[libc] [NFC] Split the CMake rules into multiple files.

[sivachandra]

Summary

The single file was getting too long to be convenient to navigate. This
patch splits it up two into 4 files one each for header rules,
object rules, library rules, and test rules.

libc/cmake/modules/LLVMLibCHeaderRules.cmake

+# A rule for self contained header file targets.
+# This rule merely copies the header file from the current source directory to
+# the current binary directory.
+# Usage:
+#     add_header(
+#       <target name>
+#       HDR <header file>
+#     )
+function(add_header target_name)
+  cmake_parse_arguments(
+    "ADD_HEADER"
+    ""    # No optional arguments
+    "HDR" # Single value arguments
+    "DEPENDS"
+    ${ARGN}
+  )
+  if(NOT ADD_HEADER_HDR)
+    message(FATAL_ERROR "'add_header' rules requires the HDR argument specifying a headef file.")
+  endif()
+
+  set(dest_file ${CMAKE_CURRENT_BINARY_DIR}/${ADD_HEADER_HDR})
+  set(src_file ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_HEADER_HDR})
+
+  add_custom_command(
+    OUTPUT ${dest_file}
+    COMMAND cp ${src_file} ${dest_file}
+    DEPENDS ${src_file}
+  )
+
+  get_fq_target_name(${target_name} fq_target_name)
+  add_custom_target(
+    ${fq_target_name}
+    DEPENDS ${dest_file}
+  )
+
+  if(ADD_HEADER_DEPENDS)
+    get_fq_deps_list(fq_deps_list ${ADD_HEADER_DEPENDS})
+    add_dependencies(
+      ${fq_target_name} ${fq_deps_list}
+    )
+  endif()
+endfunction(add_header)
+
+# A rule for generated header file targets.
+# Usage:
+#     add_gen_header(
+#       <target name>
+#       DEF_FILE <.h.def file>
+#       GEN_HDR <generated header file name>
+#       PARAMS <list of name=value pairs>
+#       DATA_FILES <list input data files>
+#     )
+function(add_gen_header target_name)
+  cmake_parse_arguments(
+    "ADD_GEN_HDR"
+    "" # No optional arguments
+    "DEF_FILE;GEN_HDR" # Single value arguments
+    "PARAMS;DATA_FILES;DEPENDS"     # Multi value arguments
+    ${ARGN}
+  )
+  if(NOT ADD_GEN_HDR_DEF_FILE)
+    message(FATAL_ERROR "`add_gen_hdr` rule requires DEF_FILE to be specified.")
+  endif()
+  if(NOT ADD_GEN_HDR_GEN_HDR)
+    message(FATAL_ERROR "`add_gen_hdr` rule requires GEN_HDR to be specified.")
+  endif()
+
+  set(out_file ${CMAKE_CURRENT_BINARY_DIR}/${ADD_GEN_HDR_GEN_HDR})
+  set(in_file ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_GEN_HDR_DEF_FILE})
+
+  set(fq_data_files "")
+  if(ADD_GEN_HDR_DATA_FILES)
+    foreach(data_file IN LISTS ADD_GEN_HDR_DATA_FILES)
+      list(APPEND fq_data_files "${CMAKE_CURRENT_SOURCE_DIR}/${data_file}")
+    endforeach(data_file)
+  endif()
+
+  set(replacement_params "")
+  if(ADD_GEN_HDR_PARAMS)
+    list(APPEND replacement_params "--args" ${ADD_GEN_HDR_PARAMS})
+  endif()
+
+  set(gen_hdr_script "${LIBC_BUILD_SCRIPTS_DIR}/gen_hdr.py")
+
+  file(GLOB td_includes ${LIBC_SOURCE_DIR}/spec/*.td)
+
+  add_custom_command(
+    OUTPUT ${out_file}
+    COMMAND $<TARGET_FILE:libc-hdrgen> -o ${out_file} --header ${ADD_GEN_HDR_GEN_HDR}
+            --def ${in_file} ${replacement_params} -I ${LIBC_SOURCE_DIR}
+            ${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/api.td
+
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    DEPENDS ${in_file} ${fq_data_files} ${td_includes} 
+            ${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/api.td libc-hdrgen
+  )
+
+  get_fq_target_name(${target_name} fq_target_name)
+  if(ADD_GEN_HDR_DEPENDS)
+    get_fq_deps_list(fq_deps_list ${ADD_GEN_HDR_DEPENDS})
+  endif()
+  add_custom_target(
+    ${fq_target_name}
+    DEPENDS ${out_file} ${fq_deps_list}
+  )
+endfunction(add_gen_header)

libc/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)

libc/cmake/modules/LLVMLibCObjectRules.cmake

+set(OBJECT_LIBRARY_TARGET_TYPE "OBJECT_LIBRARY")
+
+# Rule which is essentially a wrapper over add_library to compile a set of
+# sources to object files.
+# Usage:
+#     add_object_library(
+#       <target_name>
+#       HDRS <list of header files>
+#       SRCS <list of source files>
+#       DEPENDS <list of dependencies>
+#       COMPILE_OPTIONS <optional list of special compile options for this target>
+function(add_object_library target_name)
+  cmake_parse_arguments(
+    "ADD_OBJECT"
+    "" # No option arguments
+    "" # Single value arguments
+    "SRCS;HDRS;COMPILE_OPTIONS;DEPENDS" # Multivalue arguments
+    ${ARGN}
+  )
+
+  if(NOT ADD_OBJECT_SRCS)
+    message(FATAL_ERROR "'add_object_library' rule requires SRCS to be specified.")
