From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 8312 invoked by alias); 25 Apr 2012 15:31:27 -0000 Received: (qmail 8303 invoked by uid 22791); 25 Apr 2012 15:31:26 -0000 X-SWARE-Spam-Status: No, hits=-4.3 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,KHOP_THREADED 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; Wed, 25 Apr 2012 15:31:14 +0000 From: "vermaelen.wouter at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/53117] missed-optimization: worse code for 'x <= 0' compared to 'x < 0' Date: Wed, 25 Apr 2012 15:31:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Keywords: X-Bugzilla-Severity: minor X-Bugzilla-Who: vermaelen.wouter 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: --- 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: 2012-04/txt/msg02275.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53117 --- Comment #3 from Wouter Vermaelen 2012-04-25 15:30:42 UTC --- @Jakub: At first I was puzzled by your comment. But after some investigation I found out that this 'optimization' is indeed not possible when the subtraction would underflow. So you can close this bug report as invalid. (OTOH signed overflow is anyway undefined behavior in C).