[PATCH v2 1/1] sysdeps/x86: set Prefer_No_AVX512 for Hygon model 0x7

[Jiamei Xie]

Hi，

Just a gentle ping on this patch. it has already received a Reviewed-by but has not been merged to master.
Please let me know if anything else is needed before the merge.

Thanks!
Jiamei

> -----Original Message-----
> From: H.J. Lu <hjl.tools@gmail.com>
> Sent: 2025年10月16日 7:41
> To: Jiamei Xie <xiejiamei@hygon.cn>
> Cc: libc-alpha@sourceware.org; Jing Li <lijing@hygon.cn>
> Subject: Re: [PATCH v2 1/1] sysdeps/x86: set Prefer_No_AVX512 for Hygon
> model 0x7
> 
> On Tue, Oct 14, 2025 at 5:22 PM Jiamei Xie <xiejiamei@hygon.cn> wrote:
> >
> > Benchmarks on Hygon hardware show that EVEX often outperforms AVX-512.
> > To reflect this, enable the Prefer_No_AVX512 flag for model 0x7 so
> > that the ifunc selector will favor EVEX paths over AVX-512 for that model.
> >
> > Signed-off-by: Li jing <lijing@hygon.cn>
> > Signed-off-by: Xie jiamei <xiejiamei@hygon.cn>
> > ---
> >  sysdeps/x86/cpu-features.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> > index b67ef541dd..4ec4c43718 100644
> > --- a/sysdeps/x86/cpu-features.c
> > +++ b/sysdeps/x86/cpu-features.c
> > @@ -1123,6 +1123,11 @@ disable_tsx:
> >         hardware.  */
> >        cpu_features->preferred[index_arch_Avoid_Non_Temporal_Memset]
> >             &= ~bit_arch_Avoid_Non_Temporal_Memset;
> > +
> > +      /* On Hygon model 0x7, benchmarks show EVEX often beats
> AVX-512 */
> > +      if (model == 0x7)
> > +        cpu_features->preferred[index_arch_Prefer_No_AVX512]
> > +          |= bit_arch_Prefer_No_AVX512;
> >      }
> >    else
> >      {
> > --
> > 2.17.1
> >
> >
> 
> LGTM.
> 
> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
> 
> Thanks.
> 
> --
> H.J.