[cmake] Fix get_llvm_lit_path() to respect LLVM_EXTERNAL_LIT always

Refactor the get_llvm_lit_path() logic to respect LLVM_EXTERNAL_LIT,
and require the fallback to be defined explicitly
as LLVM_DEFAULT_EXTERNAL_LIT. This fixes building libcxx standalone
after r346888.

The old logic was using LLVM_EXTERNAL_LIT both as user-defined cache
variable and an optional pre-definition of default value from caller
(e.g. libcxx). It included a hack to make this work by assigning
the value back and forth but it was fragile and stopped working
in libcxx.

The new logic is simpler and more transparent. Default value is
provided in a separate variable, and used only when user-specified
variable is empty (i.e. not overriden).

Differential Revision: https://reviews.llvm.org/D57282

llvm-svn: 352374

4 files changed, 3 insertions, 4 deletions

diff --git a/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake b/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
index 70eed1d70ba..11c13315585 100644
--- a/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
+++ b/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
@@ -116,7 +116,7 @@ macro(configure_out_of_tree_llvm)
     # Required LIT Configuration ------------------------------------------------
     # Define the default arguments to use with 'lit', and an option for the user
     # to override.
-    set(LLVM_EXTERNAL_LIT "${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py")
+    set(LLVM_DEFAULT_EXTERNAL_LIT "${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py")
     set(LIT_ARGS_DEFAULT "-sv --show-xfail --show-unsupported")
     if (MSVC OR XCODE)
       set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
diff --git a/libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake b/libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake
index 3b19c5c15cd..3296c0c8088 100644
--- a/libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake
+++ b/libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake
@@ -119,7 +119,7 @@ macro(configure_out_of_tree_llvm)
     # Required LIT Configuration ------------------------------------------------
     # Define the default arguments to use with 'lit', and an option for the user
     # to override.
-    set(LLVM_EXTERNAL_LIT "${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py")
+    set(LLVM_DEFAULT_EXTERNAL_LIT "${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py")
     set(LIT_ARGS_DEFAULT "-sv --show-xfail --show-unsupported")
     if (MSVC OR XCODE)
       set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
diff --git a/lldb/cmake/modules/LLDBStandalone.cmake b/lldb/cmake/modules/LLDBStandalone.cmake
index 25da1b81015..8101637095f 100644
--- a/lldb/cmake/modules/LLDBStandalone.cmake
+++ b/lldb/cmake/modules/LLDBStandalone.cmake
@@ -23,7 +23,7 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   set(LLVM_MAIN_INCLUDE_DIR ${LLVM_BUILD_MAIN_INCLUDE_DIR} CACHE PATH "Path to llvm/include")
   set(LLVM_LIBRARY_DIR ${LLVM_BUILD_LIBRARY_DIR} CACHE PATH "Path to llvm/lib")
   set(LLVM_BINARY_DIR ${LLVM_BUILD_BINARY_DIR} CACHE PATH "Path to LLVM build tree")
-  set(LLVM_EXTERNAL_LIT ${LLVM_TOOLS_BINARY_DIR}/llvm-lit CACHE PATH "Path to llvm-lit")
+  set(LLVM_DEFAULT_EXTERNAL_LIT ${LLVM_TOOLS_BINARY_DIR}/llvm-lit CACHE PATH "Path to llvm-lit")
 
   if(CMAKE_CROSSCOMPILING)
     set(LLVM_NATIVE_BUILD "${LLDB_PATH_TO_LLVM_BUILD}/NATIVE")
diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index 4dbc0ddaf4f..0df6845aaa7 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -1280,7 +1280,6 @@ function(get_llvm_lit_path base_dir file_name)
   cmake_parse_arguments(ARG "ALLOW_EXTERNAL" "" "" ${ARGN})
 
   if (ARG_ALLOW_EXTERNAL)
-    set(LLVM_DEFAULT_EXTERNAL_LIT "${LLVM_EXTERNAL_LIT}")
     set (LLVM_EXTERNAL_LIT "" CACHE STRING "Command used to spawn lit")
     if ("${LLVM_EXTERNAL_LIT}" STREQUAL "")
       set(LLVM_EXTERNAL_LIT "${LLVM_DEFAULT_EXTERNAL_LIT}")