libc/cmake/modules/LLVMLibCTestRules.cmake

# This is a helper function and not a build rule. It is to be used by the
# various test rules to generate the full list of object files
# recursively produced by "add_entrypoint_object" and "add_object_library"
# targets.
# Usage:
#   get_object_files_for_test(<result var>
#                             <skipped_entrypoints_var>
#                             <target0> [<target1> ...])
#
#   The list of object files is collected in <result_var>.
#   If skipped entrypoints were found, then <skipped_entrypoints_var> is
#   set to a true value.
#   targetN is either an "add_entrypoint_target" target or an
#   "add_object_library" target.
function(get_object_files_for_test result skipped_entrypoints_list)
  set(object_files "")
  set(skipped_list "")
  set(checked_list "")
  set(unchecked_list "${ARGN}")
  list(REMOVE_DUPLICATES unchecked_list)

  foreach(dep IN LISTS unchecked_list)
    if (NOT TARGET ${dep})
      # Skip tests with undefined dependencies.
      # Compiler-RT targets are added only if they are enabled. However, such targets may not be defined
      # at the time of the libc build. We should skip checking such targets.
      if (NOT ${dep} MATCHES "^RTScudo.*|^RTGwp.*")
        list(APPEND skipped_list ${dep})
      endif()
      continue()
    endif()
    get_target_property(aliased_target ${dep} "ALIASED_TARGET")
    if(aliased_target)
      # If the target is just an alias, switch to the real target.
      set(dep ${aliased_target})
    endif()

    get_target_property(dep_type ${dep} "TARGET_TYPE")
    if(NOT dep_type)
      # Skip tests with no object dependencies.
      continue()
    endif()

    get_target_property(dep_checked ${dep} "CHECK_OBJ_FOR_TESTS")

    if(dep_checked)
      # Target full dependency has already been checked.  Just use the results.
      get_target_property(dep_obj ${dep} "OBJECT_FILES_FOR_TESTS")
      get_target_property(dep_skip ${dep} "SKIPPED_LIST_FOR_TESTS")
    else()
      # Target full dependency hasn't been checked.  Recursively check its DEPS.
      set(dep_obj "${dep}")
      set(dep_skip "")

      get_target_property(indirect_deps ${dep} "DEPS")
      get_object_files_for_test(dep_obj dep_skip ${indirect_deps})

      if(${dep_type} STREQUAL ${OBJECT_LIBRARY_TARGET_TYPE})
        get_target_property(dep_object_files ${dep} "OBJECT_FILES")
        if(dep_object_files)
          list(APPEND dep_obj ${dep_object_files})
        endif()
      elseif(${dep_type} STREQUAL ${ENTRYPOINT_OBJ_TARGET_TYPE})
        get_target_property(is_skipped ${dep} "SKIPPED")
        if(is_skipped)
          list(APPEND dep_skip ${dep})
          list(REMOVE_ITEM dep_obj ${dep})
        endif()
        get_target_property(object_file_raw ${dep} "OBJECT_FILE_RAW")
        if(object_file_raw)
          list(APPEND dep_obj ${object_file_raw})
        endif()
      elseif(${dep_type} STREQUAL ${ENTRYPOINT_OBJ_VENDOR_TARGET_TYPE})
        # Skip tests for externally implemented entrypoints.
        list(APPEND dep_skip ${dep})
        list(REMOVE_ITEM dep_obj ${dep})
      endif()

      set_target_properties(${dep} PROPERTIES
        OBJECT_FILES_FOR_TESTS "${dep_obj}"
        SKIPPED_LIST_FOR_TESTS "${dep_skip}"
        CHECK_OBJ_FOR_TESTS "YES"
      )

    endif()

    list(APPEND object_files ${dep_obj})
    list(APPEND skipped_list ${dep_skip})

  endforeach(dep)

  list(REMOVE_DUPLICATES object_files)
  set(${result} ${object_files} PARENT_SCOPE)
  list(REMOVE_DUPLICATES skipped_list)
  set(${skipped_entrypoints_list} ${skipped_list} PARENT_SCOPE)

endfunction(get_object_files_for_test)


