jdk-24/hotspot/src/share/vm/oops/instanceMirrorKlass.hpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#ifndef SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP
#define SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP

#include "classfile/systemDictionary.hpp"
#include "oops/instanceKlass.hpp"
#include "runtime/handles.hpp"

// An instanceMirrorKlass is a specialized InstanceKlass for
// java.lang.Class instances.  These instances are special because
// they contain the static fields of the class in addition to the
// normal fields of Class.  This means they are variable sized
// instances and need special logic for computing their size and for
// iteration of their oops.


class instanceMirrorKlass: public InstanceKlass {
  friend class VMStructs;
  friend class InstanceKlass;

 private:
  static int _offset_of_static_fields;

  // Constructor
  instanceMirrorKlass(int vtable_len, int itable_len, int static_field_size, int nonstatic_oop_map_size, ReferenceType rt, AccessFlags access_flags,  bool is_anonymous)
    : InstanceKlass(vtable_len, itable_len, static_field_size, nonstatic_oop_map_size, rt, access_flags, is_anonymous) {}

 public:
  instanceMirrorKlass() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); }
  // Type testing
  bool oop_is_instanceMirror() const             { return true; }

  // Casting from Klass*
  static instanceMirrorKlass* cast(Klass* k) {
    assert(k->oop_is_instanceMirror(), "cast to instanceMirrorKlass");
    return (instanceMirrorKlass*) k;
  }

  // Returns the size of the instance including the extra static fields.
  virtual int oop_size(oop obj) const;

  // Static field offset is an offset into the Heap, should be converted by
  // based on UseCompressedOop for traversal
  static HeapWord* start_of_static_fields(oop obj) {
    return (HeapWord*)((intptr_t)obj + offset_of_static_fields());
  }

  static void init_offset_of_static_fields() {
    // Cache the offset of the static fields in the Class instance
    assert(_offset_of_static_fields == 0, "once");
    _offset_of_static_fields = instanceMirrorKlass::cast(SystemDictionary::Class_klass())->size_helper() << LogHeapWordSize;
  }

  static int offset_of_static_fields() {
    return _offset_of_static_fields;
  }

  int compute_static_oop_field_count(oop obj);

  // Given a Klass return the size of the instance
  int instance_size(KlassHandle k);

  // allocation
  instanceOop allocate_instance(KlassHandle k, TRAPS);

  // Garbage collection
  int  oop_adjust_pointers(oop obj);
  void oop_follow_contents(oop obj);

  // Parallel Scavenge and Parallel Old
  PARALLEL_GC_DECLS

  int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) {
    return oop_oop_iterate_v(obj, blk);
  }
  int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
    return oop_oop_iterate_v_m(obj, blk, mr);
  }

#define InstanceMirrorKlass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)           \
  int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk);                       \
  int oop_oop_iterate##nv_suffix##_m(oop obj, OopClosureType* blk, MemRegion mr);

  ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceMirrorKlass_OOP_OOP_ITERATE_DECL)
  ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceMirrorKlass_OOP_OOP_ITERATE_DECL)

#ifndef SERIALGC
#define InstanceMirrorKlass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix) \
  int oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* blk);

  ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceMirrorKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
  ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceMirrorKlass_OOP_OOP_ITERATE_BACKWARDS_DECL)
#endif // !SERIALGC
};

#endif // SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP