From owner-freebsd-hackers@FreeBSD.ORG  Fri Aug 29 16:46:37 2003
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id C624D16A4BF
	for <hackers@freebsd.org>; Fri, 29 Aug 2003 16:46:37 -0700 (PDT)
Received: from kientzle.com (h-66-166-149-50.SNVACAID.covad.net
	[66.166.149.50])
	by mx1.FreeBSD.org (Postfix) with ESMTP id CA3B243FDD
	for <hackers@freebsd.org>; Fri, 29 Aug 2003 16:46:36 -0700 (PDT)
	(envelope-from kientzle@acm.org)
Received: from acm.org (big.x.kientzle.com [66.166.149.54])
	by kientzle.com (8.12.9/8.12.9) with ESMTP id h7TNkZsE070326;
	Fri, 29 Aug 2003 16:46:36 -0700 (PDT)
	(envelope-from kientzle@acm.org)
Message-ID: <3F4FE60B.1050002@acm.org>
Date: Fri, 29 Aug 2003 16:47:23 -0700
From: Tim Kientzle <kientzle@acm.org>
User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.3.1) Gecko/20030524
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: Pav Lucistnik <pav@oook.cz>
References: <1062195438.641.18.camel@hood.oook.cz>
In-Reply-To: <1062195438.641.18.camel@hood.oook.cz>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
cc: hackers@freebsd.org
Subject: Re: gcc weirdness
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
Reply-To: kientzle@acm.org
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 29 Aug 2003 23:46:37 -0000

Pav Lucistnik wrote:
> What am I missing here?
> 
> Let we have a function called popup(). Inside this function there is
> this code:
> 
> list = get_children(ds, x, TYPE_ELEMENT);
> 
> gdb shows these values:
> 
> (gdb) print ds
> $46 = (Type *) 0x1
> 
> (gdb) print x
> $47 = 0x86adb80
> 
> So far, everything is fine. Now, let step down one frame in gdb:
> 
> (gdb) down
> #5 0x0808b807 in get_children(ds=0x86adb80, node=0x1, tag_type=TYPE_E...
> 
> In the source, there is a
> 
> GList* get_children (Type* ds, PtrNode node, enum Types tag_type) {
> 
> Do you see ds and node values swapped? The program crashes because of
> this swapping. What is wrong? I use gcc-3.3.1 on today's -CURRENT.
> 

First, try putting printf() statements at the beginning of
get_children and just before the corresponding call to see
if that's really what's going on.

I presume you're seeing this while debugging a core dump after
a crash?  The crash may have mangled the stack, in which case,
gdb may not be correctly identifying the function arguments.

Tim