# CMake build for CompilerRT.
#
# An important constraint of the build is that it only produces libraries
# based on the ability of the host toolchain to target various platforms.

cmake_minimum_required(VERSION 3.13.4)

# Check if compiler-rt is built as a standalone project.
if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR COMPILER_RT_STANDALONE_BUILD)
  project(CompilerRT C CXX ASM)
  set(COMPILER_RT_STANDALONE_BUILD TRUE)
  set_property(GLOBAL PROPERTY USE_FOLDERS ON)
  if ("${CMAKE_VERSION}" VERSION_LESS "3.20.0")
    message(WARNING
      "Your CMake version is ${CMAKE_VERSION}. Starting with LLVM 17.0.0, the "
      "minimum version of CMake required to build LLVM will become 3.20.0, and "
      "using an older CMake will become an error. Please upgrade your CMake to "
      "at least 3.20.0 now to avoid issues in the future!")
  endif()
endif()

set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")

# Add path for custom compiler-rt modules.
list(INSERT CMAKE_MODULE_PATH 0
  "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
  "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
  "${LLVM_COMMON_CMAKE_UTILS}"
  "${LLVM_COMMON_CMAKE_UTILS}/Modules"
  )

if(CMAKE_CONFIGURATION_TYPES)
  set(CMAKE_CFG_RESOLVED_INTDIR "${CMAKE_CFG_INTDIR}/")
else()
  set(CMAKE_CFG_RESOLVED_INTDIR "")
endif()

include(SetPlatformToolchainTools)
include(base-config-ix)
include(CompilerRTUtils)
include(CMakeDependentOption)

option(COMPILER_RT_BUILD_BUILTINS "Build builtins" ON)
mark_as_advanced(COMPILER_RT_BUILD_BUILTINS)
option(COMPILER_RT_DISABLE_AARCH64_FMV "Disable AArch64 Function Multi Versioning support" OFF)
mark_as_advanced(COMPILER_RT_DISABLE_AARCH64_FMV)
option(COMPILER_RT_BUILD_CRT "Build crtbegin.o/crtend.o" ON)
mark_as_advanced(COMPILER_RT_BUILD_CRT)
option(COMPILER_RT_CRT_USE_EH_FRAME_REGISTRY "Use eh_frame in crtbegin.o/crtend.o" ON)
mark_as_advanced(COMPILER_RT_CRT_USE_EH_FRAME_REGISTRY)
option(COMPILER_RT_BUILD_SANITIZERS "Build sanitizers" ON)
mark_as_advanced(COMPILER_RT_BUILD_SANITIZERS)
option(COMPILER_RT_BUILD_XRAY "Build xray" ON)
mark_as_advanced(COMPILER_RT_BUILD_XRAY)
option(COMPILER_RT_BUILD_LIBFUZZER "Build libFuzzer" ON)
mark_as_advanced(COMPILER_RT_BUILD_LIBFUZZER)
option(COMPILER_RT_BUILD_PROFILE "Build profile runtime" ON)
mark_as_advanced(COMPILER_RT_BUILD_PROFILE)
option(COMPILER_RT_BUILD_MEMPROF "Build memory profiling runtime" ON)
mark_as_advanced(COMPILER_RT_BUILD_MEMPROF)
option(COMPILER_RT_BUILD_XRAY_NO_PREINIT "Build xray with no preinit patching" OFF)
mark_as_advanced(COMPILER_RT_BUILD_XRAY_NO_PREINIT)
option(COMPILER_RT_BUILD_ORC "Build ORC runtime" ON)
mark_as_advanced(COMPILER_RT_BUILD_ORC)
option(COMPILER_RT_BUILD_GWP_ASAN "Build GWP-ASan, and link it into SCUDO" ON)
mark_as_advanced(COMPILER_RT_BUILD_GWP_ASAN)
option(COMPILER_RT_ENABLE_CET "Build Compiler RT with CET enabled" OFF)

option(COMPILER_RT_SCUDO_STANDALONE_SYSROOT_PATH "Set custom sysroot for building SCUDO standalone" OFF)
mark_as_advanced(COMPILER_RT_SCUDO_STANDALONE_SYSROOT_PATH)
option(COMPILER_RT_SCUDO_STANDALONE_BUILD_SHARED "Build SCUDO standalone for shared libraries" ON)
mark_as_advanced(COMPILER_RT_SCUDO_STANDALONE_BUILD_SHARED)
option(COMPILER_RT_BUILD_SCUDO_STANDALONE_WITH_LLVM_LIBC "Build SCUDO standalone with LLVM's libc headers" OFF)
mark_as_advanced(COMPILER_RT_BUILD_SCUDO_STANDALONE_WITH_LLVM_LIBC)

if(FUCHSIA)
  set(COMPILER_RT_HWASAN_WITH_INTERCEPTORS_DEFAULT OFF)
else()
  set(COMPILER_RT_HWASAN_WITH_INTERCEPTORS_DEFAULT ON)
endif()
set(COMPILER_RT_HWASAN_WITH_INTERCEPTORS ${COMPILER_RT_HWASAN_WITH_INTERCEPTORS_DEFAULT} CACHE BOOL "Enable libc interceptors in HWASan (testing mode)")

set(COMPILER_RT_BAREMETAL_BUILD OFF CACHE BOOL
  "Build for a bare-metal target.")

if (COMPILER_RT_STANDALONE_BUILD)
  set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard to conform to")
  set(CMAKE_CXX_STANDARD_REQUIRED YES)
  set(CMAKE_CXX_EXTENSIONS NO)

  if (NOT LLVM_RUNTIMES_BUILD)
    load_llvm_config()
  endif()
  if (TARGET intrinsics_gen)
    # Loading the llvm config causes this target to be imported so place it
    # under the appropriate folder in an IDE.
    set_target_properties(intrinsics_gen PROPERTIES FOLDER "Compiler-RT Misc")
  endif()

  find_package(Python3 COMPONENTS Interpreter)
  if(NOT Python3_Interpreter_FOUND)
    message(WARNING "Python3 not found, using python2 as a fallback")
    find_package(Python2 COMPONENTS Interpreter REQUIRED)
    if(Python2_VERSION VERSION_LESS 2.7)
      message(SEND_ERROR "Python 2.7 or newer is required")
    endif()

    # Treat python2 as python3
    add_executable(Python3::Interpreter IMPORTED)
    set_target_properties(Python3::Interpreter PROPERTIES
      IMPORTED_LOCATION ${Python2_EXECUTABLE})
    set(Python3_EXECUTABLE ${Python2_EXECUTABLE})
  endif()

  # Ensure that fat libraries are built correctly on Darwin
  if(APPLE)
    include(UseLibtool)
  endif()

  # Define default arguments to lit.
  set(LIT_ARGS_DEFAULT "-sv")
  if (MSVC OR XCODE)
    set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
  endif()
  set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
  set(LLVM_LIT_OUTPUT_DIR "${COMPILER_RT_EXEC_OUTPUT_DIR}")
endif()

construct_compiler_rt_default_triple()
if ("${COMPILER_RT_DEFAULT_TARGET_TRIPLE}" MATCHES ".*hf$")
  if (${COMPILER_RT_DEFAULT_TARGET_ARCH} MATCHES "^arm")
    set(COMPILER_RT_DEFAULT_TARGET_ARCH "armhf")
    CHECK_SYMBOL_EXISTS (__thumb__ "" COMPILER_RT_ARM_THUMB)
  endif()
endif()
if (${COMPILER_RT_DEFAULT_TARGET_ARCH} MATCHES "^mips")
  CHECK_SYMBOL_EXISTS (_MIPS_ARCH_MIPS32R6 "" COMPILER_RT_MIPS32R6)
  CHECK_SYMBOL_EXISTS (_MIPS_ARCH_MIPS64R6 "" COMPILER_RT_MIPS64R6)
  CHECK_SYMBOL_EXISTS (__mips64 "" COMPILER_RT_MIPS_64)
  CHECK_SYMBOL_EXISTS (__MIPSEL__ "" COMPILER_RT_MIPS_EL)
  if ("${COMPILER_RT_MIPS_64}")
    set(COMPILER_RT_DEFAULT_TARGET_ARCH "mips64")
  else()
    set(COMPILER_RT_DEFAULT_TARGET_ARCH "mips")
  endif()
  if ("${COMPILER_RT_MIPS_EL}")
    set(COMPILER_RT_DEFAULT_TARGET_ARCH "${COMPILER_RT_DEFAULT_TARGET_ARCH}el")
  endif()
endif()
if ("${COMPILER_RT_DEFAULT_TARGET_TRIPLE}" MATCHES ".*android.*")
  set(ANDROID 1)
  string(REGEX MATCH "-target(=| +)[^ ]+android[a-z]*([0-9]+)" ANDROID_API_LEVEL "${CMAKE_C_FLAGS}")
  set(ANDROID_API_LEVEL ${CMAKE_MATCH_2})
endif()
pythonize_bool(ANDROID)

set(COMPILER_RT_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
set(COMPILER_RT_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})

pythonize_bool(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR)

# We support running instrumented tests when we're not cross-compiling
# and target a UNIX-like system or Windows.
# We can run tests on Android even when we are cross-compiling.
if((NOT "${CMAKE_CROSSCOMPILING}" AND (UNIX OR WIN32))
   OR ANDROID OR COMPILER_RT_EMULATOR)
  option(COMPILER_RT_CAN_EXECUTE_TESTS "Can we execute instrumented tests" ON)
else()
  option(COMPILER_RT_CAN_EXECUTE_TESTS "Can we execute instrumented tests" OFF)
endif()

option(COMPILER_RT_DEBUG "Build runtimes with full debug info" OFF)
option(COMPILER_RT_EXTERNALIZE_DEBUGINFO
  "Generate dSYM files and strip executables and libraries (Darwin Only)" OFF)
# COMPILER_RT_DEBUG_PYBOOL is used by lit.common.configured.in.
pythonize_bool(COMPILER_RT_DEBUG)

option(COMPILER_RT_INTERCEPT_LIBDISPATCH
  "Support interception of libdispatch (GCD). Requires '-fblocks'" OFF)
option(COMPILER_RT_LIBDISPATCH_INSTALL_PATH
  "Specify if libdispatch is installed in a custom location" "")
if (COMPILER_RT_INTERCEPT_LIBDISPATCH AND NOT APPLE)
  set(COMPILER_RT_LIBDISPATCH_CFLAGS -fblocks)
  set(COMPILER_RT_TEST_LIBDISPATCH_CFLAGS)
  if (COMPILER_RT_LIBDISPATCH_INSTALL_PATH)
    list(APPEND COMPILER_RT_TEST_LIBDISPATCH_CFLAGS
        -I${COMPILER_RT_LIBDISPATCH_INSTALL_PATH}/include
        -L${COMPILER_RT_LIBDISPATCH_INSTALL_PATH}/lib
        -Wl,-rpath=${COMPILER_RT_LIBDISPATCH_INSTALL_PATH}/lib)
  endif()
  list(APPEND COMPILER_RT_TEST_LIBDISPATCH_CFLAGS -lBlocksRuntime -ldispatch)
endif()
if (APPLE) # Always enable on Apple platforms.
  set(COMPILER_RT_INTERCEPT_LIBDISPATCH ON)
endif()
pythonize_bool(COMPILER_RT_INTERCEPT_LIBDISPATCH)

if(APPLE AND SANITIZER_MIN_OSX_VERSION AND SANITIZER_MIN_OSX_VERSION VERSION_LESS "10.9")
  # Mac OS X prior to 10.9 had problems with exporting symbols from
  # libc++/libc++abi.
  set(cxxabi_supported OFF)
else()
  set(cxxabi_supported ON)
endif()

option(SANITIZER_ALLOW_CXXABI "Allow use of C++ ABI details in ubsan" ON)

set(SANITIZER_CAN_USE_CXXABI OFF)
if (cxxabi_supported AND SANITIZER_ALLOW_CXXABI)
  set(SANITIZER_CAN_USE_CXXABI ON)
endif()
pythonize_bool(SANITIZER_CAN_USE_CXXABI)

macro(handle_default_cxx_lib var)
  # Specifying -stdlib= in CMAKE_CXX_FLAGS overrides the defaults.
  if (CMAKE_CXX_FLAGS MATCHES "-stdlib=([a-zA-Z+]*)")
    set(${var}_LIBNAME "${CMAKE_MATCH_1}")
    set(${var}_SYSTEM 1)
  elseif (${var} STREQUAL "default")
    if (APPLE OR CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
      set(${var}_LIBNAME "libc++")
      set(${var}_SYSTEM 1)
    elseif (FUCHSIA)
      set(${var}_LIBNAME "libc++")
      set(${var}_INTREE 1)
    else()
      set(${var}_LIBNAME "libstdc++")
      set(${var}_SYSTEM 1)
    endif()
  else()
    set(${var}_LIBNAME "${${var}}")
    set(${var}_SYSTEM 1)
  endif()
endmacro()

# This is either directly the C++ ABI library or the full C++ library
# which pulls in the ABI transitively.
# TODO: Mark this as internal flag, most users should use COMPILER_RT_CXX_LIBRARY.
set(SANITIZER_CXX_ABI "default" CACHE STRING
    "Specify C++ ABI library to use.")
set(CXXABIS none default libstdc++ libc++ libcxxabi)
set_property(CACHE SANITIZER_CXX_ABI PROPERTY STRINGS ;${CXXABIS})
handle_default_cxx_lib(SANITIZER_CXX_ABI)

# This needs to be a full C++ library for linking gtest and unit tests.
# TODO: Mark this as internal flag, most users should use COMPILER_RT_CXX_LIBRARY.
set(SANITIZER_TEST_CXX "default" CACHE STRING
    "Specify C++ library to use for tests.")
set(CXXLIBS none default libstdc++ libc++)
set_property(CACHE SANITIZER_TEST_CXX PROPERTY STRINGS ;${CXXLIBS})
handle_default_cxx_lib(SANITIZER_TEST_CXX)

option(COMPILER_RT_USE_LLVM_UNWINDER "Use the LLVM unwinder." OFF)
cmake_dependent_option(COMPILER_RT_ENABLE_STATIC_UNWINDER
  "Statically link the LLVM unwinder." OFF
  "COMPILER_RT_USE_LLVM_UNWINDER" OFF)

set(DEFAULT_SANITIZER_USE_STATIC_LLVM_UNWINDER OFF)
if (FUCHSIA)
  set(DEFAULT_SANITIZER_USE_STATIC_LLVM_UNWINDER ON)
elseif (DEFINED LIBUNWIND_ENABLE_SHARED AND NOT LIBUNWIND_ENABLE_SHARED)
  set(DEFAULT_SANITIZER_USE_STATIC_LLVM_UNWINDER ON)
endif()

option(SANITIZER_USE_STATIC_LLVM_UNWINDER
  "Use static LLVM unwinder." ${DEFAULT_SANITIZER_USE_STATIC_LLVM_UNWINDER})
pythonize_bool(SANITIZER_USE_STATIC_LLVM_UNWINDER)

set(DEFAULT_SANITIZER_USE_STATIC_CXX_ABI OFF)
if (DEFINED LIBCXXABI_ENABLE_SHARED AND NOT LIBCXXABI_ENABLE_SHARED)
  set(DEFAULT_SANITIZER_USE_STATIC_CXX_ABI ON)
endif()

option(SANITIZER_USE_STATIC_CXX_ABI
  "Use static libc++abi." ${DEFAULT_SANITIZER_USE_STATIC_CXX_ABI})
pythonize_bool(SANITIZER_USE_STATIC_CXX_ABI)

set(DEFAULT_SANITIZER_USE_STATIC_TEST_CXX OFF)
if (DEFINED LIBCXX_ENABLE_SHARED AND NOT LIBCXX_ENABLE_SHARED)
  set(DEFAULT_SANITIZER_USE_STATIC_TEST_CXX ON)
endif()

option(SANITIZER_USE_STATIC_TEST_CXX
  "Use static libc++ for tests." ${DEFAULT_SANITIZER_USE_STATIC_TEST_CXX})
pythonize_bool(SANITIZER_USE_STATIC_TEST_CXX)

set(COMPILER_RT_SUPPORTED_CXX_LIBRARIES none default libcxx)
set(COMPILER_RT_CXX_LIBRARY "default" CACHE STRING "Specify C++ library to use. Supported values are ${COMPILER_RT_SUPPORTED_CXX_LIBRARIES}.")
if (NOT "${COMPILER_RT_CXX_LIBRARY}" IN_LIST COMPILER_RT_SUPPORTED_CXX_LIBRARIES)
  message(FATAL_ERROR "Unsupported C++ library: '${COMPILER_RT_CXX_LIBRARY}'. Supported values are ${COMPILER_RT_SUPPORTED_CXX_LIBRARIES}.")
endif()
cmake_dependent_option(COMPILER_RT_STATIC_CXX_LIBRARY
  "Statically link the C++ library." OFF
  "COMPILER_RT_CXX_LIBRARY" OFF)

set(DEFAULT_COMPILER_RT_USE_BUILTINS_LIBRARY OFF)
if (FUCHSIA)
  set(DEFAULT_COMPILER_RT_USE_BUILTINS_LIBRARY ON)
endif()

option(COMPILER_RT_USE_BUILTINS_LIBRARY
  "Use compiler-rt builtins instead of libgcc" ${DEFAULT_COMPILER_RT_USE_BUILTINS_LIBRARY})

include(config-ix)

#================================
# Setup Compiler Flags
#================================

