/*

 * Copyright (c) 2014, 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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 */

#ifndef SHARE_VM_OPTO_OPAQUENODE_HPP

#define SHARE_VM_OPTO_OPAQUENODE_HPP

#include "opto/node.hpp"

#include "opto/opcodes.hpp"

//------------------------------Opaque1Node------------------------------------

// A node to prevent unwanted optimizations.  Allows constant folding.

// Stops value-numbering, Ideal calls or Identity functions.

class Opaque1Node : public Node {

  virtual uint hash() const ;                  // { return NO_HASH; }

  virtual uint cmp( const Node &n ) const;

  public:

  Opaque1Node( Compile* C, Node *n ) : Node(0,n) {

    // Put it on the Macro nodes list to removed during macro nodes expansion.

    init_flags(Flag_is_macro);

    C->add_macro_node(this);

  }

  // Special version for the pre-loop to hold the original loop limit

  // which is consumed by range check elimination.

  Opaque1Node( Compile* C, Node *n, Node* orig_limit ) : Node(0,n,orig_limit) {

    // Put it on the Macro nodes list to removed during macro nodes expansion.

    init_flags(Flag_is_macro);

    C->add_macro_node(this);

  }

  Node* original_loop_limit() { return req()==3 ? in(2) : NULL; }

  virtual int Opcode() const;

  virtual const Type *bottom_type() const { return TypeInt::INT; }

  virtual Node *Identity( PhaseTransform *phase );

};

//------------------------------Opaque2Node------------------------------------

// A node to prevent unwanted optimizations.  Allows constant folding.  Stops

// value-numbering, most Ideal calls or Identity functions.  This Node is

// specifically designed to prevent the pre-increment value of a loop trip

// counter from being live out of the bottom of the loop (hence causing the

// pre- and post-increment values both being live and thus requiring an extra

// temp register and an extra move).  If we "accidentally" optimize through

// this kind of a Node, we'll get slightly pessimal, but correct, code.  Thus

// it's OK to be slightly sloppy on optimizations here.

class Opaque2Node : public Node {

  virtual uint hash() const ;                  // { return NO_HASH; }

  virtual uint cmp( const Node &n ) const;

  public:

  Opaque2Node( Compile* C, Node *n ) : Node(0,n) {

    // Put it on the Macro nodes list to removed during macro nodes expansion.

    init_flags(Flag_is_macro);

    C->add_macro_node(this);

  }

  virtual int Opcode() const;

  virtual const Type *bottom_type() const { return TypeInt::INT; }

};

//------------------------------Opaque3Node------------------------------------

// A node to prevent unwanted optimizations. Will be optimized only during

// macro nodes expansion.

class Opaque3Node : public Opaque2Node {

  int _opt; // what optimization it was used for

  public:

  enum { RTM_OPT };

  Opaque3Node(Compile* C, Node *n, int opt) : Opaque2Node(C, n), _opt(opt) {}

  virtual int Opcode() const;

  bool rtm_opt() const { return (_opt == RTM_OPT); }

};

#endif // SHARE_VM_OPTO_OPAQUENODE_HPP