external/newlib/newlib.cmake

#-------------------------------------------------------------------------------
# Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
#
# SPDX-License-Identifier: BSD-3-Clause
#
#-------------------------------------------------------------------------------

# Determine the number of processes to run while running parallel builds.
# Pass -DPROCESSOR_COUNT=<n> to cmake to override.
if(NOT DEFINED PROCESSOR_COUNT)
	include(ProcessorCount)
	ProcessorCount(PROCESSOR_COUNT)
	set(PROCESSOR_COUNT ${PROCESSOR_COUNT} CACHE STRING "Number of cores to use for parallel builds.")
endif()

set(NEWLIB_URL "https://sourceware.org/git/newlib-cygwin.git" CACHE STRING "newlib repository URL")
set(NEWLIB_REFSPEC "newlib-4.1.0" CACHE STRING "newlib git refspec")
set(NEWLIB_INSTALL_PATH "${CMAKE_CURRENT_BINARY_DIR}/newlib_install" CACHE PATH "newlib installation directory")

include(FetchContent)

# Checking git
find_program(GIT_COMMAND "git")
if (NOT GIT_COMMAND)
	message(FATAL_ERROR "Please install git")
endif()

# Fetching newlib
FetchContent_Declare(
	newlib
	GIT_REPOSITORY ${NEWLIB_URL}
	GIT_TAG ${NEWLIB_REFSPEC}
	GIT_SHALLOW TRUE
	PATCH_COMMAND git stash
		COMMAND git am ${CMAKE_CURRENT_LIST_DIR}/0001-Allow-aarch64-linux-gcc-to-compile-bare-metal-lib.patch
		COMMAND git reset HEAD~1
)

# FetchContent_GetProperties exports newlib_SOURCE_DIR and newlib_BINARY_DIR variables
FetchContent_GetProperties(newlib)
if(NOT newlib_POPULATED)
	message(STATUS "Fetching newlib")
	FetchContent_Populate(newlib)
endif()

# Extracing compiler prefix without the trailing hyphen from the C compiler name
get_filename_component(COMPILER_PATH ${CMAKE_C_COMPILER} DIRECTORY)
get_filename_component(COMPILER_NAME ${CMAKE_C_COMPILER} NAME)
string(REGEX REPLACE "([^-]+-[^-]+-[^-]+).*" "\\1" COMPILER_PREFIX ${COMPILER_NAME})

# Newlib configure step
# CC env var must be unset otherwise configure will assume the cross compiler is the host compiler
# The configure options are set to minimize code size and memory usage.
execute_process(COMMAND
	${CMAKE_COMMAND} -E env --unset=CC PATH=${COMPILER_PATH}:$ENV{PATH} ./configure
		--target=${COMPILER_PREFIX}
		--prefix=${NEWLIB_INSTALL_PATH}
		--enable-newlib-nano-formatted-io
		--enable-newlib-nano-malloc
		--enable-lite-exit
		--enable-newlib-reent-small
		--enable-newlib-global-atexit
		--disable-multilib
		CFLAGS_FOR_TARGET=-fpic
		LDFLAGS_FOR_TARGET=-fpie
	WORKING_DIRECTORY
		${newlib_SOURCE_DIR}
	RESULT_VARIABLE _newlib_error
)

if (_newlib_error)
	message(FATAL_ERROR "Configuration step of newlib failed with ${_newlib_error}.")
endif()

# Newlib build step
execute_process(COMMAND
	${CMAKE_COMMAND} -E env --unset=CC PATH=${COMPILER_PATH}:$ENV{PATH} make -j${PROCESSOR_COUNT}
	WORKING_DIRECTORY
		${newlib_SOURCE_DIR}
	RESULT_VARIABLE _newlib_error
)

if (_newlib_error)
	message(FATAL_ERROR "Build step of newlib failed with ${_newlib_error}.")
endif()

# Newlib install step
execute_process(COMMAND
	${CMAKE_COMMAND} -E env --unset=CC PATH=${COMPILER_PATH}:$ENV{PATH} make install
	WORKING_DIRECTORY
		${newlib_SOURCE_DIR}
	RESULT_VARIABLE _newlib_error
)

if (_newlib_error)
	message(FATAL_ERROR "Install step of newlib failed with ${_newlib_error}.")
endif()

# libc
add_library(c STATIC IMPORTED)
set_property(TARGET c PROPERTY IMPORTED_LOCATION "${NEWLIB_INSTALL_PATH}/${COMPILER_PREFIX}/lib/libc.a")
set_property(TARGET c PROPERTY INTERFACE_INCLUDE_DIRECTORIES "${NEWLIB_INSTALL_PATH}/${COMPILER_PREFIX}/include")

# libnosys
add_library(nosys STATIC IMPORTED)
set_property(TARGET nosys PROPERTY IMPORTED_LOCATION "${NEWLIB_INSTALL_PATH}/${COMPILER_PREFIX}/lib/libnosys.a")
set_property(TARGET nosys PROPERTY INTERFACE_INCLUDE_DIRECTORIES "${NEWLIB_INSTALL_PATH}/${COMPILER_PREFIX}/include")