cmake/modules/LLVMLibCLibraryRules.cmake

# A rule to build a library from a collection of entrypoint objects.
# Usage:
#     add_entrypoint_library(
#       DEPENDS <list of add_entrypoint_object targets>
#     )
function(add_entrypoint_library target_name)
  cmake_parse_arguments(
    "ENTRYPOINT_LIBRARY"
    "" # No optional arguments
    "" # No single value arguments
    "DEPENDS" # Multi-value arguments
    ${ARGN}
  )
  if(NOT ENTRYPOINT_LIBRARY_DEPENDS)
    message(FATAL_ERROR "'add_entrypoint_library' target requires a DEPENDS list "
                        "of 'add_entrypoint_object' targets.")
  endif()

  set(obj_list "")
  foreach(dep IN LISTS ENTRYPOINT_LIBRARY_DEPENDS)
    get_target_property(dep_type ${dep} "TARGET_TYPE")
    if(NOT (${dep_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE}))
      message(FATAL_ERROR "Dependency '${dep}' of 'add_entrypoint_collection' is "
                          "not an 'add_entrypoint_object' target.")
    endif()
    get_target_property(target_obj_files ${dep} "OBJECT_FILES")
    list(APPEND obj_list "${target_obj_files}")
  endforeach(dep)
  list(REMOVE_DUPLICATES obj_list)

  set(library_file "${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}${target_name}${CMAKE_STATIC_LIBRARY_SUFFIX}")
  add_custom_command(
    OUTPUT ${library_file}
    COMMAND ${CMAKE_AR} -r ${library_file} ${obj_list}
    DEPENDS ${obj_list}
  )
  add_custom_target(
    ${target_name}
    ALL
    DEPENDS ${library_file}
  )
endfunction(add_entrypoint_library)

# Rule to build a shared library of redirector objects.
function(add_redirector_library target_name)
  cmake_parse_arguments(
    "REDIRECTOR_LIBRARY"
    ""
    ""
    "DEPENDS"
    ${ARGN}
  )

  set(obj_files "")
  foreach(dep IN LISTS REDIRECTOR_LIBRARY_DEPENDS)
    # TODO: Ensure that each dep is actually a add_redirector_object target.
    list(APPEND obj_files $<TARGET_OBJECTS:${dep}>)
  endforeach(dep)

  # TODO: Call the linker explicitly instead of calling the compiler driver to
  # prevent DT_NEEDED on C++ runtime.
  add_library(
    ${target_name}
    SHARED
    ${obj_files}
  )
  set_target_properties(${target_name} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})

  target_link_libraries(
    ${target_name}
    -nostdlib -lc -lm
  )

  set_target_properties(
    ${target_name}
    PROPERTIES
      LINKER_LANGUAGE "C"
  )
endfunction(add_redirector_library)

# Rule to add header only libraries.
# Usage
#    add_header_library(
#      <target name>
#      HDRS  <list of .h files part of the library>
#      DEPENDS <list of dependencies>
#    )
function(add_header_library target_name)
  cmake_parse_arguments(
    "ADD_HEADER"
    "" # No optional arguments
    "" # No Single value arguments
    "HDRS;DEPENDS" # Multi-value arguments
    ${ARGN}
  )

  if(NOT ADD_HEADER_HDRS)
    message(FATAL_ERROR "'add_header_library' target requires a HDRS list of .h files.")
  endif()

  get_fq_target_name(${target_name} fq_target_name)

  set(FULL_HDR_PATHS "")
  # TODO: Remove this foreach block when we can switch to the new
  # version of the CMake policy CMP0076.
  foreach(hdr IN LISTS ADD_HEADER_HDRS)
    list(APPEND FULL_HDR_PATHS ${CMAKE_CURRENT_SOURCE_DIR}/${hdr})
  endforeach()

  set(interface_target_name "${fq_target_name}_header_library__")

  add_library(${interface_target_name} INTERFACE)
  target_sources(${interface_target_name} INTERFACE ${FULL_HDR_PATHS})
  if(ADD_HEADER_DEPENDS)
    get_fq_deps_list(fq_deps_list ${ADD_HEADER_DEPENDS})
    add_dependencies(${interface_target_name} ${fq_deps_list})
  endif()

  add_custom_target(${fq_target_name})
  add_dependencies(${fq_target_name} ${interface_target_name})
  set_target_properties(
    ${fq_target_name}
    PROPERTIES
      "TARGET_TYPE" "HDR_LIBRARY"
  )
endfunction(add_header_library)