1 /*
   2  * Copyright (c) 1997, 2015, 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_KLASS_HPP
  26 #define SHARE_VM_OOPS_KLASS_HPP
  27 
  28 #include "gc/shared/specialized_oop_closures.hpp"
  29 #include "memory/iterator.hpp"
  30 #include "memory/memRegion.hpp"
  31 #include "oops/metadata.hpp"
  32 #include "oops/oop.hpp"
  33 #include "trace/traceMacros.hpp"
  34 #include "utilities/accessFlags.hpp"
  35 #include "utilities/macros.hpp"
  36 
  37 //
  38 // A Klass provides:
  39 //  1: language level class object (method dictionary etc.)
  40 //  2: provide vm dispatch behavior for the object
  41 // Both functions are combined into one C++ class.
  42 
  43 // One reason for the oop/klass dichotomy in the implementation is
  44 // that we don't want a C++ vtbl pointer in every object.  Thus,
  45 // normal oops don't have any virtual functions.  Instead, they
  46 // forward all "virtual" functions to their klass, which does have
  47 // a vtbl and does the C++ dispatch depending on the object's
  48 // actual type.  (See oop.inline.hpp for some of the forwarding code.)
  49 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
  50 
  51 // Forward declarations.
  52 template <class T> class Array;
  53 template <class T> class GrowableArray;
  54 class ClassLoaderData;
  55 class klassVtable;
  56 class ParCompactionManager;
  57 class PSPromotionManager;
  58 class KlassSizeStats;
  59 class fieldDescriptor;
  60 
  61 class Klass : public Metadata {
  62   friend class VMStructs;
  63  protected:
  64   // note: put frequently-used fields together at start of klass structure
  65   // for better cache behavior (may not make much of a difference but sure won't hurt)
  66   enum { _primary_super_limit = 8 };
  67 
  68   // The "layout helper" is a combined descriptor of object layout.
  69   // For klasses which are neither instance nor array, the value is zero.
  70   //
  71   // For instances, layout helper is a positive number, the instance size.
  72   // This size is already passed through align_object_size and scaled to bytes.
  73   // The low order bit is set if instances of this class cannot be
  74   // allocated using the fastpath.
  75   //
  76   // For arrays, layout helper is a negative number, containing four
  77   // distinct bytes, as follows:
  78   //    MSB:[tag, hsz, ebt, log2(esz)]:LSB
  79   // where:
  80   //    tag is 0x80 if the elements are oops, 0xC0 if non-oops
  81   //    hsz is array header size in bytes (i.e., offset of first element)
  82   //    ebt is the BasicType of the elements
  83   //    esz is the element size in bytes
  84   // This packed word is arranged so as to be quickly unpacked by the
  85   // various fast paths that use the various subfields.
  86   //
  87   // The esz bits can be used directly by a SLL instruction, without masking.
  88   //
  89   // Note that the array-kind tag looks like 0x00 for instance klasses,
  90   // since their length in bytes is always less than 24Mb.
  91   //
  92   // Final note:  This comes first, immediately after C++ vtable,
  93   // because it is frequently queried.
  94   jint        _layout_helper;
  95 
  96   // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
  97   // and _primary_supers all help make fast subtype checks.  See big discussion
  98   // in doc/server_compiler/checktype.txt
  99   //
 100   // Where to look to observe a supertype (it is &_secondary_super_cache for
 101   // secondary supers, else is &_primary_supers[depth()].
 102   juint       _super_check_offset;
 103 
 104   // Class name.  Instance classes: java/lang/String, etc.  Array classes: [I,
 105   // [Ljava/lang/String;, etc.  Set to zero for all other kinds of classes.
 106   Symbol*     _name;
 107 
 108   // Cache of last observed secondary supertype
 109   Klass*      _secondary_super_cache;
 110   // Array of all secondary supertypes
 111   Array<Klass*>* _secondary_supers;
 112   // Ordered list of all primary supertypes
 113   Klass*      _primary_supers[_primary_super_limit];
 114   // java/lang/Class instance mirroring this class
 115   oop       _java_mirror;
 116   // Superclass
 117   Klass*      _super;
 118   // First subclass (NULL if none); _subklass->next_sibling() is next one
 119   Klass*      _subklass;
 120   // Sibling link (or NULL); links all subklasses of a klass
 121   Klass*      _next_sibling;
 122 
 123   // All klasses loaded by a class loader are chained through these links
 124   Klass*      _next_link;
 125 
 126   // The VM's representation of the ClassLoader used to load this class.
