AVX2 Variance Optimization

Optimizing the variance functions: vp9_variance16x16, vp9_variance32x32,
vp9_variance64x64, vp9_variance32x16, vp9_variance64x32,
vp9_mse16x16 by migrating to AVX2
some of the functions were optimized by processing 32 elements instead of 16.
some of the functions were optimized by processing 2 loop strides of 16
elements in a single 256 bit register
This optimization gives between 2.4% - 2.7% user level performance gain
and 42% function level gain.

Change-Id: I265ae08a2b0196057a224a86450153ef3aebd85d

4 files changed, 378 insertions, 6 deletions

diff --git a/vp9/common/vp9_rtcd_defs.sh b/vp9/common/vp9_rtcd_defs.sh
index 3025ed42c..26fd7fb94 100644
--- a/vp9/common/vp9_rtcd_defs.sh
+++ b/vp9/common/vp9_rtcd_defs.sh
@@ -343,25 +343,25 @@ if [ "$CONFIG_VP9_ENCODER" = "yes" ]; then
 
 # variance
 prototype unsigned int vp9_variance32x16 "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse"
-specialize vp9_variance32x16 $sse2_x86inc
+specialize vp9_variance32x16 $sse2_x86inc $avx2_x86inc
 
 prototype unsigned int vp9_variance16x32 "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse"
 specialize vp9_variance16x32 $sse2_x86inc
 
 prototype unsigned int vp9_variance64x32 "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse"
-specialize vp9_variance64x32 $sse2_x86inc
+specialize vp9_variance64x32 $sse2_x86inc $avx2_x86inc
 
 prototype unsigned int vp9_variance32x64 "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse"
 specialize vp9_variance32x64 $sse2_x86inc
 
 prototype unsigned int vp9_variance32x32 "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse"
-specialize vp9_variance32x32 $sse2_x86inc
+specialize vp9_variance32x32 $sse2_x86inc $avx2_x86inc
 
 prototype unsigned int vp9_variance64x64 "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse"
-specialize vp9_variance64x64 $sse2_x86inc
+specialize vp9_variance64x64 $sse2_x86inc $avx2_x86inc
 
 prototype unsigned int vp9_variance16x16 "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse"
-specialize vp9_variance16x16 mmx $sse2_x86inc
+specialize vp9_variance16x16 mmx $sse2_x86inc $avx2_x86inc
 
 prototype unsigned int vp9_variance16x8 "const uint8_t *src_ptr, int source_stride, const uint8_t *ref_ptr, int ref_stride, unsigned int *sse"
 specialize vp9_variance16x8 mmx $sse2_x86inc
@@ -662,7 +662,7 @@ specialize vp9_sad4x4x4d sse
 #specialize vp9_sub_pixel_mse16x16 sse2 mmx
 
 prototype unsigned int vp9_mse16x16 "const uint8_t *src_ptr, int  source_stride, const uint8_t *ref_ptr, int  recon_stride, unsigned int *sse"
-specialize vp9_mse16x16 mmx $sse2_x86inc
+specialize vp9_mse16x16 mmx $sse2_x86inc $avx2_x86inc
 
