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Unified Diff: src/transitions.cc

Issue 1163073002: Replace ad-hoc weakness in prototype transitions with WeakCell. (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: Fix crash Created 5 years, 6 months ago
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Index: src/transitions.cc
diff --git a/src/transitions.cc b/src/transitions.cc
index 63bb7fa68f515db5bb90e64fc4629e1807c6b898..c39534bbb566a2930934d2a56482517a2d18e1c6 100644
--- a/src/transitions.cc
+++ b/src/transitions.cc
@@ -233,17 +233,19 @@ bool TransitionArray::CanHaveMoreTransitions(Handle<Map> map) {
// static
-Handle<Map> TransitionArray::PutPrototypeTransition(Handle<Map> map,
- Handle<Object> prototype,
- Handle<Map> target_map) {
+void 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 map;
- if (map->is_dictionary_map() || !FLAG_cache_prototype_transitions) return map;
+ if (map->is_prototype_map()) return;
+ if (map->is_dictionary_map() || !FLAG_cache_prototype_transitions) return;
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;
@@ -251,7 +253,7 @@ Handle<Map> 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 map;
+ if (new_capacity == capacity) return;
cache = FixedArray::CopySize(cache, header + new_capacity);
if (capacity < 0) {
@@ -267,10 +269,8 @@ Handle<Map> TransitionArray::PutPrototypeTransition(Handle<Map> map,
int last = NumberOfPrototypeTransitions(*cache);
int entry = header + last;
- cache->set(entry, *target_map);
+ cache->set(entry, *target_cell);
SetNumberOfPrototypeTransitions(*cache, last + 1);
-
- return map;
}
@@ -281,8 +281,12 @@ 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++) {
- Map* target = Map::cast(cache->get(kProtoTransitionHeaderSize + i));
- if (target->prototype() == *prototype) return handle(target);
+ 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()));
+ }
}
return Handle<Map>();
}
@@ -436,8 +440,9 @@ void TransitionArray::TraverseTransitionTreeInternal(Map* map,
FixedArray* proto_trans = transitions->GetPrototypeTransitions();
for (int i = 0; i < NumberOfPrototypeTransitions(proto_trans); ++i) {
int index = TransitionArray::kProtoTransitionHeaderSize + i;
- TraverseTransitionTreeInternal(Map::cast(proto_trans->get(index)),
- callback, data);
+ WeakCell* cell = WeakCell::cast(proto_trans->get(index));
+ TraverseTransitionTreeInternal(Map::cast(cell->value()), callback,
+ data);
}
}
for (int i = 0; i < transitions->number_of_transitions(); ++i) {
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