Re: [PATCH] softfpu: Generalize pick_nan_muladd to opaque structures

[Alex Bennée]

Richard Henderson <richard.henderson@linaro.org> writes:

> This will allow us to share code between FloatParts and FloatParts128.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> Cc: Alex Bennee <alex.bennee@linaro.org>
>
> What do you think of this instead of inlining pick_nan_muladd
> into the two muladd implementations?

I think that can work. I was noodling about with float_addsub128 over
the weekend so I'll post what that looks like once I've tested it.

Anyway:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

>
>
> r~
>
> ---
>  fpu/softfloat.c | 40 ++++++++++++++++++++++++----------------
>  1 file changed, 24 insertions(+), 16 deletions(-)
>
> diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> index 3e625c47cd..60fdddd163 100644
> --- a/fpu/softfloat.c
> +++ b/fpu/softfloat.c
> @@ -929,16 +929,23 @@ static FloatParts pick_nan(FloatParts a, FloatParts b, 
> float_status *s)
>      return a;
>  }
>  
> -static FloatParts pick_nan_muladd(FloatParts a, FloatParts b, FloatParts c,
> -                                  bool inf_zero, float_status *s)
> +/*
> + * Given pointers to A, B, C, and the respective classes, return the
> + * pointer to the structure that is the NaN result, or NULL to signal
> + * that the result is the default NaN.
> + */
> +static inline void *
> +pick_nan_muladd(FloatClass a_cls, FloatClass b_cls, FloatClass c_cls,
> +                void *a, void *b, void *c,
> +                bool inf_zero, int abc_mask, float_status *s)
>  {
>      int which;
>  
> -    if (is_snan(a.cls) || is_snan(b.cls) || is_snan(c.cls)) {
> +    if (unlikely(abc_mask & float_cmask_snan)) {
>          s->float_exception_flags |= float_flag_invalid;
>      }
>  
> -    which = pickNaNMulAdd(a.cls, b.cls, c.cls, inf_zero, s);
> +    which = pickNaNMulAdd(a_cls, b_cls, c_cls, inf_zero, s);
>  
>      if (s->default_nan_mode) {
>          /* Note that this check is after pickNaNMulAdd so that function
> @@ -949,23 +956,16 @@ static FloatParts pick_nan_muladd(FloatParts a, 
> FloatParts b, FloatParts c,
>  
>      switch (which) {
>      case 0:
> -        break;
> +        return a;
>      case 1:
> -        a = b;
> -        break;
> +        return b;
>      case 2:
> -        a = c;
> -        break;
> +        return c;
>      case 3:
> -        return parts_default_nan(s);
> +        return NULL;
>      default:
>          g_assert_not_reached();
>      }
> -
> -    if (is_snan(a.cls)) {
> -        return parts_silence_nan(a, s);
> -    }
> -    return a;
>  }
>  
>  /*
> @@ -1366,7 +1366,15 @@ static FloatParts muladd_floats(FloatParts a, 
> FloatParts b, FloatParts c,
>       * off to the target-specific pick-a-NaN routine.
>       */
>      if (unlikely(abc_mask & float_cmask_anynan)) {
> -        return pick_nan_muladd(a, b, c, inf_zero, s);
> +        FloatParts *r = pick_nan_muladd(a.cls, b.cls, c.cls, &a, &b, &c,
> +                                        inf_zero, abc_mask, s);
> +        if (r == NULL) {
> +            return parts_default_nan(s);
> +        }
> +        if (is_snan(r->cls)) {
> +            return parts_silence_nan(*r, s);
> +        }
> +        return *r;
>      }
>  
>      if (unlikely(inf_zero)) {


-- 
Alex Bennée