From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18216 invoked by alias); 26 Jan 2012 18:42:52 -0000 Received: (qmail 18206 invoked by uid 22791); 26 Jan 2012 18:42:51 -0000 X-SWARE-Spam-Status: No, hits=-2.8 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,TW_ZJ 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; Thu, 26 Jan 2012 18:42:39 +0000 From: "ubizjak at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/51994] [4.6/4.7 Regression] git-1.7.8.3 miscompiled due to negative bitpos from get_inner_reference Date: Thu, 26 Jan 2012 20:40:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: middle-end X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: ubizjak at gmail dot com X-Bugzilla-Status: NEW X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.6.3 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/msg03061.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51994 --- Comment #22 from Uros Bizjak 2012-01-26 18:41:57 UTC --- (In reply to comment #20) > I agree that making get_inner_reference artificially return a non-zero poffset > would most certainly be problematic as this would change the semantics. But > it's also clear that the lower level bit-field manipulation routines aren't > really prepared to deal with negative stuff. So I think that we shouldn't > change the prototypes of these routines, but instead patch up callers that > forward the values returned by get_inner_reference to these routines. > > Adding assertions in these routines could indeed help. I have added these. But.. could you please take the fix to this problem further?