PATCH: Check GLIBC_IFUNC to enable/disable ifunc features

[Siddhesh Poyarekar]

On Thu, Jun 30, 2016 at 05:01:28AM -0700, H.J. Lu wrote:
> My scheme is
> 
> do
> {
>   if (*env == GLIBC_IFUNC=.*)
>    {
>       process
>       break
>    }
>   env++
> }
> 
> We only need to check GLIBC_IFUNC only if it hasn't been found.  With
> GLIBC_IFUNC_X86_XXX, we have to do
> 
> do
>   {
>      if (*env == GLIBC_IFUNC_X86_*)
>        process
>      env++
>   }
> 
> We need to check GLIBC_IFUNC_X86 in each iteration.

OK, then how about GLIBC_IFUNC_X86=avx,sse2,sse3..., i.e. a
comma-separated value for the GLIBC_IFUNC_<ARCH> environment variable.

Siddhesh