From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 718 invoked by alias); 11 Apr 2002 23:42:26 -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 679 invoked from network); 11 Apr 2002 23:42:20 -0000 Received: from unknown (HELO localhost.redhat.com) (216.138.202.10) by sources.redhat.com with SMTP; 11 Apr 2002 23:42:20 -0000 Received: from cygnus.com (localhost [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id 1DA513CD1; Thu, 11 Apr 2002 19:42:25 -0400 (EDT) Message-ID: <3CB61F60.6070607@cygnus.com> Date: Thu, 11 Apr 2002 16:42:00 -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: Kevin Buettner Cc: gdb@sources.redhat.com Subject: Re: [rfc] frame->frame => frame->addr && frame->base() References: <3CB5F868.8070001@cygnus.com> <1020411222935.ZM4098@localhost.localdomain> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2002-04/txt/msg00191.txt.bz2 > // High level language concept of the base address of a frame. Often >> refered to as ``frame_base'' or ``frame pointer''. This value should >> only be computed on-demand. It is strongly recommended, though, that >> implementations cache the computed value in the frame cache. The method >> is initialized as part of the frame objects creation. The default >> method returns frame->addr. (see dwarf2 DW_AT_frame_base) >> >> CORE_ADDR (*base) (struct frame_info *frame); > > > This translates the CFA (canonical frame address) into an address that's > useful for some other purpose, right? What are the purposes that it > would be used for? Strictly speaking it doesn't translate a CFA. The CFA is something private to the CFI code. It is just that it happens to evaluate to the same value. In dwarf2, the debug info may indicate that both ->addr and ->base have the value of [r31]+10. > (My worry is that there may be more than one translation which might > prove to be useful.) True. The intent is for dwarf2 where a location expression can contain references to ``fpreg''. That is really a reference to the current value of DW_AT_frame_base. I guess the comment should emphasize how it relates to debug info and the debug ``frame base'' register. Andrew