From: Dave Jones <davej@suse.de>
To: Pavel Machek <pavel@suse.cz>
Cc: Ruth Ivimey-Cook <Ruth.Ivimey-Cook@ivimey.org>,
Luigi Genoni <kernel@Expansa.sns.it>,
"J.A. Magallon" <jamagallon@able.es>,
Luca Barbieri <ldb@ldb.ods.org>,
Marcelo Tosatti <marcelo@conectiva.com.br>,
Linux-Kernel ML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] [2.4] [2.5] [i386] Add support for GCC 3.1 -march=pentium{-mmx,3,4}
Date: Wed, 29 May 2002 13:42:02 +0200 [thread overview]
Message-ID: <20020529134202.F27463@suse.de> (raw)
In-Reply-To: <Pine.LNX.4.44.0205260128110.2047-100000@Expansa.sns.it> <Pine.LNX.4.44.0205260044270.10923-100000@sharra.ivimey.org> <20020526023009.G16102@suse.de> <20020527085301.A38@toy.ucw.cz>
On Mon, May 27, 2002 at 08:53:02AM +0000, Pavel Machek wrote:
> Hi!
>
> > I would be (pleasantly) surprised to see gcc turn a C memcpy into faster
> > assembly than our current implementation. And I'll bet
>
> gcc has hand-coded assembly inside itself, if gcc compiled memcpy is slower
> than hand-optimized one, you found a compiler bug.
Not at all. gcc compiled memcpy just has no knowledge of things like
non-temporal stores, and using mmx/sse to move 64 bits at a time instead
of 32 bit registers. (It's only recently it got prefetch abilities too).
--
| Dave Jones. http://www.codemonkey.org.uk
| SuSE Labs
next prev parent reply other threads:[~2002-05-29 11:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-05-25 21:01 [PATCH] [2.4] [2.5] [i386] Add support for GCC 3.1 -march=pentium{-mmx,3,4} Luca Barbieri
2002-05-25 23:37 ` J.A. Magallon
2002-05-25 22:53 ` Dave Jones
2002-05-25 23:29 ` Luigi Genoni
2002-05-25 23:49 ` Ruth Ivimey-Cook
2002-05-26 0:30 ` Dave Jones
2002-05-27 8:53 ` Pavel Machek
2002-05-29 11:42 ` Dave Jones [this message]
2002-05-29 19:57 ` Pavel Machek
2002-05-30 6:40 ` Jan Hubicka
2002-05-30 10:25 ` David Woodhouse
2002-05-30 10:45 ` Jan Hubicka
2002-05-26 1:08 ` J.A. Magallon
2002-05-26 0:21 ` Dave Jones
[not found] ` <1022380785.11859.59.camel@irongate.swansea.linux.org.uk>
2002-05-26 9:11 ` J.A. Magallon
2002-05-26 19:14 ` Alan Cox
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