[turbofan] Strength reduce CheckTaggedSigned/Pointer with checked inputs.

[turbofan] Strength reduce CheckTaggedSigned/Pointer with checked inputs.

Add strength reduction rules to optimize

 CheckTaggedSigned(CheckTaggedSigned(x)) -> CheckTaggedSigned(x)

and

 CheckTaggedPointer(CheckTaggedPointer(x)) -> CheckTaggedPointer(x)

where we do some cleanup optimizations after loop peeling and redundancy
elimination, which can generate these constructs.

BUG=v8:5267
Committed: https://crrev.com/dfc4b47f661d7cde5fa23112c19e3f146526d0d3
Cr-Commit-Position: refs/heads/master@{#39366}

[Benedikt Meurer, 2016-09-13 06:02:28]

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

[commit-bot: I haz the power, 2016-09-13 06:02:34]

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

[Benedikt Meurer, 2016-09-13 06:23:29]

bmeurer@chromium.org changed reviewers:
+ mvstanton@chromium.org

[Benedikt Meurer, 2016-09-13 06:23:29]

Hey Michael,

Simple optimization to cleanup after loop peeling/load elimination.
Please take a look.

Thanks,
Benedikt

[mvstanton, 2016-09-13 06:27:05]

lgtm(lgtm) -> lgtm.

[Benedikt Meurer, 2016-09-13 06:27:15]

The CQ bit was unchecked by bmeurer@chromium.org

[Benedikt Meurer, 2016-09-13 06:27:20]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-09-13 06:27:24]

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, 2016-09-13 06:31:57]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-13 06:32:13]

Description was changed from

==========
[turbofan] Strength reduce CheckTaggedSigned/Pointer with checked inputs.

Add strength reduction rules to optimize

 CheckTaggedSigned(CheckTaggedSigned(x)) -> CheckTaggedSigned(x)

and

 CheckTaggedPointer(CheckTaggedPointer(x)) -> CheckTaggedPointer(x)

where we do some cleanup optimizations after loop peeling and redundancy
elimination, which can generate these constructs.

BUG=v8:5267
==========

to

==========
[turbofan] Strength reduce CheckTaggedSigned/Pointer with checked inputs.

Add strength reduction rules to optimize

 CheckTaggedSigned(CheckTaggedSigned(x)) -> CheckTaggedSigned(x)

and

 CheckTaggedPointer(CheckTaggedPointer(x)) -> CheckTaggedPointer(x)

where we do some cleanup optimizations after loop peeling and redundancy
elimination, which can generate these constructs.

BUG=v8:5267

Committed: https://crrev.com/dfc4b47f661d7cde5fa23112c19e3f146526d0d3
Cr-Commit-Position: refs/heads/master@{#39366}
==========

[commit-bot: I haz the power, 2016-09-13 06:32:14]

Patchset 1 (id:??) landed as
https://crrev.com/dfc4b47f661d7cde5fa23112c19e3f146526d0d3
Cr-Commit-Position: refs/heads/master@{#39366}