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Java example source code file (klass.hpp)

This example Java source code file (klass.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

array, basictype, bytesize, classloaderdata, extendedoopclosure, include_all_gcs, klass, memregion, null, oopclosuretype, share_vm_oops_klass_hpp, specialized_oop_oop_iterate_closures_1, symbol, traps

The klass.hpp Java example source code

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_OOPS_KLASS_HPP
#define SHARE_VM_OOPS_KLASS_HPP

#include "memory/genOopClosures.hpp"
#include "memory/iterator.hpp"
#include "memory/memRegion.hpp"
#include "memory/specialized_oop_closures.hpp"
#include "oops/klassPS.hpp"
#include "oops/metadata.hpp"
#include "oops/oop.hpp"
#include "runtime/orderAccess.hpp"
#include "trace/traceMacros.hpp"
#include "utilities/accessFlags.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_ALL_GCS
#include "gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp"
#include "gc_implementation/g1/g1OopClosures.hpp"
#include "gc_implementation/parNew/parOopClosures.hpp"
#endif // INCLUDE_ALL_GCS

//
// A Klass provides:
//  1: language level class object (method dictionary etc.)
//  2: provide vm dispatch behavior for the object
// Both functions are combined into one C++ class.

// One reason for the oop/klass dichotomy in the implementation is
// that we don't want a C++ vtbl pointer in every object.  Thus,
// normal oops don't have any virtual functions.  Instead, they
// forward all "virtual" functions to their klass, which does have
// a vtbl and does the C++ dispatch depending on the object's
// actual type.  (See oop.inline.hpp for some of the forwarding code.)
// ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!

//  Klass layout:
//    [C++ vtbl ptr  ] (contained in Metadata)
//    [layout_helper ]
//    [super_check_offset   ] for fast subtype checks
//    [name          ]
//    [secondary_super_cache] for fast subtype checks
//    [secondary_supers     ] array of 2ndary supertypes
//    [primary_supers 0]
//    [primary_supers 1]
//    [primary_supers 2]
//    ...
//    [primary_supers 7]
//    [java_mirror   ]
//    [super         ]
//    [subklass      ] first subclass
//    [next_sibling  ] link to chain additional subklasses
//    [next_link     ]
//    [class_loader_data]
//    [modifier_flags]
//    [access_flags  ]
//    [last_biased_lock_bulk_revocation_time] (64 bits)
//    [prototype_header]
//    [biased_lock_revocation_count]
//    [_modified_oops]
//    [_accumulated_modified_oops]
//    [trace_id]


// Forward declarations.
template <class T> class Array;
template <class T> class GrowableArray;
class ClassLoaderData;
class klassVtable;
class ParCompactionManager;
class KlassSizeStats;

class Klass : public Metadata {
  friend class VMStructs;
 protected:
  // note: put frequently-used fields together at start of klass structure
  // for better cache behavior (may not make much of a difference but sure won't hurt)
  enum { _primary_super_limit = 8 };

  // The "layout helper" is a combined descriptor of object layout.
  // For klasses which are neither instance nor array, the value is zero.
  //
  // For instances, layout helper is a positive number, the instance size.
  // This size is already passed through align_object_size and scaled to bytes.
  // The low order bit is set if instances of this class cannot be
  // allocated using the fastpath.
  //
  // For arrays, layout helper is a negative number, containing four
  // distinct bytes, as follows:
  //    MSB:[tag, hsz, ebt, log2(esz)]:LSB
  // where:
  //    tag is 0x80 if the elements are oops, 0xC0 if non-oops
  //    hsz is array header size in bytes (i.e., offset of first element)
  //    ebt is the BasicType of the elements
  //    esz is the element size in bytes
  // This packed word is arranged so as to be quickly unpacked by the
  // various fast paths that use the various subfields.
  //
  // The esz bits can be used directly by a SLL instruction, without masking.
  //
  // Note that the array-kind tag looks like 0x00 for instance klasses,
  // since their length in bytes is always less than 24Mb.
  //
  // Final note:  This comes first, immediately after C++ vtable,
  // because it is frequently queried.
  jint        _layout_helper;

  // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
  // and _primary_supers all help make fast subtype checks.  See big discussion
  // in doc/server_compiler/checktype.txt
  //
  // Where to look to observe a supertype (it is &_secondary_super_cache for
  // secondary supers, else is &_primary_supers[depth()].
  juint       _super_check_offset;

