1 /*
   2  * Copyright (c) 1997, 2016, 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 class vtableEntry;
  61 
  62 class Klass : public Metadata {
  63   friend class VMStructs;
  64   friend class JVMCIVMStructs;
  65  protected:
  66   // note: put frequently-used fields together at start of klass structure
  67   // for better cache behavior (may not make much of a difference but sure won't hurt)
  68   enum { _primary_super_limit = 8 };
  69 
  70   // The "layout helper" is a combined descriptor of object layout.
  71   // For klasses which are neither instance nor array, the value is zero.
  72   //
  73   // For instances, layout helper is a positive number, the instance size.
  74   // This size is already passed through align_object_size and scaled to bytes.
  75   // The low order bit is set if instances of this class cannot be
  76   // allocated using the fastpath.
  77   //
  78   // For arrays, layout helper is a negative number, containing four
  79   // distinct bytes, as follows:
  80   //    MSB:[tag, hsz, ebt, log2(esz)]:LSB
  81   // where:
  82   //    tag is 0x80 if the elements are oops, 0xC0 if non-oops
  83   //    hsz is array header size in bytes (i.e., offset of first element)
  84   //    ebt is the BasicType of the elements
  85   //    esz is the element size in bytes
  86   // This packed word is arranged so as to be quickly unpacked by the
  87   // various fast paths that use the various subfields.
  88   //
  89   // The esz bits can be used directly by a SLL instruction, without masking.
  90   //
  91   // Note that the array-kind tag looks like 0x00 for instance klasses,
  92   // since their length in bytes is always less than 24Mb.
  93   //
  94   // Final note:  This comes first, immediately after C++ vtable,
  95   // because it is frequently queried.
  96   jint        _layout_helper;
  97 
  98   // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
  99   // and _primary_supers all help make fast subtype checks.  See big discussion
 100   // in doc/server_compiler/checktype.txt
 101   //
 102   // Where to look to observe a supertype (it is &_secondary_super_cache for
 103   // secondary supers, else is &_primary_supers[depth()].
 104   juint       _super_check_offset;
 105 
 106   // Class name.  Instance classes: java/lang/String, etc.  Array classes: [I,
 107   // [Ljava/lang/String;, etc.  Set to zero for all other kinds of classes.
 108   Symbol*     _name;
 109 
 110   // Cache of last observed secondary supertype
 111   Klass*      _secondary_super_cache;
 112   // Array of all secondary supertypes
 113   Array<Klass*>* _secondary_supers;
 114   // Ordered list of all primary supertypes
 115   Klass*      _primary_supers[_primary_super_limit];
 116   // java/lang/Class instance mirroring this class
 117   oop       _java_mirror;
 118   // Superclass
 119   Klass*      _super;
 120   // First subclass (NULL if none); _subklass->next_sibling() is next one
 121   Klass*      _subklass;
 122   // Sibling link (or NULL); links all subklasses of a klass
 123   Klass*      _next_sibling;
 124 
 125   // All klasses loaded by a class loader are chained through these links
 126   Klass*      _next_link;
 127 
 128   // The VM's representation of the ClassLoader used to load this class.
 129   // Provide access the corresponding instance java.lang.ClassLoader.
 130   ClassLoaderData* _class_loader_data;
 131 
 132   jint        _modifier_flags;  // Processed access flags, for use by Class.getModifiers.
 133   AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.
 134 
 135   TRACE_DEFINE_TRACE_ID_FIELD;
 136 
 137   // Biased locking implementation and statistics
 138   // (the 64-bit chunk goes first, to avoid some fragmentation)
 139   jlong    _last_biased_lock_bulk_revocation_time;
 140   markOop  _prototype_header;   // Used when biased locking is both enabled and disabled for this type
 141   jint     _biased_lock_revocation_count;
 142 
 143   // vtable length
 144   int _vtable_len;
 145 
 146   // Remembered sets support for the oops in the klasses.
 147   jbyte _modified_oops;             // Card Table Equivalent (YC/CMS support)
 148   jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
 149 
 150 private:
 151   // This is an index into FileMapHeader::_classpath_entry_table[], to
 152   // associate this class with the JAR file where it's loaded from during
 153   // dump time. If a class is not loaded from the shared archive, this field is
 154   // -1.
