Reviewers: sandholm,
Description:
Merge changes 8634 and 8636 to trunk.
Fix bug in prototype transitions cache clearing introduced by r8165.
Invalid loop nesting causes full cleanup of the prototype transitions cache
on
every GC.
Please review this at http://codereview.chromium.org/7342045/
SVN Base: http://v8.googlecode.com/svn/trunk/
Affected files:
M src/mark-compact.cc
Index: src/mark-compact.cc
===================================================================
--- src/mark-compact.cc (revision 8636)
+++ src/mark-compact.cc (working copy)
@@ -1661,31 +1661,34 @@
// 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);
+ 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++;
}
- new_number_of_transitions++;
}
// Fill slots that became free with undefined value.
--
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