Re: [PATCH] [X86]: Fix zen6 AVX512BMM cpuid check.

On Fri, Aug 21, 2026 at 2:34 AM Dipesh Sharma <[email protected]> wrote:
>
> Hi,
>
> This patch fixes the AVX512BMM cpuid check for zen6. The AVX512BMM is
> present in the extended features instead of the standard leaf.

Where is AVX512BMM spec?  It should also be supported by
glibc.

> bootstraped and regtested on x86_64-linux-gnu. Ok for trunk ?
>
> gcc/ChangeLog:
>
>         * common/config/i386/cpuinfo.h (get_available_features): Detect AVXBMM from extended features instead of standard leaf.
> ---
>  gcc/common/config/i386/cpuinfo.h | 12 ++----------
>  1 file changed, 2 insertions(+), 10 deletions(-)
>
> diff --git a/gcc/common/config/i386/cpuinfo.h b/gcc/common/config/i386/cpuinfo.h
> index fef8f90f94c..153ab194864 100644
> --- a/gcc/common/config/i386/cpuinfo.h
> +++ b/gcc/common/config/i386/cpuinfo.h
> @@ -1110,16 +1110,6 @@ get_available_features (struct __processor_model *cpu_model,
>         }
>      }
>
> -  /* Get Advanced Features at level 0x21 (eax = 0x21).  */
> -  if (max_cpuid_level >= 0x21)
> -    {
> -      __cpuid (0x21, eax, ebx, ecx, edx);
> -      if (eax & bit_AVX512BMM)
> -       {
> -         set_feature (FEATURE_AVX512BMM);
> -       }
> -    }
> -
>    /* Get Advanced Features at level 0x24 (eax = 0x24, ecx = 0).  */
>    if (avx10_set && max_cpuid_level >= 0x24)
>      {
> @@ -1205,6 +1195,8 @@ get_available_features (struct __processor_model *cpu_model,
>         {
>           set_feature (FEATURE_PREFETCHI);
>         }
> +      if (eax & bit_AVX512BMM)
> +       set_feature (FEATURE_AVX512BMM);
>      }
>
>  #undef set_feature
> --
> 2.34.1
>


-- 
H.J.