From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27564 invoked by alias); 17 Mar 2003 00:09:10 -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 27535 invoked from network); 17 Mar 2003 00:09:09 -0000 Received: from unknown (HELO localhost.redhat.com) (66.30.197.194) by sources.redhat.com with SMTP; 17 Mar 2003 00:09:09 -0000 Received: from redhat.com (localhost [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id 3724D2B11; Sun, 16 Mar 2003 19:09:03 -0500 (EST) Message-ID: <3E75121F.4030405@redhat.com> Date: Mon, 17 Mar 2003 00:09:00 -0000 From: Andrew Cagney User-Agent: Mozilla/5.0 (X11; U; NetBSD macppc; en-US; rv:1.0.2) Gecko/20030223 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Daniel Jacobowitz Cc: gdb@sources.redhat.com Subject: Re: frame->unwind->this_base() References: <3E74F4F4.50003@redhat.com> <20030316221008.GA19037@nevyn.them.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2003-03/txt/msg00241.txt.bz2 > On Sun, Mar 16, 2003 at 05:04:36PM -0500, Andrew Cagney wrote: > >> At present there is a per-frame ID method since different frames >> determine their ID using different techniques. The ID (which identifies >> a given frame instance) includes a base and pc/func value. >> >> GDB's frame code also makes available the get_frame_base() method. >> While the default implementation returns get_frame_id().base, I think >> there is going to need to be a per-frame frame->unwind->this_base method. >> >> For dwarf2 frames, it would return, DW_AT_frame_base. For prologue >> frames, it would return an attempt at an equivalent value. Hopefully it >> wouldn't be called for other frame types :-). >> >> It might even be reasonable for a prologue based unwinder to error out >> when asked for the frame's base before the stack frame has been created. >> >> Thoughts? >> >> I should note that dwarf2expr.c contains code that tries to >> locally/directly evaluate the frame base. I think that should instead >> do a get_frame_base() call. > > > There's no guarantee right now that the DW_AT_frame_base agrees with > the frame's base. I don't even think it's necessary that they be the > same. There is certainly no guarentee that the DW_AT_frame_base and `struct frame_id.base' match. However, shouldn't the only thing needing the `virtual frame pointer' / get_frame_base() be the code that needs a virtual base pointer when computing the value of a local variable? Andrew