[turbofan] Avoid allocating rest parameters for spread calls.

[turbofan] Avoid allocating rest parameters for spread calls.

We already had an optimization to turn Function.prototype.apply with
arguments object, i.e.

  function foo() { return bar.apply(this, arguments); }

into a special operator JSCallForwardVarargs, which avoids the
allocation and deconstruction of the arguments object, but just passes
along the incoming parameters. We can do the same for rest parameters
and spread calls/constructs, i.e.

  class A extends B {
    constructor(...args) { super(...args); }
  }

or

  function foo(...args) { return bar(1, 2, 3, ...args); }

where we basically pass along the parameters (plus maybe additional
statically known parameters).

For this, we introduce a new JSConstructForwardVarargs operator and
generalize the CallForwardVarargs builtins that are backing this.

BUG=v8:6407, v8:6278, v8:6344
R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2890023004
Cr-Commit-Position: refs/heads/master@{#45388}
Committed: https://chromium.googlesource.com/v8/v8/+/bfa319e5d3f902e504c00af5607117d1eb5d6273

[Benedikt Meurer, 2017-05-18 05:58:21]

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

[commit-bot: I haz the power, 2017-05-18 05:58:30]

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, 2017-05-18 06:33:28]

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

[commit-bot: I haz the power, 2017-05-18 06:33:29]

Dry run: This issue passed the CQ dry run.

[Jarin, 2017-05-18 07:01:06]

lgtm

Do we have test coverage for all the combinations of arguments counts and kinds?
If not, please add mjsunit tests that exercise these code paths.

[Benedikt Meurer, 2017-05-18 07:30:03]

Sprinkled some UNREACHABLEs and the tests hit them.

[Benedikt Meurer, 2017-05-18 07:30:08]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2017-05-18 07:30:20]

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, 2017-05-18 07:32:23]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1495092608256450, "parent_rev":
"8038e5cac45824d792c2ef91a7cc273ca242b864", "commit_rev":
"bfa319e5d3f902e504c00af5607117d1eb5d6273"}

[commit-bot: I haz the power, 2017-05-18 07:32:32]

Description was changed from

==========
[turbofan] Avoid allocating rest parameters for spread calls.

We already had an optimization to turn Function.prototype.apply with
arguments object, i.e.

  function foo() { return bar.apply(this, arguments); }

into a special operator JSCallForwardVarargs, which avoids the
allocation and deconstruction of the arguments object, but just passes
along the incoming parameters. We can do the same for rest parameters
and spread calls/constructs, i.e.

  class A extends B {
    constructor(...args) { super(...args); }
  }

or

  function foo(...args) { return bar(1, 2, 3, ...args); }

where we basically pass along the parameters (plus maybe additional
statically known parameters).

For this, we introduce a new JSConstructForwardVarargs operator and
generalize the CallForwardVarargs builtins that are backing this.

BUG=v8:6407,v8:6278,v8:6344
R=jarin@chromium.org
==========

to

==========
[turbofan] Avoid allocating rest parameters for spread calls.

We already had an optimization to turn Function.prototype.apply with
arguments object, i.e.

  function foo() { return bar.apply(this, arguments); }

into a special operator JSCallForwardVarargs, which avoids the
allocation and deconstruction of the arguments object, but just passes
along the incoming parameters. We can do the same for rest parameters
and spread calls/constructs, i.e.

  class A extends B {
    constructor(...args) { super(...args); }
  }

or

  function foo(...args) { return bar(1, 2, 3, ...args); }

where we basically pass along the parameters (plus maybe additional
statically known parameters).

For this, we introduce a new JSConstructForwardVarargs operator and
generalize the CallForwardVarargs builtins that are backing this.

BUG=v8:6407,v8:6278,v8:6344
R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2890023004
Cr-Commit-Position: refs/heads/master@{#45388}
Committed:
https://chromium.googlesource.com/v8/v8/+/bfa319e5d3f902e504c00af5607117d1eb5...
==========

[commit-bot: I haz the power, 2017-05-18 07:32:32]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/bfa319e5d3f902e504c00af5607117d1eb5...