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.
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  23  */
  24 
  25 #ifndef SHARE_VM_OOPS_KLASS_HPP
  26 #define SHARE_VM_OOPS_KLASS_HPP
  27 
  28 #include "memory/genOopClosures.hpp"
  29 #include "memory/iterator.hpp"
  30 #include "memory/memRegion.hpp"
  31 #include "memory/specialized_oop_closures.hpp"
  32 #include "oops/klassPS.hpp"
  33 #include "oops/metadata.hpp"
  34 #include "oops/oop.hpp"
  35 #include "trace/traceMacros.hpp"
  36 #include "utilities/accessFlags.hpp"
  37 #include "utilities/macros.hpp"
  38 #if INCLUDE_ALL_GCS
  39 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp"
  40 #include "gc_implementation/g1/g1OopClosures.hpp"
  41 #include "gc_implementation/parNew/parOopClosures.hpp"
  42 #endif // INCLUDE_ALL_GCS
  43 
  44 //
  45 // A Klass provides:
  46 //  1: language level class object (method dictionary etc.)
  47 //  2: provide vm dispatch behavior for the object
  48 // Both functions are combined into one C++ class.
  49 
  50 // One reason for the oop/klass dichotomy in the implementation is
  51 // that we don't want a C++ vtbl pointer in every object.  Thus,
  52 // normal oops don't have any virtual functions.  Instead, they
  53 // forward all "virtual" functions to their klass, which does have
  54 // a vtbl and does the C++ dispatch depending on the object's
  55 // actual type.  (See oop.inline.hpp for some of the forwarding code.)
  56 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
  57 
  58 // Forward declarations.
  59 template <class T> class Array;
  60 template <class T> class GrowableArray;
  61 class ClassLoaderData;
  62 class klassVtable;
  63 class ParCompactionManager;
  64 class KlassSizeStats;
  65 class fieldDescriptor;
  66 
  67 class Klass : public Metadata {
  68   friend class VMStructs;
  69  protected:
  70   // note: put frequently-used fields together at start of klass structure
  71   // for better cache behavior (may not make much of a difference but sure won't hurt)
  72   enum { _primary_super_limit = 8 };
  73 
  74   // The "layout helper" is a combined descriptor of object layout.
  75   // For klasses which are neither instance nor array, the value is zero.
  76   //
  77   // For instances, layout helper is a positive number, the instance size.
  78   // This size is already passed through align_object_size and scaled to bytes.
  79   // The low order bit is set if instances of this class cannot be
  80   // allocated using the fastpath.
  81   //
  82   // For arrays, layout helper is a negative number, containing four
  83   // distinct bytes, as follows:
  84   //    MSB:[tag, hsz, ebt, log2(esz)]:LSB
  85   // where:
  86   //    tag is 0x80 if the elements are oops, 0xC0 if non-oops
  87   //    hsz is array header size in bytes (i.e., offset of first element)
  88   //    ebt is the BasicType of the elements
  89   //    esz is the element size in bytes
  90   // This packed word is arranged so as to be quickly unpacked by the
  91   // various fast paths that use the various subfields.
  92   //
  93   // The esz bits can be used directly by a SLL instruction, without masking.
  94   //
  95   // Note that the array-kind tag looks like 0x00 for instance klasses,
  96   // since their length in bytes is always less than 24Mb.
  97   //
  98   // Final note:  This comes first, immediately after C++ vtable,
  99   // because it is frequently queried.
 100   jint        _layout_helper;
 101 
 102   // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
 103   // and _primary_supers all help make fast subtype checks.  See big discussion
 104   // in doc/server_compiler/checktype.txt
 105   //
 106   // Where to look to observe a supertype (it is &_secondary_super_cache for
 107   // secondary supers, else is &_primary_supers[depth()].
 108   juint       _super_check_offset;
 109 
 110   // Class name.  Instance classes: java/lang/String, etc.  Array classes: [I,
 111   // [Ljava/lang/String;, etc.  Set to zero for all other kinds of classes.
