From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id GdfMDBUriGrPkTMAWB0awg (envelope-from ) for ; Fri, 21 Aug 2026 06:40:21 -0400 Authentication-Results: simark.ca; dkim=pass (2048-bit key; unprotected) header.d=embecosm.com header.i=@embecosm.com header.a=rsa-sha256 header.s=google header.b=e7dKLghk; dkim-atps=neutral Received: by simark.ca (Postfix, from userid 112) id 2D7CF1E033; Fri, 21 Aug 2026 06:40:21 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-25) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-5.4 required=5.0 tests=ARC_SIGNED,ARC_VALID,BAYES_00, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=unavailable autolearn_force=no version=4.0.1 Received: from vm01.sourceware.org (vm01.sourceware.org [38.145.34.32]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 3430B1E033 for ; Fri, 21 Aug 2026 06:40:20 -0400 (EDT) Received: from vm01.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 77CA64BB1C15 for ; Fri, 21 Aug 2026 10:40:19 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 77CA64BB1C15 Authentication-Results: sourceware.org; dkim=pass (2048-bit key, unprotected) header.d=embecosm.com header.i=@embecosm.com header.a=rsa-sha256 header.s=google header.b=e7dKLghk Received: from mail-wr1-x432.google.com (mail-wr1-x432.google.com [IPv6:2a00:1450:4864:20::432]) by sourceware.org (Postfix) with ESMTPS id 9260F4BA2E04 for ; Fri, 21 Aug 2026 10:39:54 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 9260F4BA2E04 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=embecosm.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=embecosm.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 9260F4BA2E04 Authentication-Results: sourceware.org; arc=none smtp.remote-ip=2a00:1450:4864:20::432 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1787308794; cv=none; b=nm1VcJOX8JFB7YcKxmbsc8BeCwlxBAgMUBYmqjEBVYSh+7qbZ6B9AuvBngHjiFnJRBZ0LOSSr0/JP9b1SKiPQ59f1/PLsncxChynTxwyCXiTJkfE63pBRpJmmHJISePB29A7lwYd0xQMcu09LjuFgWU+50/FO/NYGaIZETdWF04= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1787308794; c=relaxed/simple; bh=+BJ1KDQzKqU3rhAVIIs58/iva2pZlwk7C3YoXsQsSY8=; h=DKIM-Signature:Message-ID:Date:MIME-Version:Subject:To:From; b=j+oQ0Xj3S/WAZLEuaZnzOi8VNbe6Yx/mdpcZqluc1cc4GQF/nqdO1a6qFTiDmIuH/aDYo404XNPdDNTiG1u7/4K/CExzV5lWsDjL0JpdjsMi62MEvt5Wo+MMKf0TM4WemA4qwxVAVMyVDQ/VXbrTDnYSvxnlpZzt3GMfkhYEiHQ= ARC-Authentication-Results: i=1; sourceware.org; dkim=pass (2048-bit key, unprotected) header.d=embecosm.com header.i=@embecosm.com header.a=rsa-sha256 header.s=google header.b=e7dKLghk DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 9260F4BA2E04 Received: by mail-wr1-x432.google.com with SMTP id ffacd0b85a97d-480001972b8so254090f8f.2 for ; Fri, 21 Aug 2026 03:39:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=embecosm.com; s=google; t=1787308793; x=1787913593; darn=sourceware.org; h=content-transfer-encoding:content-type:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=J6wPZpaL27jJ/MpB7VCGMdAhGfuq2gDO/vWSHTtQebE=; b=e7dKLghkKLBqbdEqSBqjKVlofrjb3mtwLfA56Uz2qI03vpAOQXOKctAWCVdYjbeRVA SDe5/AwgseBOKJrT/r831zqdXmFm+Lq62Jfr/QbJU0f0dGmcuxXunrOPSKmtwdrzT9F6 a/9k6cOM8sPOIyMyLnxpD02D5SlgaPB4dnqbeR08YfsqGJ9UCGY9Y/HN6XENd4QfrMfU eepORUMOGafphDRkBmfYZgpvQZX/IId9bxWUnvgA5OyL7fSgk7aKnreBqaiwj0rX0GGx tq22uZ5Zwkn4FTMNrFjfvWZQCZ9e1WhqO7c54ZM4pDA+IxH/C76OHViOWDQzUcaLtG/7 Ukyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787308793; x=1787913593; h=content-transfer-encoding:content-type:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=J6wPZpaL27jJ/MpB7VCGMdAhGfuq2gDO/vWSHTtQebE=; b=LSaY060sVI8Ndg1j9o0gjrnLTTGnk0U2Yn+UQyO2+2jUs+xZYx/bBcuVX6GsxW3nlr