AVX2 SAD Optimization:

2 functions were optimized for avx2 by using full 256 bit register
In order to handle 32 elements in parallel instead of only 16 in parallel:
1. vp9_sad32x32x4d
2. vp9_sad64x64x4d

The function level gain is 66% and the user level gain is ~1%.

Change-Id: I4efbb3bc7d8bc03b64b6c98f5cd5c4a9dd3212cb

1 files changed, 167 insertions, 0 deletions

diff --git a/vp9/encoder/x86/vp9_sad4d_intrin_avx2.c b/vp9/encoder/x86/vp9_sad4d_intrin_avx2.c
new file mode 100644
index 000000000..f31b176e5
--- /dev/null
+++ b/vp9/encoder/x86/vp9_sad4d_intrin_avx2.c
@@ -0,0 +1,167 @@
+/*
+ *  Copyright (c) 2014 The WebM 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.
+ */
+#include <immintrin.h>  // AVX2
+#include "vpx/vpx_integer.h"
+
+void vp9_sad32x32x4d_avx2(uint8_t *src,
+                          int src_stride,
+                          uint8_t *ref[4],
+                          int ref_stride,
+                          unsigned int res[4]) {
+  __m256i src_reg, ref0_reg, ref1_reg, ref2_reg, ref3_reg;
+  __m256i sum_ref0, sum_ref1, sum_ref2, sum_ref3;
+  __m256i sum_mlow, sum_mhigh;
+  int i;
+  uint8_t *ref0, *ref1, *ref2, *ref3;
+
+  ref0 = ref[0];
+  ref1 = ref[1];
+  ref2 = ref[2];
+  ref3 = ref[3];
+  sum_ref0 = _mm256_set1_epi16(0);
+  sum_ref1 = _mm256_set1_epi16(0);
+  sum_ref2 = _mm256_set1_epi16(0);
+  sum_ref3 = _mm256_set1_epi16(0);
+  for (i = 0; i < 32 ; i++) {
+    // load src and all refs
+    src_reg = _mm256_load_si256((__m256i *)(src));
+    ref0_reg = _mm256_loadu_si256((__m256i *) (ref0));
+    ref1_reg = _mm256_loadu_si256((__m256i *) (ref1));
+    ref2_reg = _mm256_loadu_si256((__m256i *) (ref2));
+    ref3_reg = _mm256_loadu_si256((__m256i *) (ref3));
+    // sum of the absolute differences between every ref-i to src
+    ref0_reg = _mm256_sad_epu8(ref0_reg, src_reg);
+    ref1_reg = _mm256_sad_epu8(ref1_reg, src_reg);
+    ref2_reg = _mm256_sad_epu8(ref2_reg, src_reg);
+    ref3_reg = _mm256_sad_epu8(ref3_reg, src_reg);
+    // sum every ref-i
+    sum_ref0 = _mm256_add_epi32(sum_ref0, ref0_reg);
+    sum_ref1 = _mm256_add_epi32(sum_ref1, ref1_reg);
+    sum_ref2 = _mm256_add_epi32(sum_ref2, ref2_reg);
+    sum_ref3 = _mm256_add_epi32(sum_ref3, ref3_reg);
+
+    src+= src_stride;
+    ref0+= ref_stride;
+    ref1+= ref_stride;
+    ref2+= ref_stride;
+    ref3+= ref_stride;
+  }
+  {
+    __m128i sum;
+    // in sum_ref-i the result is saved in the first 4 bytes
+    // the other 4 bytes are zeroed.
+    // sum_ref1 and sum_ref3 are shifted left by 4 bytes
+    sum_ref1 = _mm256_slli_si256(sum_ref1, 4);
+    sum_ref3 = _mm256_slli_si256(sum_ref3, 4);
+
+    // merge sum_ref0 and sum_ref1 also sum_ref2 and sum_ref3
+    sum_ref0 = _mm256_or_si256(sum_ref0, sum_ref1);
+    sum_ref2 = _mm256_or_si256(sum_ref2, sum_ref3);
+
+    // merge every 64 bit from each sum_ref-i
+    sum_mlow = _mm256_unpacklo_epi64(sum_ref0, sum_ref2);
+    sum_mhigh = _mm256_unpackhi_epi64(sum_ref0, sum_ref2);
+
+    // add the low 64 bit to the high 64 bit
+    sum_mlow = _mm256_add_epi32(sum_mlow, sum_mhigh);
+
+    // add the low 128 bit to the high 128 bit
+    sum = _mm_add_epi32(_mm256_castsi256_si128(sum_mlow),
+                        _mm256_extractf128_si256(sum_mlow, 1));
+
+    _mm_storeu_si128((__m128i *)(res), sum);
+  }
+}
+
+void vp9_sad64x64x4d_avx2(uint8_t *src,
+                          int src_stride,