 127   // Provide access the corresponding instance java.lang.ClassLoader.
 128   ClassLoaderData* _class_loader_data;
 129 
 130   jint        _modifier_flags;  // Processed access flags, for use by Class.getModifiers.
 131   AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.
 132 
 133   // Biased locking implementation and statistics
 134   // (the 64-bit chunk goes first, to avoid some fragmentation)
 135   jlong    _last_biased_lock_bulk_revocation_time;
 136   markOop  _prototype_header;   // Used when biased locking is both enabled and disabled for this type
 137   jint     _biased_lock_revocation_count;
 138 
 139   TRACE_DEFINE_KLASS_TRACE_ID;
 140 
 141   // Remembered sets support for the oops in the klasses.
 142   jbyte _modified_oops;             // Card Table Equivalent (YC/CMS support)
 143   jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
 144 
 145 private:
 146   // This is an index into FileMapHeader::_classpath_entry_table[], to
 147   // associate this class with the JAR file where it's loaded from during
 148   // dump time. If a class is not loaded from the shared archive, this field is
 149   // -1.
 150   jshort _shared_class_path_index;
 151 
 152   friend class SharedClassUtil;
 153 protected:
 154 
 155   // Constructor
 156   Klass();
 157 
 158   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
 159 
 160  public:
 161   enum DefaultsLookupMode { find_defaults, skip_defaults };
 162   enum OverpassLookupMode { find_overpass, skip_overpass };
 163   enum StaticLookupMode   { find_static,   skip_static };
 164 
 165   bool is_klass() const volatile { return true; }
 166 
 167   // super
 168   Klass* super() const               { return _super; }
 169   void set_super(Klass* k)           { _super = k; }
 170 
 171   // initializes _super link, _primary_supers & _secondary_supers arrays
 172   void initialize_supers(Klass* k, TRAPS);
 173   void initialize_supers_impl1(Klass* k);
 174   void initialize_supers_impl2(Klass* k);
 175 
 176   // klass-specific helper for initializing _secondary_supers
 177   virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
 178 
 179   // java_super is the Java-level super type as specified by Class.getSuperClass.
 180   virtual Klass* java_super() const  { return NULL; }
 181 
 182   juint    super_check_offset() const  { return _super_check_offset; }
 183   void set_super_check_offset(juint o) { _super_check_offset = o; }
 184 
 185   Klass* secondary_super_cache() const     { return _secondary_super_cache; }
 186   void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
 187 
 188   Array<Klass*>* secondary_supers() const { return _secondary_supers; }
 189   void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
 190 
 191   // Return the element of the _super chain of the given depth.
 192   // If there is no such element, return either NULL or this.
 193   Klass* primary_super_of_depth(juint i) const {
 194     assert(i < primary_super_limit(), "oob");
 195     Klass* super = _primary_supers[i];
 196     assert(super == NULL || super->super_depth() == i, "correct display");
 197     return super;
 198   }
 199 
 200   // Can this klass be a primary super?  False for interfaces and arrays of
 201   // interfaces.  False also for arrays or classes with long super chains.
 202   bool can_be_primary_super() const {
 203     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 204     return super_check_offset() != secondary_offset;
 205   }
 206   virtual bool can_be_primary_super_slow() const;
 207 
 208   // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
 209   juint super_depth() const {
 210     if (!can_be_primary_super()) {
 211       return primary_super_limit();
 212     } else {
 213       juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
 214       assert(d < primary_super_limit(), "oob");
 215       assert(_primary_supers[d] == this, "proper init");
 216       return d;
 217     }
 218   }
 219 
 220   // store an oop into a field of a Klass
 221   void klass_oop_store(oop* p, oop v);
 222   void klass_oop_store(volatile oop* p, oop v);
 223 
 224   // java mirror
 225   oop java_mirror() const              { return _java_mirror; }
 226   void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
 227 
 228   // modifier flags
 229   jint modifier_flags() const          { return _modifier_flags; }
 230   void set_modifier_flags(jint flags)  { _modifier_flags = flags; }
 231 
 232   // size helper
 233   int layout_helper() const            { return _layout_helper; }
 234   void set_layout_helper(int lh)       { _layout_helper = lh; }
 235 
 236   // Note: for instances layout_helper() may include padding.
 237   // Use InstanceKlass::contains_field_offset to classify field offsets.