# fcf-protection is a gcc/clang option for CET support on Linux platforms.
# We need to handle MSVC CET option on Windows platforms.
if (NOT MSVC)
  if (COMPILER_RT_ENABLE_CET AND NOT COMPILER_RT_HAS_FCF_PROTECTION_FLAG)
    message(FATAL_ERROR "Compiler used to build compiler-rt doesn't support CET!")
  endif()
endif()

if(MSVC)
  # Override any existing /W flags with /W4. This is what LLVM does.  Failing to
  # remove other /W[0-4] flags will result in a warning about overriding a
  # previous flag.
  if (COMPILER_RT_HAS_W4_FLAG)
    string(REGEX REPLACE " /W[0-4]" "" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
    string(REGEX REPLACE " /W[0-4]" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
    append_string_if(COMPILER_RT_HAS_W4_FLAG /W4 CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
  endif()
else()
  append_string_if(COMPILER_RT_HAS_WALL_FLAG -Wall CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif()
if(COMPILER_RT_ENABLE_WERROR)
  append_string_if(COMPILER_RT_HAS_WERROR_FLAG -Werror CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
  append_string_if(COMPILER_RT_HAS_WX_FLAG /WX CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
endif()

# Emulate C99 and C++11's __func__ for MSVC prior to 2013 CTP.
if(NOT COMPILER_RT_HAS_FUNC_SYMBOL)
  add_definitions(-D__func__=__FUNCTION__)
endif()

# Provide some common commandline flags for Sanitizer runtimes.
if("${ANDROID_API_LEVEL}" GREATER_EQUAL 29)
  list(APPEND SANITIZER_COMMON_CFLAGS -fno-emulated-tls)
  string(APPEND COMPILER_RT_TEST_COMPILER_CFLAGS " -fno-emulated-tls")
endif()
if(NOT WIN32)
  append_list_if(COMPILER_RT_HAS_FPIC_FLAG -fPIC SANITIZER_COMMON_CFLAGS)
endif()
append_list_if(COMPILER_RT_HAS_FNO_BUILTIN_FLAG -fno-builtin SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_FNO_EXCEPTIONS_FLAG -fno-exceptions SANITIZER_COMMON_CFLAGS)
if(NOT COMPILER_RT_DEBUG AND NOT APPLE)
  append_list_if(COMPILER_RT_HAS_FOMIT_FRAME_POINTER_FLAG -fomit-frame-pointer SANITIZER_COMMON_CFLAGS)
endif()
append_list_if(COMPILER_RT_HAS_FUNWIND_TABLES_FLAG -funwind-tables SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_FNO_STACK_PROTECTOR_FLAG -fno-stack-protector SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_FNO_SANITIZE_SAFE_STACK_FLAG -fno-sanitize=safe-stack SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_FVISIBILITY_HIDDEN_FLAG -fvisibility=hidden SANITIZER_COMMON_CFLAGS)
if(NOT COMPILER_RT_HAS_FVISIBILITY_HIDDEN_FLAG)
  append_list_if(COMPILER_RT_HAS_FVISIBILITY_INLINES_HIDDEN_FLAG -fvisibility-inlines-hidden SANITIZER_COMMON_CFLAGS)
endif()
append_list_if(COMPILER_RT_HAS_FNO_LTO_FLAG -fno-lto SANITIZER_COMMON_CFLAGS)

# By default do not instrument or use profdata for compiler-rt.
if(NOT COMPILER_RT_ENABLE_PGO)
  if(LLVM_PROFDATA_FILE AND COMPILER_RT_HAS_FNO_PROFILE_INSTR_USE_FLAG)
    list(APPEND SANITIZER_COMMON_CFLAGS "-fno-profile-instr-use")
  endif()
  if(LLVM_BUILD_INSTRUMENTED MATCHES IR AND COMPILER_RT_HAS_FNO_PROFILE_GENERATE_FLAG)
    list(APPEND SANITIZER_COMMON_CFLAGS "-fno-profile-generate")
  elseif((LLVM_BUILD_INSTRUMENTED OR LLVM_BUILD_INSTRUMENTED_COVERAGE) AND COMPILER_RT_HAS_FNO_PROFILE_INSTR_GENERATE_FLAG)
    list(APPEND SANITIZER_COMMON_CFLAGS "-fno-profile-instr-generate")
    if(LLVM_BUILD_INSTRUMENTED_COVERAGE AND COMPILER_RT_HAS_FNO_COVERAGE_MAPPING_FLAG)
      list(APPEND SANITIZER_COMMON_CFLAGS "-fno-coverage-mapping")
    endif()
  endif()
endif()

# The following is a workaround for powerpc64le. This is the only architecture
# that requires -fno-function-sections to work properly. If lacking, the ASan
# Linux test function-sections-are-bad.cpp fails with the following error:
# 'undefined symbol: __sanitizer_unaligned_load32'.
if(DEFINED TARGET_powerpc64le_CFLAGS)
  if(CMAKE_CXX_COMPILER_ID MATCHES "XL")
    append("-qnofuncsect" TARGET_powerpc64le_CFLAGS)
  else()
    append_list_if(COMPILER_RT_HAS_FNO_FUNCTION_SECTIONS_FLAG -fno-function-sections TARGET_powerpc64le_CFLAGS)
  endif()
endif()

# The following is a workaround for s390x.  This avoids creation of "partial
# inline" function fragments when building the asan libraries with certain
# GCC versions.  The presence of those fragments, in particular for the
# interceptors, changes backtraces seen in asan error cases, which causes
# testsuite failures.
if("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "s390x")
  append_list_if(COMPILER_RT_HAS_FNO_PARTIAL_INLINING_FLAG -fno-partial-inlining SANITIZER_COMMON_CFLAGS)
endif()

if(MSVC)
  # Replace the /M[DT][d] flags with /MT, and strip any definitions of _DEBUG,
  # which cause definition mismatches at link time.
  # FIXME: In fact, sanitizers should support both /MT and /MD, see PR20214.
  if(COMPILER_RT_HAS_MT_FLAG)
    foreach(flag_var
      CMAKE_C_FLAGS CMAKE_C_FLAGS_DEBUG CMAKE_C_FLAGS_RELEASE
      CMAKE_C_FLAGS_MINSIZEREL CMAKE_C_FLAGS_RELWITHDEBINFO
      CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG CMAKE_CXX_FLAGS_RELEASE
      CMAKE_CXX_FLAGS_MINSIZEREL CMAKE_CXX_FLAGS_RELWITHDEBINFO)
      string(REGEX REPLACE "/M[DT]d" "/MT" ${flag_var} "${${flag_var}}")
      string(REGEX REPLACE "/MD" "/MT" ${flag_var} "${${flag_var}}")
      string(REGEX REPLACE "/D_DEBUG" "" ${flag_var} "${${flag_var}}")
    endforeach()
  endif()
  append_list_if(COMPILER_RT_HAS_Oy_FLAG /Oy- SANITIZER_COMMON_CFLAGS)
  append_list_if(COMPILER_RT_HAS_GS_FLAG /GS- SANITIZER_COMMON_CFLAGS)

