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 {

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
};

class SIMDFlags final {
public:
    DISABLE_COPY(SIMDFlags);
    SIMDFlags();

    static SIMDFlags const* instance();
    bool check(int flags) const;

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: HAS_SSE && HAS_SSE2 && HAS_SSE3 
 * 2. Check one SIMD flags at runtime: HAS_SSE || HAS_SSE2 || HAS_SSE3 
 */
#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)

}   // namespace paddle