From 5dde8c1c4ade389cf94a51741de80b64885a38ec Mon Sep 17 00:00:00 2001
From: win7-7 <win7-7@users.noreply.github.com>
Date: Tue, 30 Dec 2025 02:14:06 +0200
Subject: [PATCH] 1342497 - Baldr: store current frame, not previous frame, in
 wasm::FrameIterator

1342497 - Baldr: store current frame, not previous frame, in wasm::FrameIterator.
---
 js/src/wasm/WasmFrameIterator.cpp | 48 ++++++++++++++-----------------
 js/src/wasm/WasmFrameIterator.h   |  1 -
 2 files changed, 21 insertions(+), 28 deletions(-)

diff --git a/js/src/wasm/WasmFrameIterator.cpp b/js/src/wasm/WasmFrameIterator.cpp
index 2da5d69a24..f6ca11fa85 100644
--- a/js/src/wasm/WasmFrameIterator.cpp
+++ b/js/src/wasm/WasmFrameIterator.cpp
@@ -57,7 +57,6 @@ FrameIterator::FrameIterator()
     callsite_(nullptr),
     codeRange_(nullptr),
     fp_(nullptr),
-    pc_(nullptr),
     unwind_(Unwind::False),
     missingFrameMessage_(false)
 {
@@ -70,7 +69,6 @@ FrameIterator::FrameIterator(WasmActivation* activation, Unwind unwind)
     callsite_(nullptr),
     codeRange_(nullptr),
     fp_(activation->fp()),
-    pc_(nullptr),
     unwind_(unwind),
     missingFrameMessage_(false)
 {
@@ -84,7 +82,6 @@ FrameIterator::FrameIterator(WasmActivation* activation, Unwind unwind)
         MOZ_ASSERT(done());
         return;
     }
-    pc_ = (uint8_t*)pc;
 
     code_ = activation_->compartment()->wasm.lookupCode(pc);
     MOZ_ASSERT(code_);
@@ -111,12 +108,8 @@ FrameIterator::operator++()
 {
     MOZ_ASSERT(!done());
     if (fp_) {
-        DebugOnly<uint8_t*> oldfp = fp_;
-        fp_ += callsite_->stackDepth();
-        MOZ_ASSERT_IF(code_->profilingEnabled(), fp_ == CallerFPFromFP(oldfp));
         settle();
     } else if (codeRange_) {
-        MOZ_ASSERT(codeRange_);
         codeRange_ = nullptr;
         missingFrameMessage_ = true;
     } else {
@@ -128,6 +121,9 @@ FrameIterator::operator++()
 void
 FrameIterator::settle()
 {
+    if (unwind_ == Unwind::True)
+        activation_->unwindFP(fp_);
+
     void* returnAddress = ReturnAddressFromFP(fp_);
 
     code_ = activation_->compartment()->wasm.lookupCode(returnAddress);
@@ -136,30 +132,28 @@ FrameIterator::settle()
     codeRange_ = code_->lookupRange(returnAddress);
     MOZ_ASSERT(codeRange_);
 
-    switch (codeRange_->kind()) {
-      case CodeRange::Function:
-        pc_ = (uint8_t*)returnAddress;
-        callsite_ = code_->lookupCallSite(returnAddress);
-        MOZ_ASSERT(callsite_);
-        break;
-      case CodeRange::Entry:
+    if (codeRange_->kind() == CodeRange::Entry) {
         fp_ = nullptr;
-        pc_ = nullptr;
         code_ = nullptr;
         codeRange_ = nullptr;
+        callsite_ = nullptr;
+
+        if (unwind_ == Unwind::True)
+            activation_->unwindFP(nullptr);
         MOZ_ASSERT(done());
-        break;
-      case CodeRange::ImportJitExit:
-      case CodeRange::ImportInterpExit:
-      case CodeRange::TrapExit:
-      case CodeRange::DebugTrap:
-      case CodeRange::Inline:
-      case CodeRange::FarJumpIsland:
-        MOZ_CRASH("Should not encounter an exit during iteration");
+        return;
     }
 
-    if (unwind_ == Unwind::True)
-        activation_->unwindFP(fp_);
+    MOZ_RELEASE_ASSERT(codeRange_->kind() == CodeRange::Function);
+
+    callsite_ = code_->lookupCallSite(returnAddress);
+    MOZ_ASSERT(callsite_);
+
+    DebugOnly<uint8_t*> oldfp = fp_;
+    fp_ += callsite_->stackDepth();
+    MOZ_ASSERT_IF(code_->profilingEnabled(), fp_ == CallerFPFromFP(oldfp));
+
+    MOZ_ASSERT(!done());
 }
 
 const char*
@@ -225,7 +219,7 @@ Instance*
 FrameIterator::instance() const
 {
     MOZ_ASSERT(!done() && debugEnabled());
-    return TlsDataFromFP(fp_ + callsite_->stackDepth())->instance;
+    return TlsDataFromFP(fp_)->instance;
 }
 
 bool
@@ -243,7 +237,7 @@ FrameIterator::debugFrame() const
 {
     MOZ_ASSERT(!done() && debugEnabled());
     // The fp() points to wasm::Frame.
-    void* buf = static_cast<uint8_t*>(fp_ + callsite_->stackDepth()) - DebugFrame::offsetOfFrame();
+    void* buf = static_cast<uint8_t*>(fp_) - DebugFrame::offsetOfFrame();
     return static_cast<DebugFrame*>(buf);
 }
 
diff --git a/js/src/wasm/WasmFrameIterator.h b/js/src/wasm/WasmFrameIterator.h
index 3e3a5de000..69fccda6b9 100644
--- a/js/src/wasm/WasmFrameIterator.h
+++ b/js/src/wasm/WasmFrameIterator.h
@@ -59,7 +59,6 @@ class FrameIterator
     const CallSite* callsite_;
     const CodeRange* codeRange_;
     uint8_t* fp_;
-    uint8_t* pc_;
     Unwind unwind_;
     bool missingFrameMessage_;