From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3CAAC433E6 for ; Thu, 18 Feb 2021 11:54:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FF0164D79 for ; Thu, 18 Feb 2021 11:54:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229946AbhBRLxU (ORCPT ); Thu, 18 Feb 2021 06:53:20 -0500 Received: from mail3-relais-sop.national.inria.fr ([192.134.164.104]:29880 "EHLO mail3-relais-sop.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232715AbhBRKRs (ORCPT ); Thu, 18 Feb 2021 05:17:48 -0500 X-IronPort-AV: E=Sophos;i="5.81,186,1610406000"; d="scan'208";a="373421670" Received: from 173.121.68.85.rev.sfr.net (HELO hadrien) ([85.68.121.173]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Feb 2021 11:17:02 +0100 Date: Thu, 18 Feb 2021 11:17:02 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Denis Efremov cc: cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org Subject: Re: [PATCH] coccinelle: misc: add swap script In-Reply-To: Message-ID: References: <20210216080133.455456-1-efremov@linux.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 18 Feb 2021, Denis Efremov wrote: > > > On 2/18/21 12:31 AM, Julia Lawall wrote: > >> +@depends on patch@ > >> +identifier tmp; > >> +expression a, b; > >> +type T; > >> +@@ > >> + > >> +( > >> +- T tmp; > >> +| > >> +- T tmp = 0; > >> +| > >> +- T *tmp = NULL; > >> +) > >> +... when != tmp > >> +- tmp = a; > >> +- a = b; > >> +- b = tmp; > >> ++ swap(a, b); > >> +... when != tmp > > > > In this rule and the next one, if you remove the final ; from the b = tmp > > line and from the swap line, and put it into context code afterwards, them > > the generated code looks better on cases like fs/xfs/xfs_inode.c in the > > function xfs_lock_two_inodes where two successive swap calls are > > generated. > > > > There are also some cases such as drivers/net/wireless/ath/ath5k/phy.c in > > the function ath5k_hw_get_median_noise_floor where the swap code makes up > > a whole if branch. > > > In this cases it would be good to remove the {}. > > How this can be handled? > > If I use this pattern: > @depends on patch@ > identifier tmp; > expression a, b; > @@ > > ( > if (...) > - { > - tmp = a; > - a = b; > - b = tmp > + swap(a, b) > ; > - } > | > - tmp = a; > - a = b; > - b = tmp > + swap(a, b) > ; > ) > > The tool fails with error: > > EXN: Failure("rule starting on line 58: already tagged token:\nC code > context\nFile \"drivers/net/wireless/ath/ath5k/phy.c\", line 1574, > column 4, charpos = 41650\n around = 'sort',\n whole content = > \t\t\t\tsort[j - 1] = tmp;") in drivers/net/wireless/ath/ath5k/phy.c A disjunction basically says "at this node in the cfg, can I match the first patter, or can I match the second pattern, etc." Unfortunately in this case the two branches start matching at different nodes, so the short circuit aspect of a disjunction isn't used, and it matches both patterns. The solution is to just make two rules. The first for the if case and the second for everything else. julia