tree 0bb9f71f6606514ae0d291c03f0893682f5bd42e
parent dd40483534f57df206020c174cb56e2b2c258015
author msarett <msarett@google.com> 1465422233 -0700
committer Commit bot <commit-bot@chromium.org> 1465422233 -0700

Optimize color xforms with 2.2 gammas for SSE2

Because we recognize commonly used gamma tables and
parameters as 2.2f, about 98% of jpegs with color profiles
will pass through this xform (assuming the dst is also
2.2f).  Sample size is 10,322 jpegs.

I won't go crazy with performance numbers because this is
a work in progress, particularly in terms of correctness.

201295.jpg on HP z620
(300x280, most common form of sRGB profile)

Decode Time + QCMS Xform      1.28 ms
QCMS Xform Only               0.495 ms
Decode Time + Skia Opt Xform  1.01 ms
Skia Opt Xform Only           0.235 ms

Decode Time + Xform Speed-up  1.27x
Xform Only Speed-up           2.11x

FWIW, Skia xform time before these optimizations was
41.1 ms.  But we expected that code to be slow.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2046013002
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Review-Url: https://codereview.chromium.org/2046013002