From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Bignum speedup patch causes crash at startup Date: Tue, 4 Sep 2018 13:48:10 -0700 Organization: UCLA Computer Science Department Message-ID: <20300f3e-3061-2cf6-2431-bdd79d00820f@cs.ucla.edu> References: <86h8j5f33t.fsf@gmail.com> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1536093980 2974 195.159.176.226 (4 Sep 2018 20:46:20 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 4 Sep 2018 20:46:20 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 To: Andy Moreton , emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Sep 04 22:46:16 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fxIDF-0000W6-TU for ged-emacs-devel@m.gmane.org; Tue, 04 Sep 2018 22:46:14 +0200 Original-Received: from localhost ([::1]:52588 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxIFL-0000jS-Uh for ged-emacs-devel@m.gmane.org; Tue, 04 Sep 2018 16:48:23 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:36044) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxIFF-0000jN-ET for emacs-devel@gnu.org; Tue, 04 Sep 2018 16:48:18 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fxIFC-0008ME-4w for emacs-devel@gnu.org; Tue, 04 Sep 2018 16:48:17 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:56298) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fxIFB-0008L4-SC for emacs-devel@gnu.org; Tue, 04 Sep 2018 16:48:14 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 148791616E6; Tue, 4 Sep 2018 13:48:12 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id tFDZYpvh-rgL; Tue, 4 Sep 2018 13:48:11 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 572CD1616E7; Tue, 4 Sep 2018 13:48:11 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id xQGjDv-klMgU; Tue, 4 Sep 2018 13:48:11 -0700 (PDT) Original-Received: from [192.168.1.9] (cpe-23-242-74-103.socal.res.rr.com [23.242.74.103]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 333931616E6; Tue, 4 Sep 2018 13:48:11 -0700 (PDT) In-Reply-To: <86h8j5f33t.fsf@gmail.com> Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 131.179.128.68 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:229265 Archived-At: Andy Moreton wrote: > I now see a strange warning on 64bit Windows (building with gcc 8.2.0 > for target x86_64-w64-mingw32): > > CC data.o > In file included from C:/emacs/git/emacs/master/src/data.c:31: > C:/emacs/git/emacs/master/src/data.c: In function 'arith_driver': > C:/emacs/git/emacs/master/src/lisp.h:2479:34: warning: 'accum' may be used uninitialized in this function [-Wmaybe-uninitialized] > return FIXNUM_OVERFLOW_P (n) ? make_bigint (n) : make_fixnum (n); > ^~~~~~~~~~~~~~~ > C:/emacs/git/emacs/master/src/data.c:2962:12: note: 'accum' was declared here > intmax_t accum = XFIXNUM (val); GCC complains that 'accum' might be used uninitialized even though 'accum's declaration has an initializer? Looks like a clear GCC bug, and might be worth reporting there. For what it's worth I don't observe the problem on RHEL 7 x86-64, building with GCC 8.2.0 (which I built myself for x86_64-pc-linux-gnu) and configuring Emacs with './configure --enable-gcc-warnings --with-gif=no'.