[turbofan] Also push Return into Merge even if there's no EffectPhi.

[turbofan] Also push Return into Merge even if there's no EffectPhi.

We already had an optimization in the CommonOperatorReducer that would
duplicate a Return with Phi, EffectPhi and Merge inputs into the
respective branches. But we can also do the same if the effect input of
the Return dominates all branches, i.e. if the Return and Phi nodes are
the only users of the Merge node.

This helps with the awkward code generation that we currently observe
for || and && in return position.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2668903002
Cr-Commit-Position: refs/heads/master@{#42839}
Committed: https://chromium.googlesource.com/v8/v8/+/44cac16f48f0f2fe8692e4b4410598640a1a2a26

[Benedikt Meurer, 2017-02-01 06:13:15]

The CQ bit was checked by bmeurer@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-02-01 06:13:26]

Dry run: 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, 2017-02-01 06:39:20]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-01 06:39:21]

Dry run: This issue passed the CQ dry run.

[Jarin, 2017-02-01 08:00:01]

lgtm

[Jarin, 2017-02-01 08:11:48]

lgtm

[Benedikt Meurer, 2017-02-01 08:31:37]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2017-02-01 08:31:38]

The patchset sent to the CQ was uploaded after l-g-t-m from jarin@chromium.org
Link to the patchset: https://codereview.chromium.org/2668903002/#ps20001
(title: "REBASE")

[Benedikt Meurer, 2017-02-01 08:31:41]

The CQ bit was unchecked by bmeurer@chromium.org

[Benedikt Meurer, 2017-02-01 08:32:09]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2017-02-01 08:32:09]

The patchset sent to the CQ was uploaded after l-g-t-m from jarin@chromium.org
Link to the patchset: https://codereview.chromium.org/2668903002/#ps40001
(title: "REBASE")

[commit-bot: I haz the power, 2017-02-01 08:32:12]

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, 2017-02-01 08:59:28]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1485937929368900,
"parent_rev": "d52ec9e6cfb0c5ad81d614b11957cb85fba06d96", "commit_rev":
"44cac16f48f0f2fe8692e4b4410598640a1a2a26"}

[commit-bot: I haz the power, 2017-02-01 08:59:33]

Description was changed from

==========
[turbofan] Also push Return into Merge even if there's no EffectPhi.

We already had an optimization in the CommonOperatorReducer that would
duplicate a Return with Phi, EffectPhi and Merge inputs into the
respective branches. But we can also do the same if the effect input of
the Return dominates all branches, i.e. if the Return and Phi nodes are
the only users of the Merge node.

This helps with the awkward code generation that we currently observe
for || and && in return position.

R=jarin@chromium.org
==========

to

==========
[turbofan] Also push Return into Merge even if there's no EffectPhi.

We already had an optimization in the CommonOperatorReducer that would
duplicate a Return with Phi, EffectPhi and Merge inputs into the
respective branches. But we can also do the same if the effect input of
the Return dominates all branches, i.e. if the Return and Phi nodes are
the only users of the Merge node.

This helps with the awkward code generation that we currently observe
for || and && in return position.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2668903002
Cr-Commit-Position: refs/heads/master@{#42839}
Committed:
https://chromium.googlesource.com/v8/v8/+/44cac16f48f0f2fe8692e4b4410598640a1...
==========

[commit-bot: I haz the power, 2017-02-01 08:59:34]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/v8/v8/+/44cac16f48f0f2fe8692e4b4410598640a1...