1 /*
   2  * Copyright (c) 1997, 2018, 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 "oops/oopHandle.hpp"
  34 #include "trace/traceMacros.hpp"
  35 #include "utilities/accessFlags.hpp"
  36 #include "utilities/macros.hpp"
  37 
  38 //
  39 // A Klass provides:
  40 //  1: language level class object (method dictionary etc.)
  41 //  2: provide vm dispatch behavior for the object
  42 // Both functions are combined into one C++ class.
  43 
  44 // One reason for the oop/klass dichotomy in the implementation is
  45 // that we don't want a C++ vtbl pointer in every object.  Thus,
  46 // normal oops don't have any virtual functions.  Instead, they
  47 // forward all "virtual" functions to their klass, which does have
  48 // a vtbl and does the C++ dispatch depending on the object's
  49 // actual type.  (See oop.inline.hpp for some of the forwarding code.)
  50 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
  51 
  52 // Forward declarations.
  53 template <class T> class Array;
  54 template <class T> class GrowableArray;
  55 class ClassLoaderData;
  56 class fieldDescriptor;
  57 class KlassSizeStats;
  58 class klassVtable;
  59 class ModuleEntry;
  60 class PackageEntry;
  61 class ParCompactionManager;
  62 class PSPromotionManager;
  63 class vtableEntry;
  64 
  65 class Klass : public Metadata {
  66   friend class VMStructs;
  67   friend class JVMCIVMStructs;
  68  protected:
  69   // If you add a new field that points to any metaspace object, you
  70   // must add this field to Klass::metaspace_pointers_do().
  71 
  72   // note: put frequently-used fields together at start of klass structure
  73   // for better cache behavior (may not make much of a difference but sure won't hurt)
  74   enum { _primary_super_limit = 8 };
  75 
  76   // The "layout helper" is a combined descriptor of object layout.
  77   // For klasses which are neither instance nor array, the value is zero.
  78   //
  79   // For instances, layout helper is a positive number, the instance size.
  80   // This size is already passed through align_object_size and scaled to bytes.
  81   // The low order bit is set if instances of this class cannot be
  82   // allocated using the fastpath.
  83   //
  84   // For arrays, layout helper is a negative number, containing four
  85   // distinct bytes, as follows:
  86   //    MSB:[tag, hsz, ebt, log2(esz)]:LSB
  87   // where:
  88   //    tag is 0x80 if the elements are oops, 0xC0 if non-oops, 0xA0 if value types
  89   //    hsz is array header size in bytes (i.e., offset of first element)
  90   //    ebt is the BasicType of the elements
  91   //    esz is the element size in bytes
  92   // This packed word is arranged so as to be quickly unpacked by the
  93   // various fast paths that use the various subfields.
  94   //
  95   // The esz bits can be used directly by a SLL instruction, without masking.
  96   //
  97   // Note that the array-kind tag looks like 0x00 for instance klasses,
  98   // since their length in bytes is always less than 24Mb.
  99   //
 100   // Final note:  This comes first, immediately after C++ vtable,
 101   // because it is frequently queried.
 102   jint        _layout_helper;
 103 
 104   // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
 105   // and _primary_supers all help make fast subtype checks.  See big discussion
 106   // in doc/server_compiler/checktype.txt
 107   //
 108   // Where to look to observe a supertype (it is &_secondary_super_cache for
 109   // secondary supers, else is &_primary_supers[depth()].
 110   juint       _super_check_offset;
 111 
 112   // Class name.  Instance classes: java/lang/String, etc.  Array classes: [I,
 113   // [Ljava/lang/String;, etc.  Set to zero for all other kinds of classes.
