1 /*
   2  * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  23  */
  24 
  25 #ifndef SHARE_OOPS_INSTANCEOOP_HPP
  26 #define SHARE_OOPS_INSTANCEOOP_HPP
  27 
  28 #include "oops/oop.hpp"
  29 
  30 // An instanceOop is an instance of a Java Class
  31 // Evaluating "new HashTable()" will create an instanceOop.
  32 
  33 class instanceOopDesc : public oopDesc {
  34  public:
  35   // aligned header size.
  36   static int header_size() { return sizeof(instanceOopDesc)/HeapWordSize; }
  37 
  38   // If compressed, the offset of the fields of the instance may not be aligned.
  39   static int base_offset_in_bytes() {
  40     // offset computation code breaks if UseCompressedClassPointers
  41     // only is true
  42     return (UseCompressedOops && UseCompressedClassPointers) ?
  43              klass_gap_offset_in_bytes() :
  44              sizeof(instanceOopDesc);
  45   }
  46 
  47   static bool contains_field_offset(int offset, int nonstatic_field_size) {
  48     int base_in_bytes = base_offset_in_bytes();
  49     return (offset >= base_in_bytes &&
  50             (offset-base_in_bytes) < nonstatic_field_size * heapOopSize);
  51   }
  52 };
  53 
  54 #endif // SHARE_OOPS_INSTANCEOOP_HPP