From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 88810 invoked by alias); 21 Jul 2015 13:42:31 -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 88151 invoked by uid 48); 21 Jul 2015 13:42:26 -0000 From: "wdijkstr at arm dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/66946] Spurious uninitialized warning Date: Tue, 21 Jul 2015 13:42:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 6.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: wdijkstr at arm dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: 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: 2015-07/txt/msg01811.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66946 --- Comment #4 from Wilco --- (In reply to Andrew Pinski from comment #2) > Comment on attachment 36021 [details] > minimal example > > written == ((wchar_t) 0xfffd) > > Will ever be true or is there some sign extending going on which causes this > to be false for the default case? The issue seems related to signextension indeed. My GCC builds include this patch: https://gcc.gnu.org/ml/gcc-patches/2015-05/msg00005.html When I disable this new phase the warning disappears, so it might be due to a transformation it makes. The generated code is virtually identical, just different register allocation.