1 /*
   2  * Copyright (c) 1997, 2013, 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 "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 "runtime/orderAccess.hpp"
  36 #include "trace/traceMacros.hpp"
  37 #include "utilities/accessFlags.hpp"
  38 #include "utilities/macros.hpp"
  39 #if INCLUDE_ALL_GCS
  40 #include "gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp"
  41 #include "gc_implementation/g1/g1OopClosures.hpp"
  42 #include "gc_implementation/parNew/parOopClosures.hpp"
  43 #endif // INCLUDE_ALL_GCS
  44 
  45 //
  46 // A Klass provides:
  47 //  1: language level class object (method dictionary etc.)
  48 //  2: provide vm dispatch behavior for the object
  49 // Both functions are combined into one C++ class.
  50 
  51 // One reason for the oop/klass dichotomy in the implementation is
  52 // that we don't want a C++ vtbl pointer in every object.  Thus,
  53 // normal oops don't have any virtual functions.  Instead, they
  54 // forward all "virtual" functions to their klass, which does have
  55 // a vtbl and does the C++ dispatch depending on the object's
  56 // actual type.  (See oop.inline.hpp for some of the forwarding code.)
  57 // ALL FUNCTIONS IMPLEMENTING THIS DISPATCH ARE PREFIXED WITH "oop_"!
  58 
  59 //  Klass layout:
  60 //    [C++ vtbl ptr  ] (contained in Metadata)
  61 //    [layout_helper ]
  62 //    [super_check_offset   ] for fast subtype checks
  63 //    [name          ]
  64 //    [secondary_super_cache] for fast subtype checks
  65 //    [secondary_supers     ] array of 2ndary supertypes
  66 //    [primary_supers 0]
  67 //    [primary_supers 1]
  68 //    [primary_supers 2]
  69 //    ...
  70 //    [primary_supers 7]
  71 //    [java_mirror   ]
  72 //    [super         ]
  73 //    [subklass      ] first subclass
  74 //    [next_sibling  ] link to chain additional subklasses
  75 //    [next_link     ]
  76 //    [class_loader_data]
  77 //    [modifier_flags]
  78 //    [access_flags  ]
  79 //    [last_biased_lock_bulk_revocation_time] (64 bits)
  80 //    [prototype_header]
  81 //    [biased_lock_revocation_count]
  82 //    [_modified_oops]
  83 //    [_accumulated_modified_oops]
  84 //    [trace_id]
  85 
  86 
  87 // Forward declarations.
  88 template <class T> class Array;
  89 template <class T> class GrowableArray;
  90 class ClassLoaderData;
  91 class klassVtable;
  92 class ParCompactionManager;
  93 class KlassSizeStats;
  94 
  95 class Klass : public Metadata {
  96   friend class VMStructs;
  97  protected:
  98   // note: put frequently-used fields together at start of klass structure
  99   // for better cache behavior (may not make much of a difference but sure won't hurt)
 100   enum { _primary_super_limit = 8 };
 101 
 102   // The "layout helper" is a combined descriptor of object layout.
 103   // For klasses which are neither instance nor array, the value is zero.
 104   //
 105   // For instances, layout helper is a positive number, the instance size.
 106   // This size is already passed through align_object_size and scaled to bytes.
 107   // The low order bit is set if instances of this class cannot be
 108   // allocated using the fastpath.
 109   //
 110   // For arrays, layout helper is a negative number, containing four
 111   // distinct bytes, as follows:
 112   //    MSB:[tag, hsz, ebt, log2(esz)]:LSB
 113   // where:
 114   //    tag is 0x80 if the elements are oops, 0xC0 if non-oops
 115   //    hsz is array header size in bytes (i.e., offset of first element)
 116   //    ebt is the BasicType of the elements
 117   //    esz is the element size in bytes
 118   // This packed word is arranged so as to be quickly unpacked by the
 119   // various fast paths that use the various subfields.
