[CMake] Split the target side of runtimes build

[phosek]

Summary

Previously, llvm/runtimes/CMakeLists.txt played two different roles:

1. host side which could used to set up the build of runtimes for different targets in the right order;
2. target side to build the runtimes for the specified target.

This change splits llvm/runtimes/CMakeLists.txt and moves the target
side to runtimes/CMakeLists laying down the foundation for the "A vision
for building the runtimes" proposal. From the user perspective, there
shouldn't be any visible difference at the moment.

[smeenai]

LGTM.

I'm a huge fan of this. I had to always spend time figuring out if the code I was reading in the old file was for the host or the target build; having them separated makes things much more understandable IMO.

llvm/runtimes/CMakeLists.txt

1–10

Nit: "a Clang toolchain" or "the Clang toolchain" sounds more gramatically correct to me.

[ldionne]

Oh, I missed this review, but thanks a lot for making this change!!

[kaz7]

I am looking at codes around this and have noticed this glitch. Others like $(name)_extra_args are initialized with set(${name}_extra_args ${ARG_CMAKE_ARGS}).

llvm/runtimes/CMakeLists.txt

111–112

Don't we need set(${target}_extra_args ${ARG_CMAKE_ARGS}) here to initialize $(target)_extra_args?

llvm/runtimes/CMakeLists.txt

-# This file handles building LLVM runtime sub-projects.
-
-# Runtimes are different from tools or other drop-in projects because runtimes
-# should be built with the LLVM toolchain from the build directory. This file is
-# a first step to formalizing runtime build interfaces.
-
-# Setting CMake minimum required version should be at the very top of the file
-# if this is the entry point.
-if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-  cmake_minimum_required(VERSION 3.13.4)
-  project(Runtimes C CXX ASM)
-endif()
-
-# Find all subdirectories containing CMake projects
-file(GLOB entries *)
-foreach(entry ${entries})
-  if(IS_DIRECTORY ${entry} AND EXISTS ${entry}/CMakeLists.txt)
-    list(APPEND runtimes ${entry})
-  endif()
-endforeach()
-
-# Side-by-side subprojects layout.
-set(LLVM_ALL_RUNTIMES "libcxx;libcxxabi;libunwind;compiler-rt;openmp")
+# TODO: This file assumes the Clang toolchain so it'd be better if it lived in
+# Clang, except there already is clang/runtime directory which contains
+# similar although simpler functionality. We should figure out how to merge
+# the two files.
+
+# TODO: Selecting runtimes should be always performed inside the runtimes
+# build, see runtimes/CMakeLists.txt, except that we currently check whether
+# compiler-rt is being built to determine whether to first build builtins
+# or not so we need that information in this file as well.
+set(LLVM_ALL_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind;openmp")
 set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
   "Semicolon-separated list of runtimes to build (${LLVM_ALL_RUNTIMES}), or \"all\".")
 if(LLVM_ENABLE_RUNTIMES STREQUAL "all" )
   set(LLVM_ENABLE_RUNTIMES ${LLVM_ALL_RUNTIMES})
 endif()
 foreach(proj ${LLVM_ENABLE_RUNTIMES})
   set(proj_dir "${CMAKE_CURRENT_SOURCE_DIR}/../../${proj}")
   if(IS_DIRECTORY ${proj_dir} AND EXISTS ${proj_dir}/CMakeLists.txt)
foreach(entry ${runtimes})
     get_filename_component(projName ${entry} NAME)
     if("${projName}" MATCHES "compiler-rt")
       set(${path} ${entry} PARENT_SCOPE)
       return()
     endif()
   endforeach()
 endfunction()
 
