[turbofan] JSCreateClosure doesn't have any JS observable side effects.

[turbofan] JSCreateClosure doesn't have any JS observable side effects.

The JSCreateClosure operator was not marked as Eliminatable, esp. it
wasn't marked as NoWrite (read: no JavaScript observable side-effect),
which lead to a weird performance cliff with the new Array builtin
inlining. For example

  a.forEach(c => c);

was not inlined, whereas

  const f = c => c;
  a.forEach(f);

was properly inlined, despite not causing any trouble for TurboFan in
general. The reason was that the JSCreateClosure for the arrow function
was marked as "can cause potential side effect", which it cannot. This
fixes the operator to be properly marked as Eliminatable, thus removing
this performance cliff.

BUG=v8:1956, v8:6475
R=danno@chromium.org

Review-Url: https://codereview.chromium.org/2930933002
Cr-Commit-Position: refs/heads/master@{#45801}
Committed: https://chromium.googlesource.com/v8/v8/+/2a20ded9a163b2486a363c95c47b695cb453f273

[Benedikt Meurer, 2017-06-08 19:32:07]

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

[commit-bot: I haz the power, 2017-06-08 19:32:16]

Dry run: CQ is trying da patch.

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

[Benedikt Meurer, 2017-06-08 19:32:46]

Hey Danno,

Here's a simple fix for a performance cliff with forEach inlining. Please take a
look.

Thanks,
Benedikt

[Benedikt Meurer, 2017-06-08 19:40:31]

Description was changed from

==========
[turbofan] JSCreateClosure doesn't have any JS observable side effects.

The JSCreateClosure operator was not marked as Eliminatable, esp. it
wasn't marked as NoWrite (read: no JavaScript observable side-effect),
which lead to a weird performance cliff with the new Array builtin
inlining. For example

  a.forEach(c => c);

was not inlined, whereas

  const f = c => c;
  a.forEach(f);

was properly inlined, despite not causing any trouble for TurboFan in
general. The reason was that the JSCreateClosure for the arrow function
was marked as "can cause potential side effect", which it cannot. This
fixes the operator to be properly marked as Eliminatable, thus removing
this performance cliff.

BUG=v8:6475
R=danno@chromium.org
==========

to

==========
[turbofan] JSCreateClosure doesn't have any JS observable side effects.

The JSCreateClosure operator was not marked as Eliminatable, esp. it
wasn't marked as NoWrite (read: no JavaScript observable side-effect),
which lead to a weird performance cliff with the new Array builtin
inlining. For example

  a.forEach(c => c);

was not inlined, whereas

  const f = c => c;
  a.forEach(f);

was properly inlined, despite not causing any trouble for TurboFan in
general. The reason was that the JSCreateClosure for the arrow function
was marked as "can cause potential side effect", which it cannot. This
fixes the operator to be properly marked as Eliminatable, thus removing
this performance cliff.

BUG=v8:1956,v8:6475
R=danno@chromium.org
==========

[commit-bot: I haz the power, 2017-06-08 19:57:46]

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

[commit-bot: I haz the power, 2017-06-08 19:57:47]

Dry run: This issue passed the CQ dry run.

[danno, 2017-06-09 08:54:23]

lgtm

[Benedikt Meurer, 2017-06-09 09:01:54]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2017-06-09 09:02:00]

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, 2017-06-09 09:03:34]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1496998914224880, "parent_rev":
"4e86ae8c2c6ac8ab7564055eee5b91f71b32f72c", "commit_rev":
"2a20ded9a163b2486a363c95c47b695cb453f273"}

[commit-bot: I haz the power, 2017-06-09 09:03:41]

Description was changed from

==========
[turbofan] JSCreateClosure doesn't have any JS observable side effects.

The JSCreateClosure operator was not marked as Eliminatable, esp. it
wasn't marked as NoWrite (read: no JavaScript observable side-effect),
which lead to a weird performance cliff with the new Array builtin
inlining. For example

  a.forEach(c => c);

was not inlined, whereas

  const f = c => c;
  a.forEach(f);

was properly inlined, despite not causing any trouble for TurboFan in
general. The reason was that the JSCreateClosure for the arrow function
was marked as "can cause potential side effect", which it cannot. This
fixes the operator to be properly marked as Eliminatable, thus removing
this performance cliff.

BUG=v8:1956,v8:6475
R=danno@chromium.org
==========

to

==========
[turbofan] JSCreateClosure doesn't have any JS observable side effects.

The JSCreateClosure operator was not marked as Eliminatable, esp. it
wasn't marked as NoWrite (read: no JavaScript observable side-effect),
which lead to a weird performance cliff with the new Array builtin
inlining. For example

  a.forEach(c => c);

was not inlined, whereas

  const f = c => c;
  a.forEach(f);

was properly inlined, despite not causing any trouble for TurboFan in
general. The reason was that the JSCreateClosure for the arrow function
was marked as "can cause potential side effect", which it cannot. This
fixes the operator to be properly marked as Eliminatable, thus removing
this performance cliff.

BUG=v8:1956,v8:6475
R=danno@chromium.org

Review-Url: https://codereview.chromium.org/2930933002
Cr-Commit-Position: refs/heads/master@{#45801}
Committed:
https://chromium.googlesource.com/v8/v8/+/2a20ded9a163b2486a363c95c47b695cb45...
==========

[commit-bot: I haz the power, 2017-06-09 09:03:41]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/2a20ded9a163b2486a363c95c47b695cb45...