From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26414 invoked by alias); 1 Dec 2004 21:25:04 -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 26364 invoked from network); 1 Dec 2004 21:25:00 -0000 Received: from unknown (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org with SMTP; 1 Dec 2004 21:25:00 -0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.12.11/8.12.11) with ESMTP id iB1LOsqt018631 for ; Wed, 1 Dec 2004 16:24:55 -0500 Received: from localhost.redhat.com (vpn50-50.rdu.redhat.com [172.16.50.50]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id iB1LOsr05091; Wed, 1 Dec 2004 16:24:54 -0500 Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id B7615129D8C; Wed, 1 Dec 2004 16:23:49 -0500 (EST) Message-ID: <41AE3664.9010306@gnu.org> Date: Wed, 01 Dec 2004 21:25:00 -0000 From: Andrew Cagney User-Agent: Mozilla Thunderbird 0.8 (X11/20041020) MIME-Version: 1.0 To: Daniel Jacobowitz Cc: Randolph Chung , gdb-patches@sources.redhat.com Subject: Re: [patch/RFA] multiarch INSTRUCTION_NULLIFIED References: <419CB118.7080401@gnu.org> <20041118162108.GK15714@tausq.org> <200411181655.iAIGthDa026050@juw15.nfra.nl> <20041123174937.GL9148@tausq.org> <41AA09F8.4020006@gnu.org> <20041128184141.GG6359@tausq.org> <41AA2D08.3030304@gnu.org> <20041129033013.GJ6359@tausq.org> <41AB3C1D.80509@gnu.org> <20041201061924.GZ6359@tausq.org> <20041201171137.GA8037@nevyn.them.org> In-Reply-To: <20041201171137.GA8037@nevyn.them.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2004-12/txt/msg00031.txt.bz2 Daniel Jacobowitz wrote: > On Tue, Nov 30, 2004 at 10:19:24PM -0800, Randolph Chung wrote: > >>i experimented with another proposal which is to adjust the pc when we >>are at a nullified instruction. i modified target_read_pc () to return >>the previous (or next) pc when we are at a nullified instruction. this >>fixes some of the failures but causes new failures with the >>"recurse.exp" test. i need to investigate that some more. but teaching >>target_read_pc() to lie about the current pc seems to be suboptimal. >> >>lastly a comment about sparc -- i think the sparc case is simpler >>because it doesn't have conditional nullification. so looking at a >>particular insn you can always determine if the next insn will be >>nullified or not. this is not always the case for hppa. > > > Randolph, > > Here's an off-the-cuff idea for you. Could you actually skip the > nullified instruction, if you had a hook in the right place? That is, > when a thread stops, if it is stopped at a nullified instruction, > forcibly move it to the next instruction before returning control to > GDB. Read the discussion between Randolf and myself. This doesn't work for core files. > This is probably not feasible if you have to use single-stepping to end > up in the right place. If you can compute the right place and adjust > registers, though, it shouldn't be hard. Andrew