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[compiler] Fix a bug in global property access reduction

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Bug: chromium:1247763
Change-Id: I6f09d5113ef7e4774032ea586d5a1ada98aa4b1b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3149462
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76752}
This commit is contained in:
Georg Neis 2021-09-09 14:41:58 +02:00 committed by V8 LUCI CQ
parent 62ed75a1d2
commit 6391d7a58d
1 changed files with 7 additions and 11 deletions
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18
src/compiler/js-native-context-specialization.cc
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@ -804,6 +804,12 @@ Reduction JSNativeContextSpecialization::ReduceGlobalAccess(
return NoChange();
} else if (property_cell_type == PropertyCellType::kUndefined) {
return NoChange();
} else if (property_cell_type == PropertyCellType::kConstantType) {
// We rely on stability further below.
if (property_cell_value.IsHeapObject() &&
!property_cell_value.AsHeapObject().map().is_stable()) {
return NoChange();
}
}
} else if (access_mode == AccessMode::kHas) {
DCHECK_EQ(receiver, lookup_start_object);
@ -922,17 +928,7 @@ Reduction JSNativeContextSpecialization::ReduceGlobalAccess(
if (property_cell_value.IsHeapObject()) {
MapRef property_cell_value_map =
property_cell_value.AsHeapObject().map();
if (property_cell_value_map.is_stable()) {
dependencies()->DependOnStableMap(property_cell_value_map);
} else {
// The value's map is already unstable. If this store were to go
// through the C++ runtime, it would transition the PropertyCell to
// kMutable. We don't want to change the cell type from generated
// code (to simplify concurrent heap access), however, so we keep
// it as kConstantType and do the store anyways (if the new value's
// map matches). This is safe because it merely prolongs the limbo
// state that we are in already.
}
dependencies()->DependOnStableMap(property_cell_value_map);
// Check that the {value} is a HeapObject.
value = effect = graph()->NewNode(simplified()->CheckHeapObject(),