From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751954AbaBZBJb (ORCPT ); Tue, 25 Feb 2014 20:09:31 -0500 Received: from mail-pb0-f43.google.com ([209.85.160.43]:61848 "EHLO mail-pb0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751491AbaBZBJ0 (ORCPT ); Tue, 25 Feb 2014 20:09:26 -0500 From: behanw@converseincode.com To: mmarek@suse.cz, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, sparse@chrisli.org Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sparse@vger.kernel.org, torvalds@linux-foundation.org, dwmw2@infradead.org, pageexec@freemail.hu, Behan Webster , =?UTF-8?q?Jan-Simon=20M=C3=B6ller?= , Mark Charlebois Subject: [PATCH 1/5] kbuild: LLVMLinux: Add Kbuild support for building kernel with Clang Date: Tue, 25 Feb 2014 17:08:39 -0800 Message-Id: <1393376923-21892-2-git-send-email-behanw@converseincode.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1393376923-21892-1-git-send-email-behanw@converseincode.com> References: <1393376923-21892-1-git-send-email-behanw@converseincode.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Behan Webster Add support to toplevel Makefile for compiling with clang, both for HOSTCC and CC. Use cc-option to prevent gcc option from breaking clang, and from clang options from breaking gcc. Clang 3.4 semantics are the same as gcc semantics for unsupported flags. For unsupported warnings clang 3.4 returns true but shows a warning and gcc shows a warning and returns false. Signed-off-by: Behan Webster Signed-off-by: Jan-Simon Möller Signed-off-by: Mark Charlebois Cc: PaX Team --- Makefile | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 831b36a..c4ab30d 100644 --- a/Makefile +++ b/Makefile @@ -247,6 +247,15 @@ HOSTCXX = g++ HOSTCFLAGS = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer HOSTCXXFLAGS = -O2 +ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1) +HOSTCOMPILER := clang +HOSTCFLAGS += -Wno-unused-value -Wno-unused-parameter \ + -Wno-missing-field-initializers -fno-delete-null-pointer-checks +else +HOSTCOMPILER := gcc +endif +export HOSTCOMPILER + # Decide whether to build built-in, modular, or both. # Normally, just do built-in. @@ -323,6 +332,12 @@ endif export quiet Q KBUILD_VERBOSE +ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1) +COMPILER := clang +else +COMPILER := gcc +endif +export COMPILER # Look for make include files relative to root of kernel src MAKEFLAGS += --include-dir=$(srctree) @@ -382,7 +397,7 @@ KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -fno-common \ -Werror-implicit-function-declaration \ -Wno-format-security \ - -fno-delete-null-pointer-checks + $(call cc-option,-fno-delete-null-pointer-checks,) KBUILD_AFLAGS_KERNEL := KBUILD_CFLAGS_KERNEL := KBUILD_AFLAGS := -D__ASSEMBLY__ @@ -620,9 +635,24 @@ else endif KBUILD_CFLAGS += $(stackp-flag) +ifeq ($(COMPILER),clang) +KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) +KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,) +KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable) +KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) +KBUILD_CFLAGS += $(call cc-disable-warning, gnu) +# Quiet clang warning: comparison of unsigned expression < 0 is always false +KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) +# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the +# source of a reference will be _MergedGlobals and not on of the whitelisted names. +# See modpost pattern 2 +KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) +else + # This warning generated too much noise in a regular build. # Use make W=1 to enable this warning (see scripts/Makefile.build) KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) +endif ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls -- 1.8.3.2