[turbofan] Enable super constructor inlining.

[turbofan] Enable super constructor inlining.

When we inlined a [[Construct]] call to a subclass constructor, we can
also inline the super constructor call (either explicit or implicit),
since we have a concrete JSFunction constant for the subclass and we
can thus constant-fold the %_GetSuperConstructor intrinsic. We don't
need any guards here since the prototype of subclass constructors is
non-writable, non-configurable in ES6.

BUG=v8:5517
R=jarin@chromium.org

Committed: https://crrev.com/74158b00b3f6a1fc8676dd1f7af4d96131eb5ebe
Cr-Commit-Position: refs/heads/master@{#40261}

[Benedikt Meurer, 2016-10-13 12:28:58]

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

[commit-bot: I haz the power, 2016-10-13 12:29:07]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Jarin, 2016-10-13 12:32:46]

lgtm

[Benedikt Meurer, 2016-10-13 12:33:15]

The CQ bit was unchecked by bmeurer@chromium.org

[Benedikt Meurer, 2016-10-13 12:33:20]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-10-13 12:33:36]

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, 2016-10-13 12:56:12]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-10-13 12:56:36]

Description was changed from

==========
[turbofan] Enable super constructor inlining.

When we inlined a [[Construct]] call to a subclass constructor, we can
also inline the super constructor call (either explicit or implicit),
since we have a concrete JSFunction constant for the subclass and we
can thus constant-fold the %_GetSuperConstructor intrinsic. We don't
need any guards here since the prototype of subclass constructors is
non-writable, non-configurable in ES6.

BUG=v8:5517
R=jarin@chromium.org
==========

to

==========
[turbofan] Enable super constructor inlining.

When we inlined a [[Construct]] call to a subclass constructor, we can
also inline the super constructor call (either explicit or implicit),
since we have a concrete JSFunction constant for the subclass and we
can thus constant-fold the %_GetSuperConstructor intrinsic. We don't
need any guards here since the prototype of subclass constructors is
non-writable, non-configurable in ES6.

BUG=v8:5517
R=jarin@chromium.org

Committed: https://crrev.com/74158b00b3f6a1fc8676dd1f7af4d96131eb5ebe
Cr-Commit-Position: refs/heads/master@{#40261}
==========

[commit-bot: I haz the power, 2016-10-13 12:56:37]

Patchset 1 (id:??) landed as
https://crrev.com/74158b00b3f6a1fc8676dd1f7af4d96131eb5ebe
Cr-Commit-Position: refs/heads/master@{#40261}

[adamk, 2016-10-13 16:30:34]

adamk@chromium.org changed reviewers:
+ adamk@chromium.org

[adamk, 2016-10-13 16:30:34]

bmeurer wrote:
> We don't need any guards here since the prototype of subclass constructors is
> non-writable, non-configurable in ES6.

This is not true. The following code prints "Abra\nCadabra":

class A { constructor() { console.log('Abra') } }
class B extends A { }
new B();
B.__proto__ = class C { constructor() { console.log('Cadabra') } };
new B();

[Benedikt Meurer, 2016-10-13 18:03:15]

On 2016/10/13 16:30:34, adamk wrote:
> bmeurer wrote:
> > We don't need any guards here since the prototype of subclass constructors
is
> > non-writable, non-configurable in ES6.
> 
> This is not true. The following code prints "Abra\nCadabra":
> 
> class A { constructor() { console.log('Abra') } }
> class B extends A { }
> new B();
> B.__proto__ = class C { constructor() { console.log('Cadabra') } };
> new B();

Good catch, thanks.

[Benedikt Meurer, 2016-10-13 18:03:56]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2413883003/ by bmeurer@chromium.org.

The reason for reverting is: As adamk@ pointed out, this is not correct. Some
more changes required instead.