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
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  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   enum PrivateLookupMode  { find_private,  skip_private };
 165 
 166   bool is_klass() const volatile { return true; }
 167 
 168   // super
 169   Klass* super() const               { return _super; }
 170   void set_super(Klass* k)           { _super = k; }
 171 
 172   // initializes _super link, _primary_supers & _secondary_supers arrays
 173   void initialize_supers(Klass* k, TRAPS);
 174   void initialize_supers_impl1(Klass* k);
 175   void initialize_supers_impl2(Klass* k);
 176 
 177   // klass-specific helper for initializing _secondary_supers
 178   virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
 179 
 180   // java_super is the Java-level super type as specified by Class.getSuperClass.
 181   virtual Klass* java_super() const  { return NULL; }
 182 
 183   juint    super_check_offset() const  { return _super_check_offset; }
 184   void set_super_check_offset(juint o) { _super_check_offset = o; }
 185 
 186   Klass* secondary_super_cache() const     { return _secondary_super_cache; }
 187   void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
 188 
 189   Array<Klass*>* secondary_supers() const { return _secondary_supers; }
 190   void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
 191 
 192   // Return the element of the _super chain of the given depth.
 193   // If there is no such element, return either NULL or this.
 194   Klass* primary_super_of_depth(juint i) const {
 195     assert(i < primary_super_limit(), "oob");
 196     Klass* super = _primary_supers[i];
 197     assert(super == NULL || super->super_depth() == i, "correct display");
 198     return super;
 199   }
 200 
 201   // Can this klass be a primary super?  False for interfaces and arrays of
 202   // interfaces.  False also for arrays or classes with long super chains.
 203   bool can_be_primary_super() const {
 204     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 205     return super_check_offset() != secondary_offset;
 206   }
 207   virtual bool can_be_primary_super_slow() const;
 208 
 209   // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
 210   juint super_depth() const {
 211     if (!can_be_primary_super()) {
 212       return primary_super_limit();
 213     } else {
 214       juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
 215       assert(d < primary_super_limit(), "oob");
 216       assert(_primary_supers[d] == this, "proper init");
 217       return d;
 218     }
 219   }
 220 
 221   // store an oop into a field of a Klass
 222   void klass_oop_store(oop* p, oop v);
 223   void klass_oop_store(volatile oop* p, oop v);
 224 
 225   // java mirror
 226   oop java_mirror() const              { return _java_mirror; }
 227   void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
 228 
 229   // modifier flags
 230   jint modifier_flags() const          { return _modifier_flags; }
 231   void set_modifier_flags(jint flags)  { _modifier_flags = flags; }
 232 
 233   // size helper
 234   int layout_helper() const            { return _layout_helper; }
 235   void set_layout_helper(int lh)       { _layout_helper = lh; }
 236 
 237   // Note: for instances layout_helper() may include padding.
 238   // Use InstanceKlass::contains_field_offset to classify field offsets.
 239 
 240   // sub/superklass links
 241   Klass* subklass() const              { return _subklass; }
 242   Klass* next_sibling() const          { return _next_sibling; }
 243   InstanceKlass* superklass() const;
 244   void append_to_sibling_list();           // add newly created receiver to superklass' subklass list
 245 
 246   void set_next_link(Klass* k) { _next_link = k; }
 247   Klass* next_link() const { return _next_link; }   // The next klass defined by the class loader.
 248 
 249   // class loader data
 250   ClassLoaderData* class_loader_data() const               { return _class_loader_data; }
 251   void set_class_loader_data(ClassLoaderData* loader_data) {  _class_loader_data = loader_data; }
 252 
 253   // The Klasses are not placed in the Heap, so the Card Table or
 254   // the Mod Union Table can't be used to mark when klasses have modified oops.
 255   // The CT and MUT bits saves this information for the individual Klasses.