 prototype unsigned int vp9_mse8x16 "const uint8_t *src_ptr, int  source_stride, const uint8_t *ref_ptr, int  recon_stride, unsigned int *sse"
 specialize vp9_mse8x16
diff --git a/vp9/encoder/x86/vp9_variance_avx2.c b/vp9/encoder/x86/vp9_variance_avx2.c
new file mode 100644
index 000000000..c9b90d52d
--- /dev/null
+++ b/vp9/encoder/x86/vp9_variance_avx2.c
@@ -0,0 +1,157 @@
+/*
+ *  Copyright (c) 2012 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 "./vpx_config.h"
+
+#include "vp9/encoder/vp9_variance.h"
+#include "vp9/common/vp9_pragmas.h"
+#include "vpx_ports/mem.h"
+
+typedef void (*get_var_avx2) (
+  const unsigned char *src_ptr,
+  int source_stride,
+  const unsigned char *ref_ptr,
+  int recon_stride,
+  unsigned int *SSE,
+  int *Sum
+);
+
+void vp9_get16x16var_avx2
+(
+  const unsigned char *src_ptr,
+  int source_stride,
+  const unsigned char *ref_ptr,
+  int recon_stride,
+  unsigned int *SSE,
+  int *Sum
+);
+
+void vp9_get32x32var_avx2
+(
+  const unsigned char *src_ptr,
+  int source_stride,
+  const unsigned char *ref_ptr,
+  int recon_stride,
+  unsigned int *SSE,
+  int *Sum
+);
+
+static void variance_avx2(const unsigned char *src_ptr, int  source_stride,
+                        const unsigned char *ref_ptr, int  recon_stride,
+                        int  w, int  h, unsigned int *sse, int *sum,
+                        get_var_avx2 var_fn, int block_size) {
+  unsigned int sse0;
+  int sum0;
+  int i, j;
+
+  *sse = 0;
+  *sum = 0;
+
+  for (i = 0; i < h; i += 16) {
+    for (j = 0; j < w; j += block_size) {
+      // processing 16 rows horizontally each call
+      var_fn(src_ptr + source_stride * i + j, source_stride,
+             ref_ptr + recon_stride * i + j, recon_stride, &sse0, &sum0);
+      *sse += sse0;
+      *sum += sum0;
+    }
+  }
+}
+
+unsigned int vp9_variance16x16_avx2
+(
+  const unsigned char *src_ptr,
+  int  source_stride,
+  const unsigned char *ref_ptr,
+  int  recon_stride,
+  unsigned int *sse) {
+  unsigned int var;
+  int avg;
+
+  variance_avx2(src_ptr, source_stride, ref_ptr, recon_stride, 16, 16,
+                &var, &avg, vp9_get16x16var_avx2, 16);
+  *sse = var;
+  return (var - (((unsigned int)avg * avg) >> 8));
+}
+
+unsigned int vp9_mse16x16_avx2(
+  const unsigned char *src_ptr,
+  int  source_stride,
+  const unsigned char *ref_ptr,
+  int  recon_stride,
+  unsigned int *sse) {
+  unsigned int sse0;
+  int sum0;
+  vp9_get16x16var_avx2(src_ptr, source_stride, ref_ptr, recon_stride, &sse0,
+                       &sum0);
+  *sse = sse0;
+  return sse0;
+}
+
+unsigned int vp9_variance32x32_avx2(const uint8_t *src_ptr,
+                                    int  source_stride,
+                                    const uint8_t *ref_ptr,
+                                    int  recon_stride,
+                                    unsigned int *sse) {
+  unsigned int var;
+  int avg;
+
+  // processing 32 elements vertically in parallel
+  variance_avx2(src_ptr, source_stride, ref_ptr, recon_stride, 32, 32,
+                &var, &avg, vp9_get32x32var_avx2, 32);
+  *sse = var;
+  return (var - (((int64_t)avg * avg) >> 10));
+}
+
+unsigned int vp9_variance32x16_avx2(const uint8_t *src_ptr,
+                                    int  source_stride,
+                                    const uint8_t *ref_ptr,
+                                    int  recon_stride,
+                                    unsigned int *sse) {
+  unsigned int var;
+  int avg;
+
+  // processing 32 elements vertically in parallel
+  variance_avx2(src_ptr, source_stride, ref_ptr, recon_stride, 32, 16,
+                &var, &avg, vp9_get32x32var_avx2, 32);
+  *sse = var;
+  return (var - (((int64_t)avg * avg) >> 9));
+}
+
+
+unsigned int vp9_variance64x64_avx2(const uint8_t *src_ptr,
+                                    int  source_stride,
+                                    const uint8_t *ref_ptr,
+                                    int  recon_stride,
+                                    unsigned int *sse) {
+  unsigned int var;
+  int avg;
+
+  // processing 32 elements vertically in parallel
+  variance_avx2(src_ptr, source_stride, ref_ptr, recon_stride, 64, 64,
+                &var, &avg, vp9_get32x32var_avx2, 32);
+  *sse = var;
+  return (var - (((int64_t)avg * avg) >> 12));
+}
+
+unsigned int vp9_variance64x32_avx2(const uint8_t *src_ptr,
+                                    int  source_stride,
+                                    const uint8_t *ref_ptr,
+                                    int  recon_stride,
+                                    unsigned int *sse) {
+  unsigned int var;
+  int avg;
+
+  // processing 32 elements vertically in parallel
+  variance_avx2(src_ptr, source_stride, ref_ptr, recon_stride, 64, 32,
+                &var, &avg, vp9_get32x32var_avx2, 32);
+
+  *sse = var;
+  return (var - (((int64_t)avg * avg) >> 11));
+}
diff --git a/vp9/encoder/x86/vp9_variance_impl_intrin_avx2.c b/vp9/encoder/x86/vp9_variance_impl_intrin_avx2.c
new file mode 100644
index 000000000..f9923280a
--- /dev/null
+++ b/vp9/encoder/x86/vp9_variance_impl_intrin_avx2.c
@@ -0,0 +1,213 @@
+/*
+ *  Copyright (c) 2012 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
+
+void vp9_get16x16var_avx2(const unsigned char *src_ptr,
+                          int source_stride,
+                          const unsigned char *ref_ptr,
+                          int recon_stride,
+                          unsigned int *SSE,
+                          int *Sum) {
+    __m256i src, src_expand_low, src_expand_high, ref, ref_expand_low;
+    __m256i ref_expand_high, madd_low, madd_high;
+    unsigned int i, src_2strides, ref_2strides;
+    __m256i zero_reg = _mm256_set1_epi16(0);
+    __m256i sum_ref_src = _mm256_set1_epi16(0);
+    __m256i madd_ref_src = _mm256_set1_epi16(0);
+
+    // processing two strides in a 256 bit register reducing the number
+    // of loop stride by half (comparing to the sse2 code)
+    src_2strides = source_stride << 1;
+    ref_2strides = recon_stride << 1;
+    for (i = 0; i < 8; i++) {
+        src = _mm256_castsi128_si256(
+              _mm_loadu_si128((__m128i const *) (src_ptr)));
+        src = _mm256_inserti128_si256(src,
+              _mm_loadu_si128((__m128i const *)(src_ptr+source_stride)), 1);
+
+        ref =_mm256_castsi128_si256(
+             _mm_loadu_si128((__m128i const *) (ref_ptr)));
+        ref = _mm256_inserti128_si256(ref,
+              _mm_loadu_si128((__m128i const *)(ref_ptr+recon_stride)), 1);
+
+        // expanding to 16 bit each lane
+        src_expand_low = _mm256_unpacklo_epi8(src, zero_reg);
+        src_expand_high = _mm256_unpackhi_epi8(src, zero_reg);
+
+        ref_expand_low = _mm256_unpacklo_epi8(ref, zero_reg);
+        ref_expand_high = _mm256_unpackhi_epi8(ref, zero_reg);
+
+        // src-ref
+        src_expand_low = _mm256_sub_epi16(src_expand_low, ref_expand_low);
+        src_expand_high = _mm256_sub_epi16(src_expand_high, ref_expand_high);
+
+        // madd low (src - ref)
+        madd_low = _mm256_madd_epi16(src_expand_low, src_expand_low);
+
+        // add high to low
+        src_expand_low = _mm256_add_epi16(src_expand_low, src_expand_high);
+
+        // madd high (src - ref)
+        madd_high = _mm256_madd_epi16(src_expand_high, src_expand_high);
+
+        sum_ref_src = _mm256_add_epi16(sum_ref_src, src_expand_low);
