Re: [Qemu-devel] [PATCH] target-mips: silence NaNs for cvt.s.d and cvt.d.s

["Maciej W. Rozycki" <macro@linux-mips.org>]

On Sun, 6 Dec 2015, Aurelien Jarno wrote:

> cvt.s.d and cvt.d.s are FP operations and thus need to convert input
> sNaN into corresponding qNaN. Explicitely use the floatXX_maybe_silence_nan
> functions for that as the floatXX_to_floatXX functions do not do that.
> 
> Cc: Leon Alrae <leon.alrae@imgtec.com>
> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> ---
>  target-mips/op_helper.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/target-mips/op_helper.c b/target-mips/op_helper.c
> index d2c98c9..20e79be 100644
> --- a/target-mips/op_helper.c
> +++ b/target-mips/op_helper.c
> @@ -2545,6 +2545,7 @@ uint64_t helper_float_cvtd_s(CPUMIPSState *env, uint32_t fst0)
>      uint64_t fdt2;
>  
>      fdt2 = float32_to_float64(fst0, &env->active_fpu.fp_status);
> +    fdt2 = float64_maybe_silence_nan(fdt2);
>      update_fcr31(env, GETPC());
>      return fdt2;
>  }
> @@ -2634,6 +2635,7 @@ uint32_t helper_float_cvts_d(CPUMIPSState *env, uint64_t fdt0)
>      uint32_t fst2;
>  
>      fst2 = float64_to_float32(fdt0, &env->active_fpu.fp_status);
> +    fst2 = float32_maybe_silence_nan(fst2);
>      update_fcr31(env, GETPC());
>      return fst2;
>  }

 FYI, I posted a more general fix to this a while ago, however the review 
regrettably went nowhere.  See the archive of discussion starting at: 
<http://lists.nongnu.org/archive/html/qemu-devel/2014-12/msg00969.html> 
for details, including the justification and further design consideration.

  Maciej