 114   Symbol*     _name;
 115 
 116   // Cache of last observed secondary supertype
 117   Klass*      _secondary_super_cache;
 118   // Array of all secondary supertypes
 119   Array<Klass*>* _secondary_supers;
 120   // Ordered list of all primary supertypes
 121   Klass*      _primary_supers[_primary_super_limit];
 122   // java/lang/Class instance mirroring this class
 123   OopHandle _java_mirror;
 124   // Superclass
 125   Klass*      _super;
 126   // First subclass (NULL if none); _subklass->next_sibling() is next one
 127   Klass*      _subklass;
 128   // Sibling link (or NULL); links all subklasses of a klass
 129   Klass*      _next_sibling;
 130 
 131   // All klasses loaded by a class loader are chained through these links
 132   Klass*      _next_link;
 133 
 134   // The VM's representation of the ClassLoader used to load this class.
 135   // Provide access the corresponding instance java.lang.ClassLoader.
 136   ClassLoaderData* _class_loader_data;
 137 
 138   jint        _modifier_flags;  // Processed access flags, for use by Class.getModifiers.
 139   AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.
 140 
 141   TRACE_DEFINE_TRACE_ID_FIELD;
 142 
 143   // Biased locking implementation and statistics
 144   // (the 64-bit chunk goes first, to avoid some fragmentation)
 145   jlong    _last_biased_lock_bulk_revocation_time;
 146   markOop  _prototype_header;   // Used when biased locking is both enabled and disabled for this type
 147   jint     _biased_lock_revocation_count;
 148 
 149   // vtable length
 150   int _vtable_len;
 151 
 152 private:
 153   // This is an index into FileMapHeader::_classpath_entry_table[], to
 154   // associate this class with the JAR file where it's loaded from during
 155   // dump time. If a class is not loaded from the shared archive, this field is
 156   // -1.
 157   jshort _shared_class_path_index;
 158 
 159   friend class SharedClassUtil;
 160 protected:
 161 
 162   // Constructor
 163   Klass();
 164 
 165   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, bool is_value, TRAPS) throw();
 166   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
 167    return operator new (size, loader_data, word_size, false, THREAD);
 168   }
 169 
 170  public:
 171   enum DefaultsLookupMode { find_defaults, skip_defaults };
 172   enum OverpassLookupMode { find_overpass, skip_overpass };
 173   enum StaticLookupMode   { find_static,   skip_static };
 174   enum PrivateLookupMode  { find_private,  skip_private };
 175 
 176   bool is_klass() const volatile { return true; }
 177 
 178   // super
 179   Klass* super() const               { return _super; }
 180   void set_super(Klass* k)           { _super = k; }
 181 
 182   // initializes _super link, _primary_supers & _secondary_supers arrays
 183   void initialize_supers(Klass* k, TRAPS);
 184   void initialize_supers_impl1(Klass* k);
 185   void initialize_supers_impl2(Klass* k);
 186 
 187   // klass-specific helper for initializing _secondary_supers
 188   virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
 189 
 190   // java_super is the Java-level super type as specified by Class.getSuperClass.
 191   virtual Klass* java_super() const  { return NULL; }
 192 
 193   juint    super_check_offset() const  { return _super_check_offset; }
 194   void set_super_check_offset(juint o) { _super_check_offset = o; }
 195 
 196   Klass* secondary_super_cache() const     { return _secondary_super_cache; }
 197   void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
 198 
 199   Array<Klass*>* secondary_supers() const { return _secondary_supers; }
 200   void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
 201 
 202   // Return the element of the _super chain of the given depth.
 203   // If there is no such element, return either NULL or this.
 204   Klass* primary_super_of_depth(juint i) const {
 205     assert(i < primary_super_limit(), "oob");
 206     Klass* super = _primary_supers[i];
 207     assert(super == NULL || super->super_depth() == i, "correct display");
 208     return super;
 209   }
 210 
 211   // Can this klass be a primary super?  False for interfaces and arrays of
 212   // interfaces.  False also for arrays or classes with long super chains.
