1 /*
   2  * Copyright (c) 2011, 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 "oops/instanceKlass.hpp"
  29 
  30 // An instanceMirrorKlass is a specialized instanceKlass for
  31 // java.lang.Class instances.  These instances are special because
  32 // they contain the static fields of the class in addition to the
  33 // normal fields of Class.  This means they are variable sized
  34 // instances and need special logic for computing their size and for
  35 // iteration of their oops.
  36 
  37 
  38 class instanceMirrorKlass: public instanceKlass {
  39   friend class VMStructs;
  40 
  41  private:
  42   static int _offset_of_static_fields;
  43 
  44  public:
  45   // Type testing
  46   bool oop_is_instanceMirror() const             { return true; }
  47 
  48   // Casting from klassOop
  49   static instanceMirrorKlass* cast(klassOop k) {
  50     assert(k->klass_part()->oop_is_instanceMirror(), "cast to instanceMirrorKlass");
  51     return (instanceMirrorKlass*) k->klass_part();
  52   }
  53 
  54   // Returns the size of the instance including the extra static fields.
  55   virtual int oop_size(oop obj) const;
  56 
  57   // Static field offset is an offset into the Heap, should be converted by
  58   // based on UseCompressedOop for traversal
  59   static HeapWord* start_of_static_fields(oop obj) {
  60     return (HeapWord*)((intptr_t)obj + offset_of_static_fields());
  61   }
  62 
  63   static void init_offset_of_static_fields() {
  64     // Cache the offset of the static fields in the Class instance
  65     assert(_offset_of_static_fields == 0, "once");
  66     _offset_of_static_fields = instanceMirrorKlass::cast(SystemDictionary::Class_klass())->size_helper() << LogHeapWordSize;
  67   }
  68 
  69   static int offset_of_static_fields() {
  70     return _offset_of_static_fields;
  71   }
  72 
  73   int compute_static_oop_field_count(oop obj);
  74 
  75   // Given a Klass return the size of the instance
  76   int instance_size(KlassHandle k);
  77 
  78   // allocation
  79   DEFINE_ALLOCATE_PERMANENT(instanceMirrorKlass);
  80   instanceOop allocate_instance(KlassHandle k, TRAPS);
  81 
  82   // Garbage collection
  83   int  oop_adjust_pointers(oop obj);
  84   void oop_follow_contents(oop obj);
  85 
  86   // Parallel Scavenge and Parallel Old
  87   PARALLEL_GC_DECLS
  88 
  89   int oop_oop_iterate(oop obj, OopClosure* blk) {
  90     return oop_oop_iterate_v(obj, blk);
  91   }
  92   int oop_oop_iterate_m(oop obj, OopClosure* blk, MemRegion mr) {
  93     return oop_oop_iterate_v_m(obj, blk, mr);
  94   }
  95 
  96 #define InstanceMirrorKlass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)           \
  97   int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk);                       \
  98   int oop_oop_iterate##nv_suffix##_m(oop obj, OopClosureType* blk, MemRegion mr);
  99 
 100   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceMirrorKlass_OOP_OOP_ITERATE_DECL)
 101   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceMirrorKlass_OOP_OOP_ITERATE_DECL)
 102 
 103 #ifndef SERIALGC
 104 #define InstanceMirrorKlass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
 105   int oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* blk);
 106 
 107   ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceMirrorKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 108   ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceMirrorKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 109 #endif // !SERIALGC
 110 };
 111 
 112 #endif // SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP