Re: [RFC PATCH 2/8] fpu/softfloat: use the similiar logic to recognize sNaN and qNaN

[LIU Zhiwei]

On 2020/7/14 3:17, Richard Henderson wrote:

> On 7/12/20 4:45 PM, LIU Zhiwei wrote:
> > Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
> > ---
> >  fpu/softfloat-specialize.inc.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/fpu/softfloat-specialize.inc.c b/fpu/softfloat-specialize.inc.c
> > index 034d18199c..6b778a7830 100644
> > --- a/fpu/softfloat-specialize.inc.c
> > +++ b/fpu/softfloat-specialize.inc.c
> > @@ -292,7 +292,7 @@ bool float32_is_quiet_nan(float32 a_, float_status *status)
> >      if (snan_bit_is_one(status)) {
> >          return (((a >> 22) & 0x1FF) == 0x1FE) && (a & 0x003FFFFF);
> >      } else {
> > -        return ((uint32_t)(a << 1) >= 0xFF800000);
> > +        return ((a >> 22) & 0x1FF) == 0x1FF;
> >      }
> >  #endif
> >  }
> >       
> I don't see a reason for this.  The previous was a bug, but this isn't.
>     
    It's not a bug,  just a clean up.   
    
    As you can see, we have already recognized a quiet nan by 
 if (snan_bit_is_one(status)) {
         return (((a >> 22) & 0x1FF) == 0x1FE) && (a & 0x003FFFFF);
 }

    We need not to give another method to recognize it again.
    
    Zhiwei
> r~
>