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[compiler] Disable concurrent read optimization for Strings

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GetOwnElementFromHeap uses LookupIterator which requires heap
allocation. Therefore, we cannot call it from the background thread
with concurrent access.

Bug: v8:7790, v8:11012
Change-Id: I29733db69a8935c7b7585c776ab1a2d7f1265e95
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2465841
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70488}
This commit is contained in:
Santiago Aboy Solanes 2020-10-13 15:27:49 +01:00 committed by Commit Bot
parent d73c32b9f7
commit 567c3a1cf5
1 changed files with 4 additions and 13 deletions
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17
src/compiler/js-heap-broker.cc
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@ -3813,19 +3813,10 @@ base::Optional<ObjectRef> ObjectRef::GetOwnConstantElement(
uint32_t index, SerializationPolicy policy) const {
if (!(IsJSObject() || IsString())) return base::nullopt;
if (data_->should_access_heap()) {
// TODO(neis): Once the CHECK_NE below is eliminated, i.e. once we can
// safely read from the background thread, the special branch for read-only
// objects can be removed as well.
if (data_->kind() == ObjectDataKind::kUnserializedReadOnlyHeapObject) {
DCHECK(IsString());
// TODO(mythria): For ReadOnly strings, currently we cannot access data
// from heap without creating handles since we use LookupIterator. We
// should have a custom implementation for read only strings that doesn't
// create handles. Till then it is OK to disable this optimization since
// this only impacts keyed accesses on read only strings.
return base::nullopt;
}
CHECK_NE(data_->kind(), ObjectDataKind::kNeverSerializedHeapObject);
// TODO(solanes, neis, v8:7790, v8:11012): Re-enable this optmization for
// concurrent inlining when we have the infrastructure to safely do so.
if (broker()->is_concurrent_inlining() && IsString()) return base::nullopt;
CHECK_EQ(data_->kind(), ObjectDataKind::kUnserializedHeapObject);
return GetOwnElementFromHeap(broker(), object(), index, true);
}
ObjectData* element = nullptr;