Prevent excessive processing of weak maps while marking.

Prevent excessive processing of weak maps while marking.

This makes sure processing of Harmony weak maps is only triggerd twice
during a mark-compact collection. Note that the processing itself still
is a fix-point iteration with quadratic worst-case time.

R=hpayer@chromium.org
BUG=v8:2699
Committed: http://code.google.com/p/v8/source/detail?r=14940

[Hannes Payer (out of office), 2013-06-04 16:29:58]

LGTM! one renaming nit.

https://codereview.chromium.org/16286018/diff/1/src/mark-compact.h
File src/mark-compact.h (right):

https://codereview.chromium.org/16286018/diff/1/src/mark-compact.h#newcode854
src/mark-compact.h:854: void ProcessAtomicMarking(RootMarkingVisitor* visitor);
The function name may be confusing if we add concurrency to the marker. Can we
rename this method to something like ProccessWeakReferences()?

[Michael Starzinger, 2013-06-04 16:42:41]

https://codereview.chromium.org/16286018/diff/1/src/mark-compact.h
File src/mark-compact.h (right):

https://codereview.chromium.org/16286018/diff/1/src/mark-compact.h#newcode854
src/mark-compact.h:854: void ProcessAtomicMarking(RootMarkingVisitor* visitor);
On 2013/06/04 16:29:58, Hannes Payer wrote:
> The function name may be confusing if we add concurrency to the marker. Can we
> rename this method to something like ProccessWeakReferences()?

Yep, I am not happy with the "atomic" in the name either. But also "weak" has a
different meaning internally. How about ProcessEphemerons()?

[Michael Starzinger, 2013-06-04 17:16:08]

Addressed comments. Landing.

https://codereview.chromium.org/16286018/diff/1/src/mark-compact.h
File src/mark-compact.h (right):

https://codereview.chromium.org/16286018/diff/1/src/mark-compact.h#newcode854
src/mark-compact.h:854: void ProcessAtomicMarking(RootMarkingVisitor* visitor);
On 2013/06/04 16:42:41, Michael Starzinger wrote:
> On 2013/06/04 16:29:58, Hannes Payer wrote:
> > The function name may be confusing if we add concurrency to the marker. Can
we
> > rename this method to something like ProccessWeakReferences()?
> 
> Yep, I am not happy with the "atomic" in the name either. But also "weak" has
a
> different meaning internally. How about ProcessEphemerons()?

Done, as discussed offline.

[Michael Starzinger, 2013-06-04 17:20:19]

Committed patchset #2 manually as r14940 (presubmit successful).