[heap] Make object field write atomic if concurrent marking is enabled.

[heap] Make object field write atomic if concurrent marking is enabled.

This patch also makes concurrent marking visitor loads atomic.

BUG=chromium:694255
Review-Url: https://codereview.chromium.org/2872443003
Cr-Commit-Position: refs/heads/master@{#45179}
Committed: https://chromium.googlesource.com/v8/v8/+/78082436025c1016aaf355251a0e4531487eaf87

[ulan, 2017-05-08 11:07:06]

ulan@chromium.org changed reviewers:
+ mlippautz@chromium.org

[ulan, 2017-05-08 11:07:07]

ptal

[Michael Lippautz, 2017-05-08 20:01:33]

lgtm

[Hannes Payer (out of office), 2017-05-08 20:08:02]

hpayer@chromium.org changed reviewers:
+ hpayer@chromium.org

[Hannes Payer (out of office), 2017-05-08 20:08:02]

lgtm

[ulan, 2017-05-09 09:08:45]

The CQ bit was checked by ulan@chromium.org

[commit-bot: I haz the power, 2017-05-09 09:08:49]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-09 09:42:50]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1494320925954180, "parent_rev":
"4fa473cb75d8e8a307181048e387cd398ea2bbcf", "commit_rev":
"78082436025c1016aaf355251a0e4531487eaf87"}

[commit-bot: I haz the power, 2017-05-09 09:42:57]

Description was changed from

==========
[heap] Make object field write atomic if concurrent marking is enabled.

This patch also makes concurrent marking visitor loads atomic.

BUG=chromium:694255
==========

to

==========
[heap] Make object field write atomic if concurrent marking is enabled.

This patch also makes concurrent marking visitor loads atomic.

BUG=chromium:694255

Review-Url: https://codereview.chromium.org/2872443003
Cr-Commit-Position: refs/heads/master@{#45179}
Committed:
https://chromium.googlesource.com/v8/v8/+/78082436025c1016aaf355251a0e4531487...
==========

[commit-bot: I haz the power, 2017-05-09 09:42:58]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/78082436025c1016aaf355251a0e4531487...