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Re: gcc3.1 and 3DNOW prefetch

From: Janis Johnson <janis187 at us dot ibm dot com>
To: Jan Hubicka <jh at suse dot cz>
Cc: Tom Crispin <crispin at centtech dot com>, gcc at gcc dot gnu dot org
Date: Tue, 4 Jun 2002 08:24:14 -0700
Subject: Re: gcc3.1 and 3DNOW prefetch
References: <3CFC2624.9FDF246C@centtech.com> <20020604091645.GK29372@atrey.karlin.mff.cuni.cz>

On Tue, Jun 04, 2002 at 11:16:45AM +0200, Jan Hubicka wrote:
> > 
> > I've been looking at the 3.1 source code w.r.t. to PREFETCH, and it
> > looks like only the SSE prefetch is supported, not the 3DNOW prefetch. 
> > Am I missing something?
> 
> There is 3dnow prefetch support.  SSE prefetch is used with
> priority as it is more portable and supported by all chips supporting
> 3dnow one, but when you ask for write prefetch and -march=k6/athlon you
> should get the 3dnow one.

Tom,

There are some tests that check for the appropriate use of prefetch
instructions on x86 architectures, and they can let you know which
ones to expect; in gcc/testsuite/gcc.misc-tests, see i386-prefetch.exp
and i386-pf*.

Janis

References:
- gcc3.1 and 3DNOW prefetch
  - From: Tom Crispin
- Re: gcc3.1 and 3DNOW prefetch
  - From: Jan Hubicka

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