[testsuite] fix gcc.dg/torture/builtin-modf-1.c

[Jack Howarth]

Janis,
    It appears that on powerpc-apple-darwin9, we need...

-funsafe-math-optimizations -fsigned-zeros -fno-associative-math

    I am able to compile and execute the test case without errors
at -Os, -O0, -O1, -O2 and -O3 with those flags.    
                  Jack

On Wed, Dec 19, 2007 at 09:53:07AM -0800, Janis Johnson wrote:
> On Tue, 2007-12-18 at 22:00 -0500, Jack Howarth wrote:
> > Janis,
> >    On powerpc-apple-darwin9, I still get a compile failure when
> > I link with or without -funsafe-math-optimizations...
> 
> That option now changes several flags:
> 
> /* When -funsafe-math-optimizations is set the following
>    flags are set as well.  */
> void
> set_unsafe_math_optimizations_flags (int set)
> {
>   flag_trapping_math = !set;
>   flag_signed_zeros = !set;
>   flag_associative_math = set;
>   flag_reciprocal_math = set;
> }
> 
> Try setting and unsetting those individually to find out what
> might be needed for this test on Darwin.
> 
> Janis