 155   jshort _shared_class_path_index;
 156 
 157   friend class SharedClassUtil;
 158 protected:
 159 
 160   // Constructor
 161   Klass();
 162 
 163   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw();
 164 
 165  public:
 166   enum DefaultsLookupMode { find_defaults, skip_defaults };
 167   enum OverpassLookupMode { find_overpass, skip_overpass };
 168   enum StaticLookupMode   { find_static,   skip_static };
 169   enum PrivateLookupMode  { find_private,  skip_private };
 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 const juint _lh_array_bit = 1 << (BitsPerInt - 1); // 0x80000000
 312 
 313   static int layout_helper_size_in_bytes(jint lh) {
 314     assert(lh > (jint)_lh_neutral_value, "must be instance");
 315     return (int) lh & ~_lh_instance_slow_path_bit;
 316   }
 317   static bool layout_helper_needs_slow_path(jint lh) {
 318     assert(lh > (jint)_lh_neutral_value, "must be instance");
 319     return (lh & _lh_instance_slow_path_bit) != 0;
 320   }
 321   static bool layout_helper_is_instance(jint lh) {
 322     return (jint)lh > (jint)_lh_neutral_value;
 323   }
 324   static bool layout_helper_is_array(jint lh) {
 325     return (jint)lh < (jint)_lh_neutral_value;
 326   }
 327   static bool layout_helper_is_typeArray(jint lh) {
 328     // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
 329     return (juint)lh >= (juint)(uint(_lh_array_tag_type_value) << _lh_array_tag_shift);
 330   }
 331   static bool layout_helper_is_objArray(jint lh) {
 332     // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
 333     return (jint)lh < (jint)(uint(_lh_array_tag_type_value) << _lh_array_tag_shift);
 334   }
 335   static int layout_helper_header_size(jint lh) {
 336     assert(lh < (jint)_lh_neutral_value, "must be array");
 337     int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
 338     assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
 339     return hsize;
 340   }
 341   static BasicType layout_helper_element_type(jint lh) {
 342     assert(lh < (jint)_lh_neutral_value, "must be array");
 343     int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
 344     assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
 345     return (BasicType) btvalue;
 346   }
 347   static int layout_helper_log2_element_size(jint lh) {
 348     assert(lh < (jint)_lh_neutral_value, "must be array");
 349     int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
 350     assert(l2esz <= LogBitsPerLong,
 351            "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
 352     return l2esz;
 353   }
 354   static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
 355     return (tag        << _lh_array_tag_shift)
 356       |    (hsize      << _lh_header_size_shift)
 357       |    ((int)etype << _lh_element_type_shift)
 358       |    (log2_esize << _lh_log2_element_size_shift);
 359   }
 360   static jint instance_layout_helper(jint size, bool slow_path_flag) {
 361     return (size << LogBytesPerWord)
 362       |    (slow_path_flag ? _lh_instance_slow_path_bit : 0);
 363   }
 364   static int layout_helper_to_size_helper(jint lh) {
 365     assert(lh > (jint)_lh_neutral_value, "must be instance");
 366     // Note that the following expression discards _lh_instance_slow_path_bit.
 367     return lh >> LogBytesPerWord;
 368   }
 369   // Out-of-line version computes everything based on the etype:
 370   static jint array_layout_helper(BasicType etype);
 371 
 372   // What is the maximum number of primary superclasses any klass can have?
 373 #ifdef PRODUCT
 374   static juint primary_super_limit()         { return _primary_super_limit; }
 375 #else
 376   static juint primary_super_limit() {
 377     assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
 378     return FastSuperclassLimit;
 379   }
 380 #endif
 381 
 382   // vtables
 383   klassVtable* vtable() const;
 384   int vtable_length() const { return _vtable_len; }
 385 
 386   // subclass check
 387   bool is_subclass_of(const Klass* k) const;
 388   // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
 389   bool is_subtype_of(Klass* k) const {
 390     juint    off = k->super_check_offset();
 391     Klass* sup = *(Klass**)( (address)this + off );
 392     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 393     if (sup == k) {
 394       return true;
 395     } else if (off != secondary_offset) {
 396       return false;
 397     } else {
 398       return search_secondary_supers(k);
 399     }
 400   }
 401   bool search_secondary_supers(Klass* k) const;
 402 
 403   // Find LCA in class hierarchy
 404   Klass *LCA( Klass *k );
 405 
 406   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
 407   // if not, throw either an Error or an Exception.