# 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>
#      LINK_LIBRARIES <list of linking libraries for this target>
#    )
function(create_libc_unittest fq_target_name)
  if(NOT LLVM_INCLUDE_TESTS)
    return()
  endif()

  cmake_parse_arguments(
    "LIBC_UNITTEST"
    "NO_RUN_POSTBUILD;C_TEST" # Optional arguments
    "SUITE;CXX_STANDARD" # Single value arguments
    "SRCS;HDRS;DEPENDS;COMPILE_OPTIONS;LINK_LIBRARIES;FLAGS" # 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()

  get_fq_deps_list(fq_deps_list ${LIBC_UNITTEST_DEPENDS})
  if(NOT LIBC_UNITTEST_C_TEST)
    list(APPEND fq_deps_list libc.src.__support.StringUtil.error_to_string
                             libc.test.UnitTest.ErrnoSetterMatcher)
  endif()
  list(REMOVE_DUPLICATES fq_deps_list)

  _get_common_test_compile_options(compile_options "${LIBC_UNITTEST_C_TEST}"
                                   "${LIBC_UNITTEST_FLAGS}")
  list(APPEND compile_options ${LIBC_UNITTEST_COMPILE_OPTIONS})

  if(SHOW_INTERMEDIATE_OBJECTS)
    message(STATUS "Adding unit test ${fq_target_name}")
    if(${SHOW_INTERMEDIATE_OBJECTS} STREQUAL "DEPS")
      foreach(dep IN LISTS LIBC_UNITTEST_DEPENDS)
        message(STATUS "  ${fq_target_name} depends on ${dep}")
      endforeach()
    endif()
  endif()

  get_object_files_for_test(
      link_object_files skipped_entrypoints_list ${fq_deps_list})
  if(skipped_entrypoints_list)
    # If a test is OS/target machine independent, it has to be skipped if the
    # OS/target machine combination does not provide any dependent entrypoints.
    # If a test is OS/target machine specific, then such a test will live is a
    # OS/target machine specific directory and will be skipped at the directory
    # level if required.
    #
    # There can potentially be a setup like this: A unittest is setup for a
    # OS/target machine independent object library, which in turn depends on a
    # machine specific object library. Such a test would be testing internals of
    # the libc and it is assumed that they will be rare in practice. So, they
    # can be skipped in the corresponding CMake files using platform specific
    # logic. This pattern is followed in the startup tests for example.
    #
    # Another pattern that is present currently is to detect machine
    # capabilities and add entrypoints and tests accordingly. That approach is
    # much lower level approach and is independent of the kind of skipping that
    # is happening here at the entrypoint level.
    if(LIBC_CMAKE_VERBOSE_LOGGING)
      set(msg "Skipping unittest ${fq_target_name} as it has missing deps: "
              "${skipped_entrypoints_list}.")
      message(STATUS ${msg})
    endif()
    return()
  endif()

  if(LIBC_UNITTEST_NO_RUN_POSTBUILD)
    set(fq_build_target_name ${fq_target_name})
  else()
    set(fq_build_target_name ${fq_target_name}.__build__)
  endif()

  add_executable(
    ${fq_build_target_name}
    EXCLUDE_FROM_ALL
    ${LIBC_UNITTEST_SRCS}
    ${LIBC_UNITTEST_HDRS}
  )
  target_include_directories(${fq_build_target_name} SYSTEM PRIVATE ${LIBC_INCLUDE_DIR})
  target_include_directories(${fq_build_target_name} PRIVATE ${LIBC_SOURCE_DIR})
  target_compile_options(${fq_build_target_name} PRIVATE ${compile_options})
  target_link_options(${fq_build_target_name} PRIVATE ${compile_options})

  if(NOT LIBC_UNITTEST_CXX_STANDARD)
    set(LIBC_UNITTEST_CXX_STANDARD ${CMAKE_CXX_STANDARD})
  endif()
  set_target_properties(
    ${fq_build_target_name}
    PROPERTIES
      CXX_STANDARD ${LIBC_UNITTEST_CXX_STANDARD}
  )