 120   //
 121   // The esz bits can be used directly by a SLL instruction, without masking.
 122   //
 123   // Note that the array-kind tag looks like 0x00 for instance klasses,
 124   // since their length in bytes is always less than 24Mb.
 125   //
 126   // Final note:  This comes first, immediately after C++ vtable,
 127   // because it is frequently queried.
 128   jint        _layout_helper;
 129 
 130   // The fields _super_check_offset, _secondary_super_cache, _secondary_supers
 131   // and _primary_supers all help make fast subtype checks.  See big discussion
 132   // in doc/server_compiler/checktype.txt
 133   //
 134   // Where to look to observe a supertype (it is &_secondary_super_cache for
 135   // secondary supers, else is &_primary_supers[depth()].
 136   juint       _super_check_offset;
 137 
 138   // Class name.  Instance classes: java/lang/String, etc.  Array classes: [I,
 139   // [Ljava/lang/String;, etc.  Set to zero for all other kinds of classes.
 140   Symbol*     _name;
 141 
 142   // Cache of last observed secondary supertype
 143   Klass*      _secondary_super_cache;
 144   // Array of all secondary supertypes
 145   Array<Klass*>* _secondary_supers;
 146   // Ordered list of all primary supertypes
 147   Klass*      _primary_supers[_primary_super_limit];
 148   // java/lang/Class instance mirroring this class
 149   oop       _java_mirror;
 150   // Superclass
 151   Klass*      _super;
 152   // First subclass (NULL if none); _subklass->next_sibling() is next one
 153   Klass*      _subklass;
 154   // Sibling link (or NULL); links all subklasses of a klass
 155   Klass*      _next_sibling;
 156 
 157   // All klasses loaded by a class loader are chained through these links
 158   Klass*      _next_link;
 159 
 160   // The VM's representation of the ClassLoader used to load this class.
 161   // Provide access the corresponding instance java.lang.ClassLoader.
 162   ClassLoaderData* _class_loader_data;
 163 
 164   jint        _modifier_flags;  // Processed access flags, for use by Class.getModifiers.
 165   AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.
 166 
 167   // Biased locking implementation and statistics
 168   // (the 64-bit chunk goes first, to avoid some fragmentation)
 169   jlong    _last_biased_lock_bulk_revocation_time;
 170   markOop  _prototype_header;   // Used when biased locking is both enabled and disabled for this type
 171   jint     _biased_lock_revocation_count;
 172 
 173   TRACE_DEFINE_KLASS_TRACE_ID;
 174 
 175   // Remembered sets support for the oops in the klasses.
 176   jbyte _modified_oops;             // Card Table Equivalent (YC/CMS support)
 177   jbyte _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
 178 
 179   // Constructor
 180   Klass();
 181 
 182   void* operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS);
 183 
 184  public:
 185   bool is_klass() const volatile { return true; }
 186 
 187   // super
 188   Klass* super() const               { return _super; }
 189   void set_super(Klass* k)           { _super = k; }
 190 
 191   // initializes _super link, _primary_supers & _secondary_supers arrays
 192   void initialize_supers(Klass* k, TRAPS);
 193   void initialize_supers_impl1(Klass* k);
 194   void initialize_supers_impl2(Klass* k);
 195 
 196   // klass-specific helper for initializing _secondary_supers
 197   virtual GrowableArray<Klass*>* compute_secondary_supers(int num_extra_slots);
 198 
 199   // java_super is the Java-level super type as specified by Class.getSuperClass.
 200   virtual Klass* java_super() const  { return NULL; }
 201 
 202   juint    super_check_offset() const  { return _super_check_offset; }
 203   void set_super_check_offset(juint o) { _super_check_offset = o; }
 204 
 205   Klass* secondary_super_cache() const     { return _secondary_super_cache; }
 206   void set_secondary_super_cache(Klass* k) { _secondary_super_cache = k; }
 207 
 208   Array<Klass*>* secondary_supers() const { return _secondary_supers; }
 209   void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
 210 
 211   // Return the element of the _super chain of the given depth.
