Add ARGBExtractAlpha_AVX2 function

source/planar_functions.cc

 /*
  *  Copyright 2011 The LibYuv Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS. All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 2684 matching lines @@
     src_stride = dst_stride = 0;
   }
   void (*ARGBExtractAlphaRow)(const uint8 *src_argb, uint8 *dst_a, int width) =
       ARGBExtractAlphaRow_C;
 #if defined(HAS_ARGBEXTRACTALPHAROW_SSE2)
   if (TestCpuFlag(kCpuHasSSE2)) {
     ARGBExtractAlphaRow = IS_ALIGNED(width, 8) ? ARGBExtractAlphaRow_SSE2
                                                : ARGBExtractAlphaRow_Any_SSE2;
   }
 #endif
+#if defined(HAS_ARGBEXTRACTALPHAROW_AVX2)
+  if (TestCpuFlag(kCpuHasAVX2)) {
+    ARGBExtractAlphaRow = IS_ALIGNED(width, 32) ? ARGBExtractAlphaRow_AVX2
+                                                : ARGBExtractAlphaRow_Any_AVX2;
+  }
+#endif
 #if defined(HAS_ARGBEXTRACTALPHAROW_NEON)
   if (TestCpuFlag(kCpuHasNEON)) {
     ARGBExtractAlphaRow = IS_ALIGNED(width, 16) ? ARGBExtractAlphaRow_NEON
                                                 : ARGBExtractAlphaRow_Any_NEON;
   }
 #endif
 
   for (int y = 0; y < height; ++y) {
     ARGBExtractAlphaRow(src_argb, dst_a, width);
     src_argb += src_stride;
@@ skipping 248 matching lines @@
     }
     free_aligned_buffer_64(rows);
   }
   return 0;
 }
 
 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace libyuv
 #endif