+  endif()
+
+  get_fq_target_name(${target_name} fq_target_name)
+  add_library(
+    ${fq_target_name}
+    OBJECT
+    ${ADD_OBJECT_SRCS}
+    ${ADD_OBJECT_HDRS}
+  )
+  target_include_directories(
+    ${fq_target_name}
+    PRIVATE
+      ${LIBC_BUILD_DIR}/include
+      ${LIBC_SOURCE_DIR}
+      ${LIBC_BUILD_DIR}
+  )
+  if(ADD_OBJECT_COMPILE_OPTIONS)
+    target_compile_options(
+      ${fq_target_name}
+      PRIVATE ${ADD_OBJECT_COMPILE_OPTIONS}
+    )
+  endif()
+
+  set(all_object_files $<TARGET_OBJECTS:${fq_target_name}>)
+  if(ADD_OBJECT_DEPENDS)
+    get_fq_deps_list(fq_deps_list ${ADD_OBJECT_DEPENDS})
+    add_dependencies(
+      ${fq_target_name}
+      ${fq_deps_list}
+    )
+    foreach(obj_target IN LISTS fq_deps_list)
+      if(NOT TARGET obj_target)
+        # Not all targets will be visible. So, we will ignore those which aren't
+        # visible yet.
+        continue()
+      endif()
+      get_target_property(obj_type ${obj_target} "TARGET_TYPE")
+      if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})))
+        continue()
+      endif()
+      # If a dependency is also a object file library, we will collect the list of
+      # object files from it.
+      get_target_property(obj_files ${obj_target} "OBJECT_FILES")
+      list(APPEND all_object_files ${obj_files})
+    endforeach(obj_target)
+  endif()
+  list(REMOVE_DUPLICATES all_object_files)
+
+  set_target_properties(
+    ${fq_target_name}
+    PROPERTIES
+      "TARGET_TYPE" ${OBJECT_LIBRARY_TARGET_TYPE}
+      "OBJECT_FILES" "${all_object_files}"
+  )
+endfunction(add_object_library)
+
+set(ENTRYPOINT_OBJ_TARGET_TYPE "ENTRYPOINT_OBJ")
+
+# A rule for entrypoint object targets.
+# Usage:
+#     add_entrypoint_object(
+#       <target_name>
+#       [ALIAS|REDIRECTED] # Specified if the entrypoint is redirected or an alias.
+#       [NAME] <the C name of the entrypoint if different from target_name>
+#       SRCS <list of .cpp files>
+#       HDRS <list of .h files>
+#       DEPENDS <list of dependencies>
+#       COMPILE_OPTIONS <optional list of special compile options for this target>
+#       SPECIAL_OBJECTS <optional list of special object targets added by the rule `add_object`>
+#     )
+function(add_entrypoint_object target_name)
+  cmake_parse_arguments(
+    "ADD_ENTRYPOINT_OBJ"
+    "ALIAS;REDIRECTED" # Optional argument
+    "NAME" # Single value arguments
+    "SRCS;HDRS;DEPENDS;COMPILE_OPTIONS"  # Multi value arguments
+    ${ARGN}
+  )
+
+  get_fq_target_name(${target_name} fq_target_name)
+
+  if(ADD_ENTRYPOINT_OBJ_ALIAS)
+    # Alias targets help one add aliases to other entrypoint object targets.
+    # One can use alias targets setup OS/machine independent entrypoint targets.
+    list(LENGTH ADD_ENTRYPOINT_OBJ_DEPENDS deps_size)
+    if(NOT (${deps_size} EQUAL "1"))
+      message(FATAL_ERROR "An entrypoint alias should have exactly one dependency.")
+    endif()
+    list(GET ADD_ENTRYPOINT_OBJ_DEPENDS 0 dep_target)
+    get_fq_dep_name(fq_dep_name ${dep_target})
+    if(NOT TARGET ${fq_dep_name})
+      message(WARNING "Aliasee ${fq_dep_name} for entrypoint alias ${target_name} missing; "
+                      "Target ${target_name} will be ignored.")
+      return()
+    endif()
+
+    get_target_property(obj_type ${fq_dep_name} "TARGET_TYPE")
+    if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE})))
+      message(FATAL_ERROR "The aliasee of an entrypoint alias should be an entrypoint.")
+    endif()
+
+    add_custom_target(${fq_target_name})
+    add_dependencies(${fq_target_name} ${fq_dep_name})
+    get_target_property(all_objects ${fq_dep_name} "OBJECT_FILES")
+    get_target_property(all_objects_raw ${fq_dep_name} "OBJECT_FILES_RAW")
+    set_target_properties(
+      ${fq_target_name}
+      PROPERTIES
+        "TARGET_TYPE" ${ENTRYPOINT_OBJ_TARGET_TYPE}
+        "OBJECT_FILES" "${all_objects}"
+        "OBJECT_FILES_RAW" "${all_objects_raw}"
+    )
+    return()
+  endif()
+
+  if(NOT ADD_ENTRYPOINT_OBJ_SRCS)
+    message(FATAL_ERROR "`add_entrypoint_object` rule requires SRCS to be specified.")
+  endif()
+  if(NOT ADD_ENTRYPOINT_OBJ_HDRS)
+    message(FATAL_ERROR "`add_entrypoint_object` rule requires HDRS to be specified.")
+  endif()
+
+  set(entrypoint_name ${target_name})
+  if(ADD_ENTRYPOINT_OBJ_NAME)
+    set(entrypoint_name ${ADD_ENTRYPOINT_OBJ_NAME})
+  endif()
+
+  set(objects_target_name "${fq_target_name}_objects")
+
+  add_library(
+    ${objects_target_name}
+    # We want an object library as the objects will eventually get packaged into
+    # an archive (like libc.a).
+    OBJECT
+    ${ADD_ENTRYPOINT_OBJ_SRCS}
+    ${ADD_ENTRYPOINT_OBJ_HDRS}
+  )
+  target_compile_options(
+    ${objects_target_name}
+    BEFORE
+    PRIVATE
+      -fpie ${LLVM_CXX_STD_default}
+  )
+  target_include_directories(
+    ${objects_target_name}
+    PRIVATE
+      ${LIBC_BUILD_DIR}/include
+      ${LIBC_SOURCE_DIR}
+      ${LIBC_BUILD_DIR}
+  )
+  add_dependencies(
+    ${objects_target_name}
+    libc.src.__support.common
+  )
+  set(dep_objects "")
+  if(ADD_ENTRYPOINT_OBJ_DEPENDS)
+    get_fq_deps_list(fq_deps_list ${ADD_ENTRYPOINT_OBJ_DEPENDS})
+    add_dependencies(
+      ${objects_target_name}
+      ${fq_deps_list}
+    )
+    foreach(dep_target IN LISTS fq_deps_list)
+      if(NOT TARGET ${dep_target})
+        # Not all targets will be visible. So, we will ignore those which aren't
+        # visible yet.
