Subject: Re: [boost] [OT?] SIMD and Auto-Vectorization (was Re: How to structurate libraries ?)
From: Michael Marcin (mike.marcin_at_[hidden])
Date: 2009-01-21 21:07:58
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
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