+      return true;
+    }
+    // Then attempt to interpret as binary property name with value name 'Y'.
+    UProperty property = u_getPropertyEnum(name);
+    if (!IsSupportedBinaryProperty(property)) return false;
+    if (!IsExactPropertyAlias(name, property)) return false;
+    return LookupPropertyValueName(property, negate ? "N" : "Y", false, add_to,
+                                   zone());
+  } else {
+    // Both property name and value name are specified. Attempt to interpret
+    // the property name as enumerated property.
+    const char* property_name = name_1.data();
+    const char* value_name = name_2.data();
+    UProperty property = u_getPropertyEnum(property_name);
+    if (!IsExactPropertyAlias(property_name, property)) return false;
+    if (property == UCHAR_GENERAL_CATEGORY) {
+      // We want to allow aggregate value names such as "Letter".
+      property = UCHAR_GENERAL_CATEGORY_MASK;
+    } else if (property != UCHAR_SCRIPT &&
+               property != UCHAR_SCRIPT_EXTENSIONS) {
+      return false;
+    }
+    return LookupPropertyValueName(property, value_name, negate, add_to,
+                                   zone());
+  }
+}
+
+RegExpTree* RegExpParser::GetPropertySequence(const std::vector<char>& name_1) {
+  if (!FLAG_harmony_regexp_sequence) return nullptr;
+  const char* name = name_1.data();
+  const uc32* sequence_list = nullptr;
+  JSRegExp::Flags flags = JSRegExp::kUnicode;
+  if (NameEquals(name, "Emoji_Flag_Sequence")) {
+    sequence_list = UnicodePropertySequences::kEmojiFlagSequences;
+  } else if (NameEquals(name, "Emoji_Tag_Sequence")) {
+    sequence_list = UnicodePropertySequences::kEmojiTagSequences;
+  } else if (NameEquals(name, "Emoji_ZWJ_Sequence")) {
+    sequence_list = UnicodePropertySequences::kEmojiZWJSequences;
+  }
+  if (sequence_list != nullptr) {
+    // TODO(yangguo): this creates huge regexp code. Alternative to this is
+    // to create a new operator that checks for these sequences at runtime.
+    RegExpBuilder builder(zone(), flags);
+    while (true) {                   // Iterate through list of sequences.
+      while (*sequence_list != 0) {  // Iterate through sequence.
+        builder.AddUnicodeCharacter(*sequence_list);
+        sequence_list++;
+      }
+      sequence_list++;
+      if (*sequence_list == 0) break;
+      builder.NewAlternative();
+    }
+    return builder.ToRegExp();
+  }
+
+  if (NameEquals(name, "Emoji_Keycap_Sequence")) {
+    // https://unicode.org/reports/tr51/#def_emoji_keycap_sequence
+    // emoji_keycap_sequence := [0-9#*] \x{FE0F 20E3}
+    RegExpBuilder builder(zone(), flags);
+    ZoneList<CharacterRange>* prefix_ranges =
+        new (zone()) ZoneList<CharacterRange>(2, zone());
+    prefix_ranges->Add(CharacterRange::Range('0', '9'), zone());
+    prefix_ranges->Add(CharacterRange::Singleton('#'), zone());
+    prefix_ranges->Add(CharacterRange::Singleton('*'), zone());
+    builder.AddCharacterClass(
+        new (zone()) RegExpCharacterClass(zone(), prefix_ranges, flags));
+    builder.AddCharacter(0xFE0F);
+    builder.AddCharacter(0x20E3);
+    return builder.ToRegExp();
+  } else if (NameEquals(name, "Emoji_Modifier_Sequence")) {
+    // https://unicode.org/reports/tr51/#def_emoji_modifier_sequence
+    // emoji_modifier_sequence := emoji_modifier_base emoji_modifier
+    RegExpBuilder builder(zone(), flags);
+    ZoneList<CharacterRange>* modifier_base_ranges =
+        new (zone()) ZoneList<CharacterRange>(2, zone());
+    LookupPropertyValueName(UCHAR_EMOJI_MODIFIER_BASE, "Y", false,
+                            modifier_base_ranges, zone());
+    builder.AddCharacterClass(
+        new (zone()) RegExpCharacterClass(zone(), modifier_base_ranges, flags));
+    ZoneList<CharacterRange>* modifier_ranges =
+        new (zone()) ZoneList<CharacterRange>(2, zone());
+    LookupPropertyValueName(UCHAR_EMOJI_MODIFIER, "Y", false, modifier_ranges,
+                            zone());
+    builder.AddCharacterClass(
+        new (zone()) RegExpCharacterClass(zone(), modifier_ranges, flags));
+    return builder.ToRegExp();
+  }
+
+  return nullptr;
+}
+
+#else  // V8_INTL_SUPPORT
+
+bool RegExpParser::ParsePropertyClassName(std::vector<char>* name_1,
+                                          std::vector<char>* name_2) {
+  return false;
+}
+
+bool RegExpParser::AddPropertyClassRange(ZoneList<CharacterRange>* add_to,
+                                         bool negate,
+                                         const std::vector<char>& name_1,
+                                         const std::vector<char>& name_2) {
+  return false;
+}
+
+RegExpTree* RegExpParser::GetPropertySequence(const std::vector<char>& name) {
+  return nullptr;
+}
+
+#endif  // V8_INTL_SUPPORT
+
+bool RegExpParser::ParseUnlimitedLengthHexNumber(int max_value, uc32* value) {
+  uc32 x = 0;
+  int d = HexValue(current());
+  if (d < 0) {
+    return false;
+  }
+  while (d >= 0) {
+    x = x * 16 + d;
+    if (x > max_value) {
+      return false;
+    }
+    Advance();
+    d = HexValue(current());
+  }
+  *value = x;
+  return true;
+}
+
+
+uc32 RegExpParser::ParseClassCharacterEscape() {
+  DCHECK_EQ('\\', current());
+  DCHECK(has_next() && !IsSpecialClassEscape(Next()));
+  Advance();
+  switch (current()) {
+    case 'b':
+      Advance();
+      return '\b';
+    // ControlEscape :: one of
+    //   f n r t v
+    case 'f':
+      Advance();
+      return '\f';
+    case 'n':
+      Advance();
+      return '\n';
+    case 'r':
+      Advance();
+      return '\r';
+    case 't':
+      Advance();
+      return '\t';
+    case 'v':
+      Advance();
+      return '\v';
+    case 'c': {
+      uc32 controlLetter = Next();
+      uc32 letter = controlLetter & ~('A' ^ 'a');
+      // Inside a character class, we also accept digits and underscore as
+      // control characters, unless with /u. See Annex B:
+      // ES#prod-annexB-ClassControlLetter
+      if (letter >= 'A' && letter <= 'Z') {
+        Advance(2);
+        // Control letters mapped to ASCII control characters in the range
+        // 0x00-0x1F.
+        return controlLetter & 0x1F;
+      }
+      if (unicode()) {
+        // With /u, invalid escapes are not treated as identity escapes.
+        ReportError(CStrVector("Invalid class escape"));
+        return 0;
+      }
+      if ((controlLetter >= '0' && controlLetter <= '9') ||
+          controlLetter == '_') {
+        Advance(2);
+        return controlLetter & 0x1F;
+      }
+      // We match JSC in reading the backslash as a literal
+      // character instead of as starting an escape.
+      // TODO(v8:6201): Not yet covered by the spec.
+      return '\\';
+    }
+    case '0':
+      // With /u, \0 is interpreted as NUL if not followed by another digit.
+      if (unicode() && !(Next() >= '0' && Next() <= '9')) {
+        Advance();
+        return 0;
+      }
+      V8_FALLTHROUGH;
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+      // For compatibility, we interpret a decimal escape that isn't
+      // a back reference (and therefore either \0 or not valid according
+      // to the specification) as a 1..3 digit octal character code.
+      // ES#prod-annexB-LegacyOctalEscapeSequence
+      if (unicode()) {
+        // With /u, decimal escape is not interpreted as octal character code.