 408   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
 409 
 410   // array copying
 411   virtual void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
 412 
 413   // tells if the class should be initialized
 414   virtual bool should_be_initialized() const    { return false; }
 415   // initializes the klass
 416   virtual void initialize(TRAPS);
 417   // lookup operation for MethodLookupCache
 418   friend class MethodLookupCache;
 419   virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
 420   virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature, OverpassLookupMode overpass_mode) const;
 421  public:
 422   Method* lookup_method(const Symbol* name, const Symbol* signature) const {
 423     return uncached_lookup_method(name, signature, find_overpass);
 424   }
 425 
 426   // array class with specific rank
 427   Klass* array_klass(int rank, TRAPS)         {  return array_klass_impl(false, rank, THREAD); }
 428 
 429   // array class with this klass as element type
 430   Klass* array_klass(TRAPS)                   {  return array_klass_impl(false, THREAD); }
 431 
 432   // These will return NULL instead of allocating on the heap:
 433   // NB: these can block for a mutex, like other functions with TRAPS arg.
 434   Klass* array_klass_or_null(int rank);
 435   Klass* array_klass_or_null();
 436 
 437   virtual oop protection_domain() const = 0;
 438 
 439   oop class_loader() const;
 440 
 441   virtual oop klass_holder() const      { return class_loader(); }
 442 
 443  protected:
 444   virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
 445   virtual Klass* array_klass_impl(bool or_null, TRAPS);
 446 
 447   void set_vtable_length(int len) { _vtable_len= len; }
 448 
 449   vtableEntry* start_of_vtable() const;
 450  public:
 451   Method* method_at_vtable(int index);
 452 
 453   static ByteSize vtable_start_offset();
 454   static ByteSize vtable_length_offset() {
 455     return byte_offset_of(Klass, _vtable_len);
 456   }
 457 
 458   // CDS support - remove and restore oops from metadata. Oops are not shared.
 459   virtual void remove_unshareable_info();
 460   virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
 461 
 462  protected:
 463   // computes the subtype relationship
 464   virtual bool compute_is_subtype_of(Klass* k);
 465  public:
 466   // subclass accessor (here for convenience; undefined for non-klass objects)
 467   virtual bool is_leaf_class() const { fatal("not a class"); return false; }
 468  public:
 469   // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
 470   // These functions describe behavior for the oop not the KLASS.
 471 
 472   // actual oop size of obj in memory
 473   virtual int oop_size(oop obj) const = 0;
 474 
 475   // Size of klass in word size.
 476   virtual int size() const = 0;
 477 #if INCLUDE_SERVICES
 478   virtual void collect_statistics(KlassSizeStats *sz) const;
 479 #endif
 480 
 481   // Returns the Java name for a class (Resource allocated)
 482   // For arrays, this returns the name of the element with a leading '['.
 483   // For classes, this returns the name with the package separators
 484   //     turned into '.'s.
 485   const char* external_name() const;
 486   // Returns the name for a class (Resource allocated) as the class
 487   // would appear in a signature.
 488   // For arrays, this returns the name of the element with a leading '['.
 489   // For classes, this returns the name with a leading 'L' and a trailing ';'
 490   //     and the package separators as '/'.
