Re: [PATCH v3 2/3] x86: Add cache information support for Zhaoxin processors

["H.J. Lu" <hjl.tools@gmail.com>]

On Thu, Apr 30, 2020 at 12:16 PM Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * Joseph Myers:
>
> > This has broken the build for 32-bit x86.
> >
> > In file included from ../sysdeps/i386/cacheinfo.c:3:
> > ../sysdeps/x86/cacheinfo.c: In function 'init_cacheinfo':
> > ../sysdeps/x86/cacheinfo.c:762:16: error: unused variable 'eax' [-Werror=unused-variable]
> >   762 |   unsigned int eax;
> >       |                ^~~
> > cc1: all warnings being treated as errors
> >
> > The variable eax in that function is only used inside #ifndef
> > DISABLE_PREFETCHW, and 32-bit defines DISABLE_PREFETCHW in
> > sysdeps/i386/cacheinfo.c.

Why didn't I see the problem with GCC 10?

> This seems to fix it.  Okay?
>
> 8<------------------------------------------------------------------8<
> Subject: i386: Remove unused variable in sysdeps/x86/cacheinfo.c
>
> Commit a98dc92dd1e278df4c501deb07985018bc2b06de ("x86: Add cache
> information support for Zhaoxin processors") introduced an unused
> variable warning in the default i686-linux-gnu build:
>
> In file included from ../sysdeps/i386/cacheinfo.c:3:
> ../sysdeps/x86/cacheinfo.c: In function 'init_cacheinfo':
> ../sysdeps/x86/cacheinfo.c:762:16: error: unused variable 'eax' [-Werror=unused-variable]
>   762 |   unsigned int eax;
>       |                ^~~
>
> -----
>  sysdeps/x86/cacheinfo.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c
> index 17d7e41aed..311502dee3 100644
> --- a/sysdeps/x86/cacheinfo.c
> +++ b/sysdeps/x86/cacheinfo.c
> @@ -759,7 +759,6 @@ __attribute__((constructor))
>  init_cacheinfo (void)
>  {
>    /* Find out what brand of processor.  */
> -  unsigned int eax;
>    unsigned int ebx;
>    unsigned int ecx;
>    unsigned int edx;
> @@ -830,6 +829,7 @@ init_cacheinfo (void)
>  #ifndef DISABLE_PREFETCHW
>        if (max_cpuid_ex >= 0x80000001)
>         {
> +         unsigned int eax;
>           __cpuid (0x80000001, eax, ebx, ecx, edx);
>           /*  PREFETCHW     || 3DNow!  */
>           if ((ecx & 0x100) || (edx & 0x80000000))

OK if it fixes the build problem.

Thanks.

-- 
H.J.