+        ReportError(CStrVector("Invalid class escape"));
+        return 0;
+      }
+      return ParseOctalLiteral();
+    case 'x': {
+      Advance();
+      uc32 value;
+      if (ParseHexEscape(2, &value)) return value;
+      if (unicode()) {
+        // With /u, invalid escapes are not treated as identity escapes.
+        ReportError(CStrVector("Invalid escape"));
+        return 0;
+      }
+      // If \x is not followed by a two-digit hexadecimal, treat it
+      // as an identity escape.
+      return 'x';
+    }
+    case 'u': {
+      Advance();
+      uc32 value;
+      if (ParseUnicodeEscape(&value)) return value;
+      if (unicode()) {
+        // With /u, invalid escapes are not treated as identity escapes.
+        ReportError(CStrVector("Invalid unicode escape"));
+        return 0;
+      }
+      // If \u is not followed by a two-digit hexadecimal, treat it
+      // as an identity escape.
+      return 'u';
+    }
+    default: {
+      uc32 result = current();
+      // With /u, no identity escapes except for syntax characters and '-' are
+      // allowed. Otherwise, all identity escapes are allowed.
+      if (!unicode() || IsSyntaxCharacterOrSlash(result) || result == '-') {
+        Advance();
+        return result;
+      }
+      ReportError(CStrVector("Invalid escape"));
+      return 0;
+    }
+  }
+  return 0;
+}
+
+void RegExpParser::ParseClassEscape(ZoneList<CharacterRange>* ranges,
+                                    Zone* zone,
+                                    bool add_unicode_case_equivalents,
+                                    uc32* char_out, bool* is_class_escape) {
+  uc32 current_char = current();
+  if (current_char == '\\') {
+    switch (Next()) {
+      case 'w':
+      case 'W':
+      case 'd':
+      case 'D':
+      case 's':
+      case 'S': {
+        CharacterRange::AddClassEscape(static_cast<char>(Next()), ranges,
+                                       add_unicode_case_equivalents, zone);
+        Advance(2);
+        *is_class_escape = true;
+        return;
+      }
+      case kEndMarker:
+        ReportError(CStrVector("\\ at end of pattern"));
+        return;
+      case 'p':
+      case 'P':
+        if (unicode()) {
+          bool negate = Next() == 'P';
+          Advance(2);
+          std::vector<char> name_1, name_2;
+          if (!ParsePropertyClassName(&name_1, &name_2) ||
+              !AddPropertyClassRange(ranges, negate, name_1, name_2)) {
+            ReportError(CStrVector("Invalid property name in character class"));
+          }
+          *is_class_escape = true;
+          return;
+        }
+        break;
+      default:
+        break;
+    }
+    *char_out = ParseClassCharacterEscape();
+    *is_class_escape = false;
+  } else {
+    Advance();
+    *char_out = current_char;
+    *is_class_escape = false;
+  }
+}
+
+RegExpTree* RegExpParser::ParseCharacterClass(const RegExpBuilder* builder) {
+  static const char* kUnterminated = "Unterminated character class";
+  static const char* kRangeInvalid = "Invalid character class";
+  static const char* kRangeOutOfOrder = "Range out of order in character class";
+
+  DCHECK_EQ(current(), '[');
+  Advance();
+  bool is_negated = false;
+  if (current() == '^') {
+    is_negated = true;
+    Advance();
+  }
+  ZoneList<CharacterRange>* ranges =
+      new (zone()) ZoneList<CharacterRange>(2, zone());
+  bool add_unicode_case_equivalents = unicode() && builder->ignore_case();
+  while (has_more() && current() != ']') {
+    uc32 char_1, char_2;
+    bool is_class_1, is_class_2;
+    ParseClassEscape(ranges, zone(), add_unicode_case_equivalents, &char_1,
+                     &is_class_1 CHECK_FAILED);
+    if (current() == '-') {
+      Advance();
+      if (current() == kEndMarker) {
+        // If we reach the end we break out of the loop and let the
+        // following code report an error.
+        break;
+      } else if (current() == ']') {
+        if (!is_class_1) ranges->Add(CharacterRange::Singleton(char_1), zone());
+        ranges->Add(CharacterRange::Singleton('-'), zone());
+        break;
+      }
+      ParseClassEscape(ranges, zone(), add_unicode_case_equivalents, &char_2,
+                       &is_class_2 CHECK_FAILED);
+      if (is_class_1 || is_class_2) {
+        // Either end is an escaped character class. Treat the '-' verbatim.
+        if (unicode()) {
+          // ES2015 21.2.2.15.1 step 1.
+          return ReportError(CStrVector(kRangeInvalid));
+        }
+        if (!is_class_1) ranges->Add(CharacterRange::Singleton(char_1), zone());
+        ranges->Add(CharacterRange::Singleton('-'), zone());
+        if (!is_class_2) ranges->Add(CharacterRange::Singleton(char_2), zone());
+        continue;
+      }
+      // ES2015 21.2.2.15.1 step 6.
+      if (char_1 > char_2) {
+        return ReportError(CStrVector(kRangeOutOfOrder));
+      }
+      ranges->Add(CharacterRange::Range(char_1, char_2), zone());
+    } else {
+      if (!is_class_1) ranges->Add(CharacterRange::Singleton(char_1), zone());
+    }
+  }
+  if (!has_more()) {
+    return ReportError(CStrVector(kUnterminated));
+  }
+  Advance();
+  RegExpCharacterClass::CharacterClassFlags character_class_flags;
+  if (is_negated) character_class_flags = RegExpCharacterClass::NEGATED;
+  return new (zone()) RegExpCharacterClass(zone(), ranges, builder->flags(),
+                                           character_class_flags);
+}
+
+
+#undef CHECK_FAILED
+
+
+bool RegExpParser::ParseRegExp(Isolate* isolate, Zone* zone,
+                               FlatStringReader* input, JSRegExp::Flags flags,
+                               RegExpCompileData* result) {
+  DCHECK(result != nullptr);
+  RegExpParser parser(input, &result->error, flags, isolate, zone);
+  RegExpTree* tree = parser.ParsePattern();
+  if (parser.failed()) {
+    DCHECK(tree == nullptr);
+    DCHECK(!result->error.is_null());
+  } else {
+    DCHECK(tree != nullptr);
+    DCHECK(result->error.is_null());
+    if (FLAG_trace_regexp_parser) {
+      StdoutStream os;
+      tree->Print(os, zone);
+      os << "\n";
+    }
+    result->tree = tree;
+    int capture_count = parser.captures_started();
+    result->simple = tree->IsAtom() && parser.simple() && capture_count == 0;
+    result->contains_anchor = parser.contains_anchor();
+    result->capture_name_map = parser.CreateCaptureNameMap();
+    result->capture_count = capture_count;
+  }
+  return !parser.failed();
+}
+
+RegExpBuilder::RegExpBuilder(Zone* zone, JSRegExp::Flags flags)
+    : zone_(zone),
+      pending_empty_(false),
+      flags_(flags),
+      characters_(nullptr),
+      pending_surrogate_(kNoPendingSurrogate),
+      terms_(),
+      alternatives_()
+#ifdef DEBUG
+      ,
+      last_added_(ADD_NONE)
+#endif
+{
+}
+
+
+void RegExpBuilder::AddLeadSurrogate(uc16 lead_surrogate) {
+  DCHECK(unibrow::Utf16::IsLeadSurrogate(lead_surrogate));
+  FlushPendingSurrogate();
+  // Hold onto the lead surrogate, waiting for a trail surrogate to follow.