 256   void record_modified_oops()            { _modified_oops = 1; }
 257   void clear_modified_oops()             { _modified_oops = 0; }
 258   bool has_modified_oops()               { return _modified_oops == 1; }
 259 
 260   void accumulate_modified_oops()        { if (has_modified_oops()) _accumulated_modified_oops = 1; }
 261   void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
 262   bool has_accumulated_modified_oops()   { return _accumulated_modified_oops == 1; }
 263 
 264   int shared_classpath_index() const   {
 265     return _shared_class_path_index;
 266   };
 267 
 268   void set_shared_classpath_index(int index) {
 269     _shared_class_path_index = index;
 270   };
 271 
 272 
 273  protected:                                // internal accessors
 274   void     set_subklass(Klass* s);
 275   void     set_next_sibling(Klass* s);
 276 
 277  public:
 278 
 279   // Compiler support
 280   static ByteSize super_offset()                 { return in_ByteSize(offset_of(Klass, _super)); }
 281   static ByteSize super_check_offset_offset()    { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
 282   static ByteSize primary_supers_offset()        { return in_ByteSize(offset_of(Klass, _primary_supers)); }
 283   static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
 284   static ByteSize secondary_supers_offset()      { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
 285   static ByteSize java_mirror_offset()           { return in_ByteSize(offset_of(Klass, _java_mirror)); }
 286   static ByteSize modifier_flags_offset()        { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
 287   static ByteSize layout_helper_offset()         { return in_ByteSize(offset_of(Klass, _layout_helper)); }
 288   static ByteSize access_flags_offset()          { return in_ByteSize(offset_of(Klass, _access_flags)); }
 289 
 290   // Unpacking layout_helper:
 291   enum {
 292     _lh_neutral_value           = 0,  // neutral non-array non-instance value
 293     _lh_instance_slow_path_bit  = 0x01,
 294     _lh_log2_element_size_shift = BitsPerByte*0,
 295     _lh_log2_element_size_mask  = BitsPerLong-1,
 296     _lh_element_type_shift      = BitsPerByte*1,
 297     _lh_element_type_mask       = right_n_bits(BitsPerByte),  // shifted mask
 298     _lh_header_size_shift       = BitsPerByte*2,
 299     _lh_header_size_mask        = right_n_bits(BitsPerByte),  // shifted mask
 300     _lh_array_tag_bits          = 2,
 301     _lh_array_tag_shift         = BitsPerInt - _lh_array_tag_bits,
 302     _lh_array_tag_type_value    = ~0x00,  // 0xC0000000 >> 30
 303     _lh_array_tag_obj_value     = ~0x01   // 0x80000000 >> 30
 304   };
 305 
 306   static int layout_helper_size_in_bytes(jint lh) {
 307     assert(lh > (jint)_lh_neutral_value, "must be instance");
 308     return (int) lh & ~_lh_instance_slow_path_bit;
 309   }
 310   static bool layout_helper_needs_slow_path(jint lh) {
 311     assert(lh > (jint)_lh_neutral_value, "must be instance");
 312     return (lh & _lh_instance_slow_path_bit) != 0;
 313   }
 314   static bool layout_helper_is_instance(jint lh) {
 315     return (jint)lh > (jint)_lh_neutral_value;
 316   }
 317   static bool layout_helper_is_array(jint lh) {
 318     return (jint)lh < (jint)_lh_neutral_value;
 319   }
 320   static bool layout_helper_is_typeArray(jint lh) {
 321     // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
 322     return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
 323   }
 324   static bool layout_helper_is_objArray(jint lh) {
 325     // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
 326     return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
 327   }
 328   static int layout_helper_header_size(jint lh) {
 329     assert(lh < (jint)_lh_neutral_value, "must be array");
 330     int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
 331     assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
 332     return hsize;
 333   }
 334   static BasicType layout_helper_element_type(jint lh) {
 335     assert(lh < (jint)_lh_neutral_value, "must be array");
 336     int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
 337     assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
 338     return (BasicType) btvalue;
 339   }
 340   static int layout_helper_log2_element_size(jint lh) {
 341     assert(lh < (jint)_lh_neutral_value, "must be array");
 342     int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
 343     assert(l2esz <= LogBitsPerLong,
 344         err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh));
 345     return l2esz;
 346   }
 347   static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
 348     return (tag        << _lh_array_tag_shift)
 349       |    (hsize      << _lh_header_size_shift)
 350       |    ((int)etype << _lh_element_type_shift)
 351       |    (log2_esize << _lh_log2_element_size_shift);
 352   }
 353   static jint instance_layout_helper(jint size, bool slow_path_flag) {
 354     return (size << LogHeapWordSize)
 355       |    (slow_path_flag ? _lh_instance_slow_path_bit : 0);
 356   }
 357   static int layout_helper_to_size_helper(jint lh) {
 358     assert(lh > (jint)_lh_neutral_value, "must be instance");
 359     // Note that the following expression discards _lh_instance_slow_path_bit.
 360     return lh >> LogHeapWordSize;
 361   }
 362   // Out-of-line version computes everything based on the etype:
 363   static jint array_layout_helper(BasicType etype);
 364 
 365   // What is the maximum number of primary superclasses any klass can have?
