Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ihlpf!nevin1 From: nevin1@ihlpf.ATT.COM (00704A-Liber) Newsgroups: comp.lang.c Subject: Re: Pragmas Message-ID: <3313@ihlpf.ATT.COM> Date: 9 Jan 88 01:07:19 GMT References: <17196@topaz.rutgers.edu> <6920@brl-smoke.ARPA> <14460@think.UUCP> Reply-To: nevin1@ihlpf.UUCP (00704A-Liber,N.) Organization: AT&T Bell Laboratories - Naperville, Illinois Lines: 20 In article <14460@think.UUCP> barmar@sauron.think.com.UUCP (Barry Margolin) writes: >[some stuff deleted]. Any program >that behaves differently depending on whether a variable was declared >with noalias has a bug. The standard doesn't specify the >virtual-machine semantics of broken programs, only correct programs. I agree. However, suppose I compile a program that uses 'noalias' with a compiler that ignores 'noalias'. I test it and find no problems. I now have a program which I believe works but if ported to a compiler which uses 'noalias' it might develop a bug. I believe that all programs which will conform to the ANSI C standard should run equivalently under all compilers that conform to ANSI C. (I do not believe that ANSI requires a compiler writer to implement the optimizations that can be made with the use of noalias.) With noalias, this cannot be assured. -- _ __ NEVIN J. LIBER ..!ihnp4!ihlpf!nevin1 (312) 510-6194 ' ) ) "The secret compartment of my ring I fill / / _ , __o ____ with an Underdog super-energy pill." / (_