Disallow tail calls from async functions and generators

Disallow tail calls from async functions and generators

Tail calls don't make sense from async functions and generators, as
each activation of these functions needs to make a new, distnict,
non-reused generator object. These tail calls are not required per
spec. This patch disables both syntactic and implicit tail calls
in async functions and generators.

R=neis
BUG=v8:5301, chromium:639270
Committed: https://crrev.com/5af4cd984067f4e316aea04ef381a00724b5a8bf
Cr-Commit-Position: refs/heads/master@{#38986}

[Dan Ehrenberg, 2016-08-26 22:13:18]

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

[commit-bot: I haz the power, 2016-08-26 22:13:26]

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, 2016-08-26 22:26:36]

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

[commit-bot: I haz the power, 2016-08-26 22:26:37]

Dry run: Try jobs failed on following builders:
  v8_linux64_avx2_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng/buil...)
  v8_linux64_avx2_rel_ng_triggered on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng_trig...)

[Dan Ehrenberg, 2016-08-26 22:34:40]

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

[commit-bot: I haz the power, 2016-08-26 22:34:42]

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, 2016-08-26 22:48:22]

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

[commit-bot: I haz the power, 2016-08-26 22:48:23]

Dry run: Try jobs failed on following builders:
  v8_linux64_gyp_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_gyp_rel_ng/build...)
  v8_linux64_gyp_rel_ng_triggered on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_gyp_rel_ng_trigg...)

[Dan Ehrenberg, 2016-08-26 22:50:38]

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

[commit-bot: I haz the power, 2016-08-26 22:50:46]

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, 2016-08-26 23:02:13]

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

[commit-bot: I haz the power, 2016-08-26 23:02:14]

Dry run: Try jobs failed on following builders:
  v8_linux64_gyp_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_gyp_rel_ng/build...)
  v8_linux64_gyp_rel_ng_triggered on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_gyp_rel_ng_trigg...)

[Dan Ehrenberg, 2016-08-26 23:15:49]

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

[commit-bot: I haz the power, 2016-08-26 23:15:53]

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, 2016-08-26 23:44:55]

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

[commit-bot: I haz the power, 2016-08-26 23:44:55]

Dry run: This issue passed the CQ dry run.

[neis, 2016-08-29 08:24:47]

Thanks! lgtm if i understand correctly that we don't need to change 
ParseArrowFunctionLiteral in parser-base.h (which has a similar condition)
because there are no generator arrow functions and async arrow functions are
already excluded by the time we do MarkTailPosition.

[neis, 2016-08-29 08:25:36]

On 2016/08/29 08:24:47, neis wrote:
> Thanks! lgtm if i understand correctly that we don't need to change 
> ParseArrowFunctionLiteral in parser-base.h (which has a similar condition)
> because there are no generator arrow functions and async arrow functions are
> already excluded by the time we do MarkTailPosition.

Maybe add a test case for that (async arrow with single expression body).

[Dan Ehrenberg, 2016-08-29 18:07:31]

The CQ bit was checked by littledan@chromium.org

[Dan Ehrenberg, 2016-08-29 18:07:31]

Added the suggested test.

[Dan Ehrenberg, 2016-08-29 18:07:32]

The patchset sent to the CQ was uploaded after l-g-t-m from neis@chromium.org
Link to the patchset: https://codereview.chromium.org/2278413003/#ps80001
(title: "Adding test suggested by neis")

[commit-bot: I haz the power, 2016-08-29 18:07:40]

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, 2016-08-29 18:31:21]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2016-08-29 18:31:48]

Description was changed from

==========
Disallow tail calls from async functions and generators

Tail calls don't make sense from async functions and generators, as
each activation of these functions needs to make a new, distnict,
non-reused generator object. These tail calls are not required per
spec. This patch disables both syntactic and implicit tail calls
in async functions and generators.

R=neis
BUG=v8:5301,chromium:639270
==========

to

==========
Disallow tail calls from async functions and generators

Tail calls don't make sense from async functions and generators, as
each activation of these functions needs to make a new, distnict,
non-reused generator object. These tail calls are not required per
spec. This patch disables both syntactic and implicit tail calls
in async functions and generators.

R=neis
BUG=v8:5301,chromium:639270

Committed: https://crrev.com/5af4cd984067f4e316aea04ef381a00724b5a8bf
Cr-Commit-Position: refs/heads/master@{#38986}
==========

[commit-bot: I haz the power, 2016-08-29 18:31:50]

Patchset 5 (id:??) landed as
https://crrev.com/5af4cd984067f4e316aea04ef381a00724b5a8bf
Cr-Commit-Position: refs/heads/master@{#38986}