 366 #ifdef PRODUCT
 367   static juint primary_super_limit()         { return _primary_super_limit; }
 368 #else
 369   static juint primary_super_limit() {
 370     assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
 371     return FastSuperclassLimit;
 372   }
 373 #endif
 374 
 375   // vtables
 376   virtual klassVtable* vtable() const        { return NULL; }
 377   virtual int vtable_length() const          { return 0; }
 378 
 379   // subclass check
 380   bool is_subclass_of(const Klass* k) const;
 381   // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
 382   bool is_subtype_of(Klass* k) const {
 383     juint    off = k->super_check_offset();
 384     Klass* sup = *(Klass**)( (address)this + off );
 385     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 386     if (sup == k) {
 387       return true;
 388     } else if (off != secondary_offset) {
 389       return false;
 390     } else {
 391       return search_secondary_supers(k);
 392     }
 393   }
 394   bool search_secondary_supers(Klass* k) const;
 395 
 396   // Find LCA in class hierarchy
 397   Klass *LCA( Klass *k );
 398 
 399   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
 400   // if not, throw either an Error or an Exception.
 401   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
 402 
 403   // array copying
 404   virtual void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
 405 
 406   // tells if the class should be initialized
 407   virtual bool should_be_initialized() const    { return false; }
 408   // initializes the klass
 409   virtual void initialize(TRAPS);
 410   // lookup operation for MethodLookupCache
 411   friend class MethodLookupCache;
 412   virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
 413   virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature, OverpassLookupMode overpass_mode) const;
 414  public:
 415   Method* lookup_method(Symbol* name, Symbol* signature) const {
 416     return uncached_lookup_method(name, signature, find_overpass);
 417   }
 418 
 419   // array class with specific rank
 420   Klass* array_klass(int rank, TRAPS)         {  return array_klass_impl(false, rank, THREAD); }
 421 
 422   // array class with this klass as element type
 423   Klass* array_klass(TRAPS)                   {  return array_klass_impl(false, THREAD); }
 424 
 425   // These will return NULL instead of allocating on the heap:
 426   // NB: these can block for a mutex, like other functions with TRAPS arg.
 427   Klass* array_klass_or_null(int rank);
 428   Klass* array_klass_or_null();
 429 
 430   virtual oop protection_domain() const = 0;
 431 
 432   oop class_loader() const;
 433 
 434   virtual oop klass_holder() const      { return class_loader(); }
 435 
 436  protected:
 437   virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
 438   virtual Klass* array_klass_impl(bool or_null, TRAPS);
 439 
 440  public:
 441   // CDS support - remove and restore oops from metadata. Oops are not shared.
 442   virtual void remove_unshareable_info();
 443   virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
 444 
 445  protected:
 446   // computes the subtype relationship
 447   virtual bool compute_is_subtype_of(Klass* k);
 448  public:
 449   // subclass accessor (here for convenience; undefined for non-klass objects)
 450   virtual bool is_leaf_class() const { fatal("not a class"); return false; }
 451  public:
 452   // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
 453   // These functions describe behavior for the oop not the KLASS.
 454 
 455   // actual oop size of obj in memory
 456   virtual int oop_size(oop obj) const = 0;
 457 
 458   // Size of klass in word size.
 459   virtual int size() const = 0;
 460 #if INCLUDE_SERVICES
 461   virtual void collect_statistics(KlassSizeStats *sz) const;
 462 #endif
 463 
 464   // Returns the Java name for a class (Resource allocated)
 465   // For arrays, this returns the name of the element with a leading '['.
 466   // For classes, this returns the name with the package separators
 467   //     turned into '.'s.
 468   const char* external_name() const;
 469   // Returns the name for a class (Resource allocated) as the class
 470   // would appear in a signature.
 471   // For arrays, this returns the name of the element with a leading '['.
 472   // For classes, this returns the name with a leading 'L' and a trailing ';'
 473   //     and the package separators as '/'.