  # Disable thread safe initialization for static locals. ASan shouldn't need
  # it. Thread safe initialization assumes that the CRT has already been
  # initialized, but ASan initializes before the CRT.
  list(APPEND SANITIZER_COMMON_CFLAGS /Zc:threadSafeInit-)
endif()

append_list_if(COMPILER_RT_DEBUG -DSANITIZER_DEBUG=1 SANITIZER_COMMON_CFLAGS)

append_list_if(COMPILER_RT_HAS_WTHREAD_SAFETY_FLAG -Wthread-safety THREAD_SAFETY_FLAGS)
append_list_if(COMPILER_RT_HAS_WTHREAD_SAFETY_REFERENCE_FLAG -Wthread-safety-reference THREAD_SAFETY_FLAGS)
append_list_if(COMPILER_RT_HAS_WTHREAD_SAFETY_BETA_FLAG -Wthread-safety-beta THREAD_SAFETY_FLAGS)
list(APPEND SANITIZER_COMMON_CFLAGS ${THREAD_SAFETY_FLAGS})
string(REPLACE ";" " " thread_safety_flags_space_sep "${THREAD_SAFETY_FLAGS}")
string(APPEND COMPILER_RT_TEST_COMPILER_CFLAGS " ${thread_safety_flags_space_sep}")

# If we're using MSVC,
# always respect the optimization flags set by CMAKE_BUILD_TYPE instead.
if (NOT MSVC)

  # Build with optimization, unless we're in debug mode.
  if(COMPILER_RT_DEBUG)
    list(APPEND SANITIZER_COMMON_CFLAGS -O1)
  else()
    list(APPEND SANITIZER_COMMON_CFLAGS -O3)
  endif()
endif()

# Determine if we should restrict stack frame sizes.
# Stack frames on PowerPC, Mips, SystemZ and in debug build can be much larger than
# anticipated.
# FIXME: Fix all sanitizers and add -Wframe-larger-than to
# SANITIZER_COMMON_FLAGS
if(COMPILER_RT_HAS_WFRAME_LARGER_THAN_FLAG AND NOT COMPILER_RT_DEBUG
   AND NOT ${COMPILER_RT_DEFAULT_TARGET_ARCH} MATCHES "powerpc|mips|s390x")
  set(SANITIZER_LIMIT_FRAME_SIZE TRUE)
else()
  set(SANITIZER_LIMIT_FRAME_SIZE FALSE)
endif()

if(FUCHSIA OR UNIX)
  set(SANITIZER_USE_SYMBOLS TRUE)
else()
  set(SANITIZER_USE_SYMBOLS FALSE)
endif()

# Build sanitizer runtimes with debug info.
if(MSVC)
  # Use /Z7 instead of /Zi for the asan runtime. This avoids the LNK4099
  # warning from the MS linker complaining that it can't find the 'vc140.pdb'
  # file used by our object library compilations.
  list(APPEND SANITIZER_COMMON_CFLAGS /Z7)
  foreach(var_to_update
    CMAKE_CXX_FLAGS
    CMAKE_CXX_FLAGS_DEBUG
    CMAKE_CXX_FLAGS_RELWITHDEBINFO)
    string(REGEX REPLACE "(^| )/Z[i7I]($| )" " /Z7 "
           "${var_to_update}" "${${var_to_update}}")
  endforeach()
elseif(APPLE)
  # On Apple platforms use full debug info (i.e. not `-gline-tables-only`)
  # for all build types so that the runtime can be debugged.
  if(NOT COMPILER_RT_HAS_G_FLAG)
    message(FATAL_ERROR "-g is not supported by host compiler")
  endif()
  list(APPEND SANITIZER_COMMON_CFLAGS -g)
elseif(COMPILER_RT_HAS_GLINE_TABLES_ONLY_FLAG AND NOT COMPILER_RT_DEBUG)
  list(APPEND SANITIZER_COMMON_CFLAGS -gline-tables-only)
elseif(COMPILER_RT_HAS_G_FLAG)
  list(APPEND SANITIZER_COMMON_CFLAGS -g)
endif()

if(LLVM_ENABLE_MODULES)
  # Sanitizers cannot be built with -fmodules. The interceptors intentionally
  # don't include system headers, which is incompatible with modules.
  list(APPEND SANITIZER_COMMON_CFLAGS -fno-modules)
endif()

# Turn off several warnings.
append_list_if(COMPILER_RT_HAS_WGNU_FLAG -Wno-gnu SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_WVARIADIC_MACROS_FLAG -Wno-variadic-macros SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_WC99_EXTENSIONS_FLAG -Wno-c99-extensions SANITIZER_COMMON_CFLAGS)
# format-pedantic warns about passing T* for %p, which is not useful.
append_list_if(COMPILER_RT_HAS_WD4146_FLAG /wd4146 SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_WD4291_FLAG /wd4291 SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_WD4391_FLAG /wd4391 SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_WD4722_FLAG /wd4722 SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_WD4800_FLAG /wd4800 SANITIZER_COMMON_CFLAGS)

append_list_if(MINGW -fms-extensions SANITIZER_COMMON_CFLAGS)

# When lsan scans the stack for detecting reachable pointers, it's possible for
# a leaked pointer, which was pushed to the stack on an earlier function call,
# to still exist on the stack when doing a leak check if that part of the stack
# was not overwritten. In particular, if there's any uninitialized data in the
# lsan runtime, and the SP we start from is sufficiently deep into the runtime,
# then a leaked pointer could be marked as reachable. Such instances could be
# mitigated by clobbering any uninitialized data. Note that this won't cover
# all possible uninitialized stack contents, such as those used for register
# spill slots, unused portions for alignment, or even local variables not
# yet in scope at a certain point in the function.
#
# Note that this type of issue was discovered with lsan, but can apply to other
# sanitizers.
append_list_if(COMPILER_RT_HAS_TRIVIAL_AUTO_INIT -ftrivial-auto-var-init=pattern SANITIZER_COMMON_CFLAGS)