 491   virtual const char* signature_name() const;
 492 
 493   // type testing operations
 494 #ifdef ASSERT
 495  protected:
 496   virtual bool is_instance_klass_slow()     const { return false; }
 497   virtual bool is_array_klass_slow()        const { return false; }
 498   virtual bool is_objArray_klass_slow()     const { return false; }
 499   virtual bool is_typeArray_klass_slow()    const { return false; }
 500 #endif // ASSERT
 501  public:
 502 
 503   // Fast non-virtual versions
 504   #ifndef ASSERT
 505   #define assert_same_query(xval, xcheck) xval
 506   #else
 507  private:
 508   static bool assert_same_query(bool xval, bool xslow) {
 509     assert(xval == xslow, "slow and fast queries agree");
 510     return xval;
 511   }
 512  public:
 513   #endif
 514   inline  bool is_instance_klass()            const { return assert_same_query(
 515                                                       layout_helper_is_instance(layout_helper()),
 516                                                       is_instance_klass_slow()); }
 517   inline  bool is_array_klass()               const { return assert_same_query(
 518                                                     layout_helper_is_array(layout_helper()),
 519                                                     is_array_klass_slow()); }
 520   inline  bool is_objArray_klass()            const { return assert_same_query(
 521                                                     layout_helper_is_objArray(layout_helper()),
 522                                                     is_objArray_klass_slow()); }
 523   inline  bool is_typeArray_klass()           const { return assert_same_query(
 524                                                     layout_helper_is_typeArray(layout_helper()),
 525                                                     is_typeArray_klass_slow()); }
 526   #undef assert_same_query
 527 
 528   // Access flags
 529   AccessFlags access_flags() const         { return _access_flags;  }
 530   void set_access_flags(AccessFlags flags) { _access_flags = flags; }
 531 
 532   bool is_public() const                { return _access_flags.is_public(); }
 533   bool is_final() const                 { return _access_flags.is_final(); }
 534   bool is_interface() const             { return _access_flags.is_interface(); }
 535   bool is_abstract() const              { return _access_flags.is_abstract(); }
 536   bool is_super() const                 { return _access_flags.is_super(); }
 537   bool is_synthetic() const             { return _access_flags.is_synthetic(); }
 538   void set_is_synthetic()               { _access_flags.set_is_synthetic(); }
 539   bool has_finalizer() const            { return _access_flags.has_finalizer(); }
 540   bool has_final_method() const         { return _access_flags.has_final_method(); }
 541   void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
 542   void set_has_final_method()           { _access_flags.set_has_final_method(); }
 543   bool has_vanilla_constructor() const  { return _access_flags.has_vanilla_constructor(); }
 544   void set_has_vanilla_constructor()    { _access_flags.set_has_vanilla_constructor(); }
 545   bool has_miranda_methods () const     { return access_flags().has_miranda_methods(); }
 546   void set_has_miranda_methods()        { _access_flags.set_has_miranda_methods(); }
 547 
 548   bool is_cloneable() const;
 549   void set_is_cloneable();
 550 
 551   // Biased locking support
 552   // Note: the prototype header is always set up to be at least the
 553   // prototype markOop. If biased locking is enabled it may further be
 554   // biasable and have an epoch.
 555   markOop prototype_header() const      { return _prototype_header; }
 556   // NOTE: once instances of this klass are floating around in the
 557   // system, this header must only be updated at a safepoint.
 558   // NOTE 2: currently we only ever set the prototype header to the
 559   // biasable prototype for instanceKlasses. There is no technical
 560   // reason why it could not be done for arrayKlasses aside from
 561   // wanting to reduce the initial scope of this optimization. There
 562   // are potential problems in setting the bias pattern for
 563   // JVM-internal oops.
 564   inline void set_prototype_header(markOop header);
 565   static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
 566 
 567   int  biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
 568   // Atomically increments biased_lock_revocation_count and returns updated value
 569   int atomic_incr_biased_lock_revocation_count();
 570   void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
 571   jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
 572   void  set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
 573 
 574   TRACE_DEFINE_TRACE_ID_METHODS;
 575 
 576   // garbage collection support
 577   void oops_do(OopClosure* cl);
 578 
 579   // Iff the class loader (or mirror for anonymous classes) is alive the
 580   // Klass is considered alive.
 581   // The is_alive closure passed in depends on the Garbage Collector used.
 582   bool is_loader_alive(BoolObjectClosure* is_alive);
 583 
 584   static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
 585   static void clean_subklass_tree(BoolObjectClosure* is_alive) {
 586     clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
 587   }
 588 
 589   // GC specific object visitors
 590   //
 591   // Mark Sweep
 592   virtual int  oop_ms_adjust_pointers(oop obj) = 0;
 593 #if INCLUDE_ALL_GCS
 594   // Parallel Scavenge
 595   virtual void oop_ps_push_contents(  oop obj, PSPromotionManager* pm)   = 0;
 596   // Parallel Compact
 597   virtual void oop_pc_follow_contents(oop obj, ParCompactionManager* cm) = 0;
 598   virtual void oop_pc_update_pointers(oop obj, ParCompactionManager* cm) = 0;
 599 #endif
 600 
 601   // Iterators specialized to particular subtypes
 602   // of ExtendedOopClosure, to avoid closure virtual calls.
