From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 32214 invoked by alias); 22 Apr 2003 23:53:06 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 32201 invoked from network); 22 Apr 2003 23:53:05 -0000 Received: from unknown (HELO lacrosse.corp.redhat.com) (66.187.233.200) by sources.redhat.com with SMTP; 22 Apr 2003 23:53:05 -0000 Received: from localhost.localdomain (dhcp-172-16-25-221.sfbay.redhat.com [172.16.25.221]) by lacrosse.corp.redhat.com (8.11.6/8.9.3) with ESMTP id h3MNq4V02966; Tue, 22 Apr 2003 19:52:04 -0400 Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by localhost.localdomain (8.12.8/8.12.8) with ESMTP id h3MNplNT006805; Tue, 22 Apr 2003 16:51:47 -0700 Received: (from aoliva@localhost) by localhost.localdomain (8.12.8/8.12.8/Submit) id h3MNpl2U006800; Tue, 22 Apr 2003 16:51:47 -0700 To: kenner@vlsi1.ultra.nyu.edu (Richard Kenner) Cc: gcc-patches@gcc.gnu.org, gcc@gcc.gnu.org Subject: Re: DATA_ALIGNMENT vs. DECL_USER_ALIGNMENT References: <10304221140.AA05299@vlsi1.ultra.nyu.edu> From: Alexandre Oliva Organization: GCC Team, Red Hat Date: Wed, 23 Apr 2003 01:07:00 -0000 In-Reply-To: <10304221140.AA05299@vlsi1.ultra.nyu.edu> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SW-Source: 2003-04/txt/msg01107.txt.bz2 On Apr 22, 2003, kenner@vlsi1.ultra.nyu.edu (Richard Kenner) wrote: > But the compiler can't tell whether, when you specify alignment for a > type, you mean for interface or for efficiency, so I think it > shouldn't make an assumption that it's to be used only for the former > case like you seem to believe it should do. > No, I don't believe that, but it's not relevant. Because it *might* > have been meant for interface, the compiler is not allowed to change > the alignment of types. The point is that you're saying it could increase the alignment of an object in spite of a user-specified alignment for its type. You can't tell whether the alignment was defined for interface, space or performance, so a user-specified alignment for a type should be obeyed. -- Alexandre Oliva Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/ Red Hat GCC Developer aoliva@{redhat.com, gcc.gnu.org} CS PhD student at IC-Unicamp oliva@{lsd.ic.unicamp.br, gnu.org} Free Software Evangelist Professional serial bug killer