  set(link_libraries ${link_object_files})
  # Test object files will depend on LINK_LIBRARIES passed down from `add_fp_unittest`
  foreach(lib IN LISTS LIBC_UNITTEST_LINK_LIBRARIES)
    if(TARGET ${lib}.unit)
      list(APPEND link_libraries ${lib}.unit)
    else()
      list(APPEND link_libraries ${lib})
    endif()
  endforeach()

  set_target_properties(${fq_build_target_name}
    PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})

  add_dependencies(
    ${fq_build_target_name}
    ${fq_deps_list}
  )

  # LibcUnitTest should not depend on anything in LINK_LIBRARIES.
  if(NOT LIBC_UNITTEST_C_TEST)
    list(APPEND link_libraries LibcDeathTestExecutors.unit LibcTest.unit)
  endif()

  target_link_libraries(${fq_build_target_name} PRIVATE ${link_libraries})

  if(NOT LIBC_UNITTEST_NO_RUN_POSTBUILD)
    add_custom_target(
      ${fq_target_name}
      COMMAND ${fq_build_target_name}
      COMMENT "Running unit test ${fq_target_name}"
    )
  endif()

  if(LIBC_UNITTEST_SUITE)
    add_dependencies(
      ${LIBC_UNITTEST_SUITE}
      ${fq_target_name}
    )
  endif()
  add_dependencies(libc-unit-tests ${fq_target_name})
endfunction(create_libc_unittest)

function(add_libc_unittest target_name)
  add_target_with_flags(
    ${target_name}
    CREATE_TARGET create_libc_unittest
    ${ARGN}
  )
endfunction(add_libc_unittest)

function(add_libc_exhaustive_testsuite suite_name)
  add_custom_target(${suite_name})
  add_dependencies(exhaustive-check-libc ${suite_name})
endfunction(add_libc_exhaustive_testsuite)

function(add_libc_long_running_testsuite suite_name)
  add_custom_target(${suite_name})
  add_dependencies(libc-long-running-tests ${suite_name})
endfunction(add_libc_long_running_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"
    "NEED_MPFR" # Optional arguments
    "" # Single value arguments
    "SRCS;HDRS;DEPENDS;COMPILE_OPTIONS" # 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()

  list(APPEND LIBC_FUZZER_LINK_LIBRARIES "")
  if(LIBC_FUZZER_NEED_MPFR)
    if(NOT LIBC_TESTS_CAN_USE_MPFR)
      message(VERBOSE "Fuzz test ${name} will be skipped as MPFR library is not available.")
      return()
    endif()
    list(APPEND LIBC_FUZZER_LINK_LIBRARIES mpfr gmp)
  endif()


  get_fq_target_name(${target_name} fq_target_name)
  get_fq_deps_list(fq_deps_list ${LIBC_FUZZER_DEPENDS})
  get_object_files_for_test(
      link_object_files skipped_entrypoints_list ${fq_deps_list})
  if(skipped_entrypoints_list)
    if(LIBC_CMAKE_VERBOSE_LOGGING)
      set(msg "Skipping fuzzer target ${fq_target_name} as it has missing deps: "
              "${skipped_entrypoints_list}.")
      message(STATUS ${msg})
    endif()
    add_custom_target(${fq_target_name})

    # A post build custom command is used to avoid running the command always.
    add_custom_command(
      TARGET ${fq_target_name}
      POST_BUILD
      COMMAND ${CMAKE_COMMAND} -E echo ${msg}
    )
    return()
  endif()

  add_executable(
    ${fq_target_name}
    EXCLUDE_FROM_ALL
    ${LIBC_FUZZER_SRCS}
    ${LIBC_FUZZER_HDRS}
  )
  target_include_directories(${fq_target_name} SYSTEM PRIVATE ${LIBC_INCLUDE_DIR})
  target_include_directories(${fq_target_name} PRIVATE ${LIBC_SOURCE_DIR})

  target_link_libraries(${fq_target_name} PRIVATE
    ${link_object_files}
    ${LIBC_FUZZER_LINK_LIBRARIES}
  )