# Set common link flags.
# TODO: We should consider using the same model as libc++, that is use either
# -nostdlib++ and --unwindlib=none if supported, or -nodefaultlibs otherwise.
append_list_if(C_SUPPORTS_NODEFAULTLIBS_FLAG -nodefaultlibs SANITIZER_COMMON_LINK_FLAGS)
append_list_if(COMPILER_RT_HAS_Z_TEXT -Wl,-z,text SANITIZER_COMMON_LINK_FLAGS)

# Only necessary for 32-bit SPARC.  Solaris 11.2+ ld uses -z ignore/-z record
# natively, but supports --as-needed/--no-as-needed for GNU ld compatibility.
if("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "sparc")
  list(APPEND SANITIZER_COMMON_LINK_LIBS -Wl,--as-needed atomic -Wl,--no-as-needed)
endif()

if (COMPILER_RT_USE_BUILTINS_LIBRARY)
  string(REPLACE "-Wl,-z,defs" "" CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS}")
else()
  if (ANDROID)
    append_list_if(COMPILER_RT_HAS_GCC_LIB gcc SANITIZER_COMMON_LINK_LIBS)
  else()
    append_list_if(COMPILER_RT_HAS_GCC_S_LIB gcc_s SANITIZER_COMMON_LINK_LIBS)
  endif()
endif()

append_list_if(COMPILER_RT_HAS_LIBC c SANITIZER_COMMON_LINK_LIBS)
if("${CMAKE_SYSTEM_NAME}" STREQUAL "Fuchsia")
  list(APPEND SANITIZER_COMMON_LINK_LIBS zircon)
endif()

if("${CMAKE_SYSTEM_NAME}" STREQUAL "Fuchsia")
  set(SANITIZER_NO_UNDEFINED_SYMBOLS_DEFAULT ON)
else()
  set(SANITIZER_NO_UNDEFINED_SYMBOLS_DEFAULT OFF)
endif()
option(SANITIZER_NO_UNDEFINED_SYMBOLS "Report error on unresolved symbol references" ${SANITIZER_NO_UNDEFINED_SYMBOLS_DEFAULT})
if (SANITIZER_NO_UNDEFINED_SYMBOLS)
  list(APPEND SANITIZER_COMMON_LINK_FLAGS -Wl,-z,defs)
endif()

# TODO: COMPILER_RT_COMMON_CFLAGS and COMPILER_RT_COMMON_LINK_FLAGS are
# intended for use in non-sanitizer runtimes such as libFuzzer, profile or XRay,
# move these higher to include common flags, then derive SANITIZER_COMMON_CFLAGS
# and SANITIZER_COMMON_LINK_FLAGS from those and append sanitizer-specific flags.
set(COMPILER_RT_COMMON_CFLAGS ${SANITIZER_COMMON_CFLAGS})
set(COMPILER_RT_COMMON_LINK_FLAGS ${SANITIZER_COMMON_LINK_FLAGS})

# We don't use the C++ standard library, so avoid including it by mistake.
append_list_if(COMPILER_RT_HAS_NOSTDINCXX_FLAG -nostdinc++ SANITIZER_COMMON_CFLAGS)
append_list_if(COMPILER_RT_HAS_NOSTDLIBXX_FLAG -nostdlib++ SANITIZER_COMMON_LINK_FLAGS)

# Remove -stdlib= which is unused when passing -nostdinc++...
string(REGEX MATCHALL "-stdlib=[a-zA-Z+]*" stdlib_flag "${CMAKE_CXX_FLAGS}")
string(REGEX REPLACE "-stdlib=[a-zA-Z+]*" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")

# ...we need it to build some runtimes and tests so readd it where appropriate.
list(APPEND COMPILER_RT_COMMON_CFLAGS ${stdlib_flag})
list(APPEND COMPILER_RT_COMMON_LINK_FLAGS ${stdlib_flag})

# TODO: There's a lot of duplication across lib/*/tests/CMakeLists.txt files,
# move some of the common flags to COMPILER_RT_UNITTEST_CFLAGS.

# Unittests need access to C++ standard library.
string(APPEND COMPILER_RT_TEST_COMPILER_CFLAGS " ${stdlib_flag}")

# When cross-compiling, COMPILER_RT_TEST_COMPILER_CFLAGS help in compilation
# and linking of unittests.
string(REPLACE " " ";" COMPILER_RT_UNITTEST_CFLAGS "${COMPILER_RT_TEST_COMPILER_CFLAGS}")
set(COMPILER_RT_UNITTEST_LINK_FLAGS ${COMPILER_RT_UNITTEST_CFLAGS})

if(COMPILER_RT_USE_LLVM_UNWINDER)
  # We're linking directly against the libunwind that we're building so don't
  # try to link in the toolchain's default libunwind which may be missing.
  append_list_if(CXX_SUPPORTS_UNWINDLIB_NONE_FLAG --unwindlib=none COMPILER_RT_COMMON_LINK_FLAGS)
  append_list_if(CXX_SUPPORTS_UNWINDLIB_NONE_FLAG --unwindlib=none COMPILER_RT_UNITTEST_LINK_FLAGS)
  if (COMPILER_RT_ENABLE_STATIC_UNWINDER)
    list(APPEND COMPILER_RT_UNWINDER_LINK_LIBS "$<TARGET_LINKER_FILE:unwind_static>")
  else()
    list(APPEND COMPILER_RT_UNWINDER_LINK_LIBS "$<TARGET_LINKER_FILE:$<IF:$<TARGET_EXISTS:unwind_shared>,unwind_shared,unwind_static>>")
  endif()
endif()

