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Re: preliminary patch: prefetch support for i386
- From: Jan Hubicka <jh at suse dot cz>
- To: Richard Henderson <rth at redhat dot com>, Janis Johnson <janis187 at us dot ibm dot com>, gcc-patches at gcc dot gnu dot org
- Date: Fri, 30 Nov 2001 21:21:24 +0100
- Subject: Re: preliminary patch: prefetch support for i386
- References: <20011129130113.A4811@us.ibm.com> <20011129133840.F31482@redhat.com>
> On Thu, Nov 29, 2001 at 01:01:13PM -0800, Janis Johnson wrote:
> > If a specified architecture (via -march) supports data prefetch
> > instructions then an additional option for extensions shouldn't
> > be necessary ...
>
> Yes, but that's where things get confusing, with P1, P1+MMX,
> P2, P2+MMX, P3, P4, K6, K6+3dNow, Athlon, Athlon+SSE...
> So at present we just have -mmmx/-msse/-msse2/-m3dnow to
> enable the various extensions.
>
> Suggestions for how to do it better?
Thinks get trickier, as athlon has better 3dnow than k6 did, P4 has better SSE
than P3 did and so on. I guess the better (not ideal) way is to add cpu table
entries for each such variant - they are not too numberous.
There is really P2 with and without MMX?
Honza
>
>
> r~