#-------------------------------------------------------------------------------
# Copyright (c) 2019-2022, Arm Limited and Contributors. All rights reserved.
#
# SPDX-License-Identifier: BSD-3-Clause
#
#-------------------------------------------------------------------------------

#[===[.rst:
Compiler abstraction for GCC
----------------------------

.. cmake:variable:: CROSS_COMPILE

	A ';' separated GCC prefix triplets to use when searching for the cross-compiler.
	(i.e. ``aarch64-none-elf;aarch64-elf``).
	The variable can be set on the command line with ``-DCROSS_COMPILE=<value>`` or in the
	environment. If both is specified, command line takes precedence.

.. cmake:variable:: LIBGCC_PATH

	An absolute path to specify the location of the gcc specific library.  The name
	of the library is libgcc.a.  Note that it must be the full path with library name.
	The variable can be set on the command line with ``-DLIBGCC_PATH=<value>`` or in the
	environment. If both is specified, command line takes precedence.

.. cmake:variable:: LIBGCC_INCLUDE_DIRS

	A semicolon separated list of absolute paths to specify the location of gcc specific header
	files. The variable can be set on the command line with ``-DLIBGCC_INCLUDE_DIRS=<value>``
	or in the environment. If both is specified, command line takes precedence.

.. cmake:variable:: LIBGCC_LOCATE_CFLAGS

	The compiler options used when searching for the gcc library (libgcc.a).
	Setting the value is optional.
	The variable can be set on the command line with ``-DLIBGCC_LOCATE_CFLAGS=<value>`` or
	in the environment.

#]===]

include_guard(DIRECTORY)

if(NOT CROSS_COMPILE AND NOT DEFINED ENV{CROSS_COMPILE})
	message(FATAL_ERROR "'CROSS_COMPILE' is not defined. Set it to the gcc prefix triplet, ie. cmake <..>-DCROSS_COMPILE=aarch64-elf-")
endif()

set(CROSS_COMPILE $ENV{CROSS_COMPILE} CACHE STRING "Prefix of the cross-compiler commands")

#Generate a list of tool names to look for. Store the result in CMAKE_<lang>_COMPILER.
function(gcc_find_tool NAME LANG)
	string(REGEX REPLACE "([^;]+);" "\\1${NAME};\\1${NAME}.exe;" _gcc_names "${CROSS_COMPILE};")
	find_program(_cross_compile_gcc NAMES ${_gcc_names} REQUIRED)
	if (NOT _cross_compile_gcc)
		string(REPLACE ";" " " _msg "${_gcc_names}")
		message(FATAL_ERROR "Failed to find ${NAME} with the names: ${_msg}")
	endif()
	set(CMAKE_${LANG}_COMPILER ${_cross_compile_gcc} CACHE STRING "${LANG} compiler executable.")
endfunction()

gcc_find_tool(gcc C)
gcc_find_tool(g++ CXX)

#Official solution to disable compiler checks
set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)

#By default when INTERFACE_INCUDES of libraries linked to an exe are treated
#as system includes. gcc-arm-8.2-2019.01-i686-mingw32-aarch64-elf (gcc 8.2.1) will
#set C linkage o these files, which will result in compilation errors for C++ projects.
#This setting fixes that.
set(CMAKE_NO_SYSTEM_FROM_IMPORTED True)

#[===[.rst:
.. cmake:command:: compiler_preprocess_file

  .. code-block:: cmake

	compiler_preprocess_file(SRC file.c DST file_pp.c)
	compiler_preprocess_file(SRC file.c DST file_pp.c
							 DEFINES USE_LIB INCLUDES include/lib)

  Run the preprocessor on a file and save the output to another file. Optionally
  provide defines and include paths to the preprocessor.

  Inputs:

  ``SRC``
	Name of the source file to preprocess.

  ``DST``
	Where to write the preprocessed output.

  ``DEFINES`` (multi, optional)
	Definitions for the preprocessor.

  ``INCLUDES`` (multi, optional)
	Include paths for the preprocessor.

#]===]
function(compiler_preprocess_file)
	set(_OPTIONS_ARGS)
	set(_ONE_VALUE_ARGS SRC DST)
	set(_MULTI_VALUE_ARGS DEFINES INCLUDES)
	cmake_parse_arguments(_MY_PARAMS "${_OPTIONS_ARGS}" "${_ONE_VALUE_ARGS}" "${_MULTI_VALUE_ARGS}" ${ARGN})

	check_args(compiler_preprocess_file SRC DST)

	set(_flags "")
	if(_MY_PARAMS_DEFINES)
		list(TRANSFORM _MY_PARAMS_DEFINES PREPEND -D)
		list(APPEND _flags ${_MY_PARAMS_DEFINES})
	endif()
	if(_MY_PARAMS_INCLUDES)
		list(TRANSFORM _MY_PARAMS_INCLUDES PREPEND -I)
		list(APPEND _flags ${_MY_PARAMS_INCLUDES})
	endif()

	add_custom_command(
		DEPENDS ${_MY_PARAMS_SRC} OUTPUT ${_MY_PARAMS_DST}
		COMMAND ${CMAKE_C_COMPILER} -E -P -x assembler-with-cpp ${_flags}
				${_MY_PARAMS_SRC} -o ${_MY_PARAMS_DST}
	)
endfunction()

