CMakeLists.txt

cmake_minimum_required(VERSION 3.20.0)

# Include LLVM's cmake policies.
if(NOT DEFINED LLVM_COMMON_CMAKE_UTILS)
  set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
endif()
include(${LLVM_COMMON_CMAKE_UTILS}/Modules/CMakePolicy.cmake
  NO_POLICY_SCOPE)

# Default to C++17
set(CMAKE_CXX_STANDARD 17)

list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules")

# The top-level source directory.
set(LIBC_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
# The top-level directory in which libc is being built.
set(LIBC_BUILD_DIR ${CMAKE_CURRENT_BINARY_DIR})

set(LIBC_ENABLE_USE_BY_CLANG OFF CACHE BOOL "Whether or not to place libc in a build directory findable by a just built clang")

if(LLVM_LIBC_FULL_BUILD OR LIBC_GPU_BUILD OR LIBC_GPU_ARCHITECTURES)
  if(NOT LIBC_HDRGEN_EXE)
    # We need to set up hdrgen first since other targets depend on it.
    add_subdirectory(utils/LibcTableGenUtil)
    add_subdirectory(utils/HdrGen)
  else()
    message(STATUS "Will use ${LIBC_HDRGEN_EXE} for libc header generation.")
  endif()
endif()

option(LIBC_HDRGEN_ONLY "Only build the 'libc-hdrgen' executable" OFF)
if(("libc" IN_LIST LLVM_ENABLE_RUNTIMES AND NOT LLVM_RUNTIMES_BUILD) OR 
   LIBC_HDRGEN_ONLY)
  # When libc is build as part of the runtimes/bootstrap build's CMake run, we
  # only need to build the host tools to build the libc. So, we just do enough
  # to build libc-hdrgen and return.

  # Always make the RPC server availible to other projects for GPU mode.
  if(LIBC_GPU_BUILD OR LIBC_GPU_ARCHITECTURES)
    add_subdirectory(utils/gpu/server)
  endif()
  return()
endif()

option(LIBC_CMAKE_VERBOSE_LOGGING
       "Log details warnings and notifications during CMake configuration." OFF)
# Path libc/scripts directory.
set(LIBC_BUILD_SCRIPTS_DIR "${LIBC_SOURCE_DIR}/utils/build_scripts")

# Flags to pass down to the compiler while building the libc functions.
set(LIBC_COMPILE_OPTIONS_DEFAULT "" CACHE STRING "Architecture to tell clang to optimize for (e.g. -march=... or -mcpu=...)")

include(common_libc_tuners.cmake)

list(APPEND LIBC_COMPILE_OPTIONS_DEFAULT ${LIBC_COMMON_TUNE_OPTIONS})

# Check --print-resource-dir to find the compiler resource dir if this flag
# is supported by the compiler.
execute_process(
  OUTPUT_STRIP_TRAILING_WHITESPACE
  COMMAND ${CMAKE_CXX_COMPILER} --print-resource-dir
  RESULT_VARIABLE COMMAND_RETURN_CODE
  OUTPUT_VARIABLE COMPILER_RESOURCE_DIR
)
# Retrieve the host compiler's resource dir.
if(COMMAND_RETURN_CODE EQUAL 0)
  set(COMPILER_RESOURCE_DIR
    "${COMPILER_RESOURCE_DIR}" CACHE PATH "path to compiler resource dir"
  )
  message(STATUS "Set COMPILER_RESOURCE_DIR to "
                 "${COMPILER_RESOURCE_DIR} using --print-resource-dir")
else()
  set(COMPILER_RESOURCE_DIR OFF)
  message(STATUS "COMPILER_RESOURCE_DIR not set
                  --print-resource-dir not supported by host compiler")
endif()

option(LLVM_LIBC_FULL_BUILD "Build and test LLVM libc as if it is the full libc" OFF)
option(LLVM_LIBC_IMPLEMENTATION_DEFINED_TEST_BEHAVIOR "Build LLVM libc tests assuming our implementation-defined behavior" ON)
option(LLVM_LIBC_ENABLE_LINTING "Enables linting of libc source files" OFF)

option(LIBC_GPU_BUILD "Build libc for the GPU. All CPU build options will be ignored." OFF)
set(LIBC_TARGET_TRIPLE "" CACHE STRING "The target triple for the libc build.")

