From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12628 invoked by alias); 9 Oct 2013 17:48:12 -0000 Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org Received: (qmail 12601 invoked by uid 89); 9 Oct 2013 17:48:12 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-pd0-f175.google.com Received: from mail-pd0-f175.google.com (HELO mail-pd0-f175.google.com) (209.85.192.175) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Wed, 09 Oct 2013 17:48:11 +0000 Received: by mail-pd0-f175.google.com with SMTP id q10so1279019pdj.20 for ; Wed, 09 Oct 2013 10:48:09 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=aVJdSbAeExhDVuTIh2prbpXY/YPzVgZUrZ11CfnyI30=; b=ObmuVyivJUDNDQJB/BIZIG0AjkwcrprJYPrfu5EgCydnJ1I/gkUCCitwsLkxXBtuhV lF07ep+oTltbnWANGcxIZSDJqO5iXibYOa8VTnZ/P2PrE2cAjiETib8x72p4z57dsuNs oOMT8dwfWE4Ym+aMPpPw98T2bjrRAeraZ3yyUbUmUa0/45CWIOPFfX2fgcvTgGZUI47L 39SzqIkWxhCfb/JzPi+b8GQLo21h7xhO6N0ZcJe+vNOJln2Atoz2mC5QJNMoxjyrGQZa YPDLkvLww4wItuF/GGd/yXzCOHcg69ASUkT0eyWTYpOLnKF7SpNe4XfDbSYxJcgsN2Hx +sTQ== X-Gm-Message-State: ALoCoQmbLlrY23Em0xxxdFrYoWuterNEzz22kIXwIfOshxu+swQiLQzfEXGiYRnMcd/SJGvFRZS3kBQXFxEL3vwgGizymMPs3tch8bz1QEhM8Ifi+h+U1onWoyg/J2AvPxPb9RaYGmNZARWRzP7w5YpYDcsJ9Wm//1UFXvu7/Ta6NlAfw2bSYgrj+gESopdz+j5dDBXQUyz0 MIME-Version: 1.0 X-Received: by 10.68.88.161 with SMTP id bh1mr9204478pbb.49.1381340889683; Wed, 09 Oct 2013 10:48:09 -0700 (PDT) Received: by 10.68.66.9 with HTTP; Wed, 9 Oct 2013 10:48:09 -0700 (PDT) In-Reply-To: References: Date: Wed, 09 Oct 2013 17:48:00 -0000 Message-ID: Subject: Re: Crazy compiler optimization From: Ian Lance Taylor To: vijay nag Cc: "gcc-help@gcc.gnu.org" Content-Type: text/plain; charset=ISO-8859-1 X-IsSubscribed: yes X-SW-Source: 2013-10/txt/msg00015.txt.bz2 On Wed, Oct 9, 2013 at 2:36 AM, vijay nag wrote: > > While compiler optimization should guarantee that the result of > execution is same at all optimization levels, That guarantee only holds for programs that fully conform to the language standard and avoid all cases of undefined behaviour. Ian