#[===[.rst:
.. cmake:command:: compiler_set_linker_script

  .. code-block:: cmake

	compiler_set_linker_script(TARGET foo FILE foo.ld.S)
	compiler_set_linker_script(TARGET foo FILE foo.ld.S DEF USE_LIB INC include/lib)

  Set linker script for a target. The function adds an LDFLAG using the
  toolchain specific syntax to the TARGET_linker_script group, which is applied
  onto the target by the caller function. FILE will be preprocessed, optionally
  defines and/or includes can be provided using DEF/INC arguments.

  Inputs:

  ``TARGET``
	Name of the target.

  ``FILE``
	Linker script file for the target.

  ``DEF`` (multi, optional)
	Defines for the linker script preprocessor.

  ``INC`` (multi, optional)
	Include paths for the linker script preprocessor.

#]===]
function(compiler_set_linker_script)
	set(_OPTIONS_ARGS)
	set(_ONE_VALUE_ARGS TARGET FILE)
	set(_MULTI_VALUE_ARGS DEF INC)
	cmake_parse_arguments(_MY_PARAMS "${_OPTIONS_ARGS}" "${_ONE_VALUE_ARGS}" "${_MULTI_VALUE_ARGS}" ${ARGN})

	check_args(compiler_set_linker_script TARGET FILE)

	get_filename_component(_src "${_MY_PARAMS_FILE}" ABSOLUTE)
	get_filename_component(_src_ext "${_MY_PARAMS_FILE}" EXT)
	set(_dst "${CMAKE_BINARY_DIR}/${_MY_PARAMS_TARGET}.ld")

	if(NOT ("${_src_ext}" STREQUAL ".ld" OR "${_src_ext}" STREQUAL ".ld.S"))
		message(WARNING "compiler_set_linker_script(): extension mismatch '${_src}'")
	endif()

	compiler_preprocess_file(
		SRC ${_src}
		DST ${_dst}
		DEFINES ${_MY_PARAMS_DEF} __LINKER__
		INCLUDES ${_MY_PARAMS_INC}
	)

	add_custom_target("${_MY_PARAMS_TARGET}_ld" DEPENDS "${_dst}")
	add_dependencies("${_MY_PARAMS_TARGET}" "${_MY_PARAMS_TARGET}_ld")

	target_link_options(${_MY_PARAMS_TARGET} PRIVATE "-Wl,--script=${_dst}")
	set_target_properties(${_MY_PARAMS_TARGET} PROPERTIES LINK_DEPENDS "${_dst}")
endfunction()

#[===[.rst:
.. cmake:command:: compiler_generate_binary_output

  .. code-block:: cmake

	compiler_generate_binary_output(TARGET <name> RES <var>)

  Generate binary output for the target. The function converts the output
  executable into bin file using toolchain specific syntax.

  Inputs:

  ``TARGET``
	Name of the target.

  Outputs:

  ``RES``
	Full patch to output file.

#]===]
function(compiler_generate_binary_output)
	set(options)
	set(oneValueArgs TARGET NAME RES)
	set(multiValueArgs)
	cmake_parse_arguments(MY "${options}" "${oneValueArgs}"
						"${multiValueArgs}" ${ARGN} )
	add_custom_command(
		TARGET ${MY_TARGET} POST_BUILD
		COMMAND ${CMAKE_OBJCOPY} -O binary
				$<TARGET_FILE:${MY_TARGET}>
				$<TARGET_FILE_DIR:${MY_TARGET}>/${MY_NAME})
	if (MY_RES)
		set(${MY_RES} $<TARGET_FILE_DIR:${MY_TARGET}>/${MY_NAME} PARENT_SCOPE)
	endif()

endfunction()

#[===[.rst:
.. cmake:command:: compiler_generate_stripped_elf

  .. code-block:: cmake

	compiler_generate_stripped_elf(TARGET foo NAME foo.stripped.elf RES var)

  Strip all symbols that are not needed for relocation processing and return the location
  of the result.

  Inputs:

  ``TARGET``
	Name of the target.

  ``NAME``
	Name of output file

  Outputs:

  ``RES``
	Name of variable to store the full path of the stripped executable.

