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Improve SSE2 code for Blending BlitRow functions, producing 10% speedup.

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Courtesy of Evan Nier.

http://codereview.appspot.com/5518045/



git-svn-id: http://skia.googlecode.com/svn/trunk@3273 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
tomhudson@google.com 2012-02-28 16:15:26 +00:00
parent 5efaf26893
commit 98a5b420aa
1 changed files with 56 additions and 26 deletions
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82
src/opts/SkBlitRow_opts_SSE2.cpp
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@ -1,6 +1,5 @@
/*
* Copyright 2009 The Android Open Source Project
* Copyright 2012 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
@ -39,34 +38,54 @@ void S32_Blend_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
const __m128i *s = reinterpret_cast<const __m128i*>(src);
__m128i *d = reinterpret_cast<__m128i*>(dst);
__m128i rb_mask = _mm_set1_epi32(0x00FF00FF);
__m128i src_scale_wide = _mm_set1_epi16(src_scale);
__m128i dst_scale_wide = _mm_set1_epi16(dst_scale);
__m128i ag_mask = _mm_set1_epi32(0xFF00FF00);
// Move scale factors to upper byte of word
__m128i src_scale_wide = _mm_set1_epi16(src_scale << 8);
__m128i dst_scale_wide = _mm_set1_epi16(dst_scale << 8);
while (count >= 4) {
// Load 4 pixels each of src and dest.
__m128i src_pixel = _mm_loadu_si128(s);
__m128i dst_pixel = _mm_load_si128(d);
// Interleave Atom port 0/1 operations based on the execution port
// constraints that multiply can only be executed on port 0 (while
// boolean operations can be executed on either port 0 or port 1)
// because GCC currently doesn't do a good job scheduling
// instructions based on these constraints.
// Get red and blue pixels into lower byte of each word.
__m128i dst_rb = _mm_and_si128(rb_mask, dst_pixel);
// (0, r, 0, b, 0, r, 0, b, 0, r, 0, b, 0, r, 0, b)
__m128i src_rb = _mm_and_si128(rb_mask, src_pixel);
// Get alpha and green into lower byte of each word.
__m128i dst_ag = _mm_srli_epi16(dst_pixel, 8);
__m128i src_ag = _mm_srli_epi16(src_pixel, 8);
// Multiply by scale.
// (4 x (0, rs.h, 0, bs.h))
// where rs.h stands for the higher byte of r * scale, and
// bs.h the higher byte of b * scale.
src_rb = _mm_mulhi_epu16(src_rb, src_scale_wide);
// Get alpha and green pixels into higher byte of each word.
// (a, 0, g, 0, a, 0, g, 0, a, 0, g, 0, a, 0, g, 0)
__m128i src_ag = _mm_and_si128(ag_mask, src_pixel);
// Multiply by scale.
src_rb = _mm_mullo_epi16(src_rb, src_scale_wide);
src_ag = _mm_mullo_epi16(src_ag, src_scale_wide);
dst_rb = _mm_mullo_epi16(dst_rb, dst_scale_wide);
dst_ag = _mm_mullo_epi16(dst_ag, dst_scale_wide);
// (4 x (as.h, as.l, gs.h, gs.l))
src_ag = _mm_mulhi_epu16(src_ag, src_scale_wide);
// Divide by 256.
src_rb = _mm_srli_epi16(src_rb, 8);
dst_rb = _mm_srli_epi16(dst_rb, 8);
src_ag = _mm_andnot_si128(rb_mask, src_ag);
dst_ag = _mm_andnot_si128(rb_mask, dst_ag);
// Clear the lower byte of the a*scale and g*scale results
// (4 x (as.h, 0, gs.h, 0))
src_ag = _mm_and_si128(src_ag, ag_mask);