 212   // If there is no such element, return either NULL or this.
 213   Klass* primary_super_of_depth(juint i) const {
 214     assert(i < primary_super_limit(), "oob");
 215     Klass* super = _primary_supers[i];
 216     assert(super == NULL || super->super_depth() == i, "correct display");
 217     return super;
 218   }
 219 
 220   // Can this klass be a primary super?  False for interfaces and arrays of
 221   // interfaces.  False also for arrays or classes with long super chains.
 222   bool can_be_primary_super() const {
 223     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 224     return super_check_offset() != secondary_offset;
 225   }
 226   virtual bool can_be_primary_super_slow() const;
 227 
 228   // Returns number of primary supers; may be a number in the inclusive range [0, primary_super_limit].
 229   juint super_depth() const {
 230     if (!can_be_primary_super()) {
 231       return primary_super_limit();
 232     } else {
 233       juint d = (super_check_offset() - in_bytes(primary_supers_offset())) / sizeof(Klass*);
 234       assert(d < primary_super_limit(), "oob");
 235       assert(_primary_supers[d] == this, "proper init");
 236       return d;
 237     }
 238   }
 239 
 240   // store an oop into a field of a Klass
 241   void klass_oop_store(oop* p, oop v);
 242   void klass_oop_store(volatile oop* p, oop v);
 243 
 244   // java mirror
 245   oop java_mirror() const              { return _java_mirror; }
 246   void set_java_mirror(oop m) { klass_oop_store(&_java_mirror, m); }
 247 
 248   // modifier flags
 249   jint modifier_flags() const          { return _modifier_flags; }
 250   void set_modifier_flags(jint flags)  { _modifier_flags = flags; }
 251 
 252   // size helper
 253   int layout_helper() const            { return _layout_helper; }
 254   void set_layout_helper(int lh)       { _layout_helper = lh; }
 255 
 256   // Note: for instances layout_helper() may include padding.
 257   // Use InstanceKlass::contains_field_offset to classify field offsets.
 258 
 259   // sub/superklass links
 260   InstanceKlass* superklass() const;
 261   Klass* subklass() const;
 262   Klass* next_sibling() const;
 263   void append_to_sibling_list();           // add newly created receiver to superklass' subklass list
 264 
 265   void set_next_link(Klass* k) { _next_link = k; }
 266   Klass* next_link() const { return _next_link; }   // The next klass defined by the class loader.
 267 
 268   // class loader data
 269   ClassLoaderData* class_loader_data() const               { return _class_loader_data; }
 270   void set_class_loader_data(ClassLoaderData* loader_data) {  _class_loader_data = loader_data; }
 271 
 272   // The Klasses are not placed in the Heap, so the Card Table or
 273   // the Mod Union Table can't be used to mark when klasses have modified oops.
 274   // The CT and MUT bits saves this information for the individual Klasses.