 112   Symbol*     _name;
 113 
 114   // Cache of last observed secondary supertype
 115   Klass*      _secondary_super_cache;
 116   // Array of all secondary supertypes
 117   Array<Klass*>* _secondary_supers;
 118   // Ordered list of all primary supertypes
 119   Klass*      _primary_supers[_primary_super_limit];
 120   // java/lang/Class instance mirroring this class
 121   oop       _java_mirror;
 122   // Superclass
 123   Klass*      _super;
 124   // First subclass (NULL if none); _subklass->next_sibling() is next one
 125   Klass*      _subklass;
 126   // Sibling link (or NULL); links all subklasses of a klass
 127   Klass*      _next_sibling;
 128 
 129   // All klasses loaded by a class loader are chained through these links
 130   Klass*      _next_link;
 131 
 132   // The VM's representation of the ClassLoader used to load this class.
 133   // Provide access the corresponding instance java.lang.ClassLoader.
 134   ClassLoaderData* _class_loader_data;
 135 
 136   jint        _modifier_flags;  // Processed access flags, for use by Class.getModifiers.
 137   AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.
 138 
 139   // Biased locking implementation and statistics
 140   // (the 64-bit chunk goes first, to avoid some fragmentation)
 141   jlong    _last_biased_lock_bulk_revocation_time;
 142   markOop  _prototype_header;   // Used when biased locking is both enabled and disabled for this type
 143   jint     _biased_lock_revocation_count;
 144 
 145   TRACE_DEFINE_KLASS_TRACE_ID;
 146 
 147   // Remembered sets support for the oops in the klasses.
 148   jbyte _modified_oops;             // Card Table Equivalent (YC/CMS support)
 149   jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
 150 
 151 private:
 152   // This is an index into FileMapHeader::_classpath_entry_table[], to
 153   // associate this class with the JAR file where it's loaded from during
 154   // dump time. If a class is not loaded from the shared archive, this field is
 155   // -1.
 156   jshort _shared_class_path_index;
 157 
 158   friend class SharedClassUtil;
 159 protected:
 160 
 161   // Constructor
 162   Klass();
 163 
 164   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
 165 
 166  public:
 167   enum DefaultsLookupMode { find_defaults, skip_defaults };
 168   enum OverpassLookupMode { find_overpass, skip_overpass };
 169   enum StaticLookupMode   { find_static,   skip_static };
 170 
 171   bool is_klass() const volatile { return true; }
 172 
 173   // super
 174   Klass* super() const               { return _super; }
 175   void set_super(Klass* k)           { _super = k; }
 176 
 177   // initializes _super link, _primary_supers & _secondary_supers arrays
 178   void initialize_supers(Klass* k, TRAPS);
 179   void initialize_supers_impl1(Klass* k);
 180   void initialize_supers_impl2(Klass* k);
 181 
 182   // klass-specific helper for initializing _secondary_supers
 183   virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
 184 
 185   // java_super is the Java-level super type as specified by Class.getSuperClass.
 186   virtual Klass* java_super() const  { return NULL; }
 187 
 188   juint    super_check_offset() const  { return _super_check_offset; }
 189   void set_super_check_offset(juint o) { _super_check_offset = o; }
 190 
 191   Klass* secondary_super_cache() const     { return _secondary_super_cache; }
 192   void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
 193 
 194   Array<Klass*>* secondary_supers() const { return _secondary_supers; }
 195   void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
 196 
 197   // Return the element of the _super chain of the given depth.
 198   // If there is no such element, return either NULL or this.
 199   Klass* primary_super_of_depth(juint i) const {
 200     assert(i < primary_super_limit(), "oob");
 201     Klass* super = _primary_supers[i];
 202     assert(super == NULL || super->super_depth() == i, "correct display");
 203     return super;
 204   }
 205 
 206   // Can this klass be a primary super?  False for interfaces and arrays of
 207   // interfaces.  False also for arrays or classes with long super chains.
