hotspot/src/share/vm/oops/instanceOop.hpp
author coleenp
Sun, 13 Apr 2008 17:43:42 -0400
changeset 360 21d113ecbf6a
parent 1 489c9b5090e2
child 591 04d2e26e6d69
permissions -rw-r--r--
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold

/*
 * Copyright 1997-2000 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 */

// An instanceOop is an instance of a Java Class
// Evaluating "new HashTable()" will create an instanceOop.

class instanceOopDesc : public oopDesc {
 public:
  // aligned header size.
  static int header_size() { return sizeof(instanceOopDesc)/HeapWordSize; }

  // If compressed, the offset of the fields of the instance may not be aligned.
  static int base_offset_in_bytes() {
    return UseCompressedOops ?
             klass_gap_offset_in_bytes() :
             sizeof(instanceOopDesc);
  }

  static bool contains_field_offset(int offset, int nonstatic_field_size) {
    int base_in_bytes = base_offset_in_bytes();
    if (UseCompressedOops) {
      return (offset >= base_in_bytes &&
              // field can be embedded in header, or is after header.
              (offset < (int)sizeof(instanceOopDesc) ||
              (offset-(int)sizeof(instanceOopDesc))/wordSize < nonstatic_field_size));
    } else {
      return (offset >= base_in_bytes &&
              (offset-base_in_bytes)/wordSize < nonstatic_field_size);
    }
  }
};