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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 1453CC04AB1 for ; Thu, 9 May 2019 13:01:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E25902173C for ; Thu, 9 May 2019 13:01:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726714AbfEINBC (ORCPT ); Thu, 9 May 2019 09:01:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:51844 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726054AbfEINBC (ORCPT ); Thu, 9 May 2019 09:01:02 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 13E4520989; Thu, 9 May 2019 13:01:00 +0000 (UTC) Date: Thu, 9 May 2019 09:00:58 -0400 From: Steven Rostedt To: Linus Torvalds Cc: David Laight , Peter Zijlstra , "tglx@linutronix.de" , "hpa@zytor.com" , "julien.thierry@arm.com" , "will.deacon@arm.com" , "luto@amacapital.net" , "mingo@kernel.org" , "catalin.marinas@arm.com" , "james.morse@arm.com" , "valentin.schneider@arm.com" , "brgerst@gmail.com" , "jpoimboe@redhat.com" , "luto@kernel.org" , "bp@alien8.de" , "dvlasenk@redhat.com" , "linux-kernel@vger.kernel.org" , "dvyukov@google.com" Subject: Re: [PATCH 02/25] tracing: Improve "if" macro code generation Message-ID: <20190509090058.6554dc81@gandalf.local.home> In-Reply-To: References: <20190318153840.906404905@infradead.org> <20190318155140.058627431@infradead.org> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Mar 2019 10:26:17 -0700 Linus Torvalds wrote: > On Wed, Mar 20, 2019 at 4:17 AM David Laight wrote: > > > > > ______r = !!(cond); \ > > > > Is that (or maybe just the !!) needed any more?? > > It is, because the 'cond' expression might not be an int, it could be > a test for a pointer being non-NULL, or an u64 being non-zero, and not > having the "!!" would mean that you'd get a warning or drop bits when > assigning to 'int'. > > And you do need the new temporary variable to avoid double evaluation > the way that code is written. > > That said, I do think the code is really ugly. We could: > > - avoid the temporary by just simplifying things. > > - do the '!!' just once in the parent macro. > > - Steven has this crazy model of "more underscores are better". They > aren't. They don't help if things nest anyway, but what does help is > meaningful names. Both when things don't nest, and when looking at > generated asm files. > > - ,, and finally, what _is_ better is to chop things up so that they > are smaller and make each macro do only one thing > > So maybe do the patch something like the attached instead? Completely > untested, but it looks sane to me. > Linus, This patch works. Can I get your Signed-off-by for it? -- Steve