[promise] separate PerformPromiseThen from PromiseThen

[promise] separate PerformPromiseThen from PromiseThen

The `PerformPromiseThen` spec-internal operation is used by the async functions
proposal, in order to ensure that AwaitExpressions are not observable via
usual mechanisms/hooks, such as Symbol.species.

BUG=v8:5253
R=littledan@chromium.org, adamk@chromium.org, gsathya@chromium.org, yangguo@chromium.org

Committed: https://crrev.com/0272aa502fbc9874cadfca81199a83c38f95eb88
Cr-Commit-Position: refs/heads/master@{#38353}

[caitp, 2016-08-02 20:15:38]

Hi, please take a quick look.

This is not quite ready yet, it breaks
https://codereview.chromium.org/2124813002 a little bit. In particular, an
Exception event is reached at the "    await thrower();" line of
test/mjsunit/harmony/async-debug-caught-exception.js, for some reason.

I'm looking into this, but have not yet found what's causing it. Likely due to
how I've structured PerformPromiseThen.

[Dan Ehrenberg, 2016-08-02 20:20:57]

lgtm

https://codereview.chromium.org/2209433003/diff/1/src/js/harmony-async-await.js
File src/js/harmony-async-await.js (right):

https://codereview.chromium.org/2209433003/diff/1/src/js/harmony-async-await....
src/js/harmony-async-await.js:42: var throwawayCapability =
NewPromiseCapability(GlobalPromise);
I'm a big fan of how this exactly mirrors the spec. Do you have any ideas for
how we may optimize away some of these allocations?

[caitp, 2016-08-02 20:40:20]

https://codereview.chromium.org/2209433003/diff/1/src/js/harmony-async-await.js
File src/js/harmony-async-await.js (right):

https://codereview.chromium.org/2209433003/diff/1/src/js/harmony-async-await....
src/js/harmony-async-await.js:42: var throwawayCapability =
NewPromiseCapability(GlobalPromise);
On 2016/08/02 20:20:56, Dan Ehrenberg wrote:
> I'm a big fan of how this exactly mirrors the spec. Do you have any ideas for
> how we may optimize away some of these allocations?

I assume that's meant to be "I'm not a big fan of ...", given the question?

Might be able to avoid some stuff for the Promise.resolve(), but the part
emulating Promise.prototype.then() needs all of it, I believe.

[Dan Ehrenberg, 2016-08-02 20:54:46]

https://codereview.chromium.org/2209433003/diff/1/src/js/harmony-async-await.js
File src/js/harmony-async-await.js (right):

https://codereview.chromium.org/2209433003/diff/1/src/js/harmony-async-await....
src/js/harmony-async-await.js:42: var throwawayCapability =
NewPromiseCapability(GlobalPromise);
On 2016/08/02 at 20:40:20, caitp wrote:
> On 2016/08/02 20:20:56, Dan Ehrenberg wrote:
> > I'm a big fan of how this exactly mirrors the spec. Do you have any ideas
for
> > how we may optimize away some of these allocations?
> 
> I assume that's meant to be "I'm not a big fan of ...", given the question?
> 
> Might be able to avoid some stuff for the Promise.resolve(), but the part
emulating Promise.prototype.then() needs all of it, I believe.

Yeah, this does seem tricky. I definitely didn't mean the comment to delay
committing this change; it seems good to me as is.

[caitp, 2016-08-02 21:29:44]

On 2016/08/02 20:54:46, Dan Ehrenberg wrote:
>
https://codereview.chromium.org/2209433003/diff/1/src/js/harmony-async-await.js
> File src/js/harmony-async-await.js (right):
> 
>
https://codereview.chromium.org/2209433003/diff/1/src/js/harmony-async-await....
> src/js/harmony-async-await.js:42: var throwawayCapability =
> NewPromiseCapability(GlobalPromise);
> On 2016/08/02 at 20:40:20, caitp wrote:
> > On 2016/08/02 20:20:56, Dan Ehrenberg wrote:
> > > I'm a big fan of how this exactly mirrors the spec. Do you have any ideas
> for
> > > how we may optimize away some of these allocations?
> > 
> > I assume that's meant to be "I'm not a big fan of ...", given the question?
> > 
> > Might be able to avoid some stuff for the Promise.resolve(), but the part
> emulating Promise.prototype.then() needs all of it, I believe.
> 
> Yeah, this does seem tricky. I definitely didn't mean the comment to delay
> committing this change; it seems good to me as is.

