From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3144 invoked by alias); 31 Jan 2003 22:00:04 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 3088 invoked from network); 31 Jan 2003 22:00:01 -0000 Received: from unknown (HELO localhost.redhat.com) (172.16.49.200) by 172.16.49.205 with SMTP; 31 Jan 2003 22:00:01 -0000 Received: from redhat.com (localhost [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id 1119D3C9D; Fri, 31 Jan 2003 16:59:57 -0500 (EST) Message-ID: <3E3AF1DC.3040706@redhat.com> Date: Fri, 31 Jan 2003 22:00:00 -0000 From: Andrew Cagney User-Agent: Mozilla/5.0 (X11; U; NetBSD macppc; en-US; rv:1.0.1) Gecko/20021211 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Daniel Jacobowitz Cc: gdb@sources.redhat.com, Jim Blandy , Kevin Buettner Subject: Re: DWARF-2 and address sizes References: <20030131213034.GA2545@nevyn.them.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2003-01/txt/msg00538.txt.bz2 > [Kevin, I noticed you doing some work in this area re S/390, maybe you've > got a comment? Anyone else? I'm grasping at straws.] > > I'm trying to figure out how to handle addresses in the DWARF expression > evaluator. First consider DW_OP_deref: the following data is "the size of > an address on the target machine", which I would personally take to mean > cu_header->addr_size. Is this ever different from TARGET_ADDRESS_BIT / > TARGET_CHAR_BIT, which is what Daniel was originally using? I can imagine architectures wack-o enough for cu_header->addr_size != TARGET_ADDRESS_BIT / TARGET_CHAR_BIT. Someone doing a 16 bit port using 32 bit elf. But I don't think you'll encounter a case where cu_header->addr_size isn't locally consistent with the rest of the file. > Do we have to > worry about a binary in which different compilation units (or different > shared objects, even) have a different value for this? See if binutils allows it. If not ... > If the consensus is "no, that's too stupid to be allowed to live", then this > gets much easier. > > (Then consider DW_OP_deref_size; this is a fun one, since it has to be > zero-extended to the size of an address on the target machine according to > the spec, and then in GDB it may have to be zero or sign extended to the > size of a CORE_ADDR for storage. I haven't tested any of this on MIPS yet > and I don't want to, damn it. I don't know of any MIPS ABI with multiple > pointer sizes, and you can't link different ABIs, so encountering > DW_OP_deref_size is probably impossible. I hope.) Have a look at dwarf2read.c:read_address() the existing code already handles one case of this. Andrew