From 7f75fd1d83ae1eabf81b933b972bb7217972cba2 Mon Sep 17 00:00:00 2001
From: Bertrand Jacquin <bertrand@jacquin.bzh>
Date: Sun, 21 Feb 2021 01:33:10 +0000
Subject: eclass/linux-build: add support for llvm

---
 eclass/linux-build.eclass | 103 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 85 insertions(+), 18 deletions(-)

(limited to 'eclass')

diff --git a/eclass/linux-build.eclass b/eclass/linux-build.eclass
index 92f281f6..5d0711fa 100644
--- a/eclass/linux-build.eclass
+++ b/eclass/linux-build.eclass
@@ -17,10 +17,12 @@ esac
 
 ETYPE="sources"
 
-inherit savedconfig kernel-2
+PYTHON_COMPAT=( python3_{7..9} )
+
+inherit savedconfig llvm python-any-r1 kernel-2 eapi7-ver
 detect_version
 
-EXPORT_FUNCTIONS pkg_setup src_prepare src_compile src_install pkg_postinst
+EXPORT_FUNCTIONS pkg_pretend pkg_setup src_prepare src_compile src_install pkg_postinst
 
 : ${LINUX_BUILD_MOD_SIG_DAYS:=365}
 : ${LINUX_BUILD_MOD_SIG_KEY_ALG:=rsa}
@@ -38,14 +40,28 @@ BUILDDIR="${WORKDIR}/build"
 KV_EXTRA="${EXTRAVERSION}"
 S="${SRCDIR}"
 
-IUSE="build source"
+IUSE="build llvm source"
 REQUIRED_USE="symlink? ( source )"
 
 DEPEND="${DEPEND}
 	sys-devel/bc
 	sys-apps/diffutils
 	sys-apps/kmod
-	virtual/libelf"
+	virtual/libelf
+	llvm? (
+		|| (
+			(
+				sys-devel/clang:10
+				sys-devel/llvm:10
+				=sys-devel/lld-10*
+			)
+			(
+				sys-devel/clang:11
+				sys-devel/llvm:11
+				=sys-devel/lld-11*
+			)
+		)
+	)"
 
 # @FUNCTION: _linux-build_configval
 # @INTERNAL
@@ -192,7 +208,25 @@ _linux-build_pkg_setup-build() {
 linux-build_pkg_setup() {
 	kernel-2_pkg_setup
 
-	use build && _linux-build_pkg_setup-build
+	if use build ; then
+		use llvm && llvm_pkg_setup
+		python-any-r1_pkg_setup
+		_linux-build_pkg_setup-build
+	fi
+}
+
+linux-build_pkg_pretend() {
+	if use llvm ; then
+		case "${ARCH}" in
+			arm|arm64) ;;
+			amd64|x86) ;;
+			*) die "USE=llvm is not supported by ARCH=${ARCH}" ;;
+		esac
+
+		if ver_test -lt 5.10 ; then
+			die "USE=llvm is supported starting with ${CATEGORY}/${PN}-5.10"
+		fi
+	fi
 }
 
 _linux-build_src_prepare_build() {
@@ -453,16 +487,26 @@ _linux-build_src_prepare_build() {
 		--ignore-matching-lines '^$'
 		--ignore-matching-lines '^#'
 
-		# GCC vs Clang
-		--ignore-matching-lines '^CONFIG_CC_IS_GCC='
-		--ignore-matching-lines '^CONFIG_CC_IS_CLANG='
-		--ignore-matching-lines '^CONFIG_GCC_VERSION='
-		--ignore-matching-lines '^CONFIG_CLANG_VERSION='
-		--ignore-matching-lines '^CONFIG_PLUGIN_HOSTCC='
-		--ignore-matching-lines '^CONFIG_CC_HAS_'
+		# Compiler
+		--ignore-matching-lines '^CONFIG_CC_VERSION_TEXT='
+		--ignore-matching-lines '^CONFIG_CC_HAS_[A-Z_]*='
+		--ignore-matching-lines '^CONFIG_HAVE_[A-Z_]*_COMPILER='
 
 		# GCC only
+		--ignore-matching-lines '^CONFIG_CC_IS_GCC='
+		--ignore-matching-lines '^CONFIG_GCC_VERSION='
+		--ignore-matching-lines '^CONFIG_LD_VERSION='
+		--ignore-matching-lines '^CONFIG_PLUGIN_HOSTCC=' # Removed in v5.7
+		--ignore-matching-lines '^CONFIG_GCC_PLUGINS='
+		--ignore-matching-lines '^CONFIG_GCC_PLUGIN_[A-Z_]*='
 		--ignore-matching-lines '^CONFIG_KASAN_STACK='
+
+		# Clang only
+		--ignore-matching-lines '^CONFIG_CC_IS_CLANG='
+		--ignore-matching-lines '^CONFIG_LD_IS_LLD='
+		--ignore-matching-lines '^CONFIG_CLANG_VERSION='
+		--ignore-matching-lines '^CONFIG_LLD_VERSION='
+		--ignore-matching-lines '^CONFIG_TOOLS_SUPPORT_RELR='
 	)
 
 	if ! diff -q "${_diff_opts[@]}" "${BUILDDIR}/.config.old" "${BUILDDIR}/.config" ; then
@@ -489,11 +533,31 @@ linux-build_src_prepare() {
 	)
 
 	copt=(
-		HOSTCC="$(tc-getBUILD_CC)" HOSTCXX="$(tc-getBUILD_CXX)"
-		HOSTLD="$(tc-getBUILD_LD)"
-		HOSTAR="$(tc-getBUILD_AR)"
-
+		ARCH="$(tc-arch-kernel)" SUBARCH="$(tc-arch-kernel)"
 		CROSS_COMPILE="${CHOST}-"
+	)
+
+	if use llvm ; then
+		copt+=(
+			LLVM=1 LLVM_IAS=1
+			HOSTCC="${CBUILD}-clang" HOSTCXX="${CBUILD}-clang++"
+			HOSTLD="ld.lld"
+			HOSTAR="llvm-ar"
+			CC="${CHOST}-clang" CXX="${CHOST}-clang++"
+			LD="ld.lld"
+			AR="llvm-ar"
+			AS="llvm-as" # Removed in v5.7
+			NM="llvm-nm"
+			OBJCOPY="llvm-objcopy"
+			OBJDUMP="llvm-objdump"
+			READELF="llvm-readelf"
+			STRIP="llvm-strip"
+		)
+	else
+		copt+=(
+			HOSTCC="$(tc-getBUILD_CC)" HOSTCXX="$(tc-getBUILD_CXX)"
+			HOSTLD="$(tc-getBUILD_LD)"
+			HOSTAR="$(tc-getBUILD_AR)"
 			CC="$(tc-getCC)" CXX="$(tc-getCXX)"
 			LD="$(tc-getLD)"
 			AR="$(tc-getAR)"
@@ -502,10 +566,13 @@ linux-build_src_prepare() {
 			OBJCOPY="$(tc-getOBJCOPY)"
 			OBJDUMP="$(tc-getOBJDUMP)"
 			READELF="$(tc-getREADELF)"
-			PKG_CONFIG="$(tc-getPKG_CONFIG)"
 			STRIP="$(tc-getSTRIP)"
+		)
+	fi
 
-		ARCH="$(tc-arch-kernel)" SUBARCH="$(tc-arch-kernel)"
+	copt+=(
+		PKG_CONFIG="$(tc-getPKG_CONFIG)"
+		PYTHON3="${PYTHON}"
 	)
 
 	vopt=(
-- 
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