[llvm] r360196 - [CMake] Detecting python modules should be cached

[Chris Bieneman via llvm-commits]

Author: cbieneman
Date: Tue May  7 14:46:55 2019
New Revision: 360196

URL: http://llvm.org/viewvc/llvm-project?rev=360196&view=rev
Log:
[CMake] Detecting python modules should be cached

Summary: This requres exec-ing python, which in a trace I ran of the CMake re-configure time took ~2% of the reconfigure time.

Reviewers: phosek, smeenai, compnerd

Subscribers: mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61402

Modified:
    llvm/trunk/cmake/config-ix.cmake

Modified: llvm/trunk/cmake/config-ix.cmake
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/cmake/config-ix.cmake?rev=360196&r1=360195&r2=360196&view=diff
==============================================================================
--- llvm/trunk/cmake/config-ix.cmake (original)
+++ llvm/trunk/cmake/config-ix.cmake Tue May  7 14:46:55 2019
@@ -606,16 +606,19 @@ function(find_python_module module)
   string(REPLACE "." "_" module_name ${module})
   string(TOUPPER ${module_name} module_upper)
   set(FOUND_VAR PY_${module_upper}_FOUND)
+  if (DEFINED ${FOUND_VAR})
+    return()
+  endif()
 
   execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c" "import ${module}"
     RESULT_VARIABLE status
     ERROR_QUIET)
 
   if(status)
-    set(${FOUND_VAR} 0 PARENT_SCOPE)
+    set(${FOUND_VAR} OFF CACHE BOOL "Failed to find python module '${module}'")
     message(STATUS "Could NOT find Python module ${module}")
   else()
-    set(${FOUND_VAR} 1 PARENT_SCOPE)
+  set(${FOUND_VAR} ON CACHE BOOL "Found python module '${module}'")
     message(STATUS "Found Python module ${module}")
   endif()
 endfunction()