BogYgnGFa77Kg9qPSRyVa/CIJXsVaeJStUND1lWfO1tXgiALvmvclAuZpGHieVDcl6YW 6uRYtZeo2ReuZWqFwN2Q1EwKOU/sZuEC1AbO2Ma9OQcAH+Y5VoqGRen791klGwi7P7NE niFn+4z+yLmKa5TIreuVy8SHcE6xqALIGesLRe4Rpmd/xYXC9MBMCipR8FqiWGMA8BVz dRulbUi3b0KY+U1ddWuQ4AxUI0dVE5aju1TS2erm1SAQwn/MMz2G5pEzaROKlRBKtDeV sYeA== X-Forwarded-Encrypted: i=1; AHgh+RpOiIsLeJ0HPJW5Zw6njoGZ+6GGLQaHfuL+b9cwdM+EiupTUVq5zq8IHkmsfJzsV3qZzfK+u15bLJClxQ==@sourceware.org X-Gm-Message-State: AFuF++lcALgnODsbhMEC8wyfA2Y1VqJN1edeJC3g/EIBYPNdMA0pErVM LsC5cWxskpTSNNWa21yJhIC9KlUN+/Xao/V0uhn/Z08Al9kTuDravpJuzUMiN0n3aYI= X-Gm-Gg: AR+sD11HC35SeSR1/ZMwP/QWOgwmIXakDrLU4UvHAryedLiO/eVPouvmLw1ajizj7oK E0YhWNULOiIu4homka+UfHHZAmEOsiWejmo3OMjfzGvfMIhg5jQEg1SiuCUhgOpMab1KLHDT6/4 Gj0ACwR0VpEn1keBsc+FEtnaeukTby+ENl3P/jxnS76l44sQJxvHFAmgDk5Xffgr37Fh+PyLDxq F5Pdn9Uf/8JMVuIu+x+P8nqYFfdXQWiKbCTSwA26JxrcGt+aKpCCGILEMBmrHonxqRrwmSPF8dU 5Ph9lqseqXhMZEJzMUziyvevNRYp+GpsEcMThb9kkZBrsiLZFu6jL4Gx/7/g73zLLVT23UGSf0c yQQhkPZdbGI7wHKvoR6PM4YHChDuoGgfIOLin709rhUJ+3M6PdyV7vAnjvLmbXiM9OE1z/G0uCh RG25G0yOGOMQdV2kUoY1wK/5/H4ERYoDU9IrWjVJzd4tM6NqhswqeXUFTwYiW2SzUNwSnmaPsXh Ii9xzbd1Rz9ZUPa4gORI6J+WHvTf0M7kJIn0pp3aJp+USxSCWoWCdSqKooYejLV X-Received: by 2002:a05:6000:238a:b0:47f:4919:d5b2 with SMTP id ffacd0b85a97d-482c0b4a293mr8081156f8f.1.1787308793541; Fri, 21 Aug 2026 03:39:53 -0700 (PDT) Received: from [192.168.0.55] (sals-04-b2-v4wan-167965-cust660.vm36.cable.virginm.net. [80.3.10.149]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-482b145c9d7sm18707894f8f.15.2026.08.21.03.39.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 Aug 2026 03:39:53 -0700 (PDT) Message-ID: Date: Fri, 21 Aug 2026 11:39:52 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 1/1] gdb: Add python support for transforming register unwind values To: Simon Marchi , gdb-patches@sourceware.org Cc: aburgess@redhat.com, eliz@gnu.org References: <20260520131607.32885-1-craig.blackmore@embecosm.com> <20260608120437.566738-1-craig.blackmore@embecosm.com> <20260608120437.566738-2-craig.blackmore@embecosm.com> <94197116-e5d5-4c96-9acc-76b72cf544c4@simark.ca> Content-Language: en-US From: Craig Blackmore Autocrypt: addr=craig.blackmore@embecosm.com; keydata= xsBNBFdIF8oBCACwrsvc6YVfzJRT+ZoBfL9jEb8ITwNahDxCGSG6sIWrJ9UFeTwE8fnNhMpz RyFRm0OXruS5k/8YHJHrxKxFY9cgZ3CWNftXEjRqURUWGtN/ESiw0J7nVfhSGQTo3LBzpXZ1 0JHk4ZHKDJKYa+fhybCHOs19BfP3HydHoTlc5QTKMfom0X/xo7WDdwUYeZsjD9u8IzHk7gNw 05Abk1vqni+J7Fghjp4RI8W3IsjpKOfV3f02OyO/MTSraXNyejO4JRl0A8b3q1Lq+G6Z7o5n LVief5JpkRyzWQSawTIBKmRZa9EzAKZXd6IJdY/sZt7pTir5EP7MHq4a+AtKfKuDkrDDABEB AAHNLkNyYWlnIEJsYWNrbW9yZSA8Y3JhaWcuYmxhY2ttb3JlQGVtYmVjb3NtLmNvbT7CwHgE EwECACIFAldIF8oCGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGEeRQLLl5WtydMH /1nYd9jmOBaF8w5gGgjF5eOO5b/cdUegmO///VYj/5R7iF/zbB6KgF0Obo5h2gG9AIfsZG+T ybuTx7oU1DZYEIndw+YP9c9Yi5de5UzEHwbJiV57W0n+MP0Widgw7p6XJmUQ1XbHxdcWp7nY EJa8ASKLuuIhO8JFUXbQ8BcUiWbsA/JxgCzeid8iixGrzPWj6iFzoK2mX4GqP+24pXSDUamM TXmSQd2taYEsyUdJNiEkUC51ncRcMuThjdtfn6Ok+7lHjh3Zz8q0keJz5pnIp4EXdkAgKSjq U42PMrd3v1HoIFINTtr5F23OdkxoQzysu4GMO4pkw5pwz95Uckr08ojOwE0EV0gXygEIAKv/ luYHmCG/qefgzdbnegwMdG5753NJ+zGxFltFX6aaOPZ8go9Omf6zwjybUKv6Qx6AlDanwCl3 ewVQs+h9iW8uaQBRgeDmwAGMG/doBiFqs7X0jBf23exMiJezXlKb2ZlKzMAbzJ87408AzRaV sZdwEpXHVi2mRPoXtMrqL5iQEyG5hdx2ySj5164DIgVOs/ypFiaiFaDPkIcAQTzJrxsbt6pf iI9kT93DO9nRKVV0pPWztV8P5gKM8HY2rS0wQcfrqAU6T89Aa0VFw92J+w5d2spF8MUNPsvR NLm9ooCF3YME9STYHXrNH1U9fJUWpIC+b49UoWSWRD9nwl2h2i8AEQEAAcLAXwQYAQIACQUC