OUTPUT = $(CURDIR)/output

LLVM_SRCDIR = LLVM_SRCDIR_not_set
MUSL_SRCDIR = MUSL_SRCDIR_not_set

TARGETS = \
	aarch64-linux-musleabi \
	armv7-linux-musleabi \
	armv7-linux-musleabihf \
	armv7m-linux-musleabi \
	armv7m-linux-musleabihf \
	x86_64-linux-musl \
	# end

DEFAULT_TARGET = x86_64-linux-musl

TOOLS = \
	llvm-ar \
	llvm-nm \
	llvm-objcopy \
	llvm-objdump \
	llvm-ranlib \
	llvm-size \
	llvm-strip \
	# end

-include config.mak

# TODO: determine LLVM_TARGETS_TO_BUILD from TARGETS?
FULL_LLVM_CONFIG = $(LLVM_CONFIG) \
	-DCLANG_DEFAULT_CXX_STDLIB=libc++ \
	-DCLANG_DEFAULT_LINKER=lld \
	-DCLANG_DEFAULT_OBJCOPY=llvm-objcopy \
	-DCLANG_DEFAULT_RTLIB=compiler-rt \
	-DCMAKE_BUILD_TYPE=MinSizeRel \
	-DCMAKE_INSTALL_PREFIX=/clang \
	-DDEFAULT_SYSROOT=../../TARGET \
	-DLLVM_BUILTIN_TARGETS='$(subst $(subst ,, ),;,$(TARGETS))' \
	-DLLVM_DEFAULT_TARGET_TRIPLE=$(DEFAULT_TARGET) \
	-DLLVM_DISTRIBUTION_COMPONENTS='clang;lld;LTO;$(subst $(subst ,, ),;,$(TOOLS))' \
	-DLLVM_ENABLE_PROJECTS='clang;lld' \
	-DLLVM_ENABLE_RUNTIMES='compiler-rt;libcxx;libcxxabi;libunwind' \
	-DLLVM_INSTALL_TOOLCHAIN_ONLY=ON \
	-DLLVM_RUNTIME_TARGETS='$(subst $(subst ,, ),;,$(TARGETS))' \
	-DLLVM_TARGETS_TO_BUILD='AArch64;ARM;Mips;PowerPC;X86' \
	$(foreach t,$(TARGETS),-DBUILTINS_$(t)_CMAKE_SYSROOT=$(CURDIR)/obj_sysroot/$(t)) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_CMAKE_CXX_FLAGS='-L$(CURDIR)/obj_musl/$(t)/lib -B$(CURDIR)/obj_musl/$(t)/lib -Qunused-arguments') \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_CMAKE_C_FLAGS='-L$(CURDIR)/obj_musl/$(t)/lib -B$(CURDIR)/obj_musl/$(t)/lib -Qunused-arguments') \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_CMAKE_SYSROOT=$(CURDIR)/obj_sysroot/$(t)) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_COMPILER_RT_BUILD_LIBFUZZER=OFF) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_COMPILER_RT_BUILD_SANITIZERS=OFF) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_COMPILER_RT_BUILD_XRAY=OFF) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_LIBCXXABI_USE_COMPILER_RT=ON) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_LIBCXXABI_USE_LLVM_UNWINDER=ON) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_LIBCXX_HAS_MUSL_LIBC=ON) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_LIBCXX_USE_COMPILER_RT=ON) \
	$(foreach t,$(TARGETS),-DRUNTIMES_$(t)_LIBUNWIND_USE_COMPILER_RT=ON) \
	# end

all: llvm musl

install: install-llvm install-musl install-kernel-headers install-configs install-symlinks

llvm: | obj_llvm/.lc_built_3
musl: | $(foreach t,$(TARGETS),obj_musl/$(t)/.lc_built)
install-musl: $(foreach t,$(TARGETS),install-musl_$(t))
install-kernel-headers: $(foreach t,$(TARGETS),install-kernel-headers_$(t))
install-configs: $(foreach t,$(TARGETS),install-configs_$(t))
install-symlinks: $(foreach t,$(TARGETS),install-symlinks_$(t))

.PHONY: all llvm musl install-llvm install-musl install-kernel-headers install-configs install-symlinks clean

src_llvm: | $(LLVM_SRCDIR)
	ln -sf $(LLVM_SRCDIR) $@

src_musl: | $(MUSL_SRCDIR)
	ln -sf $(MUSL_SRCDIR) $@

src_kernel_headers: | $(LINUX_SRCDIR)
	ln -sf "$(LINUX_SRCDIR)" $@

%/:
	mkdir -p $@

obj_llvm/.lc_configured: | obj_llvm/ src_llvm
	cd obj_llvm && cmake -G "Unix Makefiles" $(FULL_LLVM_CONFIG) ../src_llvm/llvm
	touch $@

obj_llvm/.lc_built_1: | obj_llvm/.lc_configured
	cd obj_llvm && $(MAKE) distribution
	touch $@

obj_musl/%/.lc_configured: | obj_musl/%/ src_musl obj_llvm/.lc_built_1
	cd obj_musl/$* && ../../src_musl/configure \
		--prefix= \
		--target=$* \
		--disable-wrapper \
		LIBCC=../../obj_llvm/lib/clang/$(LLVM_VER)/lib/$*/libclang_rt.builtins.a \
		CC="../../obj_llvm/bin/clang --target=$*" \
		$(MUSL_CONFIG)
	touch $@