+
+        // add high to low
+        madd_ref_src = _mm256_add_epi32(madd_ref_src,
+                       _mm256_add_epi32(madd_low, madd_high));
+
+        src_ptr+= src_2strides;
+        ref_ptr+= ref_2strides;
+    }
+
+    {
+        __m128i sum_res, madd_res;
+        __m128i expand_sum_low, expand_sum_high, expand_sum;
+        __m128i expand_madd_low, expand_madd_high, expand_madd;
+        __m128i ex_expand_sum_low, ex_expand_sum_high, ex_expand_sum;
+
+        // extract the low lane and add it to the high lane
+        sum_res = _mm_add_epi16(_mm256_castsi256_si128(sum_ref_src),
+                                _mm256_extractf128_si256(sum_ref_src, 1));
+
+        madd_res = _mm_add_epi32(_mm256_castsi256_si128(madd_ref_src),
+                                 _mm256_extractf128_si256(madd_ref_src, 1));
+
+        // padding each 2 bytes with another 2 zeroed bytes
+        expand_sum_low = _mm_unpacklo_epi16(_mm256_castsi256_si128(zero_reg),
+                                            sum_res);
+        expand_sum_high = _mm_unpackhi_epi16(_mm256_castsi256_si128(zero_reg),
+                                             sum_res);
+
+        // shifting the sign 16 bits right
+        expand_sum_low = _mm_srai_epi32(expand_sum_low, 16);
+        expand_sum_high = _mm_srai_epi32(expand_sum_high, 16);
+
+        expand_sum = _mm_add_epi32(expand_sum_low, expand_sum_high);
+
+        // expand each 32 bits of the madd result to 64 bits
+        expand_madd_low = _mm_unpacklo_epi32(madd_res,
+                          _mm256_castsi256_si128(zero_reg));
+        expand_madd_high = _mm_unpackhi_epi32(madd_res,
+                           _mm256_castsi256_si128(zero_reg));
+
+        expand_madd = _mm_add_epi32(expand_madd_low, expand_madd_high);
+
+        ex_expand_sum_low = _mm_unpacklo_epi32(expand_sum,
+                            _mm256_castsi256_si128(zero_reg));
+        ex_expand_sum_high = _mm_unpackhi_epi32(expand_sum,
+                             _mm256_castsi256_si128(zero_reg));
+
+        ex_expand_sum = _mm_add_epi32(ex_expand_sum_low, ex_expand_sum_high);
+
+        // shift 8 bytes eight
+        madd_res = _mm_srli_si128(expand_madd, 8);
+        sum_res = _mm_srli_si128(ex_expand_sum, 8);
+
+        madd_res = _mm_add_epi32(madd_res, expand_madd);
+        sum_res = _mm_add_epi32(sum_res, ex_expand_sum);
+
+        *((int*)SSE)= _mm_cvtsi128_si32(madd_res);
+
+        *((int*)Sum)= _mm_cvtsi128_si32(sum_res);
+    }
+}
+
+void vp9_get32x32var_avx2(const unsigned char *src_ptr,
+                          int source_stride,
+                          const unsigned char *ref_ptr,
+                          int recon_stride,
+                          unsigned int *SSE,
+                          int *Sum) {
+    __m256i src, src_expand_low, src_expand_high, ref, ref_expand_low;
+    __m256i ref_expand_high, madd_low, madd_high;
+    unsigned int i;
+    __m256i zero_reg = _mm256_set1_epi16(0);
+    __m256i sum_ref_src = _mm256_set1_epi16(0);
+    __m256i madd_ref_src = _mm256_set1_epi16(0);
+
+    // processing 32 elements in parallel
+    for (i = 0; i < 16; i++) {
+       src = _mm256_loadu_si256((__m256i const *) (src_ptr));
+
+       ref = _mm256_loadu_si256((__m256i const *) (ref_ptr));
+
+       // expanding to 16 bit each lane
+       src_expand_low = _mm256_unpacklo_epi8(src, zero_reg);
+       src_expand_high = _mm256_unpackhi_epi8(src, zero_reg);
+
+       ref_expand_low = _mm256_unpacklo_epi8(ref, zero_reg);
+       ref_expand_high = _mm256_unpackhi_epi8(ref, zero_reg);
+
+       // src-ref
+       src_expand_low = _mm256_sub_epi16(src_expand_low, ref_expand_low);