+        continue()
+      endif()
+      get_target_property(obj_type ${dep_target} "TARGET_TYPE")
+      if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})))
+        # Even from among the visible targets, we will collect object files
+        # only from add_object_library targets.
+        continue()
+      endif()
+      # Calling get_target_property requires that the target be visible at this
+      # point. For object library dependencies, this is a reasonable requirement.
+      # We can revisit this in future if we need cases which break under this
+      # requirement.
+      get_target_property(obj_files ${dep_target} "OBJECT_FILES")
+      list(APPEND dep_objects ${obj_files})
+    endforeach(dep_target)
+  endif()
+  list(REMOVE_DUPLICATES dep_objects)
+
+  if(ADD_ENTRYPOINT_OBJ_COMPILE_OPTIONS)
+    target_compile_options(
+      ${objects_target_name}
+      PRIVATE ${ADD_ENTRYPOINT_OBJ_COMPILE_OPTIONS}
+    )
+  endif()
+
+  set(object_file_raw "${CMAKE_CURRENT_BINARY_DIR}/${target_name}_raw.o")
+  set(object_file "${CMAKE_CURRENT_BINARY_DIR}/${target_name}.o")
+
+  set(input_objects $<TARGET_OBJECTS:${objects_target_name}>)
+  add_custom_command(
+    OUTPUT ${object_file_raw}
+    DEPENDS ${input_objects}
+    COMMAND ${CMAKE_LINKER} -r ${input_objects} -o ${object_file_raw}
+  )
+
+  set(alias_attributes "0,function,global")
+  if(ADD_ENTRYPOINT_OBJ_REDIRECTED)
+    set(alias_attributes "${alias_attributes},hidden")
+  endif()
+
+  add_custom_command(
+    OUTPUT ${object_file}
+    # We llvm-objcopy here as GNU-binutils objcopy does not support the 'hidden' flag.
+    DEPENDS ${object_file_raw} ${llvm-objcopy}
+    COMMAND $<TARGET_FILE:llvm-objcopy> --add-symbol
+            "${entrypoint_name}=.llvm.libc.entrypoint.${entrypoint_name}:${alias_attributes}"
+            ${object_file_raw} ${object_file}
+  )
+
+  add_custom_target(
+    ${fq_target_name}
+    ALL
+    DEPENDS ${object_file}
+  )
+  set(all_objects ${object_file})
+  list(APPEND all_objects ${dep_objects})
+  set(all_objects_raw ${object_file_raw})
+  list(APPEND all_objects_raw ${dep_objects})
+  set_target_properties(
+    ${fq_target_name}
+    PROPERTIES
+      "TARGET_TYPE" ${ENTRYPOINT_OBJ_TARGET_TYPE}
+      "OBJECT_FILES" "${all_objects}"
+      "OBJECT_FILES_RAW" "${all_objects_raw}"
+  )
+
+  if(LLVM_LIBC_ENABLE_LINTING)
+    set(lint_timestamp "${CMAKE_CURRENT_BINARY_DIR}/.${target_name}.__lint_timestamp__")
+
+    add_custom_command(
+      OUTPUT ${lint_timestamp}
+      # --quiet is used to surpress warning statistics from clang-tidy like:
+      #     Suppressed X warnings (X in non-user code).
+      # There seems to be a bug in clang-tidy where by even with --quiet some
+      # messages from clang's own diagnostics engine leak through:
+      #     X warnings generated.
+      # Until this is fixed upstream, we use -fno-caret-diagnostics to surpress
+      # these.
+      COMMAND $<TARGET_FILE:clang-tidy> "--extra-arg=-fno-caret-diagnostics" --quiet
+              # Path to directory containing compile_commands.json
+              -p ${PROJECT_BINARY_DIR}
+              ${ADD_ENTRYPOINT_OBJ_SRCS}
+      # We have two options for running commands, add_custom_command and
+      # add_custom_target. We don't want to run the linter unless source files
+      # have changed. add_custom_target explicitly runs everytime therefore we
+      # use add_custom_command. This function requires an output file and since
+      # linting doesn't produce a file, we create a dummy file using a
+      # crossplatform touch.
+      COMMAND "${CMAKE_COMMAND}" -E touch ${lint_timestamp}
+      COMMENT "Linting... ${target_name}"
+      DEPENDS ${clang-tidy} ${objects_target_name} ${ADD_ENTRYPOINT_OBJ_SRCS}
+      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    )
+
+    add_custom_target(${fq_target_name}.__lint__
+      DEPENDS ${lint_timestamp})
+    add_dependencies(lint-libc ${fq_target_name}.__lint__)
+    add_dependencies(${fq_target_name} ${fq_target_name}.__lint__)
+  endif()
+
+endfunction(add_entrypoint_object)
+
+# Rule build a redirector object file.
+function(add_redirector_object target_name)
+  cmake_parse_arguments(
+    "REDIRECTOR_OBJECT"
+    "" # No optional arguments
+    "SRC" # The cpp file in which the redirector is defined.
+    "" # No multivalue arguments
+    ${ARGN}
+  )
+  if(NOT REDIRECTOR_OBJECT_SRC)
+    message(FATAL_ERROR "'add_redirector_object' rule requires SRC option listing one source file.")
+  endif()
+
+  add_library(
+    ${target_name}
+    OBJECT
+    ${REDIRECTOR_OBJECT_SRC}
+  )
+  target_compile_options(
+    ${target_name}
+    BEFORE PRIVATE -fPIC
+  )
+endfunction(add_redirector_object)
+

libc/cmake/modules/LLVMLibCRules.cmake

 include(LLVMLibCTargetNameUtils)
-
-# A rule for self contained header file targets.
-# This rule merely copies the header file from the current source directory to
-# the current binary directory.
