src/share/vm/opto/matcher.hpp

*** 82,91 ****
--- 82,92 ----
    Node_List &_proj_list;        // For Machine nodes killing many values
  
    Node_Array _shared_nodes;
  
    debug_only(Node_Array _old2new_map;)   // Map roots of ideal-trees to machine-roots
+   debug_only(Node_Array _new2old_map;)   // Maps machine nodes back to ideal
  
    // Accessors for the inherited field PhaseTransform::_nodes:
    void   grow_new_node_array(uint idx_limit) {
      _nodes.map(idx_limit-1, NULL);
    }
*** 386,392 ****
--- 387,397 ----
    static bool post_store_load_barrier(const Node* mb);
  
  
  #ifdef ASSERT
    void dump_old2new_map();      // machine-independent to machine-dependent
+ 
+   Node* find_old_node(Node* new_node) {
+     return _new2old_map[new_node->_idx];
+   }
  #endif
  };