CpuId.h

/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
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. */

#pragma once

#include "DisableCopy.h"

namespace paddle {

// clang-format off
enum simd_t {
  SIMD_NONE   = 0,          ///< None
  SIMD_SSE    = 1 << 0,     ///< SSE
  SIMD_SSE2   = 1 << 1,     ///< SSE 2
  SIMD_SSE3   = 1 << 2,     ///< SSE 3
  SIMD_SSSE3  = 1 << 3,     ///< SSSE 3
  SIMD_SSE41  = 1 << 4,     ///< SSE 4.1
  SIMD_SSE42  = 1 << 5,     ///< SSE 4.2
  SIMD_FMA3   = 1 << 6,     ///< FMA 3
  SIMD_FMA4   = 1 << 7,     ///< FMA 4
  SIMD_AVX    = 1 << 8,     ///< AVX
  SIMD_AVX2   = 1 << 9,     ///< AVX 2
  SIMD_AVX512 = 1 << 10,    ///< AVX 512
};
// clang-format on

class SIMDFlags final {
public:
  DISABLE_COPY(SIMDFlags);

  SIMDFlags();

  static SIMDFlags const* instance();

  inline bool check(int flags) const {
    return !((simd_flags_ & flags) ^ flags);
  }

private:
  int simd_flags_ = SIMD_NONE;
};

/**
 * @brief   Check SIMD flags at runtime.
 *
 * For example.
 * @code{.cpp}
 *
 * if (HAS_SIMD(SIMD_AVX2 | SIMD_FMA4)) {
 *      avx2_fm4_stub();
 * } else if (HAS_SIMD(SIMD_AVX)) {
 *      avx_stub();
 * }
 *
 * @endcode
 */
#define HAS_SIMD(__flags) SIMDFlags::instance()->check(__flags)

/**
 * @brief   Check SIMD flags at runtime.
 *
 * 1. Check all SIMD flags at runtime:
 *
 * @code{.cpp}
 * if (HAS_AVX && HAS_AVX2) {
 *      avx2_stub();
 * }
 * @endcod
 *
 * 2. Check one SIMD flag at runtime:
 *
 * @code{.cpp}
 * if (HAS_SSE41 || HAS_SSE42) {
 *      sse4_stub();
 * }
 * @endcode
 */
// clang-format off
#define HAS_SSE     HAS_SIMD(SIMD_SSE)
#define HAS_SSE2    HAS_SIMD(SIMD_SSE2)
#define HAS_SSE3    HAS_SIMD(SIMD_SSE3)
#define HAS_SSSE3   HAS_SIMD(SIMD_SSSE3)
#define HAS_SSE41   HAS_SIMD(SIMD_SSE41)
#define HAS_SSE42   HAS_SIMD(SIMD_SSE42)
#define HAS_FMA3    HAS_SIMD(SIMD_FMA3)
#define HAS_FMA4    HAS_SIMD(SIMD_FMA4)
#define HAS_AVX     HAS_SIMD(SIMD_AVX)
#define HAS_AVX2    HAS_SIMD(SIMD_AVX2)
#define HAS_AVX512  HAS_SIMD(SIMD_AVX512)
// clang-format on

}  // namespace paddle