-# If this file is acting as a top-level CMake invocation, this code path is
-# triggered by the external project call for the runtimes target below.
-if(${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
-
-  function(runtime_register_component name)
-    set_property(GLOBAL APPEND PROPERTY SUB_COMPONENTS ${name})
-  endfunction()
-
-  cmake_minimum_required(VERSION 3.13.4)
-  project(Runtimes C CXX ASM)
-
-  find_package(LLVM PATHS "${LLVM_BINARY_DIR}" NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
-  find_package(Clang PATHS "${LLVM_BINARY_DIR}" NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
-
-  # Add the root project's CMake modules, and the LLVM build's modules to the
-  # CMake module path.
-  list(INSERT CMAKE_MODULE_PATH 0
-    "${CMAKE_CURRENT_SOURCE_DIR}/../cmake"
-    "${CMAKE_CURRENT_SOURCE_DIR}/../cmake/modules"
-  )
-
-  # Some of the runtimes will conditionally use the compiler-rt sanitizers
-  # to make this work smoothly we ensure that compiler-rt is added first in
-  # the list of sub-projects. This allows other sub-projects to have checks
-  # like `if(TARGET asan)` to enable building with asan.
-  get_compiler_rt_path(compiler_rt_path)
-  if(compiler_rt_path)
-    list(REMOVE_ITEM runtimes ${compiler_rt_path})
-    if(NOT DEFINED LLVM_BUILD_COMPILER_RT OR LLVM_BUILD_COMPILER_RT)
-      list(INSERT runtimes 0 ${compiler_rt_path})
-    endif()
-  endif()
-
-  # Setting these variables will allow the sub-build to put their outputs into
-  # the library and bin directories of the top-level build.
-  set(LLVM_LIBRARY_OUTPUT_INTDIR ${LLVM_LIBRARY_DIR})
-  set(LLVM_RUNTIME_OUTPUT_INTDIR ${LLVM_TOOLS_BINARY_DIR})
-
-  # This variable makes sure that e.g. llvm-lit is found.
-  set(LLVM_MAIN_SRC_DIR ${LLVM_BUILD_MAIN_SRC_DIR})
-  set(LLVM_CMAKE_PATH ${LLVM_MAIN_SRC_DIR}/cmake/modules)
-
-  # This variable is used by individual runtimes to locate LLVM files.
-  set(LLVM_PATH ${LLVM_BUILD_MAIN_SRC_DIR})
-
-  if(APPLE)
-    set(LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
-  endif()
-
-  include(CheckLibraryExists)
-  include(CheckCCompilerFlag)
-
-  # We don't have libc++ (yet)...
-  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdinc++ -nostdlib++")
-
-  # ...but we need access to libc++ headers for CMake checks to succeed.
-  if (LLVM_EXTERNAL_LIBCXX_SOURCE_DIR AND "libcxx" IN_LIST LLVM_ENABLE_RUNTIMES)
-    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -isystem ${LLVM_EXTERNAL_LIBCXX_SOURCE_DIR}/include")
-  endif()
-
-  # Avoid checking whether the compiler is working.
-  set(LLVM_COMPILER_CHECKED ON)
-
-  # Handle common options used by all runtimes.
-  include(AddLLVM)
-  include(HandleLLVMOptions)
-  include(FindPythonInterp)
-
-  # Remove the -nostdlib++ option we've added earlier.
-  string(REPLACE "-nostdlib++" "" CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
-
-  # Use libtool instead of ar if you are both on an Apple host, and targeting Apple.
-  if(CMAKE_HOST_APPLE AND APPLE)
-    include(UseLibtool)
-  endif()
-
-  # This can be used to detect whether we're in the runtimes build.
-  set(RUNTIMES_BUILD ON)
-
-  foreach(entry ${runtimes})
-    get_filename_component(projName ${entry} NAME)
-
-    # TODO: Clean this up as part of an interface standardization
-    string(REPLACE "-" "_" canon_name ${projName})
-    string(TOUPPER ${canon_name} canon_name)
-
-    # The subdirectories need to treat this as standalone builds. D57992 tried
-    # to get rid of this, but the runtimes treat *_STANDALONE_BUILD=OFF as if
-    # llvm & clang are configured in the same CMake, and setup dependencies
-    # against their targets. OpenMP has fixed the issue so we don't set the
-    # variable.
-    if (NOT ${canon_name} STREQUAL "OPENMP")
-      set(${canon_name}_STANDALONE_BUILD ON)
-    endif()
-
-    if(LLVM_RUNTIMES_LIBDIR_SUBDIR)
-      set(${canon_name}_LIBDIR_SUBDIR "${LLVM_RUNTIMES_LIBDIR_SUBDIR}" CACHE STRING "" FORCE)
-    endif()
-
-    # Setting a variable to let sub-projects detect which other projects
-    # will be included under here.
-    set(HAVE_${canon_name} ON)
-  endforeach()
-
-  # We do this in two loops so that HAVE_* is set for each runtime before the
-  # other runtimes are added.
-  foreach(entry ${runtimes})
-    get_filename_component(projName ${entry} NAME)
-
-    # Between each sub-project we want to cache and clear the LIT properties
-    set_property(GLOBAL PROPERTY LLVM_LIT_TESTSUITES)
-    set_property(GLOBAL PROPERTY LLVM_LIT_PARAMS)
-    set_property(GLOBAL PROPERTY LLVM_LIT_DEPENDS)
-    set_property(GLOBAL PROPERTY LLVM_LIT_EXTRA_ARGS)
-
-    add_subdirectory(${entry} ${projName})
-
-    get_property(LLVM_LIT_TESTSUITES GLOBAL PROPERTY LLVM_LIT_TESTSUITES)
-    get_property(LLVM_LIT_PARAMS GLOBAL PROPERTY LLVM_LIT_PARAMS)
-    get_property(LLVM_LIT_DEPENDS GLOBAL PROPERTY LLVM_LIT_DEPENDS)
-    get_property(LLVM_LIT_EXTRA_ARGS GLOBAL PROPERTY LLVM_LIT_EXTRA_ARGS)
-
-    list(APPEND RUNTIMES_LIT_TESTSUITES ${LLVM_LIT_TESTSUITES})
-    list(APPEND RUNTIMES_LIT_PARAMS ${LLVM_LIT_PARAMS})
-    list(APPEND RUNTIMES_LIT_DEPENDS ${LLVM_LIT_DEPENDS})
-    list(APPEND RUNTIMES_LIT_EXTRA_ARGS ${LLVM_LIT_EXTRA_ARGS})
-  endforeach()
-
-  if(LLVM_INCLUDE_TESTS)
-    # Add a global check rule now that all subdirectories have been traversed
-    # and we know the total set of lit testsuites.
-
-    add_lit_target(check-runtimes
-      "Running all regression tests"
-      ${RUNTIMES_LIT_TESTSUITES}
-      PARAMS ${RUNTIMES_LIT_PARAMS}
-      DEPENDS ${RUNTIMES_LIT_DEPENDS}
-      ARGS ${RUNTIMES_LIT_EXTRA_ARGS}
-      )
-    add_custom_target(runtimes-test-depends DEPENDS ${RUNTIMES_LIT_DEPENDS})
-  endif()
-
-  get_property(SUB_COMPONENTS GLOBAL PROPERTY SUB_COMPONENTS)
-  if(SUB_COMPONENTS)
-    list(REMOVE_DUPLICATES SUB_COMPONENTS)
-    foreach(component ${SUB_COMPONENTS})
-      if(NOT TARGET ${component})
-        message(SEND_ERROR "Missing target for runtime component ${component}!")
-        continue()
-      endif()
-
-      if(TARGET check-${component})
-        list(APPEND SUB_CHECK_TARGETS check-${component})
-      endif()
-
-      if(TARGET install-${component})
-        list(APPEND SUB_INSTALL_TARGETS install-${component})
-      endif()
-      if(TARGET install-${component}-stripped)
-        list(APPEND SUB_INSTALL_TARGETS install-${component}-stripped)
-      endif()
-    endforeach()
-
-    if(LLVM_RUNTIMES_TARGET)
-      configure_file(
-        ${CMAKE_CURRENT_SOURCE_DIR}/Components.cmake.in
-        ${LLVM_BINARY_DIR}/runtimes/${LLVM_RUNTIMES_TARGET}/Components.cmake)
-    else()
-      configure_file(
-        ${CMAKE_CURRENT_SOURCE_DIR}/Components.cmake.in
-        ${LLVM_BINARY_DIR}/runtimes/Components.cmake)
-    endif()
-  endif()
-
-else() # if this is included from LLVM's CMake
-  include(LLVMExternalProjectUtils)
 