  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})

  target_compile_options(${fq_target_name}
    PRIVATE
    ${LIBC_FUZZER_COMPILE_OPTIONS})

endfunction(add_libc_fuzzer)

# Get libgcc_s to be used in hermetic and integration tests.
if(NOT MSVC AND NOT LIBC_CC_SUPPORTS_NOSTDLIBPP)
  execute_process(COMMAND ${CMAKE_CXX_COMPILER} -print-file-name=libgcc_s.so.1
                  OUTPUT_VARIABLE LIBGCC_S_LOCATION)
  string(STRIP ${LIBGCC_S_LOCATION} LIBGCC_S_LOCATION)
endif()

# DEPRECATED: Use add_hermetic_test instead.
#
# Rule to add an integration test. An integration test is like a unit test
# but does not use the system libc. Not even the startup objects from the
# system libc are linked in to the final executable. The final exe is fully
# statically linked. The libc that the final exe links to consists of only
# the object files of the DEPENDS targets.
#
# Usage:
#   add_integration_test(
#     <target name>
#     SUITE <the suite to which the test should belong>
#     SRCS <src1.cpp> [src2.cpp ...]
#     HDRS [hdr1.cpp ...]
#     DEPENDS <list of entrypoint or other object targets>
#     ARGS <list of command line arguments to be passed to the test>
#     ENV <list of environment variables to set before running the test>
#     COMPILE_OPTIONS <list of special compile options for this target>
#   )
#
# The DEPENDS list can be empty. If not empty, it should be a list of
# targets added with add_entrypoint_object or add_object_library.
function(add_integration_test test_name)
  get_fq_target_name(${test_name} fq_target_name)
  set(supported_targets gpu linux)
  if(NOT (${LIBC_TARGET_OS} IN_LIST supported_targets))
    message(STATUS "Skipping ${fq_target_name} as it is not available on ${LIBC_TARGET_OS}.")
    return()
  endif()
  cmake_parse_arguments(
    "INTEGRATION_TEST"
    "" # No optional arguments
    "SUITE" # Single value arguments
    "SRCS;HDRS;DEPENDS;ARGS;ENV;COMPILE_OPTIONS;LOADER_ARGS" # Multi-value arguments
    ${ARGN}
  )

  if(NOT INTEGRATION_TEST_SUITE)
    message(FATAL_ERROR "SUITE not specified for ${fq_target_name}")
  endif()
  if(NOT INTEGRATION_TEST_SRCS)
    message(FATAL_ERROR "The SRCS list for add_integration_test is missing.")
  endif()
  if(NOT TARGET libc.startup.${LIBC_TARGET_OS}.crt1)
    message(FATAL_ERROR "The 'crt1' target for the integration test is missing.")
  endif()

  get_fq_target_name(${test_name}.libc fq_libc_target_name)

  get_fq_deps_list(fq_deps_list ${INTEGRATION_TEST_DEPENDS})
  list(APPEND fq_deps_list
      # All integration tests use the operating system's startup object with the
      # integration test object and need to inherit the same dependencies.
      libc.startup.${LIBC_TARGET_OS}.crt1
      libc.test.IntegrationTest.test
      # We always add the memory functions objects. This is because the
      # compiler's codegen can emit calls to the C memory functions.
      libc.src.string.bcmp
      libc.src.string.bzero
      libc.src.string.memcmp
      libc.src.string.memcpy
      libc.src.string.memmove
      libc.src.string.memset
  )

  if(libc.src.compiler.__stack_chk_fail IN_LIST TARGET_LLVMLIBC_ENTRYPOINTS)
    # __stack_chk_fail should always be included if supported to allow building
    # libc with the stack protector enabled.
    list(APPEND fq_deps_list libc.src.compiler.__stack_chk_fail)
  endif()

  list(REMOVE_DUPLICATES fq_deps_list)