-# Usage:
-#     add_header(
-#       <target name>
-#       HDR <header file>
-#     )
-function(add_header target_name)
-  cmake_parse_arguments(
-    "ADD_HEADER"
-    ""    # No optional arguments
-    "HDR" # Single value arguments
-    "DEPENDS"
-    ${ARGN}
-  )
-  if(NOT ADD_HEADER_HDR)
-    message(FATAL_ERROR "'add_header' rules requires the HDR argument specifying a headef file.")
-  endif()
-
-  set(dest_file ${CMAKE_CURRENT_BINARY_DIR}/${ADD_HEADER_HDR})
-  set(src_file ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_HEADER_HDR})
-
-  add_custom_command(
-    OUTPUT ${dest_file}
-    COMMAND cp ${src_file} ${dest_file}
-    DEPENDS ${src_file}
-  )
-
-  get_fq_target_name(${target_name} fq_target_name)
-  add_custom_target(
-    ${fq_target_name}
-    DEPENDS ${dest_file}
-  )
-
-  if(ADD_HEADER_DEPENDS)
-    get_fq_deps_list(fq_deps_list ${ADD_HEADER_DEPENDS})
-    add_dependencies(
-      ${fq_target_name} ${fq_deps_list}
-    )
-  endif()
-endfunction(add_header)
-
-# A rule for generated header file targets.
-# Usage:
-#     add_gen_header(
-#       <target name>
-#       DEF_FILE <.h.def file>
-#       GEN_HDR <generated header file name>
-#       PARAMS <list of name=value pairs>
-#       DATA_FILES <list input data files>
-#     )
-function(add_gen_header target_name)
-  cmake_parse_arguments(
-    "ADD_GEN_HDR"
-    "" # No optional arguments
-    "DEF_FILE;GEN_HDR" # Single value arguments
-    "PARAMS;DATA_FILES;DEPENDS"     # Multi value arguments
-    ${ARGN}
-  )
-  if(NOT ADD_GEN_HDR_DEF_FILE)
-    message(FATAL_ERROR "`add_gen_hdr` rule requires DEF_FILE to be specified.")
-  endif()
-  if(NOT ADD_GEN_HDR_GEN_HDR)
-    message(FATAL_ERROR "`add_gen_hdr` rule requires GEN_HDR to be specified.")
-  endif()
-
-  set(out_file ${CMAKE_CURRENT_BINARY_DIR}/${ADD_GEN_HDR_GEN_HDR})
-  set(in_file ${CMAKE_CURRENT_SOURCE_DIR}/${ADD_GEN_HDR_DEF_FILE})
-
-  set(fq_data_files "")
-  if(ADD_GEN_HDR_DATA_FILES)
-    foreach(data_file IN LISTS ADD_GEN_HDR_DATA_FILES)
-      list(APPEND fq_data_files "${CMAKE_CURRENT_SOURCE_DIR}/${data_file}")
-    endforeach(data_file)
-  endif()
-
-  set(replacement_params "")
-  if(ADD_GEN_HDR_PARAMS)
-    list(APPEND replacement_params "--args" ${ADD_GEN_HDR_PARAMS})
-  endif()
-
-  set(gen_hdr_script "${LIBC_BUILD_SCRIPTS_DIR}/gen_hdr.py")
-
-  file(GLOB td_includes ${LIBC_SOURCE_DIR}/spec/*.td)
-
-  add_custom_command(
-    OUTPUT ${out_file}
-    COMMAND $<TARGET_FILE:libc-hdrgen> -o ${out_file} --header ${ADD_GEN_HDR_GEN_HDR}
-            --def ${in_file} ${replacement_params} -I ${LIBC_SOURCE_DIR}
-            ${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/api.td
-
-    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-    DEPENDS ${in_file} ${fq_data_files} ${td_includes} 
-            ${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/api.td libc-hdrgen
-  )
-
-  get_fq_target_name(${target_name} fq_target_name)
-  if(ADD_GEN_HDR_DEPENDS)
-    get_fq_deps_list(fq_deps_list ${ADD_GEN_HDR_DEPENDS})
-  endif()
-  add_custom_target(
-    ${fq_target_name}
-    DEPENDS ${out_file} ${fq_deps_list}
-  )
-endfunction(add_gen_header)
-
-set(OBJECT_LIBRARY_TARGET_TYPE "OBJECT_LIBRARY")
-
-# Rule which is essentially a wrapper over add_library to compile a set of
-# sources to object files.
-# Usage:
-#     add_object_library(
-#       <target_name>
-#       HDRS <list of header files>
-#       SRCS <list of source files>
-#       DEPENDS <list of dependencies>
-#       COMPILE_OPTIONS <optional list of special compile options for this target>
-function(add_object_library target_name)
-  cmake_parse_arguments(
-    "ADD_OBJECT"
-    "" # No option arguments
-    "" # Single value arguments
-    "SRCS;HDRS;COMPILE_OPTIONS;DEPENDS" # Multivalue arguments
-    ${ARGN}
-  )
-
-  if(NOT ADD_OBJECT_SRCS)
-    message(FATAL_ERROR "'add_object_library' rule requires SRCS to be specified.")
-  endif()
-
-  get_fq_target_name(${target_name} fq_target_name)
-  add_library(
-    ${fq_target_name}
-    OBJECT
-    ${ADD_OBJECT_SRCS}
-    ${ADD_OBJECT_HDRS}
-  )
-  target_include_directories(
-    ${fq_target_name}
-    PRIVATE
-      "${LIBC_BUILD_DIR}/include;${LIBC_SOURCE_DIR};${LIBC_BUILD_DIR}"
-  )
-  if(ADD_OBJECT_COMPILE_OPTIONS)
-    target_compile_options(
-      ${fq_target_name}
-      PRIVATE ${ADD_OBJECT_COMPILE_OPTIONS}
-    )
-  endif()
-
-  set(all_object_files $<TARGET_OBJECTS:${fq_target_name}>)
-  if(ADD_OBJECT_DEPENDS)
-    get_fq_deps_list(fq_deps_list ${ADD_OBJECT_DEPENDS})
-    add_dependencies(
-      ${fq_target_name}
-      ${fq_deps_list}
-    )
-    foreach(obj_target IN LISTS fq_deps_list)
-      if(NOT TARGET obj_target)
-        # Not all targets will be visible. So, we will ignore those which aren't
-        # visible yet.
