From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from wout3-smtp.messagingengine.com (wout3-smtp.messagingengine.com [64.147.123.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D04AE4597D for ; Sun, 28 Jan 2024 22:34:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=64.147.123.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706481300; cv=none; b=qGpSg25nrBEoqyIbzU/Dmr5JLDfnJUir8JVV8Qv0EnmiyMzBx5J6avXgAhwIKU7dIyEUIzp/jAd2LWIR2vZlVpXeE1peMrM+Weh3f8qQ9ms+S39x5cJbaX6LpoPINpkRNYTdM7+OiFymeW0SBlQ7clfC2UhaoyqtxhQz5s3l/OM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706481300; c=relaxed/simple; bh=0cFPyEkMwRW7LWGPRa3CjFrN1T2de+1DrXN5dT6WK3E=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=U1OBaFDodjAAXCfKiLALwI2SyjiagN77yj0VzCnv8Zo+bDfM7U+IYJlXz73uJ4Q++rNRNdQE0mEckl6wyOZ4PU7c8M1kfM3tQu2lLxkFKWhvHxNdt4JtkhxxkMlM5zgZG1msxQ7P4g7oGjUiETbk0Kf68LuWFhq3Z2l7Mi9/0A0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org; spf=none smtp.mailfrom=linux-m68k.org; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=DY5XBcTs; arc=none smtp.client-ip=64.147.123.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux-m68k.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="DY5XBcTs" Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id 2C4B43200AAC; Sun, 28 Jan 2024 17:34:56 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Sun, 28 Jan 2024 17:34:57 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; t=1706481295; x=1706567695; bh=g12uW+xPEP7nxRNTu1rV1k935e2o J9MX42MHVhfS0zU=; b=DY5XBcTs45FuuMOCLbeAiSEulwUpTzVa8g2swmJYmfOR 2uQqyfCJfbxs3mc6Cu97ndZje54fB9WBQil0AX8Z7826wPQhVnBBqEOUaIStAkqG N1GL41pPh7akrTey7WvhRS9yA33u6O45dUxEa822U7tzgZStP4rWoo62T2pSW8pS WUnFRv/ZZHoaRluGgcNZdHGWTF3XwuSZhnGttz/ltWVdVBbt9Yj6hPuB6PrlL78t tZH3I0r/AFTF1omfr84Wly/F0bIUoVldciL9wwWTfuDXqa97Bt/iNl5Pqd6JgQf5 N4B5+9X4GkzBkf/Yj37jj2YIQDsMbnIAMziFCHvYMw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvkedrfedtvddgudeiudcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpeffhffvvefujgfkfhggtgesthdtredttddtvdenucfhrhhomhephfhinhhn ucfvhhgrihhnuceofhhthhgrihhnsehlihhnuhigqdhmieekkhdrohhrgheqnecuggftrf grthhtvghrnhepleeuheelheekgfeuvedtveetjeekhfffkeeffffftdfgjeevkeegfedv ueehueelnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomh epfhhthhgrihhnsehlihhnuhigqdhmieekkhdrohhrgh X-ME-Proxy: Feedback-ID: i58a146ae:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 28 Jan 2024 17:34:50 -0500 (EST) Date: Mon, 29 Jan 2024 09:34:56 +1100 (AEDT) From: Finn Thain To: Vincent MAILHOL cc: David Laight , Andrew Morton , "linux-kernel@vger.kernel.org" , Yury Norov , Nick Desaulniers , Douglas Anderson , Kees Cook , Petr Mladek , Randy Dunlap , Zhaoyang Huang , Geert Uytterhoeven , Marco Elver , Brian Cain , Geert Uytterhoeven , Matthew Wilcox , "Paul E . McKenney" , "linux-m68k@lists.linux-m68k.org" Subject: Re: [PATCH v4 2/5] m68k/bitops: use __builtin_{clz,ctzl,ffs} to evaluate constant expressions In-Reply-To: Message-ID: <77831c6f-7fc9-c42d-b29b-c3b2f3f5e687@linux-m68k.org> References: <20221111081316.30373-1-mailhol.vincent@wanadoo.fr> <20240128050449.1332798-1-mailhol.vincent@wanadoo.fr> <20240128050449.1332798-3-mailhol.vincent@wanadoo.fr> <9d9be9dbe92f43d2a95d11d6b2f434c1@AcuMS.aculab.com> Precedence: bulk X-Mailing-List: linux-m68k@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Sun, 28 Jan 2024, Vincent MAILHOL wrote: > > > The asm is meant to produce better results when the argument is not > > > a constant expression. Is that because gcc's implementation has to satisfy requirements that are excessively stringent for the kernel's purposes? Or is it a compiler deficiency only affecting certain architectures? > ... The only thing I am not ready to do is to compare the produced > assembly code and confirm whether or not it is better to remove asm > code. > If you do the comparison and find no change, you get to say so in the commit log, and everyone is happy.