[PATCH][RFH] (3/3) Vectorize some builtins on x86_64 by using libgcc-math

[Joseph S. Myers]

On Fri, 17 Nov 2006, Paolo Bonzini wrote:

> 
> > If this is a shared library, then the link command line (generated by gcc
> > when linking with -ftree-vectorize) should at least use --as-needed
> > -lgcc-math --no-as-needed (if USE_LD_AS_NEEDED) to avoid dependencies on
> > libgcc-math for programs that don't in fact need it.
> >   
> 
> This would still require libgcc-math.a to be present in order to do the
> linking, right?

Yes.  If the compiler is configured with libgcc-math then it should know 
to link against it.  If not, it should know not to try linking against it.

> OTOH, it would not need to be connected to -ftree-vectorize, but it could be
> in the default target specs for targets that have --as-needed.

Indeed, not needing -ftree-vectorize at link time would be better.  Even 
better would be the general identification of which GCC runtime libraries 
are needed listed under "User interface" at 
<http://gcc.gnu.org/projects/beginner.html> - but that's a separate 
project.

-- 
Joseph S. Myers
joseph@codesourcery.com