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 9A3F1C43334 for ; Fri, 17 Jun 2022 17:21:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383211AbiFQRVS (ORCPT ); Fri, 17 Jun 2022 13:21:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1383224AbiFQRVR (ORCPT ); Fri, 17 Jun 2022 13:21:17 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC9F8369D2 for ; Fri, 17 Jun 2022 10:21:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655486476; x=1687022476; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=THeq/t7OeFGS7kF1qxlxBPZVHuRcSkjtN1FGjFL0hbM=; b=Ye8dJHSBSDuLPoH7Lex6frifxt8Z07hT6WXqgjFylvNpz7npjjdGC1tJ /Ev5/L47z9BYaCLj4mOTD7kO6i5kpqw1j0LJIqkxqHdlq1W7THceJDWj2 EOb1KuQZGqQJJPXww4sRU+8LRllEt5eZtBtHSNrkEp7WX7cxRU91TSdF+ 1EZOpuWSEdmWNtt8GImxiDz4xVUFixRcOL2OfJxmcYMXs7NYeMnGJt95N d8+7VwCBgxPfGDxAnmY7kvPCi9oET/q0GNkYe19rhEAGR5loMqqIT9IEh MdLAm2yLA6PY5la6tZn1BrG3tZGccyM3s/CEGMjO77lPR+IGZJIIJIaYx Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10380"; a="277057060" X-IronPort-AV: E=Sophos;i="5.92,306,1650956400"; d="scan'208";a="277057060" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2022 07:40:55 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.92,306,1650956400"; d="scan'208";a="763274890" Received: from irvmail001.ir.intel.com ([10.43.11.63]) by orsmga005.jf.intel.com with ESMTP; 17 Jun 2022 07:40:49 -0700 Received: from newjersey.igk.intel.com (newjersey.igk.intel.com [10.102.20.203]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id 25HEeXl9024161; Fri, 17 Jun 2022 15:40:47 +0100 From: Alexander Lobakin To: Arnd Bergmann , Yury Norov Cc: Alexander Lobakin , Andy Shevchenko , Mark Rutland , Matt Turner , Brian Cain , Geert Uytterhoeven , Yoshinori Sato , Rich Felker , "David S. Miller" , Kees Cook , "Peter Zijlstra (Intel)" , Marco Elver , Borislav Petkov , Tony Luck , Maciej Fijalkowski , Jesse Brandeburg , Greg Kroah-Hartman , linux-alpha@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 7/7] lib: test_bitmap: add compile-time optimization/evaluations assertions Date: Fri, 17 Jun 2022 16:40:31 +0200 Message-Id: <20220617144031.2549432-8-alexandr.lobakin@intel.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220617144031.2549432-1-alexandr.lobakin@intel.com> References: <20220617144031.2549432-1-alexandr.lobakin@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org Add a function to the bitmap test suite, which will ensure that compilers are able to evaluate operations performed by the bitops/bitmap helpers to compile-time constants when all of the arguments are compile-time constants as well, or trigger a build bug otherwise. This should work on all architectures and all the optimization levels supported by Kbuild. The function doesn't perform any runtime tests and gets optimized out to nothing after passing the build assertions. Suggested-by: Yury Norov Signed-off-by: Alexander Lobakin --- lib/test_bitmap.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c index d5923a640457..3a7b09b82794 100644 --- a/lib/test_bitmap.c +++ b/lib/test_bitmap.c @@ -869,6 +869,50 @@ static void __init test_bitmap_print_buf(void) } } +static void __init test_bitmap_const_eval(void) +{ + DECLARE_BITMAP(bitmap, BITS_PER_LONG); + unsigned long initvar = BIT(2); + unsigned long bitopvar = 0; + unsigned long var = 0; + int res; + + /* + * Compilers must be able to optimize all of those to compile-time + * constants on any supported optimization level (-O2, -Os) and any + * architecture. Otherwise, trigger a build bug. + * The whole function gets optimized out then, there's nothing to do + * in runtime. + */ + + /* Equals to `unsigned long bitmap[1] = { BIT(5), }` */ + bitmap_clear(bitmap, 0, BITS_PER_LONG); + if (!test_bit(7, bitmap)) + bitmap_set(bitmap, 5, 1); + + /* Equals to `unsigned long bitopvar = BIT(20)` */ + __change_bit(31, &bitopvar); + bitmap_shift_right(&bitopvar, &bitopvar, 11, BITS_PER_LONG); + + /* Equals to `unsigned long var = BIT(25)` */ + var |= BIT(25); + if (var & BIT(0)) + var ^= GENMASK(9, 6); + + /* __const_hweight<32|64>(BIT(5)) == 1 */ + res = bitmap_weight(bitmap, 20); + BUILD_BUG_ON(!__builtin_constant_p(res)); + + /* !(BIT(31) & BIT(18)) == 1 */ + res = !test_bit(18, &bitopvar); + BUILD_BUG_ON(!__builtin_constant_p(res)); + + /* BIT(2) & GENMASK(14, 8) == 0 */ + BUILD_BUG_ON(!__builtin_constant_p(initvar & GENMASK(14, 8))); + /* ~BIT(25) */ + BUILD_BUG_ON(!__builtin_constant_p(~var)); +} + static void __init selftest(void) { test_zero_clear(); @@ -884,6 +928,7 @@ static void __init selftest(void) test_for_each_set_clump8(); test_bitmap_cut(); test_bitmap_print_buf(); + test_bitmap_const_eval(); } KSTM_MODULE_LOADERS(test_bitmap); -- 2.36.1