 213   bool can_be_primary_super() const {
 214     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 215     return super_check_offset() != secondary_offset;
 216   }
 217   virtual bool can_be_primary_super_slow() const;
 218 
 219   // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
 220   juint super_depth() const {
 221     if (!can_be_primary_super()) {
 222       return primary_super_limit();
 223     } else {
 224       juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
 225       assert(d < primary_super_limit(), "oob");
 226       assert(_primary_supers[d] == this, "proper init");
 227       return d;
 228     }
 229   }
 230 
 231   // java mirror
 232   oop java_mirror() const;
 233   void set_java_mirror(Handle m);
 234 
 235   // Temporary mirror switch used by RedefineClasses
 236   // Both mirrors are on the ClassLoaderData::_handles list already so no
 237   // barriers are needed.
 238   void set_java_mirror_handle(OopHandle mirror) { _java_mirror = mirror; }
 239   OopHandle java_mirror_handle() const          { return _java_mirror; }
 240 
 241   // modifier flags
 242   jint modifier_flags() const          { return _modifier_flags; }
 243   void set_modifier_flags(jint flags)  { _modifier_flags = flags; }
 244 
 245   // size helper
 246   int layout_helper() const            { return _layout_helper; }
 247   void set_layout_helper(int lh)       { _layout_helper = lh; }
 248 
 249   // Note: for instances layout_helper() may include padding.
 250   // Use InstanceKlass::contains_field_offset to classify field offsets.
 251 
 252   // sub/superklass links
 253   Klass* subklass() const              { return _subklass; }
 254   Klass* next_sibling() const          { return _next_sibling; }
 255   InstanceKlass* superklass() const;
 256   void append_to_sibling_list();           // add newly created receiver to superklass' subklass list
 257 
 258   void set_next_link(Klass* k) { _next_link = k; }
 259   Klass* next_link() const { return _next_link; }   // The next klass defined by the class loader.
 260 
 261   // class loader data
 262   ClassLoaderData* class_loader_data() const               { return _class_loader_data; }
 263   void set_class_loader_data(ClassLoaderData* loader_data) {  _class_loader_data = loader_data; }
 264 
 265   int shared_classpath_index() const   {
 266     return _shared_class_path_index;
 267   };
 268 
 269   void set_shared_classpath_index(int index) {
 270     _shared_class_path_index = index;
 271   };
 272 
 273   // Obtain the module or package for this class
 274   virtual ModuleEntry* module() const = 0;
 275   virtual PackageEntry* package() const = 0;
 276 
 277  protected:                                // internal accessors
 278   void     set_subklass(Klass* s);
 279   void     set_next_sibling(Klass* s);
 280 
 281  public:
 282 
 283   // Compiler support
 284   static ByteSize super_offset()                 { return in_ByteSize(offset_of(Klass, _super)); }
 285   static ByteSize super_check_offset_offset()    { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
 286   static ByteSize primary_supers_offset()        { return in_ByteSize(offset_of(Klass, _primary_supers)); }
 287   static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
 288   static ByteSize secondary_supers_offset()      { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
 289   static ByteSize java_mirror_offset()           { return in_ByteSize(offset_of(Klass, _java_mirror)); }
 290   static ByteSize modifier_flags_offset()        { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
 291   static ByteSize layout_helper_offset()         { return in_ByteSize(offset_of(Klass, _layout_helper)); }
 292   static ByteSize access_flags_offset()          { return in_ByteSize(offset_of(Klass, _access_flags)); }
 293 
 294   // Unpacking layout_helper:
 295   enum {
 296     _lh_neutral_value           = 0,  // neutral non-array non-instance value
