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heap: Fix --minor-mc ephemeron processing

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Minor MC does not support processing the specialized remembered set
for ephemeron tables.

Temporarily delegate to the regular write barrier for correctness
until the other barrier is supported.

Bug: v8:12262
Change-Id: Iad74b27f8738237dcc1e146b2df3aa6ed8c9a505
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3195895
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77170}
This commit is contained in:
Michael Lippautz 2021-09-30 15:12:04 +02:00 committed by V8 LUCI CQ
parent 2ae6cda1ee
commit 46088a2838
2 changed files with 15 additions and 5 deletions
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17
src/heap/heap.cc
View File

@ -7087,11 +7087,18 @@ void Heap::GenerationalBarrierSlow(HeapObject object, Address slot,
void Heap::RecordEphemeronKeyWrite(EphemeronHashTable table, Address slot) {
DCHECK(ObjectInYoungGeneration(HeapObjectSlot(slot).ToHeapObject()));
int slot_index = EphemeronHashTable::SlotToIndex(table.address(), slot);
InternalIndex entry = EphemeronHashTable::IndexToEntry(slot_index);
auto it =
ephemeron_remembered_set_.insert({table, std::unordered_set<int>()});
it.first->second.insert(entry.as_int());
if (FLAG_minor_mc) {
// Minor MC lacks support for specialized generational ephemeron barriers.
// The regular write barrier works as well but keeps more memory alive.
MemoryChunk* chunk = MemoryChunk::FromHeapObject(table);
RememberedSet<OLD_TO_NEW>::Insert<AccessMode::NON_ATOMIC>(chunk, slot);
} else {
int slot_index = EphemeronHashTable::SlotToIndex(table.address(), slot);
InternalIndex entry = EphemeronHashTable::IndexToEntry(slot_index);
auto it =
ephemeron_remembered_set_.insert({table, std::unordered_set<int>()});
it.first->second.insert(entry.as_int());
}
}
void Heap::EphemeronKeyWriteBarrierFromCode(Address raw_object,

3
src/heap/mark-compact.cc
View File

@ -4797,6 +4797,9 @@ class MinorMarkCompactCollector::RootMarkingVisitor : public RootVisitor {
};
void MinorMarkCompactCollector::CollectGarbage() {
// Minor MC does not support processing the ephemeron remembered set.
DCHECK(heap()->ephemeron_remembered_set_.empty());
{
TRACE_GC(heap()->tracer(), GCTracer::Scope::MINOR_MC_SWEEPING);
heap()->mark_compact_collector()->sweeper()->EnsureIterabilityCompleted();