  // Class name.  Instance classes: java/lang/String, etc.  Array classes: [I,
  // [Ljava/lang/String;, etc.  Set to zero for all other kinds of classes.
  Symbol*     _name;

  // Cache of last observed secondary supertype
  Klass*      _secondary_super_cache;
  // Array of all secondary supertypes
  Array<Klass*>* _secondary_supers;
  // Ordered list of all primary supertypes
  Klass*      _primary_supers[_primary_super_limit];
  // java/lang/Class instance mirroring this class
  oop       _java_mirror;
  // Superclass
  Klass*      _super;
  // First subclass (NULL if none); _subklass->next_sibling() is next one
  Klass*      _subklass;
  // Sibling link (or NULL); links all subklasses of a klass
  Klass*      _next_sibling;

  // All klasses loaded by a class loader are chained through these links
  Klass*      _next_link;

  // The VM's representation of the ClassLoader used to load this class.
  // Provide access the corresponding instance java.lang.ClassLoader.
  ClassLoaderData* _class_loader_data;

  jint        _modifier_flags;  // Processed access flags, for use by Class.getModifiers.
  AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.

  // Biased locking implementation and statistics
  // (the 64-bit chunk goes first, to avoid some fragmentation)
  jlong    _last_biased_lock_bulk_revocation_time;
  markOop  _prototype_header;   // Used when biased locking is both enabled and disabled for this type
  jint     _biased_lock_revocation_count;

  TRACE_DEFINE_KLASS_TRACE_ID;

  // Remembered sets support for the oops in the klasses.
  jbyte _modified_oops;             // Card Table Equivalent (YC/CMS support)
  jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)

  // Constructor
  Klass();

  void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();

 public:
  bool is_klass() const volatile { return true; }

  // super
  Klass* super() const               { return _super; }
  void set_super(Klass* k)           { _super = k; }

  // initializes _super link, _primary_supers & _secondary_supers arrays
  void initialize_supers(Klass* k, TRAPS);
  void initialize_supers_impl1(Klass* k);
  void initialize_supers_impl2(Klass* k);

  // klass-specific helper for initializing _secondary_supers
  virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);

  // java_super is the Java-level super type as specified by Class.getSuperClass.
  virtual Klass* java_super() const  { return NULL; }

  juint    super_check_offset() const  { return _super_check_offset; }
  void set_super_check_offset(juint o) { _super_check_offset = o; }

  Klass* secondary_super_cache() const     { return _secondary_super_cache; }
  void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }

  Array<Klass*>* secondary_supers() const { return _secondary_supers; }
  void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }

  // Return the element of the _super chain of the given depth.
  // If there is no such element, return either NULL or this.
  Klass* primary_super_of_depth(juint i) const {
    assert(i < primary_super_limit(), "oob");
    Klass* super = _primary_supers[i];
    assert(super == NULL || super->super_depth() == i, "correct display");
    return super;
  }

  // Can this klass be a primary super?  False for interfaces and arrays of
  // interfaces.  False also for arrays or classes with long super chains.
  bool can_be_primary_super() const {
    const juint secondary_offset = in_bytes(secondary_super_cache_offset());
    return super_check_offset() != secondary_offset;
  }
  virtual bool can_be_primary_super_slow() const;

  // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
  juint super_depth() const {
    if (!can_be_primary_super()) {
      return primary_super_limit();
    } else {
      juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
      assert(d < primary_super_limit(), "oob");
      assert(_primary_supers[d] == this, "proper init");
      return d;
    }
  }

  // store an oop into a field of a Klass
  void klass_oop_store(oop* p, oop v);
  void klass_oop_store(volatile oop* p, oop v);

  // java mirror
  oop java_mirror() const              { return _java_mirror; }
  void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }

  // modifier flags
  jint modifier_flags() const          { return _modifier_flags; }
  void set_modifier_flags(jint flags)  { _modifier_flags = flags; }

  // size helper
  int layout_helper() const            { return _layout_helper; }
  void set_layout_helper(int lh)       { _layout_helper = lh; }

  // Note: for instances layout_helper() may include padding.
  // Use InstanceKlass::contains_field_offset to classify field offsets.

  // sub/superklass links
  InstanceKlass* superklass() const;
  Klass* subklass() const;
  Klass* next_sibling() const;
  void append_to_sibling_list();           // add newly created receiver to superklass' subklass list

  void set_next_link(Klass* k) { _next_link = k; }
  Klass* next_link() const { return _next_link; }   // The next klass defined by the class loader.

