[heap] Make SlotSet allocation thread-safe and refactor code.

[heap] Make SlotSet allocation thread-safe and refactor code.

BUG=chromium:694255
Review-Url: https://codereview.chromium.org/2764473002
Cr-Commit-Position: refs/heads/master@{#43943}
Committed: https://chromium.googlesource.com/v8/v8/+/00d3098d70e76ba71afcec9935d6d37f0b49f53a

[Hannes Payer (out of office), 2017-03-20 14:25:44]

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

[ulan, 2017-03-20 14:27:15]

lgtm after comments are addressed.

https://codereview.chromium.org/2764473002/diff/1/src/heap/mark-compact.cc
File src/heap/mark-compact.cc (right):

https://codereview.chromium.org/2764473002/diff/1/src/heap/mark-compact.cc#ne...
src/heap/mark-compact.cc:3487: if (page->slot_set<OLD_TO_NEW>() != nullptr) {
Seems like potential race condition here. Should we first cache the value before
checking for null?

https://codereview.chromium.org/2764473002/diff/1/src/heap/mark-compact.cc#ne...
src/heap/mark-compact.cc:3863: if (page->typed_slot_set<OLD_TO_NEW>()) {
Cache the value before checking here and below?

https://codereview.chromium.org/2764473002/diff/1/src/heap/spaces-inl.h
File src/heap/spaces-inl.h (right):

https://codereview.chromium.org/2764473002/diff/1/src/heap/spaces-inl.h#newco...
src/heap/spaces-inl.h:329: DCHECK_NULL(slot_set_[OLD_TO_OLD].Value());
DCHECK_NULL(slot_set<OLD_TO_OLD>()) here and below.

https://codereview.chromium.org/2764473002/diff/1/src/heap/spaces.cc
File src/heap/spaces.cc (right):

https://codereview.chromium.org/2764473002/diff/1/src/heap/spaces.cc#newcode1118
src/heap/spaces.cc:1118: if (slot_set_[OLD_TO_NEW].Value() != nullptr)
ReleaseSlotSet<OLD_TO_NEW>();
Can we fold the guard into the  ReleaseSlotSet function?

[Hannes Payer (out of office), 2017-03-20 15:07:08]

https://codereview.chromium.org/2764473002/diff/1/src/heap/mark-compact.cc
File src/heap/mark-compact.cc (right):

https://codereview.chromium.org/2764473002/diff/1/src/heap/mark-compact.cc#ne...
src/heap/mark-compact.cc:3487: if (page->slot_set<OLD_TO_NEW>() != nullptr) {
On 2017/03/20 14:27:14, ulan wrote:
> Seems like potential race condition here. Should we first cache the value
before
> checking for null?

This site is safe since we never go from allocated to something else allocated.
However, I changed it to be bullet proof.

https://codereview.chromium.org/2764473002/diff/1/src/heap/mark-compact.cc#ne...
src/heap/mark-compact.cc:3863: if (page->typed_slot_set<OLD_TO_NEW>()) {
On 2017/03/20 14:27:15, ulan wrote:
> Cache the value before checking here and below?

As before, that should be safe. But let's be double safe.

https://codereview.chromium.org/2764473002/diff/1/src/heap/spaces-inl.h
File src/heap/spaces-inl.h (right):

https://codereview.chromium.org/2764473002/diff/1/src/heap/spaces-inl.h#newco...
src/heap/spaces-inl.h:329: DCHECK_NULL(slot_set_[OLD_TO_OLD].Value());
On 2017/03/20 14:27:15, ulan wrote:
> DCHECK_NULL(slot_set<OLD_TO_OLD>()) here and below.

Done.

https://codereview.chromium.org/2764473002/diff/1/src/heap/spaces.cc
File src/heap/spaces.cc (right):

https://codereview.chromium.org/2764473002/diff/1/src/heap/spaces.cc#newcode1118
src/heap/spaces.cc:1118: if (slot_set_[OLD_TO_NEW].Value() != nullptr)
ReleaseSlotSet<OLD_TO_NEW>();
On 2017/03/20 14:27:15, ulan wrote:
> Can we fold the guard into the  ReleaseSlotSet function?

Done.

[Hannes Payer (out of office), 2017-03-20 15:07:38]

The CQ bit was checked by hpayer@chromium.org

[Hannes Payer (out of office), 2017-03-20 15:07:39]

The patchset sent to the CQ was uploaded after l-g-t-m from ulan@chromium.org
Link to the patchset: https://codereview.chromium.org/2764473002/#ps20001
(title: "format")

[commit-bot: I haz the power, 2017-03-20 15:07:43]

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, 2017-03-20 15:32:23]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1490022458677210,
"parent_rev": "198bab4ec075f3996d6129dbe2a96df789fed09f", "commit_rev":
"00d3098d70e76ba71afcec9935d6d37f0b49f53a"}

[commit-bot: I haz the power, 2017-03-20 15:32:28]

Description was changed from

==========
[heap] Make SlotSet allocation thread-safe and refactor code.

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

to

==========
[heap] Make SlotSet allocation thread-safe and refactor code.

BUG=chromium:694255

Review-Url: https://codereview.chromium.org/2764473002
Cr-Commit-Position: refs/heads/master@{#43943}
Committed:
https://chromium.googlesource.com/v8/v8/+/00d3098d70e76ba71afcec9935d6d37f0b4...
==========

[commit-bot: I haz the power, 2017-03-20 15:32:28]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/v8/v8/+/00d3098d70e76ba71afcec9935d6d37f0b4...