From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7269 invoked by alias); 22 Jul 2004 00:47:19 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 7262 invoked from network); 22 Jul 2004 00:47:19 -0000 Received: from unknown (HELO nevyn.them.org) (66.93.172.17) by sourceware.org with SMTP; 22 Jul 2004 00:47:19 -0000 Received: from drow by nevyn.them.org with local (Exim 4.34 #1 (Debian)) id 1BnRj3-00076w-LV; Wed, 21 Jul 2004 20:46:21 -0400 Date: Thu, 22 Jul 2004 00:47:00 -0000 From: Daniel Jacobowitz To: Kevin Buettner Cc: gdb-patches@sources.redhat.com, Mark Kettenis , hunt@redhat.com Subject: Re: [RFA] dwarf2-frame.c sign extension patch Message-ID: <20040722004621.GA27215@nevyn.them.org> Mail-Followup-To: Kevin Buettner , gdb-patches@sources.redhat.com, Mark Kettenis , hunt@redhat.com References: <1090350684.3030.10.camel@dragon> <200407212029.i6LKThsR022356@copland.kettenis.dyndns.org> <20040721211723.GA21338@nevyn.them.org> <20040721174136.7eb32412@saguaro> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040721174136.7eb32412@saguaro> User-Agent: Mutt/1.5.5.1+cvs20040105i X-SW-Source: 2004-07/txt/msg00296.txt.bz2 On Wed, Jul 21, 2004 at 05:41:36PM -0700, Kevin Buettner wrote: > On Wed, 21 Jul 2004 17:17:23 -0400 > Daniel Jacobowitz wrote: > > > The rest I have no comment on, but this issue I know... > > > > On Wed, Jul 21, 2004 at 10:29:43PM +0200, Mark Kettenis wrote: > > > (dwarf2_build_frame_info): Set unit.addr_size. > > > > > > Why is the old code wrong? The comment clearly says "from unit > > > header" which is what the DWARF standard says (or at least implies). > > > Theoretically it could change from compilation unit to compilation > > > unit. So I think your change to replace it by > > > TYPE_LENGTH(builtin_type_void_data_ptr) is wrong. > > > > The old code doesn't do it from the compilation unit header either: > > - unit.addr_size = objfile->obfd->arch_info->bits_per_address / 8; > > + unit.addr_size = TYPE_LENGTH (builtin_type_void_data_ptr); > > > > Any use of bits_per_address, IMO, is a bug. Take a look at how this > > field is set on MIPS; it's based on the architecture, not the ABI or > > the pointer size or the dwarf address size or anything like that. > > I agree. > > > TYPE_LENGTH doesn't seem like an ideal replacement. Can we use the > > value in the compilation unit header here? > > I considered doing this, but was told that the information in > .debug_frame should be independent of the CU header. I really > don't know what the "right" solution is. Oh, right, we're in .debug_frame here. I care very much about being .able to use .debug_frame without .debug_info. Debian distributes library images with only .debug_frame, to provide backtraces. .debug_frame doesn't provide this information. That's a known defect; I think that Jim proposed correcting it on the dwarf2 list. Does anyone know if .eh_frame solves this problem somehow? Otherwise, I think that using TYPE_LENGTH (with a big comment explaining the issue) may be the best we can do. -- Daniel Jacobowitz