From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22506 invoked by alias); 19 Jan 2004 12:36:56 -0000 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 Received: (qmail 22499 invoked from network); 19 Jan 2004 12:36:55 -0000 Received: from unknown (HELO colossus.systems.pipex.net) (62.241.160.73) by sources.redhat.com with SMTP; 19 Jan 2004 12:36:55 -0000 Received: from nowt.org (81-178-208-226.dsl.pipex.com [81.178.208.226]) by colossus.systems.pipex.net (Postfix) with ESMTP id 1AF321C000B3; Mon, 19 Jan 2004 12:36:53 +0000 (GMT) Received: from finch.home (finch.home [192.168.1.6]) by nowt.org (Postfix) with ESMTP id 1AAC7AC96; Mon, 19 Jan 2004 12:36:53 +0000 (GMT) From: Paul Brook Organization: CodeSourcery To: kenner@vlsi1.ultra.nyu.edu (Richard Kenner), hubicka@ucw.cz Subject: Re: [RFC] Contributing tree-ssa to mainline Date: Mon, 19 Jan 2004 12:36:00 -0000 User-Agent: KMail/1.5.4 Cc: gcc@gcc.gnu.org References: <10401191226.AA27734@vlsi1.ultra.nyu.edu> In-Reply-To: <10401191226.AA27734@vlsi1.ultra.nyu.edu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200401191236.52724.paul@codesourcery.com> X-SW-Source: 2004-01/txt/msg01268.txt.bz2 On Monday 19 January 2004 12:26 pm, Richard Kenner wrote: > A case I know about in Ada is check elimination. Because the default for > Ada is enabling checking, it's quite important to eliminate checks that can > be proven not to fail. Theoretically, a lot this could be > language-independent optimizers by value range propagation and related > optimizations. But the front-end can do a much better job because it has > information only it knows. Moreover, by suppressing the check before > generating any code for it, compilation time is reduced. I think this is > clearly the proper place for that optimization. I don't know what form of checking is performed in Ada, but optimizations to remove array bound checks would also be useful for fortran. Particularly Fortran90 where it is much more common to know the shape of an array. Admittedly -fbounds-check is turned on by default in fortran, but neither is -O2. Paul