obj_sysroot/%/.lc_headers: | obj_sysroot/ obj_musl/%/.lc_configured
	cd obj_musl/$* && $(MAKE) DESTDIR=$(CURDIR)/obj_sysroot/$* install-headers
	touch $@

obj_llvm/.lc_built_2: | $(foreach t,$(TARGETS),obj_sysroot/$(t)/.lc_headers)
	cd obj_llvm && $(MAKE) builtins
	touch $@

obj_musl/%/.lc_built: | obj_musl/%/.lc_configured obj_llvm/.lc_built_2
	cd obj_musl/$* && $(MAKE) AR=../../obj_llvm/bin/llvm-ar \
				  RANLIB=../../obj_llvm/bin/llvm-ranlib
	touch $@

obj_sysroot/%/.lc_crt_workaround:
	# Some configure tests for llvm runtimes fail without crtbegin and
	# crtend files in the sysroot. The runtimes build generates these files
	# leading to a chicken-egg problem.
	mkdir -p obj_sysroot/$*/lib
	cd obj_sysroot/$*/lib && touch crtbeginT.o crtbeginS.o crtbegin.o crtend.o crtendS.o
	touch $@

obj_kernel_headers/%/.lc_built: | src_kernel_headers
	mkdir -p $(CURDIR)/obj_kernel_headers/$*/staged
	cd src_kernel_headers && $(MAKE) ARCH=$(call fn_linux_arch,$*) O=$(CURDIR)/obj_kernel_headers/$* INSTALL_HDR_PATH=$(CURDIR)/obj_kernel_headers/$*/staged headers_install
	find obj_kernel_headers/$*/staged/include '(' -name .install -o -name ..install.cmd ')' -exec rm {} +
	touch $@

obj_sysroot/%/.lc_linux_headers: | obj_kernel_headers/%/.lc_built
	mkdir -p obj_sysroot/$*/include
	cp -R obj_kernel_headers/$*/staged/include/* obj_sysroot/$*/include

obj_llvm/.lc_built_3: | $(foreach t,$(TARGETS),obj_musl/$(t)/.lc_built \
					       obj_sysroot/$(t)/.lc_crt_workaround \
					       obj_sysroot/$(t)/.lc_linux_headers)
	cd obj_llvm && $(MAKE) runtimes
	touch $@

install-llvm: | obj_llvm/.lc_built_3
	# -j1 because there's a broken dependency in the llvm build somewhere
	#  which often results in missing c++ libraries for some targets
	cd obj_llvm && $(MAKE) -j1 DESTDIR=$(DESTDIR)$(OUTPUT) install-distribution install-builtins install-runtimes

install-musl_%: | obj_musl/%/.lc_built
	cd obj_musl/$* && $(MAKE) $(MUSL_VARS) DESTDIR=$(DESTDIR)$(OUTPUT)/$* install

install-kernel-headers_%: | obj_kernel_headers/%/.lc_built
	mkdir -p $(DESTDIR)$(OUTPUT)/$*/include
	cp -R obj_kernel_headers/$*/staged/include/* $(DESTDIR)$(OUTPUT)/$*/include

install-configs_%: | $(DESDIR)$(OUTPUT)/clang/bin/
	echo "--target=$*" > $(DESTDIR)$(OUTPUT)/clang/bin/$*-clang.cfg
	echo "--target=$* -lc++abi -lunwind" > $(DESTDIR)$(OUTPUT)/clang/bin/$*-clang++.cfg

install-symlinks_%: | $(DESTDIR)$(OUTPUT)/bin/
	cd $(DESTDIR)$(OUTPUT)/bin && ln -sf ../clang/bin/clang $*-clang
	cd $(DESTDIR)$(OUTPUT)/bin && ln -sf ../clang/bin/clang++ $*-clang++
	cd $(DESTDIR)$(OUTPUT)/bin && ln -sf ../clang/bin/clang-cpp $*-clang-cpp
	cd $(DESTDIR)$(OUTPUT)/bin && ln -sf ../clang/bin/ld.lld $*-ld
	$(foreach t,$(TOOLS),cd $(DESTDIR)$(OUTPUT)/bin && ln -sf ../clang/bin/$(t) $*-$(subst llvm-,,$(t);))

clean:
	rm -rf src_* obj_*

# $(call fn_linux_arch,target-triple)
#     Determine linux architecture from target triple
ifeq ($(LINUX_SRCDIR),)
$(error LINUX_SRCDIR is required for llvm libc++ build)
endif
LINUX_ARCH_LIST := $(sort $(notdir $(wildcard $(LINUX_SRCDIR)/arch/*)))
fn_target_arch = $(firstword $(subst -, ,$(1)))
fn_target_arch_mangled = $(patsubst i%86,x86,$(patsubst aarch64%,arm64%,$(call fn_target_arch,$(1))))
fn_linux_arch = $(lastword $(foreach a,$(LINUX_ARCH_LIST),$(if $(filter $(a)%,$(call fn_target_arch_mangled,$(1))),$(a))))

.SECONDARY: