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[heap] Skip ephemeron values that shouldn't be marked

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Bug: chromium:1403129
Change-Id: Ic26583be78e4e16a5bc18d8d8ce2bfb79ec70dad
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4136976
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85270}
This commit is contained in:
Shu-yu Guo 2023-01-12 11:26:42 -08:00 committed by V8 LUCI CQ
parent aae0ec104b
commit c57a13dc3b
2 changed files with 14 additions and 2 deletions
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9
src/heap/mark-compact.cc
View File

@ -2613,6 +2613,15 @@ std::pair<size_t, size_t> MarkCompactCollector::ProcessMarkingWorklist(
}
bool MarkCompactCollector::ProcessEphemeron(HeapObject key, HeapObject value) {
// Objects in the shared heap are prohibited from being used as keys in
// WeakMaps and WeakSets and therefore cannot be ephemeron keys, because that
// would enable thread local -> shared heap edges.
DCHECK(!key.InSharedWritableHeap());
// Usually values that should not be marked are not added to the ephemeron
// worklist. However, minor collection during incremental marking may promote
// strings from the younger generation into the shared heap. This
// ShouldMarkObject call catches those cases.
if (!ShouldMarkObject(value)) return false;
if (marking_state()->IsBlackOrGrey(key)) {
if (marking_state()->WhiteToGrey(value)) {
local_marking_worklists()->Push(value);

7
src/heap/marking-visitor-inl.h
View File

@ -365,8 +365,11 @@ int MarkingVisitorBase<ConcreteVisitor, MarkingState>::VisitEphemeronHashTable(
ObjectSlot value_slot =
table.RawFieldOfElementAt(EphemeronHashTable::EntryToValueIndex(i));
if (!ShouldMarkObject(key) ||
concrete_visitor()->marking_state()->IsBlackOrGrey(key)) {
// Objects in the shared heap are prohibited from being used as keys in
// WeakMaps and WeakSets and therefore cannot be ephemeron keys. See also
// MarkCompactCollector::ProcessEphemeron.
DCHECK(!key.InSharedWritableHeap());
if (concrete_visitor()->marking_state()->IsBlackOrGrey(key)) {
VisitPointer(table, value_slot);
} else {
Object value_obj = table.ValueAt(i);