From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10268 invoked by alias); 9 Apr 2002 17:58:08 -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 10261 invoked from network); 9 Apr 2002 17:58:07 -0000 Received: from unknown (HELO localhost.redhat.com) (216.138.202.10) by sources.redhat.com with SMTP; 9 Apr 2002 17:58:07 -0000 Received: from cygnus.com (localhost [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id 56CEE3C90; Tue, 9 Apr 2002 13:58:09 -0400 (EDT) Message-ID: <3CB32BB1.2010007@cygnus.com> Date: Tue, 09 Apr 2002 10:58:00 -0000 From: Andrew Cagney User-Agent: Mozilla/5.0 (X11; U; NetBSD macppc; en-US; rv:0.9.9) Gecko/20020328 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Daniel Berlin Cc: gdb@sources.redhat.com Subject: Re: think-o: dwarf2 CFA != frame->frame (x86-64) References: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2002-04/txt/msg00134.txt.bz2 > On Tue, 9 Apr 2002, Andrew Cagney wrote: > > >> > >> > It might just be misnamed. > >> >> No. DW_OP_fbreg refers explicitly to DW_AT_frame_base. CFA is a >> concept local to the CFI. They would typically evaluate to the same >> value though. > > DW_AT_frame_base is part of the .debug_info section. > This is symbolic debug info, none of which is required to be present in an > executable > On the other hand, the CFA info is required to be present on x86-64, > specifically for the purposes of unwinding the stack. And? > So you can't say that it should use DW_AT_frame_base. It can't. > DW_AT_frame_base is a completely different concept. It is not intended to > have anything to do with unwinding the stack. It also has nothing > necessarily to do with a real frame base. See 3.3.5. This is why it's in > quotes. Most compiler use it in way 1 described in that section, to > simplify location descriptions. (Didn't I point you at 3.3.5? :-). Location expressions use DW_OP_fbreg when they need to refer to the stack. DW_OP_fpreg is defined in terms of DW_AT_frame_base. Can you please point me to the section where a location expression OP directly (not indirectly as in a register) refers to the CFA? > For all intents and purposes, the CFA is the frame base when using dwarf2 > cfi info. If you read my original e-mail, you'll notice that I observed that the two most likely end up having the same value. Andrew