#]===]

function(compiler_generate_stripped_elf)
	set(options)
	set(oneValueArgs TARGET NAME RES)
	set(multiValueArgs)
	cmake_parse_arguments(MY "${options}" "${oneValueArgs}"
						"${multiValueArgs}" ${ARGN} )

	add_custom_command(
		TARGET ${MY_TARGET} POST_BUILD
		COMMAND ${CMAKE_OBJCOPY} --strip-unneeded
				$<TARGET_FILE:${MY_TARGET}>
				$<TARGET_FILE_DIR:${MY_TARGET}>/${MY_NAME})
	if (MY_RES)
		set(${MY_RES} $<TARGET_FILE_DIR:${MY_TARGET}>/${MY_NAME} PARENT_SCOPE)
	endif()
endfunction()

#[===[.rst:
.. cmake:command:: gcc_get_lib_location

  .. code-block:: cmake

	gcc_get_lib_location(TARGET foo NAME foo.stripped.elf RES var)

  Query the location of a specific library part of the GCC binary release. Can
  be used to find built in libraries like libgcc.a when i.w. -nostdlib option
  is used.

  The function uses the :variable:`LIBGCC_LOCATE_CFLAGS`.

  Inputs:

  ``LIBRARY_NAME``
	Name of the library to search for.

  Outputs:

  ``RES``
	Name of variable to store the full path of the library.

#]===]
function(gcc_get_lib_location)
	set(options)
	set(oneValueArgs LIBRARY_NAME RES)
	set(multiValueArgs)
	cmake_parse_arguments(MY "${options}" "${oneValueArgs}"
						"${multiValueArgs}" ${ARGN} )

	if (DEFINED ENV{LIBGCC_LOCATE_CFLAGS})
		set(LIBGCC_LOCATE_CFLAGS $ENV{LIBGCC_LOCATE_CFLAGS} CACHE STRING "GCC library search options" )
	endif()

	execute_process(
		COMMAND ${CMAKE_C_COMPILER} ${LIBGCC_LOCATE_CFLAGS} "--print-file-name=${MY_LIBRARY_NAME}"
		OUTPUT_VARIABLE _RES
		RESULT_VARIABLE _GCC_ERROR_CODE
		OUTPUT_STRIP_TRAILING_WHITESPACE
		)

	if(_GCC_ERROR_CODE GREATER 0)
		message(WARNING "GCC (${CMAKE_C_COMPILER}) invocation failed, cannot determine location of library \"${MY_LIBRARY_NAME}\".")
		set(_RES "${LIBRARY_NAME}-NOTFOUND")
	endif()

	if (NOT IS_ABSOLUTE "${_RES}")
		message(WARNING "GCC (${CMAKE_C_COMPILER}) failed to return the location of file \"${MY_LIBRARY_NAME}\".")
		set(_RES "${LIBRARY_NAME}-NOTFOUND")
	endif()

	set(${MY_RES} ${_RES} PARENT_SCOPE)
endfunction()


#[===[.rst:
.. cmake:command:: compiler_set_freestanding

  .. code-block:: cmake

	compiler_set_freestanding(TARGET foo)

  	Configure the target specified for "freestanging" compilation mode. Please see [1] for more information.
	This will configure the target:
	  - to block access to the "built in" standard library and its headers
	  - link compiler specific libraries
	  - add include paths to compiler specific headers

	All settings will be PUBLIC or INTERFACE (for imported targets) and thus will take effect on targets
	depending on the configured one.

	The function uses and manipulates the following CACHE variables:
	  - :variable:`LIBGCC_PATH`
	  - :variable:`LIBGCC_INCLUDE_DIRS`

	CMake has a spacial behavior which needs a workaround. CMake is automatically filtering out built in compiler
	include paths from the compiler command line.
	As a workaround, compiler specific headers are copied to the build directory and set include path to the new
	location.

	Limitations:
	  - Inheritance of target settings may be problematic. Compiling components in "freestanding" mode may put
	    restrictions on reusing these. When such components are installed, the "freestanding" nature shall be
		propagated to dependencies. This is not tested or implemented.

	1: https://wiki.osdev.org/Implications_of_writing_a_freestanding_C_project
	2: https://gitlab.kitware.com/cmake/cmake/-/issues/19227

  Inputs:

  ``TARGET``
	Name of the target to configure.

