src/dsp/x86/common_avx2.h

/*
 * Copyright 2020 The libgav1 Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef LIBGAV1_SRC_DSP_X86_COMMON_AVX2_H_
#define LIBGAV1_SRC_DSP_X86_COMMON_AVX2_H_

#include "src/utils/compiler_attributes.h"
#include "src/utils/cpu.h"

#if LIBGAV1_TARGETING_AVX2

#include <immintrin.h>

#include <cassert>
#include <cstddef>
#include <cstdint>

namespace libgav1 {
namespace dsp {

//------------------------------------------------------------------------------
// Load functions.

inline __m256i LoadAligned32(const void* a) {
  assert((reinterpret_cast<uintptr_t>(a) & 0x1f) == 0);
  return _mm256_load_si256(static_cast<const __m256i*>(a));
}

inline void LoadAligned64(const void* a, __m256i dst[2]) {
  assert((reinterpret_cast<uintptr_t>(a) & 0x1f) == 0);
  dst[0] = _mm256_load_si256(static_cast<const __m256i*>(a) + 0);
  dst[1] = _mm256_load_si256(static_cast<const __m256i*>(a) + 1);
}

inline __m256i LoadUnaligned32(const void* a) {
  return _mm256_loadu_si256(static_cast<const __m256i*>(a));
}

//------------------------------------------------------------------------------
// Load functions to avoid MemorySanitizer's use-of-uninitialized-value warning.

inline __m256i MaskOverreads(const __m256i source,
                             const ptrdiff_t over_read_in_bytes) {
  __m256i dst = source;
#if LIBGAV1_MSAN
  if (over_read_in_bytes >= 32) return _mm256_setzero_si256();
  if (over_read_in_bytes > 0) {
    __m128i m = _mm_set1_epi8(-1);
    for (ptrdiff_t i = 0; i < over_read_in_bytes % 16; ++i) {
      m = _mm_srli_si128(m, 1);
    }
    const __m256i mask = (over_read_in_bytes < 16)
                             ? _mm256_setr_m128i(_mm_set1_epi8(-1), m)
                             : _mm256_setr_m128i(m, _mm_setzero_si128());
    dst = _mm256_and_si256(dst, mask);
  }
#else
  static_cast<void>(over_read_in_bytes);
#endif
  return dst;
}

inline __m256i LoadAligned32Msan(const void* const source,
                                 const ptrdiff_t over_read_in_bytes) {
  return MaskOverreads(LoadAligned32(source), over_read_in_bytes);
}

inline void LoadAligned64Msan(const void* const source,
                              const ptrdiff_t over_read_in_bytes,
                              __m256i dst[2]) {
  dst[0] = MaskOverreads(LoadAligned32(source), over_read_in_bytes);
  dst[1] = MaskOverreads(LoadAligned32(static_cast<const __m256i*>(source) + 1),
                         over_read_in_bytes);
}

inline __m256i LoadUnaligned32Msan(const void* const source,
                                   const ptrdiff_t over_read_in_bytes) {
  return MaskOverreads(LoadUnaligned32(source), over_read_in_bytes);
}

//------------------------------------------------------------------------------
// Store functions.

inline void StoreAligned32(void* a, const __m256i v) {
  assert((reinterpret_cast<uintptr_t>(a) & 0x1f) == 0);
  _mm256_store_si256(static_cast<__m256i*>(a), v);
}

inline void StoreAligned64(void* a, const __m256i v[2]) {
  assert((reinterpret_cast<uintptr_t>(a) & 0x1f) == 0);
  _mm256_store_si256(static_cast<__m256i*>(a) + 0, v[0]);
  _mm256_store_si256(static_cast<__m256i*>(a) + 1, v[1]);
}

inline void StoreUnaligned32(void* a, const __m256i v) {
  _mm256_storeu_si256(static_cast<__m256i*>(a), v);
}

}  // namespace dsp
}  // namespace libgav1

#endif  // LIBGAV1_TARGETING_AVX2
#endif  // LIBGAV1_SRC_DSP_X86_COMMON_AVX2_H_