From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9431 invoked by alias); 20 Dec 2005 07:40:52 -0000 Received: (qmail 9402 invoked by alias); 20 Dec 2005 07:40:50 -0000 Date: Tue, 20 Dec 2005 07:40:00 -0000 Message-ID: <20051220074050.9401.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug target/25500] REGREGRESSION: SSE2 vectorized code is many times slower on 4.x.x than on 3.4.4 In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "yuri at tsoft dot com" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2005-12/txt/msg02096.txt.bz2 List-Id: ------- Comment #11 from yuri at tsoft dot com 2005-12-20 07:40 ------- Subject: Re: REGREGRESSION: SSE2 vectorized code is many times slower on 4.x.x than on 3.4.4 Now this huge runtime difference disappeared but now 4.0.2-generated code is always ~> 20% slower. Many memory accesses where they are not needed at all and did not exist for 3.4.4. I tried -march=i686 and -march=k8, both are slower than 3.4.4. Do I also have to recompile gcc with some special options? Yuri pinskia at gcc dot gnu dot org wrote: >------- Comment #10 from pinskia at gcc dot gnu dot org 2005-12-20 06:55 ------- >Oh, I looked a little more and yes it depends on the arch you are building for >but only for 4.x. > >Since you are using SSE, you should add also -march=i686 or -march=k8 so that >the code is also tuned for the processor you are using. > >Anyways the problem with i386 with 4.0 is really just PR 14295. > > > > -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25500