Remain silent if reconfiguration has no effect

cmake/Modules/FindComputeCpp.cmake

@@ -154,11 +154,14 @@ else()
   if(NOT ComputeCpp_INFO_EXECUTABLE_RESULT EQUAL "0")
     message(WARNING "platform - Error checking platform support!")
   else()
-    mark_as_advanced(COMPUTECPP_PLATFORM_IS_SUPPORTED)
-    if (COMPUTECPP_PLATFORM_IS_SUPPORTED)
-      message(STATUS "platform - your system can support ComputeCpp")
-    else()
-      message(STATUS "platform - your system is not officially supported")
+    if(NOT PREVIOUS_COMPUTECPP_PLATFORM_IS_SUPPORTED STREQUAL COMPUTECPP_PLATFORM_IS_SUPPORTED)
+      mark_as_advanced(COMPUTECPP_PLATFORM_IS_SUPPORTED)
+      if (COMPUTECPP_PLATFORM_IS_SUPPORTED)
+        message(STATUS "platform - your system can support ComputeCpp")
+      else()
+        message(STATUS "platform - your system is not officially supported")
+      endif()
+      set(PREVIOUS_COMPUTECPP_PLATFORM_IS_SUPPORTED "${COMPUTECPP_PLATFORM_IS_SUPPORTED}" CACHE INTERNAL "Remember not to re-print when there's no change")
     endif()
   endif()
 endif()
@@ -202,7 +205,11 @@ foreach (bitcode IN ITEMS ${COMPUTECPP_BITCODE})
   endif()
 endforeach()
 
-message(STATUS "compute++ flags - ${COMPUTECPP_DEVICE_COMPILER_FLAGS}")
+if(NOT PREVIOUS_COMPUTECPP_DEVICE_COMPILER_FLAGS STREQUAL COMPUTECPP_DEVICE_COMPILER_FLAGS)
+  message(STATUS "compute++ flags - ${COMPUTECPP_DEVICE_COMPILER_FLAGS}")
+  set(PREVIOUS_COMPUTECPP_DEVICE_COMPILER_FLAGS "${COMPUTECPP_DEVICE_COMPILER_FLAGS}" CACHE INTERNAL "Remember not to re-print when there's no change")
+endif()
+
 
 if(CMAKE_COMPILER_IS_GNUCXX)
   if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.8)