Add Sk4h_load4 for loading F16.

Add Sk4h_load4 for loading F16.

Should feel very similar to Sk4h_store4:
NEON uses its native instruction, SSE unpacks manually.

Since we'll have our F16s in 4 Sk4h by the time we're done here,
this also extracts an Sk4h->Sk4f routine from the old uint64_t->Sk4f one.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2184753002
CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Committed: https://skia.googlesource.com/skia/+/f660b7cfcfbf3062f88e61f8320ea7051da72213

[mtklein_C, 2016-07-26 13:48:40]

Description was changed from

==========
Add Sk4h_load4 for loading F16.

Should feel very similar to Sk4h_store4:
NEON uses its native instruction, SSE unpacks manually.

Since we'll have our F16s in 4 Sk4h by the time we're done here,
this also extracts an Sk4h->Sk4f routine from the old uint64_t->Sk4f one.

BUG=skia:
==========

to

==========
Add Sk4h_load4 for loading F16.

Should feel very similar to Sk4h_store4:
NEON uses its native instruction, SSE unpacks manually.

Since we'll have our F16s in 4 Sk4h by the time we're done here,
this also extracts an Sk4h->Sk4f routine from the old uint64_t->Sk4f one.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2184753002
CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot
==========

[mtklein_C, 2016-07-26 13:53:15]

The CQ bit was checked by mtklein@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-26 13:53:26]

Dry run: 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, 2016-07-26 13:56:55]

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

[commit-bot: I haz the power, 2016-07-26 13:56:56]

Dry run: Try jobs failed on following builders:
  Build-Ubuntu-GCC-Mips-Debug-Android-Trybot on master.client.skia.compile
(JOB_FAILED,
http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-GCC-Mip...)

[mtklein_C, 2016-07-26 14:09:18]

The CQ bit was checked by mtklein@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-26 14:09:22]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[mtklein_C, 2016-07-26 14:11:10]

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

[msarett, 2016-07-26 14:25:07]

lgtm

https://codereview.chromium.org/2184753002/diff/20001/src/opts/SkNx_sse.h
File src/opts/SkNx_sse.h (right):

https://codereview.chromium.org/2184753002/diff/20001/src/opts/SkNx_sse.h#new...
src/opts/SkNx_sse.h:406: static inline void Sk4h_load4(const void* ptr, Sk4h* r,
Sk4h* g, Sk4h* b, Sk4h* a) {
The fact that we are doing a transpose on loads and stores of F16 makes me think
we should consider planar...

[commit-bot: I haz the power, 2016-07-26 14:31:08]

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

[commit-bot: I haz the power, 2016-07-26 14:31:08]

Dry run: This issue passed the CQ dry run.

[mtklein, 2016-07-26 14:59:56]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2016-07-26 15:00:06]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[mtklein, 2016-07-26 15:00:48]

mtklein@google.com changed reviewers:
+ brianosman@google.com, bsalomon@google.com

[mtklein, 2016-07-26 15:00:49]

+Brians, is planar half float a format that's realistic to expect GPUs support?

[commit-bot: I haz the power, 2016-07-26 15:01:22]

Description was changed from

==========
Add Sk4h_load4 for loading F16.

Should feel very similar to Sk4h_store4:
NEON uses its native instruction, SSE unpacks manually.

Since we'll have our F16s in 4 Sk4h by the time we're done here,
this also extracts an Sk4h->Sk4f routine from the old uint64_t->Sk4f one.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2184753002
CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot
==========

to

==========
Add Sk4h_load4 for loading F16.

Should feel very similar to Sk4h_store4:
NEON uses its native instruction, SSE unpacks manually.

Since we'll have our F16s in 4 Sk4h by the time we're done here,
this also extracts an Sk4h->Sk4f routine from the old uint64_t->Sk4f one.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2184753002
CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Committed:
https://skia.googlesource.com/skia/+/f660b7cfcfbf3062f88e61f8320ea7051da72213
==========

[commit-bot: I haz the power, 2016-07-26 15:01:23]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/f660b7cfcfbf3062f88e61f8320ea7051da72213