  # TODO: Instead of gathering internal object files from entrypoints,
  # collect the object files with public names of entrypoints.
  get_object_files_for_test(
      link_object_files skipped_entrypoints_list ${fq_deps_list})
  if(skipped_entrypoints_list)
    if(LIBC_CMAKE_VERBOSE_LOGGING)
      set(msg "Skipping integration test ${fq_target_name} as it has missing deps: "
              "${skipped_entrypoints_list}.")
      message(STATUS ${msg})
    endif()
    return()
  endif()
  list(REMOVE_DUPLICATES link_object_files)

  # Make a library of all deps
  add_library(
    ${fq_target_name}.__libc__
    STATIC
    EXCLUDE_FROM_ALL
    ${link_object_files}
  )
  set_target_properties(${fq_target_name}.__libc__
      PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
  set_target_properties(${fq_target_name}.__libc__
      PROPERTIES ARCHIVE_OUTPUT_NAME ${fq_target_name}.libc)

  set(fq_build_target_name ${fq_target_name}.__build__)
  add_executable(
    ${fq_build_target_name}
    EXCLUDE_FROM_ALL
    ${INTEGRATION_TEST_SRCS}
    ${INTEGRATION_TEST_HDRS}
  )
  set_target_properties(${fq_build_target_name}
      PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
  target_include_directories(${fq_build_target_name} SYSTEM PRIVATE ${LIBC_INCLUDE_DIR})
  target_include_directories(${fq_build_target_name} PRIVATE ${LIBC_SOURCE_DIR})

  _get_hermetic_test_compile_options(compile_options "")
  target_compile_options(${fq_build_target_name} PRIVATE
                         ${compile_options} ${INTEGRATION_TEST_COMPILE_OPTIONS})

  if(LIBC_TARGET_ARCHITECTURE_IS_AMDGPU)
    target_link_options(${fq_build_target_name} PRIVATE
      ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
      -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto
      "-Wl,-mllvm,-amdgpu-lower-global-ctor-dtor=0" -nostdlib -static
      "-Wl,-mllvm,-amdhsa-code-object-version=${LIBC_GPU_CODE_OBJECT_VERSION}")
  elseif(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
    target_link_options(${fq_build_target_name} PRIVATE
      ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
      "-Wl,--suppress-stack-size-warning"
      "-Wl,-mllvm,-nvptx-lower-global-ctor-dtor=1"
      "-Wl,-mllvm,-nvptx-emit-init-fini-kernel"
      -march=${LIBC_GPU_TARGET_ARCHITECTURE} -nostdlib -static
      "--cuda-path=${LIBC_CUDA_ROOT}")
  elseif(LIBC_CC_SUPPORTS_NOSTDLIBPP)
    target_link_options(${fq_build_target_name} PRIVATE -nolibc -nostartfiles -nostdlib++ -static)
  else()
    # Older version of gcc does not support `nostdlib++` flag.  We use
    # `nostdlib` and link against libgcc_s, which cannot be linked statically.
    target_link_options(${fq_build_target_name} PRIVATE -nolibc -nostartfiles -nostdlib)
    list(APPEND link_libraries ${LIBGCC_S_LOCATION})
  endif()
  target_link_libraries(
    ${fq_build_target_name}
    ${fq_target_name}.__libc__
    libc.startup.${LIBC_TARGET_OS}.crt1
    libc.test.IntegrationTest.test
  )
  add_dependencies(${fq_build_target_name}
                   libc.test.IntegrationTest.test
                   ${INTEGRATION_TEST_DEPENDS})

  # Tests on the GPU require an external loader utility to launch the kernel.
  if(TARGET libc.utils.gpu.loader)
    add_dependencies(${fq_build_target_name} libc.utils.gpu.loader)
    get_target_property(gpu_loader_exe libc.utils.gpu.loader "EXECUTABLE")
  endif()

