From patchwork Thu Sep 16 18:40:17 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nathan Chancellor X-Patchwork-Id: 12499981 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 DAA12C433F5 for ; Thu, 16 Sep 2021 18:42:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B75F06103B for ; Thu, 16 Sep 2021 18:42:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349225AbhIPSnn (ORCPT ); Thu, 16 Sep 2021 14:43:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:44738 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348867AbhIPSn2 (ORCPT ); Thu, 16 Sep 2021 14:43:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B876E6103B; Thu, 16 Sep 2021 18:42:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631817727; bh=+Ka55t+zK8hXcliKTLebgVmF2QEIa1Ci4abGrfu4t7g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sreg9WjosXGGTgtw/e840hKZkI6/W2sz0RJKHKlfvPnOJvMs/BsHNbUVRCGSlFidD o0ACjDq37MUmY6jPhs887PQMPfCmtX4uYm3czgPgBJgdANzspfC9ITaM35/HIkVfa1 CjC3njZqtRskHPI539xD+hTuBhkniyAkeFiNFni0LR7DEMYIsOHidJHpwCF9MJY/ex AQ6yP/7u1VKzRrW2GHf0xiLnhYqHGjcUcFc/zMRh+3iDFSHSXt4xFxOax8YN/1gFfB VHTDSeEpOfVgqxoYLPFuWgDYJF8s+qhguk+k66+NvSyjFUzYwpo1Zr3nHotFYWlnmy xBbyp2pE/hx0w== From: Nathan Chancellor To: Masahiro Yamada Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Nick Desaulniers , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev, Nathan Chancellor Subject: [PATCH v2 2/2] kbuild: Add -Werror=ignored-optimization-argument to CLANG_FLAGS Date: Thu, 16 Sep 2021 11:40:17 -0700 Message-Id: <20210916184017.1881473-3-nathan@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210916184017.1881473-1-nathan@kernel.org> References: <20210916184017.1881473-1-nathan@kernel.org> MIME-Version: 1.0 X-Patchwork-Bot: notify Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Similar to commit 589834b3a009 ("kbuild: Add -Werror=unknown-warning-option to CLANG_FLAGS"). Clang ignores certain GCC flags that it has not implemented, only emitting a warning: $ echo | clang -fsyntax-only -falign-jumps -x c - clang-14: warning: optimization flag '-falign-jumps' is not supported [-Wignored-optimization-argument] When one of these flags gets added to KBUILD_CFLAGS unconditionally, all subsequent cc-{disable-warning,option} calls fail because -Werror was added to these invocations to turn the above warning and the equivalent -W flag warning into errors. To catch the presence of these flags earlier, turn -Wignored-optimization-argument into an error so that the flags can either be implemented or ignored via cc-option and there are no more weird errors. Reviewed-by: Nick Desaulniers Signed-off-by: Nathan Chancellor --- scripts/Makefile.clang | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang index 4cce8fd0779c..51fc23e2e9e5 100644 --- a/scripts/Makefile.clang +++ b/scripts/Makefile.clang @@ -29,7 +29,12 @@ CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) else CLANG_FLAGS += -fintegrated-as endif +# By default, clang only warns when it encounters an unknown warning flag or +# certain optimization flags it knows it has not implemented. +# Make it behave more like gcc by erroring when these flags are encountered +# so they can be implemented or wrapped in cc-option. CLANG_FLAGS += -Werror=unknown-warning-option +CLANG_FLAGS += -Werror=ignored-optimization-argument KBUILD_CFLAGS += $(CLANG_FLAGS) KBUILD_AFLAGS += $(CLANG_FLAGS) export CLANG_FLAGS