-        continue()
-      endif()
-      get_target_property(obj_type ${obj_target} "TARGET_TYPE")
-      if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})))
-        continue()
-      endif()
-      # If a dependency is also a object file library, we will collect the list of
-      # object files from it.
-      get_target_property(obj_files ${obj_target} "OBJECT_FILES")
-      list(APPEND all_object_files ${obj_files})
-    endforeach(obj_target)
-  endif()
-  list(REMOVE_DUPLICATES all_object_files)
-
-  set_target_properties(
-    ${fq_target_name}
-    PROPERTIES
-      "TARGET_TYPE" ${OBJECT_LIBRARY_TARGET_TYPE}
-      "OBJECT_FILES" "${all_object_files}"
-  )
-endfunction(add_object_library)
-
-set(ENTRYPOINT_OBJ_TARGET_TYPE "ENTRYPOINT_OBJ")
-
-# A rule for entrypoint object targets.
-# Usage:
-#     add_entrypoint_object(
-#       <target_name>
-#       [ALIAS|REDIRECTED] # Specified if the entrypoint is redirected or an alias.
-#       [NAME] <the C name of the entrypoint if different from target_name>
-#       SRCS <list of .cpp files>
-#       HDRS <list of .h files>
-#       DEPENDS <list of dependencies>
-#       COMPILE_OPTIONS <optional list of special compile options for this target>
-#       SPECIAL_OBJECTS <optional list of special object targets added by the rule `add_object`>
-#     )
-function(add_entrypoint_object target_name)
-  cmake_parse_arguments(
-    "ADD_ENTRYPOINT_OBJ"
-    "ALIAS;REDIRECTED" # Optional argument
-    "NAME" # Single value arguments
-    "SRCS;HDRS;DEPENDS;COMPILE_OPTIONS"  # Multi value arguments
-    ${ARGN}
-  )
-
-  get_fq_target_name(${target_name} fq_target_name)
-
-  if(ADD_ENTRYPOINT_OBJ_ALIAS)
-    # Alias targets help one add aliases to other entrypoint object targets.
-    # One can use alias targets setup OS/machine independent entrypoint targets.
-    list(LENGTH ADD_ENTRYPOINT_OBJ_DEPENDS deps_size)
-    if(NOT (${deps_size} EQUAL "1"))
-      message(FATAL_ERROR "An entrypoint alias should have exactly one dependency.")
-    endif()
-    list(GET ADD_ENTRYPOINT_OBJ_DEPENDS 0 dep_target)
-    get_fq_dep_name(fq_dep_name ${dep_target})
-    if(NOT TARGET ${fq_dep_name})
-      message(WARNING "Aliasee ${fq_dep_name} for entrypoint alias ${target_name} missing; "
-                      "Target ${target_name} will be ignored.")
-      return()
-    endif()
-
-    get_target_property(obj_type ${fq_dep_name} "TARGET_TYPE")
-    if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE})))
-      message(FATAL_ERROR "The aliasee of an entrypoint alias should be an entrypoint.")
-    endif()
-
-    add_custom_target(${fq_target_name})
-    add_dependencies(${fq_target_name} ${fq_dep_name})
-    get_target_property(all_objects ${fq_dep_name} "OBJECT_FILES")
-    get_target_property(all_objects_raw ${fq_dep_name} "OBJECT_FILES_RAW")
-    set_target_properties(
-      ${fq_target_name}
-      PROPERTIES
-        "TARGET_TYPE" ${ENTRYPOINT_OBJ_TARGET_TYPE}
-        "OBJECT_FILES" "${all_objects}"
-        "OBJECT_FILES_RAW" "${all_objects_raw}"
-    )
-    return()
-  endif()
-
-  if(NOT ADD_ENTRYPOINT_OBJ_SRCS)
-    message(FATAL_ERROR "`add_entrypoint_object` rule requires SRCS to be specified.")
-  endif()
-  if(NOT ADD_ENTRYPOINT_OBJ_HDRS)
-    message(FATAL_ERROR "`add_entrypoint_object` rule requires HDRS to be specified.")
-  endif()
-
-  set(entrypoint_name ${target_name})
-  if(ADD_ENTRYPOINT_OBJ_NAME)
-    set(entrypoint_name ${ADD_ENTRYPOINT_OBJ_NAME})
-  endif()
-
-  set(objects_target_name "${fq_target_name}_objects")
-
-  add_library(
-    ${objects_target_name}
-    # We want an object library as the objects will eventually get packaged into
-    # an archive (like libc.a).
-    OBJECT
-    ${ADD_ENTRYPOINT_OBJ_SRCS}
-    ${ADD_ENTRYPOINT_OBJ_HDRS}
-  )
-  target_compile_options(
-    ${objects_target_name}
-    BEFORE
-    PRIVATE
-      -fpie ${LLVM_CXX_STD_default}
-  )
-  target_include_directories(
-    ${objects_target_name}
-    PRIVATE
-      "${LIBC_BUILD_DIR}/include;${LIBC_SOURCE_DIR};${LIBC_BUILD_DIR}"
-  )
-  add_dependencies(
-    ${objects_target_name}
-    libc.src.__support.common
-  )
-  set(dep_objects "")
-  if(ADD_ENTRYPOINT_OBJ_DEPENDS)
-    get_fq_deps_list(fq_deps_list ${ADD_ENTRYPOINT_OBJ_DEPENDS})
-    add_dependencies(
-      ${objects_target_name}
-      ${fq_deps_list}
-    )
-    foreach(dep_target IN LISTS fq_deps_list)
-      if(NOT TARGET ${dep_target})
-        # Not all targets will be visible. So, we will ignore those which aren't
-        # visible yet.
-        continue()
-      endif()
-      get_target_property(obj_type ${dep_target} "TARGET_TYPE")
-      if((NOT obj_type) OR (NOT (${obj_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})))
-        # Even from among the visible targets, we will collect object files
-        # only from add_object_library targets.
