[CMake][runtimes] Use cmake_parse_arguments in runtimes functions

[phosek]

Summary

This improves the handling of list arguments.

[beanz]

LGTM.

Generally we frown on commit messages as concise as your description here. Might be worth a quick sentence or two explaining why cmake_parse_aguments is better as a breadcrumb for anyone who comes along in the future.

llvm/trunk/runtimes/CMakeLists.txt

foreach(entry ${runtimes})
 
     string(FIND ${projName} "lib" LIB_IDX)
     if(LIB_IDX EQUAL 0)
       string(SUBSTRING ${projName} 3 -1 projName)
     endif()
     list(APPEND runtime_names ${projName})
   endforeach()
 
-  function(runtime_default_target deps prefixes)
+  function(runtime_default_target)
+    cmake_parse_arguments(ARG "" "" "DEPS;PREFIXES" ${ARGN})
+
     include(${LLVM_BINARY_DIR}/runtimes/Components.cmake OPTIONAL)
     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})
       if(LLVM_INCLUDE_TESTS)
         list(APPEND test_targets check-${runtime_name})
       endif()
     endforeach()
 
     if(LLVM_INCLUDE_TESTS)
       list(APPEND test_targets runtimes-test-depends check-runtimes)
     endif()
 
     llvm_ExternalProject_Add(runtimes
                              ${CMAKE_CURRENT_SOURCE_DIR}
-                             DEPENDS ${deps}
+                             DEPENDS ${ARG_DEPS}
                              # Builtins were built separately above
                              CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=Off
                                         -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
                                         -DLLVM_LIBRARY_DIR=${LLVM_LIBRARY_DIR}
                                         -DCMAKE_C_COMPILER_WORKS=ON
                                         -DCMAKE_CXX_COMPILER_WORKS=ON
                                         -DCMAKE_ASM_COMPILER_WORKS=ON
-                             PASSTHROUGH_PREFIXES ${prefixes}
+                             PASSTHROUGH_PREFIXES ${ARG_PREFIXES}
                              EXTRA_TARGETS ${extra_targets}
                                            ${test_targets}
                                            ${SUB_COMPONENTS}
                                            ${SUB_CHECK_TARGETS}
                                            ${SUB_INSTALL_TARGETS}
                              USE_TOOLCHAIN
                              ${EXTRA_ARGS})
   endfunction()
 
   # runtime_register_target(target)
   #   Utility function to register external runtime target.
-  function(runtime_register_target name target deps prefixes)
+  function(runtime_register_target name target)
+    cmake_parse_arguments(ARG "" "" "DEPS" ${ARGN})
     include(${LLVM_BINARY_DIR}/runtimes/${name}/Components.cmake OPTIONAL)
     set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${LLVM_BINARY_DIR}/runtimes/${name}/Components.cmake)
 
-    set(${name}_deps ${deps})
+    set(${name}_deps ${ARG_DEPS})
     if(NOT name STREQUAL target)
       list(APPEND ${name}_deps runtimes-${target})
     endif()
 
     foreach(runtime_name ${runtime_names})
       list(APPEND ${name}_extra_targets
         "${runtime_name}:${runtime_name}-${name}"
         "install-${runtime_name}:install-${runtime_name}-${name}")
llvm_ExternalProject_Add(runtimes-${name}
                                         -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}
                              TOOLCHAIN_TOOLS clang lld llvm-ar llvm-ranlib
-                             PASSTHROUGH_PREFIXES ${prefixes}
                              EXTRA_TARGETS ${${name}_extra_targets}
                                            ${${name}_test_targets}
                              USE_TOOLCHAIN
                              ${EXTRA_ARGS})
   endfunction()
 
   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(${deps} ${prefixes})
+      runtime_default_target(
+        DEPS ${deps}
+        PREFIXES ${prefixes}
+        )
     else()
       if("default" IN_LIST LLVM_RUNTIME_TARGETS)
-        runtime_default_target(${deps} ${prefixes})
+        runtime_default_target(
+          DEPS ${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)
         if(LLVM_INCLUDE_TESTS)
           add_custom_target(check-runtimes)
           add_custom_target(runtimes-test-depends)
           set(test_targets "")
         endif()
       endif()
 
       foreach(name ${LLVM_RUNTIME_TARGETS})
         set(target ${name})
         string(REPLACE ":" ";" target_list ${target})
         list(GET target_list 0 name)
         list(LENGTH target_list target_list_len)
         if(${target_list_len} GREATER 1)
           list(GET target_list 1 target)
         endif()
 
-        runtime_register_target(${name} ${target} ${deps} ${prefixes})
+        runtime_register_target(${name} ${target}
+          DEPS ${deps}
+          )
 
         add_dependencies(runtimes runtimes-${name})
         add_dependencies(runtimes-configure runtimes-${name}-configure)
         add_dependencies(install-runtimes install-runtimes-${name})
         if(LLVM_INCLUDE_TESTS)
           add_dependencies(check-runtimes check-runtimes-${name})
           add_dependencies(runtimes-test-depends runtimes-test-depends-${name})
         endif()