[arm64] Check sign with TBZ/TBNZ.

[arm64] Check sign with TBZ/TBNZ.

Generate TBZ/TBNZ for certain comparisons against zero. E.g. instead of:

    cmp w0, 0x0
    b.lt/ge <addr>

we can generate:

    tbnz/tbz w0, 31, <addr>

BUG=

Committed: https://crrev.com/5b81f5868d8a938b974cde56a9e2d9f75f650ddb
Cr-Commit-Position: refs/heads/master@{#39620}

[georgia.kouveli, 2016-09-22 09:51:23]

georgia.kouveli@arm.com changed reviewers:
+ bmeurer@chromium.org, epertoso@chromium.org

[Benedikt Meurer, 2016-09-22 09:52:59]

LGTM.

[georgia.kouveli, 2016-09-22 09:55:45]

The CQ bit was checked by georgia.kouveli@arm.com

[commit-bot: I haz the power, 2016-09-22 09:55:58]

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, 2016-09-22 10:24:39]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-22 10:25:05]

Description was changed from

==========
[arm64] Check sign with TBZ/TBNZ.

Generate TBZ/TBNZ for certain comparisons against zero. E.g. instead of:

    cmp w0, 0x0
    b.lt/ge <addr>

we can generate:

    tbnz/tbz w0, 31, <addr>

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

to

==========
[arm64] Check sign with TBZ/TBNZ.

Generate TBZ/TBNZ for certain comparisons against zero. E.g. instead of:

    cmp w0, 0x0
    b.lt/ge <addr>

we can generate:

    tbnz/tbz w0, 31, <addr>

BUG=

Committed: https://crrev.com/5b81f5868d8a938b974cde56a9e2d9f75f650ddb
Cr-Commit-Position: refs/heads/master@{#39620}
==========

[commit-bot: I haz the power, 2016-09-22 10:25:06]

Patchset 1 (id:??) landed as
https://crrev.com/5b81f5868d8a938b974cde56a9e2d9f75f650ddb
Cr-Commit-Position: refs/heads/master@{#39620}