 603 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                           \
 604   virtual void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) = 0;                        \
 605   /* Iterates "closure" over all the oops in "obj" (of type "this") within "mr". */                     \
 606   virtual void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) = 0;
 607 
 608   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
 609   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
 610 
 611 #if INCLUDE_ALL_GCS
 612 #define Klass_OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix)                     \
 613   virtual void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) = 0;
 614 
 615   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
 616   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
 617 #endif // INCLUDE_ALL_GCS
 618 
 619   virtual void array_klasses_do(void f(Klass* k)) {}
 620 
 621   // Return self, except for abstract classes with exactly 1
 622   // implementor.  Then return the 1 concrete implementation.
 623   Klass *up_cast_abstract();
 624 
 625   // klass name
 626   Symbol* name() const                   { return _name; }
 627   void set_name(Symbol* n);
 628 
 629  public:
 630   // jvm support
 631   virtual jint compute_modifier_flags(TRAPS) const;
 632 
 633   // JVMTI support
 634   virtual jint jvmti_class_status() const;
 635 
 636   // Printing
 637   virtual void print_on(outputStream* st) const;
 638 
 639   virtual void oop_print_value_on(oop obj, outputStream* st);
 640   virtual void oop_print_on      (oop obj, outputStream* st);
 641 
 642   virtual const char* internal_name() const = 0;
 643 
 644   // Verification
 645   virtual void verify_on(outputStream* st);
 646   void verify() { verify_on(tty); }
 647 
 648 #ifndef PRODUCT
 649   bool verify_vtable_index(int index);
 650   bool verify_itable_index(int index);
 651 #endif
 652 
 653   virtual void oop_verify_on(oop obj, outputStream* st);
 654 
 655   static bool is_null(narrowKlass obj);
 656   static bool is_null(Klass* obj);
 657 
 658   // klass encoding for klass pointer in objects.
 659   static narrowKlass encode_klass_not_null(Klass* v);
 660   static narrowKlass encode_klass(Klass* v);
 661 
 662   static Klass* decode_klass_not_null(narrowKlass v);
 663   static Klass* decode_klass(narrowKlass v);
 664 
 665  private:
 666   // barriers used by klass_oop_store
 667   void klass_update_barrier_set(oop v);
 668   void klass_update_barrier_set_pre(oop* p, oop v);
 669 };
 670 
 671 // Helper to convert the oop iterate macro suffixes into bool values that can be used by template functions.
 672 #define nvs_nv_to_bool true
 673 #define nvs_v_to_bool  false
 674 #define nvs_to_bool(nv_suffix) nvs##nv_suffix##_to_bool
 675 
 676 // Oop iteration macros for declarations.
 677 // Used to generate declarations in the *Klass header files.
 678 
 679 #define OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                    \
 680   void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure);                        \
 681   void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr);
 682 
 683 #if INCLUDE_ALL_GCS
 684 #define OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix)               \
 685   void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure);
 686 #endif // INCLUDE_ALL_GCS
 687 
 688 
 689 // Oop iteration macros for definitions.
 690 // Used to generate definitions in the *Klass.inline.hpp files.
 691 
 692 #define OOP_OOP_ITERATE_DEFN(KlassType, OopClosureType, nv_suffix)              \
 693 void KlassType::oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) {  \
 694   oop_oop_iterate<nvs_to_bool(nv_suffix)>(obj, closure);                        \
 695 }
 696 
 697 #if INCLUDE_ALL_GCS
 698 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)              \
 699 void KlassType::oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) {  \
 700   oop_oop_iterate_reverse<nvs_to_bool(nv_suffix)>(obj, closure);                          \
 701 }
 702 #else
 703 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)
 704 #endif
 705 
 706 #define OOP_OOP_ITERATE_DEFN_BOUNDED(KlassType, OopClosureType, nv_suffix)                            \
 707 void KlassType::oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) {  \
 708   oop_oop_iterate_bounded<nvs_to_bool(nv_suffix)>(obj, closure, mr);                                  \
 709 }
 710 
 711 #endif // SHARE_VM_OOPS_KLASS_HPP