 275   void record_modified_oops()            { _modified_oops = 1; }
 276   void clear_modified_oops()             { _modified_oops = 0; }
 277   bool has_modified_oops()               { return _modified_oops == 1; }
 278 
 279   void accumulate_modified_oops()        { if (has_modified_oops()) _accumulated_modified_oops = 1; }
 280   void clear_accumulated_modified_oops() { _accumulated_modified_oops = 0; }
 281   bool has_accumulated_modified_oops()   { return _accumulated_modified_oops == 1; }
 282 
 283  protected:                                // internal accessors
 284   Klass* subklass_oop() const            { return _subklass; }
 285   Klass* next_sibling_oop() const        { return _next_sibling; }
 286   void     set_subklass(Klass* s);
 287   void     set_next_sibling(Klass* s);
 288 
 289  public:
 290 
 291   // Compiler support
 292   static ByteSize super_offset()                 { return in_ByteSize(offset_of(Klass, _super)); }
 293   static ByteSize super_check_offset_offset()    { return in_ByteSize(offset_of(Klass, _super_check_offset)); }
 294   static ByteSize primary_supers_offset()        { return in_ByteSize(offset_of(Klass, _primary_supers)); }
 295   static ByteSize secondary_super_cache_offset() { return in_ByteSize(offset_of(Klass, _secondary_super_cache)); }
 296   static ByteSize secondary_supers_offset()      { return in_ByteSize(offset_of(Klass, _secondary_supers)); }
 297   static ByteSize java_mirror_offset()           { return in_ByteSize(offset_of(Klass, _java_mirror)); }
 298   static ByteSize modifier_flags_offset()        { return in_ByteSize(offset_of(Klass, _modifier_flags)); }
 299   static ByteSize layout_helper_offset()         { return in_ByteSize(offset_of(Klass, _layout_helper)); }
 300   static ByteSize access_flags_offset()          { return in_ByteSize(offset_of(Klass, _access_flags)); }
 301 
 302   // Unpacking layout_helper:
 303   enum {
 304     _lh_neutral_value           = 0,  // neutral non-array non-instance value
 305     _lh_instance_slow_path_bit  = 0x01,
 306     _lh_log2_element_size_shift = BitsPerByte*0,
 307     _lh_log2_element_size_mask  = BitsPerLong-1,
 308     _lh_element_type_shift      = BitsPerByte*1,
 309     _lh_element_type_mask       = right_n_bits(BitsPerByte),  // shifted mask
 310     _lh_header_size_shift       = BitsPerByte*2,
 311     _lh_header_size_mask        = right_n_bits(BitsPerByte),  // shifted mask
 312     _lh_array_tag_bits          = 2,
 313     _lh_array_tag_shift         = BitsPerInt - _lh_array_tag_bits,
 314     _lh_array_tag_type_value    = ~0x00,  // 0xC0000000 >> 30
 315     _lh_array_tag_obj_value     = ~0x01   // 0x80000000 >> 30
 316   };
 317 
 318   static int layout_helper_size_in_bytes(jint lh) {
 319     assert(lh > (jint)_lh_neutral_value, "must be instance");
 320     return (int) lh & ~_lh_instance_slow_path_bit;
 321   }
 322   static bool layout_helper_needs_slow_path(jint lh) {
 323     assert(lh > (jint)_lh_neutral_value, "must be instance");
 324     return (lh & _lh_instance_slow_path_bit) != 0;
 325   }
 326   static bool layout_helper_is_instance(jint lh) {
 327     return (jint)lh > (jint)_lh_neutral_value;
 328   }
 329   static bool layout_helper_is_array(jint lh) {
 330     return (jint)lh < (jint)_lh_neutral_value;
 331   }
 332   static bool layout_helper_is_typeArray(jint lh) {
 333     // _lh_array_tag_type_value == (lh >> _lh_array_tag_shift);
 334     return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
 335   }
 336   static bool layout_helper_is_objArray(jint lh) {
 337     // _lh_array_tag_obj_value == (lh >> _lh_array_tag_shift);
 338     return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
 339   }
 340   static int layout_helper_header_size(jint lh) {
 341     assert(lh < (jint)_lh_neutral_value, "must be array");
 342     int hsize = (lh >> _lh_header_size_shift) & _lh_header_size_mask;
 343     assert(hsize > 0 && hsize < (int)sizeof(oopDesc)*3, "sanity");
 344     return hsize;
 345   }
 346   static BasicType layout_helper_element_type(jint lh) {