  // class loader data
  ClassLoaderData* class_loader_data() const               { return _class_loader_data; }
  void set_class_loader_data(ClassLoaderData* loader_data) {  _class_loader_data = loader_data; }

  // The Klasses are not placed in the Heap, so the Card Table or
  // the Mod Union Table can't be used to mark when klasses have modified oops.
  // The CT and MUT bits saves this information for the individual Klasses.
  void record_modified_oops()            { _modified_oops = 1; }
  void clear_modified_oops()             { _modified_oops = 0; }
  bool has_modified_oops()               { return _modified_oops == 1; }

  void accumulate_modified_oops()        { if (has_modified_oops()) _accumulated_modified_oops = 1; }
  void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
  bool has_accumulated_modified_oops()   { return _accumulated_modified_oops == 1; }

 protected:                                // internal accessors
  Klass* subklass_oop() const            { return _subklass; }
  Klass* next_sibling_oop() const        { return _next_sibling; }
  void     set_subklass(Klass* s);
  void     set_next_sibling(Klass* s);

 public:

  // Compiler support
  static ByteSize super_offset()                 { return in_ByteSize(offset_of(Klass, _super)); }
  static ByteSize super_check_offset_offset()    { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
  static ByteSize primary_supers_offset()        { return in_ByteSize(offset_of(Klass, _primary_supers)); }
  static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
  static ByteSize secondary_supers_offset()      { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
  static ByteSize java_mirror_offset()           { return in_ByteSize(offset_of(Klass, _java_mirror)); }
  static ByteSize modifier_flags_offset()        { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
  static ByteSize layout_helper_offset()         { return in_ByteSize(offset_of(Klass, _layout_helper)); }
  static ByteSize access_flags_offset()          { return in_ByteSize(offset_of(Klass, _access_flags)); }

  // Unpacking layout_helper:
  enum {
    _lh_neutral_value           = 0,  // neutral non-array non-instance value
    _lh_instance_slow_path_bit  = 0x01,
    _lh_log2_element_size_shift = BitsPerByte*0,
    _lh_log2_element_size_mask  = BitsPerLong-1,
    _lh_element_type_shift      = BitsPerByte*1,
    _lh_element_type_mask       = right_n_bits(BitsPerByte),  // shifted mask
    _lh_header_size_shift       = BitsPerByte*2,
    _lh_header_size_mask        = right_n_bits(BitsPerByte),  // shifted mask
    _lh_array_tag_bits          = 2,
    _lh_array_tag_shift         = BitsPerInt - _lh_array_tag_bits,
    _lh_array_tag_type_value    = ~0x00,  // 0xC0000000 >> 30
    _lh_array_tag_obj_value     = ~0x01   // 0x80000000 >> 30
  };

  static int layout_helper_size_in_bytes(jint lh) {
    assert(lh > (jint)_lh_neutral_value, "must be instance");
    return (int) lh & ~_lh_instance_slow_path_bit;
  }
  static bool layout_helper_needs_slow_path(jint lh) {
    assert(lh > (jint)_lh_neutral_value, "must be instance");
    return (lh & _lh_instance_slow_path_bit) != 0;
  }
  static bool layout_helper_is_instance(jint lh) {
    return (jint)lh > (jint)_lh_neutral_value;
  }
  static bool layout_helper_is_array(jint lh) {
    return (jint)lh < (jint)_lh_neutral_value;
  }
  static bool layout_helper_is_typeArray(jint lh) {
    // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
    return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
  }
  static bool layout_helper_is_objArray(jint lh) {
    // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
    return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
  }
  static int layout_helper_header_size(jint lh) {
    assert(lh < (jint)_lh_neutral_value, "must be array");
    int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
    assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
    return hsize;
  }
  static BasicType layout_helper_element_type(jint lh) {
    assert(lh < (jint)_lh_neutral_value, "must be array");
    int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
    assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
    return (BasicType) btvalue;
  }
  static int layout_helper_log2_element_size(jint lh) {
    assert(lh < (jint)_lh_neutral_value, "must be array");
    int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
    assert(l2esz <= LogBitsPerLong,
        err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh));
    return l2esz;
  }
  static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
    return (tag        << _lh_array_tag_shift)
      |    (hsize      << _lh_header_size_shift)
      |    ((int)etype << _lh_element_type_shift)
      |    (log2_esize << _lh_log2_element_size_shift);
  }
  static jint instance_layout_helper(jint size, bool slow_path_flag) {
    return (size << LogHeapWordSize)
      |    (slow_path_flag ? _lh_instance_slow_path_bit : 0);
  }
  static int layout_helper_to_size_helper(jint lh) {
    assert(lh > (jint)_lh_neutral_value, "must be instance");
    // Note that the following expression discards _lh_instance_slow_path_bit.
    return lh >> LogHeapWordSize;
  }
  // Out-of-line version computes everything based on the etype:
  static jint array_layout_helper(BasicType etype);

