[compiler] Put reuse_scope_infos behind a disabled flag

verwaest · V8 LUCI CQ · commit 9e36f73b962d · 2024-07-12T17:39:42.000Z
Bug: 352673356 Change-Id: Ief4db2f6520b17a9098d9d7a80cd22e87be297b9 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5703896 Reviewed-by: Jakob Kummerow <jkummerow@chromium.org> Auto-Submit: Toon Verwaest <verwaest@chromium.org> Commit-Queue: Toon Verwaest <verwaest@chromium.org> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org> Cr-Commit-Position: refs/heads/main@{#95007}
diff --git a/src/ast/scopes.cc b/src/ast/scopes.cc
@@ -2716,7 +2716,9 @@ void Scope::AllocateScopeInfosRecursively(
 #ifdef DEBUG
     // Mark this ID as being used. Skip hidden scopes because they are
     // synthetic, unreusable, but hard to make unique.
-    if (!is_hidden()) scope_infos_to_reuse[UniqueIdInScript()] = {};
+    if (v8_flags.reuse_scope_infos && !is_hidden()) {
+      scope_infos_to_reuse[UniqueIdInScript()] = {};
+    }
 #endif
     scope_info_ = ScopeInfo::Create(isolate, zone(), this, outer_scope);
     DCHECK_EQ(UniqueIdInScript(), scope_info_->UniqueIdInScript());
@@ -2810,7 +2812,7 @@ void DeclarationScope::AllocateScopeInfos(ParseInfo* info,
 
   Tagged<WeakFixedArray> infos = script->shared_function_infos();
   std::unordered_map<int, Handle<ScopeInfo>> scope_infos_to_reuse;
-  if (infos->length() != 0) {
+  if (v8_flags.reuse_scope_infos && infos->length() != 0) {
     // Look at all the existing inner functions (they are numbered id+1 until
     // max_id+1) to reattach their outer scope infos to corresponding scopes.
     for (int i = info->literal()->function_literal_id() + 1;
diff --git a/src/codegen/compiler.cc b/src/codegen/compiler.cc
@@ -2017,6 +2017,7 @@ class ConstantPoolPointerForwarder {
   }
 
   void RecordOuterScopeInfos(Tagged<MaybeObject> maybe_old_sfi) {
+    if (!v8_flags.reuse_scope_infos) return;
     Tagged<SharedFunctionInfo> old_sfi =
         Cast<SharedFunctionInfo>(maybe_old_sfi.GetHeapObjectAssumeWeak());
     if (!old_sfi->HasOuterScopeInfo()) return;
diff --git a/src/flags/flag-definitions.h b/src/flags/flag-definitions.h
@@ -989,6 +989,9 @@ DEFINE_BOOL(trace_track_allocation_sites, false,
 DEFINE_BOOL(trace_migration, false, "trace object migration")
 DEFINE_BOOL(trace_generalization, false, "trace map generalization")
 
+DEFINE_BOOL(reuse_scope_infos, false,
+            "reuse scope infos from previous compiles")
+
 // Flags for Sparkplug
 #undef FLAG
 #if V8_ENABLE_SPARKPLUG

Original file line number	Diff line number	Diff line change
`@@ -2017,6 +2017,7 @@ class ConstantPoolPointerForwarder {`
`2017`	`2017`	`}`
`2018`	`2018`
`2019`	`2019`	`void RecordOuterScopeInfos(Tagged<MaybeObject> maybe_old_sfi) {`
	`2020`	`+ if (!v8_flags.reuse_scope_infos) return;`
`2020`	`2021`	`Tagged<SharedFunctionInfo> old_sfi =`
`2021`	`2022`	`Cast<SharedFunctionInfo>(maybe_old_sfi.GetHeapObjectAssumeWeak());`
`2022`	`2023`	`if (!old_sfi->HasOuterScopeInfo()) return;`