 238 
 239   // sub/superklass links
 240   Klass* subklass() const              { return _subklass; }
 241   Klass* next_sibling() const          { return _next_sibling; }
 242   InstanceKlass* superklass() const;
 243   void append_to_sibling_list();           // add newly created receiver to superklass' subklass list
 244 
 245   void set_next_link(Klass* k) { _next_link = k; }
 246   Klass* next_link() const { return _next_link; }   // The next klass defined by the class loader.
 247 
 248   // class loader data
 249   ClassLoaderData* class_loader_data() const               { return _class_loader_data; }
 250   void set_class_loader_data(ClassLoaderData* loader_data) {  _class_loader_data = loader_data; }
 251 
 252   // The Klasses are not placed in the Heap, so the Card Table or
 253   // the Mod Union Table can't be used to mark when klasses have modified oops.
 254   // The CT and MUT bits saves this information for the individual Klasses.
 255   void record_modified_oops()            { _modified_oops = 1; }
 256   void clear_modified_oops()             { _modified_oops = 0; }
 257   bool has_modified_oops()               { return _modified_oops == 1; }
 258 
 259   void accumulate_modified_oops()        { if (has_modified_oops()) _accumulated_modified_oops = 1; }
 260   void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
 261   bool has_accumulated_modified_oops()   { return _accumulated_modified_oops == 1; }
 262 
 263   int shared_classpath_index() const   {
 264     return _shared_class_path_index;
 265   };
 266 
 267   void set_shared_classpath_index(int index) {
 268     _shared_class_path_index = index;
 269   };
 270 
 271 
 272  protected:                                // internal accessors
 273   void     set_subklass(Klass* s);
 274   void     set_next_sibling(Klass* s);
 275 
 276  public:
 277 
 278   // Compiler support
 279   static ByteSize super_offset()                 { return in_ByteSize(offset_of(Klass, _super)); }
 280   static ByteSize super_check_offset_offset()    { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
 281   static ByteSize primary_supers_offset()        { return in_ByteSize(offset_of(Klass, _primary_supers)); }
 282   static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
 283   static ByteSize secondary_supers_offset()      { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
 284   static ByteSize java_mirror_offset()           { return in_ByteSize(offset_of(Klass, _java_mirror)); }
 285   static ByteSize modifier_flags_offset()        { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
 286   static ByteSize layout_helper_offset()         { return in_ByteSize(offset_of(Klass, _layout_helper)); }
 287   static ByteSize access_flags_offset()          { return in_ByteSize(offset_of(Klass, _access_flags)); }
 288 
 289   // Unpacking layout_helper:
 290   enum {
 291     _lh_neutral_value           = 0,  // neutral non-array non-instance value
 292     _lh_instance_slow_path_bit  = 0x01,
 293     _lh_log2_element_size_shift = BitsPerByte*0,
 294     _lh_log2_element_size_mask  = BitsPerLong-1,
 295     _lh_element_type_shift      = BitsPerByte*1,
 296     _lh_element_type_mask       = right_n_bits(BitsPerByte),  // shifted mask
 297     _lh_header_size_shift       = BitsPerByte*2,
 298     _lh_header_size_mask        = right_n_bits(BitsPerByte),  // shifted mask
 299     _lh_array_tag_bits          = 2,
 300     _lh_array_tag_shift         = BitsPerInt - _lh_array_tag_bits,
 301     _lh_array_tag_type_value    = ~0x00,  // 0xC0000000 >> 30
 302     _lh_array_tag_obj_value     = ~0x01   // 0x80000000 >> 30
 303   };
 304 
 305   static int layout_helper_size_in_bytes(jint lh) {
 306     assert(lh > (jint)_lh_neutral_value, "must be instance");
 307     return (int) lh & ~_lh_instance_slow_path_bit;
 308   }
 309   static bool layout_helper_needs_slow_path(jint lh) {
 310     assert(lh > (jint)_lh_neutral_value, "must be instance");
 311     return (lh & _lh_instance_slow_path_bit) != 0;
 312   }
 313   static bool layout_helper_is_instance(jint lh) {
 314     return (jint)lh > (jint)_lh_neutral_value;
 315   }
 316   static bool layout_helper_is_array(jint lh) {
 317     return (jint)lh < (jint)_lh_neutral_value;
 318   }
 319   static bool layout_helper_is_typeArray(jint lh) {
 320     // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
 321     return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
 322   }
 323   static bool layout_helper_is_objArray(jint lh) {
 324     // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
 325     return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
 326   }
 327   static int layout_helper_header_size(jint lh) {
 328     assert(lh < (jint)_lh_neutral_value, "must be array");
 329     int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
 330     assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
 331     return hsize;
 332   }
 333   static BasicType layout_helper_element_type(jint lh) {
 334     assert(lh < (jint)_lh_neutral_value, "must be array");
 335     int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
 336     assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
 337     return (BasicType) btvalue;
 338   }
 339   static int layout_helper_log2_element_size(jint lh) {
 340     assert(lh < (jint)_lh_neutral_value, "must be array");
 341     int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
 342     assert(l2esz <= LogBitsPerLong,
 343         err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh));
 344     return l2esz;
 345   }
 346   static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
 347     return (tag        << _lh_array_tag_shift)
 348       |    (hsize      << _lh_header_size_shift)
 349       |    ((int)etype << _lh_element_type_shift)
 350       |    (log2_esize << _lh_log2_element_size_shift);
 351   }
 352   static jint instance_layout_helper(jint size, bool slow_path_flag) {
 353     return (size << LogHeapWordSize)
 354       |    (slow_path_flag ? _lh_instance_slow_path_bit : 0);
 355   }
 356   static int layout_helper_to_size_helper(jint lh) {
 357     assert(lh > (jint)_lh_neutral_value, "must be instance");
 358     // Note that the following expression discards _lh_instance_slow_path_bit.