 297     _lh_instance_slow_path_bit  = 0x01,
 298     _lh_log2_element_size_shift = BitsPerByte*0,
 299     _lh_log2_element_size_mask  = BitsPerLong-1,
 300     _lh_element_type_shift      = BitsPerByte*1,
 301     _lh_element_type_mask       = right_n_bits(BitsPerByte),  // shifted mask
 302     _lh_header_size_shift       = BitsPerByte*2,
 303     _lh_header_size_mask        = right_n_bits(BitsPerByte),  // shifted mask
 304     _lh_array_tag_bits          = 3,
 305     _lh_array_tag_shift         = BitsPerInt - _lh_array_tag_bits
 306   };
 307 
 308   static const unsigned int _lh_array_tag_type_value = 0Xfffffffc;
 309   static const unsigned int _lh_array_tag_vt_value   = 0Xfffffffd;
 310   static const unsigned int _lh_array_tag_obj_value  = 0Xfffffffe;
 311 
 312   static int layout_helper_size_in_bytes(jint lh) {
 313     assert(lh > (jint)_lh_neutral_value, "must be instance");
 314     return (int) lh & ~_lh_instance_slow_path_bit;
 315   }
 316   static bool layout_helper_needs_slow_path(jint lh) {
 317     assert(lh > (jint)_lh_neutral_value, "must be instance");
 318     return (lh & _lh_instance_slow_path_bit) != 0;
 319   }
 320   static bool layout_helper_is_instance(jint lh) {
 321     return (jint)lh > (jint)_lh_neutral_value;
 322   }
 323   static bool layout_helper_is_array(jint lh) {
 324     return (jint)lh < (jint)_lh_neutral_value;
 325   }
 326   static bool layout_helper_is_typeArray(jint lh) {
 327     return (juint) _lh_array_tag_type_value == (juint)(lh >> _lh_array_tag_shift);
 328   }
 329   static bool layout_helper_is_objArray(jint lh) {
 330     return (juint)_lh_array_tag_obj_value == (juint)(lh >> _lh_array_tag_shift);
 331   }
 332   static bool layout_helper_is_valueArray(jint lh) {
 333     return (juint)_lh_array_tag_vt_value == (juint)(lh >> _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) || btvalue == T_VALUETYPE, "sanity");
 345     return (BasicType) btvalue;
 346   }
 347 
 348   // Want a pattern to quickly diff against layout header in register
 349   // find something less clever!
 350   static int layout_helper_boolean_diffbit() {
 351     jint zlh = array_layout_helper(T_BOOLEAN);
 352     jint blh = array_layout_helper(T_BYTE);
 353     assert(zlh != blh, "array layout helpers must differ");
 354     int diffbit = 1;
 355     while ((diffbit & (zlh ^ blh)) == 0 && (diffbit & zlh) == 0) {
 356       diffbit <<= 1;
 357       assert(diffbit != 0, "make sure T_BOOLEAN has a different bit than T_BYTE");
 358     }
 359     return diffbit;
 360   }
 361 
 362   static int layout_helper_log2_element_size(jint lh) {
 363     assert(lh < (jint)_lh_neutral_value, "must be array");
 364     int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
 365     assert(layout_helper_element_type(lh) == T_VALUETYPE || l2esz <= LogBytesPerLong,
 366            "sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh);
 367     return l2esz;
 368   }
 369   static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
 370     return (tag        << _lh_array_tag_shift)
 371       |    (hsize      << _lh_header_size_shift)
 372       |    ((int)etype << _lh_element_type_shift)
 373       |    (log2_esize << _lh_log2_element_size_shift);
 374   }
 375   static jint instance_layout_helper(jint size, bool slow_path_flag) {
 376     return (size << LogBytesPerWord)
 377       |    (slow_path_flag ? _lh_instance_slow_path_bit : 0);
 378   }
 379   static int layout_helper_to_size_helper(jint lh) {
 380     assert(lh > (jint)_lh_neutral_value, "must be instance");
 381     // Note that the following expression discards _lh_instance_slow_path_bit.
 382     return lh >> LogBytesPerWord;
 383   }
 384   // Out-of-line version computes everything based on the etype:
 385   static jint array_layout_helper(BasicType etype);
 386 
 387   // What is the maximum number of primary superclasses any klass can have?
