[turbofan] Remove the JSContextRelaxation reducer.

[turbofan] Remove the JSContextRelaxation reducer.

This reducer doesn't really add value, because:

 (a) it is only concerned with JSCallFunction and JSToNumber, but when
     we get to it, all JSCallFunction nodes will have been replaced by
     Call nodes, and in the not so far future, we will also have
     replaced almost all JSToNumber nodes with better code,
 (b) and the reducer tries to be smart and use one of the outermost
     contexts, but that might not be beneficial always; actually it
     might even create longer live ranges and lead to more spilling
     in some cases.

But most importantly, the JSContextRelaxation currently blocks inlining
based on SharedFunctionInfo, because it requires the inliner to check
the native context, which in turn requires JSFunction knowledge. So I'm
removing this reducer for now to unblock the more important inliner
changes.

R=jarin@chromium.org

Committed: https://crrev.com/8a7186b87a40adfa9e89a429688859f7986460c2
Cr-Commit-Position: refs/heads/master@{#34139}

[Benedikt Meurer, 2016-02-19 06:52:15]

Hey Jaro,

Here's another step for the inliner.
Please take a look.

Thanks,
Benedikt

[Jarin, 2016-02-19 07:01:50]

jarin@chromium.org changed reviewers:
+ danno@chromium.org

[Jarin, 2016-02-19 07:01:50]

jarin@chromium.org changed required reviewers:
+ danno@chromium.org

[Jarin, 2016-02-19 07:01:50]

lgtm, but @danno should have a look.

[danno, 2016-02-19 07:41:22]

This is fine with me. There is little benefit of this optimization if we won't
be generating stubs with TF.

[danno, 2016-02-19 07:42:37]

lgtm

[Benedikt Meurer, 2016-02-19 07:42:58]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-02-19 07:43:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1715633002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1715633002/1

[commit-bot: I haz the power, 2016-02-19 07:55:30]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-02-19 07:55:58]

Description was changed from

==========
[turbofan] Remove the JSContextRelaxation reducer.

This reducer doesn't really add value, because:

 (a) it is only concerned with JSCallFunction and JSToNumber, but when
     we get to it, all JSCallFunction nodes will have been replaced by
     Call nodes, and in the not so far future, we will also have
     replaced almost all JSToNumber nodes with better code,
 (b) and the reducer tries to be smart and use one of the outermost
     contexts, but that might not be beneficial always; actually it
     might even create longer live ranges and lead to more spilling
     in some cases.

But most importantly, the JSContextRelaxation currently blocks inlining
based on SharedFunctionInfo, because it requires the inliner to check
the native context, which in turn requires JSFunction knowledge. So I'm
removing this reducer for now to unblock the more important inliner
changes.

R=jarin@chromium.org
==========

to

==========
[turbofan] Remove the JSContextRelaxation reducer.

This reducer doesn't really add value, because:

 (a) it is only concerned with JSCallFunction and JSToNumber, but when
     we get to it, all JSCallFunction nodes will have been replaced by
     Call nodes, and in the not so far future, we will also have
     replaced almost all JSToNumber nodes with better code,
 (b) and the reducer tries to be smart and use one of the outermost
     contexts, but that might not be beneficial always; actually it
     might even create longer live ranges and lead to more spilling
     in some cases.

But most importantly, the JSContextRelaxation currently blocks inlining
based on SharedFunctionInfo, because it requires the inliner to check
the native context, which in turn requires JSFunction knowledge. So I'm
removing this reducer for now to unblock the more important inliner
changes.

R=jarin@chromium.org

Committed: https://crrev.com/8a7186b87a40adfa9e89a429688859f7986460c2
Cr-Commit-Position: refs/heads/master@{#34139}
==========

[commit-bot: I haz the power, 2016-02-19 07:55:59]

Patchset 1 (id:??) landed as
https://crrev.com/8a7186b87a40adfa9e89a429688859f7986460c2
Cr-Commit-Position: refs/heads/master@{#34139}