  // What is the maximum number of primary superclasses any klass can have?
#ifdef PRODUCT
  static juint primary_super_limit()         { return _primary_super_limit; }
#else
  static juint primary_super_limit() {
    assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
    return FastSuperclassLimit;
  }
#endif

  // vtables
  virtual klassVtable* vtable() const        { return NULL; }
  virtual int vtable_length() const          { return 0; }

  // subclass check
  bool is_subclass_of(const Klass* k) const;
  // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
  bool is_subtype_of(Klass* k) const {
    juint    off = k->super_check_offset();
    Klass* sup = *(Klass**)( (address)this + off );
    const juint secondary_offset = in_bytes(secondary_super_cache_offset());
    if (sup == k) {
      return true;
    } else if (off != secondary_offset) {
      return false;
    } else {
      return search_secondary_supers(k);
    }
  }
  bool search_secondary_supers(Klass* k) const;

  // Find LCA in class hierarchy
  Klass *LCA( Klass *k );

  // Check whether reflection/jni/jvm code is allowed to instantiate this class;
  // if not, throw either an Error or an Exception.
  virtual void check_valid_for_instantiation(bool throwError, TRAPS);

  // array copying
  virtual void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);

  // tells if the class should be initialized
  virtual bool should_be_initialized() const    { return false; }
  // initializes the klass
  virtual void initialize(TRAPS);
  // lookup operation for MethodLookupCache
  friend class MethodLookupCache;
  virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature) const;
 public:
  Method* lookup_method(Symbol* name, Symbol* signature) const {
    return uncached_lookup_method(name, signature);
  }

  // array class with specific rank
  Klass* array_klass(int rank, TRAPS)         {  return array_klass_impl(false, rank, THREAD); }

  // array class with this klass as element type
  Klass* array_klass(TRAPS)                   {  return array_klass_impl(false, THREAD); }

  // These will return NULL instead of allocating on the heap:
  // NB: these can block for a mutex, like other functions with TRAPS arg.
  Klass* array_klass_or_null(int rank);
  Klass* array_klass_or_null();

  virtual oop protection_domain() const = 0;

  oop class_loader() const;

  virtual oop klass_holder() const      { return class_loader(); }

 protected:
  virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
  virtual Klass* array_klass_impl(bool or_null, TRAPS);

 public:
  // CDS support - remove and restore oops from metadata. Oops are not shared.
  virtual void remove_unshareable_info();
  virtual void restore_unshareable_info(TRAPS);

 protected:
  // computes the subtype relationship
  virtual bool compute_is_subtype_of(Klass* k);
 public:
  // subclass accessor (here for convenience; undefined for non-klass objects)
  virtual bool is_leaf_class() const { fatal("not a class"); return false; }
 public:
  // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
  // These functions describe behavior for the oop not the KLASS.

  // actual oop size of obj in memory
  virtual int oop_size(oop obj) const = 0;

  // Size of klass in word size.
  virtual int size() const = 0;
#if INCLUDE_SERVICES
  virtual void collect_statistics(KlassSizeStats *sz) const;
#endif

  // Returns the Java name for a class (Resource allocated)
  // For arrays, this returns the name of the element with a leading '['.
  // For classes, this returns the name with the package separators
  //     turned into '.'s.
  const char* external_name() const;
  // Returns the name for a class (Resource allocated) as the class
  // would appear in a signature.
  // For arrays, this returns the name of the element with a leading '['.
  // For classes, this returns the name with a leading 'L' and a trailing ';'
  //     and the package separators as '/'.
  virtual const char* signature_name() const;

  // garbage collection support
  virtual void oop_follow_contents(oop obj) = 0;
  virtual int  oop_adjust_pointers(oop obj) = 0;

