From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id uH5UFfyHvmCOSgAAWB0awg (envelope-from ) for ; Mon, 07 Jun 2021 16:56:28 -0400 Received: by simark.ca (Postfix, from userid 112) id 5543F1F163; Mon, 7 Jun 2021 16:56:28 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIM_SIGNED, MAILING_LIST_MULTI,T_DKIM_INVALID,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [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 760381E939 for ; Mon, 7 Jun 2021 16:56:27 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 11714393A419 for ; Mon, 7 Jun 2021 20:56:27 +0000 (GMT) Received: from gateway23.websitewelcome.com (gateway23.websitewelcome.com [192.185.48.104]) by sourceware.org (Postfix) with ESMTPS id 4BC5D3899078 for ; Mon, 7 Jun 2021 20:39:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4BC5D3899078 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=tromey.com Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=tromey.com Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway23.websitewelcome.com (Postfix) with ESMTP id 6831518A00 for ; Mon, 7 Jun 2021 15:39:00 -0500 (CDT) Received: from box5379.bluehost.com ([162.241.216.53]) by cmsmtp with SMTP id qM1UlsC1RMGeEqM1Ulj3W6; Mon, 07 Jun 2021 15:39:00 -0500 X-Authority-Reason: nr=8 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=fWNAqJViechLLN6xQLPfYxeN2bbRWx5fKYNyD3VabRo=; b=HUJDOHDpELzCxBsy2RgMb4w9Sn cG1Hl8ihAj6HdMtgpidS5LOg3U7zN8PtZb3kT/qe4zVz3ae4vM0WuZOsJKcFvVmEu9BaKKvpAV8+J jHmL5IY7dlEmIwUX8FR+SCcBu; Received: from 97-122-81-113.hlrn.qwest.net ([97.122.81.113]:52438 helo=murgatroyd) by box5379.bluehost.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1lqM1U-0048yq-0X; Mon, 07 Jun 2021 14:39:00 -0600 From: Tom Tromey To: Andrew Burgess Subject: Re: [PATCH 1/5] gdb/python: handle saving user registers in a frame unwinder References: <877dj5n2y7.fsf@tromey.com> <20210607161030.GU2672@embecosm.com> X-Attribution: Tom Date: Mon, 07 Jun 2021 14:38:59 -0600 In-Reply-To: <20210607161030.GU2672@embecosm.com> (Andrew Burgess's message of "Mon, 7 Jun 2021 17:10:30 +0100") Message-ID: <87o8chl89o.fsf@tromey.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (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: 97.122.81.113 X-Source-L: No X-Exim-ID: 1lqM1U-0048yq-0X X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: 97-122-81-113.hlrn.qwest.net (murgatroyd) [97.122.81.113]:52438 X-Source-Auth: tom+tromey.com X-Email-Count: 2 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: , Cc: Tom Tromey , gdb-patches@sourceware.org Errors-To: gdb-patches-bounces+public-inbox=simark.ca@sourceware.org Sender: "Gdb-patches" >> I was worried that requesting this would require unwinding the register, >> which is what is currently being done. But I suppose the idea is that >> the value is normally lazy, so it isn't actually unwound? Andrew> You are correct, accessing any register from an unwinder is going to Andrew> give us a lazy register value, which we'd expect (in this case) to Andrew> have the real register number for $pc, and the frame-id of the next Andrew> frame. Andrew> When you open with "I was worried that requesting this would require Andrew> unwinding the register...", was our concern just that this unwinding Andrew> might be expensive? Or are you worried that trying to do that might Andrew> break in some way? I was concerned that it would break in some way, by trying to unwind a register while in the process of unwinding. If it works, and is reasonably robust, then I'm fine. Andrew> I guess what I'm saying is, that yes it will be lazy, but I hadn't Andrew> really considered that an important part of the system. I think I see. Thanks. Tom