 359     return lh >> LogHeapWordSize;
 360   }
 361   // Out-of-line version computes everything based on the etype:
 362   static jint array_layout_helper(BasicType etype);
 363 
 364   // What is the maximum number of primary superclasses any klass can have?
 365 #ifdef PRODUCT
 366   static juint primary_super_limit()         { return _primary_super_limit; }
 367 #else
 368   static juint primary_super_limit() {
 369     assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
 370     return FastSuperclassLimit;
 371   }
 372 #endif
 373 
 374   // vtables
 375   virtual klassVtable* vtable() const        { return NULL; }
 376   virtual int vtable_length() const          { return 0; }
 377 
 378   // subclass check
 379   bool is_subclass_of(const Klass* k) const;
 380   // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
 381   bool is_subtype_of(Klass* k) const {
 382     juint    off = k->super_check_offset();
 383     Klass* sup = *(Klass**)( (address)this + off );
 384     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 385     if (sup == k) {
 386       return true;
 387     } else if (off != secondary_offset) {
 388       return false;
 389     } else {
 390       return search_secondary_supers(k);
 391     }
 392   }
 393   bool search_secondary_supers(Klass* k) const;
 394 
 395   // Find LCA in class hierarchy
 396   Klass *LCA( Klass *k );
 397 
 398   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
 399   // if not, throw either an Error or an Exception.
 400   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
 401 
 402   // array copying
 403   virtual void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
 404 
 405   // tells if the class should be initialized
 406   virtual bool should_be_initialized() const    { return false; }
 407   // initializes the klass
 408   virtual void initialize(TRAPS);
 409   // lookup operation for MethodLookupCache
 410   friend class MethodLookupCache;
 411   virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
 412   virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature, OverpassLookupMode overpass_mode) const;
 413  public:
 414   Method* lookup_method(Symbol* name, Symbol* signature) const {
 415     return uncached_lookup_method(name, signature, find_overpass);
 416   }
 417 
 418   // array class with specific rank
 419   Klass* array_klass(int rank, TRAPS)         {  return array_klass_impl(false, rank, THREAD); }
 420 
 421   // array class with this klass as element type
 422   Klass* array_klass(TRAPS)                   {  return array_klass_impl(false, THREAD); }
 423 
 424   // These will return NULL instead of allocating on the heap:
 425   // NB: these can block for a mutex, like other functions with TRAPS arg.
 426   Klass* array_klass_or_null(int rank);
 427   Klass* array_klass_or_null();
 428 
 429   virtual oop protection_domain() const = 0;
 430 
 431   oop class_loader() const;
 432 
 433   virtual oop klass_holder() const      { return class_loader(); }
 434 
 435  protected:
 436   virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
 437   virtual Klass* array_klass_impl(bool or_null, TRAPS);
 438 
 439  public:
 440   // CDS support - remove and restore oops from metadata. Oops are not shared.
 441   virtual void remove_unshareable_info();
 442   virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
 443 
 444  protected:
 445   // computes the subtype relationship
 446   virtual bool compute_is_subtype_of(Klass* k);
 447  public:
 448   // subclass accessor (here for convenience; undefined for non-klass objects)
 449   virtual bool is_leaf_class() const { fatal("not a class"); return false; }
 450  public:
 451   // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
 452   // These functions describe behavior for the oop not the KLASS.
