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When reading the map from a live object, use a barrier load

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It could happen that we shrink a live object on the main thread (e.g.
MigrateFastToSlow) while we're sweeping the same page. The main
thread first creates a filler object that the release-stores the new
map. Therefore it's important to barrier load the map word of live
objects from the sweeper thread.

BUG=none
R=ulan@chromium.org,hpayer@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/797623002

Cr-Commit-Position: refs/heads/master@{#25780}
This commit is contained in:
jochen 2014-12-11 07:25:23 -08:00 committed by Commit bot
parent d0cad384b2
commit b7caca9f9a
1 changed files with 1 additions and 1 deletions
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2
src/heap/mark-compact.cc
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@ -3243,7 +3243,7 @@ static int Sweep(PagedSpace* space, FreeList* free_list, Page* p,
}
HeapObject* live_object = HeapObject::FromAddress(free_end);
DCHECK(Marking::IsBlack(Marking::MarkBitFrom(live_object)));
Map* map = live_object->map();
Map* map = live_object->synchronized_map();
int size = live_object->SizeFromMap(map);
if (sweeping_mode == SWEEP_AND_VISIT_LIVE_OBJECTS) {
live_object->IterateBody(map->instance_type(), size, v);