From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3105 invoked by alias); 27 Jan 2012 22:39:48 -0000 Received: (qmail 3095 invoked by uid 22791); 27 Jan 2012 22:39:47 -0000 X-SWARE-Spam-Status: No, hits=-2.9 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 27 Jan 2012 22:39:34 +0000 From: "bruno at clisp dot org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/52023] _Alignof (double) yields wrong value on x86 Date: Fri, 27 Jan 2012 23:12:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: bruno at clisp dot org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 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: 2012-01/txt/msg03221.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023 --- Comment #9 from bruno at clisp dot org 2012-01-27 22:39:01 UTC --- (In reply to comment #7) > What happens if you have the attribute packed on the structure? Attribute 'packed' is outside the scope of ISO C11. We're discussing ISO C11 compliant programs here. ISO C11 has the _Alignas keyword, with which a stricter alignment can be requested (ISO C11 6.2.8.(1), 6.7.5.(4)), but not a less strict alignment. GCC's __alignof__ that returns the *preferred* alignment of an object of the given type has its uses (in memory allocators for example). But the semantics imposed by ISO C11 on the 'alignof' and '_Alignof' operators defined through is address boundary requirement for all "objects" of that type, not the preferred alignment.