if (COMPILER_RT_CXX_LIBRARY STREQUAL "libcxx")
  # We are using the in-tree libc++ so avoid including the default one.
  append_list_if(COMPILER_RT_HAS_NOSTDINCXX_FLAG -nostdinc++ COMPILER_RT_COMMON_CFLAGS)
  append_list_if(COMPILER_RT_HAS_NOSTDLIBXX_FLAG -nostdlib++ COMPILER_RT_COMMON_LINK_FLAGS)
  # Use the in-tree libc++ through explicit include and library paths.
  set(COMPILER_RT_CXX_CFLAGS "$<$<TARGET_EXISTS:cxx-headers>:$<IF:$<BOOL:${MSVC}>,/imsvc,-isystem>$<JOIN:$<TARGET_PROPERTY:cxx-headers,INTERFACE_INCLUDE_DIRECTORIES>,$<SEMICOLON>$<IF:$<BOOL:${MSVC}>,/imsvc,-isystem>>>")
  if (COMPILER_RT_STATIC_CXX_LIBRARY)
    set(COMPILER_RT_CXX_LINK_LIBS "$<TARGET_LINKER_FILE:cxx_static>")
  else()
    set(COMPILER_RT_CXX_LINK_LIBS "$<TARGET_LINKER_FILE:$<IF:$<TARGET_EXISTS:cxx_shared>,cxx_shared,cxx_static>>")
  endif()
elseif (COMPILER_RT_CXX_LIBRARY STREQUAL "none")
  # We aren't using any C++ standard library so avoid including the default one.
  append_list_if(COMPILER_RT_HAS_NOSTDINCXX_FLAG -nostdinc++ COMPILER_RT_COMMON_CFLAGS)
  append_list_if(COMPILER_RT_HAS_NOSTDLIBXX_FLAG -nostdlib++ COMPILER_RT_COMMON_LINK_FLAGS)
else()
  # Nothing to be done for `default`.
endif()

if (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libc++")
  if (SANITIZER_CXX_ABI_INTREE)
    # TODO: We don't need to add --unwindlib=none to SANITIZER_COMMON_LINK_FLAGS
    # because we added -nodefaultlibs there earlier, and adding would result in
    # a warning, but if we switch to -nostdlib++, we would need to add it here.
    # append_list_if(CXX_SUPPORTS_UNWINDLIB_NONE_FLAG --unwindlib=none SANITIZER_COMMON_LINK_FLAGS)
    if(SANITIZER_USE_STATIC_CXX_ABI)
      if(TARGET libcxx-abi-static)
        set(SANITIZER_CXX_ABI_LIBRARIES libcxx-abi-static)
      endif()
    else()
      if(TARGET libcxx-abi-shared)
        set(SANITIZER_CXX_ABI_LIBRARIES libcxx-abi-shared)
      elseif(TARGET libcxx-abi-static)
        set(SANITIZER_CXX_ABI_LIBRARIES libcxx-abi-static)
      endif()
    endif()
  else()
    append_list_if(COMPILER_RT_HAS_LIBCXX c++ SANITIZER_CXX_ABI_LIBRARIES)
  endif()
elseif (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libcxxabi")
  list(APPEND SANITIZER_CXX_ABI_LIBRARIES "c++abi")
elseif (SANITIZER_CXX_ABI_LIBNAME STREQUAL "libstdc++")
  append_list_if(COMPILER_RT_HAS_LIBSTDCXX stdc++ SANITIZER_CXX_ABI_LIBRARIES)
endif()

if (SANITIZER_TEST_CXX_LIBNAME STREQUAL "libc++")
  if (SANITIZER_TEST_CXX_INTREE)
    list(APPEND SANITIZER_TEST_CXX_CFLAGS "$<$<TARGET_EXISTS:cxx-headers>:$<IF:$<BOOL:${MSVC}>,/imsvc,-isystem>$<JOIN:$<TARGET_PROPERTY:cxx-headers,INTERFACE_INCLUDE_DIRECTORIES>,$<SEMICOLON>$<IF:$<BOOL:${MSVC}>,/imsvc,-isystem>>>")
    if (SANITIZER_USE_STATIC_TEST_CXX)
      list(APPEND SANITIZER_TEST_CXX_LIBRARIES "$<TARGET_LINKER_FILE:cxx_static>")
    else()
      list(APPEND SANITIZER_TEST_CXX_LIBRARIES "$<TARGET_LINKER_FILE:$<IF:$<TARGET_EXISTS:cxx_shared>,cxx_shared,cxx_static>>")
    endif()
    # We are using the in tree libc++ so avoid including the default one.
    append_list_if(COMPILER_RT_HAS_NOSTDINCXX_FLAG -nostdinc++ COMPILER_RT_UNITTEST_CFLAGS)
    append_list_if(COMPILER_RT_HAS_NOSTDLIBXX_FLAG -nostdlib++ COMPILER_RT_UNITTEST_LINK_FLAGS)
  else()
    append_list_if(COMPILER_RT_HAS_LIBCXX -lc++ SANITIZER_TEST_CXX_LIBRARIES)
  endif()
elseif (SANITIZER_TEST_CXX_LIBNAME STREQUAL "libstdc++")
  append_list_if(COMPILER_RT_HAS_LIBSTDCXX -lstdc++ SANITIZER_TEST_CXX_LIBRARIES)
endif()

# Unittests support.
# FIXME: When compiler-rt is build using -DLLVM_BUILD_EXTERNAL_COMPILER_RT=ON, then
# The LLVM_THIRD_PARTY_DIR variable is not set.
if (NOT LLVM_THIRD_PARTY_DIR)
  set(LLVM_THIRD_PARTY_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../third-party")
endif()

set(COMPILER_RT_GTEST_PATH ${LLVM_THIRD_PARTY_DIR}/unittest/googletest)
set(COMPILER_RT_GTEST_SOURCE ${COMPILER_RT_GTEST_PATH}/src/gtest-all.cc)
set(COMPILER_RT_GTEST_CFLAGS
  -DGTEST_NO_LLVM_SUPPORT=1
  -DGTEST_HAS_RTTI=0
  -I${COMPILER_RT_GTEST_PATH}/include
  -I${COMPILER_RT_GTEST_PATH}
)

