[PATCH v3] soft-fp: Add the lack of implementation for 128 bit self-contained.

[Zong Li]

Richard Henderson <rth@twiddle.net> 於 2018年7月27日 週五 上午12:59寫道：
>
> On 07/26/2018 06:16 AM, Zong Li wrote:
> > +#define _FP_FRAC_CLZ_8(R, X)                    \
> > +  do                                            \
> > +    {                                           \
> > +      if (X##_f[7])                             \
> > +        __FP_CLZ ((R), X##_f[7]);               \
> > +      else if (X##_f[6])                        \
> > +        {                                       \
> > +          __FP_CLZ ((R), X##_f[6]);             \
> > +          (R) += _FP_W_TYPE_SIZE;               \
> > +        }                                       \
> > +      else if (X##_f[5])                        \
> ...
>
> Perhaps better as
>
> #define _FP_FRAC_CLZ_8(R, X)                   \
>   do                                           \
>     {                                          \
>       int fs8_i;                               \
>       for (fs8_i = 7; fs8_i > 0; fs8_i--)      \
>         if (X##_f[fs8_i])                      \
>           break;                               \
>       __FP_CLZ ((R), X##_f[fs8_i]);            \
>       (R) += _FP_W_TYPE_SIZE * (7 - fs8_i);    \
>     }                                          \
>   while (0)
>
>
Yes, I use for loop at one time before I summit this patch version.
But I have a little bit
worry about the performance in this macro, because it will get more branch and
instructions by looping opposite to ADD and SUB macro change to use loop.