remove untested blit optimization

src/opts/SkBlitRow_opts_SSE2.cpp

 /*
  * 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.
  */
 
 #include <emmintrin.h>
 #include "SkBitmapProcState_opts_SSE2.h"
 #include "SkBlitRow_opts_SSE2.h"
@@ skipping 59 matching lines @@
 void S32A_Opaque_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
                                 const SkPMColor* SK_RESTRICT src,
                                 int count, U8CPU alpha) {
     sk_msan_assert_initialized(src, src+count);
 
     SkASSERT(alpha == 255);
     if (count <= 0) {
         return;
     }
 
-#ifdef SK_USE_ACCURATE_BLENDING
-    if (count >= 4) {
-        SkASSERT(((size_t)dst & 0x03) == 0);
-        while (((size_t)dst & 0x0F) != 0) {
-            *dst = SkPMSrcOver(*src, *dst);
-            src++;
-            dst++;
-            count--;
-        }
-
-        const __m128i *s = reinterpret_cast<const __m128i*>(src);
-        __m128i *d = reinterpret_cast<__m128i*>(dst);
-        __m128i rb_mask = _mm_set1_epi32(0x00FF00FF);
-        __m128i c_128 = _mm_set1_epi16(128);  // 8 copies of 128 (16-bit)
-        __m128i c_255 = _mm_set1_epi16(255);  // 8 copies of 255 (16-bit)
-        while (count >= 4) {
-            // Load 4 pixels
-            __m128i src_pixel = _mm_loadu_si128(s);
-            __m128i dst_pixel = _mm_load_si128(d);
-
-            __m128i dst_rb = _mm_and_si128(rb_mask, dst_pixel);
-            __m128i dst_ag = _mm_srli_epi16(dst_pixel, 8);
-            // Shift alphas down to lower 8 bits of each quad.
-            __m128i alpha = _mm_srli_epi32(src_pixel, 24);
-
-            // Copy alpha to upper 3rd byte of each quad
-            alpha = _mm_or_si128(alpha, _mm_slli_epi32(alpha, 16));
-
-            // Subtract alphas from 255, to get 0..255
-            alpha = _mm_sub_epi16(c_255, alpha);
-
-            // Multiply by red and blue by src alpha.
-            dst_rb = _mm_mullo_epi16(dst_rb, alpha);
-            // Multiply by alpha and green by src alpha.
-            dst_ag = _mm_mullo_epi16(dst_ag, alpha);
-
-            // dst_rb_low = (dst_rb >> 8)
-            __m128i dst_rb_low = _mm_srli_epi16(dst_rb, 8);
-            __m128i dst_ag_low = _mm_srli_epi16(dst_ag, 8);
-
-            // dst_rb = (dst_rb + dst_rb_low + 128) >> 8
-            dst_rb = _mm_add_epi16(dst_rb, dst_rb_low);
-            dst_rb = _mm_add_epi16(dst_rb, c_128);
-            dst_rb = _mm_srli_epi16(dst_rb, 8);
-
-            // dst_ag = (dst_ag + dst_ag_low + 128) & ag_mask
-            dst_ag = _mm_add_epi16(dst_ag, dst_ag_low);
-            dst_ag = _mm_add_epi16(dst_ag, c_128);
-            dst_ag = _mm_andnot_si128(rb_mask, dst_ag);
-
-            // Combine back into RGBA.
-            dst_pixel = _mm_or_si128(dst_rb, dst_ag);
-
-            // Add result
-            __m128i result = _mm_add_epi8(src_pixel, dst_pixel);
-            _mm_store_si128(d, result);
-            s++;
-            d++;
-            count -= 4;
-        }
-        src = reinterpret_cast<const SkPMColor*>(s);
-        dst = reinterpret_cast<SkPMColor*>(d);
-    }
-
-    while (count > 0) {
-        *dst = SkPMSrcOver(*src, *dst);
-        src++;
-        dst++;
-        count--;
-    }
-#else
     int count16 = count / 16;
     __m128i* dst4 = (__m128i*)dst;
     const __m128i* src4 = (const __m128i*)src;
 
     for (int i = 0; i < count16 * 4; i += 4) {
         // Load 16 source pixels.
         __m128i s0 = _mm_loadu_si128(src4+i+0),
                 s1 = _mm_loadu_si128(src4+i+1),
                 s2 = _mm_loadu_si128(src4+i+2),
                 s3 = _mm_loadu_si128(src4+i+3);
@@ skipping 23 matching lines @@
     }
 
     // Wrap up the last <= 15 pixels.
     SkASSERT(count - (count16*16) <= 15);
     for (int i = count16*16; i < count; i++) {
         // This check is not really necessarily, but it prevents pointless autovectorization.
         if (src[i] & 0xFF000000) {
             dst[i] = SkPMSrcOver(src[i], dst[i]);
         }
     }
-#endif
 }
 
 void S32A_Blend_BlitRow32_SSE2(SkPMColor* SK_RESTRICT dst,
                                const SkPMColor* SK_RESTRICT src,
                                int count, U8CPU alpha) {
     SkASSERT(alpha <= 255);
     if (count <= 0) {
         return;
     }
 
@@ skipping 908 matching lines @@
                 uint32_t dst_expanded = SkExpand_rgb_16(*dst);
                 dst_expanded = dst_expanded * (SkAlpha255To256(255 - a) >> 3);
                 // now src and dst expanded are in g:11 r:10 x:1 b:10
                 *dst = SkCompact_rgb_16((src_expanded + dst_expanded) >> 5);
             }
             dst += 1;
             DITHER_INC_X(x);
         } while (--count != 0);
     }
 }