From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15317 invoked by alias); 21 Oct 2010 15:39:13 -0000 Received: (qmail 15307 invoked by uid 22791); 21 Oct 2010 15:39:10 -0000 X-SWARE-Spam-Status: No, hits=-1.7 required=5.0 tests=AWL,BAYES_00,MSGID_FROM_MTA_HEADER,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mtagate3.de.ibm.com (HELO mtagate3.de.ibm.com) (195.212.17.163) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 21 Oct 2010 15:39:03 +0000 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate3.de.ibm.com (8.13.1/8.13.1) with ESMTP id o9LFcx6Q031470 for ; Thu, 21 Oct 2010 15:38:59 GMT Received: from d12av02.megacenter.de.ibm.com (d12av02.megacenter.de.ibm.com [9.149.165.228]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o9LFd0wV3006642 for ; Thu, 21 Oct 2010 17:39:00 +0200 Received: from d12av02.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av02.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id o9LFcxc2018394 for ; Thu, 21 Oct 2010 17:38:59 +0200 Received: from tuxmaker.boeblingen.de.ibm.com (tuxmaker.boeblingen.de.ibm.com [9.152.85.9]) by d12av02.megacenter.de.ibm.com (8.12.11.20060308/8.12.11) with SMTP id o9LFcwo1018357; Thu, 21 Oct 2010 17:38:58 +0200 Message-Id: <201010211538.o9LFcwo1018357@d12av02.megacenter.de.ibm.com> Received: by tuxmaker.boeblingen.de.ibm.com (sSMTP sendmail emulation); Thu, 21 Oct 2010 17:38:58 +0200 Subject: Re: [rfc/rfa] Use ARM exception tables as GDB unwinder To: matthew.gretton-dann@arm.com (Matthew Gretton-Dann) Date: Thu, 21 Oct 2010 15:39:00 -0000 From: "Ulrich Weigand" Cc: gdb-patches@sourceware.org, rearnsha@arm.com, dan@codesourcery.com In-Reply-To: <1287573257.3073.26.camel@e102319-lin.cambridge.arm.com> from "Matthew Gretton-Dann" at Oct 20, 2010 12:14:17 PM MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2010-10/txt/msg00335.txt.bz2 Matthew Gretton-Dann wrote: > Firstly an apology - I'm not going to be able to look at this in detail > for a while, and Richard Earnshaw is away as well for a couple of weeks. No problem, thanks for looking at this patch! > One of the 'optimisations' that can be applied to the exception unwind > table is that if two contiguous functions have the same unwind tables > they can be merged. [snip] > Can the change you detail above handle this? That depends on whether there is symbol information for those functions. If there *is* a symbol for the second function, my patch would detect that the symbol is closer than the unwind start address, in which case it would refuse to use unwind data, and fall back to prologue parsing. If there is no symbol, the patch would use the function start address from the unwind information as part of the frame ID, which isn't really correct. On the other hand, since there is no symbol, we don't *know* the real start address either ... Using the address from unwind data seems as good as anything else that we could possibly do here. Bye, Ulrich -- Dr. Ulrich Weigand GNU Toolchain for Linux on System z and Cell BE Ulrich.Weigand@de.ibm.com