 208   bool can_be_primary_super() const {
 209     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 210     return super_check_offset() != secondary_offset;
 211   }
 212   virtual bool can_be_primary_super_slow() const;
 213 
 214   // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
 215   juint super_depth() const {
 216     if (!can_be_primary_super()) {
 217       return primary_super_limit();
 218     } else {
 219       juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
 220       assert(d < primary_super_limit(), "oob");
 221       assert(_primary_supers[d] == this, "proper init");
 222       return d;
 223     }
 224   }
 225 
 226   // store an oop into a field of a Klass
 227   void klass_oop_store(oop* p, oop v);
 228   void klass_oop_store(volatile oop* p, oop v);
 229 
 230   // java mirror
 231   oop java_mirror() const              { return _java_mirror; }
 232   void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
 233 
 234   // modifier flags
 235   jint modifier_flags() const          { return _modifier_flags; }
 236   void set_modifier_flags(jint flags)  { _modifier_flags = flags; }
 237 
 238   // size helper
 239   int layout_helper() const            { return _layout_helper; }
 240   void set_layout_helper(int lh)       { _layout_helper = lh; }
 241 
 242   // Note: for instances layout_helper() may include padding.
 243   // Use InstanceKlass::contains_field_offset to classify field offsets.
 244 
 245   // sub/superklass links
 246   Klass* subklass() const              { return _subklass; }
 247   Klass* next_sibling() const          { return _next_sibling; }
 248   InstanceKlass* superklass() const;
 249   void append_to_sibling_list();           // add newly created receiver to superklass' subklass list
 250 
 251   void set_next_link(Klass* k) { _next_link = k; }
 252   Klass* next_link() const { return _next_link; }   // The next klass defined by the class loader.
 253 
 254   // class loader data
 255   ClassLoaderData* class_loader_data() const               { return _class_loader_data; }
 256   void set_class_loader_data(ClassLoaderData* loader_data) {  _class_loader_data = loader_data; }
 257 
 258   // The Klasses are not placed in the Heap, so the Card Table or
 259   // the Mod Union Table can't be used to mark when klasses have modified oops.
 260   // The CT and MUT bits saves this information for the individual Klasses.
 261   void record_modified_oops()            { _modified_oops = 1; }
 262   void clear_modified_oops()             { _modified_oops = 0; }
 263   bool has_modified_oops()               { return _modified_oops == 1; }
 264 
 265   void accumulate_modified_oops()        { if (has_modified_oops()) _accumulated_modified_oops = 1; }
 266   void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
 267   bool has_accumulated_modified_oops()   { return _accumulated_modified_oops == 1; }
 268 
 269   int shared_classpath_index() const   {
 270     return _shared_class_path_index;
 271   };
 272 
 273   void set_shared_classpath_index(int index) {
 274     _shared_class_path_index = index;
 275   };
 276 
 277 
 278  protected:                                // internal accessors
 279   void     set_subklass(Klass* s);
 280   void     set_next_sibling(Klass* s);
 281 
 282  public:
 283 
 284   // Compiler support
 285   static ByteSize super_offset()                 { return in_ByteSize(offset_of(Klass, _super)); }
 286   static ByteSize super_check_offset_offset()    { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
 287   static ByteSize primary_supers_offset()        { return in_ByteSize(offset_of(Klass, _primary_supers)); }
 288   static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
 289   static ByteSize secondary_supers_offset()      { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
 290   static ByteSize java_mirror_offset()           { return in_ByteSize(offset_of(Klass, _java_mirror)); }
 291   static ByteSize modifier_flags_offset()        { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
 292   static ByteSize layout_helper_offset()         { return in_ByteSize(offset_of(Klass, _layout_helper)); }
 293   static ByteSize access_flags_offset()          { return in_ByteSize(offset_of(Klass, _access_flags)); }
 294 
 295   // Unpacking layout_helper:
 296   enum {
 297     _lh_neutral_value           = 0,  // neutral non-array non-instance value
 298     _lh_instance_slow_path_bit  = 0x01,
 299     _lh_log2_element_size_shift = BitsPerByte*0,
 300     _lh_log2_element_size_mask  = BitsPerLong-1,
 301     _lh_element_type_shift      = BitsPerByte*1,