 388 #ifdef PRODUCT
 389   static juint primary_super_limit()         { return _primary_super_limit; }
 390 #else
 391   static juint primary_super_limit() {
 392     assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
 393     return FastSuperclassLimit;
 394   }
 395 #endif
 396 
 397   // vtables
 398   klassVtable vtable() const;
 399   int vtable_length() const { return _vtable_len; }
 400 
 401   // subclass check
 402   bool is_subclass_of(const Klass* k) const;
 403   // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
 404   bool is_subtype_of(Klass* k) const {
 405     juint    off = k->super_check_offset();
 406     Klass* sup = *(Klass**)( (address)this + off );
 407     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 408     if (sup == k) {
 409       return true;
 410     } else if (off != secondary_offset) {
 411       return false;
 412     } else {
 413       return search_secondary_supers(k);
 414     }
 415   }
 416 
 417   // Is an oop/narrowOop null or subtype of this Klass?
 418   template <typename T>
 419   bool is_instanceof_or_null(T element);
 420 
 421   bool search_secondary_supers(Klass* k) const;
 422 
 423   // Find LCA in class hierarchy
 424   Klass *LCA( Klass *k );
 425 
 426   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
 427   // if not, throw either an Error or an Exception.
 428   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
 429 
 430   // array copying
 431   virtual void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
 432 
 433   // tells if the class should be initialized
 434   virtual bool should_be_initialized() const    { return false; }
 435   // initializes the klass
 436   virtual void initialize(TRAPS);
 437   // lookup operation for MethodLookupCache
 438   friend class MethodLookupCache;
 439   virtual Klass* find_field(Symbol* name, Symbol* signature, fieldDescriptor* fd) const;
 440   virtual Method* uncached_lookup_method(const Symbol* name, const Symbol* signature, OverpassLookupMode overpass_mode) const;
 441  public:
 442   Method* lookup_method(const Symbol* name, const Symbol* signature) const {
 443     return uncached_lookup_method(name, signature, find_overpass);
 444   }
 445 
 446   // array class with specific rank
 447   Klass* array_klass(int rank, TRAPS)         {  return array_klass_impl(false, rank, THREAD); }
 448 
 449   // array class with this klass as element type
 450   Klass* array_klass(TRAPS)                   {  return array_klass_impl(false, THREAD); }
 451 
 452   // These will return NULL instead of allocating on the heap:
 453   // NB: these can block for a mutex, like other functions with TRAPS arg.
 454   Klass* array_klass_or_null(int rank);
 455   Klass* array_klass_or_null();
 456 
 457   virtual oop protection_domain() const = 0;
 458 
 459   oop class_loader() const;
 460 
 461   virtual oop klass_holder() const      { return class_loader(); }
 462 
 463  protected:
 464   virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
 465   virtual Klass* array_klass_impl(bool or_null, TRAPS);
 466 
 467   void set_vtable_length(int len) { _vtable_len= len; }
 468 
 469   vtableEntry* start_of_vtable() const;
 470  public:
 471   Method* method_at_vtable(int index);
 472 
 473   static ByteSize vtable_start_offset();
 474   static ByteSize vtable_length_offset() {
 475     return byte_offset_of(Klass, _vtable_len);
 476   }
 477 
 478   // CDS support - remove and restore oops from metadata. Oops are not shared.
 479   virtual void remove_unshareable_info();
 480   virtual void remove_java_mirror();
 481   virtual void restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS);
 482 
 483  protected:
 484   // computes the subtype relationship
 485   virtual bool compute_is_subtype_of(Klass* k);
 486  public:
 487   // subclass accessor (here for convenience; undefined for non-klass objects)
 488   virtual bool is_leaf_class() const { fatal("not a class"); return false; }
 489  public:
 490   // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
 491   // These functions describe behavior for the oop not the KLASS.
 492 
 493   // actual oop size of obj in memory
 494   virtual int oop_size(oop obj) const = 0;
 495 
 496   // Size of klass in word size.
