Commit fd2e3344 authored by ulan's avatar ulan Committed by Commit bot

Revert of Replace ad-hoc weakness in prototype transitions with WeakCell....

Revert of Replace ad-hoc weakness in prototype transitions with WeakCell. (patchset #2 id:20001 of https://codereview.chromium.org/1163073002/)

Reason for revert:
GC stress failures.

Original issue's description:
> Replace ad-hoc weakness in prototype transitions with WeakCell.
>
> BUG=
>
> Committed: https://crrev.com/bfb81fbe0d38c88cc1b6ed6eb1a4b8cbe2c469c3
> Cr-Commit-Position: refs/heads/master@{#28830}

TBR=jkummerow@chromium.org,hpayer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1169733002

Cr-Commit-Position: refs/heads/master@{#28832}
parent 29b572d4
......@@ -2404,10 +2404,11 @@ void MarkCompactCollector::ClearNonLivePrototypeTransitions(Map* map) {
const int header = TransitionArray::kProtoTransitionHeaderSize;
int new_number_of_transitions = 0;
for (int i = 0; i < number_of_transitions; i++) {
Object* cell = prototype_transitions->get(header + i);
if (!WeakCell::cast(cell)->cleared()) {
Object* cached_map = prototype_transitions->get(header + i);
if (IsMarked(cached_map)) {
if (new_number_of_transitions != i) {
prototype_transitions->set(header + new_number_of_transitions, cell);
prototype_transitions->set(header + new_number_of_transitions,
cached_map, SKIP_WRITE_BARRIER);
}
new_number_of_transitions++;
}
......
......@@ -571,8 +571,13 @@ void StaticMarkingVisitor<StaticVisitor>::MarkTransitionArray(
if (!StaticVisitor::MarkObjectWithoutPush(heap, transitions)) return;
if (transitions->HasPrototypeTransitions()) {
StaticVisitor::VisitPointer(heap,
transitions->GetPrototypeTransitionsSlot());
// Mark prototype transitions array but do not push it onto marking
// stack, this will make references from it weak. We will clean dead
// prototype transitions in ClearNonLiveReferences.
Object** slot = transitions->GetPrototypeTransitionsSlot();
HeapObject* obj = HeapObject::cast(*slot);
heap->mark_compact_collector()->RecordSlot(slot, slot, obj);
StaticVisitor::MarkObjectWithoutPush(heap, obj);
}
int num_transitions = TransitionArray::NumberOfTransitions(transitions);
......
......@@ -233,19 +233,17 @@ bool TransitionArray::CanHaveMoreTransitions(Handle<Map> map) {
// static
void TransitionArray::PutPrototypeTransition(Handle<Map> map,
Handle<Map> TransitionArray::PutPrototypeTransition(Handle<Map> map,
Handle<Object> prototype,
Handle<Map> target_map) {
DCHECK(HeapObject::cast(*prototype)->map()->IsMap());
// Don't cache prototype transition if this map is either shared, or a map of
// a prototype.
if (map->is_prototype_map()) return;
if (map->is_dictionary_map() || !FLAG_cache_prototype_transitions) return;
if (map->is_prototype_map()) return map;
if (map->is_dictionary_map() || !FLAG_cache_prototype_transitions) return map;
const int header = kProtoTransitionHeaderSize;
Handle<WeakCell> target_cell = Map::WeakCellForMap(target_map);
Handle<FixedArray> cache(GetPrototypeTransitions(*map));
int capacity = cache->length() - header;
int transitions = NumberOfPrototypeTransitions(*cache) + 1;
......@@ -253,7 +251,7 @@ void TransitionArray::PutPrototypeTransition(Handle<Map> map,
if (transitions > capacity) {
// Grow array by factor 2 up to MaxCachedPrototypeTransitions.
int new_capacity = Min(kMaxCachedPrototypeTransitions, transitions * 2);
if (new_capacity == capacity) return;
if (new_capacity == capacity) return map;
cache = FixedArray::CopySize(cache, header + new_capacity);
if (capacity < 0) {
......@@ -269,8 +267,10 @@ void TransitionArray::PutPrototypeTransition(Handle<Map> map,
int last = NumberOfPrototypeTransitions(*cache);
int entry = header + last;
cache->set(entry, *target_cell);
cache->set(entry, *target_map);
SetNumberOfPrototypeTransitions(*cache, last + 1);
return map;
}
......@@ -281,12 +281,8 @@ Handle<Map> TransitionArray::GetPrototypeTransition(Handle<Map> map,
FixedArray* cache = GetPrototypeTransitions(*map);
int number_of_transitions = NumberOfPrototypeTransitions(cache);
for (int i = 0; i < number_of_transitions; i++) {
WeakCell* target_cell =
WeakCell::cast(cache->get(kProtoTransitionHeaderSize + i));
if (!target_cell->cleared() &&
Map::cast(target_cell->value())->prototype() == *prototype) {
return handle(Map::cast(target_cell->value()));
}
Map* target = Map::cast(cache->get(kProtoTransitionHeaderSize + i));
if (target->prototype() == *prototype) return handle(target);
}
return Handle<Map>();
}
......@@ -440,9 +436,8 @@ void TransitionArray::TraverseTransitionTreeInternal(Map* map,
FixedArray* proto_trans = transitions->GetPrototypeTransitions();
for (int i = 0; i < NumberOfPrototypeTransitions(proto_trans); ++i) {
int index = TransitionArray::kProtoTransitionHeaderSize + i;
WeakCell* cell = WeakCell::cast(proto_trans->get(index));
TraverseTransitionTreeInternal(Map::cast(cell->value()), callback,
data);
TraverseTransitionTreeInternal(Map::cast(proto_trans->get(index)),
callback, data);
}
}
for (int i = 0; i < transitions->number_of_transitions(); ++i) {
......
......@@ -92,7 +92,8 @@ class TransitionArray: public FixedArray {
// 0: finger - index of the first free cell in the cache
// 1 + i: target map
static const int kMaxCachedPrototypeTransitions = 256;
static void PutPrototypeTransition(Handle<Map> map, Handle<Object> prototype,
static Handle<Map> PutPrototypeTransition(Handle<Map> map,
Handle<Object> prototype,
Handle<Map> target_map);
static Handle<Map> GetPrototypeTransition(Handle<Map> map,
......
......@@ -2521,8 +2521,7 @@ TEST(PrototypeTransitionClearing) {
TransitionArray::GetPrototypeTransitions(baseObject->map());
for (int i = initialTransitions; i < initialTransitions + transitions; i++) {
int j = TransitionArray::kProtoTransitionHeaderSize + i;
CHECK(trans->get(j)->IsWeakCell());
CHECK(WeakCell::cast(trans->get(j))->value()->IsMap());
CHECK(trans->get(j)->IsMap());
}
// Make sure next prototype is placed on an old-space evacuation candidate.
......
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