 347     assert(lh < (jint)_lh_neutral_value, "must be array");
 348     int btvalue = (lh >> _lh_element_type_shift) & _lh_element_type_mask;
 349     assert(btvalue >= T_BOOLEAN && btvalue <= T_OBJECT, "sanity");
 350     return (BasicType) btvalue;
 351   }
 352   static int layout_helper_log2_element_size(jint lh) {
 353     assert(lh < (jint)_lh_neutral_value, "must be array");
 354     int l2esz = (lh >> _lh_log2_element_size_shift) & _lh_log2_element_size_mask;
 355     assert(l2esz <= LogBitsPerLong,
 356         err_msg("sanity. l2esz: 0x%x for lh: 0x%x", (uint)l2esz, (uint)lh));
 357     return l2esz;
 358   }
 359   static jint array_layout_helper(jint tag, int hsize, BasicType etype, int log2_esize) {
 360     return (tag        << _lh_array_tag_shift)
 361       |    (hsize      << _lh_header_size_shift)
 362       |    ((int)etype << _lh_element_type_shift)
 363       |    (log2_esize << _lh_log2_element_size_shift);
 364   }
 365   static jint instance_layout_helper(jint size, bool slow_path_flag) {
 366     return (size << LogHeapWordSize)
 367       |    (slow_path_flag ? _lh_instance_slow_path_bit : 0);
 368   }
 369   static int layout_helper_to_size_helper(jint lh) {
 370     assert(lh > (jint)_lh_neutral_value, "must be instance");
 371     // Note that the following expression discards _lh_instance_slow_path_bit.
 372     return lh >> LogHeapWordSize;
 373   }
 374   // Out-of-line version computes everything based on the etype:
 375   static jint array_layout_helper(BasicType etype);
 376 
 377   // What is the maximum number of primary superclasses any klass can have?
 378 #ifdef PRODUCT
 379   static juint primary_super_limit()         { return _primary_super_limit; }
 380 #else
 381   static juint primary_super_limit() {
 382     assert(FastSuperclassLimit <= _primary_super_limit, "parameter oob");
 383     return FastSuperclassLimit;
 384   }
 385 #endif
 386 
 387   // vtables
 388   virtual klassVtable* vtable() const        { return NULL; }
 389   virtual int vtable_length() const          { return 0; }
 390 
 391   // subclass check
 392   bool is_subclass_of(const Klass* k) const;
 393   // subtype check: true if is_subclass_of, or if k is interface and receiver implements it
 394   bool is_subtype_of(Klass* k) const {
 395     juint    off = k->super_check_offset();
 396     Klass* sup = *(Klass**)( (address)this + off );
 397     const juint secondary_offset = in_bytes(secondary_super_cache_offset());
 398     if (sup == k) {
 399       return true;
 400     } else if (off != secondary_offset) {
 401       return false;
 402     } else {
 403       return search_secondary_supers(k);
 404     }
 405   }
 406   bool search_secondary_supers(Klass* k) const;
 407 
 408   // Find LCA in class hierarchy
 409   Klass *LCA( Klass *k );
 410 
 411   // Check whether reflection/jni/jvm code is allowed to instantiate this class;
 412   // if not, throw either an Error or an Exception.
 413   virtual void check_valid_for_instantiation(bool throwError, TRAPS);
 414 
 415   // array copying
 416   virtual void  copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS);
 417 
 418   // tells if the class should be initialized
 419   virtual bool should_be_initialized() const    { return false; }
 420   // initializes the klass
 421   virtual void initialize(TRAPS);
 422   // lookup operation for MethodLookupCache
 423   friend class MethodLookupCache;
 424   virtual Method* uncached_lookup_method(Symbol* name, Symbol* signature) const;
 425  public:
 426   Method* lookup_method(Symbol* name, Symbol* signature) const {
 427     return uncached_lookup_method(name, signature);
 428   }
 429 
 430   // array class with specific rank
 431   Klass* array_klass(int rank, TRAPS)         {  return array_klass_impl(false, rank, THREAD); }
 432 
 433   // array class with this klass as element type
 434   Klass* array_klass(TRAPS)                   {  return array_klass_impl(false, THREAD); }
 435 
 436   // These will return NULL instead of allocating on the heap:
 437   // NB: these can block for a mutex, like other functions with TRAPS arg.