-  if(NOT LLVM_BUILD_RUNTIMES)
-    set(EXTRA_ARGS EXCLUDE_FROM_ALL)
-  endif()
 
-  function(check_apple_target triple builtin_or_runtime)
-    set(error "\
 compiler-rt for Darwin builds for all platforms and architectures using a \
 single configuration. Specify only a single darwin triple (e.g. x86_64-apple-darwin) \
 in your targets list (and not a triple for a specific platform such as macos). \
 You can use variables such as COMPILER_RT_ENABLE_IOS and DARWIN_ios_ARCHS to \
 control the specific platforms and architectures to build.")
 
-    set(seen_property ${builtin_or_runtime}_darwin_triple_seen)
-    string(REPLACE "-" ";" triple_components ${triple})
-    foreach(component ${triple_components})
-      string(TOLOWER "${component}" component_lower)
-      if(component_lower MATCHES "^darwin")
-        get_property(darwin_triple_seen GLOBAL PROPERTY ${seen_property})
-        if(darwin_triple_seen)
-          message(FATAL_ERROR "${error}")
-        endif()
-        set_property(GLOBAL PROPERTY ${seen_property} YES)
-        if(NOT RUNTIMES_BUILD_ALLOW_DARWIN)
-          message(FATAL_ERROR "\
 ${error} Set RUNTIMES_BUILD_ALLOW_DARWIN to allow a single darwin triple.")
-        endif()
-      elseif(component_lower MATCHES "^ios|^macos|^tvos|^watchos")
-        message(FATAL_ERROR "${error}")
-      endif()
-    endforeach()
-  endfunction()
 
-  function(builtin_default_target compiler_rt_path)
-    cmake_parse_arguments(ARG "" "" "DEPENDS" ${ARGN})
 
-    set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR_default ON)
-    # AIX should fold 32-bit & 64-bit arch libraries into a single archive.
-    if (TARGET_TRIPLE MATCHES "aix")
-      set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR_default OFF)
-    endif()
 
-    llvm_ExternalProject_Add(builtins
-                             ${compiler_rt_path}/lib/builtins
-                             DEPENDS ${ARG_DEPENDS}
-                             CMAKE_ARGS -DLLVM_LIBRARY_OUTPUT_INTDIR=${LLVM_LIBRARY_DIR}
-                                        -DLLVM_RUNTIME_OUTPUT_INTDIR=${LLVM_TOOLS_BINARY_DIR}
-                                        -DLLVM_DEFAULT_TARGET_TRIPLE=${TARGET_TRIPLE}
-                                        -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=${LLVM_ENABLE_PER_TARGET_RUNTIME_DIR_default}
-                                        -DCMAKE_C_COMPILER_TARGET=${TARGET_TRIPLE}
-                                        -DCMAKE_ASM_COMPILER_TARGET=${TARGET_TRIPLE}
-                                        -DCMAKE_C_COMPILER_WORKS=ON
-                                        -DCMAKE_ASM_COMPILER_WORKS=ON
-                                        ${BUILTINS_CMAKE_ARGS}
-                             PASSTHROUGH_PREFIXES COMPILER_RT
-                             USE_TOOLCHAIN
-                             ${EXTRA_ARGS})
-  endfunction()
 
-  function(builtin_register_target compiler_rt_path target)
-    cmake_parse_arguments(ARG "" "" "DEPENDS" ${ARGN})
 
-    check_apple_target(${target} builtin)
+  # The subdirectories need to treat this as standalone builds. D57992 tried
+  # to get rid of this, but the runtimes treat *_STANDALONE_BUILD=OFF as if
+  # llvm & clang are configured in the same CMake, and setup dependencies
+  # against their targets. OpenMP has fixed the issue so we don't set the
+  # variable.
+  if (NOT ${canon_name} STREQUAL "OPENMP")
+    set(${canon_name}_STANDALONE_BUILD ON)
+  endif()
+
 
-    get_cmake_property(variableNames VARIABLES)
-    foreach(variableName ${variableNames})
-      string(FIND "${variableName}" "BUILTINS_${target}" out)
-      if("${out}" EQUAL 0)
-        string(REPLACE "BUILTINS_${target}_" "" new_name ${variableName})
-        string(REPLACE ";" "|" new_value "${${variableName}}")
-        list(APPEND ${target}_extra_args "-D${new_name}=${new_value}")
-      endif()
-    endforeach()
 
