From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7652 invoked by alias); 23 Nov 2005 03:14:59 -0000 Received: (qmail 7644 invoked by uid 22791); 23 Nov 2005 03:14:58 -0000 X-Spam-Check-By: sourceware.org Received: from zproxy.gmail.com (HELO zproxy.gmail.com) (64.233.162.193) by sourceware.org (qpsmtpd/0.31) with ESMTP; Wed, 23 Nov 2005 03:14:58 +0000 Received: by zproxy.gmail.com with SMTP id x3so1291139nzd for ; Tue, 22 Nov 2005 19:14:56 -0800 (PST) Received: by 10.36.147.1 with SMTP id u1mr4509239nzd; Tue, 22 Nov 2005 19:14:56 -0800 (PST) Received: by 10.37.2.35 with HTTP; Tue, 22 Nov 2005 19:14:56 -0800 (PST) Message-ID: <8f2776cb0511221914h7858170cp6bd2d66382d4ec1f@mail.gmail.com> Date: Wed, 23 Nov 2005 03:52:00 -0000 From: Jim Blandy To: Joel Brobecker Subject: Re: Prologue analysis interface Cc: gdb@sourceware.org In-Reply-To: <20051123022325.GU1635@adacore.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <8f2776cb0511221124u988f759u17418a114e1f3b7c@mail.gmail.com> <20051122193034.GA25326@nevyn.them.org> <8f2776cb0511221549p2cfbbc30w621da6c2f159a33f@mail.gmail.com> <20051123020455.GA2247@nevyn.them.org> <20051123022325.GU1635@adacore.com> X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2005-11/txt/msg00518.txt.bz2 On 11/22/05, Joel Brobecker wrote: > > The frame pointer bits do involve some target heuristics. I think we > > could do away with that, if we had reason to (i.e. an interesting > > target which didn't use a fixed register for this). But I'm not > > suggesting it until we have such a target, hopefully not for a long > > time. > > Not sure if this is relevant, but the HPPA ABI says that when there > is a frame pointer, it is either in r3 or r4, depending on the frame > size (IIRC). GCC doesn't follow the ABI, and always uses r3, but I am > pretty sure that the HP C compiler does follow that convention... The MIPS (if I recall, the first architecture to give us real headaches in prologue analysis, before it became popular, things were pretty simple and the current approach worked pretty well) doesn't designate a particular register for use as a frame pointer, either. I think all we really need to know is how to find the original SP (for use as the CFA). Having a designated frame pointer narrows the set of places we need to look, but we could search all the registers for something with the right value.