Remove runtime CPU detection for SSE optimized media/ methods.

media/base/simd/vector_math_sse.cc

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "media/base/vector_math_testing.h"
-
-#include <algorithm>
-
-#include <xmmintrin.h>  // NOLINT
-
-namespace media {
-namespace vector_math {
-
-void FMUL_SSE(const float src[], float scale, int len, float dest[]) {
-  const int rem = len % 4;
-  const int last_index = len - rem;
-  __m128 m_scale = _mm_set_ps1(scale);
-  for (int i = 0; i < last_index; i += 4)
-    _mm_store_ps(dest + i, _mm_mul_ps(_mm_load_ps(src + i), m_scale));
-
-  // Handle any remaining values that wouldn't fit in an SSE pass.
-  for (int i = last_index; i < len; ++i)
-    dest[i] = src[i] * scale;
-}
-
-void FMAC_SSE(const float src[], float scale, int len, float dest[]) {
-  const int rem = len % 4;
-  const int last_index = len - rem;
-  __m128 m_scale = _mm_set_ps1(scale);
-  for (int i = 0; i < last_index; i += 4) {
-    _mm_store_ps(dest + i, _mm_add_ps(_mm_load_ps(dest + i),
-                 _mm_mul_ps(_mm_load_ps(src + i), m_scale)));
-  }
-
-  // Handle any remaining values that wouldn't fit in an SSE pass.
-  for (int i = last_index; i < len; ++i)
-    dest[i] += src[i] * scale;
-}
-
-// Convenience macro to extract float 0 through 3 from the vector |a|.  This is
-// needed because compilers other than clang don't support access via
-// operator[]().
-#define EXTRACT_FLOAT(a, i) \
-    (i == 0 ? \
-         _mm_cvtss_f32(a) : \
-         _mm_cvtss_f32(_mm_shuffle_ps(a, a, i)))
-
-std::pair<float, float> EWMAAndMaxPower_SSE(
-    float initial_value, const float src[], int len, float smoothing_factor) {
-  // When the recurrence is unrolled, we see that we can split it into 4
-  // separate lanes of evaluation:
-  //
-  // y[n] = a(S[n]^2) + (1-a)(y[n-1])
-  //      = a(S[n]^2) + (1-a)^1(aS[n-1]^2) + (1-a)^2(aS[n-2]^2) + ...
-  //      = z[n] + (1-a)^1(z[n-1]) + (1-a)^2(z[n-2]) + (1-a)^3(z[n-3])
-  //
-  // where z[n] = a(S[n]^2) + (1-a)^4(z[n-4]) + (1-a)^8(z[n-8]) + ...
-  //
-  // Thus, the strategy here is to compute z[n], z[n-1], z[n-2], and z[n-3] in
-  // each of the 4 lanes, and then combine them to give y[n].
-
-  const int rem = len % 4;
-  const int last_index = len - rem;
-
-  const __m128 smoothing_factor_x4 = _mm_set_ps1(smoothing_factor);
-  const float weight_prev = 1.0f - smoothing_factor;
-  const __m128 weight_prev_x4 = _mm_set_ps1(weight_prev);
-  const __m128 weight_prev_squared_x4 =
-      _mm_mul_ps(weight_prev_x4, weight_prev_x4);
-  const __m128 weight_prev_4th_x4 =
-      _mm_mul_ps(weight_prev_squared_x4, weight_prev_squared_x4);
-
-  // Compute z[n], z[n-1], z[n-2], and z[n-3] in parallel in lanes 3, 2, 1 and
-  // 0, respectively.
-  __m128 max_x4 = _mm_setzero_ps();
-  __m128 ewma_x4 = _mm_setr_ps(0.0f, 0.0f, 0.0f, initial_value);
-  int i;
-  for (i = 0; i < last_index; i += 4) {
-    ewma_x4 = _mm_mul_ps(ewma_x4, weight_prev_4th_x4);
-    const __m128 sample_x4 = _mm_load_ps(src + i);
-    const __m128 sample_squared_x4 = _mm_mul_ps(sample_x4, sample_x4);
-    max_x4 = _mm_max_ps(max_x4, sample_squared_x4);
-    // Note: The compiler optimizes this to a single multiply-and-accumulate
-    // instruction:
-    ewma_x4 = _mm_add_ps(ewma_x4,
-                         _mm_mul_ps(sample_squared_x4, smoothing_factor_x4));
-  }
-
-  // y[n] = z[n] + (1-a)^1(z[n-1]) + (1-a)^2(z[n-2]) + (1-a)^3(z[n-3])
-  float ewma = EXTRACT_FLOAT(ewma_x4, 3);
-  ewma_x4 = _mm_mul_ps(ewma_x4, weight_prev_x4);
-  ewma += EXTRACT_FLOAT(ewma_x4, 2);
-  ewma_x4 = _mm_mul_ps(ewma_x4, weight_prev_x4);
-  ewma += EXTRACT_FLOAT(ewma_x4, 1);
-  ewma_x4 = _mm_mul_ss(ewma_x4, weight_prev_x4);
-  ewma += EXTRACT_FLOAT(ewma_x4, 0);
-
-  // Fold the maximums together to get the overall maximum.
-  max_x4 = _mm_max_ps(max_x4,
-                      _mm_shuffle_ps(max_x4, max_x4, _MM_SHUFFLE(3, 3, 1, 1)));
-  max_x4 = _mm_max_ss(max_x4, _mm_shuffle_ps(max_x4, max_x4, 2));
-
-  std::pair<float, float> result(ewma, EXTRACT_FLOAT(max_x4, 0));
-
-  // Handle remaining values at the end of |src|.
-  for (; i < len; ++i) {
-    result.first *= weight_prev;
-    const float sample = src[i];
-    const float sample_squared = sample * sample;
-    result.first += sample_squared * smoothing_factor;
-    result.second = std::max(result.second, sample_squared);
-  }
-
-  return result;
-}
-
-}  // namespace vector_math
-}  // namespace media