RFC: Patch to allow use of DECL_NAME in libmvec calls instead of DECL_ASSEMBER_NAME

Jakub Jelinek jakub@redhat.com
Wed Mar 13 13:27:00 GMT 2019


On Wed, Mar 13, 2019 at 02:07:29PM +0100, Jakub Jelinek wrote:
> On Wed, Mar 13, 2019 at 01:00:58PM +0000, Joseph Myers wrote:
> > > Yeah, an alias doesn't really cost much, and has the advantage that if in
> > > the vector version you need at some point to differentiate between the
> > > finite only vs. full implementations, you can just by tweaking libmvec
> > > implementation, the callers will have proper calls depending on if they were
> > > compiled with -Ofast or -O3 etc.
> > 
> > Experience is showing that some or all of the finite-only versions in 
> > glibc were mistaken premature optimization - that proper optimized 
> > implementations do not gain anything from adding a finite-only 
> > restriction.  There is no good basis to suppose that if additional 
> > variants of the vector functions were useful in future, finite-only would 
> > be the right conditional (or that the right set of variants would be the 
> > same as the right set of variants for scalar functions).
> 
> If the finite only doesn't buy anything, then another option is to drop the
> math-finite.h stuff or portions thereof.
> But adding a new GCC extension that other compilers will need to implement
> too, instead of just adding a couple of aliases seems to be overkill to me.

Not to mention that fixing it on the glibc side will make it work also with
GCC 8, GCC 7 and GCC 6.

	Jakub



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