/*

 * Copyright (c) 1998, 2019, 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_RUNTIME_BASICLOCK_HPP

#define SHARE_RUNTIME_BASICLOCK_HPP

#include "oops/markWord.hpp"

#include "runtime/atomic.hpp"

#include "runtime/handles.hpp"

class BasicLock {

  friend class VMStructs;

  friend class JVMCIVMStructs;

 private:

  volatile markWord _displaced_header;

 public:

  markWord displaced_header() const {

    return Atomic::load(&_displaced_header);

  }

  void set_displaced_header(markWord header) {

    Atomic::store(header, &_displaced_header);

  }

  void print_on(outputStream* st) const;

  // move a basic lock (used during deoptimization

  void move_to(oop obj, BasicLock* dest);

  static int displaced_header_offset_in_bytes()       { return offset_of(BasicLock, _displaced_header); }

};

// A BasicObjectLock associates a specific Java object with a BasicLock.

// It is currently embedded in an interpreter frame.

// Because some machines have alignment restrictions on the control stack,

// the actual space allocated by the interpreter may include padding words

// after the end of the BasicObjectLock.  Also, in order to guarantee

// alignment of the embedded BasicLock objects on such machines, we

// put the embedded BasicLock at the beginning of the struct.

class BasicObjectLock {

  friend class VMStructs;

 private:

  BasicLock _lock;                                    // the lock, must be double word aligned

  oop       _obj;                                     // object holds the lock;

 public:

  // Manipulation

  oop      obj() const                                { return _obj;  }

  void set_obj(oop obj)                               { _obj = obj; }

  BasicLock* lock()                                   { return &_lock; }

  // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks

  //       in interpreter activation frames since it includes machine-specific padding.

  static int size()                                   { return sizeof(BasicObjectLock)/wordSize; }

  // GC support

  void oops_do(OopClosure* f) { f->do_oop(&_obj); }

  static int obj_offset_in_bytes()                    { return offset_of(BasicObjectLock, _obj);  }

  static int lock_offset_in_bytes()                   { return offset_of(BasicObjectLock, _lock); }

};

#endif // SHARE_RUNTIME_BASICLOCK_HPP