-    llvm_ExternalProject_Add(builtins-${target}
-                             ${compiler_rt_path}/lib/builtins
-                             DEPENDS ${ARG_DEPENDS}
-                             CMAKE_ARGS -DLLVM_LIBRARY_OUTPUT_INTDIR=${LLVM_LIBRARY_DIR}
-                                        -DLLVM_RUNTIME_OUTPUT_INTDIR=${LLVM_TOOLS_BINARY_DIR}
-                                        -DLLVM_DEFAULT_TARGET_TRIPLE=${target}
-                                        -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON
-                                        -DCMAKE_C_COMPILER_TARGET=${target}
-                                        -DCMAKE_ASM_COMPILER_TARGET=${target}
-                                        -DCMAKE_C_COMPILER_WORKS=ON
-                                        -DCMAKE_ASM_COMPILER_WORKS=ON
-                                        -DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON
-                                        ${${target}_extra_args}
-                             USE_TOOLCHAIN
-                             ${EXTRA_ARGS})
-  endfunction()
 
-  # If compiler-rt is present we need to build the builtin libraries first. This
-  # is required because the other runtimes need the builtin libraries present
-  # before the just-built compiler can pass the configuration tests.
-  get_compiler_rt_path(compiler_rt_path)
-  if(compiler_rt_path)
-    if(NOT LLVM_BUILTIN_TARGETS)
-      builtin_default_target(${compiler_rt_path}
-        DEPENDS clang-resource-headers)
-    else()
-      if("default" IN_LIST LLVM_BUILTIN_TARGETS)
-        builtin_default_target(${compiler_rt_path}
-          DEPENDS clang-resource-headers)
-        list(REMOVE_ITEM LLVM_BUILTIN_TARGETS "default")
-      else()
-        add_custom_target(builtins)
-        add_custom_target(install-builtins)
-        add_custom_target(install-builtins-stripped)
-      endif()
 
-      foreach(target ${LLVM_BUILTIN_TARGETS})
-        builtin_register_target(${compiler_rt_path} ${target}
-          DEPENDS clang-resource-headers)
 
-        add_dependencies(builtins builtins-${target})
-        add_dependencies(install-builtins install-builtins-${target})
-        add_dependencies(install-builtins-stripped install-builtins-${target}-stripped)
-      endforeach()
-    endif()
-    set(deps builtins)
-    # We don't need to depend on the builtins if we're building instrumented
-    # because the next stage will use the same compiler used to build this stage.
-    if(NOT LLVM_BUILD_INSTRUMENTED AND CLANG_ENABLE_BOOTSTRAP)
-      add_dependencies(clang-bootstrap-deps builtins)
-    endif()
-  endif()
 
-  # We create a list the names of all the runtime projects in all uppercase and
-  # with dashes turned to underscores. This gives us the CMake variable prefixes
-  # for all variables that will apply to runtimes.
-  foreach(entry ${runtimes})
-    get_filename_component(projName ${entry} NAME)
-    string(REPLACE "-" "_" canon_name ${projName})
-    string(TOUPPER ${canon_name} canon_name)
-    list(APPEND prefixes ${canon_name})
-    if (${canon_name} STREQUAL "OPENMP")
-      list(APPEND prefixes "LIBOMP" "LIBOMPTARGET")
-    endif()
-    # Many compiler-rt options start with SANITIZER_ rather than COMPILER_RT_,
-    # so when compiler-rt is enabled, consider both.
-    if(canon_name STREQUAL "COMPILER_RT")
-      list(APPEND prefixes SANITIZER)
-    endif()
 
-    string(FIND ${projName} "lib" LIB_IDX)
-    if(LIB_IDX EQUAL 0)
-      string(SUBSTRING ${projName} 3 -1 projName)
-    endif()
-    list(APPEND runtime_names ${projName})
-  endforeach()
 
-  if(LLVM_RUNTIME_BUILD_ID_LINK_TARGETS)
-    configure_file(
-      ${CMAKE_CURRENT_SOURCE_DIR}/llvm-strip-link.in
-      ${CMAKE_CURRENT_BINARY_DIR}/llvm-strip-link
-      @ONLY
-    )
-  endif()
 
-  function(runtime_default_target)
-    cmake_parse_arguments(ARG "" "" "DEPENDS;PREFIXES" ${ARGN})
 
-    include(${LLVM_BINARY_DIR}/runtimes/Components.cmake OPTIONAL)
-    set(SUB_CHECK_TARGETS ${SUB_CHECK_TARGETS} PARENT_SCOPE)
-    set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${LLVM_BINARY_DIR}/runtimes/Components.cmake)
 
-    foreach(runtime_name ${runtime_names})
-      list(APPEND extra_targets
-        ${runtime_name}
-        install-${runtime_name}
-        install-${runtime_name}-stripped)
-      if(LLVM_INCLUDE_TESTS)
-        list(APPEND test_targets check-${runtime_name})
-      endif()
-    endforeach()
-    foreach(component ${LLVM_RUNTIME_DISTRIBUTION_COMPONENTS})
-      if(NOT ${component} IN_LIST SUB_COMPONENTS)
-        list(APPEND extra_targets ${component} install-${component} install-${component}-stripped)
-      endif()
-    endforeach()
 
-    if(LLVM_INCLUDE_TESTS)
-      list(APPEND test_targets runtimes-test-depends check-runtimes)
-    endif()
 
-    set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR_default ON)
-    # AIX should fold 32-bit & 64-bit arch libraries into a single archive.
-    if (TARGET_TRIPLE MATCHES "aix")
-      set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR_default OFF)
-    endif()
 
