Re: weird optimization in sin+cos, x86 backend

[Andrew Haley <aph at redhat dot com>]

On 02/16/2012 02:42 PM, Vincent Lefevre wrote:
> On 2012-02-15 15:18:45 +0000, Andrew Haley wrote:
> > >  On 02/15/2012 09:30 AM, Vincent Lefevre wrote:
> > > > >  >>  But to be absolutely clear, glibc's libm doesn't have a problem
> > > > > > >>  meeting C99, AFAIK.
> > > >  >  That's not quite correct. It is completely broken in directed
> > > >  >  rounding modes (up to crashes).
> > >
> > >  Eh?  C99 doesn't require directed rounding modes.  I'll grant you,
> > >  if they are provided they shouldn't crash.  :-)
> C99 doesn't require directed rounding modes, but as long as they
> are claimed to be supported by<fenv.h>, they should work:

Ah, I see.  So, we could bring gcc+glibc into compliance by not
defining the rounding mode macros.

Andrew.