 302     _lh_element_type_mask       = right_n_bits(BitsPerByte),  // shifted mask
 303     _lh_header_size_shift       = BitsPerByte*2,
 304     _lh_header_size_mask        = right_n_bits(BitsPerByte),  // shifted mask
 305     _lh_array_tag_bits          = 2,
 306     _lh_array_tag_shift         = BitsPerInt - _lh_array_tag_bits,
 307     _lh_array_tag_type_value    = ~0x00,  // 0xC0000000 >> 30
 308     _lh_array_tag_obj_value     = ~0x01   // 0x80000000 >> 30
 309   };
 310 
 311   static int layout_helper_size_in_bytes(jint lh) {
 312     assert(lh > (jint)_lh_neutral_value, "must be instance");
 313     return (int) lh & ~_lh_instance_slow_path_bit;
 314   }
 315   static bool layout_helper_needs_slow_path(jint lh) {
 316     assert(lh > (jint)_lh_neutral_value, "must be instance");
 317     return (lh & _lh_instance_slow_path_bit) != 0;
 318   }
 319   static bool layout_helper_is_instance(jint lh) {
 320     return (jint)lh > (jint)_lh_neutral_value;
 321   }
 322   static bool layout_helper_is_array(jint lh) {
 323     return (jint)lh < (jint)_lh_neutral_value;
 324   }
 325   static bool layout_helper_is_typeArray(jint lh) {
 326     // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
 327     return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
 328   }
 329   static bool layout_helper_is_objArray(jint lh) {
 330     // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
 331     return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
 332   }
 333   static int layout_helper_header_size(jint lh) {
 334     assert(lh < (jint)_lh_neutral_value, "must be array");
 335     int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
 336     assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
 337     return hsize;
 338   }
 339   static BasicType layout_helper_element_type(jint lh) {
 340     assert(lh < (jint)_lh_neutral_value, "must be array");
 341     int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
 342     assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
 343     return (BasicType) btvalue;
 344   }
 345   static int layout_helper_log2_element_size(jint lh) {
 346     assert(lh < (jint)_lh_neutral_value, "must be array");
 347     int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
 348     assert(l2esz <= LogBitsPerLong,
 349         err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh));
 350     return l2esz;
 351   }
 352   static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
 353     return (tag        << _lh_array_tag_shift)
 354       |    (hsize      << _lh_header_size_shift)
 355       |    ((int)etype << _lh_element_type_shift)
 356       |    (log2_esize << _lh_log2_element_size_shift);
 357   }
 358   static jint instance_layout_helper(jint size, bool slow_path_flag) {
 359     return (size << LogHeapWordSize)
 360       |    (slow_path_flag ? _lh_instance_slow_path_bit : 0);
 361   }
 362   static int layout_helper_to_size_helper(jint lh) {
 363     assert(lh > (jint)_lh_neutral_value, "must be instance");
 364     // Note that the following expression discards _lh_instance_slow_path_bit.
 365     return lh >> LogHeapWordSize;
 366   }
 367   // Out-of-line version computes everything based on the etype:
 368   static jint array_layout_helper(BasicType etype);
 369 
 370   // What is the maximum number of primary superclasses any klass can have?
 371 #ifdef PRODUCT
 372   static juint primary_super_limit()         { return _primary_super_limit; }
 373 #else
 374   static juint primary_super_limit() {
 375     assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
 376     return FastSuperclassLimit;
 377   }
 378 #endif
 379 
 380   // vtables
 381   virtual klassVtable* vtable() const        { return NULL; }
 382   virtual int vtable_length() const          { return 0; }
 383 
 384   // subclass check
 385   bool is_subclass_of(const Klass* k) const;
 386   // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
 387   bool is_subtype_of(Klass* k) const {
 388     juint    off = k->super_check_offset();
 389     Klass* sup = *(Klass**)( (address)this + off );
 390     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 391     if (sup == k) {
 392       return true;
 393     } else if (off != secondary_offset) {
 394       return false;
 395     } else {
 396       return search_secondary_supers(k);
 397     }
 398   }
 399   bool search_secondary_supers(Klass* k) const;
 400 
 401   // Find LCA in class hierarchy
 402   Klass *LCA( Klass *k );
 403 
 404   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
 405   // if not, throw either an Error or an Exception.