+  pending_surrogate_ = lead_surrogate;
+}
+
+
+void RegExpBuilder::AddTrailSurrogate(uc16 trail_surrogate) {
+  DCHECK(unibrow::Utf16::IsTrailSurrogate(trail_surrogate));
+  if (pending_surrogate_ != kNoPendingSurrogate) {
+    uc16 lead_surrogate = pending_surrogate_;
+    pending_surrogate_ = kNoPendingSurrogate;
+    DCHECK(unibrow::Utf16::IsLeadSurrogate(lead_surrogate));
+    uc32 combined =
+        unibrow::Utf16::CombineSurrogatePair(lead_surrogate, trail_surrogate);
+    if (NeedsDesugaringForIgnoreCase(combined)) {
+      AddCharacterClassForDesugaring(combined);
+    } else {
+      ZoneList<uc16> surrogate_pair(2, zone());
+      surrogate_pair.Add(lead_surrogate, zone());
+      surrogate_pair.Add(trail_surrogate, zone());
+      RegExpAtom* atom =
+          new (zone()) RegExpAtom(surrogate_pair.ToConstVector(), flags_);
+      AddAtom(atom);
+    }
+  } else {
+    pending_surrogate_ = trail_surrogate;
+    FlushPendingSurrogate();
+  }
+}
+
+
+void RegExpBuilder::FlushPendingSurrogate() {
+  if (pending_surrogate_ != kNoPendingSurrogate) {
+    DCHECK(unicode());
+    uc32 c = pending_surrogate_;
+    pending_surrogate_ = kNoPendingSurrogate;
+    AddCharacterClassForDesugaring(c);
+  }
+}
+
+
+void RegExpBuilder::FlushCharacters() {
+  FlushPendingSurrogate();
+  pending_empty_ = false;
+  if (characters_ != nullptr) {
+    RegExpTree* atom =
+        new (zone()) RegExpAtom(characters_->ToConstVector(), flags_);
+    characters_ = nullptr;
+    text_.Add(atom, zone());
+    LAST(ADD_ATOM);
+  }
+}
+
+
+void RegExpBuilder::FlushText() {
+  FlushCharacters();
+  int num_text = text_.length();
+  if (num_text == 0) {
+    return;
+  } else if (num_text == 1) {
+    terms_.Add(text_.last(), zone());
+  } else {
+    RegExpText* text = new (zone()) RegExpText(zone());
+    for (int i = 0; i < num_text; i++) text_.Get(i)->AppendToText(text, zone());
+    terms_.Add(text, zone());
+  }
+  text_.Clear();
+}
+
+
+void RegExpBuilder::AddCharacter(uc16 c) {
+  FlushPendingSurrogate();
+  pending_empty_ = false;
+  if (NeedsDesugaringForIgnoreCase(c)) {
+    AddCharacterClassForDesugaring(c);
+  } else {
+    if (characters_ == nullptr) {
+      characters_ = new (zone()) ZoneList<uc16>(4, zone());
+    }
+    characters_->Add(c, zone());
+    LAST(ADD_CHAR);
+  }
+}
+
+
+void RegExpBuilder::AddUnicodeCharacter(uc32 c) {
+  if (c > static_cast<uc32>(unibrow::Utf16::kMaxNonSurrogateCharCode)) {
+    DCHECK(unicode());
+    AddLeadSurrogate(unibrow::Utf16::LeadSurrogate(c));
+    AddTrailSurrogate(unibrow::Utf16::TrailSurrogate(c));
+  } else if (unicode() && unibrow::Utf16::IsLeadSurrogate(c)) {
+    AddLeadSurrogate(c);
+  } else if (unicode() && unibrow::Utf16::IsTrailSurrogate(c)) {
+    AddTrailSurrogate(c);
+  } else {
+    AddCharacter(static_cast<uc16>(c));
+  }
+}
+
+void RegExpBuilder::AddEscapedUnicodeCharacter(uc32 character) {
+  // A lead or trail surrogate parsed via escape sequence will not
+  // pair up with any preceding lead or following trail surrogate.
+  FlushPendingSurrogate();
+  AddUnicodeCharacter(character);
+  FlushPendingSurrogate();
+}
+
+void RegExpBuilder::AddEmpty() { pending_empty_ = true; }
+
+
+void RegExpBuilder::AddCharacterClass(RegExpCharacterClass* cc) {
+  if (NeedsDesugaringForUnicode(cc)) {
+    // With /u, character class needs to be desugared, so it
+    // must be a standalone term instead of being part of a RegExpText.
+    AddTerm(cc);
+  } else {
+    AddAtom(cc);
+  }
+}
+
+void RegExpBuilder::AddCharacterClassForDesugaring(uc32 c) {
+  AddTerm(new (zone()) RegExpCharacterClass(
+      zone(), CharacterRange::List(zone(), CharacterRange::Singleton(c)),
+      flags_));
+}
+
+
+void RegExpBuilder::AddAtom(RegExpTree* term) {
+  if (term->IsEmpty()) {
+    AddEmpty();
+    return;
+  }
+  if (term->IsTextElement()) {
+    FlushCharacters();
+    text_.Add(term, zone());
+  } else {
+    FlushText();
+    terms_.Add(term, zone());
+  }
+  LAST(ADD_ATOM);
+}
+
+
+void RegExpBuilder::AddTerm(RegExpTree* term) {
+  FlushText();
+  terms_.Add(term, zone());
+  LAST(ADD_ATOM);
+}
+
+
+void RegExpBuilder::AddAssertion(RegExpTree* assert) {
+  FlushText();
+  terms_.Add(assert, zone());
+  LAST(ADD_ASSERT);
+}
+
+
+void RegExpBuilder::NewAlternative() { FlushTerms(); }
+
+
+void RegExpBuilder::FlushTerms() {
+  FlushText();
+  int num_terms = terms_.length();
+  RegExpTree* alternative;
+  if (num_terms == 0) {
+    alternative = new (zone()) RegExpEmpty();
+  } else if (num_terms == 1) {
+    alternative = terms_.last();
+  } else {
+    alternative = new (zone()) RegExpAlternative(terms_.GetList(zone()));
+  }
+  alternatives_.Add(alternative, zone());
+  terms_.Clear();
+  LAST(ADD_NONE);
+}
+
+
+bool RegExpBuilder::NeedsDesugaringForUnicode(RegExpCharacterClass* cc) {
+  if (!unicode()) return false;
+  // TODO(yangguo): we could be smarter than this. Case-insensitivity does not
+  // necessarily mean that we need to desugar. It's probably nicer to have a
+  // separate pass to figure out unicode desugarings.
+  if (ignore_case()) return true;
+  ZoneList<CharacterRange>* ranges = cc->ranges(zone());
+  CharacterRange::Canonicalize(ranges);
+  for (int i = ranges->length() - 1; i >= 0; i--) {
+    uc32 from = ranges->at(i).from();
+    uc32 to = ranges->at(i).to();
+    // Check for non-BMP characters.
+    if (to >= kNonBmpStart) return true;
+    // Check for lone surrogates.
+    if (from <= kTrailSurrogateEnd && to >= kLeadSurrogateStart) return true;
+  }
+  return false;
+}
+
+
+bool RegExpBuilder::NeedsDesugaringForIgnoreCase(uc32 c) {
+#ifdef V8_INTL_SUPPORT
+  if (unicode() && ignore_case()) {
+    icu::UnicodeSet set(c, c);
+    set.closeOver(USET_CASE_INSENSITIVE);
+    set.removeAllStrings();
+    return set.size() > 1;
+  }
+  // In the case where ICU is not included, we act as if the unicode flag is
+  // not set, and do not desugar.
+#endif  // V8_INTL_SUPPORT
+  return false;
+}
+
+
+RegExpTree* RegExpBuilder::ToRegExp() {
+  FlushTerms();
+  int num_alternatives = alternatives_.length();
+  if (num_alternatives == 0) return new (zone()) RegExpEmpty();
+  if (num_alternatives == 1) return alternatives_.last();
+  return new (zone()) RegExpDisjunction(alternatives_.GetList(zone()));
+}
+
+bool RegExpBuilder::AddQuantifierToAtom(
+    int min, int max, RegExpQuantifier::QuantifierType quantifier_type) {
+  FlushPendingSurrogate();
+  if (pending_empty_) {
+    pending_empty_ = false;
+    return true;
+  }
+  RegExpTree* atom;
+  if (characters_ != nullptr) {
+    DCHECK(last_added_ == ADD_CHAR);
+    // Last atom was character.
