From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23852 invoked by alias); 4 Nov 2002 17:06:10 -0000 Mailing-List: contact gcc-prs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-prs-owner@gcc.gnu.org Received: (qmail 23813 invoked by uid 71); 4 Nov 2002 17:06:10 -0000 Date: Mon, 04 Nov 2002 09:06:00 -0000 Message-ID: <20021104170610.23804.qmail@sources.redhat.com> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, From: "Joseph S. Myers" Subject: Re: c/8395: gcc 2.95.4 and 3.2 generate wrong code for double on intel Reply-To: "Joseph S. Myers" X-SW-Source: 2002-11/txt/msg00168.txt.bz2 List-Id: The following reply was made to PR c/8395; it has been noted by GNATS. From: "Joseph S. Myers" To: Marco Bernardo Cc: Bruce Allen , Bruce Allen , , , Subject: Re: c/8395: gcc 2.95.4 and 3.2 generate wrong code for double on intel Date: Mon, 4 Nov 2002 17:02:43 +0000 (GMT) On Mon, 4 Nov 2002, Marco Bernardo wrote: > However, for a person doing research on the formal semantics of programming > languages, it is difficult to accept that two differently compiled versions > of the same sequential program return two different values for the same input. > The compiler should not be free to alter the semantics of a sequential program, > i.e. the program output for a given input! Some consistency should be kept. You should read Norrish's thesis (link from the GCC readings page) which gives a (imperfect) formal model in HOL of the semantics of a subset of C90. There are many areas where the program output for a given input is only partially constrained. -- Joseph S. Myers jsm28@cam.ac.uk