 438   Klass* array_klass_or_null(int rank);
 439   Klass* array_klass_or_null();
 440 
 441   virtual oop protection_domain() const = 0;
 442 
 443   oop class_loader() const;
 444 
 445   virtual oop klass_holder() const      { return class_loader(); }
 446 
 447  protected:
 448   virtual Klass* array_klass_impl(bool or_null, int rank, TRAPS);
 449   virtual Klass* array_klass_impl(bool or_null, TRAPS);
 450 
 451  public:
 452   // CDS support - remove and restore oops from metadata. Oops are not shared.
 453   virtual void remove_unshareable_info();
 454   virtual void restore_unshareable_info(TRAPS);
 455 
 456  protected:
 457   // computes the subtype relationship
 458   virtual bool compute_is_subtype_of(Klass* k);
 459  public:
 460   // subclass accessor (here for convenience; undefined for non-klass objects)
 461   virtual bool is_leaf_class() const { fatal("not a class"); return false; }
 462  public:
 463   // ALL FUNCTIONS BELOW THIS POINT ARE DISPATCHED FROM AN OOP
 464   // These functions describe behavior for the oop not the KLASS.
 465 
 466   // actual oop size of obj in memory
 467   virtual int oop_size(oop obj) const = 0;
 468 
 469   // Size of klass in word size.
 470   virtual int size() const = 0;
 471 #if INCLUDE_SERVICES
 472   virtual void collect_statistics(KlassSizeStats *sz) const;
 473 #endif
 474 
 475   // Returns the Java name for a class (Resource allocated)
 476   // For arrays, this returns the name of the element with a leading '['.
 477   // For classes, this returns the name with the package separators
 478   //     turned into '.'s.
 479   const char* external_name() const;
 480   // Returns the name for a class (Resource allocated) as the class
 481   // would appear in a signature.
 482   // For arrays, this returns the name of the element with a leading '['.
 483   // For classes, this returns the name with a leading 'L' and a trailing ';'
 484   //     and the package separators as '/'.
 485   virtual const char* signature_name() const;
 486 
 487   // garbage collection support
 488   virtual void oop_follow_contents(oop obj) = 0;
 489   virtual int  oop_adjust_pointers(oop obj) = 0;
 490 
 491   // Parallel Scavenge and Parallel Old
 492   PARALLEL_GC_DECLS_PV
 493 
 494   // type testing operations
 495  protected:
 496   virtual bool oop_is_instance_slow()       const { return false; }
 497   virtual bool oop_is_array_slow()          const { return false; }
 498   virtual bool oop_is_objArray_slow()       const { return false; }
 499   virtual bool oop_is_typeArray_slow()      const { return false; }
 500  public:
 501   virtual bool oop_is_instanceMirror()      const { return false; }
 502   virtual bool oop_is_instanceRef()         const { return false; }
 503 
 504   // Fast non-virtual versions
 505   #ifndef ASSERT
 506   #define assert_same_query(xval, xcheck) xval
 507   #else
 508  private:
 509   static bool assert_same_query(bool xval, bool xslow) {
 510     assert(xval == xslow, "slow and fast queries agree");
 511     return xval;
 512   }
 513  public:
 514   #endif
 515   inline  bool oop_is_instance()            const { return assert_same_query(
 516                                                     layout_helper_is_instance(layout_helper()),
 517                                                     oop_is_instance_slow()); }
 518   inline  bool oop_is_array()               const { return assert_same_query(
 519                                                     layout_helper_is_array(layout_helper()),
 520                                                     oop_is_array_slow()); }
 521   inline  bool oop_is_objArray()            const { return assert_same_query(
 522                                                     layout_helper_is_objArray(layout_helper()),
 523                                                     oop_is_objArray_slow()); }
 524   inline  bool oop_is_typeArray()           const { return assert_same_query(
 525                                                     layout_helper_is_typeArray(layout_helper()),
 526                                                     oop_is_typeArray_slow()); }
 527   #undef assert_same_query