 406   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
 407 
 408   // array copying
 409   virtual void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
 410 
 411   // tells if the class should be initialized
 412   virtual bool should_be_initialized() const    { return false; }
 413   // initializes the klass
 414   virtual void initialize(TRAPS);
 415   // lookup operation for MethodLookupCache
 416   friend class MethodLookupCache;
 417   virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
 418   virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature, OverpassLookupMode overpass_mode) const;
 419  public:
 420   Method* lookup_method(Symbol* name, Symbol* signature) const {
 421     return uncached_lookup_method(name, signature, find_overpass);
 422   }
 423 
 424   // array class with specific rank
 425   Klass* array_klass(int rank, TRAPS)         {  return array_klass_impl(false, rank, THREAD); }
 426 
 427   // array class with this klass as element type
 428   Klass* array_klass(TRAPS)                   {  return array_klass_impl(false, THREAD); }
 429 
 430   // These will return NULL instead of allocating on the heap:
 431   // NB: these can block for a mutex, like other functions with TRAPS arg.
 432   Klass* array_klass_or_null(int rank);
 433   Klass* array_klass_or_null();
 434 
 435   virtual oop protection_domain() const = 0;
 436 
 437   oop class_loader() const;
 438 
 439   virtual oop klass_holder() const      { return class_loader(); }
 440 
 441  protected:
 442   virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
 443   virtual Klass* array_klass_impl(bool or_null, TRAPS);
 444 
 445  public:
 446   // CDS support - remove and restore oops from metadata. Oops are not shared.
 447   virtual void remove_unshareable_info();
 448   virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
 449 
 450  protected:
 451   // computes the subtype relationship
 452   virtual bool compute_is_subtype_of(Klass* k);
 453  public:
 454   // subclass accessor (here for convenience; undefined for non-klass objects)
 455   virtual bool is_leaf_class() const { fatal("not a class"); return false; }
 456  public:
 457   // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
 458   // These functions describe behavior for the oop not the KLASS.
 459 
 460   // actual oop size of obj in memory
 461   virtual int oop_size(oop obj) const = 0;
 462 
 463   // Size of klass in word size.
 464   virtual int size() const = 0;
 465 #if INCLUDE_SERVICES
 466   virtual void collect_statistics(KlassSizeStats *sz) const;
 467 #endif
 468 
 469   // Returns the Java name for a class (Resource allocated)
 470   // For arrays, this returns the name of the element with a leading '['.
 471   // For classes, this returns the name with the package separators
 472   //     turned into '.'s.
 473   const char* external_name() const;
 474   // Returns the name for a class (Resource allocated) as the class
 475   // would appear in a signature.
 476   // For arrays, this returns the name of the element with a leading '['.
 477   // For classes, this returns the name with a leading 'L' and a trailing ';'
 478   //     and the package separators as '/'.
