From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24529 invoked by alias); 18 Oct 2005 18:46:11 -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 24509 invoked by uid 22791); 18 Oct 2005 18:46:09 -0000 Received: from s142-179-108-108.bc.hsia.telus.net (HELO takamaka.act-europe.fr) (142.179.108.108) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Tue, 18 Oct 2005 18:46:09 +0000 Received: by takamaka.act-europe.fr (Postfix, from userid 507) id 5703247E79; Tue, 18 Oct 2005 11:46:07 -0700 (PDT) Date: Tue, 18 Oct 2005 18:46:00 -0000 From: Joel Brobecker To: gdb-patches@sources.redhat.com Subject: Question regarding storing/restoring data during inferior function call Message-ID: <20051018184607.GO1034@adacore.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4i X-SW-Source: 2005-10/txt/msg00152.txt.bz2 Hello, I'm working on inferior function calls on ia64-hpux (which I'd like to eventually contribute), and I've hit a glitch: HPUX does not allow us to modify the BSP register. So this prevents us from creating a new RSE frame for the function being called. One way around this problem that I thought about was to keep the BSP as is. This meant adjusting a bit the addresses where the arguments were saved. But more importantly, this meant that we overwrote the output section of the register frame. It's pretty easy to add some code in GDB to save this data, either on the inferior stack frame or perhaps directly in debugger memory. However, I don't see a clear way for us to do the restoration. Is there any? Right now, the inferior function call is made AT_ENTRY_POINT. One way to solve my problem that might work is to make the call ON_STACK. Not sure if that's allowed on this chip. But this way, I can dynamically create a small piece of code that does the branch to the target function, which would implicitly cause the BSP update that we're currently doing ourselves. This does open a whole can of worms, though, as I think I'll need to revisit the entire dummy frame unwinder, won't I? Any suggestion? The simplest for me would probably to add an extra mechanism to do associate a restore procedure to the popping of the dummy frame (or something like that), where I believe the registers are restored. Thanks, -- Joel