Kyle Siefring ae35425ae6 Optimize convolve8 SSSE3 and AVX2 intrinsics
Changed the intrinsics to perform summation similiar to the way the assembly does.

The new code diverges from the assembly by preferring unsaturated additions.

Results for haswell

SSSE3
Horiz/Vert  Size  Speedup
Horiz       x4    ~32%
Horiz       x8    ~6%
Vert        x8    ~4%

AVX2
Horiz/Vert  Size  Speedup
Horiz       x16   ~16%
Vert        x16   ~14%

BUG=webm:1471

Change-Id: I7ad98ea688c904b1ba324adf8eb977873c8b8668
2017-10-24 10:39:48 -04:00
..
2017-10-03 20:02:21 +00:00
2016-07-25 14:14:19 -07:00
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2017-10-03 20:02:21 +00:00
2016-07-25 14:14:19 -07:00
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2016-07-25 14:14:19 -07:00
2015-05-06 16:58:20 -07:00
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2015-08-07 16:44:44 -07:00