set(LIBC_ENABLE_UNITTESTS ON)
set(LIBC_ENABLE_HERMETIC_TESTS ${LLVM_LIBC_FULL_BUILD})

# Defines LIBC_TARGET_ARCHITECTURE and associated macros.
include(LLVMLibCArchitectures)

if(LIBC_TARGET_ARCHITECTURE_IS_GPU)
  set(LIBC_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/include)
  set(LIBC_INSTALL_INCLUDE_DIR ${CMAKE_INSTALL_INCLUDEDIR}/gpu-none-llvm)
  set(LIBC_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
elseif(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND LIBC_ENABLE_USE_BY_CLANG)
  set(LIBC_INCLUDE_DIR ${LLVM_BINARY_DIR}/include/${LLVM_DEFAULT_TARGET_TRIPLE})
  set(LIBC_INSTALL_INCLUDE_DIR ${CMAKE_INSTALL_INCLUDEDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
  set(LIBC_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
else()
  if(NOT LIBC_ENABLE_USE_BY_CLANG)
    set(LIBC_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/include)
    set(LIBC_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/lib)
  elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
    set(LIBC_INCLUDE_DIR ${LLVM_BINARY_DIR}/include)
    set(LIBC_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
  else()
    set(LIBC_INCLUDE_DIR ${CMAKE_BINARY_DIR}/include)
    set(LIBC_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
  endif()
  set(LIBC_INSTALL_INCLUDE_DIR ${CMAKE_INSTALL_INCLUDEDIR})
endif()

if(LIBC_TARGET_ARCHITECTURE_IS_GPU)
  include(prepare_libc_gpu_build)
  set(LIBC_ENABLE_UNITTESTS OFF)
endif()

include(LLVMLibCCheckMPFR)

if(LLVM_LIBC_CLANG_TIDY)
  set(LLVM_LIBC_ENABLE_LINTING ON)
endif()

if(LLVM_LIBC_ENABLE_LINTING)
  if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
    set(LLVM_LIBC_ENABLE_LINTING OFF)
    message(WARNING "C++ compiler is not clang++, linting with be disabled.")
  else()
    if (NOT LLVM_LIBC_CLANG_TIDY)
      find_program(LLVM_LIBC_CLANG_TIDY NAMES clang-tidy)
    endif()

    if(LLVM_LIBC_CLANG_TIDY)
      # Check clang-tidy major version.
      execute_process(COMMAND ${LLVM_LIBC_CLANG_TIDY} "--version"
                      OUTPUT_VARIABLE CLANG_TIDY_OUTPUT)
      string(REGEX MATCH "[0-9]+" CLANG_TIDY_VERSION "${CLANG_TIDY_OUTPUT}")
      string(REGEX MATCH "[0-9]+" CLANG_MAJOR_VERSION
             "${CMAKE_CXX_COMPILER_VERSION}")
      if(NOT CLANG_TIDY_VERSION EQUAL CLANG_MAJOR_VERSION)
        set(LLVM_LIBC_ENABLE_LINTING OFF)
        message(WARNING "
          'clang-tidy' (version ${CLANG_TIDY_VERSION}) is not the same as
          'clang' (version ${CLANG_MAJOR_VERSION}).  Linting will
          be disabled.

          The path to the clang-tidy binary can be set manually by passing
          -DLLVM_LIBC_CLANG_TIDY=<path/to/clang-tidy> to CMake.")
      endif()
      add_custom_target(libc-lint)
    else()
      message(FATAL_ERROR "
        Linting is enabled but 'clang-tidy' is not found!

        The path to the clang-tidy binary can be set manually by passing
        -DLLVM_LIBC_CLANG_TIDY=<path/to/clang-tidy> to CMake.

