From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9358 invoked by alias); 27 Aug 2010 15:09:57 -0000 Received: (qmail 9348 invoked by uid 22791); 27 Aug 2010 15:09:56 -0000 X-SWARE-Spam-Status: No, hits=-1.8 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,TW_FC X-Spam-Check-By: sourceware.org Received: from mail-gx0-f175.google.com (HELO mail-gx0-f175.google.com) (209.85.161.175) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 27 Aug 2010 15:09:48 +0000 Received: by gxk2 with SMTP id 2so1371421gxk.20 for ; Fri, 27 Aug 2010 08:09:46 -0700 (PDT) MIME-Version: 1.0 Received: by 10.151.62.9 with SMTP id p9mr1983517ybk.122.1282921786181; Fri, 27 Aug 2010 08:09:46 -0700 (PDT) Received: by 10.231.13.77 with HTTP; Fri, 27 Aug 2010 08:09:45 -0700 (PDT) In-Reply-To: <1282921326.2931.17.camel@MILLC-COREY> References: <1282916665.2100.39.camel@MILLC-COREY> <20100827135005.GO16898@codesourcery.com> <1282921326.2931.17.camel@MILLC-COREY> Date: Fri, 27 Aug 2010 15:40:00 -0000 Message-ID: Subject: Re: Better performance on older version of GCC From: Richard Guenther To: Corey Kasten Cc: Nathan Froyd , gcc@gcc.gnu.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2010-08/txt/msg00403.txt.bz2 On Fri, Aug 27, 2010 at 5:02 PM, Corey Kasten wrote: > On Fri, 2010-08-27 at 06:50 -0700, Nathan Froyd wrote: >> On Fri, Aug 27, 2010 at 09:44:25AM -0400, Corey Kasten wrote: >> > I find that the executable compiled on system A runs faster (on both >> > systems) than the executable compiled on system B (on both system), by= a >> > factor about approximately 4 times. I have attempted to play with the >> > GCC optimizer flags and have not been able to get System B (with the >> > later GCC version) to compile code with any better performance. Could >> > someone please help figure this out? >> >> It's almost impossible to tell what's going on without an actual >> testcase. =A0You might not be able to provide the actual code, but you >> could try distilling it down to something you could release. >> >> -Nathan > > Thanks for the reply Nathan. > > I have attached an archive with the test case code. The code is built by > build.sh and outputs the number of microseconds to complete the > processing. > > Compiling with GCC version "4.1.2 20070925 (Red Hat 4.1.2-33)" produces > code that runs in about 66% of the time than does GCC version "4.3.0 > 20080428 (Red Hat 4.3.0-8)" -fcx-limited-range or -fcx-fortran-rules. 4.3 now is more conforming than = 4.1. Richard. > Thanks > > Corey >