From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15490 invoked by alias); 13 Dec 2002 20:50:07 -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 15481 invoked from network); 13 Dec 2002 20:50:06 -0000 Received: from unknown (HELO book.moene.indiv.nluug.nl) (195.109.255.217) by 209.249.29.67 with SMTP; 13 Dec 2002 20:50:06 -0000 Received: from local ([127.0.0.1] helo=moene.indiv.nluug.nl) by book.moene.indiv.nluug.nl with esmtp (Exim 3.36 #1 (Debian)) id 18MwNe-00031F-00; Fri, 13 Dec 2002 21:25:54 +0100 Message-ID: <3DFA4252.3060309@moene.indiv.nluug.nl> Date: Fri, 13 Dec 2002 13:10:00 -0000 From: Toon Moene Organization: Moene Computational Physics, Maartensdijk, The Netherlands User-Agent: Mozilla/5.0 (X11; U; Linux ppc; en-US; rv:1.0.0) Gecko/20020622 Debian/1.0.0-0.woody.1 MIME-Version: 1.0 To: Richard Henderson CC: "Sanjiv Kumar Gupta, Noida" , David Edelsohn , Daniel Berlin , Dale Johannesen , gcc@gcc.gnu.org Subject: Re: possible gcse failure: not able to eliminate redundant loads References: <20021213093054.GA29293@redhat.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2002-12/txt/msg00749.txt.bz2 Richard Henderson wrote: > On Fri, Dec 13, 2002 at 11:26:34AM +0530, Sanjiv Kumar Gupta, Noida wrote: > >> b[2] = a[1]; >> for (j = 0; j < i; j++) >> { >> if (i) >> b[3] = a[1]; > Yes, this requires more knowledge than is present in loop. > > Ignoring the first statement, we cannot hoist a[1] because > it is only conditionally executed and might trap. Duh ;-) Can we disable this notion of loads-that-might-trap from a frontend ? I cannot imagine a valid Fortran program that contains an access to memory that "might trap". [ Silly things to do with your computer on a rainy Sunday afternoon: 1. Stand out in the rain. - with apologies to Monty Python ] -- Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290 Saturnushof 14, 3738 XG Maartensdijk, The Netherlands Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html Join GNU Fortran 95: http://g95.sourceforge.net/ (under construction)