[PATCH 1/N] x86_64 vectorization support: vectorized math functions addition to Glibc

[Zamyatin, Igor]

> On Wed, 12 Nov 2014, Jakub Jelinek wrote:
> 
> > Processor clause is parsed for Cilk+.  OpenMP doesn't have anything
> > like that, and I'm not sure it would be appropriate for the standard,
> > because the standard is not specific to a single CPU architecture and
> > all parties would need to agree on the names.  You actually don't care
> > about the processors anyway, but about the vector ISA.

Right, right, it's about vector ISA. Anyway some mechanism for pointing the exact ISA to be used still looks useful for different needs...
BTW processor clause were replaced by architecture clause in Cilk Plus 1.2. This clause seems to serve exactly for pointing ISA - will find out more details about it.

> 
> An alternative to having a processor clause now would be having an ABI/API
> document for OpenMP on x86_64 - agreed between implementations - that
> specifies what vector versions of a function the standard pragma means are
> available, and specifies that implementations must not generate calls to
> versions not listed unless some non-standard pragma is used to declare
> those other versions to be available (which would put off defining such a
> non-standard pragma until there is a desire to have vector versions for
> newer ISAs).

We can prepare a document that describes what compiler (gcc 4.9 and gcc5) can generate (and of course make sure that we have all those versions in glibc) for x86_64 and put it somewhere on gcc.gnu.org (e.g. Release notes?) and, say, on glibc wiki.
Will it be enough for now?

Thanks,
Igor

> 
> --
> Joseph S. Myers
> joseph@codesourcery.com