-        continue()
-      endif()
-      # Calling get_target_property requires that the target be visible at this
-      # point. For object library dependencies, this is a reasonable requirement.
-      # We can revisit this in future if we need cases which break under this
-      # requirement.
-      get_target_property(obj_files ${dep_target} "OBJECT_FILES")
-      list(APPEND dep_objects ${obj_files})
-    endforeach(dep_target)
-  endif()
-  list(REMOVE_DUPLICATES dep_objects)
-
-  if(ADD_ENTRYPOINT_OBJ_COMPILE_OPTIONS)
-    target_compile_options(
-      ${objects_target_name}
-      PRIVATE ${ADD_ENTRYPOINT_OBJ_COMPILE_OPTIONS}
-    )
-  endif()
-
-  set(object_file_raw "${CMAKE_CURRENT_BINARY_DIR}/${target_name}_raw.o")
-  set(object_file "${CMAKE_CURRENT_BINARY_DIR}/${target_name}.o")
-
-  set(input_objects $<TARGET_OBJECTS:${objects_target_name}>)
-  add_custom_command(
-    OUTPUT ${object_file_raw}
-    DEPENDS ${input_objects}
-    COMMAND ${CMAKE_LINKER} -r ${input_objects} -o ${object_file_raw}
-  )
-
-  set(alias_attributes "0,function,global")
-  if(ADD_ENTRYPOINT_OBJ_REDIRECTED)
-    set(alias_attributes "${alias_attributes},hidden")
-  endif()
-
-  add_custom_command(
-    OUTPUT ${object_file}
-    # We llvm-objcopy here as GNU-binutils objcopy does not support the 'hidden' flag.
-    DEPENDS ${object_file_raw} ${llvm-objcopy}
-    COMMAND $<TARGET_FILE:llvm-objcopy> --add-symbol "${entrypoint_name}=.llvm.libc.entrypoint.${entrypoint_name}:${alias_attributes}" ${object_file_raw} ${object_file}
-  )
-
-  add_custom_target(
-    ${fq_target_name}
-    ALL
-    DEPENDS ${object_file}
-  )
-  set(all_objects ${object_file})
-  list(APPEND all_objects ${dep_objects})
-  set(all_objects_raw ${object_file_raw})
-  list(APPEND all_objects_raw ${dep_objects})
-  set_target_properties(
-    ${fq_target_name}
-    PROPERTIES
-      "TARGET_TYPE" ${ENTRYPOINT_OBJ_TARGET_TYPE}
-      "OBJECT_FILES" "${all_objects}"
-      "OBJECT_FILES_RAW" "${all_objects_raw}"
-  )
-
-  if(LLVM_LIBC_ENABLE_LINTING)
-    set(lint_timestamp "${CMAKE_CURRENT_BINARY_DIR}/.${target_name}.__lint_timestamp__")
-
-    add_custom_command(
-      OUTPUT ${lint_timestamp}
-      # --quiet is used to surpress warning statistics from clang-tidy like:
-      #     Suppressed X warnings (X in non-user code).
-      # There seems to be a bug in clang-tidy where by even with --quiet some
-      # messages from clang's own diagnostics engine leak through:
-      #     X warnings generated.
-      # Until this is fixed upstream, we use -fno-caret-diagnostics to surpress
-      # these.
-      COMMAND $<TARGET_FILE:clang-tidy> "--extra-arg=-fno-caret-diagnostics" --quiet
-              # Path to directory containing compile_commands.json
-              -p ${PROJECT_BINARY_DIR}
-              ${ADD_ENTRYPOINT_OBJ_SRCS}
-      # We have two options for running commands, add_custom_command and
-      # add_custom_target. We don't want to run the linter unless source files
-      # have changed. add_custom_target explicitly runs everytime therefore we
-      # use add_custom_command. This function requires an output file and since
-      # linting doesn't produce a file, we create a dummy file using a
-      # crossplatform touch.
-      COMMAND "${CMAKE_COMMAND}" -E touch ${lint_timestamp}
-      COMMENT "Linting... ${target_name}"
-      DEPENDS ${clang-tidy} ${objects_target_name} ${ADD_ENTRYPOINT_OBJ_SRCS}
-      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-    )
-
-    add_custom_target(${fq_target_name}.__lint__
-      DEPENDS ${lint_timestamp})
-    add_dependencies(lint-libc ${fq_target_name}.__lint__)
-    add_dependencies(${fq_target_name} ${fq_target_name}.__lint__)
-  endif()
-
-endfunction(add_entrypoint_object)
-
-# 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 build a redirector object file.
-function(add_redirector_object target_name)
-  cmake_parse_arguments(
-    "REDIRECTOR_OBJECT"
-    "" # No optional arguments
-    "SRC" # The cpp file in which the redirector is defined.
-    "" # No multivalue arguments
-    ${ARGN}
-  )
-  if(NOT REDIRECTOR_OBJECT_SRC)
-    message(FATAL_ERROR "'add_redirector_object' rule requires SRC option listing one source file.")
-  endif()
-
-  add_library(
-    ${target_name}
-    OBJECT
-    ${REDIRECTOR_OBJECT_SRC}
-  )
-  target_compile_options(
-    ${target_name}
-    BEFORE PRIVATE -fPIC
-  )
-endfunction(add_redirector_object)
-
-# 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 a libc unittest.
-# Usage
-#    add_libc_unittest(
-#      <target name>
-#      SUITE <name of the suite this test belongs to>
-#      SRCS  <list of .cpp files for the test>
-#      HDRS  <list of .h files for the test>
-#      DEPENDS <list of dependencies>
-#      COMPILE_OPTIONS <list of special compile options for this target>
-#    )
-function(add_libc_unittest target_name)
-  if(NOT LLVM_INCLUDE_TESTS)
-    return()
-  endif()
-
-  cmake_parse_arguments(
-    "LIBC_UNITTEST"
-    "" # No optional arguments
-    "SUITE" # Single value arguments
-    "SRCS;HDRS;DEPENDS;COMPILE_OPTIONS" # Multi-value arguments
-    ${ARGN}
-  )
-  if(NOT LIBC_UNITTEST_SRCS)
-    message(FATAL_ERROR "'add_libc_unittest' target requires a SRCS list of .cpp files.")
