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Unified Diff: src/heap/heap-inl.h

Issue 1640563004: Reland of "[heap] Parallel newspace evacuation, semispace copy, and compaction \o/" (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: Convert bogus DCHECK into proper branch Created 4 years, 11 months ago
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Index: src/heap/heap-inl.h
diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index a723b3bdae783ea2785fb05a80b7ad2d180652af..5c5a2bace672914e7b31c5ac7d07018d38539bdc 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -467,7 +467,7 @@ void Heap::MoveBlock(Address dst, Address src, int byte_size) {
}
}
-
+template <Heap::FindMementoMode mode>
AllocationMemento* Heap::FindAllocationMemento(HeapObject* object) {
// Check if there is potentially a memento behind the object. If
// the last word of the memento is on another page we return
@@ -476,34 +476,43 @@ AllocationMemento* Heap::FindAllocationMemento(HeapObject* object) {
Address memento_address = object_address + object->Size();
Address last_memento_word_address = memento_address + kPointerSize;
if (!NewSpacePage::OnSamePage(object_address, last_memento_word_address)) {
- return NULL;
+ return nullptr;
}
-
HeapObject* candidate = HeapObject::FromAddress(memento_address);
Map* candidate_map = candidate->map();
// This fast check may peek at an uninitialized word. However, the slow check
// below (memento_address == top) ensures that this is safe. Mark the word as
// initialized to silence MemorySanitizer warnings.
MSAN_MEMORY_IS_INITIALIZED(&candidate_map, sizeof(candidate_map));
- if (candidate_map != allocation_memento_map()) return NULL;
-
- // Either the object is the last object in the new space, or there is another
- // object of at least word size (the header map word) following it, so
- // suffices to compare ptr and top here. Note that technically we do not have
- // to compare with the current top pointer of the from space page during GC,
- // since we always install filler objects above the top pointer of a from
- // space page when performing a garbage collection. However, always performing
- // the test makes it possible to have a single, unified version of
- // FindAllocationMemento that is used both by the GC and the mutator.
- Address top = NewSpaceTop();
- DCHECK(memento_address == top ||
- memento_address + HeapObject::kHeaderSize <= top ||
- !NewSpacePage::OnSamePage(memento_address, top - 1));
- if (memento_address == top) return NULL;
-
- AllocationMemento* memento = AllocationMemento::cast(candidate);
- if (!memento->IsValid()) return NULL;
- return memento;
+ if (candidate_map != allocation_memento_map()) {
+ return nullptr;
+ }
+ AllocationMemento* memento_candidate = AllocationMemento::cast(candidate);
+
+ // Depending on what the memento is used for, we might need to perform
+ // additional checks.
+ Address top;
+ switch (mode) {
+ case Heap::kForGC:
+ return memento_candidate;
+ case Heap::kForRuntime:
+ if (memento_candidate == nullptr) return nullptr;
+ // Either the object is the last object in the new space, or there is
+ // another object of at least word size (the header map word) following
+ // it, so suffices to compare ptr and top here.
+ top = NewSpaceTop();
+ DCHECK(memento_address == top ||
+ memento_address + HeapObject::kHeaderSize <= top ||
+ !NewSpacePage::OnSamePage(memento_address, top - 1));
+ if ((memento_address != top) && memento_candidate->IsValid()) {
+ return memento_candidate;
+ }
+ return nullptr;
+ default:
+ UNREACHABLE();
+ }
+ UNREACHABLE();
+ return nullptr;
}
@@ -513,24 +522,28 @@ void Heap::UpdateAllocationSite(HeapObject* object,
if (!FLAG_allocation_site_pretenuring ||
!AllocationSite::CanTrack(object->map()->instance_type()))
return;
- AllocationMemento* memento = FindAllocationMemento(object);
- if (memento == nullptr) return;
-
- AllocationSite* key = memento->GetAllocationSite();
- DCHECK(!key->IsZombie());
+ AllocationMemento* memento_candidate = FindAllocationMemento<kForGC>(object);
+ if (memento_candidate == nullptr) return;
if (pretenuring_feedback == global_pretenuring_feedback_) {
+ // Entering global pretenuring feedback is only used in the scavenger, where
+ // we are allowed to actually touch the allocation site.
+ if (!memento_candidate->IsValid()) return;
+ AllocationSite* site = memento_candidate->GetAllocationSite();
+ DCHECK(!site->IsZombie());
// For inserting in the global pretenuring storage we need to first
// increment the memento found count on the allocation site.
- if (key->IncrementMementoFoundCount()) {
- global_pretenuring_feedback_->LookupOrInsert(
- key, static_cast<uint32_t>(bit_cast<uintptr_t>(key)));
+ if (site->IncrementMementoFoundCount()) {
+ global_pretenuring_feedback_->LookupOrInsert(site,
+ ObjectHash(site->address()));
}
} else {
- // Any other pretenuring storage than the global one is used as a cache,
- // where the count is later on merge in the allocation site.
- HashMap::Entry* e = pretenuring_feedback->LookupOrInsert(
- key, static_cast<uint32_t>(bit_cast<uintptr_t>(key)));
+ // Entering cached feedback is used in the parallel case. We are not allowed
+ // to dereference the allocation site and rather have to postpone all checks
+ // till actually merging the data.
+ Address key = memento_candidate->GetAllocationSiteUnchecked();
+ HashMap::Entry* e =
+ pretenuring_feedback->LookupOrInsert(key, ObjectHash(key));
DCHECK(e != nullptr);
(*bit_cast<intptr_t*>(&e->value))++;
}
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