[CMake] Support single target builtins build on Darwin

[phosek]

Summary

This change allows cross-compiling compiler-rt builtins for multiple targets as part of runtimes on Darwin. This functionality is already supported on other platforms.

[beanz]

cmake/modules/LLVMExternalProjectUtils.cmake

47

This part of the change can't be done without causing problems on Darwin. llvm-ar and llvm-ranlib don't correctly handle fat archives on Darwin, so if you have a Darwin target we really don't want this to be the case. That's why this isn't defaulted.

You really need to just override the TOOLCHAIN_TOOLS option at the call site. We also probably shouldn't have lld in the list, but it doesn't have any adverse side effects because we don't force its use.

runtimes/CMakeLists.txt

156

I believe this patch will misbehave if LLVM_BUILTIN_TARGETS is a Darwin target, so we probably need to put some sort of protection in to catch that.

[beanz]

One minor style comment, otherwise looks good to me.

runtimes/CMakeLists.txt

185

This shouldn't need to be semi-colon separated. Space separated should work because TOOLCHAIN_TOOLS is a list parameter.

[beanz]

LGTM!

[phosek]

Thanks, could you also please take at D30958?

cmake/modules/LLVMExternalProjectUtils.cmake

 #     Exclude this project from the all target
 #   NO_INSTALL
 #     Don't generate install targets for this project
 #   ALWAYS_CLEAN
 #     Always clean the sub-project before building
 #   CMAKE_ARGS arguments...
 #     Optional cmake arguments to pass when configuring the project
 #   TOOLCHAIN_TOOLS targets...
-#     Targets for toolchain tools (defaults to clang;lld)
+#     Targets for toolchain tools (defaults to clang;lld;llvm-ar;llvm-ranlib)
 #   DEPENDS targets...
 #     Targets that this project depends on
 #   EXTRA_TARGETS targets...
 #     Extra targets in the subproject to generate targets for
 #   PASSTHROUGH_PREFIXES prefix...
 #     Extra variable prefixes (name is always included) to pass down
 #   )
 function(llvm_ExternalProject_Add name source_dir)
   cmake_parse_arguments(ARG
     "USE_TOOLCHAIN;EXCLUDE_FROM_ALL;NO_INSTALL;ALWAYS_CLEAN"
     "SOURCE_DIR"
     "CMAKE_ARGS;TOOLCHAIN_TOOLS;RUNTIME_LIBRARIES;DEPENDS;EXTRA_TARGETS;PASSTHROUGH_PREFIXES"
     ${ARGN})
   canonicalize_tool_name(${name} nameCanon)
   if(NOT ARG_TOOLCHAIN_TOOLS)
-    set(ARG_TOOLCHAIN_TOOLS clang lld)
-    if(NOT APPLE AND NOT WIN32)
-      list(APPEND ARG_TOOLCHAIN_TOOLS llvm-ar llvm-ranlib)
-    endif()
+    set(ARG_TOOLCHAIN_TOOLS clang lld llvm-ar llvm-ranlib)
   endif()
   foreach(tool ${ARG_TOOLCHAIN_TOOLS})
     if(TARGET ${tool})
       list(APPEND TOOLCHAIN_TOOLS ${tool})
       list(APPEND TOOLCHAIN_BINS $<TARGET_FILE:${tool}>)
     endif()
   endforeach()
 

runtimes/CMakeLists.txt

if(${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
   # 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})
 
+  if(APPLE)
+   set(LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
+  endif()
+
   # Handle common options used by all runtimes.
   include(AddLLVM)
   include(HandleLLVMOptions)
 
   foreach(entry ${runtimes})
     get_filename_component(projName ${entry} NAME)
 
     # TODO: Clean this up as part of an interface standardization
else() # if this is included from LLVM's CMake
   include(${LLVM_BINARY_DIR}/runtimes/Components.cmake OPTIONAL)
   set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${LLVM_BINARY_DIR}/runtimes/Components.cmake)
   include(LLVMExternalProjectUtils)
 
   # 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.
   if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/compiler-rt)
-    if(APPLE OR NOT LLVM_BUILTIN_TARGETS)
+    if(NOT LLVM_BUILTIN_TARGETS)
       llvm_ExternalProject_Add(builtins
                                ${CMAKE_CURRENT_SOURCE_DIR}/compiler-rt/lib/builtins
                                CMAKE_ARGS -DLLVM_LIBRARY_OUTPUT_INTDIR=${LLVM_LIBRARY_DIR}
                                           -DLLVM_RUNTIME_OUTPUT_INTDIR=${LLVM_TOOLS_BINARY_DIR}
                                           -DCMAKE_C_COMPILER_TARGET=${TARGET_TRIPLE}
                                           -DCMAKE_ASM_COMPILER_TARGET=${TARGET_TRIPLE}
                                PASSTHROUGH_PREFIXES COMPILER_RT
                                USE_TOOLCHAIN)
else()
                                CMAKE_ARGS -DLLVM_LIBRARY_OUTPUT_INTDIR=${LLVM_LIBRARY_DIR}
                                           -DLLVM_RUNTIME_OUTPUT_INTDIR=${LLVM_TOOLS_BINARY_DIR}
                                           -DCMAKE_C_COMPILER_TARGET=${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}
                                PASSTHROUGH_PREFIXES COMPILER_RT
                                USE_TOOLCHAIN)
         add_dependencies(builtins builtins-${target})
       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)