[x64] Make xmm0 allocatable and use xmm15 as scratch register instead.

[x64] Make xmm0 allocatable and use xmm15 as scratch register instead.

The idea is to make it easier (cheaper) to call into C/C++ directly with
C calling conventions, which require xmm0 to be used to pass and return
floating point values in the future.

R=jarin@chromium.org

Committed: https://crrev.com/32820ddf9269ac725f0a52b61142462db70374eb
Cr-Commit-Position: refs/heads/master@{#36646}

[Jarin, 2016-06-01 12:32:10]

lgtm

[Benedikt Meurer, 2016-06-01 12:32:38]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-06-01 12:32:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2023763010/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/2023763010/1

[commit-bot: I haz the power, 2016-06-01 13:05:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-06-01 13:05:41]

Description was changed from

==========
[x64] Make xmm0 allocatable and use xmm15 as scratch register instead.

The idea is to make it easier (cheaper) to call into C/C++ directly with
C calling conventions, which require xmm0 to be used to pass and return
floating point values in the future.

R=jarin@chromium.org
==========

to

==========
[x64] Make xmm0 allocatable and use xmm15 as scratch register instead.

The idea is to make it easier (cheaper) to call into C/C++ directly with
C calling conventions, which require xmm0 to be used to pass and return
floating point values in the future.

R=jarin@chromium.org

Committed: https://crrev.com/32820ddf9269ac725f0a52b61142462db70374eb
Cr-Commit-Position: refs/heads/master@{#36646}
==========

[commit-bot: I haz the power, 2016-06-01 13:05:41]

Patchset 1 (id:??) landed as
https://crrev.com/32820ddf9269ac725f0a52b61142462db70374eb
Cr-Commit-Position: refs/heads/master@{#36646}