[turbofan] Consolidate compatible element loads.

[turbofan] Consolidate compatible element loads.

This changes behavior of TurboFan to match the behavior of Crankshaft
when it comes to polymorphic loads of similar elements kind (i.e. all
tagged or all double), where we should use the "worst case" code without
a transition. This is often much faster than transitioning the elements
to the worst case first, trading a TransitionElementsKind for a CheckMaps
and avoiding mutation of the array.

This is beneficial for various crypto benchmarks, which don't need to
pay the cost for TransitionElementsKind now.

R=jarin@chromium.org
BUG=v8:5267
Review-Url: https://codereview.chromium.org/2836943003
Cr-Commit-Position: refs/heads/master@{#44815}
Committed: https://chromium.googlesource.com/v8/v8/+/d853b2382e035ef6e4b38ebbc8de827570d076b2

[Benedikt Meurer, 2017-04-24 18:48:43]

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

[commit-bot: I haz the power, 2017-04-24 18:48:52]

Dry run: CQ is trying da patch.

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

[Jarin, 2017-04-24 19:06:18]

lgtm.

Could you say here where and by how much it actually helps?

[Benedikt Meurer, 2017-04-24 19:07:35]

I see 2-3% on the SunSpider/crypto line items and 5% on the Octane/crypto one
locally. Waiting for the try perf bots to finish.

[commit-bot: I haz the power, 2017-04-24 19:15:16]

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

[commit-bot: I haz the power, 2017-04-24 19:15:17]

Dry run: This issue passed the CQ dry run.

[Benedikt Meurer, 2017-04-24 19:37:23]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2017-04-24 19:37:30]

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, 2017-04-24 19:40:03]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493062643027990, "parent_rev":
"83c058a98cc8f4e089f8cb82b728611e323bab94", "commit_rev":
"d853b2382e035ef6e4b38ebbc8de827570d076b2"}

[commit-bot: I haz the power, 2017-04-24 19:40:09]

Description was changed from

==========
[turbofan] Consolidate compatible element loads.

This changes behavior of TurboFan to match the behavior of Crankshaft
when it comes to polymorphic loads of similar elements kind (i.e. all
tagged or all double), where we should use the "worst case" code without
a transition. This is often much faster than transitioning the elements
to the worst case first, trading a TransitionElementsKind for a CheckMaps
and avoiding mutation of the array.

This is beneficial for various crypto benchmarks, which don't need to
pay the cost for TransitionElementsKind now.

R=jarin@chromium.org
BUG=v8:5267
==========

to

==========
[turbofan] Consolidate compatible element loads.

This changes behavior of TurboFan to match the behavior of Crankshaft
when it comes to polymorphic loads of similar elements kind (i.e. all
tagged or all double), where we should use the "worst case" code without
a transition. This is often much faster than transitioning the elements
to the worst case first, trading a TransitionElementsKind for a CheckMaps
and avoiding mutation of the array.

This is beneficial for various crypto benchmarks, which don't need to
pay the cost for TransitionElementsKind now.

R=jarin@chromium.org
BUG=v8:5267

Review-Url: https://codereview.chromium.org/2836943003
Cr-Commit-Position: refs/heads/master@{#44815}
Committed:
https://chromium.googlesource.com/v8/v8/+/d853b2382e035ef6e4b38ebbc8de827570d...
==========

[commit-bot: I haz the power, 2017-04-24 19:40:10]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/d853b2382e035ef6e4b38ebbc8de827570d...