MIPS64: Fix corner case for Word64And(Word64Shr(val,0)) reduction

MIPS64: Fix corner case for Word64And(Word64Shr(val,0)) reduction

In instruction selector, in the reduction of Word64And(Word64Shr(val,0),
0xFFF...) to EXT instruction, the case where shift value is 0 and mask is
0xFFFFFFFFFFFFFFFF was not supported. We now generate NOP for this case
since no bit extraction is necessary.
We implement the same behavior for MIPS32 even though there are no tests
that are failing.

TEST=cctest/test-run-machops/Regression5951
BUG=

Review-Url: https://codereview.chromium.org/2718433002
Cr-Commit-Position: refs/heads/master@{#43408}
Committed: https://chromium.googlesource.com/v8/v8/+/5b8f1f84a4316da06103fab2d970f05d14e45993

[ivica.bogosavljevic, 2017-02-23 11:02:43]

ivica.bogosavljevic@imgtec.com changed reviewers:
+ miran.karic@imgtec.com

[ivica.bogosavljevic, 2017-02-23 11:02:44]

PTAL

[miran.karic, 2017-02-23 12:50:34]

miran.karic@imgtec.com changed reviewers:
+ Miran.Karic@imgtec.com

[miran.karic, 2017-02-23 12:50:34]

lgtm

[ivica.bogosavljevic, 2017-02-24 09:35:49]

The CQ bit was checked by ivica.bogosavljevic@imgtec.com

[commit-bot: I haz the power, 2017-02-24 09:35:55]

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, 2017-02-24 09:58:12]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1487928949256700, "parent_rev":
"208014abea8fff770b149cd52d10a4acbfa745dd", "commit_rev":
"5b8f1f84a4316da06103fab2d970f05d14e45993"}

[commit-bot: I haz the power, 2017-02-24 09:58:16]

Description was changed from

==========
MIPS64: Fix corner case for Word64And(Word64Shr(val,0)) reduction

In instruction selector, in the reduction of Word64And(Word64Shr(val,0),
0xFFF...) to EXT instruction, the case where shift value is 0 and mask is
0xFFFFFFFFFFFFFFFF was not supported. We now generate NOP for this case
since no bit extraction is necessary.
We implement the same behavior for MIPS32 even though there are no tests
that are failing.

TEST=cctest/test-run-machops/Regression5951
BUG=
==========

to

==========
MIPS64: Fix corner case for Word64And(Word64Shr(val,0)) reduction

In instruction selector, in the reduction of Word64And(Word64Shr(val,0),
0xFFF...) to EXT instruction, the case where shift value is 0 and mask is
0xFFFFFFFFFFFFFFFF was not supported. We now generate NOP for this case
since no bit extraction is necessary.
We implement the same behavior for MIPS32 even though there are no tests
that are failing.

TEST=cctest/test-run-machops/Regression5951
BUG=

Review-Url: https://codereview.chromium.org/2718433002
Cr-Commit-Position: refs/heads/master@{#43408}
Committed:
https://chromium.googlesource.com/v8/v8/+/5b8f1f84a4316da06103fab2d970f05d14e...
==========

[commit-bot: I haz the power, 2017-02-24 09:58:19]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/5b8f1f84a4316da06103fab2d970f05d14e...