-    llvm_ExternalProject_Add(runtimes
-                             ${CMAKE_CURRENT_SOURCE_DIR}
-                             DEPENDS ${ARG_DEPENDS}
-                             # Builtins were built separately above
-                             CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=Off
-                                        -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
-                                        -DLLVM_DEFAULT_TARGET_TRIPLE=${TARGET_TRIPLE}
-                                        -DLLVM_ENABLE_PROJECTS_USED=${LLVM_ENABLE_PROJECTS_USED}
-                                        -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=${LLVM_ENABLE_PER_TARGET_RUNTIME_DIR_default}
-                                        -DCMAKE_C_COMPILER_TARGET=${TARGET_TRIPLE}
-                                        -DCMAKE_CXX_COMPILER_TARGET=${TARGET_TRIPLE}
-                                        -DCMAKE_ASM_COMPILER_TARGET=${TARGET_TRIPLE}
-                                        -DCMAKE_C_COMPILER_WORKS=ON
-                                        -DCMAKE_CXX_COMPILER_WORKS=ON
-                                        -DCMAKE_ASM_COMPILER_WORKS=ON
-                                        ${RUNTIMES_CMAKE_ARGS}
-                             PASSTHROUGH_PREFIXES LLVM_ENABLE_RUNTIMES
-                                                  ${ARG_PREFIXES}
-                             EXTRA_TARGETS ${extra_targets}
-                                           ${test_targets}
-                                           ${SUB_COMPONENTS}
-                                           ${SUB_CHECK_TARGETS}
-                                           ${SUB_INSTALL_TARGETS}
-                             USE_TOOLCHAIN
-                             ${EXTRA_ARGS})
-  endfunction()
+                           ${CMAKE_CURRENT_SOURCE_DIR}/../../runtimes
 
-  # runtime_register_target(target)
-  #   Utility function to register external runtime target.
-  function(runtime_register_target name target)
-    cmake_parse_arguments(ARG "" "" "DEPENDS;CMAKE_ARGS" ${ARGN})
-    include(${LLVM_BINARY_DIR}/runtimes/${name}/Components.cmake OPTIONAL)
-    set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${LLVM_BINARY_DIR}/runtimes/${name}/Components.cmake)
 
-    check_apple_target(${target} runtime)
 
-    set(${name}_deps ${ARG_DEPENDS})
-    if(NOT name STREQUAL target)
-      list(APPEND ${name}_deps runtimes-${target})
-    endif()
 
-    foreach(runtime_name ${runtime_names})
-      set(${runtime_name}-${name} ${runtime_name})
-      set(install-${runtime_name}-${name} install-${runtime_name})
-      set(install-${runtime_name}-${name}-stripped install-${runtime_name}-stripped)
-      list(APPEND ${name}_extra_targets ${runtime_name}-${name} install-${runtime_name}-${name} install-${runtime_name}-${name}-stripped)
-      if(LLVM_INCLUDE_TESTS)
-        set(check-${runtime_name}-${name} check-${runtime_name} )
-        list(APPEND ${name}_test_targets check-${runtime_name}-${name})
-      endif()
-    endforeach()
 
-    foreach(target_name IN LISTS SUB_COMPONENTS SUB_INSTALL_TARGETS)
-      set(${target_name}-${name} ${target_name})
-      list(APPEND ${name}_extra_targets ${target_name}-${name})
-    endforeach()
 
-    foreach(component ${LLVM_RUNTIME_DISTRIBUTION_COMPONENTS})
-      set(${component}-${name} ${component})
-      set(install-${component}-${name} install-${component})
-      set(install-${component}-${name}-stripped install-${component}-stripped)
-      list(APPEND ${name}_extra_targets ${component}-${name} install-${component}-${name} install-${component}-${name}-stripped)
-    endforeach()
 
-    if(LLVM_INCLUDE_TESTS)
-      set(runtimes-test-depends-${name} runtimes-test-depends)
-      set(check-runtimes-${name} check-runtimes)
-      list(APPEND ${name}_test_targets runtimes-test-depends-${name} check-runtimes-${name})
-      foreach(target_name IN LISTS SUB_CHECK_TARGETS)
-        set(${target_name}-${name} ${target_name})
-        list(APPEND ${name}_test_targets ${target_name}-${name})
-        list(APPEND test_targets ${target_name}-${name})
-      endforeach()
-      set(test_targets "${test_targets}" PARENT_SCOPE)
-    endif()
 
-    set(${name}_extra_args ${ARG_CMAKE_ARGS})
-    get_cmake_property(variableNames VARIABLES)
-    foreach(variableName ${variableNames})
-      string(FIND "${variableName}" "RUNTIMES_${target}_" out)
-      if("${out}" EQUAL 0)
-        string(REPLACE "RUNTIMES_${target}_" "" new_name ${variableName})
-        string(REPLACE ";" "|" new_value "${${variableName}}")
-        list(APPEND ${name}_extra_args "-D${new_name}=${new_value}")
-      endif()
-    endforeach()
-    if(NOT "${name}" STREQUAL "${target}")
-      foreach(variableName ${variableNames})
-        string(FIND "${variableName}" "RUNTIMES_${name}_" out)
-        if("${out}" EQUAL 0)
-          string(REPLACE "RUNTIMES_${name}_" "" new_name ${variableName})
-          string(REPLACE ";" "|" new_value "${${variableName}}")
-          list(APPEND ${name}_extra_args "-D${new_name}=${new_value}")
-        endif()
-      endforeach()
-    endif()
 
-    if(NOT RUNTIMES_${name}_LLVM_ENABLE_RUNTIMES AND NOT RUNTIMES_${target}_LLVM_ENABLE_RUNTIMES)
-      string(REPLACE ";" "|" LLVM_ENABLE_RUNTIMES_PASSTHROUGH "${LLVM_ENABLE_RUNTIMES}")
-      list(APPEND ${name}_extra_args -DLLVM_ENABLE_RUNTIMES=${LLVM_ENABLE_RUNTIMES_PASSTHROUGH})
-    endif()
 
-    if(target IN_LIST LLVM_RUNTIME_BUILD_ID_LINK_TARGETS)
-      list(APPEND EXTRA_ARGS STRIP_TOOL ${CMAKE_CURRENT_BINARY_DIR}/llvm-strip-link)
-    endif()
 
