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=-21.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=unavailable 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 BC501C43381 for ; Tue, 19 Jan 2021 13:30:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9457920754 for ; Tue, 19 Jan 2021 13:30:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393119AbhASN2k (ORCPT ); Tue, 19 Jan 2021 08:28:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391951AbhASNSf (ORCPT ); Tue, 19 Jan 2021 08:18:35 -0500 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84CF8C061575 for ; Tue, 19 Jan 2021 05:17:33 -0800 (PST) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: aratiu) with ESMTPSA id D0B0C1F451BA From: Adrian Ratiu To: linux-arm-kernel@lists.infradead.org Cc: Nathan Chancellor , Nick Desaulniers , Arnd Bergmann , Russell King , Ard Biesheuvel , Arvind Sankar , clang-built-linux , kernel@collabora.com, Linux Kernel Mailing List Subject: [PATCH v4 1/2] arm: lib: xor-neon: remove unnecessary GCC < 4.6 warning Date: Tue, 19 Jan 2021 15:17:23 +0200 Message-Id: <20210119131724.308884-2-adrian.ratiu@collabora.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210119131724.308884-1-adrian.ratiu@collabora.com> References: <20210119131724.308884-1-adrian.ratiu@collabora.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nathan Chancellor Drop warning because kernel now requires GCC >= v4.9 after commit 6ec4476ac825 ("Raise gcc version requirement to 4.9") and clarify that -ftree-vectorize now always needs enabling for GCC by directly testing the presence of CONFIG_CC_IS_GCC. Another reason to remove the warning is that Clang exposes itself as GCC < 4.6 so it triggers the warning about GCC which doesn't make much sense and misleads Clang users by telling them to update GCC. Because Clang is now supported by the kernel print a clear Clang-specific warning. Link: https://github.com/ClangBuiltLinux/linux/issues/496 Link: https://github.com/ClangBuiltLinux/linux/issues/503 Reported-by: Nick Desaulniers Reviewed-by: Nick Desaulniers Signed-off-by: Nathan Chancellor Signed-off-by: Adrian Ratiu --- arch/arm/lib/xor-neon.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/arch/arm/lib/xor-neon.c b/arch/arm/lib/xor-neon.c index b99dd8e1c93f..f9f3601cc2d1 100644 --- a/arch/arm/lib/xor-neon.c +++ b/arch/arm/lib/xor-neon.c @@ -14,20 +14,22 @@ MODULE_LICENSE("GPL"); #error You should compile this file with '-march=armv7-a -mfloat-abi=softfp -mfpu=neon' #endif +/* + * TODO: Even though -ftree-vectorize is enabled by default in Clang, the + * compiler does not produce vectorized code due to its cost model. + * See: https://github.com/ClangBuiltLinux/linux/issues/503 + */ +#ifdef CONFIG_CC_IS_CLANG +#warning Clang does not vectorize code in this file. +#endif + /* * Pull in the reference implementations while instructing GCC (through * -ftree-vectorize) to attempt to exploit implicit parallelism and emit * NEON instructions. */ -#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6) +#ifdef CONFIG_CC_IS_GCC #pragma GCC optimize "tree-vectorize" -#else -/* - * While older versions of GCC do not generate incorrect code, they fail to - * recognize the parallel nature of these functions, and emit plain ARM code, - * which is known to be slower than the optimized ARM code in asm-arm/xor.h. - */ -#warning This code requires at least version 4.6 of GCC #endif #pragma GCC diagnostic ignored "-Wunused-variable" -- 2.30.0