as mentioned, this does break a debug test, so I'd like a look from Yang

[Dan Ehrenberg, 2016-08-02 21:37:28]

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

[commit-bot: I haz the power, 2016-08-02 21:37:39]

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, 2016-08-02 21:48:29]

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

[commit-bot: I haz the power, 2016-08-02 21:48:30]

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...)

[caitp, 2016-08-04 18:51:35]

Ping Yang: Can you let me know if I'm missing any obvious reason as to why this
breaks the catch prediction stuff? as far as I can tell it should behave pretty
much equivalently to the original code

[caitp, 2016-08-04 19:16:36]

The CQ bit was checked by caitp@igalia.com to run a CQ dry run

[commit-bot: I haz the power, 2016-08-04 19:16:48]

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, 2016-08-04 19:29:09]

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

[commit-bot: I haz the power, 2016-08-04 19:29:10]

Dry run: Try jobs failed on following builders:
  v8_linux_dbg_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_dbg_ng/builds/10347)
  v8_linux_dbg_ng_triggered on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_dbg_ng_triggered/b...)

[Dan Ehrenberg, 2016-08-04 21:15:04]

On 2016/08/04 at 18:51:35, caitp wrote:
> Ping Yang: Can you let me know if I'm missing any obvious reason as to why
this breaks the catch prediction stuff? as far as I can tell it should behave
pretty much equivalently to the original code

Here's a version of your patch which passes the debugger tests:
https://codereview.chromium.org/2218563002 . However, there are some other
failures in the new test on certain platforms.

[caitp, 2016-08-04 21:53:25]

The CQ bit was checked by caitp@igalia.com to run a CQ dry run

[commit-bot: I haz the power, 2016-08-04 21:53:36]

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, 2016-08-04 22:36:57]

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

[commit-bot: I haz the power, 2016-08-04 22:36:58]

Dry run: This issue passed the CQ dry run.

[Dan Ehrenberg, 2016-08-04 22:47:45]

lgtm

[caitp, 2016-08-04 22:52:35]

The CQ bit was checked by caitp@igalia.com

[commit-bot: I haz the power, 2016-08-04 22:52:38]

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, 2016-08-04 22:54:21]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-08-04 22:56:53]

Description was changed from

==========
[promise] separate PerformPromiseThen from PromiseThen

The `PerformPromiseThen` spec-internal operation is used by the async functions
proposal, in order to ensure that AwaitExpressions are not observable via
usual mechanisms/hooks, such as Symbol.species.

BUG=v8:5253
R=littledan@chromium.org, adamk@chromium.org, gsathya@chromium.org,
yangguo@chromium.org
==========

to

==========
[promise] separate PerformPromiseThen from PromiseThen

The `PerformPromiseThen` spec-internal operation is used by the async functions
proposal, in order to ensure that AwaitExpressions are not observable via
usual mechanisms/hooks, such as Symbol.species.

BUG=v8:5253
R=littledan@chromium.org, adamk@chromium.org, gsathya@chromium.org,
yangguo@chromium.org

Committed: https://crrev.com/0272aa502fbc9874cadfca81199a83c38f95eb88
Cr-Commit-Position: refs/heads/master@{#38353}
==========

[commit-bot: I haz the power, 2016-08-04 22:56:54]

Patchset 2 (id:??) landed as
https://crrev.com/0272aa502fbc9874cadfca81199a83c38f95eb88
Cr-Commit-Position: refs/heads/master@{#38353}