Use the incremental root marking visitor for overapproximating the weak closure

Use the incremental root marking visitor for overapproximating the weak closure

Since incremental marking hasn't completed yet at this point, we can't
use the MC's root visitor.

Also, we shouldn't hurry with incremental marking while
overapproximating

BUG=v8:3862
R=hpayer@chromium.org
LOG=n

Committed: https://crrev.com/31f6142a7f2a54a1091a6ff1f21f09e004097cfb
Cr-Commit-Position: refs/heads/master@{#27184}

[Hannes Payer (out of office), 2015-03-12 12:28:48]

Good catch! One nit. LGTM

https://codereview.chromium.org/997423002/diff/1/src/heap/mark-compact.cc
File src/heap/mark-compact.cc (right):

https://codereview.chromium.org/997423002/diff/1/src/heap/mark-compact.cc#new...
src/heap/mark-compact.cc:2232:
heap()->incremental_marking()->CreateRootMarkingVisitor();
Instead of allocating the incremental root marking visitor and deallocating it
later (and leaking it to a different context), why don't you create a method in
incremental marking that incrementally marks the object groups with a stack
allocated visitor?

Hmm, wait, it feels like this method should be part of incremental marking. Can
we move it there?

[jochen (gone - plz use gerrit), 2015-03-12 13:19:47]

something like this?

[Hannes Payer (out of office), 2015-03-12 13:35:05]

You could also move OverApproximateWeakClosure to incremental marking since it
is code only executed when marking incrementally.

[jochen (gone - plz use gerrit), 2015-03-12 15:35:43]

ptal

[jochen (gone - plz use gerrit), 2015-03-13 09:59:27]

https://codereview.chromium.org/997423002/diff/40001/src/heap/incremental-mar...
File src/heap/incremental-marking.cc (right):

https://codereview.chromium.org/997423002/diff/40001/src/heap/incremental-mar...
src/heap/incremental-marking.cc:569:
heap_->mark_compact_collector()->MarkImplicitRefGroups();
this might be wrong too, as it just marks the objects. Guess it should just mark
white objects grey and push them...

[jochen (gone - plz use gerrit), 2015-03-13 13:04:45]

ptal

[Hannes Payer (out of office), 2015-03-13 14:48:21]

Cool. LGTM

[jochen (gone - plz use gerrit), 2015-03-13 14:50:15]

The CQ bit was checked by jochen@chromium.org

[commit-bot: I haz the power, 2015-03-13 14:50:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/997423002/60001

[commit-bot: I haz the power, 2015-03-13 14:51:29]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-03-13 14:51:46]

Patchset 4 (id:??) landed as
https://crrev.com/31f6142a7f2a54a1091a6ff1f21f09e004097cfb
Cr-Commit-Position: refs/heads/master@{#27184}