Java example source code file (klass.inline.hpp)

This example Java source code file (klass.inline.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

address, const64, java, klass, klass::is_null, klass\*, klass\:\:decode_klass, klass\:\:encode_klass, klass\:\:set_prototype_header, klassalignmentinbytes, ptr_format, share_vm_oops_klass_inline_hpp, universe::narrow_klass_shift, universe\:\:narrow_klass_base

The klass.inline.hpp Java example source code

/*
 * Copyright (c) 2005, 2013, 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_KLASS_INLINE_HPP
#define SHARE_VM_OOPS_KLASS_INLINE_HPP

#include "memory/universe.hpp"
#include "oops/klass.hpp"
#include "oops/markOop.hpp"

inline void Klass::set_prototype_header(markOop header) {
  assert(!header->has_bias_pattern() || oop_is_instance(), "biased locking currently only supported for Java instances");
  _prototype_header = header;
}

inline bool Klass::is_null(Klass* obj)  { return obj == NULL; }
inline bool Klass::is_null(narrowKlass obj) { return obj == 0; }

// Encoding and decoding for klass field.

inline bool check_klass_alignment(Klass* obj) {
  return (intptr_t)obj % KlassAlignmentInBytes == 0;
}

inline narrowKlass Klass::encode_klass_not_null(Klass* v) {
  assert(!is_null(v), "klass value can never be zero");
  assert(check_klass_alignment(v), "Address not aligned");
  int    shift = Universe::narrow_klass_shift();
  uint64_t pd = (uint64_t)(pointer_delta((void*)v, Universe::narrow_klass_base(), 1));
  assert(KlassEncodingMetaspaceMax > pd, "change encoding max if new encoding");
  uint64_t result = pd >> shift;
  assert((result & CONST64(0xffffffff00000000)) == 0, "narrow klass pointer overflow");
  assert(decode_klass(result) == v, "reversibility");
  return (narrowKlass)result;
}

inline narrowKlass Klass::encode_klass(Klass* v) {
  return is_null(v) ? (narrowKlass)0 : encode_klass_not_null(v);
}

inline Klass* Klass::decode_klass_not_null(narrowKlass v) {
  assert(!is_null(v), "narrow klass value can never be zero");
  int    shift = Universe::narrow_klass_shift();
  Klass* result = (Klass*)(void*)((uintptr_t)Universe::narrow_klass_base() + ((uintptr_t)v << shift));
  assert(check_klass_alignment(result), err_msg("address not aligned: " PTR_FORMAT, (void*) result));
  return result;
}

inline Klass* Klass::decode_klass(narrowKlass v) {
  return is_null(v) ? (Klass*)NULL : decode_klass_not_null(v);
}

#endif // SHARE_VM_OOPS_KLASS_INLINE_HPP