[cmake] Use LLVMConfig.cmake instead of llvm-config to set some variables.

Previously in order to support cross-compiling, we were setting these variables
in build-script. Now that we are using LLVMConfig.cmake, passing in these values
are no longer necessary. As an added benefit, Swift when not cross compiling,
does not need to set these variables anyways.

rdar://26154980

Author: gottesmm

cmake/modules/SwiftSharedCMakeConfig.cmake

@@ -117,10 +117,6 @@ macro(swift_common_standalone_build_config product is_cross_compiling)
   if(${is_cross_compiling})
     # Can't run llvm-config from the cross-compiled LLVM.
     set(LLVM_TOOLS_BINARY_DIR "" CACHE PATH "Path to llvm/bin")
-    set(LLVM_LIBRARY_DIR "" CACHE PATH "Path to llvm/lib")
-    set(LLVM_MAIN_INCLUDE_DIR "" CACHE PATH "Path to llvm/include")
-    set(LLVM_BINARY_DIR "" CACHE PATH "Path to LLVM build tree")
-    set(LLVM_MAIN_SRC_DIR "" CACHE PATH "Path to LLVM source tree")
   else()
     # Rely on llvm-config.
     _swift_llvm_config_info(
@@ -138,10 +134,6 @@ macro(swift_common_standalone_build_config product is_cross_compiling)
     mark_as_advanced(LLVM_ENABLE_ASSERTIONS)
 
     set(LLVM_TOOLS_BINARY_DIR "${llvm_config_tools_binary_dir}" CACHE PATH "Path to llvm/bin")
-    set(LLVM_LIBRARY_DIR "${llvm_config_library_dir}" CACHE PATH "Path to llvm/lib")
-    set(LLVM_MAIN_INCLUDE_DIR "${llvm_config_include_dir}" CACHE PATH "Path to llvm/include")
-    set(LLVM_BINARY_DIR "${llvm_config_obj_root}" CACHE PATH "Path to LLVM build tree")
-    set(LLVM_MAIN_SRC_DIR "${llvm_config_src_dir}" CACHE PATH "Path to LLVM source tree")
 
     set(${product}_NATIVE_LLVM_TOOLS_PATH "${LLVM_TOOLS_BINARY_DIR}")
     set(${product}_NATIVE_CLANG_TOOLS_PATH "${LLVM_TOOLS_BINARY_DIR}")
@@ -175,6 +167,11 @@ macro(swift_common_standalone_build_config product is_cross_compiling)
   set(LLVM_TOOLS_BINARY_DIR "${LLVM_TOOLS_BINARY_DIR_saved}")
   set(LLVM_ENABLE_ASSERTIONS "${LLVM_ENABLE_ASSERTIONS_saved}")
 
+  precondition_translate_flag(LLVM_BUILD_LIBRARY_DIR LLVM_LIBRARY_DIR)
+  precondition_translate_flag(LLVM_BUILD_MAIN_INCLUDE_DIR LLVM_MAIN_INCLUDE_DIR)
+  precondition_translate_flag(LLVM_BUILD_BINARY_DIR LLVM_BINARY_DIR)
+  precondition_translate_flag(LLVM_BUILD_MAIN_SRC_DIR LLVM_MAIN_SRC_DIR)
+
   # Clang
   set(${product}_PATH_TO_CLANG_SOURCE "${PATH_TO_LLVM_SOURCE}/tools/clang"
       CACHE PATH "Path to Clang source code.")

utils/build-script-impl

@@ -1836,10 +1836,6 @@ for host in "${ALL_HOSTS[@]}"; do
                     cmake_options=(
                         "${cmake_options[@]}"
                         -DLLVM_TOOLS_BINARY_DIR:PATH=$(build_directory ${host} llvm)/bin
-                        -DLLVM_LIBRARY_DIR:PATH=$(build_directory ${host} llvm)/lib
-                        -DLLVM_MAIN_INCLUDE_DIR:PATH=$(build_directory ${host} llvm)/include
-                        -DLLVM_BINARY_DIR:PATH=$(build_directory ${host} llvm)
-                        -DLLVM_MAIN_SRC_DIR:PATH="${LLVM_SOURCE_DIR}"
                     )
                 else
                     build_perf_testsuite_this_time=$(true_false "$(not ${SKIP_BUILD_BENCHMARKS})")
@@ -1862,10 +1858,6 @@ for host in "${ALL_HOSTS[@]}"; do
                     cmake_options=(
                         "${cmake_options[@]}"
                         -DLLVM_TOOLS_BINARY_DIR:PATH=/tmp/dummy
-                        -DLLVM_LIBRARY_DIR:PATH="${build_dir}"
-                        -DLLVM_MAIN_INCLUDE_DIR:PATH=/tmp/dummy
-                        -DLLVM_BINARY_DIR:PATH=$(build_directory ${host} llvm)
-                        -DLLVM_MAIN_SRC_DIR:PATH="${LLVM_SOURCE_DIR}"
                     )
                 fi