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Remove GC post-processing check from externalizing strings

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This check was probably relevant in the past (when GC was different),
but it is unknown today why it exists. It can cause races in a
concurrent set-up though, as tracking the post-processing state is not
atomic.
Due to possible races and no reason to check whether we are in GC
post-processing phase, this check is removed from
String::SupportsExternalization().

SupportsExternalization() was the only user of the logic.

Drive-by: Remove tracking of GC post-processing state, as
Change-Id: Id0a6dd25a8dc6044504b40f1c754612dedcacf75
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4147612
Auto-Submit: Patrick Thier <pthier@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85167}
This commit is contained in:
pthier 2023-01-09 15:38:21 +01:00 committed by V8 LUCI CQ
parent 499697b157
commit 69df64a75c
3 changed files with 1 additions and 8 deletions
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2
src/heap/heap.cc
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@ -1777,14 +1777,12 @@ bool Heap::CollectGarbage(AllocationSpace space,
{ {
TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_WEAK_GLOBAL_HANDLES); TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_WEAK_GLOBAL_HANDLES);
gc_post_processing_depth_++;
{ {
AllowGarbageCollection allow_gc; AllowGarbageCollection allow_gc;
AllowJavascriptExecution allow_js(isolate()); AllowJavascriptExecution allow_js(isolate());
isolate_->global_handles()->PostGarbageCollectionProcessing( isolate_->global_handles()->PostGarbageCollectionProcessing(
collector, gc_callback_flags); collector, gc_callback_flags);
} }
gc_post_processing_depth_--;
} }
{ {

4
src/heap/heap.h
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@ -661,8 +661,6 @@ class Heap {
return ignore_local_gc_requests_depth_ > 0; return ignore_local_gc_requests_depth_ > 0;
} }
inline bool IsInGCPostProcessing() { return gc_post_processing_depth_ > 0; }
bool IsGCWithStack() const; bool IsGCWithStack() const;
// Performs GC after background allocation failure. // Performs GC after background allocation failure.
@ -2206,8 +2204,6 @@ class Heap {
std::atomic<HeapState> gc_state_{NOT_IN_GC}; std::atomic<HeapState> gc_state_{NOT_IN_GC};
int gc_post_processing_depth_ = 0;
// Returns the amount of external memory registered since last global gc. // Returns the amount of external memory registered since last global gc.
V8_EXPORT_PRIVATE uint64_t AllocatedExternalMemorySinceMarkCompact(); V8_EXPORT_PRIVATE uint64_t AllocatedExternalMemorySinceMarkCompact();

3
src/objects/string.cc
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@ -620,8 +620,7 @@ bool String::SupportsExternalization() {
DCHECK_LE(ExternalString::kUncachedSize, this->Size()); DCHECK_LE(ExternalString::kUncachedSize, this->Size());
#endif #endif
Isolate* isolate = GetIsolateFromWritableObject(*this); return true;
return !isolate->heap()->IsInGCPostProcessing();
} }
const char* String::PrefixForDebugPrint() const { const char* String::PrefixForDebugPrint() const {