如何检查CPU是否支持SSE3指令集？

Question

对于检查CPU是否支持SSE3指令集，以下代码是否有效？

在Windows XP上使用IsProcessorFeaturePresent()函数显然不起作用(参见http://msdn.microsoft.com/en-us/library/ms724482(v=vs.85).aspx。

bool CheckSSE3()
{
    int CPUInfo[4] = {-1};

    //-- Get number of valid info ids
    __cpuid(CPUInfo, 0);
    int nIds = CPUInfo[0];

    //-- Get info for id "1"
    if (nIds >= 1)
    {
        __cpuid(CPUInfo, 1);
        bool bSSE3NewInstructions = (CPUInfo[2] & 0x1) || false;
        return bSSE3NewInstructions;     
    }

    return false;      
}

Answer 1

我已经创建了一个GitHub repro，它将检测对所有主要的x86 ISA扩展的CPU和OS支持：https://github.com/Mysticial/FeatureDetector

下面是一个简短的版本：

首先，您需要访问CPUID指令：

#ifdef _WIN32

//  Windows
#define cpuid(info, x)    __cpuidex(info, x, 0)

#else

//  GCC Intrinsics
#include <cpuid.h>
void cpuid(int info[4], int InfoType){
    __cpuid_count(InfoType, 0, info[0], info[1], info[2], info[3]);
}

#endif

然后，您可以运行以下代码：

//  Misc.
bool HW_MMX;
bool HW_x64;
bool HW_ABM;      // Advanced Bit Manipulation
bool HW_RDRAND;
bool HW_BMI1;
bool HW_BMI2;
bool HW_ADX;
bool HW_PREFETCHWT1;

//  SIMD: 128-bit
bool HW_SSE;
bool HW_SSE2;
bool HW_SSE3;
bool HW_SSSE3;
bool HW_SSE41;
bool HW_SSE42;
bool HW_SSE4a;
bool HW_AES;
bool HW_SHA;

//  SIMD: 256-bit
bool HW_AVX;
bool HW_XOP;
bool HW_FMA3;
bool HW_FMA4;
bool HW_AVX2;

//  SIMD: 512-bit
bool HW_AVX512F;    //  AVX512 Foundation
bool HW_AVX512CD;   //  AVX512 Conflict Detection
bool HW_AVX512PF;   //  AVX512 Prefetch
bool HW_AVX512ER;   //  AVX512 Exponential + Reciprocal
bool HW_AVX512VL;   //  AVX512 Vector Length Extensions
bool HW_AVX512BW;   //  AVX512 Byte + Word
bool HW_AVX512DQ;   //  AVX512 Doubleword + Quadword
bool HW_AVX512IFMA; //  AVX512 Integer 52-bit Fused Multiply-Add
bool HW_AVX512VBMI; //  AVX512 Vector Byte Manipulation Instructions

int info[4];
cpuid(info, 0);
int nIds = info[0];

cpuid(info, 0x80000000);
unsigned nExIds = info[0];

//  Detect Features
if (nIds >= 0x00000001){
    cpuid(info,0x00000001);
    HW_MMX    = (info[3] & ((int)1 << 23)) != 0;
    HW_SSE    = (info[3] & ((int)1 << 25)) != 0;
    HW_SSE2   = (info[3] & ((int)1 << 26)) != 0;
    HW_SSE3   = (info[2] & ((int)1 <<  0)) != 0;

    HW_SSSE3  = (info[2] & ((int)1 <<  9)) != 0;
    HW_SSE41  = (info[2] & ((int)1 << 19)) != 0;
    HW_SSE42  = (info[2] & ((int)1 << 20)) != 0;
    HW_AES    = (info[2] & ((int)1 << 25)) != 0;

    HW_AVX    = (info[2] & ((int)1 << 28)) != 0;
    HW_FMA3   = (info[2] & ((int)1 << 12)) != 0;

    HW_RDRAND = (info[2] & ((int)1 << 30)) != 0;
}
if (nIds >= 0x00000007){
    cpuid(info,0x00000007);
    HW_AVX2   = (info[1] & ((int)1 <<  5)) != 0;

    HW_BMI1        = (info[1] & ((int)1 <<  3)) != 0;
    HW_BMI2        = (info[1] & ((int)1 <<  8)) != 0;
    HW_ADX         = (info[1] & ((int)1 << 19)) != 0;
    HW_SHA         = (info[1] & ((int)1 << 29)) != 0;
    HW_PREFETCHWT1 = (info[2] & ((int)1 <<  0)) != 0;