 474   virtual const char* signature_name() const;
 475 
 476   // type testing operations
 477  protected:
 478   virtual bool oop_is_instance_slow()       const { return false; }
 479   virtual bool oop_is_array_slow()          const { return false; }
 480   virtual bool oop_is_objArray_slow()       const { return false; }
 481   virtual bool oop_is_typeArray_slow()      const { return false; }
 482  public:
 483   virtual bool oop_is_instanceClassLoader() const { return false; }
 484   virtual bool oop_is_instanceMirror()      const { return false; }
 485   virtual bool oop_is_instanceRef()         const { return false; }
 486 
 487   // Fast non-virtual versions
 488   #ifndef ASSERT
 489   #define assert_same_query(xval, xcheck) xval
 490   #else
 491  private:
 492   static bool assert_same_query(bool xval, bool xslow) {
 493     assert(xval == xslow, "slow and fast queries agree");
 494     return xval;
 495   }
 496  public:
 497   #endif
 498   inline  bool oop_is_instance()            const { return assert_same_query(
 499                                                     layout_helper_is_instance(layout_helper()),
 500                                                     oop_is_instance_slow()); }
 501   inline  bool oop_is_array()               const { return assert_same_query(
 502                                                     layout_helper_is_array(layout_helper()),
 503                                                     oop_is_array_slow()); }
 504   inline  bool oop_is_objArray()            const { return assert_same_query(
 505                                                     layout_helper_is_objArray(layout_helper()),
 506                                                     oop_is_objArray_slow()); }
 507   inline  bool oop_is_typeArray()           const { return assert_same_query(
 508                                                     layout_helper_is_typeArray(layout_helper()),
 509                                                     oop_is_typeArray_slow()); }
 510   #undef assert_same_query
 511 
 512   // Access flags
 513   AccessFlags access_flags() const         { return _access_flags;  }
 514   void set_access_flags(AccessFlags flags) { _access_flags = flags; }
 515 
 516   bool is_public() const                { return _access_flags.is_public(); }
 517   bool is_final() const                 { return _access_flags.is_final(); }
 518   bool is_interface() const             { return _access_flags.is_interface(); }
 519   bool is_abstract() const              { return _access_flags.is_abstract(); }
 520   bool is_super() const                 { return _access_flags.is_super(); }
 521   bool is_synthetic() const             { return _access_flags.is_synthetic(); }
 522   void set_is_synthetic()               { _access_flags.set_is_synthetic(); }
 523   bool has_finalizer() const            { return _access_flags.has_finalizer(); }
 524   bool has_final_method() const         { return _access_flags.has_final_method(); }
 525   void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
 526   void set_has_final_method()           { _access_flags.set_has_final_method(); }
 527   bool is_cloneable() const             { return _access_flags.is_cloneable(); }
 528   void set_is_cloneable()               { _access_flags.set_is_cloneable(); }
 529   bool has_vanilla_constructor() const  { return _access_flags.has_vanilla_constructor(); }
 530   void set_has_vanilla_constructor()    { _access_flags.set_has_vanilla_constructor(); }
 531   bool has_miranda_methods () const     { return access_flags().has_miranda_methods(); }
 532   void set_has_miranda_methods()        { _access_flags.set_has_miranda_methods(); }
 533 
 534   // Biased locking support
 535   // Note: the prototype header is always set up to be at least the
 536   // prototype markOop. If biased locking is enabled it may further be
 537   // biasable and have an epoch.
 538   markOop prototype_header() const      { return _prototype_header; }
 539   // NOTE: once instances of this klass are floating around in the
 540   // system, this header must only be updated at a safepoint.
 541   // NOTE 2: currently we only ever set the prototype header to the
 542   // biasable prototype for instanceKlasses. There is no technical
 543   // reason why it could not be done for arrayKlasses aside from
 544   // wanting to reduce the initial scope of this optimization. There
 545   // are potential problems in setting the bias pattern for
 546   // JVM-internal oops.
 547   inline void set_prototype_header(markOop header);
 548   static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
 549 
 550   int  biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
 551   // Atomically increments biased_lock_revocation_count and returns updated value
 552   int atomic_incr_biased_lock_revocation_count();
 553   void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
 554   jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
 555   void  set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
 556 
 557   TRACE_DEFINE_KLASS_METHODS;
 558 
 559   // garbage collection support
 560   void oops_do(OopClosure* cl);
 561 
 562   // Iff the class loader (or mirror for anonymous classes) is alive the
 563   // Klass is considered alive.
 564   // The is_alive closure passed in depends on the Garbage Collector used.
 565   bool is_loader_alive(BoolObjectClosure* is_alive);
 566 
 567   static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
 568   static void clean_subklass_tree(BoolObjectClosure* is_alive) {
 569     clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
 570   }
 571 
 572   // GC specific object visitors
 573   //
 574   // Mark Sweep
 575   virtual void oop_ms_follow_contents(oop obj) = 0;
 576   virtual int  oop_ms_adjust_pointers(oop obj) = 0;
 577 #if INCLUDE_ALL_GCS
 578   // Parallel Scavenge
 579   virtual void oop_ps_push_contents(  oop obj, PSPromotionManager* pm)   = 0;
 580   // Parallel Compact
 581   virtual void oop_pc_follow_contents(oop obj, ParCompactionManager* cm) = 0;
 582   virtual void oop_pc_update_pointers(oop obj) = 0;
 583 #endif
 584 
 585   // Iterators specialized to particular subtypes
 586   // of ExtendedOopClosure, to avoid closure virtual calls.
