From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12247 invoked by alias); 9 Mar 2010 18:54:16 -0000 Received: (qmail 12239 invoked by uid 22791); 9 Mar 2010 18:54:15 -0000 X-SWARE-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from mail2.rz.htw-berlin.de (HELO mail2.rz.htw-berlin.de) (141.45.10.102) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 09 Mar 2010 18:54:09 +0000 Envelope-to: gcc-help@gcc.gnu.org Received: from e178085094.adsl.alicedsl.de ([85.178.85.94] helo=[192.168.178.2]) by mail2.rz.htw-berlin.de with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.68 (FreeBSD)) (envelope-from ) id 1Np4ZC-0006jj-VB for gcc-help@gcc.gnu.org; Tue, 09 Mar 2010 19:54:07 +0100 Message-ID: <4B96994D.40904@htw-berlin.de> Date: Tue, 09 Mar 2010 18:54:00 -0000 From: Thomas Martitz Reply-To: thomas.martitz@student.htw-berlin.de User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.8) Gecko/20100307 Icedove/3.0.3 MIME-Version: 1.0 To: gcc-help@gcc.gnu.org Subject: Re: Problems migrating to gcc 4.4.3&eabi - apparently a gcc bug References: <4B9677C1.6040502@htw-berlin.de> <4B967A4D.8060905@redhat.com> <4B968150.8010004@htw-berlin.de> <4B96953E.10305@redhat.com> In-Reply-To: <4B96953E.10305@redhat.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit X-HTW-SPAMINFO: this message was scanned by eXpurgate (http://www.eleven.de) X-IsSubscribed: yes 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 X-SW-Source: 2010-03/txt/msg00121.txt.bz2 Am 09.03.2010 19:36, schrieb Andrew Haley: > That does not surprise me. I think you're seeing a problem that is > caused by something elsewhere in your program. I'm guessing that > there may be a bad prototype or somesuch. > > I think you need to strip down your sources until you find something. > > Maybe you should try -save-temps and have a look at the actual > preprocessd source. Maybe some bastard has done > > #define int long > > or something evil like that! > > Andrew. > No, I know our codebase pretty well. This is not the problem. Not that int or long matters, anyway. In the mean time we found a test case: ---- void foo(int last, char * block); void bar(void) { struct { char * __attribute__((aligned(8))) member; } s; foo(0,s.member); } ---- compiled with arm-elf-eabi-gcc -c test.c This example exposes the problem. We found the problem is related to struct addressing and the aligned attribute. - normal stack variables work - struct members work with __attribute__((aligned(4))) - struct members with __attribute__((aligned(X))) where X >= 8 *do not* work. Look at the assembly output for this very example. block is passed in r2, while it's supposed to be passed in r1. Our temporary "fix" is to make it "void foo(int last, volatile char * block);" [notice the volatile keyword] and it works as well (block passed in r1). This is definitely a gcc bug. The generated call is dependent on the parameter passed. The callee can't know about this. And it also happens with -O0. Best regards.