 453 
 454   // actual oop size of obj in memory
 455   virtual int oop_size(oop obj) const = 0;
 456 
 457   // Size of klass in word size.
 458   virtual int size() const = 0;
 459 #if INCLUDE_SERVICES
 460   virtual void collect_statistics(KlassSizeStats *sz) const;
 461 #endif
 462 
 463   // Returns the Java name for a class (Resource allocated)
 464   // For arrays, this returns the name of the element with a leading '['.
 465   // For classes, this returns the name with the package separators
 466   //     turned into '.'s.
 467   const char* external_name() const;
 468   // Returns the name for a class (Resource allocated) as the class
 469   // would appear in a signature.
 470   // For arrays, this returns the name of the element with a leading '['.
 471   // For classes, this returns the name with a leading 'L' and a trailing ';'
 472   //     and the package separators as '/'.
 473   virtual const char* signature_name() const;
 474 
 475   // type testing operations
 476  protected:
 477   virtual bool oop_is_instance_slow()       const { return false; }
 478   virtual bool oop_is_array_slow()          const { return false; }
 479   virtual bool oop_is_objArray_slow()       const { return false; }
 480   virtual bool oop_is_typeArray_slow()      const { return false; }
 481  public:
 482   virtual bool oop_is_instanceClassLoader() const { return false; }
 483   virtual bool oop_is_instanceMirror()      const { return false; }
 484   virtual bool oop_is_instanceRef()         const { return false; }
 485 
 486   // Fast non-virtual versions
 487   #ifndef ASSERT
 488   #define assert_same_query(xval, xcheck) xval
 489   #else
 490  private:
 491   static bool assert_same_query(bool xval, bool xslow) {
 492     assert(xval == xslow, "slow and fast queries agree");
 493     return xval;
 494   }
 495  public:
 496   #endif
 497   inline  bool oop_is_instance()            const { return assert_same_query(
 498                                                     layout_helper_is_instance(layout_helper()),
 499                                                     oop_is_instance_slow()); }
 500   inline  bool oop_is_array()               const { return assert_same_query(
 501                                                     layout_helper_is_array(layout_helper()),
 502                                                     oop_is_array_slow()); }
 503   inline  bool oop_is_objArray()            const { return assert_same_query(
 504                                                     layout_helper_is_objArray(layout_helper()),
 505                                                     oop_is_objArray_slow()); }
 506   inline  bool oop_is_typeArray()           const { return assert_same_query(
 507                                                     layout_helper_is_typeArray(layout_helper()),
 508                                                     oop_is_typeArray_slow()); }
 509   #undef assert_same_query
 510 
 511   // Access flags
 512   AccessFlags access_flags() const         { return _access_flags;  }
 513   void set_access_flags(AccessFlags flags) { _access_flags = flags; }
 514 
 515   bool is_public() const                { return _access_flags.is_public(); }
 516   bool is_final() const                 { return _access_flags.is_final(); }
 517   bool is_interface() const             { return _access_flags.is_interface(); }
 518   bool is_abstract() const              { return _access_flags.is_abstract(); }
 519   bool is_super() const                 { return _access_flags.is_super(); }
 520   bool is_synthetic() const             { return _access_flags.is_synthetic(); }
 521   void set_is_synthetic()               { _access_flags.set_is_synthetic(); }
 522   bool has_finalizer() const            { return _access_flags.has_finalizer(); }
 523   bool has_final_method() const         { return _access_flags.has_final_method(); }
 524   void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
 525   void set_has_final_method()           { _access_flags.set_has_final_method(); }
 526   bool is_cloneable() const             { return _access_flags.is_cloneable(); }
 527   void set_is_cloneable()               { _access_flags.set_is_cloneable(); }
 528   bool has_vanilla_constructor() const  { return _access_flags.has_vanilla_constructor(); }
 529   void set_has_vanilla_constructor()    { _access_flags.set_has_vanilla_constructor(); }
 530   bool has_miranda_methods () const     { return access_flags().has_miranda_methods(); }
 531   void set_has_miranda_methods()        { _access_flags.set_has_miranda_methods(); }
 532 
 533   // Biased locking support
 534   // Note: the prototype header is always set up to be at least the
 535   // prototype markOop. If biased locking is enabled it may further be
 536   // biasable and have an epoch.
 537   markOop prototype_header() const      { return _prototype_header; }
 538   // NOTE: once instances of this klass are floating around in the
 539   // system, this header must only be updated at a safepoint.
