dart2js cps: Translate identity placeholders to refinement nodes.

dart2js cps: Translate identity placeholders to refinement nodes.

This avoids emberrasing code like "x = x", and improves GVN, BCE, type
refinement etc, since all the optimizations now know that the input
and output values are the same.

BUG=
R=kmillikin@google.com

Committed: https://github.com/dart-lang/sdk/commit/719c1d227ad12651003d36e1e792ac4cf9a288b9

[asgerf, 2016-01-11 19:03:05]

asgerf@google.com changed reviewers:
+ kmillikin@google.com, sigmund@google.com, sra@google.com

[asgerf, 2016-01-11 19:03:05]

This causes regression because redundant phi elimination does not yet remove
phis where all inputs are refinements of the same value. I have added that to
our worklist, so for now I will not commit this, but it's here when we are ready
to land it.

[sra1, 2016-01-11 19:31:20]

https://codereview.chromium.org/1576063003/diff/40001/pkg/compiler/lib/src/js...
File pkg/compiler/lib/src/js/js.dart (right):

https://codereview.chromium.org/1576063003/diff/40001/pkg/compiler/lib/src/js...
pkg/compiler/lib/src/js/js.dart:170: return template.source == '#';
It would be better to check the ast for a placeholder, e.g. how it is done in
https://chromiumcodereview.appspot.com/1567103006/

[asgerf, 2016-01-11 20:11:44]

https://codereview.chromium.org/1576063003/diff/40001/pkg/compiler/lib/src/js...
File pkg/compiler/lib/src/js/js.dart (right):

https://codereview.chromium.org/1576063003/diff/40001/pkg/compiler/lib/src/js...
pkg/compiler/lib/src/js/js.dart:170: return template.source == '#';
On 2016/01/11 19:31:20, sra1 wrote:
> It would be better to check the ast for a placeholder, e.g. how it is done in
> https://chromiumcodereview.appspot.com/1567103006/

Replaced with an is-check.

[asgerf, 2016-01-22 23:20:55]

Description was changed from

==========
dart2js cps: Translate identity placeholders to refinement nodes.

This avoids emberrasing code like "x = x", and improves GVN, BCE, type
refinement etc, since all the optimizations now know that the input
and output values are the same.

BUG=
==========

to

==========
dart2js cps: Translate identity placeholders to refinement nodes.

This avoids emberrasing code like "x = x", and improves GVN, BCE, type
refinement etc, since all the optimizations now know that the input
and output values are the same.

FIXES #25448

BUG=
==========

[asgerf, 2016-01-22 23:21:04]

Description was changed from

==========
dart2js cps: Translate identity placeholders to refinement nodes.

This avoids emberrasing code like "x = x", and improves GVN, BCE, type
refinement etc, since all the optimizations now know that the input
and output values are the same.

FIXES #25448

BUG=
==========

to

==========
dart2js cps: Translate identity placeholders to refinement nodes.

This avoids emberrasing code like "x = x", and improves GVN, BCE, type
refinement etc, since all the optimizations now know that the input
and output values are the same.

BUG=
==========

[Kevin Millikin (Google), 2016-01-26 08:10:33]

And LGTM.

[asgerf, 2016-01-26 08:58:30]

Description was changed from

==========
dart2js cps: Translate identity placeholders to refinement nodes.

This avoids emberrasing code like "x = x", and improves GVN, BCE, type
refinement etc, since all the optimizations now know that the input
and output values are the same.

BUG=
==========

to

==========
dart2js cps: Translate identity placeholders to refinement nodes.

This avoids emberrasing code like "x = x", and improves GVN, BCE, type
refinement etc, since all the optimizations now know that the input
and output values are the same.

BUG=
R=kmillikin@google.com

Committed:
https://github.com/dart-lang/sdk/commit/719c1d227ad12651003d36e1e792ac4cf9a288b9
==========

[asgerf, 2016-01-26 08:58:32]

Committed patchset #8 (id:140001) manually as
719c1d227ad12651003d36e1e792ac4cf9a288b9 (presubmit successful).