// Operations the destination pixels are the same as on the
// source pixels. See the comments above.
__m128i dst_rb = _mm_and_si128(rb_mask, dst_pixel);
dst_rb = _mm_mulhi_epu16(dst_rb, dst_scale_wide);
__m128i dst_ag = _mm_and_si128(ag_mask, dst_pixel);
dst_ag = _mm_mulhi_epu16(dst_ag, dst_scale_wide);
dst_ag = _mm_and_si128(dst_ag, ag_mask);
// Combine back into RGBA.
// (4 x (as.h, rs.h, gs.h, bs.h))
src_pixel = _mm_or_si128(src_rb, src_ag);
dst_pixel = _mm_or_si128(dst_rb, dst_ag);
@ -234,7 +253,7 @@ void S32A_Blend_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
const __m128i *s = reinterpret_cast<const __m128i*>(src);
__m128i *d = reinterpret_cast<__m128i*>(dst);
__m128i src_scale_wide = _mm_set1_epi16(src_scale);
__m128i src_scale_wide = _mm_set1_epi16(src_scale << 8);
__m128i rb_mask = _mm_set1_epi32(0x00FF00FF);
__m128i c_256 = _mm_set1_epi16(256); // 8 copies of 256 (16-bit)
while (count >= 4) {
@ -251,14 +270,17 @@ void S32A_Blend_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
__m128i src_ag = _mm_srli_epi16(src_pixel, 8);
// Put per-pixel alpha in low byte of each word.
// After the following two statements, the dst_alpha looks like
// (0, a0, 0, a0, 0, a1, 0, a1, 0, a2, 0, a2, 0, a3, 0, a3)
__m128i dst_alpha = _mm_shufflehi_epi16(src_ag, 0xF5);
dst_alpha = _mm_shufflelo_epi16(dst_alpha, 0xF5);
// dst_alpha = dst_alpha * src_scale
dst_alpha = _mm_mullo_epi16(dst_alpha, src_scale_wide);
// Divide by 256.
dst_alpha = _mm_srli_epi16(dst_alpha, 8);
// Because src_scales are in the higher byte of each word and
// we use mulhi here, the resulting alpha values are already
// in the right place and don't need to be divided by 256.
// (0, sa0, 0, sa0, 0, sa1, 0, sa1, 0, sa2, 0, sa2, 0, sa3, 0, sa3)
dst_alpha = _mm_mulhi_epu16(dst_alpha, src_scale_wide);
// Subtract alphas from 256, to get 1..256
dst_alpha = _mm_sub_epi16(c_256, dst_alpha);
@ -269,17 +291,25 @@ void S32A_Blend_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
dst_ag = _mm_mullo_epi16(dst_ag, dst_alpha);
// Multiply red and blue by global alpha.
src_rb = _mm_mullo_epi16(src_rb, src_scale_wide);
// (4 x (0, rs.h, 0, bs.h))
// where rs.h stands for the higher byte of r * src_scale,
// and bs.h the higher byte of b * src_scale.
// Again, because we use mulhi, the resuling red and blue
// values are already in the right place and don't need to
// be divided by 256.
src_rb = _mm_mulhi_epu16(src_rb, src_scale_wide);
// Multiply alpha and green by global alpha.
src_ag = _mm_mullo_epi16(src_ag, src_scale_wide);
// (4 x (0, as.h, 0, gs.h))
src_ag = _mm_mulhi_epu16(src_ag, src_scale_wide);
// Divide by 256.
dst_rb = _mm_srli_epi16(dst_rb, 8);
src_rb = _mm_srli_epi16(src_rb, 8);
// Mask out low bits (goodies already in the right place; no need to divide)
dst_ag = _mm_andnot_si128(rb_mask, dst_ag);
src_ag = _mm_andnot_si128(rb_mask, src_ag);
// Shift alpha and green to higher byte of each word.
// (4 x (as.h, 0, gs.h, 0))
src_ag = _mm_slli_epi16(src_ag, 8);
// Combine back into RGBA.
dst_pixel = _mm_or_si128(dst_rb, dst_ag);