V0gXygIbDAAKCRBhHkUCy5eVreLbB/sHPs1xu78uNV8O4UPTX7D5zBBS3nsrbDr+8stmXRap xbvo6kqKzIMAXuO3bYB/NyJ/tFzuFr9Tjd/2g56D2186bp01/kgxJ9CEl/m2T3lG3DlxIoLg pCExzTLTb8zH/7/6mdeJ17cdnrK+2QAKYctReVPAC67cq5KmUyU3bv5e1JzhV4ezz/i/O+Jv el112ZEsa54ya9KZOUHbgAR6hLnRWIa+8yQTtXqYRc3LxLRfS80Wn0Err1YvqFYzJsQMC8ND xAeEuqQ1gfk1b0jmv7tYljNqsHqzGVbuWz6hyzyLv5GjcdSDKpbw/797gRKQSY8Gty5ynfUH O4kKyuZPrE8P In-Reply-To: <94197116-e5d5-4c96-9acc-76b72cf544c4@simark.ca> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 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 On 12/08/2026 15:43, Simon Marchi wrote: > On 6/8/26 8:04 AM, Craig Blackmore wrote: >> This patch addresses the scenario where a register value is saved in >> some mangled form on the target and gdb does not have sufficient >> information to demangle it. >> >> After getting a register value from an unwinder, gdb will call out to >> extension languages to allow the value to be transformed. This avoids >> having to write a new unwinder and allows the standard unwinders to be >> used. >> >> This patch adds the python class >> `gdb.unwinder.UnwindRegisterValueTransformer` which is the base class >> for transformers which provide a `read` method for transforming unwind >> register values that have been read. There is no similar support for >> transforming values being written back to the target as this was not >> something I needed to be able to do. Such support can be added to the >> python API in future by supporting a `write` method. Currently writing >> back to a transformed register will produce an "Attempt to assign to an >> unmodifiable value" error. >> >> Only one transformer can be registered globally at any one time. >> Attempting to register more than one transformer or to any other locus >> produces an error. The function for registering transformers takes a >> locus to allow other loci to be supported in future. Registered >> transformers are stored in a list so that registering multiple >> transformers may be supported in future. >> >> `gdbpy_get_register_descriptor` is now externally visible as it is used >> to create a gdb.RegisterDescriptor object to pass to the `read` method. >> >> This patch adds read-only attribute `gdb.Value.lval_type` which >> transformer methods can use to decide to skip modifying values that did >> not come directly from the target and may not need transforming, for >> example, values taken directly from DWARF. > I remember that when discussing DWARF locations on the stack things with > Pedro (upcoming DWARF 6 features), and how GDB would implement them, the > conclusion was that the lval_type enum was really conflating two things > that should be orthogonal. If I remember correctly, I think that it > should be two axis: > > - the location part: where are the bits located (register, memory, > nowhere) > - the lval-ness: is this a value that can be assigned > > The details are blurry because it's been a while, and unfortunately > Pedro is OOO at the moment. I'd like to have a chat with him about this > once he's back, before we expose this concept to Python. It might just > be a matter of choosing a future-proof name for the new property. From > what I understand, what you care about in the > UnwindRegisterValueTransformer implementation is the "location" aspect > of it, so perhaps the property name could convey just that, and not the > "lval" aspect. Hi Simon, Yes, it is only the location aspect that this implementation cares about. Thanks, Craig > Simon