  // Parallel Scavenge and Parallel Old
  PARALLEL_GC_DECLS_PV

  // type testing operations
 protected:
  virtual bool oop_is_instance_slow()       const { return false; }
  virtual bool oop_is_array_slow()          const { return false; }
  virtual bool oop_is_objArray_slow()       const { return false; }
  virtual bool oop_is_typeArray_slow()      const { return false; }
 public:
  virtual bool oop_is_instanceMirror()      const { return false; }
  virtual bool oop_is_instanceRef()         const { return false; }

  // Fast non-virtual versions
  #ifndef ASSERT
  #define assert_same_query(xval, xcheck) xval
  #else
 private:
  static bool assert_same_query(bool xval, bool xslow) {
    assert(xval == xslow, "slow and fast queries agree");
    return xval;
  }
 public:
  #endif
  inline  bool oop_is_instance()            const { return assert_same_query(
                                                    layout_helper_is_instance(layout_helper()),
                                                    oop_is_instance_slow()); }
  inline  bool oop_is_array()               const { return assert_same_query(
                                                    layout_helper_is_array(layout_helper()),
                                                    oop_is_array_slow()); }
  inline  bool oop_is_objArray()            const { return assert_same_query(
                                                    layout_helper_is_objArray(layout_helper()),
                                                    oop_is_objArray_slow()); }
  inline  bool oop_is_typeArray()           const { return assert_same_query(
                                                    layout_helper_is_typeArray(layout_helper()),
                                                    oop_is_typeArray_slow()); }
  #undef assert_same_query

  // Access flags
  AccessFlags access_flags() const         { return _access_flags;  }
  void set_access_flags(AccessFlags flags) { _access_flags = flags; }

  bool is_public() const                { return _access_flags.is_public(); }
  bool is_final() const                 { return _access_flags.is_final(); }
  bool is_interface() const             { return _access_flags.is_interface(); }
  bool is_abstract() const              { return _access_flags.is_abstract(); }
  bool is_super() const                 { return _access_flags.is_super(); }
  bool is_synthetic() const             { return _access_flags.is_synthetic(); }
  void set_is_synthetic()               { _access_flags.set_is_synthetic(); }
  bool has_finalizer() const            { return _access_flags.has_finalizer(); }
  bool has_final_method() const         { return _access_flags.has_final_method(); }
  void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
  void set_has_final_method()           { _access_flags.set_has_final_method(); }
  bool is_cloneable() const             { return _access_flags.is_cloneable(); }
  void set_is_cloneable()               { _access_flags.set_is_cloneable(); }
  bool has_vanilla_constructor() const  { return _access_flags.has_vanilla_constructor(); }
  void set_has_vanilla_constructor()    { _access_flags.set_has_vanilla_constructor(); }
  bool has_miranda_methods () const     { return access_flags().has_miranda_methods(); }
  void set_has_miranda_methods()        { _access_flags.set_has_miranda_methods(); }

  // Biased locking support
  // Note: the prototype header is always set up to be at least the
  // prototype markOop. If biased locking is enabled it may further be
  // biasable and have an epoch.
  markOop prototype_header() const      { return _prototype_header; }
  // NOTE: once instances of this klass are floating around in the
  // system, this header must only be updated at a safepoint.
  // NOTE 2: currently we only ever set the prototype header to the
  // biasable prototype for instanceKlasses. There is no technical
  // reason why it could not be done for arrayKlasses aside from
  // wanting to reduce the initial scope of this optimization. There
  // are potential problems in setting the bias pattern for
  // JVM-internal oops.
  inline void set_prototype_header(markOop header);
  static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }

  int  biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
  // Atomically increments biased_lock_revocation_count and returns updated value
  int atomic_incr_biased_lock_revocation_count();
  void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
  jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
  void  set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }

  TRACE_DEFINE_KLASS_METHODS;

  // garbage collection support
  virtual void oops_do(OopClosure* cl);

  // Iff the class loader (or mirror for anonymous classes) is alive the
  // Klass is considered alive.
  // The is_alive closure passed in depends on the Garbage Collector used.
  bool is_loader_alive(BoolObjectClosure* is_alive);

  static void clean_weak_klass_links(BoolObjectClosure* is_alive);

