trim some fat from SSE2 fixed point alpha code

trim some fat from SSE2 fixed point alpha code

  - extract alpha from a pixel: 5 1-cycle ops to 4 1-cycle ops
  - load alphas: drop 4 unnecessary ops

Should be no pixel diffs.

BUG=skia:
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Committed: https://skia.googlesource.com/skia/+/f769c1f80e12e595885376a03f1b99918f2fcd56

[mtklein, 2015-11-17 19:33:37]

Description was changed from

==========
trim some fat from SSE2 fixed point alpha code

  - extract alpha from a pixel: 5 1-cycle ops to 4 1-cycle ops
  - load alphas: drop 4 unnecessary ops

BUG=skia:
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot
==========

to

==========
trim some fat from SSE2 fixed point alpha code

  - extract alpha from a pixel: 5 1-cycle ops to 4 1-cycle ops
  - load alphas: drop 4 unnecessary ops

Should be no pixel diffs.

BUG=skia:
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot
==========

[mtklein, 2015-11-17 19:33:44]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-11-17 19:33:54]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1447273004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1447273004/1

[mtklein_C, 2015-11-17 19:44:19]

mtklein@chromium.org changed reviewers:
+ msarett@google.com
- mtklein@google.com

[commit-bot: I haz the power, 2015-11-17 19:45:56]

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

[commit-bot: I haz the power, 2015-11-17 19:45:57]

Dry run: This issue passed the CQ dry run.

[msarett, 2015-11-17 19:59:57]

lgtm

https://codereview.chromium.org/1447273004/diff/1/src/opts/Sk4px_SSE2.h
File src/opts/Sk4px_SSE2.h (right):

https://codereview.chromium.org/1447273004/diff/1/src/opts/Sk4px_SSE2.h#newco...
src/opts/Sk4px_SSE2.h:66: // We exploit that A >= rgb for any premul pixel.
Clever :)

[mtklein, 2015-11-17 20:05:09]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-11-17 20:05:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1447273004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1447273004/1

[commit-bot: I haz the power, 2015-11-17 20:05:59]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/f769c1f80e12e595885376a03f1b99918f2fcd56