-  endif()
-  if(NOT LIBC_UNITTEST_DEPENDS)
-    message(FATAL_ERROR "'add_libc_unittest' target requires a DEPENDS list of 'add_entrypoint_object' targets.")
-  endif()
-
-  set(library_deps "")
-  get_fq_deps_list(fq_deps_list ${LIBC_UNITTEST_DEPENDS})
-  foreach(dep IN LISTS fq_deps_list)
-    get_target_property(dep_type ${dep} "TARGET_TYPE")
-    if(${dep_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE})
-      get_target_property(obj_files ${dep} "OBJECT_FILES_RAW")
-      list(APPEND library_deps ${obj_files})
-    elseif(${dep_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})
-      get_target_property(obj_files ${dep} "OBJECT_FILES")
-      list(APPEND library_deps ${obj_files})
-    endif()
-    # TODO: Check if the dep is a normal CMake library target. If yes, then add it
-    # to the list of library_deps.
-  endforeach(dep)
-  list(REMOVE_DUPLICATES library_deps)
-
-  get_fq_target_name(${target_name} fq_target_name)
-  add_executable(
-    ${fq_target_name}
-    EXCLUDE_FROM_ALL
-    ${LIBC_UNITTEST_SRCS}
-    ${LIBC_UNITTEST_HDRS}
-  )
-  target_include_directories(
-    ${fq_target_name}
-    PRIVATE
-      ${LIBC_SOURCE_DIR}
-      ${LIBC_BUILD_DIR}
-      ${LIBC_BUILD_DIR}/include
-  )
-  if(LIBC_UNITTEST_COMPILE_OPTIONS)
-    target_compile_options(
-      ${target_name}
-      PRIVATE ${LIBC_UNITTEST_COMPILE_OPTIONS}
-    )
-  endif()
-
-  if(library_deps)
-    target_link_libraries(${fq_target_name} PRIVATE ${library_deps})
-  endif()
-
-  set_target_properties(${fq_target_name} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
-
-  add_dependencies(
-    ${fq_target_name}
-    ${fq_deps_list}
-  )
-
-  target_link_libraries(${fq_target_name} PRIVATE LibcUnitTest libc_test_utils)
-
-  add_custom_command(
-    TARGET ${fq_target_name}
-    POST_BUILD
-    COMMAND $<TARGET_FILE:${fq_target_name}>
-  )
-  if(LIBC_UNITTEST_SUITE)
-    add_dependencies(
-      ${LIBC_UNITTEST_SUITE}
-      ${fq_target_name}
-    )
-  endif()
-endfunction(add_libc_unittest)
-
-function(add_libc_testsuite suite_name)
-  add_custom_target(${suite_name})
-  add_dependencies(check-libc ${suite_name})
-endfunction(add_libc_testsuite)
-
-# Rule to add a fuzzer test.
-# Usage
-#    add_libc_fuzzer(
-#      <target name>
-#      SRCS  <list of .cpp files for the test>
-#      HDRS  <list of .h files for the test>
-#      DEPENDS <list of dependencies>
-#    )
-function(add_libc_fuzzer target_name)
-  cmake_parse_arguments(
-    "LIBC_FUZZER"
-    "" # No optional arguments
-    "" # Single value arguments
-    "SRCS;HDRS;DEPENDS" # Multi-value arguments
-    ${ARGN}
-  )
-  if(NOT LIBC_FUZZER_SRCS)
-    message(FATAL_ERROR "'add_libc_fuzzer' target requires a SRCS list of .cpp files.")
-  endif()
-  if(NOT LIBC_FUZZER_DEPENDS)
-    message(FATAL_ERROR "'add_libc_fuzzer' target requires a DEPENDS list of 'add_entrypoint_object' targets.")
-  endif()
-
-  get_fq_deps_list(fq_deps_list ${LIBC_FUZZER_DEPENDS})
-  set(library_deps "")
-  foreach(dep IN LISTS fq_deps_list)
-    get_target_property(dep_type ${dep} "TARGET_TYPE")
-    if (dep_type)
-      string(COMPARE EQUAL ${dep_type} ${ENTRYPOINT_OBJ_TARGET_TYPE} dep_is_entrypoint)
-      if(dep_is_entrypoint)
-        get_target_property(obj_file ${dep} "OBJECT_FILES_RAW")
-        list(APPEND library_deps ${obj_file})
-        continue()
-      endif()
-    endif()
-    # TODO: Check if the dep is a normal CMake library target. If yes, then add it
-    # to the list of library_deps.
-  endforeach(dep)
-
-  get_fq_target_name(${target_name} fq_target_name)
-  add_executable(
-    ${fq_target_name}
-    EXCLUDE_FROM_ALL
-    ${LIBC_FUZZER_SRCS}
-    ${LIBC_FUZZER_HDRS}
-  )
-  target_include_directories(
-    ${fq_target_name}
-    PRIVATE
-      ${LIBC_SOURCE_DIR}
-      ${LIBC_BUILD_DIR}
-      ${LIBC_BUILD_DIR}/include
-  )
-
-  if(library_deps)
-    target_link_libraries(${fq_target_name} PRIVATE ${library_deps})
-  endif()
-
-  set_target_properties(${fq_target_name} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
-
-  add_dependencies(
-    ${fq_target_name}
-    ${fq_deps_list}
-  )
-  add_dependencies(libc-fuzzer ${fq_target_name})
-endfunction(add_libc_fuzzer)
-
-# 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)
+include(LLVMLibCHeaderRules)
+include(LLVMLibCObjectRules)
+include(LLVMLibCLibraryRules)
+include(LLVMLibCTestRules)

libc/cmake/modules/LLVMLibCTestRules.cmake

+# Rule to add a libc unittest.
