From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id 9FctOGTgfWSrlR4AWB0awg (envelope-from ) for ; Mon, 05 Jun 2023 09:17:24 -0400 Received: by simark.ca (Postfix, from userid 112) id D3A841E11E; Mon, 5 Jun 2023 09:17:24 -0400 (EDT) Authentication-Results: simark.ca; dkim=fail reason="signature verification failed" (768-bit key; unprotected) header.d=tromey.com header.i=@tromey.com header.a=rsa-sha256 header.s=default header.b=kL5oec0O; dkim-atps=neutral X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RDNS_NONE, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 Received: from sourceware.org (unknown [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 09D7F1E111 for ; Mon, 5 Jun 2023 09:17:23 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 5CD2F38323CC for ; Mon, 5 Jun 2023 13:17:22 +0000 (GMT) Received: from gproxy2-pub.mail.unifiedlayer.com (gproxy2-pub.mail.unifiedlayer.com [69.89.18.3]) by sourceware.org (Postfix) with ESMTPS id 5CE553850438 for ; Mon, 5 Jun 2023 13:17:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 5CE553850438 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=tromey.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tromey.com Received: from cmgw15.mail.unifiedlayer.com (unknown [10.0.90.130]) by progateway4.mail.pro1.eigbox.com (Postfix) with ESMTP id 7C647100443B0 for ; Mon, 5 Jun 2023 13:17:09 +0000 (UTC) Received: from box5379.bluehost.com ([162.241.216.53]) by cmsmtp with ESMTP id 6A57qSIDglGUM6A57qZmdB; Mon, 05 Jun 2023 13:17:09 +0000 X-Authority-Reason: nr=8 X-Authority-Analysis: v=2.4 cv=LqxXdlRc c=1 sm=1 tr=0 ts=647de055 a=ApxJNpeYhEAb1aAlGBBbmA==:117 a=ApxJNpeYhEAb1aAlGBBbmA==:17 a=dLZJa+xiwSxG16/P+YVxDGlgEgI=:19 a=of4jigFt-DYA:10:nop_rcvd_month_year a=Qbun_eYptAEA:10:endurance_base64_authed_username_1 a=CCpqsmhAAAAA:8 a=4ZlvB15mGyvDx3WZ2ooA:9 a=ul9cdbp4aOFLsgKbc677:22 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=tromey.com; s=default; h=Content-Type:MIME-Version:Message-ID:In-Reply-To:Date:References :Subject:Cc:To:From:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=mO2jmADWZje48j7mx/Vzf/Jwm/iJMlwVW/wb1XH+Zkg=; b=kL5oec0O4N2kdEku2D/BaMqDww ZyAsb/gc/k77pQGP59ntk6LBndV5vDBrBWSvHX+M+Gx8/PZZ678v997s9stHLfrt/YAd6l0Q2a2Zx FvZEViMDjeaO0Dkt/UKKvNEIc; Received: from 71-211-130-244.hlrn.qwest.net ([71.211.130.244]:49646 helo=murgatroyd) by box5379.bluehost.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1q6A57-002IUx-1a; Mon, 05 Jun 2023 07:17:09 -0600 From: Tom Tromey To: Kevin Buettner via Gdb-patches Cc: Kevin Buettner Subject: Re: [PATCH] Permit DW_OP_GNU_uninit to be used with DW_OP_piece References: <20230603183158.70474-1-kevinb@redhat.com> X-Attribution: Tom Date: Mon, 05 Jun 2023 07:17:08 -0600 In-Reply-To: <20230603183158.70474-1-kevinb@redhat.com> (Kevin Buettner via Gdb-patches's message of "Sat, 3 Jun 2023 11:31:58 -0700") Message-ID: <877csit5ez.fsf@tromey.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - box5379.bluehost.com X-AntiAbuse: Original Domain - sourceware.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - tromey.com X-BWhitelist: no X-Source-IP: 71.211.130.244 X-Source-L: No X-Exim-ID: 1q6A57-002IUx-1a X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: 71-211-130-244.hlrn.qwest.net (murgatroyd) [71.211.130.244]:49646 X-Source-Auth: tom+tromey.com X-Email-Count: 1 X-Source-Cap: ZWx5bnJvYmk7ZWx5bnJvYmk7Ym94NTM3OS5ibHVlaG9zdC5jb20= X-Local-Domain: yes X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces+public-inbox=simark.ca@sourceware.org Sender: "Gdb-patches" >>>>> "Kevin" == Kevin Buettner via Gdb-patches writes: Kevin> The test case in that bug report involved running gdb against the 'jq' Kevin> program (which is a command-line JSON processor) on Fedora 37. Since Kevin> the debug info is compiler (and compile-time option) dependent, it Kevin> won't necessarily show up in other distributions or even past or Kevin> future versions of Fedora. (E.g. when trying the example shown below Kevin> on Fedora 38, GDB says that the value of 'value' has been optimized Kevin> out. I.e. it does not demonstrate the same DWARF error that can be Kevin> see when using Fedora 37.) Ages ago, during one of the rewrites of the DWARF expression evaluator, I found out that DW_OP_GNU_uninit was not really documented. So, I just made it continue to work the way it had been described in the gdb sources. My recollection is that it required a special compiler argument to even get gcc to emit it. It's still undocumented as far as I can tell. So I'd suggest perhaps you could get someone to remove it from GCC, or from the jq build. It's barely used and IMO not really useful. That said, it's fine by me if you want to keep it around. Kevin> case DW_OP_GNU_uninit: Kevin> - if (op_ptr != op_end) Kevin> + if (op_ptr != op_end && *op_ptr != DW_OP_piece) Kevin> error (_("DWARF-2 expression error: DW_OP_GNU_uninit must always " Kevin> "be the very last op.")); If DW_OP_GNU_uninit can end a piece then the error message here should be updated. Also did you look at the other spots that understand DWARF expressions? There are 3 or 4 in gdb. Aside from this the patch is OK. Tom