 528 
 529   // Access flags
 530   AccessFlags access_flags() const         { return _access_flags;  }
 531   void set_access_flags(AccessFlags flags) { _access_flags = flags; }
 532 
 533   bool is_public() const                { return _access_flags.is_public(); }
 534   bool is_final() const                 { return _access_flags.is_final(); }
 535   bool is_interface() const             { return _access_flags.is_interface(); }
 536   bool is_abstract() const              { return _access_flags.is_abstract(); }
 537   bool is_super() const                 { return _access_flags.is_super(); }
 538   bool is_synthetic() const             { return _access_flags.is_synthetic(); }
 539   void set_is_synthetic()               { _access_flags.set_is_synthetic(); }
 540   bool has_finalizer() const            { return _access_flags.has_finalizer(); }
 541   bool has_final_method() const         { return _access_flags.has_final_method(); }
 542   void set_has_finalizer()              { _access_flags.set_has_finalizer(); }
 543   void set_has_final_method()           { _access_flags.set_has_final_method(); }
 544   bool is_cloneable() const             { return _access_flags.is_cloneable(); }
 545   void set_is_cloneable()               { _access_flags.set_is_cloneable(); }
 546   bool has_vanilla_constructor() const  { return _access_flags.has_vanilla_constructor(); }
 547   void set_has_vanilla_constructor()    { _access_flags.set_has_vanilla_constructor(); }
 548   bool has_miranda_methods () const     { return access_flags().has_miranda_methods(); }
 549   void set_has_miranda_methods()        { _access_flags.set_has_miranda_methods(); }
 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_KLASS_METHODS;
 575 
 576   // garbage collection support
 577   virtual 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);
 585 
 586   // Prefetch within oop iterators.  This is a macro because we
 587   // can't guarantee that the compiler will inline it.  In 64-bit
 588   // it generally doesn't.  Signature is
 589   //
 590   // static void prefetch_beyond(oop* const start,
 591   //                             oop* const end,
 592   //                             const intx foffset,
 593   //                             const Prefetch::style pstyle);
 594 #define prefetch_beyond(start, end, foffset, pstyle) {   \
 595     const intx foffset_ = (foffset);                     \
 596     const Prefetch::style pstyle_ = (pstyle);            \
 597     assert(foffset_ > 0, "prefetch beyond, not behind"); \
 598     if (pstyle_ != Prefetch::do_none) {                  \
 599       oop* ref = (start);                                \
 600       if (ref < (end)) {                                 \
 601         switch (pstyle_) {                               \
 602         case Prefetch::do_read:                          \
 603           Prefetch::read(*ref, foffset_);                \
 604           break;                                         \
 605         case Prefetch::do_write:                         \
 606           Prefetch::write(*ref, foffset_);               \
 607           break;                                         \
 608         default:                                         \
 609           ShouldNotReachHere();                          \
 610           break;                                         \
 611         }                                                \
 612       }                                                  \
 613     }                                                    \
 614   }
 615 
 616   // iterators
 617   virtual int oop_oop_iterate(oop obj, ExtendedOopClosure* blk) = 0;
 618   virtual int oop_oop_iterate_v(oop obj, ExtendedOopClosure* blk) {
 619     return oop_oop_iterate(obj, blk);
 620   }
 621 
 622 #if INCLUDE_ALL_GCS
 623   // In case we don't have a specialized backward scanner use forward
 624   // iteration.
 625   virtual int oop_oop_iterate_backwards_v(oop obj, ExtendedOopClosure* blk) {
 626     return oop_oop_iterate_v(obj, blk);
 627   }
 628 #endif // INCLUDE_ALL_GCS
 629 
 630   // Iterates "blk" over all the oops in "obj" (of type "this") within "mr".