# Mocking support.
set(COMPILER_RT_GMOCK_PATH ${LLVM_THIRD_PARTY_DIR}/unittest/googlemock)
set(COMPILER_RT_GMOCK_SOURCE ${COMPILER_RT_GMOCK_PATH}/src/gmock-all.cc)
set(COMPILER_RT_GMOCK_CFLAGS
  -DGTEST_NO_LLVM_SUPPORT=1
  -DGTEST_HAS_RTTI=0
  -I${COMPILER_RT_GMOCK_PATH}/include
  -I${COMPILER_RT_GMOCK_PATH}
)

if(COMPILER_RT_HAS_G_FLAG)
  list(APPEND COMPILER_RT_UNITTEST_CFLAGS -g)
endif()
append_list_if(COMPILER_RT_DEBUG -DSANITIZER_DEBUG=1 COMPILER_RT_UNITTEST_CFLAGS)
append_list_if(COMPILER_RT_HAS_WCOVERED_SWITCH_DEFAULT_FLAG -Wno-covered-switch-default COMPILER_RT_UNITTEST_CFLAGS)
append_list_if(COMPILER_RT_HAS_WSUGGEST_OVERRIDE_FLAG -Wno-suggest-override COMPILER_RT_UNITTEST_CFLAGS)

if(MSVC)
  # gtest use a lot of stuff marked as deprecated on Windows.
  list(APPEND COMPILER_RT_GTEST_CFLAGS -Wno-deprecated-declarations)
endif()

# Warnings to turn off for all libraries, not just sanitizers.
append_string_if(COMPILER_RT_HAS_WUNUSED_PARAMETER_FLAG -Wno-unused-parameter CMAKE_C_FLAGS CMAKE_CXX_FLAGS)

if (CMAKE_LINKER MATCHES "link.exe$")
  # Silence MSVC linker warnings caused by empty object files. The
  # sanitizer libraries intentionally use ifdefs that result in empty
  # files, rather than skipping these files in the build system.
  # Ideally, we would pass this flag only for the libraries that need
  # it, but CMake doesn't seem to have a way to set linker flags for
  # individual static libraries, so we enable the suppression flag for
  # the whole compiler-rt project.
  set(CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} /IGNORE:4221")
endif()

add_subdirectory(include)

option(COMPILER_RT_USE_LIBCXX
  "Enable compiler-rt to use libc++ from the source tree" ON)
if(COMPILER_RT_USE_LIBCXX)
  if(LLVM_ENABLE_PROJECTS_USED)
    # Don't use libcxx if LLVM_ENABLE_PROJECTS does not enable it.
    set(COMPILER_RT_LIBCXX_PATH ${LLVM_EXTERNAL_LIBCXX_SOURCE_DIR})
    set(COMPILER_RT_LIBCXXABI_PATH ${LLVM_EXTERNAL_LIBCXXABI_SOURCE_DIR})
  else()
    foreach(path IN ITEMS ${LLVM_MAIN_SRC_DIR}/projects/libcxx
                          ${LLVM_MAIN_SRC_DIR}/runtimes/libcxx
                          ${LLVM_MAIN_SRC_DIR}/../libcxx
                          ${LLVM_EXTERNAL_LIBCXX_SOURCE_DIR})
      if(IS_DIRECTORY ${path})
        set(COMPILER_RT_LIBCXX_PATH ${path})
        break()
      endif()
    endforeach()
    foreach(path IN ITEMS ${LLVM_MAIN_SRC_DIR}/projects/libcxxabi
                          ${LLVM_MAIN_SRC_DIR}/runtimes/libcxxabi
                          ${LLVM_MAIN_SRC_DIR}/../libcxxabi
                          ${LLVM_EXTERNAL_LIBCXXABI_SOURCE_DIR})
      if(IS_DIRECTORY ${path})
        set(COMPILER_RT_LIBCXXABI_PATH ${path})
        break()
      endif()
    endforeach()
  endif()
endif()

set(COMPILER_RT_LLD_PATH ${LLVM_MAIN_SRC_DIR}/tools/lld)
if(EXISTS ${COMPILER_RT_LLD_PATH}/ AND LLVM_TOOL_LLD_BUILD)
  set(COMPILER_RT_HAS_LLD TRUE)
else()
  set(COMPILER_RT_LLD_PATH ${LLVM_MAIN_SRC_DIR}/../lld)
  if(EXISTS ${COMPILER_RT_LLD_PATH}/ AND LLVM_TOOL_LLD_BUILD)
    set(COMPILER_RT_HAS_LLD TRUE)
  endif()
endif()

if(ANDROID)
  set(COMPILER_RT_HAS_LLD TRUE)
  set(COMPILER_RT_TEST_USE_LLD TRUE)
  append_list_if(COMPILER_RT_HAS_FUSE_LD_LLD_FLAG -fuse-ld=lld SANITIZER_COMMON_LINK_FLAGS)
  append_list_if(COMPILER_RT_HAS_LLD -fuse-ld=lld COMPILER_RT_UNITTEST_LINK_FLAGS)
endif()
pythonize_bool(COMPILER_RT_HAS_LLD)
pythonize_bool(COMPILER_RT_TEST_USE_LLD)

add_subdirectory(lib)

if(COMPILER_RT_INCLUDE_TESTS)
  add_subdirectory(unittests)
  add_subdirectory(test)
  # Don't build llvm-lit for runtimes-build, it will clean up map_config.
  if (COMPILER_RT_STANDALONE_BUILD AND NOT LLVM_RUNTIMES_BUILD)
    # If we have a valid source tree, generate llvm-lit into the bin directory.
    # The user can still choose to have the check targets *use* a different lit
    # by specifying -DLLVM_EXTERNAL_LIT, but we generate it regardless.
    if (EXISTS ${LLVM_MAIN_SRC_DIR}/utils/llvm-lit)
      # Needed for lit support in standalone builds.
      include(AddLLVM)
      add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/llvm-lit ${CMAKE_CURRENT_BINARY_DIR}/llvm-lit)
    elseif(NOT EXISTS ${LLVM_EXTERNAL_LIT})
      message(WARNING "Could not find LLVM source directory and LLVM_EXTERNAL_LIT does not"
                       "point to a valid file.  You will not be able to run tests.")
    endif()
  endif()
endif()

add_subdirectory(tools)