Re: [Qemu-devel] [PATCH v2 3/4] softfloat: Specialize udiv_qrnnd for s390x

[David Hildenbrand <david@redhat.com>]

On 03/10/2018 20:07, Richard Henderson wrote:
> The ISA has a 128/64-bit division instruction.
> 
> Cc: qemu-s390x@nongnu.org
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: David Hildenbrand <david@redhat.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  include/fpu/softfloat-macros.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/fpu/softfloat-macros.h b/include/fpu/softfloat-macros.h
> index 6d58615709..e702607b43 100644
> --- a/include/fpu/softfloat-macros.h
> +++ b/include/fpu/softfloat-macros.h
> @@ -626,6 +626,12 @@ static inline uint64_t udiv_qrnnd(uint64_t *r, uint64_t n1,
>      uint64_t q;
>      asm("divq %4" : "=a"(q), "=d"(*r) : "0"(n0), "1"(n1), "rm"(d));
>      return q;
> +#elif defined(__s390x__)
> +    /* Need to use a TImode type to get an even register pair for DLGR.  */
> +    unsigned __int128 n = (unsigned __int128)n1 << 64 | n0;
> +    asm("dlgr %0, %1" : "+r"(n) : "r"(d));
> +    *r = n >> 64;
> +    return n;
>  #else
>      uint64_t d0, d1, q0, q1, r1, r0, m;
>  
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 

Thanks,

David / dhildenb