+    Vector<const uc16> char_vector = characters_->ToConstVector();
+    int num_chars = char_vector.length();
+    if (num_chars > 1) {
+      Vector<const uc16> prefix = char_vector.SubVector(0, num_chars - 1);
+      text_.Add(new (zone()) RegExpAtom(prefix, flags_), zone());
+      char_vector = char_vector.SubVector(num_chars - 1, num_chars);
+    }
+    characters_ = nullptr;
+    atom = new (zone()) RegExpAtom(char_vector, flags_);
+    FlushText();
+  } else if (text_.length() > 0) {
+    DCHECK(last_added_ == ADD_ATOM);
+    atom = text_.RemoveLast();
+    FlushText();
+  } else if (terms_.length() > 0) {
+    DCHECK(last_added_ == ADD_ATOM);
+    atom = terms_.RemoveLast();
+    if (atom->IsLookaround()) {
+      // With /u, lookarounds are not quantifiable.
+      if (unicode()) return false;
+      // Lookbehinds are not quantifiable.
+      if (atom->AsLookaround()->type() == RegExpLookaround::LOOKBEHIND) {
+        return false;
+      }
+    }
+    if (atom->max_match() == 0) {
+      // Guaranteed to only match an empty string.
+      LAST(ADD_TERM);
+      if (min == 0) {
+        return true;
+      }
+      terms_.Add(atom, zone());
+      return true;
+    }
+  } else {
+    // Only call immediately after adding an atom or character!
+    UNREACHABLE();
+  }
+  terms_.Add(new (zone()) RegExpQuantifier(min, max, quantifier_type, atom),
+             zone());
+  LAST(ADD_TERM);
+  return true;
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-parser.h b/js/src/regexp/regexp-parser.h
new file mode 100644
index 0000000000..91677d6c35
--- /dev/null
+++ b/js/src/regexp/regexp-parser.h
@@ -0,0 +1,359 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_PARSER_H_
+#define V8_REGEXP_REGEXP_PARSER_H_
+
+#include "regexp/regexp-ast.h"
+
+namespace v8 {
+namespace internal {
+
+struct RegExpCompileData;
+
+// A BufferedZoneList is an automatically growing list, just like (and backed
+// by) a ZoneList, that is optimized for the case of adding and removing
+// a single element. The last element added is stored outside the backing list,
+// and if no more than one element is ever added, the ZoneList isn't even
+// allocated.
+// Elements must not be nullptr pointers.
+template <typename T, int initial_size>
+class BufferedZoneList {
+ public:
+  BufferedZoneList() : list_(nullptr), last_(nullptr) {}
+
+  // Adds element at end of list. This element is buffered and can
+  // be read using last() or removed using RemoveLast until a new Add or until
+  // RemoveLast or GetList has been called.
+  void Add(T* value, Zone* zone) {
+    if (last_ != nullptr) {
+      if (list_ == nullptr) {
+        list_ = new (zone) ZoneList<T*>(initial_size, zone);
+      }
+      list_->Add(last_, zone);
+    }
+    last_ = value;
+  }
+
+  T* last() {
+    DCHECK(last_ != nullptr);
+    return last_;
+  }
+
+  T* RemoveLast() {
+    DCHECK(last_ != nullptr);
+    T* result = last_;
+    if ((list_ != nullptr) && (list_->length() > 0))
+      last_ = list_->RemoveLast();
+    else
+      last_ = nullptr;
+    return result;
+  }
+
+  T* Get(int i) {
+    DCHECK((0 <= i) && (i < length()));
+    if (list_ == nullptr) {
+      DCHECK_EQ(0, i);
+      return last_;
+    } else {
+      if (i == list_->length()) {
+        DCHECK(last_ != nullptr);
+        return last_;
+      } else {
+        return list_->at(i);
+      }
+    }
+  }
+
+  void Clear() {
+    list_ = nullptr;
+    last_ = nullptr;
+  }
+
+  int length() {
+    int length = (list_ == nullptr) ? 0 : list_->length();
+    return length + ((last_ == nullptr) ? 0 : 1);
+  }
+
+  ZoneList<T*>* GetList(Zone* zone) {
+    if (list_ == nullptr) {
+      list_ = new (zone) ZoneList<T*>(initial_size, zone);
+    }
+    if (last_ != nullptr) {
+      list_->Add(last_, zone);
+      last_ = nullptr;
+    }
+    return list_;
+  }
+
+ private:
+  ZoneList<T*>* list_;
+  T* last_;
+};
+
+
+// Accumulates RegExp atoms and assertions into lists of terms and alternatives.
+class RegExpBuilder : public ZoneObject {
+ public:
+  RegExpBuilder(Zone* zone, JSRegExp::Flags flags);
+  void AddCharacter(uc16 character);
+  void AddUnicodeCharacter(uc32 character);
+  void AddEscapedUnicodeCharacter(uc32 character);
+  // "Adds" an empty expression. Does nothing except consume a
+  // following quantifier
+  void AddEmpty();
+  void AddCharacterClass(RegExpCharacterClass* cc);
+  void AddCharacterClassForDesugaring(uc32 c);
+  void AddAtom(RegExpTree* tree);
+  void AddTerm(RegExpTree* tree);
+  void AddAssertion(RegExpTree* tree);
+  void NewAlternative();  // '|'
+  bool AddQuantifierToAtom(int min, int max,
+                           RegExpQuantifier::QuantifierType type);
+  void FlushText();
+  RegExpTree* ToRegExp();
+  JSRegExp::Flags flags() const { return flags_; }
+  void set_flags(JSRegExp::Flags flags) { flags_ = flags; }
+
+  bool ignore_case() const { return (flags_ & JSRegExp::kIgnoreCase) != 0; }
+  bool multiline() const { return (flags_ & JSRegExp::kMultiline) != 0; }
+  bool dotall() const { return (flags_ & JSRegExp::kDotAll) != 0; }
+
+ private:
+  static const uc16 kNoPendingSurrogate = 0;
+  void AddLeadSurrogate(uc16 lead_surrogate);
+  void AddTrailSurrogate(uc16 trail_surrogate);
+  void FlushPendingSurrogate();
+  void FlushCharacters();
+  void FlushTerms();
+  bool NeedsDesugaringForUnicode(RegExpCharacterClass* cc);
+  bool NeedsDesugaringForIgnoreCase(uc32 c);
+  Zone* zone() const { return zone_; }
+  bool unicode() const { return (flags_ & JSRegExp::kUnicode) != 0; }
+
+  Zone* zone_;
+  bool pending_empty_;
+  JSRegExp::Flags flags_;
+  ZoneList<uc16>* characters_;
+  uc16 pending_surrogate_;
+  BufferedZoneList<RegExpTree, 2> terms_;
+  BufferedZoneList<RegExpTree, 2> text_;
+  BufferedZoneList<RegExpTree, 2> alternatives_;
+#ifdef DEBUG
+  enum { ADD_NONE, ADD_CHAR, ADD_TERM, ADD_ASSERT, ADD_ATOM } last_added_;
+#define LAST(x) last_added_ = x;
+#else
+#define LAST(x)
+#endif
+};
+
+class V8_EXPORT_PRIVATE RegExpParser {
+ public:
+  RegExpParser(FlatStringReader* in, Handle<String>* error,
+               JSRegExp::Flags flags, Isolate* isolate, Zone* zone);
+
+  static bool ParseRegExp(Isolate* isolate, Zone* zone, FlatStringReader* input,
+                          JSRegExp::Flags flags, RegExpCompileData* result);
+
+  RegExpTree* ParsePattern();
+  RegExpTree* ParseDisjunction();
+  RegExpTree* ParseGroup();
+
+  // Parses a {...,...} quantifier and stores the range in the given
+  // out parameters.
+  bool ParseIntervalQuantifier(int* min_out, int* max_out);
+
+  // Parses and returns a single escaped character.  The character
+  // must not be 'b' or 'B' since they are usually handle specially.
+  uc32 ParseClassCharacterEscape();
+
+  // Checks whether the following is a length-digit hexadecimal number,
+  // and sets the value if it is.