  # We have to use a separate var to store the command as a list because
  # the COMMAND option of `add_custom_target` cannot handle empty vars in the
  # command. For example, if INTEGRATION_TEST_ENV is empty, the actual
  # command also will not run. So, we use this list and tell `add_custom_target`
  # to expand the list (by including the option COMMAND_EXPAND_LISTS). This
  # makes `add_custom_target` construct the correct command and execute it.
  set(test_cmd
      ${INTEGRATION_TEST_ENV}
      $<$<BOOL:${LIBC_TARGET_OS_IS_GPU}>:${gpu_loader_exe}>
      ${CMAKE_CROSSCOMPILING_EMULATOR}
      ${INTEGRATION_TEST_LOADER_ARGS}
      $<TARGET_FILE:${fq_build_target_name}> ${INTEGRATION_TEST_ARGS})
  add_custom_target(
    ${fq_target_name}
    COMMAND ${test_cmd}
    COMMAND_EXPAND_LISTS
    COMMENT "Running integration test ${fq_target_name}"
  )
  add_dependencies(${INTEGRATION_TEST_SUITE} ${fq_target_name})
endfunction(add_integration_test)

# Rule to add a hermetic program. A hermetic program is one whose executable is fully
# statically linked and consists of pieces drawn only from LLVM's libc. Nothing,
# including the startup objects, come from the system libc.
#
# For the GPU, these can be either tests or benchmarks, depending on the value
# of the LINK_LIBRARIES arg.
#
# Usage:
#   add_libc_hermetic(
#     <target name>
#     SUITE <the suite to which the test should belong>
#     SRCS <src1.cpp> [src2.cpp ...]
#     HDRS [hdr1.cpp ...]
#     DEPENDS <list of entrypoint or other object targets>
#     ARGS <list of command line arguments to be passed to the test>
#     ENV <list of environment variables to set before running the test>
#     COMPILE_OPTIONS <list of special compile options for the test>
#     LINK_LIBRARIES <list of linking libraries for this target>
#     LOADER_ARGS <list of special args to loaders (like the GPU loader)>
#   )
function(add_libc_hermetic test_name)
  if(NOT TARGET libc.startup.${LIBC_TARGET_OS}.crt1)
    message(VERBOSE "Skipping ${fq_target_name} as it is not available on ${LIBC_TARGET_OS}.")
    return()
  endif()
  cmake_parse_arguments(
    "HERMETIC_TEST"
    "IS_GPU_BENCHMARK" # Optional arguments
    "SUITE" # Single value arguments
    "SRCS;HDRS;DEPENDS;ARGS;ENV;COMPILE_OPTIONS;LINK_LIBRARIES;LOADER_ARGS" # Multi-value arguments
    ${ARGN}
  )

  if(NOT HERMETIC_TEST_SUITE)
    message(FATAL_ERROR "SUITE not specified for ${fq_target_name}")
  endif()
  if(NOT HERMETIC_TEST_SRCS)
    message(FATAL_ERROR "The SRCS list for add_integration_test is missing.")
  endif()

  get_fq_target_name(${test_name} fq_target_name)
  get_fq_target_name(${test_name}.libc fq_libc_target_name)

  get_fq_deps_list(fq_deps_list ${HERMETIC_TEST_DEPENDS})
  list(APPEND fq_deps_list
      # Hermetic tests use the platform's startup object. So, their deps also
      # have to be collected.
      libc.startup.${LIBC_TARGET_OS}.crt1
      # We always add the memory functions objects. This is because the
      # compiler's codegen can emit calls to the C memory functions.
      libc.src.string.bcmp
      libc.src.string.bzero
      libc.src.string.memcmp
      libc.src.string.memcpy
      libc.src.string.memmove
      libc.src.string.memset
      libc.src.__support.StringUtil.error_to_string
  )

  if(libc.src.compiler.__stack_chk_fail IN_LIST TARGET_LLVMLIBC_ENTRYPOINTS)
    # __stack_chk_fail should always be included if supported to allow building
    # libc with the stack protector enabled.
    list(APPEND fq_deps_list libc.src.compiler.__stack_chk_fail)
  endif()

  if(libc.src.time.clock IN_LIST TARGET_LLVMLIBC_ENTRYPOINTS)
    # We will link in the 'clock' implementation if it exists for test timing.
    list(APPEND fq_deps_list libc.src.time.clock)
  endif()

  list(REMOVE_DUPLICATES fq_deps_list)

