From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4566 invoked by alias); 26 Apr 2013 07:07:25 -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 4513 invoked by uid 48); 26 Apr 2013 07:07:22 -0000 From: "burnus at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug fortran/57071] Optimize (-1)**k to 1 - 2 * mod(K, 2) Date: Fri, 26 Apr 2013 07:07:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: fortran X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: burnus at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED 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 X-SW-Source: 2013-04/txt/msg02136.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57071 --- Comment #3 from Tobias Burnus 2013-04-26 07:07:22 UTC --- As James Van Buskirk pointed out, the algorithm will fail if k < 0. Thus, he suggests, which gives the expected result: 1 - ISHFT(IAND(K,1),1)