Revision: 8634
Author: [email protected]
Date: Wed Jul 13 06:16:00 2011
Log: Fix bug in prototype transitions cache clearing introduced by
r8165.
Invalid loop nesting causes full cleanup of the prototype transitions cache
on every GC.
[email protected]
Review URL: http://codereview.chromium.org/7354020
http://code.google.com/p/v8/source/detail?r=8634
Modified:
/branches/bleeding_edge/src/mark-compact.cc
=======================================
--- /branches/bleeding_edge/src/mark-compact.cc Wed Jul 13 02:09:04 2011
+++ /branches/bleeding_edge/src/mark-compact.cc Wed Jul 13 06:16:00 2011
@@ -1661,31 +1661,33 @@
// Clear dead prototype transitions.
int number_of_transitions = map->NumberOfProtoTransitions();
- FixedArray* prototype_transitions =
map->unchecked_prototype_transitions();
- int new_number_of_transitions = 0;
- const int header = Map::kProtoTransitionHeaderSize;
- const int proto_offset =
- header + Map::kProtoTransitionPrototypeOffset;
- const int map_offset = header + Map::kProtoTransitionMapOffset;
- const int step = Map::kProtoTransitionElementsPerEntry;
- for (int i = 0; i < number_of_transitions; i++) {
- Object* prototype = prototype_transitions->get(proto_offset + i *
step);
- Object* cached_map = prototype_transitions->get(map_offset + i *
step);
- if (HeapObject::cast(prototype)->IsMarked() &&
- HeapObject::cast(cached_map)->IsMarked()) {
- if (new_number_of_transitions != i) {
- prototype_transitions->set_unchecked(
- heap_,
- proto_offset + new_number_of_transitions * step,
- prototype,
- UPDATE_WRITE_BARRIER);
- prototype_transitions->set_unchecked(
- heap_,
- map_offset + new_number_of_transitions * step,
- cached_map,
- SKIP_WRITE_BARRIER);
- }
- new_number_of_transitions++;
+ if (number_of_transitions > 0) {
+ FixedArray* prototype_transitions =
map->unchecked_prototype_transitions();
+ int new_number_of_transitions = 0;
+ const int header = Map::kProtoTransitionHeaderSize;
+ const int proto_offset =
+ header + Map::kProtoTransitionPrototypeOffset;
+ const int map_offset = header + Map::kProtoTransitionMapOffset;
+ const int step = Map::kProtoTransitionElementsPerEntry;
+ for (int i = 0; i < number_of_transitions; i++) {
+ Object* prototype = prototype_transitions->get(proto_offset + i *
step);
+ Object* cached_map = prototype_transitions->get(map_offset + i *
step);
+ if (HeapObject::cast(prototype)->IsMarked() &&
+ HeapObject::cast(cached_map)->IsMarked()) {
+ if (new_number_of_transitions != i) {
+ prototype_transitions->set_unchecked(
+ heap_,
+ proto_offset + new_number_of_transitions * step,
+ prototype,
+ UPDATE_WRITE_BARRIER);
+ prototype_transitions->set_unchecked(
+ heap_,
+ map_offset + new_number_of_transitions * step,
+ cached_map,
+ SKIP_WRITE_BARRIER);
+ }
+ new_number_of_transitions++;
+ }
}
// Fill slots that became free with undefined value.
--
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