+  bool ParseHexEscape(int length, uc32* value);
+  bool ParseUnicodeEscape(uc32* value);
+  bool ParseUnlimitedLengthHexNumber(int max_value, uc32* value);
+
+  bool ParsePropertyClassName(std::vector<char>* name_1,
+                              std::vector<char>* name_2);
+  bool AddPropertyClassRange(ZoneList<CharacterRange>* add_to, bool negate,
+                             const std::vector<char>& name_1,
+                             const std::vector<char>& name_2);
+
+  RegExpTree* GetPropertySequence(const std::vector<char>& name_1);
+  RegExpTree* ParseCharacterClass(const RegExpBuilder* state);
+
+  uc32 ParseOctalLiteral();
+
+  // Tries to parse the input as a back reference.  If successful it
+  // stores the result in the output parameter and returns true.  If
+  // it fails it will push back the characters read so the same characters
+  // can be reparsed.
+  bool ParseBackReferenceIndex(int* index_out);
+
+  // Parse inside a class. Either add escaped class to the range, or return
+  // false and pass parsed single character through |char_out|.
+  void ParseClassEscape(ZoneList<CharacterRange>* ranges, Zone* zone,
+                        bool add_unicode_case_equivalents, uc32* char_out,
+                        bool* is_class_escape);
+
+  char ParseClassEscape();
+
+  RegExpTree* ReportError(Vector<const char> message);
+  void Advance();
+  void Advance(int dist);
+  void Reset(int pos);
+
+  // Reports whether the pattern might be used as a literal search string.
+  // Only use if the result of the parse is a single atom node.
+  bool simple();
+  bool contains_anchor() { return contains_anchor_; }
+  void set_contains_anchor() { contains_anchor_ = true; }
+  int captures_started() { return captures_started_; }
+  int position() { return next_pos_ - 1; }
+  bool failed() { return failed_; }
+  // The Unicode flag can't be changed using in-regexp syntax, so it's OK to
+  // just read the initial flag value here.
+  bool unicode() const { return (top_level_flags_ & JSRegExp::kUnicode) != 0; }
+
+  static bool IsSyntaxCharacterOrSlash(uc32 c);
+
+  static const uc32 kEndMarker = (1 << 21);
+
+ private:
+  enum SubexpressionType {
+    INITIAL,
+    CAPTURE,  // All positive values represent captures.
+    POSITIVE_LOOKAROUND,
+    NEGATIVE_LOOKAROUND,
+    GROUPING
+  };
+
+  class RegExpParserState : public ZoneObject {
+   public:
+    // Push a state on the stack.
+    RegExpParserState(RegExpParserState* previous_state,
+                      SubexpressionType group_type,
+                      RegExpLookaround::Type lookaround_type,
+                      int disjunction_capture_index,
+                      const ZoneVector<uc16>* capture_name,
+                      JSRegExp::Flags flags, Zone* zone)
+        : previous_state_(previous_state),
+          builder_(new (zone) RegExpBuilder(zone, flags)),
+          group_type_(group_type),
+          lookaround_type_(lookaround_type),
+          disjunction_capture_index_(disjunction_capture_index),
+          capture_name_(capture_name) {}
+    // Parser state of containing expression, if any.
+    RegExpParserState* previous_state() const { return previous_state_; }
+    bool IsSubexpression() { return previous_state_ != nullptr; }
+    // RegExpBuilder building this regexp's AST.
+    RegExpBuilder* builder() const { return builder_; }
+    // Type of regexp being parsed (parenthesized group or entire regexp).
+    SubexpressionType group_type() const { return group_type_; }
+    // Lookahead or Lookbehind.
+    RegExpLookaround::Type lookaround_type() const { return lookaround_type_; }
+    // Index in captures array of first capture in this sub-expression, if any.
+    // Also the capture index of this sub-expression itself, if group_type
+    // is CAPTURE.
+    int capture_index() const { return disjunction_capture_index_; }
+    // The name of the current sub-expression, if group_type is CAPTURE. Only
+    // used for named captures.
+    const ZoneVector<uc16>* capture_name() const { return capture_name_; }
+
+    bool IsNamedCapture() const { return capture_name_ != nullptr; }
+
+    // Check whether the parser is inside a capture group with the given index.
+    bool IsInsideCaptureGroup(int index);
+    // Check whether the parser is inside a capture group with the given name.
+    bool IsInsideCaptureGroup(const ZoneVector<uc16>* name);
+
+   private:
+    // Linked list implementation of stack of states.
+    RegExpParserState* const previous_state_;
+    // Builder for the stored disjunction.
+    RegExpBuilder* const builder_;
+    // Stored disjunction type (capture, look-ahead or grouping), if any.
+    const SubexpressionType group_type_;
+    // Stored read direction.
+    const RegExpLookaround::Type lookaround_type_;
+    // Stored disjunction's capture index (if any).
+    const int disjunction_capture_index_;
+    // Stored capture name (if any).
+    const ZoneVector<uc16>* const capture_name_;
+  };
+
+  // Return the 1-indexed RegExpCapture object, allocate if necessary.
+  RegExpCapture* GetCapture(int index);
+
+  // Creates a new named capture at the specified index. Must be called exactly
+  // once for each named capture. Fails if a capture with the same name is
+  // encountered.
+  bool CreateNamedCaptureAtIndex(const ZoneVector<uc16>* name, int index);
+
+  // Parses the name of a capture group (?<name>pattern). The name must adhere
+  // to IdentifierName in the ECMAScript standard.
+  const ZoneVector<uc16>* ParseCaptureGroupName();
+
+  bool ParseNamedBackReference(RegExpBuilder* builder,
+                               RegExpParserState* state);
+  RegExpParserState* ParseOpenParenthesis(RegExpParserState* state);
+
+  // After the initial parsing pass, patch corresponding RegExpCapture objects
+  // into all RegExpBackReferences. This is done after initial parsing in order
+  // to avoid complicating cases in which references comes before the capture.
+  void PatchNamedBackReferences();
+
+  Handle<FixedArray> CreateCaptureNameMap();
+
+  // Returns true iff the pattern contains named captures. May call
+  // ScanForCaptures to look ahead at the remaining pattern.
+  bool HasNamedCaptures();
+
+  Isolate* isolate() { return isolate_; }
+  Zone* zone() const { return zone_; }
+
+  uc32 current() { return current_; }
+  bool has_more() { return has_more_; }
+  bool has_next() { return next_pos_ < in()->length(); }
+  uc32 Next();
+  template <bool update_position>
+  uc32 ReadNext();
+  FlatStringReader* in() { return in_; }
+  void ScanForCaptures();
+
+  struct RegExpCaptureNameLess {
+    bool operator()(const RegExpCapture* lhs, const RegExpCapture* rhs) const {
+      DCHECK_NOT_NULL(lhs);
+      DCHECK_NOT_NULL(rhs);
+      return *lhs->name() < *rhs->name();
+    }
+  };
+
+  Isolate* isolate_;
+  Zone* zone_;
+  Handle<String>* error_;
+  ZoneList<RegExpCapture*>* captures_;
+  ZoneSet<RegExpCapture*, RegExpCaptureNameLess>* named_captures_;
+  ZoneList<RegExpBackReference*>* named_back_references_;
+  FlatStringReader* in_;
+  uc32 current_;
+  // These are the flags specified outside the regexp syntax ie after the
+  // terminating '/' or in the second argument to the constructor.  The current
+  // flags are stored on the RegExpBuilder.
+  JSRegExp::Flags top_level_flags_;
+  int next_pos_;
+  int captures_started_;
+  int capture_count_;  // Only valid after we have scanned for captures.
+  bool has_more_;
+  bool simple_;
+  bool contains_anchor_;
+  bool is_scanned_for_captures_;
+  bool has_named_captures_;  // Only valid after we have scanned for captures.
+  bool failed_;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_PARSER_H_
diff --git a/js/src/regexp/regexp-stack.cc b/js/src/regexp/regexp-stack.cc
new file mode 100644
index 0000000000..b8819e48b6
--- /dev/null
+++ b/js/src/regexp/regexp-stack.cc
@@ -0,0 +1,97 @@
+// Copyright 2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "regexp/regexp-stack.h"
+
+
+namespace v8 {
+namespace internal {
+
+RegExpStackScope::RegExpStackScope(Isolate* isolate)
+    : regexp_stack_(isolate->regexp_stack()) {
+  // Initialize, if not already initialized.
