/*

 * Copyright (c) 1997, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "classfile/javaClasses.hpp"

#include "classfile/systemDictionary.hpp"

#include "oops/instanceRefKlass.inline.hpp"

#include "oops/oop.inline.hpp"

void InstanceRefKlass::update_nonstatic_oop_maps(Klass* k) {

  // Clear the nonstatic oop-map entries corresponding to referent

  // and discovered fields.  They are treated specially by the

  // garbage collector.

  InstanceKlass* ik = InstanceKlass::cast(k);

  // Check that we have the right class

  debug_only(static bool first_time = true);

  assert(k == SystemDictionary::Reference_klass() && first_time,

         "Invalid update of maps");

  debug_only(first_time = false);

  assert(ik->nonstatic_oop_map_count() == 1, "just checking");

  OopMapBlock* map = ik->start_of_nonstatic_oop_maps();

#ifdef ASSERT

  // Verify fields are in the expected places.

  int referent_offset = java_lang_ref_Reference::referent_offset;

  int queue_offset = java_lang_ref_Reference::queue_offset;

  int next_offset = java_lang_ref_Reference::next_offset;

  int discovered_offset = java_lang_ref_Reference::discovered_offset;

  assert(referent_offset < queue_offset, "just checking");

  assert(queue_offset < next_offset, "just checking");

  assert(next_offset < discovered_offset, "just checking");

  const unsigned int count =

    1 + ((discovered_offset - referent_offset) / heapOopSize);

  assert(count == 4, "just checking");

#endif // ASSERT

  // Updated map starts at "queue", covers "queue" and "next".

  const int new_offset = java_lang_ref_Reference::queue_offset;

  const unsigned int new_count = 2; // queue and next

  // Verify existing map is as expected, and update if needed.

  if (UseSharedSpaces) {

    assert(map->offset() == new_offset, "just checking");

    assert(map->count() == new_count, "just checking");

  } else {

    assert(map->offset() == referent_offset, "just checking");

    assert(map->count() == count, "just checking");

    map->set_offset(new_offset);

    map->set_count(new_count);

  }

}

// Verification

void InstanceRefKlass::oop_verify_on(oop obj, outputStream* st) {

  InstanceKlass::oop_verify_on(obj, st);

  // Verify referent field

  oop referent = java_lang_ref_Reference::referent(obj);

  if (referent != NULL) {

    guarantee(oopDesc::is_oop(referent), "referent field heap failed");

  }

  // Additional verification for next field, which must be a Reference or null

  oop next = java_lang_ref_Reference::next(obj);

  if (next != NULL) {

    guarantee(oopDesc::is_oop(next), "next field should be an oop");

    guarantee(next->is_instance(), "next field should be an instance");

    guarantee(InstanceKlass::cast(next->klass())->is_reference_instance_klass(), "next field verify failed");

  }

}