  Outputs:

  N/A

#]===]
function(compiler_set_freestanding)
	set(options)
	set(oneValueArgs TARGET)
	set(multiValueArgs)
	cmake_parse_arguments(MY "${options}" "${oneValueArgs}"
						"${multiValueArgs}" ${ARGN} )

	# Validate parameters
	if (NOT DEFINED MY_TARGET)
		message(FATAL_ERROR "Mandatory parameter TARGET is missing!")
	endif()

	# Set INTERFACE options for imported targets and PUBLIC otherwise.
	get_property(_is_imported_target TARGET ${MY_TARGET} PROPERTY IMPORTED SET)
	if (_is_imported_target)
		set(_option_type INTERFACE)
	else()
		set(_option_type PUBLIC)
	endif()

	### Get the location of libgcc.a
	# Copy values from environment if present. Note: if the value is already in the CACHE, this set will have no effect.
	if(DEFINED ENV{LIBGCC_PATH})
		set(LIBGCC_PATH $ENV{LIBGCC_PATH} CACHE PATH "location of libgcc.a")
	endif()
	if (NOT DEFINED LIBGCC_PATH)
		gcc_get_lib_location(LIBRARY_NAME "libgcc.a" RES _TMP_VAR)

		if (NOT _TMP_VAR)
			message(FATAL_ERROR "Location of libgcc.a can not be determined. Please set LIBGCC_PATH on the command"
					" line or in the environment.")
		endif()
		set(LIBGCC_PATH ${_TMP_VAR} CACHE PATH "location of libgcc.a")
		unset(_TMP_VAR)
	endif()

	# Validate LIBGCC_PATH
	if(NOT EXISTS "${LIBGCC_PATH}" OR IS_DIRECTORY "${LIBGCC_PATH}")
		message(FATAL_ERROR "LIBGCC_PATH \"${LIBGCC_PATH}\" must be the full path of a library file."
							" Either set LIBGCC_PATH on the command line (or in the environment), or fix the existing"
							" value.")
	endif()
	message(STATUS "libgcc.a for target \"${MY_TARGET}\" is used from ${LIBGCC_PATH}")

	### Get the location of libgcc specific header files.
	# Copy values from environment if present. Note: if the value is already in the CACHE, this set will have no effect.
	if(DEFINED ENV{LIBGCC_INCLUDE_DIRS})
		set(LIBGCC_INCLUDE_DIRS $ENV{LIBGCC_INCLUDE_DIRS} CACHE STRING "GCC specific include PATHs")
	endif()
	if(NOT DEFINED LIBGCC_INCLUDE_DIRS)
		# We can get the correct path if we ask for a location without a library name
		gcc_get_lib_location(LIBRARY_NAME "" RES _TMP_VAR)

		if (NOT _TMP_VAR)
			message(FATAL_ERROR "Location of GCC specific include PATHs can not be determined. Please set"
					" LIBGCC_INCLUDE_DIRS on the command line or in the environment.")
		endif()

		set(LIBGCC_INCLUDE_DIRS
			"${_TMP_VAR}/include"
			"${_TMP_VAR}/include-fixed" CACHE STRING "GCC specific include PATHs")
		unset(_TMP_VAR)
	endif()

	# There is no way to stop cmake from filtering out built in compiler include paths
	# from compiler command line (see https://gitlab.kitware.com/cmake/cmake/-/issues/19227).
	# As a workaround copy headers to build directory and set include path to the new
	# location.
	# Also validate locations.
	if (NOT GCC_INCLUDES_MOVED)
		foreach(_dir IN LISTS LIBGCC_INCLUDE_DIRS)
			if(NOT IS_DIRECTORY "${_dir}")
				message(FATAL_ERROR "GCC specific include PATH \"${_dir}\" does not exist.")
			endif()

			file(COPY "${_dir}" DESTINATION "${CMAKE_CURRENT_BINARY_DIR}/gcc-include")
			get_filename_component(_TMP_VAR "${_dir}" NAME)
			list(APPEND _gcc_include_dirs "${CMAKE_CURRENT_BINARY_DIR}/gcc-include/${_TMP_VAR}")
			message(STATUS "Compiler specific include path \"${_dir}\" mirrored to"
							"  \"${CMAKE_CURRENT_BINARY_DIR}/gcc-include/${_TMP_VAR}\".")
		endforeach()
		unset(_TMP_VAR)
		set(GCC_INCLUDES_MOVED True CACHE BOOL "GCC include files are already copied.")
		mark_as_advanced(GCC_INCLUDES_MOVED)
		# Fix the variable in the CACHE.
		set(LIBGCC_INCLUDE_DIRS ${_gcc_include_dirs} CACHE STRING "GCC specific include PATHs" FORCE)
	endif()

	# Configure the target for freestanding mode.
	target_compile_options(${MY_TARGET} ${_option_type} "-nostdinc")
	target_include_directories(${MY_TARGET} SYSTEM ${_option_type} ${LIBGCC_INCLUDE_DIRS})
	target_link_options(${MY_TARGET} ${_option_type} "-nostdlib" "-nostartfiles")
	target_link_libraries(${MY_TARGET} ${_option_type} "${LIBGCC_PATH}")
endfunction()