src/share/vm/opto/matcher.cpp

*** 878,888 ****
        // Monitor boxes are also represented directly.
        for (i = cnt - 1; i >= debug_cnt; --i) { // For all debug inputs do
          Node *m = n->in(i);          // Get input
          int op = m->Opcode();
          assert((op == Op_BoxLock) == jvms->is_monitor_use(i), "boxes only at monitor sites");
!         if( op == Op_ConI || op == Op_ConP ||
              op == Op_ConF || op == Op_ConD || op == Op_ConL
              // || op == Op_BoxLock  // %%%% enable this and remove (+++) in chaitin.cpp
              ) {
            m = m->clone();
            mstack.push(m, Post_Visit, n, i); // Don't neet to visit
--- 878,888 ----
        // Monitor boxes are also represented directly.
        for (i = cnt - 1; i >= debug_cnt; --i) { // For all debug inputs do
          Node *m = n->in(i);          // Get input
          int op = m->Opcode();
          assert((op == Op_BoxLock) == jvms->is_monitor_use(i), "boxes only at monitor sites");
!         if( op == Op_ConI || op == Op_ConP || op == Op_ConN ||
              op == Op_ConF || op == Op_ConD || op == Op_ConL
              // || op == Op_BoxLock  // %%%% enable this and remove (+++) in chaitin.cpp
              ) {
            m = m->clone();
            mstack.push(m, Post_Visit, n, i); // Don't neet to visit
*** 1723,1732 ****
--- 1723,1740 ----
          const TypePtr* tp = tn->type()->is_ptr();
          if (tp->_ptr == TypePtr::AnyNull) {
            tn->set_type(TypePtr::NULL_PTR);
          }
          break;
+       }
+       case Op_ConN: {  // Convert narrow pointers above the centerline to NUL
+         TypeNode *tn = n->as_Type(); // Constants derive from type nodes
+         const TypePtr* tp = tn->type()->is_narrowoop()->make_oopptr();
+         if (tp->_ptr == TypePtr::AnyNull) {
+           tn->set_type(TypeNarrowOop::NULL_PTR);
+         }
+         break;
        }
        case Op_Binary:         // These are introduced in the Post_Visit state.
          ShouldNotReachHere();
          break;
        case Op_StoreB:         // Do match these, despite no ideal reg