From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dedi548.your-server.de (dedi548.your-server.de [85.10.215.148]) by sourceware.org (Postfix) with ESMTPS id BBB0F383C7E6 for ; Fri, 16 Dec 2022 10:39:56 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org BBB0F383C7E6 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=embedded-brains.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=embedded-brains.de Received: from sslproxy01.your-server.de ([78.46.139.224]) by dedi548.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1p688B-000HZY-8O; Fri, 16 Dec 2022 11:39:55 +0100 Received: from [82.100.198.138] (helo=mail.embedded-brains.de) by sslproxy01.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1p688B-0000tt-4R; Fri, 16 Dec 2022 11:39:55 +0100 Received: from localhost (localhost [127.0.0.1]) by mail.embedded-brains.de (Postfix) with ESMTP id C7A3D480181; Fri, 16 Dec 2022 11:39:54 +0100 (CET) Received: from mail.embedded-brains.de ([127.0.0.1]) by localhost (zimbra.eb.localhost [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id V_l1Gnvb_7Qy; Fri, 16 Dec 2022 11:39:54 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by mail.embedded-brains.de (Postfix) with ESMTP id 8532B480196; Fri, 16 Dec 2022 11:39:54 +0100 (CET) X-Virus-Scanned: amavisd-new at zimbra.eb.localhost Received: from mail.embedded-brains.de ([127.0.0.1]) by localhost (zimbra.eb.localhost [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id QdvGSNEgbfCK; Fri, 16 Dec 2022 11:39:54 +0100 (CET) Received: from [192.168.96.159] (unknown [192.168.96.159]) by mail.embedded-brains.de (Postfix) with ESMTPSA id 69FD6480181; Fri, 16 Dec 2022 11:39:54 +0100 (CET) Message-ID: Date: Fri, 16 Dec 2022 11:39:54 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH] gcov: Fix -fprofile-update=atomic To: Richard Biener Cc: gcc-patches@gcc.gnu.org References: <20221209135609.55159-1-sebastian.huber@embedded-brains.de> <2d6f0cf1-f979-b3a6-6daa-81fc0882a1d7@embedded-brains.de> Content-Language: en-US From: Sebastian Huber In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Authenticated-Sender: smtp-embedded@poldinet.de X-Virus-Scanned: Clear (ClamAV 0.103.7/26752/Fri Dec 16 09:25:27 2022) X-Spam-Status: No, score=-5.2 required=5.0 tests=BAYES_00,KAM_DMARC_STATUS,KAM_SHORT,NICE_REPLY_A,SPF_HELO_NONE,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 16.12.22 10:47, Richard Biener wrote: >> No, if you select -fprofile-update=3Datomic, then the updates shall be >> atomic from my point of view. If a fallback is acceptable, then you ca= n >> use -fprofile-update=3Dprefer-atomic. Using the fallback in >> -fprofile-update=3Datomic is a bug which prevents the use of gcov for >> multi-threaded applications on the lower end targets which do not have >> atomic operations in hardware. > Ah, OK. So the fallback there is libatomic calls as well then? Note > not all targets support libatomic, for those the failure mode is likely > a link error (which might be fine, but we eventually might want to > amend documentation to indicate this failure mode). It seems these library calls caused issues in the past: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D77466 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D77378 One option could be to emit calls to a new libgcov function: __gcov_inc_counter(counter) -> updated value This function could use a __gthread_mutex_t mutex for updates. This ends=20 up probably with quite a bad performance. --=20 embedded brains GmbH Herr Sebastian HUBER Dornierstr. 4 82178 Puchheim Germany email: sebastian.huber@embedded-brains.de phone: +49-89-18 94 741 - 16 fax: +49-89-18 94 741 - 08 Registergericht: Amtsgericht M=C3=BCnchen Registernummer: HRB 157899 Vertretungsberechtigte Gesch=C3=A4ftsf=C3=BChrer: Peter Rasmussen, Thomas= D=C3=B6rfler Unsere Datenschutzerkl=C3=A4rung finden Sie hier: https://embedded-brains.de/datenschutzerklaerung/