 479   virtual const char* signature_name() const;
 480 
 481   // garbage collection support
 482   virtual void oop_follow_contents(oop obj) = 0;
 483   virtual int  oop_adjust_pointers(oop obj) = 0;
 484 
 485   // Parallel Scavenge and Parallel Old
 486   PARALLEL_GC_DECLS_PV
 487 
 488   // type testing operations
 489  protected:
 490   virtual bool oop_is_instance_slow()       const { return false; }
 491   virtual bool oop_is_array_slow()          const { return false; }
 492   virtual bool oop_is_objArray_slow()       const { return false; }
 493   virtual bool oop_is_typeArray_slow()      const { return false; }
 494  public:
 495   virtual bool oop_is_instanceClassLoader() const { return false; }
 496   virtual bool oop_is_instanceMirror()      const { return false; }
 497   virtual bool oop_is_instanceRef()         const { return false; }
 498 
 499   // Fast non-virtual versions
 500   #ifndef ASSERT
 501   #define assert_same_query(xval, xcheck) xval
 502   #else
 503  private:
 504   static bool assert_same_query(bool xval, bool xslow) {
 505     assert(xval == xslow, "slow and fast queries agree");
 506     return xval;
 507   }
 508  public:
 509   #endif
 510   inline  bool oop_is_instance()            const { return assert_same_query(
 511                                                     layout_helper_is_instance(layout_helper()),
 512                                                     oop_is_instance_slow()); }
 513   inline  bool oop_is_array()               const { return assert_same_query(
 514                                                     layout_helper_is_array(layout_helper()),
 515                                                     oop_is_array_slow()); }
 516   inline  bool oop_is_objArray()            const { return assert_same_query(
 517                                                     layout_helper_is_objArray(layout_helper()),
 518                                                     oop_is_objArray_slow()); }
 519   inline  bool oop_is_typeArray()           const { return assert_same_query(
 520                                                     layout_helper_is_typeArray(layout_helper()),
 521                                                     oop_is_typeArray_slow()); }
 522   #undef assert_same_query
 523 
 524   // Access flags
 525   AccessFlags access_flags() const         { return _access_flags;  }
 526   void set_access_flags(AccessFlags flags) { _access_flags = flags; }
 527 
 528   bool is_public() const                { return _access_flags.is_public(); }
 529   bool is_final() const                 { return _access_flags.is_final(); }
 530   bool is_interface() const             { return _access_flags.is_interface(); }
 531   bool is_abstract() const              { return _access_flags.is_abstract(); }
 532   bool is_super() const                 { return _access_flags.is_super(); }
 533   bool is_synthetic() const             { return _access_flags.is_synthetic(); }
 534   void set_is_synthetic()               { _access_flags.set_is_synthetic(); }
 535   bool has_finalizer() const            { return _access_flags.has_finalizer(); }
 536   bool has_final_method() const         { return _access_flags.has_final_method(); }
 537   void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
 538   void set_has_final_method()           { _access_flags.set_has_final_method(); }
 539   bool is_cloneable() const             { return _access_flags.is_cloneable(); }
 540   void set_is_cloneable()               { _access_flags.set_is_cloneable(); }
 541   bool has_vanilla_constructor() const  { return _access_flags.has_vanilla_constructor(); }
 542   void set_has_vanilla_constructor()    { _access_flags.set_has_vanilla_constructor(); }
 543   bool has_miranda_methods () const     { return access_flags().has_miranda_methods(); }
 544   void set_has_miranda_methods()        { _access_flags.set_has_miranda_methods(); }
 545 
 546   // Biased locking support
 547   // Note: the prototype header is always set up to be at least the
 548   // prototype markOop. If biased locking is enabled it may further be
 549   // biasable and have an epoch.
 550   markOop prototype_header() const      { return _prototype_header; }
 551   // NOTE: once instances of this klass are floating around in the
 552   // system, this header must only be updated at a safepoint.
 553   // NOTE 2: currently we only ever set the prototype header to the
 554   // biasable prototype for instanceKlasses. There is no technical
 555   // reason why it could not be done for arrayKlasses aside from
 556   // wanting to reduce the initial scope of this optimization. There
 557   // are potential problems in setting the bias pattern for
 558   // JVM-internal oops.
 559   inline void set_prototype_header(markOop header);
 560   static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
 561 
 562   int  biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
 563   // Atomically increments biased_lock_revocation_count and returns updated value
 564   int atomic_incr_biased_lock_revocation_count();
 565   void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
 566   jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
 567   void  set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
 568 
 569   TRACE_DEFINE_KLASS_METHODS;
 570 
 571   // garbage collection support
 572   void oops_do(OopClosure* cl);
 573 
 574   // Iff the class loader (or mirror for anonymous classes) is alive the
 575   // Klass is considered alive.
 576   // The is_alive closure passed in depends on the Garbage Collector used.
 577   bool is_loader_alive(BoolObjectClosure* is_alive);
 578 
 579   static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
 580   static void clean_subklass_tree(BoolObjectClosure* is_alive) {
 581     clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
 582   }
 583 
 584   // iterators
 585   virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0;
 586   virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) {
 587     return oop_oop_iterate(obj, blk);
 588   }
 589 
 590 #if INCLUDE_ALL_GCS
 591   // In case we don't have a specialized backward scanner use forward
 592   // iteration.
