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[heap] Clear recorded slots for trimmed strings and preparse data

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Currently string and preparse data trimming code creates filler object
without clearing the slots in the trimmed area. This currently works
because the slots are overwritten by filler/free space map.

This CL explicitly clears the slots and makes the code more robust.

Bug: v8:9454
Change-Id: I20ad8a210eb17932e46be5df4b42389955b5e5eb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1778023
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63481}
This commit is contained in:
Ulan Degenbaev 2019-08-30 12:47:33 +02:00 committed by Commit Bot
parent baed90dcbd
commit 1884223839
2 changed files with 10 additions and 4 deletions
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2
src/objects/shared-function-info-inl.h
View File

@ -627,7 +627,7 @@ void SharedFunctionInfo::ClearPreparseData() {
data.address() + UncompiledDataWithoutPreparseData::kSize,
UncompiledDataWithPreparseData::kSize -
UncompiledDataWithoutPreparseData::kSize,
ClearRecordedSlots::kNo);
ClearRecordedSlots::kYes);
// Ensure that the clear was successful.
DCHECK(HasUncompiledDataWithoutPreparseData());

12
src/objects/string.cc
View File

@ -110,6 +110,8 @@ void String::MakeThin(Isolate* isolate, String internalized) {
}
}
bool has_pointers = StringShape(*this).IsIndirect();
int old_size = this->Size();
isolate->heap()->NotifyObjectLayoutChange(*this, old_size, no_gc);
bool one_byte = internalized.IsOneByteRepresentation();
@ -123,7 +125,9 @@ void String::MakeThin(Isolate* isolate, String internalized) {
int size_delta = old_size - ThinString::kSize;
if (size_delta != 0) {
Heap* heap = isolate->heap();
heap->CreateFillerObjectAt(thin_end, size_delta, ClearRecordedSlots::kNo);
heap->CreateFillerObjectAt(
thin_end, size_delta,
has_pointers ? ClearRecordedSlots::kYes : ClearRecordedSlots::kNo);
}
}
@ -178,7 +182,8 @@ bool String::MakeExternal(v8::String::ExternalStringResource* resource) {
// Byte size of the external String object.
int new_size = this->SizeFromMap(new_map);
isolate->heap()->CreateFillerObjectAt(
this->address() + new_size, size - new_size, ClearRecordedSlots::kNo);
this->address() + new_size, size - new_size,
has_pointers ? ClearRecordedSlots::kYes : ClearRecordedSlots::kNo);
if (has_pointers) {
isolate->heap()->ClearRecordedSlotRange(this->address(),
this->address() + new_size);
@ -250,7 +255,8 @@ bool String::MakeExternal(v8::String::ExternalOneByteStringResource* resource) {
// Byte size of the external String object.
int new_size = this->SizeFromMap(new_map);
isolate->heap()->CreateFillerObjectAt(
this->address() + new_size, size - new_size, ClearRecordedSlots::kNo);
this->address() + new_size, size - new_size,
has_pointers ? ClearRecordedSlots::kYes : ClearRecordedSlots::kNo);
if (has_pointers) {
isolate->heap()->ClearRecordedSlotRange(this->address(),
this->address() + new_size);