numpy/distutils/checks/cpu_popcnt.c

#if defined(DETECT_FEATURES) && defined(__INTEL_COMPILER)
    /*
     * Unlike GCC and CLANG, Intel Compiler exposes all supported intrinsics,
     * whether or not the build options for those features are specified.
     * Therefore, we must test #definitions of CPU features when option native/host
     * is enabled via `--cpu-baseline` or through env vr `CFLAGS` otherwise
     * the test will be broken and leads to enable all possible features.
     */
    #if !defined(__SSE4_2__) && !defined(__POPCNT__)
        #error "HOST/ARCH doesn't support POPCNT"
    #endif
#endif

#ifdef _MSC_VER
    #include <nmmintrin.h>
#else
    #include <popcntintrin.h>
#endif

int main(int argc, char **argv)
{
    // To make sure popcnt instructions are generated
    // and been tested against the assembler
    unsigned long long a = *((unsigned long long*)argv[argc-1]);
    unsigned int b = *((unsigned int*)argv[argc-2]);

#if defined(_M_X64) || defined(__x86_64__)
    a = _mm_popcnt_u64(a);
#endif
    b = _mm_popcnt_u32(b);
    return (int)a + b;
}