From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9734 invoked by alias); 16 Dec 2002 21:03:44 -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 9727 invoked from network); 16 Dec 2002 21:03:43 -0000 Received: from unknown (HELO book.moene.indiv.nluug.nl) (195.109.255.217) by sources.redhat.com with SMTP; 16 Dec 2002 21:03:43 -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 18O2PC-0003zA-00; Mon, 16 Dec 2002 22:04:02 +0100 Message-ID: <3DFE3FC1.9020802@moene.indiv.nluug.nl> Date: Mon, 16 Dec 2002 13:13:00 -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: gcc@gcc.gnu.org Subject: Re: possible gcse failure: not able to eliminate redundant loads References: <20021213093054.GA29293@redhat.com> <3DFA4252.3060309@moene.indiv.nluug.nl> <20021216180441.C3953@redhat.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2002-12/txt/msg00927.txt.bz2 Richard Henderson wrote: > On Fri, Dec 13, 2002 at 09:25:54PM +0100, Toon Moene wrote: >>I cannot imagine a valid Fortran program that contains an access to >>memory that "might trap". > Yeah, I guess there's really no concept of a null pointer is there... Well, certainly not in the language that g77 compiles (a superset of Fortran 77), because there is no concept of "pointer" in that language. However, Fortran 90/95 *do* have pointers, but also there it's not legally possible to "dereference" (to use the C-term) pointers that point to storage that has not been "defined" (given a value) - to say nothing of to point to something that isn't there (i.e., a pointer that hasn't been initialised to point to an existing object). BTW, I wasn't aware it's legal to dereference NULL C pointers. -- 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)