/*

 * Copyright (c) 2003, 2005, Oracle and/or its affiliates. All rights reserved.

 * Copyright 2007, 2008, 2010 Red Hat, Inc.

 * 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.

 *

 */

 private:

  ZeroFrame* volatile _last_Java_fp;

 public:

  // Each arch must define reset, save, restore

  // These are used by objects that only care about:

  //  1 - initializing a new state (thread creation, javaCalls)

  //  2 - saving a current state (javaCalls)

  //  3 - restoring an old state (javaCalls)

  // Note that whenever _last_Java_sp != NULL other anchor fields

  // must be valid.  The profiler apparently depends on this.

  void clear() {

    // clearing _last_Java_sp must be first

    _last_Java_sp = NULL;

    // fence?

    _last_Java_fp = NULL;

    _last_Java_pc = NULL;

  }

  void copy(JavaFrameAnchor* src) {

    set(src->_last_Java_sp, src->_last_Java_pc, src->_last_Java_fp);

  }

  void set(intptr_t* sp, address pc, ZeroFrame* fp) {

    // In order to make sure the transition state is valid for "this"

    // We must clear _last_Java_sp before copying the rest of the new

    // data

    //

    // Hack Alert: Temporary bugfix for 4717480/4721647 To act like

    // previous version (pd_cache_state) don't NULL _last_Java_sp

    // unless the value is changing

    //

    if (_last_Java_sp != sp)

      _last_Java_sp = NULL;

    _last_Java_fp = fp;

    _last_Java_pc = pc;

    // Must be last so profiler will always see valid frame if

    // has_last_frame() is true

    _last_Java_sp = sp;

  }

  bool walkable() {

    return true;

  }

  void make_walkable(JavaThread* thread) {

    // nothing to do

  }

  intptr_t* last_Java_sp() const {

    return _last_Java_sp;

  }

  ZeroFrame* last_Java_fp() const {

    return _last_Java_fp;

  }

  static ByteSize last_Java_fp_offset() {

    return byte_offset_of(JavaFrameAnchor, _last_Java_fp);

  }