From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27717 invoked by alias); 18 Nov 2005 02:13:35 -0000 Received: (qmail 27705 invoked by uid 22791); 18 Nov 2005 02:13:35 -0000 X-Spam-Check-By: sourceware.org Received: from nevyn.them.org (HELO nevyn.them.org) (66.93.172.17) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 18 Nov 2005 02:13:34 +0000 Received: from drow by nevyn.them.org with local (Exim 4.54) id 1Ecvkn-00087J-Ka; Thu, 17 Nov 2005 21:13:29 -0500 Date: Fri, 18 Nov 2005 02:13:00 -0000 From: Daniel Jacobowitz To: Ian Lance Taylor Cc: Robert Dewar , Richard Earnshaw , gcc mailing list Subject: Re: Link-time optimzation Message-ID: <20051118021329.GA31135@nevyn.them.org> Mail-Followup-To: Ian Lance Taylor , Robert Dewar , Richard Earnshaw , gcc mailing list References: <437BB214.1070306@codesourcery.com> <20051117011900.GA17847@redhat.com> <437BDC9E.3080608@codesourcery.com> <1132227692.24110.40.camel@pc960.cambridge.arm.com> <437D0DC7.7040509@adacore.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.8i Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2005-11/txt/msg00817.txt.bz2 On Thu, Nov 17, 2005 at 03:42:29PM -0800, Ian Lance Taylor wrote: > I just tried a simple unoptimized compile. -ftime-report said that > final took 5% of the time (obviously final does more than formatting), > and the assembler took 4% of the total user time, and system time took > 16% of wall clock time. Cutting those numbers in half makes 1% seem > not implausible to me, maybe even low. > > I'm considering an unoptimized compile because that is where the > assembler makes the most difference--the compiler is faster and the > assembler output probably tends to be longer, and also an unoptimized > compile is when people care most about speed. For an optimizing > compile, the assembler is obviously going to be less of a factor. Also, please keep in mind that generating and then assembling debug info takes a huge amount of I/O relative to code size. I'd expect much more than 1% saving the write-out and write-in on -g. -- Daniel Jacobowitz CodeSourcery, LLC