--- old/src/hotspot/share/runtime/thread.cpp	2018-09-14 13:58:52.557592016 -0400
+++ new/src/hotspot/share/runtime/thread.cpp	2018-09-14 13:58:52.297592026 -0400
@@ -1599,6 +1599,11 @@
     SafepointMechanism::initialize_header(this);
   }
 
+#ifdef _WIN64
+  _windows_saved_rsi = NULL;
+  _windows_saved_rdi = NULL;
+#endif // _WIN64
+
   pd_initialize();
 }