tree 43eb47b0aaf328bda952604d51943c76f968ef07
parent fa54d6fa1c2aaf941da0bc4885015df17693f8ec
author Nigel Tao <nigeltao@golang.org> 1476920063 +1100
committer Nigel Tao <nigeltao@golang.org> 1476936777 +0000

vector: change ϕ from 10 to 9.

This slight loss in quality allows us to use int32 math exclusively
throughout raster_fixed.go, instead of occasionally dropping into int64
math. The change in ϕ doesn't affect the benchmarks noticably, but
staying in int32 does. The net effect:

name                              old time/op  new time/op  delta
GlyphAlpha16Over-8                3.36µs ± 0%  2.99µs ± 0%  -10.89%         (p=0.000 n=10+9)
GlyphAlpha16Src-8                 3.26µs ± 0%  2.89µs ± 1%  -11.34%         (p=0.000 n=9+10)
GlyphAlpha32Over-8                5.20µs ± 0%  4.53µs ± 0%  -12.76%         (p=0.000 n=8+10)
GlyphAlpha32Src-8                 4.81µs ± 1%  4.14µs ± 0%  -13.91%          (p=0.000 n=9+9)
GlyphAlpha64Over-8                10.2µs ± 0%   9.0µs ± 1%  -11.99%         (p=0.000 n=9+10)
GlyphAlpha64Src-8                 8.62µs ± 0%  7.42µs ± 1%  -13.89%         (p=0.000 n=9+10)
GlyphAlpha128Over-8               24.1µs ± 0%  21.8µs ± 0%   -9.32%          (p=0.000 n=9+9)
GlyphAlpha128Src-8                17.9µs ± 0%  15.6µs ± 0%  -12.68%         (p=0.000 n=9+10)
GlyphAlpha256Over-8               70.1µs ± 0%  66.3µs ± 1%   -5.44%        (p=0.000 n=10+10)
GlyphAlpha256Src-8                45.2µs ± 1%  41.2µs ± 1%   -8.92%        (p=0.000 n=10+10)
GlyphRGBA16Over-8                 5.12µs ± 0%  4.75µs ± 0%   -7.15%         (p=0.000 n=10+9)
GlyphRGBA16Src-8                  4.57µs ± 1%  4.20µs ± 0%   -8.18%          (p=0.000 n=9+8)
GlyphRGBA32Over-8                 12.1µs ± 0%  11.4µs ± 0%   -5.50%         (p=0.000 n=10+9)
GlyphRGBA32Src-8                  10.0µs ± 0%   9.3µs ± 1%   -6.80%         (p=0.000 n=10+9)
GlyphRGBA64Over-8                 37.2µs ± 0%  36.0µs ± 0%   -3.17%          (p=0.000 n=9+8)
GlyphRGBA64Src-8                  29.0µs ± 1%  27.9µs ± 1%   -4.05%         (p=0.000 n=9+10)
GlyphRGBA128Over-8                 134µs ± 1%   131µs ± 0%   -1.85%          (p=0.000 n=9+9)
GlyphRGBA128Src-8                  100µs ± 1%    98µs ± 0%   -2.27%         (p=0.000 n=10+9)
GlyphRGBA256Over-8                 506µs ± 0%   503µs ± 0%   -0.56%         (p=0.000 n=10+8)
GlyphRGBA256Src-8                  373µs ± 0%   370µs ± 0%   -1.01%         (p=0.000 n=10+9)

Change-Id: Ie02afac6fd6fa95f090bf3fe0a5c744799ea9dc5
Reviewed-on: https://go-review.googlesource.com/31532
Reviewed-by: David Crawshaw <crawshaw@golang.org>