--- old/src/cpu/x86/vm/templateInterpreter_x86_64.cpp	2011-10-19 08:37:06.151187267 -0700
+++ new/src/cpu/x86/vm/templateInterpreter_x86_64.cpp	2011-10-19 08:37:05.877607564 -0700
@@ -1622,6 +1622,12 @@
     // sender_sp is fp+16 XXX
     intptr_t* locals = interpreter_frame->sender_sp() + max_locals - 1;
 
+#ifdef ASSERT
+    if (caller->is_interpreted_frame()) {
+      assert(locals < caller->fp() + frame::interpreter_frame_initial_sp_offset, "bad placement");
+    }
+#endif
+
     interpreter_frame->interpreter_frame_set_locals(locals);
     BasicObjectLock* montop = interpreter_frame->interpreter_frame_monitor_begin();
     BasicObjectLock* monbot = montop - moncount;