From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22588 invoked by alias); 14 Aug 2002 16:56:02 -0000 Mailing-List: contact gcc-prs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-prs-owner@gcc.gnu.org Received: (qmail 22564 invoked by uid 71); 14 Aug 2002 16:56:01 -0000 Date: Wed, 14 Aug 2002 10:52:00 -0000 Message-ID: <20020814165601.22563.qmail@sources.redhat.com> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, From: Janis Johnson Subject: Re: middle-end/7561: Prefetch merging code in gcc-3.1/gcc/loop.c incorect Reply-To: Janis Johnson X-SW-Source: 2002-08/txt/msg00288.txt.bz2 List-Id: The following reply was made to PR middle-end/7561; it has been noted by GNATS. From: Janis Johnson To: redmond@ecf.utoronto.ca Cc: gcc-gnats@gcc.gnu.org Subject: Re: middle-end/7561: Prefetch merging code in gcc-3.1/gcc/loop.c incorect Date: Wed, 14 Aug 2002 09:46:02 -0700 On Fri, Aug 09, 2002 at 05:58:32PM -0000, redmond@ecf.utoronto.ca wrote: > > >Number: 7561 > >Category: middle-end > >Synopsis: Prefetch merging code in gcc-3.1/gcc/loop.c incorect Wow, someone is looking at the prefetch optimization code! I'm still catching up on mailing lists after a two-week vacation and didn't see your bug report until just now. In June I posted some changes to the way the prefetches are merged, and changed things in general to handle "sparse" prefetches, for which we prefetch only the cache lines containing data that will be used rather than every cache line within the section of the array being used. I had asked Jan Hubicka to take a look at it, but that was when he was in the middle of lots of other things and I never heard anything from him. If you're interested in this optimization, please take a look at http://gcc.gnu.org/ml/gcc-patches/2002-06/msg00660.html. I can update the patch to apply to the current CVS tree, which I've been meaning to do anyway; I've been distracted by other things lately. I've also got some other tweaks locally that help some of the SPEC CPU2000 floating point tests. The new code as written can't be used because it's much slower, but it's meant to demonstrate changes to how prefetches are used; once that looks OK it can be changed to do the same work more quickly. Janis Johnson IBM Linux Technology Center