From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6228 invoked by alias); 26 Jan 2012 07:57:29 -0000 Received: (qmail 6218 invoked by uid 22791); 26 Jan 2012 07:57:27 -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 07:57:12 +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 09:31:00 -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/msg03010.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51994 --- Comment #16 from Uros Bizjak 2012-01-26 07:57:10 UTC --- (In reply to comment #15) > Can't most of the callers of get_inner_reference cope with negative bitpos > though? If so, perhaps only the caller or two in the expansion which doesn't > should be adjusted. I did look a bit for other uses, and negative offsets can result in subregs with negative index and shifts with negative shift constant (see i.e. fold-const.c, line 3454). So, I still think that infrastructure doesn't handle negative bit positions well.