From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Helmut Eller Newsgroups: gmane.emacs.devel Subject: Re: MPS prstack Date: Mon, 27 May 2024 16:54:52 +0200 Message-ID: <87ikyzl2yr.fsf@gmail.com> References: <87o790qsgm.fsf@gmail.com> <874jap95hi.fsf@gmail.com> <874janpa4m.fsf@gmail.com> <87le3vogt8.fsf@gmail.com> <87a5kbobt4.fsf@gmail.com> <86sey3v5p8.fsf@gnu.org> <87ed9nmnsm.fsf@gmail.com> <86ed9nv1nw.fsf@gnu.org> <87zfsbl4s9.fsf@gmail.com> <8E2D3922-AD21-4638-BFAA-FC4DF49284D6@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="29782"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Eli Zaretskii , gerd.moellmann@gmail.com, emacs-devel@gnu.org To: Mattias =?utf-8?Q?Engdeg=C3=A5rd?= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon May 27 16:55:51 2024 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1sBblP-0007Z0-30 for ged-emacs-devel@m.gmane-mx.org; Mon, 27 May 2024 16:55:51 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sBbkd-000691-Oh; Mon, 27 May 2024 10:55:03 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBbkY-00062p-Qx for emacs-devel@gnu.org; Mon, 27 May 2024 10:54:59 -0400 Original-Received: from mail-wr1-x431.google.com ([2a00:1450:4864:20::431]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1sBbkW-0004bS-Be; Mon, 27 May 2024 10:54:57 -0400 Original-Received: by mail-wr1-x431.google.com with SMTP id ffacd0b85a97d-356c4e926a3so2004641f8f.1; Mon, 27 May 2024 07:54:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1716821694; x=1717426494; darn=gnu.org; h=content-transfer-encoding:mime-version:user-agent:message-id:date :references:in-reply-to:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=EaZNL5l9BheF5gKSGdPLYkCNxDXnqKSV76lISJczbd4=; b=BedPI1Rm2ilsRuzMXOP5YQ96k3l4iUlkqbrrqjceJrL3QnZeZCUes8ig7s1/1YQ6z+ DU8wZ9mjfrUawHD1WhuIdDFYSNIXS/COuCVW/9ILEKydxxJ9po22HL0QlswYX1Co/5UG nRPrWosre2z+ufwyZ2ppiJAP2GPN1/QtcLhDMXjYicVHHvXXAQM2VhKyagCII3eH0MA4 1nPUC22GQNM9+P7fz3V7cWcHWNgS/HgCvgNnhi5DdRo6y6h4HbWvmwXVx7RmilW9IyBt JVuC44KEtjYxnBfS8MFIN7w/sBydeZM06BhJcK841D3el5iiHCQ9Pw7OE55FoYG5w1gk sTng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716821694; x=1717426494; h=content-transfer-encoding:mime-version:user-agent:message-id:date :references:in-reply-to:subject:cc:to:from:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=EaZNL5l9BheF5gKSGdPLYkCNxDXnqKSV76lISJczbd4=; b=krHpKihDEV9yrt6xs7oLdu0u8cv4BcLSGW4pJkwmoJcSFLJzKfKtvD2wiRzSc+hzu7 g4Yz426VAFYL5ZtHTyMJ5AXxfNuuslGLniPRoGiuHJSjaIuWJwcAUHZjDaYaaQzDPhxb VWmD+Ud8AqkmVUoFYDrfRJc9OKNyI5ogdCJP5o1T0J/2TC52p2gab9rg5whGzSwMYIqJ H6j3L05/CWhCq7Ro8tWqRBa230NdxriybH4Q0jacfV0fc6xBs2h3LXh9mGh9Ne4338mM sfUQr3wJULLBRvu1EmdCHVuJxuhcm4nduDGOtGXD05ghQksoPS5U6FyZil2M2H/TIdD6 yuTg== X-Forwarded-Encrypted: i=1; AJvYcCUFkrLlqTEPFiVgmwG0WfceAtB/CfTcFf0oorShxM9nt8upENqq/ycf7ZKLZurNYOo1RnDwNHGaRVvNUpCIXGfpE94J X-Gm-Message-State: AOJu0YzDaCjLbSHtAiA6a9MQDR+oJTXIjMHsx7RLrx5wArRIGiXpFS8W FdBTh2HarqHPQ6OX5lhUIvGXhJ7UOvoR0d8xv77ljChkoKyTte/YmDMmgA== X-Google-Smtp-Source: AGHT+IEDqYYk2gOISPbE7RE0HSWGdldQpd86JxLk3SEjS7LG4yz9M4nhjvT3sCQ0g9Y/OB781AccZQ== X-Received: by 2002:a5d:560f:0:b0:351:d2e6:9296 with SMTP id ffacd0b85a97d-355270588aamr6864461f8f.41.1716821693936; Mon, 27 May 2024 07:54:53 -0700 (PDT) Original-Received: from caladan (dial-188233.pool.broadband44.net. [212.46.188.233]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3577505a218sm6081612f8f.31.2024.05.27.07.54.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 May 2024 07:54:53 -0700 (PDT) In-Reply-To: <8E2D3922-AD21-4638-BFAA-FC4DF49284D6@gmail.com> ("Mattias =?utf-8?Q?Engdeg=C3=A5rd=22's?= message of "Mon, 27 May 2024 16:37:56 +0200") Received-SPF: pass client-ip=2a00:1450:4864:20::431; envelope-from=eller.helmut@gmail.com; helo=mail-wr1-x431.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:319613 Archived-At: On Mon, May 27 2024, Mattias Engdeg=C3=A5rd wrote: > 27 maj 2024 kl. 16.15 skrev Helmut Eller : > >> prstack.stack[prstack.sp] =3D e; >> __atomic_store_n (&prstack.sp, prstack.sp + 1, __ATOMIC_SEQ_CST); > > Surely that is a severe overkill when all we need is a compiler barrier? > Or have I misunderstood the context the scanners are called in? > Shouldn't they have the same view of memory as the mutator? The __atomic_store_n mainly prevents the compiler from reordering instructions. The generated code uses xchg in one version and mov in the other. I doubt that it makes any difference to the hardware, but using __atomic_store_n documents a subtle point.