cpuid.c

#include <stddef.h>
#include <stdint.h>
#include <stdio.h>

#define CPUID_EBX_AVX2    0x00000020
#define CPUID_EBX_AVX512F 0x00010000

#define XCR0_SSE       0x00000002
#define XCR0_AVX       0x00000004
#define XCR0_OPMASK    0x00000020
#define XCR0_ZMM_HI256 0x00000040
#define XCR0_HI16_ZMM  0x00000080

static void
_cpuid(unsigned int cpu_info[4U], const unsigned int cpu_info_type)
{

    __asm__ __volatile__("xchgq %%rbx, %q1; cpuid; xchgq %%rbx, %q1"
                         : "=a"(cpu_info[0]), "=&r"(cpu_info[1]),
                           "=c"(cpu_info[2]), "=d"(cpu_info[3])
                         : "0"(cpu_info_type), "2"(0U));
}

int main() {
    unsigned int cpu_info[4];
    unsigned int id;
    uint32_t     xcr0 = 0U;

    _cpuid(cpu_info, 0x0);

    __asm__ __volatile__(".byte 0x0f, 0x01, 0xd0" /* XGETBV */
		    : "=a"(xcr0)
		    : "c"((uint32_t) 0U)
		    : "%edx");

        unsigned int cpu_info7[4];

        _cpuid(cpu_info7, 0x00000007);
        printf("claims avx512f? %s \n", (cpu_info7[1] & CPUID_EBX_AVX512F) == CPUID_EBX_AVX512F  ? "yes":"no");
        printf("%x \n", ((cpu_info7[1] & CPUID_EBX_AVX512F) ) );
        printf("old code claims avx512f? %s \n", ((cpu_info7[1] & CPUID_EBX_AVX512F) != 0x0) ? "yes":"no");
        if ((cpu_info7[1] & CPUID_EBX_AVX512F) == CPUID_EBX_AVX512F &&
            (xcr0 & (XCR0_OPMASK | XCR0_ZMM_HI256 | XCR0_HI16_ZMM))
            == (XCR0_OPMASK | XCR0_ZMM_HI256 | XCR0_HI16_ZMM)) {
printf("has avx512f\n");
        }

	printf("done\n");
}