-    llvm_ExternalProject_Add(runtimes-${name}
-                             ${CMAKE_CURRENT_SOURCE_DIR}
-                             DEPENDS ${${name}_deps}
-                             # Builtins were built separately above
-                             CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=Off
-                                        -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
-                                        -DLLVM_DEFAULT_TARGET_TRIPLE=${target}
-                                        -DLLVM_ENABLE_PROJECTS_USED=${LLVM_ENABLE_PROJECTS_USED}
-                                        -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON
-                                        -DCMAKE_C_COMPILER_TARGET=${target}
-                                        -DCMAKE_CXX_COMPILER_TARGET=${target}
-                                        -DCMAKE_ASM_COMPILER_TARGET=${target}
-                                        -DCMAKE_C_COMPILER_WORKS=ON
-                                        -DCMAKE_CXX_COMPILER_WORKS=ON
-                                        -DCMAKE_ASM_COMPILER_WORKS=ON
-                                        -DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON
-                                        -DLLVM_RUNTIMES_TARGET=${name}
-                                        ${${name}_extra_args}
-                             EXTRA_TARGETS ${${name}_extra_targets}
-                                           ${${name}_test_targets}
-                             USE_TOOLCHAIN
-                             ${EXTRA_ARGS})
-  endfunction()
+                           ${CMAKE_CURRENT_SOURCE_DIR}/../../runtimes
 
-  if(runtimes)
-    # Create a runtimes target that uses this file as its top-level CMake file.
-    # The runtimes target is a configuration of all the runtime libraries
-    # together in a single CMake invocaiton.
-    if(NOT LLVM_RUNTIME_TARGETS)
-      runtime_default_target(
-        DEPENDS ${deps}
-        PREFIXES ${prefixes})
-      set(test_targets check-runtimes)
-    else()
-      if("default" IN_LIST LLVM_RUNTIME_TARGETS)
-        runtime_default_target(
-          DEPENDS ${deps}
-          PREFIXES ${prefixes})
-        list(REMOVE_ITEM LLVM_RUNTIME_TARGETS "default")
-      else()
-        add_custom_target(runtimes)
-        add_custom_target(runtimes-configure)
-        add_custom_target(install-runtimes)
-        add_custom_target(install-runtimes-stripped)
-        if(LLVM_INCLUDE_TESTS)
-          add_custom_target(check-runtimes)
-          add_custom_target(runtimes-test-depends)
-          set(test_targets "")
-        endif()
-        foreach(runtime_name ${runtime_names})
-          add_custom_target(${runtime_name})
-          add_custom_target(install-${runtime_name})
-          add_custom_target(install-${runtime_name}-stripped)
-        endforeach()
-        if(LLVM_RUNTIME_DISTRIBUTION_COMPONENTS)
-          foreach(component ${LLVM_RUNTIME_DISTRIBUTION_COMPONENTS})
-            add_custom_target(${component})
-            add_custom_target(install-${component})
-            add_custom_target(install-${component}-stripped)
-          endforeach()
-        endif()
-      endif()
 
-      foreach(name ${LLVM_RUNTIME_TARGETS})
-        runtime_register_target(${name} ${name}
-          DEPENDS ${deps})
 
-        add_dependencies(runtimes runtimes-${name})
-        add_dependencies(runtimes-configure runtimes-${name}-configure)
-        add_dependencies(install-runtimes install-runtimes-${name})
-        add_dependencies(install-runtimes-stripped install-runtimes-${name}-stripped)
-        if(LLVM_INCLUDE_TESTS)
-          add_dependencies(check-runtimes check-runtimes-${name})
-          add_dependencies(runtimes-test-depends runtimes-test-depends-${name})
-        endif()
-        foreach(runtime_name ${runtime_names})
-          add_dependencies(${runtime_name} ${runtime_name}-${name})
-          add_dependencies(install-${runtime_name} install-${runtime_name}-${name})
-          add_dependencies(install-${runtime_name}-stripped install-${runtime_name}-${name}-stripped)
-        endforeach()
-      endforeach()
 
-      foreach(multilib ${LLVM_RUNTIME_MULTILIBS})
-        foreach(name ${LLVM_RUNTIME_MULTILIB_${multilib}_TARGETS})
-          runtime_register_target(${name}+${multilib} ${name}
-            DEPENDS runtimes-${name}
-            CMAKE_ARGS -DLLVM_RUNTIMES_PREFIX=${name}/
-                       -DLLVM_RUNTIMES_LIBDIR_SUBDIR=${multilib})
-          add_dependencies(runtimes runtimes-${name}+${multilib})
-          add_dependencies(runtimes-configure runtimes-${name}+${multilib}-configure)
-          add_dependencies(install-runtimes install-runtimes-${name}+${multilib})
-          add_dependencies(install-runtimes-stripped install-runtimes-${name}+${multilib}-stripped)
-          foreach(runtime_name ${runtime_names})
-            add_dependencies(${runtime_name} ${runtime_name}-${name}+${multilib})
-            add_dependencies(install-${runtime_name} install-${runtime_name}-${name}+${multilib})
-            add_dependencies(install-${runtime_name}-stripped install-${runtime_name}-${name}+${multilib}-stripped)
-          endforeach()
-        endforeach()
-      endforeach()
-    endif()
 
-    if(NOT LLVM_BUILD_INSTRUMENTED AND CLANG_ENABLE_BOOTSTRAP)
-      # TODO: This is a hack needed because the libcxx headers are copied into the
-      # build directory during configuration. Without that step the clang in the
-      # build directory cannot find the C++ headers in certain configurations.
-      # I need to build a mechanism for runtime projects to provide CMake code
-      # that executes at LLVM configuration time to handle this case.
-      add_dependencies(clang-bootstrap-deps runtimes-configure)
-      # We need to add the runtimes as a dependency because compiler-rt can be
-      # built as part of runtimes and we need the profile runtime for PGO
-      add_dependencies(clang-bootstrap-deps runtimes)
-    endif()
 
