From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 48988 invoked by alias); 15 Feb 2016 10:57:58 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 48970 invoked by uid 89); 15 Feb 2016 10:57:56 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=similarly, mapping, our, ultimate X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Mon, 15 Feb 2016 10:57:55 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id B94B814CAB0; Mon, 15 Feb 2016 10:57:54 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u1FAvqlf010620; Mon, 15 Feb 2016 05:57:52 -0500 Message-ID: <56C1AF30.9010603@redhat.com> Date: Mon, 15 Feb 2016 10:57:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Yao Qi , =?UTF-8?B?TWFyY2luIEtvxZtjaWVsbmlja2k=?= CC: Antoine Tremblay , gdb-patches@sourceware.org, Gary Benson Subject: Re: [PATCH 3/4] Enable tracing of pseudo-registers on ARM References: <1452188697-23870-1-git-send-email-antoine.tremblay@ericsson.com> <1452188697-23870-4-git-send-email-antoine.tremblay@ericsson.com> <86egcineq0.fsf@gmail.com> <56BE002F.7050305@0x04.net> <86egcee0a6.fsf@gmail.com> In-Reply-To: <86egcee0a6.fsf@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-SW-Source: 2016-02/txt/msg00458.txt.bz2 On 02/15/2016 10:27 AM, Yao Qi wrote: > Marcin Kościelnicki writes: > >> >> Matter of fact, our support for >64-bit quantities in tracepoints is >> very poor at the moment - they can only be collected wholesale when >> they're single registers or contig memory areas. Use in expressions >> is out (if you happen to have something interesting in low 32 bits of >> a vector reg, sorry). Likewise, stiching them together with >> DW_op_piece (or whatever that was called) also fails (see >> https://sourceware.org/bugzilla/show_bug.cgi?id=17015). We could >> definitely use some improvement there... > > Yeah, agreed. > I think the that ultimate long term solution would pass actual DWARF expressions to the target side as collect actions. AX predates DWARF; probably if we were starting now we'd base it on DWARF. Then for the most part, we'd stop getting into trouble with mapping DWARF constructs to AX. I imagine we'd reuse gdb/dwarf2expr.c somehow, similarly to get-next-pcs, and that we'd maybe lower/rewrite some of the the DWARF before passing it to the target, to e.g., maybe avoid relying on debug info types or the frame/unwind machinery. +Gary, since given Infinity is based on DWARF expressions, it may be Gary's already looked at factoring out gdb/dwarf2expr.c. Not a trivial project though... Thanks, Pedro Alves