 497   virtual int size() const = 0;
 498 #if INCLUDE_SERVICES
 499   virtual void collect_statistics(KlassSizeStats *sz) const;
 500 #endif
 501 
 502   // Returns the Java name for a class (Resource allocated)
 503   // For arrays, this returns the name of the element with a leading '['.
 504   // For classes, this returns the name with the package separators
 505   //     turned into '.'s.
 506   const char* external_name() const;
 507   // Returns the name for a class (Resource allocated) as the class
 508   // would appear in a signature.
 509   // For arrays, this returns the name of the element with a leading '['.
 510   // For classes, this returns the name with a leading 'L' and a trailing ';'
 511   //     and the package separators as '/'.
 512   virtual const char* signature_name() const;
 513 
 514   const char* class_loader_and_module_name() const;
 515 
 516   // type testing operations
 517 #ifdef ASSERT
 518  protected:
 519   virtual bool is_instance_klass_slow()     const { return false; }
 520   virtual bool is_array_klass_slow()        const { return false; }
 521   virtual bool is_objArray_klass_slow()     const { return false; }
 522   virtual bool is_typeArray_klass_slow()    const { return false; }
 523   virtual bool is_valueArray_klass_slow()   const { return false; }
 524 #endif // ASSERT
 525   // current implementation uses this method even in non debug builds
 526   virtual bool is_value_slow()          const { return false; }
 527  public:
 528 
 529   // Fast non-virtual versions
 530   #ifndef ASSERT
 531   #define assert_same_query(xval, xcheck) xval
 532   #else
 533  private:
 534   static bool assert_same_query(bool xval, bool xslow) {
 535     assert(xval == xslow, "slow and fast queries agree");
 536     return xval;
 537   }
 538  public:
 539   #endif
 540   inline  bool is_instance_klass()            const { return assert_same_query(
 541                                                       layout_helper_is_instance(layout_helper()),
 542                                                       is_instance_klass_slow()); }
 543   inline  bool is_array_klass()               const { return assert_same_query(
 544                                                     layout_helper_is_array(layout_helper()),
 545                                                     is_array_klass_slow()); }
 546   inline  bool is_objArray_klass()            const { return assert_same_query(
 547                                                     layout_helper_is_objArray(layout_helper()),
 548                                                     is_objArray_klass_slow()); }
 549   inline  bool is_typeArray_klass()           const { return assert_same_query(
 550                                                     layout_helper_is_typeArray(layout_helper()),
 551                                                     is_typeArray_klass_slow()); }
 552   inline  bool is_value()                     const { return is_value_slow(); } //temporary hack
 553   inline  bool is_valueArray_klass()          const { return assert_same_query(
 554                                                     layout_helper_is_valueArray(layout_helper()),
 555                                                     is_valueArray_klass_slow()); }
 556 
 557   #undef assert_same_query
 558 
 559   // Access flags
 560   AccessFlags access_flags() const         { return _access_flags;  }
 561   void set_access_flags(AccessFlags flags) { _access_flags = flags; }
 562 
 563   bool is_public() const                { return _access_flags.is_public(); }
 564   bool is_final() const                 { return _access_flags.is_final(); }
 565   bool is_interface() const             { return _access_flags.is_interface(); }
 566   bool is_abstract() const              { return _access_flags.is_abstract(); }
 567   bool is_super() const                 { return _access_flags.is_super(); }
 568   bool is_synthetic() const             { return _access_flags.is_synthetic(); }
 569   void set_is_synthetic()               { _access_flags.set_is_synthetic(); }
 570   bool has_finalizer() const            { return _access_flags.has_finalizer(); }
 571   bool has_final_method() const         { return _access_flags.has_final_method(); }
 572   void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
 573   void set_has_final_method()           { _access_flags.set_has_final_method(); }
 574   bool has_vanilla_constructor() const  { return _access_flags.has_vanilla_constructor(); }
 575   void set_has_vanilla_constructor()    { _access_flags.set_has_vanilla_constructor(); }
 576   bool has_miranda_methods () const     { return access_flags().has_miranda_methods(); }
 577   void set_has_miranda_methods()        { _access_flags.set_has_miranda_methods(); }
 578   bool is_shared() const                { return access_flags().is_shared_class(); } // shadows MetaspaceObj::is_shared)()
 579   void set_is_shared()                  { _access_flags.set_is_shared_class(); }
 580 
 581   bool is_cloneable() const;
 582   void set_is_cloneable();
 583 
 584   // Biased locking support
 585   // Note: the prototype header is always set up to be at least the
 586   // prototype markOop. If biased locking is enabled it may further be
 587   // biasable and have an epoch.
