[PATCH v2] S390: Allow "v" constraint for long double math_opt_barrier and math_force_eval with GCC 11.

[Florian Weimer]

* Stefan Liebler via Libc-alpha:

> Starting with GCC 11, long double values can also be processed in vector
> registers if build with -march >= z14.  Then GCC defines the
> __LONG_DOUBLE_VX__ macro.
>
> FYI: GCC commit "IBM Z: Introduce __LONG_DOUBLE_VX__ macro"
> https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=f47df2af313d2ce7f9149149010a142c2237beda
> ---
>  sysdeps/s390/fpu/math-barriers.h | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/s390/fpu/math-barriers.h b/sysdeps/s390/fpu/math-barriers.h
> index 68a3e55098..13fd30017f 100644
> --- a/sysdeps/s390/fpu/math-barriers.h
> +++ b/sysdeps/s390/fpu/math-barriers.h
> @@ -21,13 +21,26 @@
>  
>  #ifdef HAVE_S390_VX_GCC_SUPPORT
>  # define ASM_CONSTRAINT_VR "v"
> +# ifdef __LONG_DOUBLE_VX__
> +/* Starting with gcc 11, long double values can also be processed in vector
> +   registers if build with -march >= z14.  Then GCC defines the
> +   __LONG_DOUBLE_VX__ macro.  */
> +#  define ASM_LONG_DOUBLE_IN_VR 1
> +# else
> +#  define ASM_LONG_DOUBLE_IN_VR 0
> +# endif
>  #else
>  # define ASM_CONSTRAINT_VR
> +# define ASM_LONG_DOUBLE_IN_VR 0
>  #endif
>  
>  #define math_opt_barrier(x)						\
>    ({ __typeof (x) __x = (x);						\
> -    if (__builtin_types_compatible_p (__typeof (x), _Float128))		\
> +    if (! ASM_LONG_DOUBLE_IN_VR						\
> +	&& (__builtin_types_compatible_p (__typeof (x), _Float128)	\
> +	    || __builtin_types_compatible_p (__typeof (x), long double)	\
> +	    )								\
> +	)								\
>        __asm__ ("# math_opt_barrier_f128 %0" : "+fm" (__x));		\
>      else								\
>        __asm__ ("# math_opt_barrier %0"					\
> @@ -35,7 +48,11 @@
>      __x; })
>  #define math_force_eval(x)						\
>    ({ __typeof (x) __x = (x);						\
> -    if (__builtin_types_compatible_p (__typeof (x), _Float128))		\
> +    if (! ASM_LONG_DOUBLE_IN_VR						\
> +	&& (__builtin_types_compatible_p (__typeof (x), _Float128)	\
> +	    || __builtin_types_compatible_p (__typeof (x), long double) \
> +	    )								\
> +	)								\
>        __asm__ __volatile__ ("# math_force_eval_f128 %0"			\
>  			    : : "fm" (__x));				\
>      else								\

This version looks good to me, thanks.