From 32d670d8dc147c4db6cd48a67892e2829dff4789 Mon Sep 17 00:00:00 2001
From: ownedbywuigi <ownedbywuigi@gmail.com>
Date: Sat, 28 Mar 2026 10:11:23 +0000
Subject: [PATCH] Revert back to old tuning for reduced startup compile
 pressure

---
 js/src/jit/IonOptimizationLevels.cpp | 26 +++++++++++++-------------
 js/src/jit/JitOptions.cpp            |  6 +++---
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/js/src/jit/IonOptimizationLevels.cpp b/js/src/jit/IonOptimizationLevels.cpp
index 41aa0f6ed9..4f2ae07788 100644
--- a/js/src/jit/IonOptimizationLevels.cpp
+++ b/js/src/jit/IonOptimizationLevels.cpp
@@ -47,11 +47,12 @@ OptimizationInfo::initNormalOptimizationInfo()
     scalarReplacement_ = true;
     smallFunctionMaxInlineDepth_ = 10;
     compilerWarmUpThreshold_ = CompilerWarmupThreshold;
-    // Start compiling tiny helper functions sooner. This is particularly
-    // useful for jQuery-style code with many frequently-called short helpers.
-    compilerSmallFunctionWarmUpThreshold_ = 32;
-    // Inline callees a bit earlier once a script becomes warm.
-    inliningWarmUpThresholdFactor_ = 0.08;
+    // Compile small helper functions somewhat sooner, but keep this conservative
+    // to avoid startup regressions on large script-heavy applications.
+    compilerSmallFunctionWarmUpThreshold_ = 36;
+    // Keep inlining warm-up close to default to avoid excessive early
+    // compilation work during page startup.
+    inliningWarmUpThresholdFactor_ = 0.10;
     inliningRecompileThresholdFactor_ = 4;
 }
 
@@ -115,14 +116,13 @@ OptimizationInfo::compilerWarmUpThreshold(JSScript* script, jsbytecode* pc) cons
         warmUpThreshold *= ratio;
     }
 
-    // jQuery spends a lot of time in medium-small wrappers that are too large
-    // to be classified as "small" but still hot enough to benefit from Ion.
-    // Nudge these scripts toward earlier compilation without affecting large
-    // scripts that are expensive to optimize.
-    if (script->length() <= 400 && numLocalsAndArgs <= 48) {
-        warmUpThreshold = (warmUpThreshold * 3) / 4;
-        if (warmUpThreshold < 30)
-            warmUpThreshold = 30;
+    // Medium-small helper scripts can benefit from earlier Ion entry, but only
+    // when considering loop-entry OSR. Applying this at function entry can hurt
+    // large app startup latency (for example, video sites with many wrappers).
+    if (pc && script->length() <= 400 && numLocalsAndArgs <= 48) {
+        warmUpThreshold = (warmUpThreshold * 4) / 5;
+        if (warmUpThreshold < 40)
+            warmUpThreshold = 40;
     }
 
     if (!pc || JitOptions.eagerCompilation)
diff --git a/js/src/jit/JitOptions.cpp b/js/src/jit/JitOptions.cpp
index d7dacb89a0..2e799740b7 100644
--- a/js/src/jit/JitOptions.cpp
+++ b/js/src/jit/JitOptions.cpp
@@ -167,9 +167,9 @@ DefaultJitOptions::DefaultJitOptions()
     // invalidating the script.
     SET_DEFAULT(osrPcMismatchesBeforeRecompile, 6000);
 
-    // The bytecode length limit for small function. jQuery has many helpers
-    // just above 200 bytecodes, so raise this to compile them sooner.
-    SET_DEFAULT(smallFunctionMaxBytecodeLength_, 320);
+    // The bytecode length limit for small function. Keep this modest to avoid
+    // startup regressions from classifying too many wrapper functions as small.
+    SET_DEFAULT(smallFunctionMaxBytecodeLength_, 256);
 
     // An artificial testing limit for the maximum supported offset of
     // pc-relative jump and call instructions.