*** old/src/share/vm/opto/node.hpp	Wed Nov 25 15:47:03 2015
--- new/src/share/vm/opto/node.hpp	Wed Nov 25 15:47:03 2015

*** 290,303 ****
--- 290,309 ----
    // Grow the output array to the next larger power-of-2 bigger than len.
    void out_grow( uint len );
  
   public:
    // Each Node is assigned a unique small/dense number.  This number is used
!   // to index into auxiliary arrays of data and bit vectors.
!   // It is declared const to defend against inadvertant assignment,
!   // since it is used by clients as a naked field.
!   // The field _idx is declared constant to defend against inadvertent assignments,
!   // since it is used by clients as a naked field. However, the field's value can be
+   // changed using the set_idx() method.
+   //
+   // The PhaseRenumberLive phase renumbers nodes based on liveness information.
+   // Therefore, it updates the value of the _idx field. The parse-time _idx is
+   // preserved in _parse_idx.
    const node_idx_t _idx;
+   DEBUG_ONLY(const node_idx_t _parse_idx;)
  
    // Get the (read-only) number of input edges
    uint req() const { return _cnt; }
    uint len() const { return _max; }
    // Get the (read-only) number of output edges