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Optimize SkAlphaMulQ_SSE2

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These two mask clear are useless, because _mm_srli_epi16 fills high byte
of each word with 0.

BUG=skia:

Review URL: https://codereview.chromium.org/724333003
This commit is contained in:
qiankun.miao 2014-11-14 08:23:53 -08:00 committed by Commit bot
parent c7e55e410c
commit f04713d9c8
1 changed files with 5 additions and 2 deletions
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7
src/opts/SkColor_opts_SSE2.h
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@ -10,6 +10,8 @@
#include <emmintrin.h>
#define ASSERT_EQ(a,b) SkASSERT(0xffff == _mm_movemask_epi8(_mm_cmpeq_epi8((a), (b))))
// Because no _mm_mul_epi32() in SSE2, we emulate it here.
// Multiplies 4 32-bit integers from a by 4 32-bit intergers from b.
// The 4 multiplication results should be represented within 32-bit
@ -52,11 +54,11 @@ static inline __m128i SkAlphaMulQ_SSE2(const __m128i& c, const __m128i& scale) {
// uint32_t ag = ((c >> 8) & mask) * scale
__m128i ag = _mm_srli_epi16(c, 8);
ag = _mm_and_si128(ag, mask);
ASSERT_EQ(ag, _mm_and_si128(mask, ag)); // ag = _mm_srli_epi16(c, 8) did this for us.
ag = _mm_mullo_epi16(ag, s);
// (rb & mask) | (ag & ~mask)
rb = _mm_and_si128(mask, rb);
ASSERT_EQ(rb, _mm_and_si128(mask, rb)); // rb = _mm_srli_epi16(rb, 8) did this for us.
ag = _mm_andnot_si128(mask, ag);
return _mm_or_si128(rb, ag);
}
@ -183,4 +185,5 @@ static inline __m128i SkPixel32ToPixel16_ToU16_SSE2(const __m128i& src_pixel1,
return d_pixel;
}
#undef ASSERT_EQ
#endif // SkColor_opts_SSE2_DEFINED