+  regexp_stack_->EnsureCapacity(0);
+}
+
+
+RegExpStackScope::~RegExpStackScope() {
+  // Reset the buffer if it has grown.
+  regexp_stack_->Reset();
+}
+
+RegExpStack::RegExpStack() : thread_local_(this), isolate_(nullptr) {}
+
+RegExpStack::~RegExpStack() { thread_local_.FreeAndInvalidate(); }
+
+char* RegExpStack::ArchiveStack(char* to) {
+  if (!thread_local_.owns_memory_) {
+    // Force dynamic stacks prior to archiving. Any growth will do. A dynamic
+    // stack is needed because stack archival & restoration rely on `memory_`
+    // pointing at a fixed-location backing store, whereas the static stack is
+    // tied to a RegExpStack instance.
+    EnsureCapacity(thread_local_.memory_size_ + 1);
+    DCHECK(thread_local_.owns_memory_);
+  }
+
+  size_t size = sizeof(thread_local_);
+  MemCopy(reinterpret_cast<void*>(to), &thread_local_, size);
+  thread_local_ = ThreadLocal(this);
+  return to + size;
+}
+
+
+char* RegExpStack::RestoreStack(char* from) {
+  size_t size = sizeof(thread_local_);
+  MemCopy(&thread_local_, reinterpret_cast<void*>(from), size);
+  return from + size;
+}
+
+void RegExpStack::Reset() { thread_local_.ResetToStaticStack(this); }
+
+void RegExpStack::ThreadLocal::ResetToStaticStack(RegExpStack* regexp_stack) {
+  if (owns_memory_) DeleteArray(memory_);
+
+  memory_ = regexp_stack->static_stack_;
+  memory_top_ = regexp_stack->static_stack_ + kStaticStackSize;
+  memory_size_ = kStaticStackSize;
+  limit_ = reinterpret_cast<Address>(regexp_stack->static_stack_) +
+           kStackLimitSlack * kSystemPointerSize;
+  owns_memory_ = false;
+}
+
+void RegExpStack::ThreadLocal::FreeAndInvalidate() {
+  if (owns_memory_) DeleteArray(memory_);
+
+  // This stack may not be used after being freed. Just reset to invalid values
+  // to ensure we don't accidentally use old memory areas.
+  memory_ = nullptr;
+  memory_top_ = nullptr;
+  memory_size_ = 0;
+  limit_ = kMemoryTop;
+}
+
+Address RegExpStack::EnsureCapacity(size_t size) {
+  if (size > kMaximumStackSize) return kNullAddress;
+  if (size < kMinimumDynamicStackSize) size = kMinimumDynamicStackSize;
+  if (thread_local_.memory_size_ < size) {
+    byte* new_memory = NewArray<byte>(size);
+    if (thread_local_.memory_size_ > 0) {
+      // Copy original memory into top of new memory.
+      MemCopy(new_memory + size - thread_local_.memory_size_,
+              thread_local_.memory_, thread_local_.memory_size_);
+      if (thread_local_.owns_memory_) DeleteArray(thread_local_.memory_);
+    }
+    thread_local_.memory_ = new_memory;
+    thread_local_.memory_top_ = new_memory + size;
+    thread_local_.memory_size_ = size;
+    thread_local_.limit_ = reinterpret_cast<Address>(new_memory) +
+                           kStackLimitSlack * kSystemPointerSize;
+    thread_local_.owns_memory_ = true;
+  }
+  return reinterpret_cast<Address>(thread_local_.memory_top_);
+}
+
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/regexp/regexp-stack.h b/js/src/regexp/regexp-stack.h
new file mode 100644
index 0000000000..2c2cf26304
--- /dev/null
+++ b/js/src/regexp/regexp-stack.h
@@ -0,0 +1,140 @@
+// Copyright 2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_STACK_H_
+#define V8_REGEXP_REGEXP_STACK_H_
+
+
+namespace v8 {
+namespace internal {
+
+class RegExpStack;
+
+// Maintains a per-v8thread stack area that can be used by irregexp
+// implementation for its backtracking stack.
+// Since there is only one stack area, the Irregexp implementation is not
+// re-entrant. I.e., no regular expressions may be executed in the same thread
+// during a preempted Irregexp execution.
+class RegExpStackScope {
+ public:
+  // Create and delete an instance to control the life-time of a growing stack.
+
+  // Initializes the stack memory area if necessary.
+  explicit RegExpStackScope(Isolate* isolate);
+  ~RegExpStackScope();  // Releases the stack if it has grown.
+
+  RegExpStack* stack() const { return regexp_stack_; }
+
+ private:
+  RegExpStack* regexp_stack_;
+
+  DISALLOW_COPY_AND_ASSIGN(RegExpStackScope);
+};
+
+
+class RegExpStack {
+ public:
+  // Number of allocated locations on the stack below the limit.
+  // No sequence of pushes must be longer that this without doing a stack-limit
+  // check.
+  static constexpr int kStackLimitSlack = 32;
+
+  // Gives the top of the memory used as stack.
+  Address stack_base() {
+    DCHECK_NE(0, thread_local_.memory_size_);
+    DCHECK_EQ(thread_local_.memory_top_,
+              thread_local_.memory_ + thread_local_.memory_size_);
+    return reinterpret_cast<Address>(thread_local_.memory_top_);
+  }
+
+  // The total size of the memory allocated for the stack.
+  size_t stack_capacity() { return thread_local_.memory_size_; }
+
+  // If the stack pointer gets below the limit, we should react and
+  // either grow the stack or report an out-of-stack exception.
+  // There is only a limited number of locations below the stack limit,
+  // so users of the stack should check the stack limit during any
+  // sequence of pushes longer that this.
+  Address* limit_address_address() { return &(thread_local_.limit_); }
+
+  // Ensures that there is a memory area with at least the specified size.
+  // If passing zero, the default/minimum size buffer is allocated.
+  Address EnsureCapacity(size_t size);
+
+  // Thread local archiving.
+  static constexpr int ArchiveSpacePerThread() {
+    return static_cast<int>(sizeof(ThreadLocal));
+  }
+  char* ArchiveStack(char* to);
+  char* RestoreStack(char* from);
+  void FreeThreadResources() { thread_local_.ResetToStaticStack(this); }
+
+  // Maximal size of allocated stack area.
+  static constexpr size_t kMaximumStackSize = 64 * MB;
+
+ private:
+  RegExpStack();
+  ~RegExpStack();
+
+  // Artificial limit used when the thread-local state has been destroyed.
+  static const Address kMemoryTop =
+      static_cast<Address>(static_cast<uintptr_t>(-1));
+
+  // Minimal size of dynamically-allocated stack area.
+  static constexpr size_t kMinimumDynamicStackSize = 1 * KB;
+
+  // In addition to dynamically-allocated, variable-sized stacks, we also have
+  // a statically allocated and sized area that is used whenever no dynamic
+  // stack is allocated. This guarantees that a stack is always available and
+  // we can skip availability-checks later on.
+  // It's double the slack size to ensure that we have a bit of breathing room
+  // before NativeRegExpMacroAssembler::GrowStack must be called.
+  static constexpr size_t kStaticStackSize =
+      2 * kStackLimitSlack * kSystemPointerSize;
+  byte static_stack_[kStaticStackSize] = {0};
+
+  STATIC_ASSERT(kStaticStackSize <= kMaximumStackSize);
+
+  // Structure holding the allocated memory, size and limit.
+  struct ThreadLocal {
+    explicit ThreadLocal(RegExpStack* regexp_stack) {
+      ResetToStaticStack(regexp_stack);
+    }
+
+    // If memory_size_ > 0 then memory_ and memory_top_ must be non-nullptr
+    // and memory_top_ = memory_ + memory_size_
+    byte* memory_ = nullptr;
+    byte* memory_top_ = nullptr;
+    size_t memory_size_ = 0;
+    Address limit_ = kNullAddress;
+    bool owns_memory_ = false;  // Whether memory_ is owned and must be freed.
