David A. Greene wrote:
On Wednesday 21 January 2009 03:11, David Abrahams wrote:
on Tue Jan 20 2009, "David A. Greene" <greened-AT-obbligato.org> wrote:
When you're talking "optimal," you're setting a pretty dang high bar. I don't have to care about "optimal" if the difference between a suboptimal use of SIMD and not using it at all is an order of magnitude.
Well, the whole discussion is about "optimal." If one doesn't care about "optimal" then a compiler will do just fine all the time and there's no need for a DSEL, asm or ugly gcc intrinsics.
What if we replace optimal with optimized? Surely library code than gives a 4x speedup is desirable to have even if you can hand generate code that gives you a 5x. Getting a 4x speedup over naive simd-less in simple vector operations and still being able to concentrate on the problem at hand instead of low level optimization details sounds fantastic to me. -- Michael Marcin