+       src_expand_high = _mm256_sub_epi16(src_expand_high, ref_expand_high);
+
+       // madd low (src - ref)
+       madd_low = _mm256_madd_epi16(src_expand_low, src_expand_low);
+
+       // add high to low
+       src_expand_low = _mm256_add_epi16(src_expand_low, src_expand_high);
+
+       // madd high (src - ref)
+       madd_high = _mm256_madd_epi16(src_expand_high, src_expand_high);
+
+       sum_ref_src = _mm256_add_epi16(sum_ref_src, src_expand_low);
+
+       // add high to low
+       madd_ref_src = _mm256_add_epi32(madd_ref_src,
+                      _mm256_add_epi32(madd_low, madd_high));
+
+       src_ptr+= source_stride;
+       ref_ptr+= recon_stride;
+    }
+
+    {
+      __m256i expand_sum_low, expand_sum_high, expand_sum;
+      __m256i expand_madd_low, expand_madd_high, expand_madd;
+      __m256i ex_expand_sum_low, ex_expand_sum_high, ex_expand_sum;
+
+      // padding each 2 bytes with another 2 zeroed bytes
+      expand_sum_low = _mm256_unpacklo_epi16(zero_reg, sum_ref_src);
+      expand_sum_high = _mm256_unpackhi_epi16(zero_reg, sum_ref_src);
+
+      // shifting the sign 16 bits right
+      expand_sum_low = _mm256_srai_epi32(expand_sum_low, 16);
+      expand_sum_high = _mm256_srai_epi32(expand_sum_high, 16);
+
+      expand_sum = _mm256_add_epi32(expand_sum_low, expand_sum_high);
+
+      // expand each 32 bits of the madd result to 64 bits
+      expand_madd_low = _mm256_unpacklo_epi32(madd_ref_src, zero_reg);
+      expand_madd_high = _mm256_unpackhi_epi32(madd_ref_src, zero_reg);
+
+      expand_madd = _mm256_add_epi32(expand_madd_low, expand_madd_high);
+
+      ex_expand_sum_low = _mm256_unpacklo_epi32(expand_sum, zero_reg);
+      ex_expand_sum_high = _mm256_unpackhi_epi32(expand_sum, zero_reg);
+
+      ex_expand_sum = _mm256_add_epi32(ex_expand_sum_low, ex_expand_sum_high);
+
+      // shift 8 bytes eight
+      madd_ref_src = _mm256_srli_si256(expand_madd, 8);
+      sum_ref_src = _mm256_srli_si256(ex_expand_sum, 8);
+
+      madd_ref_src = _mm256_add_epi32(madd_ref_src, expand_madd);
+      sum_ref_src = _mm256_add_epi32(sum_ref_src, ex_expand_sum);
+
+      // extract the low lane and the high lane and add the results
+      *((int*)SSE)= _mm_cvtsi128_si32(_mm256_castsi256_si128(madd_ref_src)) +
+      _mm_cvtsi128_si32(_mm256_extractf128_si256(madd_ref_src, 1));
+
+      *((int*)Sum)= _mm_cvtsi128_si32(_mm256_castsi256_si128(sum_ref_src)) +
+      _mm_cvtsi128_si32(_mm256_extractf128_si256(sum_ref_src, 1));
+    }
+}
diff --git a/vp9/vp9cx.mk b/vp9/vp9cx.mk
index 9114a30e7..0d79346fe 100644
--- a/vp9/vp9cx.mk
+++ b/vp9/vp9cx.mk
@@ -81,6 +81,7 @@ VP9_CX_SRCS-$(HAVE_MMX) += encoder/x86/vp9_variance_mmx.c
 VP9_CX_SRCS-$(HAVE_MMX) += encoder/x86/vp9_variance_impl_mmx.asm
 VP9_CX_SRCS-$(HAVE_MMX) += encoder/x86/vp9_sad_mmx.asm
 VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_variance_impl_sse2.asm
+VP9_CX_SRCS-$(HAVE_AVX2) += encoder/x86/vp9_variance_impl_intrin_avx2.c
 VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_sad4d_sse2.asm
 VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_subpel_variance_impl_sse2.asm
 VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_temporal_filter_apply_sse2.asm
@@ -91,6 +92,7 @@ VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_error_sse2.asm
 VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_sad_sse2.asm
 VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_subtract_sse2.asm
 VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_variance_sse2.c
+VP9_CX_SRCS-$(HAVE_AVX2) += encoder/x86/vp9_variance_avx2.c
 VP9_CX_SRCS-$(HAVE_SSE2) += encoder/x86/vp9_subpel_variance.asm
 endif