/*

 * Copyright (c) 1998, 2012, 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_OOPS_COMPILEDICHOLDEROOP_HPP

#define SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP

#include "oops/oop.hpp"

// A CompiledICHolder* is a helper object for the inline cache implementation.

// It holds an intermediate value (method+klass pair) used when converting from

// compiled to an interpreted call.

//

// These are always allocated in the C heap and are freed during a

// safepoint by the ICBuffer logic.  It's unsafe to free them earlier

// since they might be in use.

//

class CompiledICHolder : public CHeapObj<mtCompiler> {

  friend class VMStructs;

 private:

  static volatile int _live_count; // allocated

  static volatile int _live_not_claimed_count; // allocated but not yet in use so not

                                               // reachable by iterating over nmethods

  Method* _holder_method;

  Klass*    _holder_klass;    // to avoid name conflict with oopDesc::_klass

  CompiledICHolder* _next;

 public:

  // Constructor

  CompiledICHolder(Method* method, Klass* klass)

      : _holder_method(method), _holder_klass(klass) {

#ifdef ASSERT

    Atomic::inc(&_live_count);

    Atomic::inc(&_live_not_claimed_count);

#endif

  }

  ~CompiledICHolder() {

#ifdef ASSERT

    assert(_live_count > 0, "underflow");

    Atomic::dec(&_live_count);

#endif

  }

  static int live_count() { return _live_count; }

  static int live_not_claimed_count() { return _live_not_claimed_count; }

  // accessors

  Method* holder_method() const     { return _holder_method; }

  Klass*    holder_klass()  const     { return _holder_klass; }

  void set_holder_method(Method* m) { _holder_method = m; }

  void set_holder_klass(Klass* k)   { _holder_klass = k; }

  // interpreter support (offsets in bytes)

  static int holder_method_offset()   { return offset_of(CompiledICHolder, _holder_method); }

  static int holder_klass_offset()    { return offset_of(CompiledICHolder, _holder_klass); }

  CompiledICHolder* next()     { return _next; }

  void set_next(CompiledICHolder* n) { _next = n; }

  // Verify

  void verify_on(outputStream* st);

  // Printing

  void print_on(outputStream* st) const;

  void print_value_on(outputStream* st) const;

  const char* internal_name() const { return "{compiledICHolder}"; }

  void claim() {

#ifdef ASSERT

    Atomic::dec(&_live_not_claimed_count);

#endif

  }

};

#endif // SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP