From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10983 invoked by alias); 14 Feb 2014 09:37:57 -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 10948 invoked by uid 48); 14 Feb 2014 09:37:54 -0000 From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/60181] constant folding of complex number incorrect Date: Fri, 14 Feb 2014 09:37:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 4.9.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenth 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-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: 2014-02/txt/msg01295.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60181 --- Comment #2 from Richard Biener --- I think that it needs to be decided on a case-by-case basis whether the runtime complex division routine is "precise enough". But yes, you generally cannot expect constant folding and runtime execution to produce the exact same result. This is FP after all ... (I would expect it for operations that are specified to be rounded correctly to 0.5ulp precision though) Note that the goal we have instead is that cross-compiling from all hosts produces the same constant folding results for a target (code generation doesn't depend on the host).