From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11530 invoked by alias); 25 Jan 2007 21:19:19 -0000 Received: (qmail 11335 invoked by uid 22791); 25 Jan 2007 21:19:16 -0000 X-Spam-Check-By: sourceware.org Received: from mail.codesourcery.com (HELO mail.codesourcery.com) (65.74.133.4) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 25 Jan 2007 21:19:12 +0000 Received: (qmail 23994 invoked from network); 25 Jan 2007 21:19:10 -0000 Received: from unknown (HELO localhost) (jimb@127.0.0.2) by mail.codesourcery.com with ESMTPA; 25 Jan 2007 21:19:10 -0000 To: Joel Brobecker Cc: gdb@sourceware.org Subject: Re: Breaking on C labels? References: <20070125194905.GB4262@adacore.com> From: Jim Blandy Date: Thu, 25 Jan 2007 21:19:00 -0000 In-Reply-To: <20070125194905.GB4262@adacore.com> (Joel Brobecker's message of "Thu, 25 Jan 2007 14:49:05 -0500") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2007-01/txt/msg00326.txt.bz2 Joel Brobecker writes: > A customer asked us a question about the ability of breaking on labels > inside C code. Consider for instance: > > void > procedure foo (void) > { > [...] > error_handler: > [...] > } > > The customer asked if it was possible to break at the error_handler > label. We are helping them with finding alternative solutions, but > I still did a bit of researching... > > I discovered without much surprise that DWARF does indeed have provision > for labels (DW_TAG_label). However, I also noticed that GCC already > generates the associated DIEs. We actually even process them. However, > all my attempts in trying to reference them from the debugger failed. > I tried "break error_handler", or more simply "p error_handler", etc. > > Did we ever make any attempt in implementing this sort of functionality > in the past? > > Looking at the source code, I found in new_symbol (): > > case DW_TAG_label: > attr = dwarf2_attr (die, DW_AT_low_pc, cu); > if (attr) > { > SYMBOL_VALUE_ADDRESS (sym) = DW_ADDR (attr) + baseaddr; > } > SYMBOL_CLASS (sym) = LOC_LABEL; > break; > > So we setup the symbol, but we don't add to any of our symbol lists... > I am left wondering what it is that we'll be doing with this symbol. You're right, it looks to me as if we just throw the symbol away, too. The logical thing would be to put it in the block of the function it's in, since goto labels are block-scoped. It would go in LABEL_DOMAIN, since that's a separate namespace. And then you'd need to teach linespec.[ch] about them.