From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2498 invoked by alias); 5 May 2003 14:52:57 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 2491 invoked from network); 5 May 2003 14:52:57 -0000 Received: from unknown (HELO localhost.redhat.com) (207.219.125.105) by sources.redhat.com with SMTP; 5 May 2003 14:52:57 -0000 Received: from redhat.com (localhost [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id 241A32B2F; Mon, 5 May 2003 10:52:54 -0400 (EDT) Message-ID: <3EB67AC6.2050407@redhat.com> Date: Mon, 05 May 2003 14:52:00 -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: Mark Kettenis , gdb-patches@sources.redhat.com Subject: Re: [PATCH/i386newframe/RFC] DWARF CFI frame unwinder References: <200305042207.h44M7gNG023734@elgar.kettenis.dyndns.org> <3EB5DBFF.6030009@redhat.com> <20030505034242.GA21263@nevyn.them.org> <3EB67056.4070209@redhat.com> <20030505142705.GA28866@nevyn.them.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2003-05/txt/msg00065.txt.bz2 >> >The frame's CFA is the basis for identifying the frame and locating >> >saved registers in the CFI. It is always present when you have CFI. >> > >> >DW_AT_frame_base is the basis for locating saved variables and locals. >> >It is generally present when you have DWARF-2 debug info. > >> >> You and I went through all this not too long ago. frame-base is for >> this high level thingie, frame-unwind is for the low level register >> information. > > > Then, as Mark said, it shouldn't be providing a frame base at all. The > CFA information is not the right frame base, and the use of > DW_AT_frame_base is exactly orthogonal to the use of CFI. Daniel, you and I went through all this not too long ago. Not providing a dwarf2 specific frame-base (returning DW_AT_frame_base) leads to ``info frame'' printing inconsistent information. It will report ``id.stack_addr'' as the frame's base and that is definitly not correct - it won't match the high level ``base'' that the user expects to match a disassembler. Again, this is why the high level frame-base is separate to the low level frame-unwind. It is possible to mix 'n' match. However, it doesn't need to be implemented right now - at present dwarf2loc short circutes frame-base, implementing DW_AT_frame_base locally. Andrew