-    if(LLVM_INCLUDE_TESTS)
-      set_property(GLOBAL APPEND PROPERTY LLVM_ADDITIONAL_TEST_DEPENDS runtimes-test-depends)
-      set_property(GLOBAL APPEND PROPERTY LLVM_ADDITIONAL_TEST_TARGETS check-runtimes)
 
-      set(RUNTIMES_TEST_DEPENDS
-          FileCheck
-          count
-          llvm-nm
-          llvm-objdump
-          llvm-xray
-          not
-          obj2yaml
-          sancov
-          sanstats
-          gtest_main
-          gtest
-        )
-      foreach(target ${test_targets} ${SUB_CHECK_TARGETS})
-        add_dependencies(${target} ${RUNTIMES_TEST_DEPENDS})
-      endforeach()
-    endif()
-  endif()
-endif()

runtimes/CMakeLists.txt

+# This file handles building LLVM runtime sub-projects.
+cmake_minimum_required(VERSION 3.13.4)
+
+if(POLICY CMP0068)
+  cmake_policy(SET CMP0068 NEW)
+  set(CMAKE_BUILD_WITH_INSTALL_NAME_DIR ON)
+endif()
+
+if(POLICY CMP0075)
+  cmake_policy(SET CMP0075 NEW)
+endif()
+
+if(POLICY CMP0077)
+  cmake_policy(SET CMP0077 NEW)
+endif()
+
+project(Runtimes C CXX ASM)
+
+set(LLVM_ALL_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind;openmp")
+set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
+  "Semicolon-separated list of runtimes to build (${LLVM_ALL_RUNTIMES}), or \"all\".")
+if(LLVM_ENABLE_RUNTIMES STREQUAL "all" )
+  set(LLVM_ENABLE_RUNTIMES ${LLVM_ALL_RUNTIMES})
+endif()
+
+foreach(proj ${LLVM_ENABLE_RUNTIMES})
+  set(proj_dir "${CMAKE_CURRENT_SOURCE_DIR}/../${proj}")
+  if(IS_DIRECTORY ${proj_dir} AND EXISTS ${proj_dir}/CMakeLists.txt)
+    list(APPEND runtimes ${proj_dir})
+  else()
+    message(FATAL_ERROR "LLVM_ENABLE_RUNTIMES requests ${proj} but directory not found: ${proj_dir}")
+  endif()
+  string(TOUPPER "${proj}" canon_name)
+  STRING(REGEX REPLACE "-" "_" canon_name ${canon_name})
+  set(LLVM_EXTERNAL_${canon_name}_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../${proj}")
+endforeach()
+
+function(runtime_register_component name)
+  set_property(GLOBAL APPEND PROPERTY SUB_COMPONENTS ${name})
+endfunction()
+
+find_package(LLVM PATHS "${LLVM_BINARY_DIR}" NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
+find_package(Clang PATHS "${LLVM_BINARY_DIR}" NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
+
+# Add path for custom and the LLVM build's modules to the CMake module path.
+list(INSERT CMAKE_MODULE_PATH 0
+  "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
+  "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules"
+  "${CMAKE_CURRENT_SOURCE_DIR}/../llvm/cmake"
+  "${CMAKE_CURRENT_SOURCE_DIR}/../llvm/cmake/modules"
+)
+
+function(get_compiler_rt_path path)
+  foreach(entry ${runtimes})
+    get_filename_component(projName ${entry} NAME)
+    if("${projName}" MATCHES "compiler-rt")
+      set(${path} ${entry} PARENT_SCOPE)
+      return()
+    endif()
+  endforeach()
+endfunction()
+
+# Some of the runtimes will conditionally use the compiler-rt sanitizers
+# to make this work smoothly we ensure that compiler-rt is added first in
+# the list of sub-projects. This allows other sub-projects to have checks
+# like `if(TARGET asan)` to enable building with asan.
+get_compiler_rt_path(compiler_rt_path)
+if(compiler_rt_path)
+  list(REMOVE_ITEM runtimes ${compiler_rt_path})
+  if(NOT DEFINED LLVM_BUILD_COMPILER_RT OR LLVM_BUILD_COMPILER_RT)
+    list(INSERT runtimes 0 ${compiler_rt_path})
+  endif()
+endif()
+
+# Setting these variables will allow the sub-build to put their outputs into
+# the library and bin directories of the top-level build.
+set(LLVM_LIBRARY_OUTPUT_INTDIR ${LLVM_LIBRARY_DIR})
+set(LLVM_RUNTIME_OUTPUT_INTDIR ${LLVM_TOOLS_BINARY_DIR})
+
+# This variable makes sure that e.g. llvm-lit is found.
+set(LLVM_MAIN_SRC_DIR ${LLVM_BUILD_MAIN_SRC_DIR})
+set(LLVM_CMAKE_PATH ${LLVM_MAIN_SRC_DIR}/cmake/modules)
+
+# This variable is used by individual runtimes to locate LLVM files.
+set(LLVM_PATH ${LLVM_BUILD_MAIN_SRC_DIR})
+
+if(APPLE)
+  set(LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
+endif()
+
+include(CheckLibraryExists)
+include(CheckCCompilerFlag)
+
+# We don't have libc++ (yet)...
+set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -nostdinc++ -nostdlib++")
+
+# ...but we need access to libc++ headers for CMake checks to succeed.
