--- old/src/hotspot/share/c1/c1_ValueStack.hpp	2018-12-03 15:48:57.244420154 -0800
+++ new/src/hotspot/share/c1/c1_ValueStack.hpp	2018-12-03 15:48:57.092414348 -0800
@@ -204,8 +204,10 @@
   Value lock_at(int i) const                     { return _locks.at(i); }
 
   // SSA form IR support
-  void setup_phi_for_stack(BlockBegin* b, int index);
-  void setup_phi_for_local(BlockBegin* b, int index);
+  void setup_phi_for_stack(BlockBegin* b, int index, Value existing_value, Value new_value);
+  void setup_phi_for_local(BlockBegin* b, int index, Value existing_value, Value new_value);
+
+  ciType* merge_if_flattened_array_types(Value existing_value, Value new_value);
 
   // debugging
   void print()  PRODUCT_RETURN;