[turbofan] Constant-fold some ObjectIs checks based on feedback type.

[turbofan] Constant-fold some ObjectIs checks based on feedback type.

During feedback typing (in SimplifiedLowering) we might be able to
constant-fold a bunch of ObjectIs<Type> predicates, i.e. because we
took type feedback on the input or we narrowed the type of a Phi
because of type feedback.

R=mvstanton@chromium.org
BUG=v8:5267, v8:5270
Committed: https://crrev.com/347931e6273484c97c7b6e065f6b0e500ed089f6
Cr-Commit-Position: refs/heads/master@{#39468}

[Benedikt Meurer, 2016-09-16 07:31:13]

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

[commit-bot: I haz the power, 2016-09-16 07:31:16]

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

[Benedikt Meurer, 2016-09-16 07:31:42]

Hey Michael,

Here's some low-hanging fruit to pick.
Please take a look.

Thanks,
Benedikt

[commit-bot: I haz the power, 2016-09-16 07:33:14]

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

[commit-bot: I haz the power, 2016-09-16 07:33:15]

Dry run: Try jobs failed on following builders:
  v8_win64_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_win64_rel_ng/builds/14399)
  v8_win_nosnap_shared_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_win_nosnap_shared_rel_ng...)

[mvstanton, 2016-09-16 08:52:51]

lgtm

[Benedikt Meurer, 2016-09-16 08:55:36]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2016-09-16 08:55:36]

The patchset sent to the CQ was uploaded after l-g-t-m from
mvstanton@chromium.org
Link to the patchset: https://codereview.chromium.org/2342283002/#ps20001
(title: "REBASE")

[commit-bot: I haz the power, 2016-09-16 08:55:40]

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, 2016-09-16 09:20:15]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-09-16 09:21:19]

Description was changed from

==========
[turbofan] Constant-fold some ObjectIs checks based on feedback type.

During feedback typing (in SimplifiedLowering) we might be able to
constant-fold a bunch of ObjectIs<Type> predicates, i.e. because we
took type feedback on the input or we narrowed the type of a Phi
because of type feedback.

R=mvstanton@chromium.org
BUG=v8:5267,v8:5270
==========

to

==========
[turbofan] Constant-fold some ObjectIs checks based on feedback type.

During feedback typing (in SimplifiedLowering) we might be able to
constant-fold a bunch of ObjectIs<Type> predicates, i.e. because we
took type feedback on the input or we narrowed the type of a Phi
because of type feedback.

R=mvstanton@chromium.org
BUG=v8:5267,v8:5270

Committed: https://crrev.com/347931e6273484c97c7b6e065f6b0e500ed089f6
Cr-Commit-Position: refs/heads/master@{#39468}
==========

[commit-bot: I haz the power, 2016-09-16 09:21:20]

Patchset 2 (id:??) landed as
https://crrev.com/347931e6273484c97c7b6e065f6b0e500ed089f6
Cr-Commit-Position: refs/heads/master@{#39468}

[Jarin, 2016-09-16 15:37:10]

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

[Jarin, 2016-09-16 15:37:11]

https://codereview.chromium.org/2342283002/diff/20001/src/compiler/simplified...
File src/compiler/simplified-lowering.cc (right):

https://codereview.chromium.org/2342283002/diff/20001/src/compiler/simplified...
src/compiler/simplified-lowering.cc:917: VisitUnop(node, UseInfo::None(),
MachineRepresentation::kBit);
Does it really buy you anything to send UseInfo::None here?

I am mildly uncomfortable with this because this can change truncation after the
truncation pass (fortunately, only in the good direction, but still...).

Would it be really that bad to do "VisitUnop(node, UseInfo::AnyTagged(),
MachineRepresentation::kBit);" unconditionally?

[Benedikt Meurer, 2016-09-16 17:14:33]

https://codereview.chromium.org/2342283002/diff/20001/src/compiler/simplified...
File src/compiler/simplified-lowering.cc (right):

https://codereview.chromium.org/2342283002/diff/20001/src/compiler/simplified...
src/compiler/simplified-lowering.cc:917: VisitUnop(node, UseInfo::None(),
MachineRepresentation::kBit);
I guess that would work. Do you want me to change that?