 588   markOop prototype_header() const      { return _prototype_header; }
 589   // NOTE: once instances of this klass are floating around in the
 590   // system, this header must only be updated at a safepoint.
 591   // NOTE 2: currently we only ever set the prototype header to the
 592   // biasable prototype for instanceKlasses. There is no technical
 593   // reason why it could not be done for arrayKlasses aside from
 594   // wanting to reduce the initial scope of this optimization. There
 595   // are potential problems in setting the bias pattern for
 596   // JVM-internal oops.
 597   inline void set_prototype_header(markOop header);
 598   static ByteSize prototype_header_offset() { return in_ByteSize(offset_of(Klass, _prototype_header)); }
 599 
 600   int  biased_lock_revocation_count() const { return (int) _biased_lock_revocation_count; }
 601   // Atomically increments biased_lock_revocation_count and returns updated value
 602   int atomic_incr_biased_lock_revocation_count();
 603   void set_biased_lock_revocation_count(int val) { _biased_lock_revocation_count = (jint) val; }
 604   jlong last_biased_lock_bulk_revocation_time() { return _last_biased_lock_bulk_revocation_time; }
 605   void  set_last_biased_lock_bulk_revocation_time(jlong cur_time) { _last_biased_lock_bulk_revocation_time = cur_time; }
 606 
 607   TRACE_DEFINE_TRACE_ID_METHODS;
 608 
 609   virtual void metaspace_pointers_do(MetaspaceClosure* iter);
 610   virtual MetaspaceObj::Type type() const { return ClassType; }
 611 
 612   // Iff the class loader (or mirror for anonymous classes) is alive the
 613   // Klass is considered alive.
 614   // The is_alive closure passed in depends on the Garbage Collector used.
 615   bool is_loader_alive(BoolObjectClosure* is_alive);
 616 
 617   static void clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses = true);
 618   static void clean_subklass_tree(BoolObjectClosure* is_alive) {
 619     clean_weak_klass_links(is_alive, false /* clean_alive_klasses */);
 620   }
 621 
 622   // GC specific object visitors
 623   //
 624 #if INCLUDE_ALL_GCS
 625   // Parallel Scavenge
 626   virtual void oop_ps_push_contents(  oop obj, PSPromotionManager* pm)   = 0;
 627   // Parallel Compact
 628   virtual void oop_pc_follow_contents(oop obj, ParCompactionManager* cm) = 0;
 629   virtual void oop_pc_update_pointers(oop obj, ParCompactionManager* cm) = 0;
 630 #endif
 631 
 632   // Iterators specialized to particular subtypes
 633   // of ExtendedOopClosure, to avoid closure virtual calls.
 634 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                           \
 635   virtual void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) = 0;                        \
 636   /* Iterates "closure" over all the oops in "obj" (of type "this") within "mr". */                     \
 637   virtual void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) = 0;
 638 
 639   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
 640   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
 641 
 642 #if INCLUDE_ALL_GCS
 643 #define Klass_OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix)                     \
 644   virtual void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) = 0;
 645 
 646   ALL_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
 647   ALL_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL_BACKWARDS)
 648 #endif // INCLUDE_ALL_GCS
 649 
 650   virtual void array_klasses_do(void f(Klass* k)) {}
 651 
 652   // Return self, except for abstract classes with exactly 1
 653   // implementor.  Then return the 1 concrete implementation.
