Remove useless branches in shrinking_reductions.

Remove useless branches in shrinking_reductions.

R=asgerf@google.com

Committed: https://github.com/dart-lang/sdk/commit/68c7404c4ad38562f4b3d8cdbf29f4924ae5d72b

[sra1, 2016-01-19 22:49:55]

sra@google.com changed reviewers:
+ asgerf@google.com

[asgerf, 2016-01-19 23:08:40]

LGTM!

https://codereview.chromium.org/1601863005/diff/1/pkg/compiler/lib/src/cps_ir...
File pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart (right):

https://codereview.chromium.org/1601863005/diff/1/pkg/compiler/lib/src/cps_ir...
pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart:211: if (value.isTrue) {
We have a helper for non-strict branches:

isTruthyConstant(value, strict: node.isStrictCheck)

It is defined in optimizers.dart, which is sort of a random place but it's there
when we need it.

https://codereview.chromium.org/1601863005/diff/1/pkg/compiler/lib/src/cps_ir...
pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart:424: // regardless of
where the letPrim is.
A constant pool would help here.

But there could also be an unused refinement in one of the branches, e.g if the
branch is "x == null".

(just some thoughts)

https://codereview.chromium.org/1601863005/diff/1/pkg/compiler/lib/src/cps_ir...
pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart:441: if
(trueInvoke.arguments.isNotEmpty) return false;
We should check the arguments for equality instead of bailing out.

Is it because of the LetPrim issue? It would still catch "cond ? x : x" until we
get the constant pool.

[sra1, 2016-01-20 01:00:26]

Patchset #2 (id:20001) has been deleted

[sra1, 2016-01-20 01:03:36]

https://codereview.chromium.org/1601863005/diff/1/pkg/compiler/lib/src/cps_ir...
File pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart (right):

https://codereview.chromium.org/1601863005/diff/1/pkg/compiler/lib/src/cps_ir...
pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart:211: if (value.isTrue) {
On 2016/01/19 23:08:39, asgerf wrote:
> We have a helper for non-strict branches:
> 
> isTruthyConstant(value, strict: node.isStrictCheck)
> 
> It is defined in optimizers.dart, which is sort of a random place but it's
there
> when we need it.

Done.

https://codereview.chromium.org/1601863005/diff/1/pkg/compiler/lib/src/cps_ir...
pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart:424: // regardless of
where the letPrim is.
On 2016/01/19 23:08:39, asgerf wrote:
> A constant pool would help here.
> 
> But there could also be an unused refinement in one of the branches, e.g if
the
> branch is "x == null".
> 
> (just some thoughts)

Acknowledged.

https://codereview.chromium.org/1601863005/diff/1/pkg/compiler/lib/src/cps_ir...
pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart:441: if
(trueInvoke.arguments.isNotEmpty) return false;
On 2016/01/19 23:08:39, asgerf wrote:
> We should check the arguments for equality instead of bailing out.
> 
> Is it because of the LetPrim issue? It would still catch "cond ? x : x" until
we
> get the constant pool.

"cond ? x : x" is a redundant phi, so I did not see it.

[sra1, 2016-01-20 01:41:13]

Description was changed from

==========
Remove useless branches in shrinking_reductions.
==========

to

==========
Remove useless branches in shrinking_reductions.

R=asgerf@google.com

Committed:
https://github.com/dart-lang/sdk/commit/68c7404c4ad38562f4b3d8cdbf29f4924ae5d72b
==========

[sra1, 2016-01-20 01:41:13]

Committed patchset #2 (id:40001) manually as
68c7404c4ad38562f4b3d8cdbf29f4924ae5d72b (presubmit successful).