From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca (simark.ca [158.69.221.121]) by sourceware.org (Postfix) with ESMTPS id 4889C385843A for ; Fri, 3 Feb 2023 19:07:02 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 4889C385843A Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=simark.ca Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=simark.ca Received: from [172.16.0.192] (192-222-180-24.qc.cable.ebox.net [192.222.180.24]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id B19601E110; Fri, 3 Feb 2023 14:07:01 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=simark.ca; s=mail; t=1675451221; bh=M67UI5rZXIFs/9pp/laYdJmjMxHt52CYHXVDYf/+UB8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=koJEcUdAbND7psatY3Q6Ng0ehPhVO/R6hjUY2SYzC2MipTT3PiRF37lGXEpFi64Mc WOLicR9jBOAueP7Nyc4ewojyv1DeqHvyLyb/cOFXMRgIpUiN5/ef6JMJsjHcoKo1ru OgTwZwxW0GoCRfBYBrQVAjTTI8MAt42hG2XkCYiw= Message-ID: <8bf3989d-64b5-4de8-7ae4-e69280ec6313@simark.ca> Date: Fri, 3 Feb 2023 14:07:01 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH v3 7/8] gdb/aarch64: Detect vector length changes when debugging remotely Content-Language: fr To: Andrew Burgess , Thiago Jung Bauermann via Gdb-patches Cc: Thiago Jung Bauermann References: <20230130044518.3322695-1-thiago.bauermann@linaro.org> <20230130044518.3322695-8-thiago.bauermann@linaro.org> <878rhhtnis.fsf@redhat.com> <70edf893-10e4-f55d-dd2d-c57747e01def@simark.ca> <87pmaqr9fm.fsf@redhat.com> From: Simon Marchi In-Reply-To: <87pmaqr9fm.fsf@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-4.9 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,SPF_HELO_PASS,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 2/3/23 11:38, Andrew Burgess wrote: > Simon Marchi writes: > >>> I guess the point I'm driving towards is that maybe instead of a new >>> gdbarch method we should add something like gdbarch_from_tdesc into >>> arch-utils.c (like we have gdbarch_from_bfd and gdbarch_find_by_info), >>> which just does a lookup from tdesc. >> >> One thing I would like to add: I presume that this process >> (gdbarch_find_by_info) is somewhat expensive. Is there an easy way to >> short-circuit things earlier? Maybe if we detect that a thread has the >> same target desc id as before, we can avoid recomputing the gdbarch? >> Or, we can cache the gdbarch in the remote_target. > > Or could we cache the gdbarch in the tdesc itself? As you pointed out > for the previous patch, passing the same XML string will result in the > same tdesc object. So if we had gdbarch_from_tdesc, this can do the > expensive gdbarch lookup, then store the gdbarch in the tdesc object. > > Next time we call gdbarch_from_tdesc we can just check for a cached > gdbarch within the tdesc and return that... Yeah, maybe. The gdbarch points to the tdesc already, so this would add a link in the other direction. Simon