  // Prefetch within oop iterators.  This is a macro because we
  // can't guarantee that the compiler will inline it.  In 64-bit
  // it generally doesn't.  Signature is
  //
  // static void prefetch_beyond(oop* const start,
  //                             oop* const end,
  //                             const intx foffset,
  //                             const Prefetch::style pstyle);
#define prefetch_beyond(start, end, foffset, pstyle) {   \
    const intx foffset_ = (foffset);                     \
    const Prefetch::style pstyle_ = (pstyle);            \
    assert(foffset_ > 0, "prefetch beyond, not behind"); \
    if (pstyle_ != Prefetch::do_none) {                  \
      oop* ref = (start);                                \
      if (ref < (end)) {                                 \
        switch (pstyle_) {                               \
        case Prefetch::do_read:                          \
          Prefetch::read(*ref, foffset_);                \
          break;                                         \
        case Prefetch::do_write:                         \
          Prefetch::write(*ref, foffset_);               \
          break;                                         \
        default:                                         \
          ShouldNotReachHere();                          \
          break;                                         \
        }                                                \
      }                                                  \
    }                                                    \
  }

  // iterators
  virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0;
  virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) {
    return oop_oop_iterate(obj, blk);
  }

#if INCLUDE_ALL_GCS
  // In case we don't have a specialized backward scanner use forward
  // iteration.
  virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) {
    return oop_oop_iterate_v(obj, blk);
  }
#endif // INCLUDE_ALL_GCS

  // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
  // (I don't see why the _m should be required, but without it the Solaris
  // C++ gives warning messages about overridings of the "oop_oop_iterate"
  // defined above "hiding" this virtual function.  (DLD, 6/20/00)) */
  virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0;
  virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
    return oop_oop_iterate_m(obj, blk, mr);
  }

  // Versions of the above iterators specialized to particular subtypes
  // of OopClosure, to avoid closure virtual calls.
#define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                \
  virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) {     \
    /* Default implementation reverts to general version. */                 \
    return oop_oop_iterate(obj, blk);                                        \
  }                                                                          \
                                                                             \
  /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
     (I don't see why the _m should be required, but without it the Solaris  \
     C++ gives warning messages about overridings of the "oop_oop_iterate"   \
     defined above "hiding" this virtual function.  (DLD, 6/20/00)) */       \
  virtual int oop_oop_iterate##nv_suffix##_m(oop obj,                        \
                                             OopClosureType* blk,            \
                                             MemRegion mr) {                 \
    return oop_oop_iterate_m(obj, blk, mr);                                  \
  }

  SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
  SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)

#if INCLUDE_ALL_GCS
#define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)      \
  virtual int oop_oop_iterate_backwards##nv_suffix(oop obj,                  \
                                                   OopClosureType* blk) {    \
    /* Default implementation reverts to general version. */                 \
    return oop_oop_iterate_backwards_v(obj, blk);                            \
  }

  SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
  SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
#endif // INCLUDE_ALL_GCS

  virtual void array_klasses_do(void f(Klass* k)) {}

  // Return self, except for abstract classes with exactly 1
  // implementor.  Then return the 1 concrete implementation.
  Klass *up_cast_abstract();

  // klass name
  Symbol* name() const                   { return _name; }
  void set_name(Symbol* n);

 public:
  // jvm support
  virtual jint compute_modifier_flags(TRAPS) const;

  // JVMTI support
  virtual jint jvmti_class_status() const;

  // Printing
  virtual void print_on(outputStream* st) const;

  virtual void oop_print_value_on(oop obj, outputStream* st);
  virtual void oop_print_on      (oop obj, outputStream* st);

  virtual const char* internal_name() const = 0;

  // Verification
  virtual void verify_on(outputStream* st, bool check_dictionary);
  void verify(bool check_dictionary = true) { verify_on(tty, check_dictionary); }

#ifndef PRODUCT
  bool verify_vtable_index(int index);
  bool verify_itable_index(int index);
#endif

  virtual void oop_verify_on(oop obj, outputStream* st);

  static bool is_null(narrowKlass obj);
  static bool is_null(Klass* obj);

  // klass encoding for klass pointer in objects.
  static narrowKlass encode_klass_not_null(Klass* v);
  static narrowKlass encode_klass(Klass* v);

  static Klass* decode_klass_not_null(narrowKlass v);
  static Klass* decode_klass(narrowKlass v);

 private:
  // barriers used by klass_oop_store
  void klass_update_barrier_set(oop v);
  void klass_update_barrier_set_pre(void* p, oop v);
};

#endif // SHARE_VM_OOPS_KLASS_HPP

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