[turbofan] ARM64: Use zr for zeroing stack slots

[turbofan] ARM64: Use zr for zeroing stack slots

When zeroing a floating point stack slot, store the zero register directly,
rather than storing zero moved to an FP register.

BUG=

Committed: https://crrev.com/f84f45f9ca808a0829df76bf9da712d4c1f51ed7
Cr-Commit-Position: refs/heads/master@{#39441}

[martyn.capewell, 2016-09-14 13:59:38]

martyn.capewell@arm.com changed reviewers:
+ bmeurer@chromium.org, epertoso@chromium.org

[Benedikt Meurer, 2016-09-14 16:48:14]

Cool stuff. LGTM.

[martyn.capewell, 2016-09-15 09:07:50]

The CQ bit was checked by martyn.capewell@arm.com

[commit-bot: I haz the power, 2016-09-15 09:07:57]

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, 2016-09-15 09:36:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-15 09:37:07]

Description was changed from

==========
[turbofan] ARM64: Use zr for zeroing stack slots

When zeroing a floating point stack slot, store the zero register directly,
rather than storing zero moved to an FP register.

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

to

==========
[turbofan] ARM64: Use zr for zeroing stack slots

When zeroing a floating point stack slot, store the zero register directly,
rather than storing zero moved to an FP register.

BUG=

Committed: https://crrev.com/f84f45f9ca808a0829df76bf9da712d4c1f51ed7
Cr-Commit-Position: refs/heads/master@{#39441}
==========

[commit-bot: I haz the power, 2016-09-15 09:37:08]

Patchset 1 (id:??) landed as
https://crrev.com/f84f45f9ca808a0829df76bf9da712d4c1f51ed7
Cr-Commit-Position: refs/heads/master@{#39441}