 593   virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) {
 594     return oop_oop_iterate_v(obj, blk);
 595   }
 596 #endif // INCLUDE_ALL_GCS
 597 
 598   // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
 599   // (I don't see why the _m should be required, but without it the Solaris
 600   // C++ gives warning messages about overridings of the "oop_oop_iterate"
 601   // defined above "hiding" this virtual function.  (DLD, 6/20/00)) */
 602   virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0;
 603   virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
 604     return oop_oop_iterate_m(obj, blk, mr);
 605   }
 606 
 607   // Versions of the above iterators specialized to particular subtypes
 608   // of OopClosure, to avoid closure virtual calls.
 609 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                \
 610   virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) {     \
 611     /* Default implementation reverts to general version. */                 \
 612     return oop_oop_iterate(obj, blk);                                        \
 613   }                                                                          \
 614                                                                              \
 615   /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
 616      (I don't see why the _m should be required, but without it the Solaris  \
 617      C++ gives warning messages about overridings of the "oop_oop_iterate"   \
 618      defined above "hiding" this virtual function.  (DLD, 6/20/00)) */       \
 619   virtual int oop_oop_iterate##nv_suffix##_m(oop obj,                        \
 620                                              OopClosureType* blk,            \
 621                                              MemRegion mr) {                 \
 622     return oop_oop_iterate_m(obj, blk, mr);                                  \
 623   }
 624 
 625   SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
 626   SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
 627 
 628 #if INCLUDE_ALL_GCS
 629 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)      \
 630   virtual int oop_oop_iterate_backwards##nv_suffix(oop obj,                  \
 631                                                    OopClosureType* blk) {    \
 632     /* Default implementation reverts to general version. */                 \
 633     return oop_oop_iterate_backwards_v(obj, blk);                            \
 634   }
 635 
 636   SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 637   SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 638 #endif // INCLUDE_ALL_GCS
 639 
 640   virtual void array_klasses_do(void f(Klass* k)) {}
 641 
 642   // Return self, except for abstract classes with exactly 1
 643   // implementor.  Then return the 1 concrete implementation.
 644   Klass *up_cast_abstract();
 645 
 646   // klass name
 647   Symbol* name() const                   { return _name; }
 648   void set_name(Symbol* n);
 649 
 650  public:
 651   // jvm support
 652   virtual jint compute_modifier_flags(TRAPS) const;
 653 
 654   // JVMTI support
 655   virtual jint jvmti_class_status() const;
 656 
 657   // Printing
 658   virtual void print_on(outputStream* st) const;
 659 
 660   virtual void oop_print_value_on(oop obj, outputStream* st);
 661   virtual void oop_print_on      (oop obj, outputStream* st);
 662 
 663   virtual const char* internal_name() const = 0;
 664 
 665   // Verification
 666   virtual void verify_on(outputStream* st);
 667   void verify() { verify_on(tty); }
 668 
 669 #ifndef PRODUCT
 670   bool verify_vtable_index(int index);
 671   bool verify_itable_index(int index);
 672 #endif
 673 
 674   virtual void oop_verify_on(oop obj, outputStream* st);
 675 
 676   static bool is_null(narrowKlass obj);
 677   static bool is_null(Klass* obj);
 678 
 679   // klass encoding for klass pointer in objects.
 680   static narrowKlass encode_klass_not_null(Klass* v);
 681   static narrowKlass encode_klass(Klass* v);
 682 
 683   static Klass* decode_klass_not_null(narrowKlass v);
 684   static Klass* decode_klass(narrowKlass v);
 685 
 686  private:
 687   // barriers used by klass_oop_store
 688   void klass_update_barrier_set(oop v);
 689   void klass_update_barrier_set_pre(oop* p, oop v);
 690 };
 691 
 692 #endif // SHARE_VM_OOPS_KLASS_HPP