 587 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                          \
 588   virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) = 0;                        \
 589   /* Iterates "closure" over all the oops in "obj" (of type "this") within "mr". */                    \
 590   virtual int oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) = 0;
 591 
 592   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
 593   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
 594 
 595 #if INCLUDE_ALL_GCS
 596 #define Klass_OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix)                    \
 597   virtual int oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) = 0;
 598 
 599   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
 600   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
 601 #endif // INCLUDE_ALL_GCS
 602 
 603   virtual void array_klasses_do(void f(Klass* k)) {}
 604 
 605   // Return self, except for abstract classes with exactly 1
 606   // implementor.  Then return the 1 concrete implementation.
 607   Klass *up_cast_abstract();
 608 
 609   // klass name
 610   Symbol* name() const                   { return _name; }
 611   void set_name(Symbol* n);
 612 
 613  public:
 614   // jvm support
 615   virtual jint compute_modifier_flags(TRAPS) const;
 616 
 617   // JVMTI support
 618   virtual jint jvmti_class_status() const;
 619 
 620   // Printing
 621   virtual void print_on(outputStream* st) const;
 622 
 623   virtual void oop_print_value_on(oop obj, outputStream* st);
 624   virtual void oop_print_on      (oop obj, outputStream* st);
 625 
 626   virtual const char* internal_name() const = 0;
 627 
 628   // Verification
 629   virtual void verify_on(outputStream* st);
 630   void verify() { verify_on(tty); }
 631 
 632 #ifndef PRODUCT
 633   bool verify_vtable_index(int index);
 634   bool verify_itable_index(int index);
 635 #endif
 636 
 637   virtual void oop_verify_on(oop obj, outputStream* st);
 638 
 639   static bool is_null(narrowKlass obj);
 640   static bool is_null(Klass* obj);
 641 
 642   // klass encoding for klass pointer in objects.
 643   static narrowKlass encode_klass_not_null(Klass* v);
 644   static narrowKlass encode_klass(Klass* v);
 645 
 646   static Klass* decode_klass_not_null(narrowKlass v);
 647   static Klass* decode_klass(narrowKlass v);
 648 
 649  private:
 650   // barriers used by klass_oop_store
 651   void klass_update_barrier_set(oop v);
 652   void klass_update_barrier_set_pre(oop* p, oop v);
 653 };
 654 
 655 // Helper to convert the oop iterate macro suffixes into bool values that can be used by template functions.
 656 #define nvs_nv_to_bool true
 657 #define nvs_v_to_bool  false
 658 #define nvs_to_bool(nv_suffix) nvs##nv_suffix##_to_bool
 659 
 660 // Oop iteration macros for declarations.
 661 // Used to generate declarations in the *Klass header files.
 662 
 663 #define OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                    \
 664   int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure);                        \
 665   int oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr);
 666 
 667 #if INCLUDE_ALL_GCS
 668 #define OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix)              \
 669   int oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure);
 670 #endif // INCLUDE_ALL_GCS
 671 
 672 
 673 // Oop iteration macros for definitions.
 674 // Used to generate definitions in the *Klass.inline.hpp files.
 675 
 676 #define OOP_OOP_ITERATE_DEFN(KlassType, OopClosureType, nv_suffix)             \
 677 int KlassType::oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) {  \
 678   return oop_oop_iterate<nvs_to_bool(nv_suffix)>(obj, closure);                \
 679 }
 680 
 681 #if INCLUDE_ALL_GCS
 682 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)             \
 683 int KlassType::oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) {  \
 684   return oop_oop_iterate_reverse<nvs_to_bool(nv_suffix)>(obj, closure);                  \
 685 }
 686 #else
 687 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)
 688 #endif
 689 
 690 #define OOP_OOP_ITERATE_DEFN_BOUNDED(KlassType, OopClosureType, nv_suffix)                           \
 691 int KlassType::oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) {  \
 692   return oop_oop_iterate_bounded<nvs_to_bool(nv_suffix)>(obj, closure, mr);                          \
 693 }
 694 
 695 #endif // SHARE_VM_OOPS_KLASS_HPP