        To disable linting set LLVM_LIBC_ENABLE_LINTING to OFF
        (pass -DLLVM_LIBC_ENABLE_LINTING=OFF to cmake).")
    endif()
  endif()
endif()

option(LLVM_LIBC_INCLUDE_SCUDO "Include the SCUDO standalone as the allocator for LLVM libc" OFF)
if(LLVM_LIBC_INCLUDE_SCUDO)
  if (NOT "compiler-rt" IN_LIST LLVM_ENABLE_PROJECTS)
    message(FATAL_ERROR "SCUDO cannot be included without adding compiler-rt to LLVM_ENABLE_PROJECTS")
  endif()
endif()

option(LIBC_INCLUDE_DOCS "Build the libc documentation." ${LLVM_INCLUDE_DOCS})

include(CMakeParseArguments)
include(LLVMLibCCheckCpuFeatures)
include(LLVMLibCRules)

if(EXISTS "${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/${LIBC_TARGET_ARCHITECTURE}/entrypoints.txt")
  set(entrypoint_file "${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/${LIBC_TARGET_ARCHITECTURE}/entrypoints.txt")
elseif(EXISTS "${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/entrypoints.txt")
  set(entrypoint_file "${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/entrypoints.txt")
else()
  message(FATAL_ERROR "entrypoints.txt file for the target platform '${LIBC_TARGET_OS}/${LIBC_TARGET_ARCHITECTURE}' not found.")
endif()
include(${entrypoint_file})

if(EXISTS "${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/${LIBC_TARGET_ARCHITECTURE}/headers.txt")
  include("${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/${LIBC_TARGET_ARCHITECTURE}/headers.txt")
elseif(EXISTS "${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/headers.txt")
  include("${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/headers.txt")
endif()

set(TARGET_ENTRYPOINT_NAME_LIST "")
foreach(entrypoint IN LISTS TARGET_LLVMLIBC_ENTRYPOINTS)
  string(FIND ${entrypoint} "." last_dot_loc REVERSE)
  if(${last_dot_loc} EQUAL -1)
    message(FATAL "Invalid entrypoint target name ${entrypoint}; Expected a '.' "
                  "(dot) in the name.")
  endif()
  math(EXPR name_loc "${last_dot_loc} + 1")
  string(SUBSTRING ${entrypoint} ${name_loc} -1 entrypoint_name)
  list(APPEND TARGET_ENTRYPOINT_NAME_LIST ${entrypoint_name})
endforeach()

set(LIBC_INSTALL_DEPENDS)
if(LLVM_LIBC_FULL_BUILD)
  set(LIBC_INSTALL_DEPENDS "install-libc-static-archives;install-libc-headers")
  if(NOT LIBC_TARGET_OS_IS_BAREMETAL)
    # For now we will disable libc-startup installation for baremetal. The
    # correct way to do it would be to make a hookable startup for baremetal
    # and install it as part of the libc installation.
    list(APPEND LIBC_INSTALL_DEPENDS "libc-startup")
  endif()
else()
  set(LIBC_INSTALL_DEPENDS install-libc-static-archives)
endif()

add_subdirectory(include)
add_subdirectory(config)
add_subdirectory(src)
add_subdirectory(utils)

if(LLVM_LIBC_FULL_BUILD)
  # The startup system can potentially depend on the library components so add
  # it after the library implementation directories.
  add_subdirectory(startup)
endif()

# The lib and test directories are added at the very end as tests
# and libraries potentially draw from the components present in all
# of the other directories.
# TODO: Add testing support for the libc GPU target.
add_subdirectory(lib)
if(LLVM_INCLUDE_TESTS)
  add_subdirectory(test)
  add_subdirectory(fuzzing)
endif()

if(LIBC_INCLUDE_BENCHMARKS)
  add_subdirectory(benchmarks)
endif()

if (LIBC_INCLUDE_DOCS)
  add_subdirectory(docs)
endif()


if(LLVM_LIBC_FULL_BUILD)
  add_llvm_install_targets(
    install-libc-headers
    DEPENDS libc-headers
    COMPONENT libc-headers
  )
endif()

add_llvm_install_targets(
  install-libc
  DEPENDS ${LIBC_INSTALL_DEPENDS}
  COMPONENT libc
)