  # TODO: Instead of gathering internal object files from entrypoints,
  # collect the object files with public names of entrypoints.
  get_object_files_for_test(
      link_object_files skipped_entrypoints_list ${fq_deps_list})
  if(skipped_entrypoints_list)
    if(LIBC_CMAKE_VERBOSE_LOGGING)
      set(msg "Skipping hermetic test ${fq_target_name} as it has missing deps: "
              "${skipped_entrypoints_list}.")
      message(STATUS ${msg})
    endif()
    return()
  endif()
  list(REMOVE_DUPLICATES link_object_files)

  # Make a library of all deps
  add_library(
    ${fq_target_name}.__libc__
    STATIC
    EXCLUDE_FROM_ALL
    ${link_object_files}
  )
  set_target_properties(${fq_target_name}.__libc__
      PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
  set_target_properties(${fq_target_name}.__libc__
      PROPERTIES ARCHIVE_OUTPUT_NAME ${fq_target_name}.libc)

  set(fq_build_target_name ${fq_target_name}.__build__)
  add_executable(
    ${fq_build_target_name}
    EXCLUDE_FROM_ALL
    ${HERMETIC_TEST_SRCS}
    ${HERMETIC_TEST_HDRS}
  )
  set_target_properties(${fq_build_target_name}
    PROPERTIES
      RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
      #OUTPUT_NAME ${fq_target_name}
  )

  target_include_directories(${fq_build_target_name} SYSTEM PRIVATE ${LIBC_INCLUDE_DIR})
  target_include_directories(${fq_build_target_name} PRIVATE ${LIBC_SOURCE_DIR})
  _get_hermetic_test_compile_options(compile_options "")
  target_compile_options(${fq_build_target_name} PRIVATE
                         ${compile_options}
                         ${HERMETIC_TEST_COMPILE_OPTIONS})

  set(link_libraries "")
  foreach(lib IN LISTS HERMETIC_TEST_LINK_LIBRARIES)
    if(TARGET ${lib}.hermetic)
      list(APPEND link_libraries ${lib}.hermetic)
    else()
      list(APPEND link_libraries ${lib})
    endif()
  endforeach()

  if(LIBC_TARGET_ARCHITECTURE_IS_AMDGPU)
    target_link_options(${fq_build_target_name} PRIVATE
      ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
      -mcpu=${LIBC_GPU_TARGET_ARCHITECTURE} -flto
      "-Wl,-mllvm,-amdgpu-lower-global-ctor-dtor=0" -nostdlib -static
      "-Wl,-mllvm,-amdhsa-code-object-version=${LIBC_GPU_CODE_OBJECT_VERSION}")
  elseif(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
    target_link_options(${fq_build_target_name} PRIVATE
      ${LIBC_COMPILE_OPTIONS_DEFAULT} -Wno-multi-gpu
      "-Wl,--suppress-stack-size-warning"
      "-Wl,-mllvm,-nvptx-lower-global-ctor-dtor=1"
      "-Wl,-mllvm,-nvptx-emit-init-fini-kernel"
      -march=${LIBC_GPU_TARGET_ARCHITECTURE} -nostdlib -static
      "--cuda-path=${LIBC_CUDA_ROOT}")
  elseif(LIBC_CC_SUPPORTS_NOSTDLIBPP)
    target_link_options(${fq_build_target_name} PRIVATE -nolibc -nostartfiles -nostdlib++ -static)
  else()
    # Older version of gcc does not support `nostdlib++` flag.  We use
    # `nostdlib` and link against libgcc_s, which cannot be linked statically.
    target_link_options(${fq_build_target_name} PRIVATE -nolibc -nostartfiles -nostdlib)
    list(APPEND link_libraries ${LIBGCC_S_LOCATION})
  endif()
  target_link_libraries(
    ${fq_build_target_name}
    PRIVATE
      libc.startup.${LIBC_TARGET_OS}.crt1
      ${link_libraries}
      LibcHermeticTestSupport.hermetic
      ${fq_target_name}.__libc__)
  add_dependencies(${fq_build_target_name}
                   LibcTest.hermetic
                   libc.test.UnitTest.ErrnoSetterMatcher
                   ${fq_deps_list})
  # TODO: currently the dependency chain is broken such that getauxval cannot properly
  # propagate to hermetic tests. This is a temporary workaround.
  if (LIBC_TARGET_ARCHITECTURE_IS_AARCH64)
    target_link_libraries(
      ${fq_build_target_name}
      PRIVATE
        libc.src.sys.auxv.getauxval
    )
  endif()