+if (LLVM_EXTERNAL_LIBCXX_SOURCE_DIR AND "libcxx" IN_LIST LLVM_ENABLE_RUNTIMES)
+  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -isystem ${LLVM_EXTERNAL_LIBCXX_SOURCE_DIR}/include")
+endif()
+
+# Avoid checking whether the compiler is working.
+set(LLVM_COMPILER_CHECKED ON)
+
+# Handle common options used by all runtimes.
+include(AddLLVM)
+include(HandleLLVMOptions)
+include(FindPythonInterp)
+
+# Remove the -nostdlib++ option we've added earlier.
+string(REPLACE "-nostdlib++" "" CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
+
+# Use libtool instead of ar if you are both on an Apple host, and targeting Apple.
+if(CMAKE_HOST_APPLE AND APPLE)
+  include(UseLibtool)
+endif()
+
+# This can be used to detect whether we're in the runtimes build.
+set(RUNTIMES_BUILD ON)
+
+foreach(entry ${runtimes})
+  get_filename_component(projName ${entry} NAME)
+
+  # TODO: Clean this up as part of an interface standardization
+  string(REPLACE "-" "_" canon_name ${projName})
+  string(TOUPPER ${canon_name} canon_name)
+
+  # The subdirectories need to treat this as standalone builds. D57992 tried
+  # to get rid of this, but the runtimes treat *_STANDALONE_BUILD=OFF as if
+  # llvm & clang are configured in the same CMake, and setup dependencies
+  # against their targets. OpenMP has fixed the issue so we don't set the
+  # variable.
+  if (NOT ${canon_name} STREQUAL "OPENMP")
+    set(${canon_name}_STANDALONE_BUILD ON)
+  endif()
+
+  if(LLVM_RUNTIMES_LIBDIR_SUBDIR)
+    set(${canon_name}_LIBDIR_SUBDIR "${LLVM_RUNTIMES_LIBDIR_SUBDIR}" CACHE STRING "" FORCE)
+  endif()
+
+  # Setting a variable to let sub-projects detect which other projects
+  # will be included under here.
+  set(HAVE_${canon_name} ON)
+endforeach()
+
+# We do this in two loops so that HAVE_* is set for each runtime before the
+# other runtimes are added.
+foreach(entry ${runtimes})
+  get_filename_component(projName ${entry} NAME)
+
+  # Between each sub-project we want to cache and clear the LIT properties
+  set_property(GLOBAL PROPERTY LLVM_LIT_TESTSUITES)
+  set_property(GLOBAL PROPERTY LLVM_LIT_PARAMS)
+  set_property(GLOBAL PROPERTY LLVM_LIT_DEPENDS)
+  set_property(GLOBAL PROPERTY LLVM_LIT_EXTRA_ARGS)
+
+  add_subdirectory(${entry} ${projName})
+
+  get_property(LLVM_LIT_TESTSUITES GLOBAL PROPERTY LLVM_LIT_TESTSUITES)
+  get_property(LLVM_LIT_PARAMS GLOBAL PROPERTY LLVM_LIT_PARAMS)
+  get_property(LLVM_LIT_DEPENDS GLOBAL PROPERTY LLVM_LIT_DEPENDS)
+  get_property(LLVM_LIT_EXTRA_ARGS GLOBAL PROPERTY LLVM_LIT_EXTRA_ARGS)
+
+  list(APPEND RUNTIMES_LIT_TESTSUITES ${LLVM_LIT_TESTSUITES})
+  list(APPEND RUNTIMES_LIT_PARAMS ${LLVM_LIT_PARAMS})
+  list(APPEND RUNTIMES_LIT_DEPENDS ${LLVM_LIT_DEPENDS})
+  list(APPEND RUNTIMES_LIT_EXTRA_ARGS ${LLVM_LIT_EXTRA_ARGS})
+endforeach()
+
+if(LLVM_INCLUDE_TESTS)
+  # Add a global check rule now that all subdirectories have been traversed
+  # and we know the total set of lit testsuites.
+
+  add_lit_target(check-runtimes
+    "Running all regression tests"
+    ${RUNTIMES_LIT_TESTSUITES}
+    PARAMS ${RUNTIMES_LIT_PARAMS}
+    DEPENDS ${RUNTIMES_LIT_DEPENDS}
+    ARGS ${RUNTIMES_LIT_EXTRA_ARGS}
+    )
+  add_custom_target(runtimes-test-depends DEPENDS ${RUNTIMES_LIT_DEPENDS})
+endif()
+
+get_property(SUB_COMPONENTS GLOBAL PROPERTY SUB_COMPONENTS)
+if(SUB_COMPONENTS)
+  list(REMOVE_DUPLICATES SUB_COMPONENTS)
+  foreach(component ${SUB_COMPONENTS})
+    if(NOT TARGET ${component})
+      message(SEND_ERROR "Missing target for runtime component ${component}!")
+      continue()
+    endif()
+
+    if(TARGET check-${component})
+      list(APPEND SUB_CHECK_TARGETS check-${component})
+    endif()
+
+    if(TARGET install-${component})
+      list(APPEND SUB_INSTALL_TARGETS install-${component})
+    endif()
+    if(TARGET install-${component}-stripped)
+      list(APPEND SUB_INSTALL_TARGETS install-${component}-stripped)
+    endif()
+  endforeach()
+
+  if(LLVM_RUNTIMES_TARGET)
+    configure_file(
+      ${CMAKE_CURRENT_SOURCE_DIR}/Components.cmake.in
+      ${LLVM_BINARY_DIR}/runtimes/${LLVM_RUNTIMES_TARGET}/Components.cmake)
+  else()
+    configure_file(
+      ${CMAKE_CURRENT_SOURCE_DIR}/Components.cmake.in
+      ${LLVM_BINARY_DIR}/runtimes/Components.cmake)
+  endif()
+endif()