/*

 * 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

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 * 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