From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4416 invoked by alias); 8 Oct 2013 09:47:19 -0000 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 Received: (qmail 4378 invoked by uid 48); 8 Oct 2013 09:47:16 -0000 From: "rearnsha at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/54300] [4.7, 4.8, 4.9 Regression] regcprop incorrectly looks through parallel register swap operation Date: Tue, 08 Oct 2013 09:47:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 4.8.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: major X-Bugzilla-Who: rearnsha at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.7.4 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2013-10/txt/msg00445.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54300 --- Comment #11 from Richard Earnshaw --- (In reply to Eric Botcazou from comment #10) > > and regcprop substitues d19 for d18 in insn 27, missing the fact that insn > > 73 is swapping the two values (thus clobbering the old d19 value). > > It's probably fooled by single_set returning the first set of the insn > because of the REG_UNUSED note. I wonder whether it's a generic pitfall of > single_set. Hmm, interesting. Perhaps single_set should not do this if the dead set clobbers an input.