PPC: Clean up register save/restore logic.

PPC: Clean up register save/restore logic.

NOPRESUBMIT=true
R=titzer@chromium.org, michael_dawson@ca.ibm.com, jyan@ca.ibm.com, joransiu@ca.ibm.com
BUG=

Committed: https://crrev.com/e16cfe562d5dc142eb604002afb3d0e4dfca663e
Cr-Commit-Position: refs/heads/master@{#29978}

[MTBrandyberry, 2015-07-31 18:55:02]

Including titzer due to the change to src/compiler/c-linkage.cc.

[JoranSiu, 2015-07-31 19:31:16]

lgtm

[MTBrandyberry, 2015-07-31 19:34:58]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-07-31 19:35:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1271583002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1271583002/1

[commit-bot: I haz the power, 2015-07-31 19:38:09]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-31 19:38:10]

Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/4609)

[john.yan, 2015-07-31 20:29:18]

lgtm

[MTBrandyberry, 2015-08-03 13:24:01]

On 2015/07/31 20:29:18, john.yan wrote:
> lgtm

Still need approval from src/compiler owner @titzer.

[titzer, 2015-08-03 13:25:20]

lgtm

[MTBrandyberry, 2015-08-03 13:25:43]

On 2015/08/03 13:25:20, titzer wrote:
> lgtm

Thank you!

[MTBrandyberry, 2015-08-03 13:25:47]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-08-03 13:26:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1271583002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1271583002/1

[commit-bot: I haz the power, 2015-08-03 13:28:58]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-03 13:28:59]

Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/4636)

[MTBrandyberry, 2015-08-03 13:33:48]

On 2015/08/03 13:28:59, commit-bot: I haz the power wrote:
> Try jobs failed on following builders:
>   v8_presubmit on tryserver.v8 (JOB_FAILED,
> http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/4636)

Hmmm.. Presubmit failure due to a change in another CL.  Not sure how to
proceed.

[titzer, 2015-08-03 13:55:24]

On 2015/08/03 13:33:48, mtbrandyberry wrote:
> On 2015/08/03 13:28:59, commit-bot: I haz the power wrote:
> > Try jobs failed on following builders:
> >   v8_presubmit on tryserver.v8 (JOB_FAILED,
> > http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/4636)
> 
> Hmmm.. Presubmit failure due to a change in another CL.  Not sure how to
> proceed.

Fix in flight: https://codereview.chromium.org/1263363002/

[MTBrandyberry, 2015-08-03 14:36:28]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-08-03 14:36:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1271583002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1271583002/1

[commit-bot: I haz the power, 2015-08-03 14:36:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-03 14:37:03]

Patchset 1 (id:??) landed as
https://crrev.com/e16cfe562d5dc142eb604002afb3d0e4dfca663e
Cr-Commit-Position: refs/heads/master@{#29978}