    HW_AVX512F     = (info[1] & ((int)1 << 16)) != 0;
    HW_AVX512CD    = (info[1] & ((int)1 << 28)) != 0;
    HW_AVX512PF    = (info[1] & ((int)1 << 26)) != 0;
    HW_AVX512ER    = (info[1] & ((int)1 << 27)) != 0;
    HW_AVX512VL    = (info[1] & ((int)1 << 31)) != 0;
    HW_AVX512BW    = (info[1] & ((int)1 << 30)) != 0;
    HW_AVX512DQ    = (info[1] & ((int)1 << 17)) != 0;
    HW_AVX512IFMA  = (info[1] & ((int)1 << 21)) != 0;
    HW_AVX512VBMI  = (info[2] & ((int)1 <<  1)) != 0;
}
if (nExIds >= 0x80000001){
    cpuid(info,0x80000001);
    HW_x64   = (info[3] & ((int)1 << 29)) != 0;
    HW_ABM   = (info[2] & ((int)1 <<  5)) != 0;
    HW_SSE4a = (info[2] & ((int)1 <<  6)) != 0;
    HW_FMA4  = (info[2] & ((int)1 << 16)) != 0;
    HW_XOP   = (info[2] & ((int)1 << 11)) != 0;
}

请注意，这仅检测CPU是否支持指令。要实际运行它们，您还需要有操作系统支持。

具体而言，以下操作需要操作系统支持：

• x64说明。(您需要使用(AVX) 256位ymm寄存器的64位OS.)
• Instructions。有关如何检测使用(AVX512) 512位zmm和掩码寄存器的this.
• Instructions，请参阅Andy Lutomirski's answer。检测操作系统对AVX512的支持与检测AVX相同，但使用标志0xe6而不是0x6.

Answer 2

Mysticial的答案有点危险--它解释了如何检测CPU支持，而不是操作系统支持。您需要使用_xgetbv检查操作系统是否启用了所需的CPU扩展状态。有关其他来源的信息，请参阅here。Even gcc has made the same mistake.代码的要点是：

bool avxSupported = false;

int cpuInfo[4];
__cpuid(cpuInfo, 1);

bool osUsesXSAVE_XRSTORE = cpuInfo[2] & (1 << 27) || false;
bool cpuAVXSuport = cpuInfo[2] & (1 << 28) || false;

if (osUsesXSAVE_XRSTORE && cpuAVXSuport)
{
    unsigned long long xcrFeatureMask = _xgetbv(_XCR_XFEATURE_ENABLED_MASK);
    avxSupported = (xcrFeatureMask & 0x6) == 0x6;
}

Answer 3

经过相当多的谷歌搜索，我也找到了来自英特尔的解决方案：

链接：https://software.intel.com/en-us/articles/how-to-detect-new-instruction-support-in-the-4th-generation-intel-core-processor-family

    void cpuid(uint32_t eax, uint32_t ecx, uint32_t* abcd) {
#if defined(_MSC_VER)
            __cpuidex((int*)abcd, eax, ecx);
#else
            uint32_t ebx, edx;
# if defined( __i386__ ) && defined ( __PIC__ )
            /* in case of PIC under 32-bit EBX cannot be clobbered */
            __asm__("movl %%ebx, %%edi \n\t cpuid \n\t xchgl %%ebx, %%edi" : "=D" (ebx),
# else
            __asm__("cpuid" : "+b" (ebx),
# endif
            "+a" (eax), "+c" (ecx), "=d" (edx));
            abcd[0] = eax; abcd[1] = ebx; abcd[2] = ecx; abcd[3] = edx;
#endif
    }

    int check_xcr0_ymm()
    {
        uint32_t xcr0;
#if defined(_MSC_VER)
        xcr0 = (uint32_t)_xgetbv(0);  /* min VS2010 SP1 compiler is required */
#else
        __asm__("xgetbv" : "=a" (xcr0) : "c" (0) : "%edx");
#endif
        return ((xcr0 & 6) == 6); /* checking if xmm and ymm state are enabled in XCR0 */
    }

还要注意，GCC有一些可以使用的特殊内部函数(请参阅：https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/X86-Built-in-Functions.html )：

    if (__builtin_cpu_supports("avx2"))
    // ...

如果你把这些和上面的信息放在一起，一切都会好起来的。