+
+    void ResetToStaticStack(RegExpStack* regexp_stack);
+    void FreeAndInvalidate();
+  };
+
+  // Address of top of memory used as stack.
+  Address memory_top_address_address() {
+    return reinterpret_cast<Address>(&thread_local_.memory_top_);
+  }
+
+  // Resets the buffer if it has grown beyond the default/minimum size.
+  // After this, the buffer is either the default size, or it is empty, so
+  // you have to call EnsureCapacity before using it again.
+  void Reset();
+
+  ThreadLocal thread_local_;
+  Isolate* isolate_;
+
+  friend class ExternalReference;
+  friend class Isolate;
+  friend class RegExpStackScope;
+
+  DISALLOW_COPY_AND_ASSIGN(RegExpStack);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_STACK_H_
diff --git a/js/src/regexp/regexp.h b/js/src/regexp/regexp.h
new file mode 100644
index 0000000000..1ee10da5c4
--- /dev/null
+++ b/js/src/regexp/regexp.h
@@ -0,0 +1,189 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_H_
+#define V8_REGEXP_REGEXP_H_
+
+
+namespace v8 {
+namespace internal {
+
+class RegExpNode;
+class RegExpTree;
+
+enum class RegExpCompilationTarget : int { kBytecode, kNative };
+
+// TODO(jgruber): Do not expose in regexp.h.
+// TODO(jgruber): Consider splitting between ParseData and CompileData.
+struct RegExpCompileData {
+  // The parsed AST as produced by the RegExpParser.
+  RegExpTree* tree = nullptr;
+
+  // The compiled Node graph as produced by RegExpTree::ToNode methods.
+  RegExpNode* node = nullptr;
+
+  // Either the generated code as produced by the compiler or a trampoline
+  // to the interpreter.
+  Object code;
+
+  // True, iff the pattern is a 'simple' atom with zero captures. In other
+  // words, the pattern consists of a string with no metacharacters and special
+  // regexp features, and can be implemented as a standard string search.
+  bool simple = true;
+
+  // True, iff the pattern is anchored at the start of the string with '^'.
+  bool contains_anchor = false;
+
+  // Only use if the pattern contains named captures. If so, this contains a
+  // mapping of capture names to capture indices.
+  Handle<FixedArray> capture_name_map;
+
+  // The error message. Only used if an error occurred during parsing or
+  // compilation.
+  Handle<String> error;
+
+  // The number of capture groups, without the global capture \0.
+  int capture_count = 0;
+
+  // The number of registers used by the generated code.
+  int register_count = 0;
+
+  // The compilation target (bytecode or native code).
+  RegExpCompilationTarget compilation_target;
+};
+
+class RegExp final : public AllStatic {
+ public:
+  // Whether the irregexp engine generates interpreter bytecode.
+  static bool CanGenerateBytecode() {
+    return FLAG_regexp_interpret_all || FLAG_regexp_tier_up;
+  }
+
+  // Parses the RegExp pattern and prepares the JSRegExp object with
+  // generic data and choice of implementation - as well as what
+  // the implementation wants to store in the data field.
+  // Returns false if compilation fails.
+  V8_WARN_UNUSED_RESULT static MaybeHandle<Object> Compile(
+      Isolate* isolate, Handle<JSRegExp> re, Handle<String> pattern,
+      JSRegExp::Flags flags, uint32_t backtrack_limit);
+
+  enum CallOrigin : int {
+    kFromRuntime = 0,
+    kFromJs = 1,
+  };
+
+  // See ECMA-262 section 15.10.6.2.
+  // This function calls the garbage collector if necessary.
+  V8_EXPORT_PRIVATE V8_WARN_UNUSED_RESULT static MaybeHandle<Object> Exec(
+      Isolate* isolate, Handle<JSRegExp> regexp, Handle<String> subject,
+      int index, Handle<RegExpMatchInfo> last_match_info);
+
+  // Integral return values used throughout regexp code layers.
+  static constexpr int kInternalRegExpFailure = 0;
+  static constexpr int kInternalRegExpSuccess = 1;
+  static constexpr int kInternalRegExpException = -1;
+  static constexpr int kInternalRegExpRetry = -2;
+
+  enum IrregexpResult : int32_t {
+    RE_FAILURE = kInternalRegExpFailure,
+    RE_SUCCESS = kInternalRegExpSuccess,
+    RE_EXCEPTION = kInternalRegExpException,
+  };
+
+  // Prepare a RegExp for being executed one or more times (using
+  // IrregexpExecOnce) on the subject.
+  // This ensures that the regexp is compiled for the subject, and that
+  // the subject is flat.
+  // Returns the number of integer spaces required by IrregexpExecOnce
+  // as its "registers" argument.  If the regexp cannot be compiled,
+  // an exception is set as pending, and this function returns negative.
+  static int IrregexpPrepare(Isolate* isolate, Handle<JSRegExp> regexp,
+                             Handle<String> subject);
+
+  // Set last match info.  If match is nullptr, then setting captures is
+  // omitted.
+  static Handle<RegExpMatchInfo> SetLastMatchInfo(
+      Isolate* isolate, Handle<RegExpMatchInfo> last_match_info,
+      Handle<String> subject, int capture_count, int32_t* match);
+
+  V8_EXPORT_PRIVATE static bool CompileForTesting(Isolate* isolate, Zone* zone,
+                                                  RegExpCompileData* input,
+                                                  JSRegExp::Flags flags,
+                                                  Handle<String> pattern,
+                                                  Handle<String> sample_subject,
+                                                  bool is_one_byte);
+
+  V8_EXPORT_PRIVATE static void DotPrintForTesting(const char* label,
+                                                   RegExpNode* node);
+
+  static const int kRegExpTooLargeToOptimize = 20 * KB;
+};
+
+// Uses a special global mode of irregexp-generated code to perform a global
+// search and return multiple results at once. As such, this is essentially an
+// iterator over multiple results (retrieved batch-wise in advance).
+class RegExpGlobalCache final {
+ public:
+  RegExpGlobalCache(Handle<JSRegExp> regexp, Handle<String> subject,
+                    Isolate* isolate);
+
+  ~RegExpGlobalCache();
+
+  // Fetch the next entry in the cache for global regexp match results.
+  // This does not set the last match info.  Upon failure, nullptr is
+  // returned. The cause can be checked with Result().  The previous result is
+  // still in available in memory when a failure happens.
+  int32_t* FetchNext();
+
+  int32_t* LastSuccessfulMatch();
+
+  bool HasException() { return num_matches_ < 0; }
+
+ private:
+  int AdvanceZeroLength(int last_index);
+
+  int num_matches_;
+  int max_matches_;
+  int current_match_index_;
+  int registers_per_match_;
+  // Pointer to the last set of captures.
+  int32_t* register_array_;
+  int register_array_size_;
+  Handle<JSRegExp> regexp_;
+  Handle<String> subject_;
+  Isolate* isolate_;
+};
+
+// Caches results for specific regexp queries on the isolate. At the time of
+// writing, this is used during global calls to RegExp.prototype.exec and
+// @@split.
+class RegExpResultsCache final : public AllStatic {
+ public:
+  enum ResultsCacheType { REGEXP_MULTIPLE_INDICES, STRING_SPLIT_SUBSTRINGS };
+
+  // Attempt to retrieve a cached result.  On failure, 0 is returned as a Smi.
+  // On success, the returned result is guaranteed to be a COW-array.
+  static Object Lookup(Heap* heap, String key_string, Object key_pattern,
+                       FixedArray* last_match_out, ResultsCacheType type);
+  // Attempt to add value_array to the cache specified by type.  On success,
+  // value_array is turned into a COW-array.
