Avoid creating weak cells for literal arrays that are empty of literals.

Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap directly instead of using a WeakCell,
because all data in the feedback vector is already held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=chromium:615831
Committed: https://crrev.com/3cfcc7e111a32f231a483b8feda19ef2d8c45253
Cr-Commit-Position: refs/heads/master@{#36786}

[mvstanton, 2016-06-06 20:48:20]

Description was changed from

==========
Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap with an ordinary Cell instead
of a WeakCell, because all data in the feedback vector is held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=
==========

to

==========
Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap directly instead of using a WeakCell,
because all data in the feedback vector is already held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=chromium:615831
==========

[mvstanton, 2016-06-06 20:48:34]

Description was changed from

==========
Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap directly instead of using a WeakCell,
because all data in the feedback vector is already held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=chromium:615831
==========

to

==========
Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap directly instead of using a WeakCell,
because all data in the feedback vector is already held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=chromium:615831
==========

[mvstanton, 2016-06-06 20:50:02]

mvstanton@chromium.org changed reviewers:
+ mstarzinger@chromium.org

[mvstanton, 2016-06-06 20:50:02]

Hi Michael,
Here are the changes we discussed this morning, thanks for the look!
--Mike

[Michael Starzinger, 2016-06-07 09:41:37]

LGTM. Only looked at the ARM ported, assuming the others are more or less the
same.

https://codereview.chromium.org/2031123003/diff/40001/src/type-feedback-vecto...
File src/type-feedback-vector.cc (right):

https://codereview.chromium.org/2031123003/diff/40001/src/type-feedback-vecto...
src/type-feedback-vector.cc:284: TypeFeedbackVector* vector = NULL;
nit: s/NULL/nullptr/

https://codereview.chromium.org/2031123003/diff/40001/src/type-feedback-vecto...
src/type-feedback-vector.cc:294: if (vector != NULL) {
nit: s/NULL/nullptr/

[mvstanton, 2016-06-07 11:35:07]

The CQ bit was checked by mvstanton@chromium.org

[mvstanton, 2016-06-07 11:35:07]

The patchset sent to the CQ was uploaded after l-g-t-m from
mstarzinger@chromium.org
Link to the patchset: https://codereview.chromium.org/2031123003/#ps80001
(title: "REBASE.")

[commit-bot: I haz the power, 2016-06-07 11:35:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2031123003/80001

[mvstanton, 2016-06-07 11:35:34]

Thanks, addressed!

https://codereview.chromium.org/2031123003/diff/40001/src/type-feedback-vecto...
File src/type-feedback-vector.cc (right):

https://codereview.chromium.org/2031123003/diff/40001/src/type-feedback-vecto...
src/type-feedback-vector.cc:284: TypeFeedbackVector* vector = NULL;
On 2016/06/07 09:41:37, Michael Starzinger wrote:
> nit: s/NULL/nullptr/

Done.

https://codereview.chromium.org/2031123003/diff/40001/src/type-feedback-vecto...
src/type-feedback-vector.cc:294: if (vector != NULL) {
On 2016/06/07 09:41:37, Michael Starzinger wrote:
> nit: s/NULL/nullptr/

Done.

[commit-bot: I haz the power, 2016-06-07 12:01:58]

Description was changed from

==========
Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap directly instead of using a WeakCell,
because all data in the feedback vector is already held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=chromium:615831
==========

to

==========
Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap directly instead of using a WeakCell,
because all data in the feedback vector is already held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=chromium:615831
==========

[commit-bot: I haz the power, 2016-06-07 12:01:59]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2016-06-07 12:04:06]

Description was changed from

==========
Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap directly instead of using a WeakCell,
because all data in the feedback vector is already held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=chromium:615831
==========

to

==========
Avoid creating weak cells for literal arrays that are empty of literals.

It may be that we have a feedback vector, but no literals. In this case
we can store into the OptimizedCodeMap directly instead of using a WeakCell,
because all data in the feedback vector is already held weakly.

The use of a WeakCell in the OptimizedCodeMap is only required when
there are literals which may hold maps strongly.

This is to address a performance regression caused by the creation of
a large number of WeakCells.

BUG=chromium:615831

Committed: https://crrev.com/3cfcc7e111a32f231a483b8feda19ef2d8c45253
Cr-Commit-Position: refs/heads/master@{#36786}
==========

[commit-bot: I haz the power, 2016-06-07 12:04:07]

Patchset 5 (id:??) landed as
https://crrev.com/3cfcc7e111a32f231a483b8feda19ef2d8c45253
Cr-Commit-Position: refs/heads/master@{#36786}