[PATCH] x86: Handle unknown family CPUs with default tuning

[H.J. Lu]

On Thu, Apr 10, 2025 at 6:48 PM Sunil K Pandey <sunil.k.pandey@intel.com> wrote:
>
> If AVX is available, enable default tuning
> - Rep string instruction
> - Unaligned load
> - Unaligned copy
> - Pminub for stringop
>
> Tested on x86, no regression.
> ---
>  sysdeps/x86/cpu-features.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> index f1d2a179e4..d338e88397 100644
> --- a/sysdeps/x86/cpu-features.c
> +++ b/sysdeps/x86/cpu-features.c
> @@ -932,6 +932,18 @@ https://www.intel.com/content/www/us/en/support/articles/000059422/processors.ht
>                 break;
>             }
>         }
> +      else
> +       {
> +         /* Unknown family processor.  Enable default tuning.  */
> +         if (CPU_FEATURES_CPU_P (cpu_features, AVX))
> +           /* Rep string instructions, unaligned load, unaligned copy,
> +              and pminub are fast on Intel Core i3, i5 and i7.  */
> +           cpu_features->preferred[index_arch_Fast_Rep_String]
> +             |= (bit_arch_Fast_Rep_String
> +                 | bit_arch_Fast_Unaligned_Load
> +                 | bit_arch_Fast_Unaligned_Copy
> +                 | bit_arch_Prefer_PMINUB_for_stringop);
> +       }

Please do

  unsigned int microarch = INTEL_UNKNOWN;
   if (family == 0x06)
    {
        model += extended_model;
        microarch = intel_get_fam6_microarch (model, stepping);
    }

    switch (microarch)
       {
       }

>
>        /* Since AVX512ER is unique to Xeon Phi, set Prefer_No_VZEROUPPER
> --
> 2.49.0
>


-- 
H.J.