 631   // (I don't see why the _m should be required, but without it the Solaris
 632   // C++ gives warning messages about overridings of the "oop_oop_iterate"
 633   // defined above "hiding" this virtual function.  (DLD, 6/20/00)) */
 634   virtual int oop_oop_iterate_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) = 0;
 635   virtual int oop_oop_iterate_v_m(oop obj, ExtendedOopClosure* blk, MemRegion mr) {
 636     return oop_oop_iterate_m(obj, blk, mr);
 637   }
 638 
 639   // Versions of the above iterators specialized to particular subtypes
 640   // of OopClosure, to avoid closure virtual calls.
 641 #define Klass_OOP_OOP_ITERATE_DECL(OopClosureType, nv_suffix)                \
 642   virtual int oop_oop_iterate##nv_suffix(oop obj, OopClosureType* blk) {     \
 643     /* Default implementation reverts to general version. */                 \
 644     return oop_oop_iterate(obj, blk);                                        \
 645   }                                                                          \
 646                                                                              \
 647   /* Iterates "blk" over all the oops in "obj" (of type "this") within "mr". \
 648      (I don't see why the _m should be required, but without it the Solaris  \
 649      C++ gives warning messages about overridings of the "oop_oop_iterate"   \
 650      defined above "hiding" this virtual function.  (DLD, 6/20/00)) */       \
 651   virtual int oop_oop_iterate##nv_suffix##_m(oop obj,                        \
 652                                              OopClosureType* blk,            \
 653                                              MemRegion mr) {                 \
 654     return oop_oop_iterate_m(obj, blk, mr);                                  \
 655   }
 656 
 657   SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_DECL)
 658   SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_DECL)
 659 
 660 #if INCLUDE_ALL_GCS
 661 #define Klass_OOP_OOP_ITERATE_BACKWARDS_DECL(OopClosureType, nv_suffix)      \
 662   virtual int oop_oop_iterate_backwards##nv_suffix(oop obj,                  \
 663                                                    OopClosureType* blk) {    \
 664     /* Default implementation reverts to general version. */                 \
 665     return oop_oop_iterate_backwards_v(obj, blk);                            \
 666   }
 667 
 668   SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_1(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 669   SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_2(Klass_OOP_OOP_ITERATE_BACKWARDS_DECL)
 670 #endif // INCLUDE_ALL_GCS
 671 
 672   virtual void array_klasses_do(void f(Klass* k)) {}
 673 
 674   // Return self, except for abstract classes with exactly 1
 675   // implementor.  Then return the 1 concrete implementation.
 676   Klass *up_cast_abstract();
 677 
 678   // klass name
 679   Symbol* name() const                   { return _name; }
 680   void set_name(Symbol* n);
 681 
 682  public:
 683   // jvm support
 684   virtual jint compute_modifier_flags(TRAPS) const;
 685 
 686   // JVMTI support
 687   virtual jint jvmti_class_status() const;
 688 
 689   // Printing
 690   virtual void print_on(outputStream* st) const;
 691 
 692   virtual void oop_print_value_on(oop obj, outputStream* st);
 693   virtual void oop_print_on      (oop obj, outputStream* st);
 694 
 695   virtual const char* internal_name() const = 0;
 696 
 697   // Verification
 698   virtual void verify_on(outputStream* st, bool check_dictionary);
 699   void verify(bool check_dictionary = true) { verify_on(tty, check_dictionary); }
 700 
 701 #ifndef PRODUCT
 702   void verify_vtable_index(int index);
 703 #endif
 704 
 705   virtual void oop_verify_on(oop obj, outputStream* st);
 706 
 707  private:
 708   // barriers used by klass_oop_store
 709   void klass_update_barrier_set(oop v);
 710   void klass_update_barrier_set_pre(void* p, oop v);
 711 };
 712 
 713 #endif // SHARE_VM_OOPS_KLASS_HPP
--- EOF ---