From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3990 invoked by alias); 16 Jan 2008 00:50:17 -0000 Received: (qmail 3744 invoked by alias); 16 Jan 2008 00:49:34 -0000 Date: Wed, 16 Jan 2008 01:53:00 -0000 Message-ID: <20080116004934.3742.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug c/34803] wrong code for dereferencing type-punned pointer In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "gin at mo dot msk dot ru" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2008-01/txt/msg01573.txt.bz2 ------- Comment #3 from gin at mo dot msk dot ru 2008-01-16 00:49 ------- Subject: Re: wrong code for dereferencing type-punned pointer > obviously violating c aliasing rules here. Certainly. Was quite explicit about that: That is, `-fno-strict-aliasing' no longer disables optimizations that require strict aliasing rules in code. To reproduce compiler (still) doing such an optimizations (and breaking code), one has to violate aliasing rules. Also confirming that one may factor these separate issues in the report. . Compiler ignores `-fno-strict-aliasing'. Expecting that can violate aliasing rules, and tell compiler to allow that, by passing this option. The expectation is based on both option documentation and earlier gcc versions actually doing so. . Warning not issued, even when compiler does optimizations that require code to conform to c strictest aliasing rules. On request will confine this bug database entry to one of them, and post another issue as separate bug database entry. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34803