 540   // NOTE 2: currently we only ever set the prototype header to the
 541   // biasable prototype for instanceKlasses. There is no technical
 542   // reason why it could not be done for arrayKlasses aside from
 543   // wanting to reduce the initial scope of this optimization. There
 544   // are potential problems in setting the bias pattern for
 545   // JVM-internal oops.
 546   inline void set_prototype_header(markOop header);
 547   static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
 548 
 549   int  biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
 550   // Atomically increments biased_lock_revocation_count and returns updated value
 551   int atomic_incr_biased_lock_revocation_count();
 552   void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
 553   jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
 554   void  set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
 555 
 556   TRACE_DEFINE_KLASS_METHODS;
 557 
 558   // garbage collection support
 559   void oops_do(OopClosure* cl);
 560 
 561   // Iff the class loader (or mirror for anonymous classes) is alive the
 562   // Klass is considered alive.
 563   // The is_alive closure passed in depends on the Garbage Collector used.
 564   bool is_loader_alive(BoolObjectClosure* is_alive);
 565 
 566   static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
 567   static void clean_subklass_tree(BoolObjectClosure* is_alive) {
 568     clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
 569   }
 570 
 571   // GC specific object visitors
 572   //
 573   // Mark Sweep
 574   virtual void oop_ms_follow_contents(oop obj) = 0;
 575   virtual int  oop_ms_adjust_pointers(oop obj) = 0;
 576 #if INCLUDE_ALL_GCS
 577   // Parallel Scavenge
 578   virtual void oop_ps_push_contents(  oop obj, PSPromotionManager* pm)   = 0;
 579   // Parallel Compact
 580   virtual void oop_pc_follow_contents(oop obj, ParCompactionManager* cm) = 0;
 581   virtual void oop_pc_update_pointers(oop obj) = 0;
 582 #endif
 583 
 584   // Iterators specialized to particular subtypes
 585   // of ExtendedOopClosure, to avoid closure virtual calls.
 586 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                      \
 587   virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) = 0;                    \
 588   /* Iterates "closure" over all the oops in "obj" (of type "this") within "mr". */                \
 589   virtual int oop_oop_iterate##nv_suffix##_m(oop obj, OopClosureType* closure, MemRegion mr) = 0;
 590 
 591   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
 592   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
 593 
 594 #if INCLUDE_ALL_GCS
 595 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)                    \
 596   virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) = 0;
 597 
 598   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 599   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 600 #endif // INCLUDE_ALL_GCS
 601 
 602   virtual void array_klasses_do(void f(Klass* k)) {}
 603 
 604   // Return self, except for abstract classes with exactly 1
 605   // implementor.  Then return the 1 concrete implementation.
 606   Klass *up_cast_abstract();
 607 
 608   // klass name
 609   Symbol* name() const                   { return _name; }
 610   void set_name(Symbol* n);
 611 
 612  public:
 613   // jvm support
 614   virtual jint compute_modifier_flags(TRAPS) const;
 615 
 616   // JVMTI support
 617   virtual jint jvmti_class_status() const;
 618 
 619   // Printing
 620   virtual void print_on(outputStream* st) const;
 621 
 622   virtual void oop_print_value_on(oop obj, outputStream* st);
 623   virtual void oop_print_on      (oop obj, outputStream* st);
 624 
 625   virtual const char* internal_name() const = 0;
 626 
 627   // Verification
 628   virtual void verify_on(outputStream* st);
 629   void verify() { verify_on(tty); }
 630 
 631 #ifndef PRODUCT
 632   bool verify_vtable_index(int index);
 633   bool verify_itable_index(int index);
 634 #endif
 635 
 636   virtual void oop_verify_on(oop obj, outputStream* st);
 637 
 638   static bool is_null(narrowKlass obj);
 639   static bool is_null(Klass* obj);
 640 
 641   // klass encoding for klass pointer in objects.
 642   static narrowKlass encode_klass_not_null(Klass* v);
 643   static narrowKlass encode_klass(Klass* v);
 644 
 645   static Klass* decode_klass_not_null(narrowKlass v);
 646   static Klass* decode_klass(narrowKlass v);
 647 
 648  private:
 649   // barriers used by klass_oop_store
 650   void klass_update_barrier_set(oop v);
 651   void klass_update_barrier_set_pre(oop* p, oop v);
 652 };
 653 
 654 #endif // SHARE_VM_OOPS_KLASS_HPP