  # Tests on the GPU require an external loader utility to launch the kernel.
  if(TARGET libc.utils.gpu.loader)
    add_dependencies(${fq_build_target_name} libc.utils.gpu.loader)
    get_target_property(gpu_loader_exe libc.utils.gpu.loader "EXECUTABLE")
  endif()

  set(test_cmd ${HERMETIC_TEST_ENV}
      $<$<BOOL:${LIBC_TARGET_OS_IS_GPU}>:${gpu_loader_exe}> ${CMAKE_CROSSCOMPILING_EMULATOR} ${HERMETIC_TEST_LOADER_ARGS}
      $<TARGET_FILE:${fq_build_target_name}> ${HERMETIC_TEST_ARGS})
  add_custom_target(
    ${fq_target_name}
    DEPENDS ${fq_target_name}-cmd
  )

  add_custom_command(
    OUTPUT ${fq_target_name}-cmd
    COMMAND ${test_cmd}
    COMMAND_EXPAND_LISTS
    COMMENT "Running hermetic test ${fq_target_name}"
    ${LIBC_HERMETIC_TEST_JOB_POOL}
  )

  set_source_files_properties(${fq_target_name}-cmd
    PROPERTIES
      SYMBOLIC "TRUE"
  )

  add_dependencies(${HERMETIC_TEST_SUITE} ${fq_target_name})
  if(NOT ${HERMETIC_TEST_IS_GPU_BENCHMARK})
    # If it is a benchmark, it will already have been added to the
    # gpu-benchmark target
    add_dependencies(libc-hermetic-tests ${fq_target_name})
  endif()
endfunction(add_libc_hermetic)

# A convenience function to add both a unit test as well as a hermetic test.
function(add_libc_test test_name)
  cmake_parse_arguments(
    "LIBC_TEST"
    "UNIT_TEST_ONLY;HERMETIC_TEST_ONLY" # Optional arguments
    "" # Single value arguments
    "" # Multi-value arguments
    ${ARGN}
  )
  if(LIBC_ENABLE_UNITTESTS AND NOT LIBC_TEST_HERMETIC_TEST_ONLY)
    add_libc_unittest(${test_name}.__unit__ ${LIBC_TEST_UNPARSED_ARGUMENTS})
  endif()
  if(LIBC_ENABLE_HERMETIC_TESTS AND NOT LIBC_TEST_UNIT_TEST_ONLY)
    add_libc_hermetic(
      ${test_name}.__hermetic__
      LINK_LIBRARIES
        LibcTest.hermetic
      ${LIBC_TEST_UNPARSED_ARGUMENTS}
    )
    get_fq_target_name(${test_name} fq_test_name)
    if(TARGET ${fq_test_name}.__hermetic__ AND TARGET ${fq_test_name}.__unit__)
      # Tests like the file tests perform file operations on disk file. If we
      # don't chain up the unit test and hermetic test, then those tests will
      # step on each other's files.
      add_dependencies(${fq_test_name}.__hermetic__ ${fq_test_name}.__unit__)
    endif()
  endif()
endfunction(add_libc_test)