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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF8FAC43334 for ; Fri, 24 Jun 2022 14:29:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232351AbiFXO3D convert rfc822-to-8bit (ORCPT ); Fri, 24 Jun 2022 10:29:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230073AbiFXO3C (ORCPT ); Fri, 24 Jun 2022 10:29:02 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 1F57D54BF8 for ; Fri, 24 Jun 2022 07:29:00 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-118-bG_zLhqYP3-nJdlCra2C_g-1; Fri, 24 Jun 2022 15:28:57 +0100 X-MC-Unique: bG_zLhqYP3-nJdlCra2C_g-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.36; Fri, 24 Jun 2022 15:28:55 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.036; Fri, 24 Jun 2022 15:28:55 +0100 From: David Laight To: 'Joe Perches' , Aidan MacDonald CC: Mark Brown , Andy Shevchenko , Greg Kroah-Hartman , "Rafael J. Wysocki" , Matti Vaittinen , Linux Kernel Mailing List Subject: RE: [PATCH v2 01/12] regmap-irq: Convert bool bitfields to unsigned int Thread-Topic: [PATCH v2 01/12] regmap-irq: Convert bool bitfields to unsigned int Thread-Index: AQHYh9CnysjgLv0l70Wg+yJVLCyDEK1enHCA Date: Fri, 24 Jun 2022 14:28:55 +0000 Message-ID: References: <20220623211420.918875-1-aidanmacdonald.0x0@gmail.com> <20220623211420.918875-2-aidanmacdonald.0x0@gmail.com> <4937c0cc9dbc9d06cb626465bd37cbcf76c80a0b.camel@perches.com> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joe Perches > Sent: 24 June 2022 14:45 ... > I'm trying to show that conversions of bool:1->unsigned int:1 > as being trivial are not so trivial after all. > > It's fairly common to have code like: > > [bool] foo.bar = some_value & SETTING; > > where some value is tested for a mask/bit and a non-zero is true. > > So conversions of foo.bar from bool:1 to unsigned int:1 are not > wise unless all possible side effects are known. I can never decide whether: bool_c = bool_a & bool_b; can be compiled to a simple 'and' instruction, or requires a load of instructions in case bool_a and/or bool_b has a non-zero value without the bottom bit set. All other C types are cpu register types - so you know what happens. IMHO bool is an abomination and should not be used :-) David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)