text: /*
   * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   *
   */
  
  #ifndef SHARE_VM_OPTO_REPLACEDNODES_HPP
  #define SHARE_VM_OPTO_REPLACEDNODES_HPP
  
  #include "opto/connode.hpp"
  
  // During parsing, when a node is "improved",
  // GraphKit::replace_in_map() is called to update the current map so
  // that the improved node is used from that point
  // on. GraphKit::replace_in_map() doesn't operate on the callers maps
  // and so some optimization opportunities may be lost. The
  // ReplacedNodes class addresses that problem.
  //
  // A ReplacedNodes object is a list of pair of nodes. Every
  // SafePointNode carries a ReplacedNodes object. Every time
  // GraphKit::replace_in_map() is called, a new pair of nodes is pushed
  // on the list of replaced nodes. When control flow paths merge, their
  // replaced nodes are also merged. When parsing exits a method to
  // return to a caller, the replaced nodes on the exit path are used to
  // update the caller's map.
  class ReplacedNodes {
   private:
    class ReplacedNode {
    private:
      Node* _initial;
      Node* _improved;
    public:
      ReplacedNode() : _initial(NULL), _improved(NULL) {}
      ReplacedNode(Node* initial, Node* improved) : _initial(initial), _improved(improved) {}
      Node* initial() const  { return _initial; }
      Node* improved() const { return _improved; }
  
      bool operator==(const ReplacedNode& other) {
        return _initial == other._initial && _improved == other._improved;
      }
    };
    GrowableArray<ReplacedNode>* _replaced_nodes;
  
    void allocate_if_necessary();
    bool has_node(const ReplacedNode& r) const;
    bool has_target_node(Node* n) const;
  
   public:
    ReplacedNodes()
      : _replaced_nodes(NULL) {}
  
    void clone();
    void record(Node* initial, Node* improved);
    void transfer_from(const ReplacedNodes& other, uint idx);
    void reset();
    void apply(Node* n, uint idx);
    void merge_with(const ReplacedNodes& other);
    bool is_empty() const;
    void dump(outputStream *st) const;
    void apply(Compile* C, Node* ctl);
  };
  
  #endif // SHARE_VM_OPTO_REPLACEDNODES_HPP
  