 654   Klass *up_cast_abstract();
 655 
 656   // klass name
 657   Symbol* name() const                   { return _name; }
 658   void set_name(Symbol* n);
 659 
 660  public:
 661   // jvm support
 662   virtual jint compute_modifier_flags(TRAPS) const;
 663 
 664   // JVMTI support
 665   virtual jint jvmti_class_status() const;
 666 
 667   // Printing
 668   virtual void print_on(outputStream* st) const;
 669 
 670   virtual void oop_print_value_on(oop obj, outputStream* st);
 671   virtual void oop_print_on      (oop obj, outputStream* st);
 672 
 673   virtual const char* internal_name() const = 0;
 674 
 675   // Verification
 676   virtual void verify_on(outputStream* st);
 677   void verify() { verify_on(tty); }
 678 
 679 #ifndef PRODUCT
 680   bool verify_vtable_index(int index);
 681   bool verify_itable_index(int index);
 682 #endif
 683 
 684   virtual void oop_verify_on(oop obj, outputStream* st);
 685 
 686   static bool is_null(narrowKlass obj);
 687   static bool is_null(Klass* obj);
 688 
 689   // klass encoding for klass pointer in objects.
 690   static narrowKlass encode_klass_not_null(Klass* v);
 691   static narrowKlass encode_klass(Klass* v);
 692 
 693   static Klass* decode_klass_not_null(narrowKlass v);
 694   static Klass* decode_klass(narrowKlass v);
 695 
 696   static bool decode_ptr_is_value_type(narrowKlass v);
 697   static bool ptr_is_value_type(Klass* v);
 698 };
 699 
 700 // Helper to convert the oop iterate macro suffixes into bool values that can be used by template functions.
 701 #define nvs_nv_to_bool true
 702 #define nvs_v_to_bool  false
 703 #define nvs_to_bool(nv_suffix) nvs##nv_suffix##_to_bool
 704 
 705 // Oop iteration macros for declarations.
 706 // Used to generate declarations in the *Klass header files.
 707 
 708 #define OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                                    \
 709   void oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure);                        \
 710   void oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr);
 711 
 712 #if INCLUDE_ALL_GCS
 713 #define OOP_OOP_ITERATE_DECL_BACKWARDS(OopClosureType, nv_suffix)               \
 714   void oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure);
 715 #endif // INCLUDE_ALL_GCS
 716 
 717 
 718 // Oop iteration macros for definitions.
 719 // Used to generate definitions in the *Klass.inline.hpp files.
 720 
 721 #define OOP_OOP_ITERATE_DEFN(KlassType, OopClosureType, nv_suffix)              \
 722 void KlassType::oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) {  \
 723   oop_oop_iterate<nvs_to_bool(nv_suffix)>(obj, closure);                        \
 724 }
 725 
 726 #if INCLUDE_ALL_GCS
 727 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)              \
 728 void KlassType::oop_oop_iterate_backwards##nv_suffix(oop obj, OopClosureType* closure) {  \
 729   oop_oop_iterate_reverse<nvs_to_bool(nv_suffix)>(obj, closure);                          \
 730 }
 731 #else
 732 #define OOP_OOP_ITERATE_DEFN_BACKWARDS(KlassType, OopClosureType, nv_suffix)
 733 #endif
 734 
 735 #define OOP_OOP_ITERATE_DEFN_BOUNDED(KlassType, OopClosureType, nv_suffix)                            \
 736 void KlassType::oop_oop_iterate_bounded##nv_suffix(oop obj, OopClosureType* closure, MemRegion mr) {  \
 737   oop_oop_iterate_bounded<nvs_to_bool(nv_suffix)>(obj, closure, mr);                                  \
 738 }
 739 
 740 #endif // SHARE_VM_OOPS_KLASS_HPP