+  static void Enter(Isolate* isolate, Handle<String> key_string,
+                    Handle<Object> key_pattern, Handle<FixedArray> value_array,
+                    Handle<FixedArray> last_match_cache, ResultsCacheType type);
+  static void Clear(FixedArray cache);
+
+  static constexpr int kRegExpResultsCacheSize = 0x100;
+
+ private:
+  static constexpr int kStringOffset = 0;
+  static constexpr int kPatternOffset = 1;
+  static constexpr int kArrayOffset = 2;
+  static constexpr int kLastMatchOffset = 3;
+  static constexpr int kArrayEntriesPerCacheEntry = 4;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_H_
diff --git a/js/src/regexp/special-case.h b/js/src/regexp/special-case.h
new file mode 100644
index 0000000000..1ccec5d31a
--- /dev/null
+++ b/js/src/regexp/special-case.h
@@ -0,0 +1,79 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_SPECIAL_CASE_H_
+#define V8_REGEXP_SPECIAL_CASE_H_
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/uversion.h"
+namespace U_ICU_NAMESPACE {
+class UnicodeSet;
+}  //  namespace U_ICU_NAMESPACE
+
+namespace v8 {
+namespace internal {
+
+// Functions to build special sets of Unicode characters that need special
+// handling under "i" mode that cannot use closeOver(USET_CASE_INSENSITIVE).
+//
+// For the characters in the "ignore set", the process should not treat other
+// characters in the result of closeOver(USET_CASE_INSENSITIVE) as case
+// equivlant under the ECMA262 RegExp "i" mode because these characters are
+// uppercase themselves that no other characters in the set uppercase to.
+//
+// For the characters in the "special add set", the proecess should add only
+// those characters in the result of closeOver(USET_CASE_INSENSITIVE) which is
+// not uppercase characters as case equivlant under the ECMA262 RegExp "i" mode
+// and also that ONE uppercase character that other non uppercase character
+// uppercase into to the set. Other uppercase characters in the result of
+// closeOver(USET_CASE_INSENSITIVE) should not be considered because ECMA262
+// RegExp "i" mode consider two characters as "case equivlant" if both
+// characters uppercase to the same character.
+//
+// For example, consider the following case equivalent set defined by Unicode
+// standard. Notice there are more than one uppercase characters in this set:
+//  U+212B Å Angstrom Sign - an uppercase character.
+//  U+00C5 Å Latin Capital Letter A with Ring Above - an uppercase character.
+//  U+00E5 å Latin Small Letter A with Ring Above - a lowercase character which
+//    uppercase to U+00C5.
+// In this case equivlant set is a special set and need special handling while
+// considering "case equivlant" under the ECMA262 RegExp "i" mode which is
+// different than Unicode Standard:
+//  * U+212B should be included into the "ignore" set because there are no other
+//    characters, under the ECMA262 "i" mode, are considered as "case equivlant"
+//    to it because U+212B is itself an uppercase but neither U+00C5 nor U+00E5
+//    uppercase to U+212B.
+//  * U+00C5 and U+00E5 will both be included into the "special add" set. While
+//    calculate the "equivlant set" under ECMA262 "i" mode, the process will
+//    add U+00E5, because it is not an uppercase character in the set. The
+//    process will also add U+00C5, because it is the uppercase character which
+//    other non uppercase character, U+00C5, uppercase into.
+//
+// For characters not included in "ignore set" and "special add set", the
+// process will just use closeOver(USET_CASE_INSENSITIVE) to calcualte, which is
+// much faster.
+//
+// Under Unicode 12.0, there are only 7 characters in the "special add set" and
+// 4 characters in "ignore set" so even the special add process is slower, it is
+// limited to a small set of cases only.
+//
+// The implementation of these two function will be generated by calling ICU
+// icu::UnicodeSet during the build time into gen/src/regexp/special-case.cc by
+// the code in src/regexp/gen-regexp-special-case.cc.
+//
+// These two function will be used with LazyInstance<> template to generate
+// global sharable set to reduce memory usage and speed up performance.
+
+// Function to build and return the Ignore set.
+icu::UnicodeSet BuildIgnoreSet();
+
+// Function to build and return the Special Add set.
+icu::UnicodeSet BuildSpecialAddSet();
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTL_SUPPORT
+
+#endif  // V8_REGEXP_SPECIAL_CASE_H_
diff --git a/js/src/regexp/update-headers.py b/js/src/regexp/update-headers.py
new file mode 100644
index 0000000000..0cff9d6aee
--- /dev/null
+++ b/js/src/regexp/update-headers.py
@@ -0,0 +1,38 @@
+#!/usr/bin/env python
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# This script modifies V8 regexp source files to make them suitable for
+# inclusion in SpiderMonkey. Specifically, it:
+#
+# 1. Rewrites all #includes of V8 regexp headers to point to their location in
+#    the SM tree: src/regexp/* --> regexp/*
+# 2. Removes all #includes of other V8 src/* headers. The required definitions
+#    will be provided by regexp-shim.h.
+#
+# Usage:
+#    cd js/src/regexp
+#    find . -name "*.h" -o -name "*.cc" | xargs ./update_headers.py
+#
+
+import fileinput
+import re
+import sys
+
+# 1. Rewrite includes of V8 regexp headers
+regexp_include = re.compile('#include "src/regexp')
+regexp_include_new = '#include "regexp'
+
+# 2. Remove includes of other V8 headers
+other_include = re.compile('#include "src/')
+
+for line in fileinput.input(inplace=1):
+    if regexp_include.search(line):
+        sys.stdout.write(re.sub(regexp_include, regexp_include_new, line))
+    elif other_include.search(line):
+        pass
+    else:
+        sys.stdout.write(line)

From a3bc68b4e92b4bb9d3ee0461c4c9e84b0b0c2e2d Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Wed, 4 Nov 2020 20:26:51 -0500
Subject: [PATCH 30/30] Issue #1677 - Part 2: Add build files

---
 js/moz.configure        | 13 +++++++++++++
 js/src/moz.build        |  3 +++
 js/src/regexp/moz.build | 31 +++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+)
 create mode 100644 js/src/regexp/moz.build

diff --git a/js/moz.configure b/js/moz.configure
index 7687731f99..3bbaf01a3b 100644
--- a/js/moz.configure
+++ b/js/moz.configure
@@ -246,3 +246,16 @@ with only_when('--enable-compile-environment'):
 
     set_config('LIBFUZZER', enable_libfuzzer)
     set_define('LIBFUZZER', enable_libfuzzer)
+
+# Initial support for new regexp engine
+# ==================================================
+
+js_option('--enable-new-regexp', default=False, help='Enable new regexp engine')
+
+@depends('--enable-new-regexp')
+def enable_new_regexp(value):
+    if value:
+        return True
+
+set_config('JS_NEW_REGEXP', enable_new_regexp)
+set_define('JS_NEW_REGEXP', enable_new_regexp)
diff --git a/js/src/moz.build b/js/src/moz.build
index f9e5233a9f..a6ee7b7375 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -122,6 +122,9 @@ if CONFIG['JS_HAS_CTYPES']:
 if CONFIG['JS_BUNDLED_EDITLINE']:
     DIRS += ['editline']
 
+if CONFIG['JS_NEW_REGEXP']:
+    DIRS += ['regexp']
+
 if not CONFIG['JS_DISABLE_SHELL']:
     DIRS += ['shell']
 
diff --git a/js/src/regexp/moz.build b/js/src/regexp/moz.build
new file mode 100644
index 0000000000..f8fc99921e
--- /dev/null
+++ b/js/src/regexp/moz.build
@@ -0,0 +1,31 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+include('../js-config.mozbuild')
+include('../js-cxxflags.mozbuild')
+
+FINAL_LIBRARY = "js"
+
+# Includes should be relative to parent path
+LOCAL_INCLUDES += ["!..", ".."]
+
+SOURCES += [
+    'regexp-ast.cc',
+    'regexp-bytecode-generator.cc',
+    'regexp-bytecode-peephole.cc',
+    'regexp-bytecodes.cc',
+    'regexp-compiler-tonode.cc',
+    'regexp-compiler.cc',
+    'regexp-dotprinter.cc',
+    'regexp-interpreter.cc',
+    'regexp-macro-assembler-tracer.cc',
+    'regexp-macro-assembler.cc',
+    'regexp-parser.cc',
+    'regexp-stack.cc',
+]
+
+if CONFIG['ENABLE_INTL_API']:
+    CXXFLAGS += ['-DV8_INTL_SUPPORT']
+    SOURCES += ['property-sequences.cc']
\ No newline at end of file