From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Andreas Schwab Newsgroups: gmane.emacs.bugs Subject: bug#5754: Bytecomp Arithmetic test failed Date: Sun, 04 Apr 2010 10:05:03 +0200 Message-ID: References: <87ocifjx74.fsf@mail.jurta.org> <87iq88ma6c.fsf@stupidchicken.com> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: dough.gmane.org 1270369615 16060 80.91.229.12 (4 Apr 2010 08:26:55 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Sun, 4 Apr 2010 08:26:55 +0000 (UTC) Cc: 5754@debbugs.gnu.org To: Chong Yidong Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Sun Apr 04 10:26:51 2010 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1NyLAP-0002np-Go for geb-bug-gnu-emacs@m.gmane.org; Sun, 04 Apr 2010 10:26:49 +0200 Original-Received: from localhost ([127.0.0.1]:37676 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NyLAO-0007Ji-S5 for geb-bug-gnu-emacs@m.gmane.org; Sun, 04 Apr 2010 04:26:48 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NyL9p-0005YV-MQ for bug-gnu-emacs@gnu.org; Sun, 04 Apr 2010 04:26:13 -0400 Original-Received: from [140.186.70.92] (port=37291 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NyL9k-0005EC-Da for bug-gnu-emacs@gnu.org; Sun, 04 Apr 2010 04:26:13 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1NyL9d-0006cC-87 for bug-gnu-emacs@gnu.org; Sun, 04 Apr 2010 04:26:08 -0400 Original-Received: from debbugs.gnu.org ([140.186.70.43]:33108) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1NyL9c-0006bv-Ma for bug-gnu-emacs@gnu.org; Sun, 04 Apr 2010 04:26:00 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.69) (envelope-from ) id 1NyKqI-0004QH-7S; Sun, 04 Apr 2010 04:06:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Andreas Schwab Original-Sender: debbugs-submit-bounces@debbugs.gnu.org Resent-To: owner@debbugs.gnu.org Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sun, 04 Apr 2010 08:06:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 5754 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 5754-submit@debbugs.gnu.org id=B5754.127036830616990 (code B ref 5754); Sun, 04 Apr 2010 08:06:02 +0000 Original-Received: (at 5754) by debbugs.gnu.org; 4 Apr 2010 08:05:06 +0000 Original-Received: from localhost ([127.0.0.1] helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1NyKpN-0004Pz-Jo for submit@debbugs.gnu.org; Sun, 04 Apr 2010 04:05:05 -0400 Original-Received: from mail-out.m-online.net ([212.18.0.9]) by debbugs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1NyKpL-0004Pe-L6 for 5754@debbugs.gnu.org; Sun, 04 Apr 2010 04:05:04 -0400 Original-Received: from mail01.m-online.net (mail.m-online.net [192.168.3.149]) by mail-out.m-online.net (Postfix) with ESMTP id EB1BB1C1538C; Sun, 4 Apr 2010 10:04:58 +0200 (CEST) X-Auth-Info: gQyQYVq0DRVdEOHHUjlf/BArlHxS3/RJ3UD+hi8HVN0= Original-Received: from whitebox.home (ppp-88-217-107-122.dynamic.mnet-online.de [88.217.107.122]) by mail.mnet-online.de (Postfix) with ESMTP id ADB439053E; Sun, 4 Apr 2010 10:04:58 +0200 (CEST) Original-Received: by whitebox.home (Postfix, from userid 501) id AA50A1E5397; Sun, 4 Apr 2010 10:05:04 +0200 (CEST) X-Yow: NOW do I get to blow out the CANDLES?? In-Reply-To: <87iq88ma6c.fsf@stupidchicken.com> (Chong Yidong's message of "Sat, 03 Apr 2010 18:40:59 -0400") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1.95 (gnu/linux) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.11 Precedence: list Resent-Date: Sun, 04 Apr 2010 04:06:02 -0400 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:35919 Archived-At: Chong Yidong writes: > The key is that if I compile Emacs with CFLAGS="-g", then > > (funcall > (byte-compile > (list 'lambda nil > (quote (let ((a (expt 2 -1074)) (b 0.125)) (* a 8 b)))))) > > returns 0.0. If I compile Emacs with CFLAGS="-g -O2", then it returns > 5e-324. > > It looks like this may be a compiler bug. It's most likely the effect of excess precision, due to floating point values being held in registers instead of reloaded from memory. Try -ffloat-store. Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different."