cmake/compiler/clang/target.cmake

# SPDX-License-Identifier: Apache-2.0

# Configuration for host installed clang
#

set(NOSTDINC "")

# Note that NOSYSDEF_CFLAG may be an empty string, and
# set_ifndef() does not work with empty string.
if(NOT DEFINED NOSYSDEF_CFLAG)
  set(NOSYSDEF_CFLAG -undef)
endif()

if(DEFINED TOOLCHAIN_HOME)
  set(find_program_clang_args PATHS ${TOOLCHAIN_HOME} NO_DEFAULT_PATH)
endif()

find_program(CMAKE_C_COMPILER   clang   ${find_program_clang_args})
find_program(CMAKE_CXX_COMPILER clang++ ${find_program_clang_args})

if(NOT "${ARCH}" STREQUAL "posix")
  include(${ZEPHYR_BASE}/cmake/gcc-m-cpu.cmake)
  include(${ZEPHYR_BASE}/cmake/gcc-m-fpu.cmake)

  if("${ARCH}" STREQUAL "arm")
    list(APPEND TOOLCHAIN_C_FLAGS
      -fshort-enums
      )
    list(APPEND TOOLCHAIN_LD_FLAGS
      -fshort-enums
      )

    include(${ZEPHYR_BASE}/cmake/compiler/clang/target_arm.cmake)
  elseif("${ARCH}" STREQUAL "arm64")
    include(${ZEPHYR_BASE}/cmake/compiler/clang/target_arm64.cmake)
  elseif("${ARCH}" STREQUAL "riscv")
    include(${ZEPHYR_BASE}/cmake/compiler/gcc/target_riscv.cmake)
  endif()

  if(DEFINED CMAKE_C_COMPILER_TARGET)
    set(clang_target_flag "--target=${CMAKE_C_COMPILER_TARGET}")
  endif()

  foreach(file_name include/stddef.h)
    execute_process(
      COMMAND ${CMAKE_C_COMPILER} --print-file-name=${file_name}
      OUTPUT_VARIABLE _OUTPUT
      )
    get_filename_component(_OUTPUT "${_OUTPUT}" DIRECTORY)
    string(REGEX REPLACE "\n" "" _OUTPUT ${_OUTPUT})

    list(APPEND NOSTDINC ${_OUTPUT})
  endforeach()

  foreach(isystem_include_dir ${NOSTDINC})
    list(APPEND isystem_include_flags -isystem "\"${isystem_include_dir}\"")
  endforeach()

  if(CONFIG_X86)
    if(CONFIG_64BIT)
      list(APPEND TOOLCHAIN_C_FLAGS "-m64")
    else()
      list(APPEND TOOLCHAIN_C_FLAGS "-m32")
    endif()
  endif()

  # LLVM will use a default sysroot for selection of the C library. The default
  # C library sysroot was defined at built time of clang/LLVM.
  #
  # For example, LLVM for Arm comes pre-built with Picolibc, and thus no flags
  # are required for selecting Picolibc.
  #
  # Other clang/LLVM distributions may come with other pre-built C libraries.
  # clang/LLVM supports using an alternative C library, either by direct linking,
  # or by specifying '--sysroot <path>'.
  #
  # LLVM for Arm provides a 'newlib.cfg' file for newlib C selection.
  # Let us support this principle by looking for a dedicated 'newlib.cfg' or
  # 'picolibc.cfg' and specify '--config <spec>.cfg' if such a file is found.
  # If no cfg-file matching the chosen C implementation, then we assume that the
  # chosen C implementation is identical to the default C library used be the
  # toolchain.
  if(CONFIG_NEWLIB_LIBC)
    file(GLOB_RECURSE newlib_cfg ${LLVM_TOOLCHAIN_PATH}/newlib.cfg)
    if(newlib_cfg)
      list(GET newlib_cfg 0 newlib_cfg)
      set_linker_property(PROPERTY c_library "--config=${newlib_cfg};-lc")
      list(APPEND CMAKE_REQUIRED_FLAGS --config=${newlib_cfg})
      list(APPEND TOOLCHAIN_C_FLAGS --config=${newlib_cfg})
    endif()
  endif()

  if(CONFIG_PICOLIBC)
    file(GLOB_RECURSE picolibc_cfg ${LLVM_TOOLCHAIN_PATH}/picolibc.cfg)
    if(picolibc_cfg)
      list(GET picolibc_cfg 0 picolibc_cfg)
      set_linker_property(PROPERTY c_library "--config=${picolibc_cfg};-lc")
      list(APPEND CMAKE_REQUIRED_FLAGS --config=${picolibc_cfg})
      list(APPEND TOOLCHAIN_C_FLAGS --config=${picolibc_cfg})
    endif()
  endif()

  # This libgcc code is partially duplicated in compiler/*/target.cmake
  execute_process(
    COMMAND ${CMAKE_C_COMPILER} ${clang_target_flag} ${TOOLCHAIN_C_FLAGS}
            --print-libgcc-file-name
    OUTPUT_VARIABLE RTLIB_FILE_NAME
    OUTPUT_STRIP_TRAILING_WHITESPACE
    )

  get_filename_component(RTLIB_DIR ${RTLIB_FILE_NAME} DIRECTORY)
  get_filename_component(RTLIB_NAME_WITH_PREFIX ${RTLIB_FILE_NAME} NAME_WLE)
  string(REPLACE lib "" RTLIB_NAME ${RTLIB_NAME_WITH_PREFIX})

  set_property(TARGET linker PROPERTY lib_include_dir "-L${RTLIB_DIR}")
  set_property(TARGET linker PROPERTY rt_library "-l${RTLIB_NAME}")

  list(APPEND CMAKE_REQUIRED_FLAGS -nostartfiles -nostdlib ${isystem_include_flags})
  string(REPLACE ";" " " CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")

endif()