+                          uint8_t *ref[4],
+                          int ref_stride,
+                          unsigned int res[4]) {
+  __m256i src_reg, srcnext_reg, ref0_reg, ref0next_reg;
+  __m256i ref1_reg, ref1next_reg, ref2_reg, ref2next_reg;
+  __m256i ref3_reg, ref3next_reg;
+  __m256i sum_ref0, sum_ref1, sum_ref2, sum_ref3;
+  __m256i sum_mlow, sum_mhigh;
+  int i;
+  uint8_t *ref0, *ref1, *ref2, *ref3;
+
+  ref0 = ref[0];
+  ref1 = ref[1];
+  ref2 = ref[2];
+  ref3 = ref[3];
+  sum_ref0 = _mm256_set1_epi16(0);
+  sum_ref1 = _mm256_set1_epi16(0);
+  sum_ref2 = _mm256_set1_epi16(0);
+  sum_ref3 = _mm256_set1_epi16(0);
+  for (i = 0; i < 64 ; i++) {
+    // load 64 bytes from src and all refs
+    src_reg = _mm256_load_si256((__m256i *)(src));
+    srcnext_reg = _mm256_load_si256((__m256i *)(src + 32));
+    ref0_reg = _mm256_loadu_si256((__m256i *) (ref0));
+    ref0next_reg = _mm256_loadu_si256((__m256i *) (ref0 + 32));
+    ref1_reg = _mm256_loadu_si256((__m256i *) (ref1));
+    ref1next_reg = _mm256_loadu_si256((__m256i *) (ref1 + 32));
+    ref2_reg = _mm256_loadu_si256((__m256i *) (ref2));
+    ref2next_reg = _mm256_loadu_si256((__m256i *) (ref2 + 32));
+    ref3_reg = _mm256_loadu_si256((__m256i *) (ref3));
+    ref3next_reg = _mm256_loadu_si256((__m256i *) (ref3 + 32));
+    // sum of the absolute differences between every ref-i to src
+    ref0_reg = _mm256_sad_epu8(ref0_reg, src_reg);
+    ref1_reg = _mm256_sad_epu8(ref1_reg, src_reg);
+    ref2_reg = _mm256_sad_epu8(ref2_reg, src_reg);
+    ref3_reg = _mm256_sad_epu8(ref3_reg, src_reg);
+    ref0next_reg = _mm256_sad_epu8(ref0next_reg, srcnext_reg);
+    ref1next_reg = _mm256_sad_epu8(ref1next_reg, srcnext_reg);
+    ref2next_reg = _mm256_sad_epu8(ref2next_reg, srcnext_reg);
+    ref3next_reg = _mm256_sad_epu8(ref3next_reg, srcnext_reg);
+
+    // sum every ref-i
+    sum_ref0 = _mm256_add_epi32(sum_ref0, ref0_reg);
+    sum_ref1 = _mm256_add_epi32(sum_ref1, ref1_reg);
+    sum_ref2 = _mm256_add_epi32(sum_ref2, ref2_reg);
+    sum_ref3 = _mm256_add_epi32(sum_ref3, ref3_reg);
+    sum_ref0 = _mm256_add_epi32(sum_ref0, ref0next_reg);
+    sum_ref1 = _mm256_add_epi32(sum_ref1, ref1next_reg);
+    sum_ref2 = _mm256_add_epi32(sum_ref2, ref2next_reg);
+    sum_ref3 = _mm256_add_epi32(sum_ref3, ref3next_reg);
+    src+= src_stride;
+    ref0+= ref_stride;
+    ref1+= ref_stride;
+    ref2+= ref_stride;
+    ref3+= ref_stride;
+  }
+  {
+    __m128i sum;
+
+    // in sum_ref-i the result is saved in the first 4 bytes
+    // the other 4 bytes are zeroed.
+    // sum_ref1 and sum_ref3 are shifted left by 4 bytes
+    sum_ref1 = _mm256_slli_si256(sum_ref1, 4);
+    sum_ref3 = _mm256_slli_si256(sum_ref3, 4);
+
+    // merge sum_ref0 and sum_ref1 also sum_ref2 and sum_ref3
+    sum_ref0 = _mm256_or_si256(sum_ref0, sum_ref1);
+    sum_ref2 = _mm256_or_si256(sum_ref2, sum_ref3);
+
+    // merge every 64 bit from each sum_ref-i
+    sum_mlow = _mm256_unpacklo_epi64(sum_ref0, sum_ref2);
+    sum_mhigh = _mm256_unpackhi_epi64(sum_ref0, sum_ref2);
+
+    // add the low 64 bit to the high 64 bit
+    sum_mlow = _mm256_add_epi32(sum_mlow, sum_mhigh);
+
+    // add the low 128 bit to the high 128 bit
+    sum = _mm_add_epi32(_mm256_castsi256_si128(sum_mlow),
+                        _mm256_extractf128_si256(sum_mlow, 1));
+
+    _mm_storeu_si128((__m128i *)(res), sum);
+  }
+}