+# Usage
+#    add_libc_unittest(
+#      <target name>
+#      SUITE <name of the suite this test belongs to>
+#      SRCS  <list of .cpp files for the test>
+#      HDRS  <list of .h files for the test>
+#      DEPENDS <list of dependencies>
+#      COMPILE_OPTIONS <list of special compile options for this target>
+#    )
+function(add_libc_unittest target_name)
+  if(NOT LLVM_INCLUDE_TESTS)
+    return()
+  endif()
+
+  cmake_parse_arguments(
+    "LIBC_UNITTEST"
+    "" # No optional arguments
+    "SUITE" # Single value arguments
+    "SRCS;HDRS;DEPENDS;COMPILE_OPTIONS" # Multi-value arguments
+    ${ARGN}
+  )
+  if(NOT LIBC_UNITTEST_SRCS)
+    message(FATAL_ERROR "'add_libc_unittest' target requires a SRCS list of .cpp "
+                        "files.")
+  endif()
+  if(NOT LIBC_UNITTEST_DEPENDS)
+    message(FATAL_ERROR "'add_libc_unittest' target requires a DEPENDS list of "
+                        "'add_entrypoint_object' targets.")
+  endif()
+
+  set(library_deps "")
+  get_fq_deps_list(fq_deps_list ${LIBC_UNITTEST_DEPENDS})
+  foreach(dep IN LISTS fq_deps_list)
+    get_target_property(dep_type ${dep} "TARGET_TYPE")
+    if(${dep_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE})
+      get_target_property(obj_files ${dep} "OBJECT_FILES_RAW")
+      list(APPEND library_deps ${obj_files})
+    elseif(${dep_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})
+      get_target_property(obj_files ${dep} "OBJECT_FILES")
+      list(APPEND library_deps ${obj_files})
+    endif()
+    # TODO: Check if the dep is a normal CMake library target. If yes, then add it
+    # to the list of library_deps.
+  endforeach(dep)
+  list(REMOVE_DUPLICATES library_deps)
+
+  get_fq_target_name(${target_name} fq_target_name)
+  add_executable(
+    ${fq_target_name}
+    EXCLUDE_FROM_ALL
+    ${LIBC_UNITTEST_SRCS}
+    ${LIBC_UNITTEST_HDRS}
+  )
+  target_include_directories(
+    ${fq_target_name}
+    PRIVATE
+      ${LIBC_SOURCE_DIR}
+      ${LIBC_BUILD_DIR}
+      ${LIBC_BUILD_DIR}/include
+  )
+  if(LIBC_UNITTEST_COMPILE_OPTIONS)
+    target_compile_options(
+      ${target_name}
+      PRIVATE ${LIBC_UNITTEST_COMPILE_OPTIONS}
+    )
+  endif()
+
+  if(library_deps)
+    target_link_libraries(${fq_target_name} PRIVATE ${library_deps})
+  endif()
+
+  set_target_properties(${fq_target_name}
+    PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
+  add_dependencies(
+    ${fq_target_name}
+    ${fq_deps_list}
+  )
+
+  target_link_libraries(${fq_target_name} PRIVATE LibcUnitTest libc_test_utils)
+
+  add_custom_command(
+    TARGET ${fq_target_name}
+    POST_BUILD
+    COMMAND $<TARGET_FILE:${fq_target_name}>
+  )
+  if(LIBC_UNITTEST_SUITE)
+    add_dependencies(
+      ${LIBC_UNITTEST_SUITE}
+      ${fq_target_name}
+    )
+  endif()
+endfunction(add_libc_unittest)
+
+function(add_libc_testsuite suite_name)
+  add_custom_target(${suite_name})
+  add_dependencies(check-libc ${suite_name})
+endfunction(add_libc_testsuite)
+
+# Rule to add a fuzzer test.
+# Usage
+#    add_libc_fuzzer(
+#      <target name>
+#      SRCS  <list of .cpp files for the test>
+#      HDRS  <list of .h files for the test>
+#      DEPENDS <list of dependencies>
+#    )
+function(add_libc_fuzzer target_name)
+  cmake_parse_arguments(
+    "LIBC_FUZZER"
+    "" # No optional arguments
+    "" # Single value arguments
+    "SRCS;HDRS;DEPENDS" # Multi-value arguments
+    ${ARGN}
+  )
+  if(NOT LIBC_FUZZER_SRCS)
+    message(FATAL_ERROR "'add_libc_fuzzer' target requires a SRCS list of .cpp "
+                        "files.")
+  endif()
+  if(NOT LIBC_FUZZER_DEPENDS)
+    message(FATAL_ERROR "'add_libc_fuzzer' target requires a DEPENDS list of "
+                        "'add_entrypoint_object' targets.")
+  endif()
+
+  get_fq_deps_list(fq_deps_list ${LIBC_FUZZER_DEPENDS})
+  set(library_deps "")
+  foreach(dep IN LISTS fq_deps_list)
+    get_target_property(dep_type ${dep} "TARGET_TYPE")
+    if (dep_type)
+      string(COMPARE EQUAL ${dep_type} ${ENTRYPOINT_OBJ_TARGET_TYPE} dep_is_entrypoint)
+      if(dep_is_entrypoint)
+        get_target_property(obj_file ${dep} "OBJECT_FILES_RAW")
+        list(APPEND library_deps ${obj_file})
+        continue()
+      endif()
+    endif()
+    # TODO: Check if the dep is a normal CMake library target. If yes, then add it
+    # to the list of library_deps.
+  endforeach(dep)
+
+  get_fq_target_name(${target_name} fq_target_name)
+  add_executable(
+    ${fq_target_name}
+    EXCLUDE_FROM_ALL
+    ${LIBC_FUZZER_SRCS}
+    ${LIBC_FUZZER_HDRS}
+  )
+  target_include_directories(
+    ${fq_target_name}
+    PRIVATE
+      ${LIBC_SOURCE_DIR}
+      ${LIBC_BUILD_DIR}
+      ${LIBC_BUILD_DIR}/include
+  )
+
+  if(library_deps)
+    target_link_libraries(${fq_target_name} PRIVATE ${library_deps})
+  endif()
+
+  set_target_properties(${fq_target_name}
+      PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
+  add_dependencies(
+    ${fq_target_name}
+    ${fq_deps_list}
+  )
+  add_dependencies(libc-fuzzer ${fq_target_name})
+endfunction(add_libc_fuzzer)