From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29749 invoked by alias); 8 Oct 2013 09:36:14 -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 29697 invoked by uid 48); 8 Oct 2013 09:36:11 -0000 From: "ebotcazou 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 09:36:00 -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: ebotcazou 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: cc 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/msg00443.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54300 Eric Botcazou changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ebotcazou at gcc dot gnu.org --- Comment #10 from Eric Botcazou --- > 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.