Re: isnanf cleanup

[Jeff Johnston <jjohnstn at redhat dot com>]

Ken Werner wrote:
> On Friday 03 July 2009 07:19:59 pm Jeff Johnston wrote:
>   
> > Hi Craig,
> >
> > Sorry for the delay.
> >
> > Patch has a problem.  It will break spu math library.  The spu will define
> > isnan and isinf to not support float values which will override the
> > definitions in math.h.  Don't know why SPU has those macros in
> > machine/ieeefp.h but they should be rewritten to match the ones in math.h
> > or removed entirely.
> >
> > -- Jeff J.
> >     
>
> Hi,
> Why does this patch break the SPU math library?
> The reason that the isinf and isnan macros are overwritten by the 
> machine/ieeefp.h is that these are evaluated at compile time and thus faster 
> than the math.h variant which calls fpclassify. They could be rewritten to use 
> fpclassify instead of __isinfd/__isnand but we don't have an optimized 
> __fpclassifyd routine like our vectorized isnan code.
>
> -ken
>   

This breaks the SPU math library because the override macros only work 
for double arguments.
They return 0 if the value is a float.  Craig's patch has changed the 
float math routines to use isnan/isinf
instead of __isnanf/__isinff which is fine if one uses the macro in 
math.h, but in SPU's case they will never properly detect a float nan or 
float infinity.

-- Jeff J.