1 /*
   2  * Copyright (c) 2011, 2013, 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
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP
  26 #define SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP
  27 
  28 #include "classfile/systemDictionary.hpp"
  29 #include "oops/instanceKlass.hpp"
  30 #include "runtime/handles.hpp"
  31 #include "utilities/macros.hpp"
  32 
  33 // An InstanceMirrorKlass is a specialized InstanceKlass for
  34 // java.lang.Class instances.  These instances are special because
  35 // they contain the static fields of the class in addition to the
  36 // normal fields of Class.  This means they are variable sized
  37 // instances and need special logic for computing their size and for
  38 // iteration of their oops.
  39 
  40 
  41 class InstanceMirrorKlass: public InstanceKlass {
  42   friend class VMStructs;
  43   friend class InstanceKlass;
  44 
  45  private:
  46   static int _offset_of_static_fields;
  47 
  48   // Constructor
  49   InstanceMirrorKlass(int vtable_len, int itable_len, int static_field_size, int nonstatic_oop_map_size, ReferenceType rt, AccessFlags access_flags,  bool is_anonymous);
  50 
  51  public:
  52   InstanceMirrorKlass() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }
  53   // Type testing
  54   bool oop_is_instanceMirror() const             { return true; }
  55 
  56   // Casting from Klass*
  57   static InstanceMirrorKlass* cast(Klass* k) {
  58     assert(k->oop_is_instanceMirror(), "cast to InstanceMirrorKlass");
  59     return (InstanceMirrorKlass*) k;
  60   }
  61 
  62   // Returns the size of the instance including the extra static fields.
  63   virtual int oop_size(oop obj) const;
  64 
  65   // Static field offset is an offset into the Heap, should be converted by
  66   // based on UseCompressedOop for traversal
  67   static HeapWord* start_of_static_fields(oop obj) {
  68     return (HeapWord*)(cast_from_oop<intptr_t>(obj) + offset_of_static_fields());
  69   }
  70 
  71   static void init_offset_of_static_fields() {
  72     // Cache the offset of the static fields in the Class instance
  73     assert(_offset_of_static_fields == 0, "once");
  74     _offset_of_static_fields = InstanceMirrorKlass::cast(SystemDictionary::Class_klass())->size_helper() << LogHeapWordSize;
  75   }
  76 
  77   static int offset_of_static_fields() {
  78     return _offset_of_static_fields;
  79   }
  80 
  81   int compute_static_oop_field_count(oop obj);
  82 
  83   // Given a Klass return the size of the instance
  84   int instance_size(KlassHandle k);
  85 
  86   // allocation
  87   instanceOop allocate_instance(KlassHandle k, TRAPS);
  88 
  89   // Garbage collection
  90   int  oop_adjust_pointers(oop obj);
  91   void oop_follow_contents(oop obj);
  92 
  93   // Parallel Scavenge and Parallel Old
  94   PARALLEL_GC_DECLS
  95 
  96  template <bool nv, typename OopClosureType>
  97  int oop_oop_iterate(oop obj, OopClosureType* blk);
  98 
  99  template <bool nv, typename OopClosureType>
 100  int oop_oop_iterate_m(oop obj, OopClosureType* blk, MemRegion mr);
 101 
 102 #if INCLUDE_ALL_GCS
 103  template <bool nv, typename OopClosureType>
 104  int oop_oop_iterate_backwards(oop obj, OopClosureType* blk);
 105 #endif // INCLUDE_ALL_GCS
 106 };
 107 
 108 #endif // SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP