From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Juanma Barranquero" Newsgroups: gmane.emacs.bugs Subject: bug#1448: 23.0.60; update to cvs emacs crash report Date: Fri, 28 Nov 2008 12:23:33 +0100 Message-ID: References: <81hc5s5t2y.fsf@blackmagic-design.com> Reply-To: Juanma Barranquero , 1448@emacsbugs.donarmstrong.com NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1227871912 17403 80.91.229.12 (28 Nov 2008 11:31:52 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 28 Nov 2008 11:31:52 +0000 (UTC) Cc: Feng li , 1448@emacsbugs.donarmstrong.com To: "Eli Zaretskii" Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Fri Nov 28 12:32:47 2008 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 4.50) id 1L61aX-00079W-0G for geb-bug-gnu-emacs@m.gmane.org; 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Fri, 28 Nov 2008 03:23:33 -0800 (PST) In-Reply-To: Content-Disposition: inline X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6 (newer, 3) Resent-Date: Fri, 28 Nov 2008 06:30:51 -0500 X-BeenThere: bug-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list 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:22737 Archived-At: On Fri, Nov 28, 2008 at 11:56, Eli Zaretskii wrote: > How does "C-h b" get to display unibyte or composed characters? In a keymap case I found, Emacs crashed while trying to display \200. But I could be wrong (again) about what exactly triggers the crash. > Is it a Heisenbug? i.e., does it disappear if you add printf's around > the code that crashes or in its callers? Not exactly a heisenbug, because it does not disappear. It moves. That's why I've said that it always fails with draw_glyphs in the stack, but not always in fill_glyph_string. > If the bug stays put when code around it is modified, you could try > debugging it by adding "if (something) abort ();" lines testing > various conditions that are suspect of causing the crash. I've tried that (well, I added xassert() and/or eassert) at likely places; they didn't get triggered. > However, `s' is dereferenced many times in `fill_glyph_string' before > it gets to line 19740, so I think GDB lies about the place where it > crashed (because GCC optimizes code to the degree that any relation > between the code and the source lines is lost). Yes, I agree that GDB lies. If only the bug happened with non-optimized code... > Therefore, the first thing to do is disassembly the vicinity of the > crash locus (0x0101fdd5) and see which code, exactly, crashes, and > why. Disassembly should establish (1) the source line that crashes, > and (2) which C-level variable causes the crash. I'll try to do that. > Note that `s' is allocated via `alloca' in BUILD_CHAR_GLYPH_STRINGS, > which is called by BUILD_GLYPH_STRINGS, which in turn is called by > `draw_glyphs' at line 20332 in frame #1: Sorry, I fail to understand what you are trying to say. I've suspected that alloca'd memory is related to the crash, but I don't see how. Juanma