1 /*
   2  * Copyright (c) 1997, 2017, 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 #include "precompiled.hpp"
  26 #include "classfile/dictionary.hpp"
  27 #include "classfile/javaClasses.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "gc/shared/collectedHeap.inline.hpp"
  31 #include "logging/log.hpp"
  32 #include "memory/heapInspection.hpp"
  33 #include "memory/metadataFactory.hpp"
  34 #include "memory/oopFactory.hpp"
  35 #include "memory/resourceArea.hpp"
  36 #include "oops/instanceKlass.hpp"
  37 #include "oops/klass.inline.hpp"
  38 #include "oops/oop.inline.hpp"
  39 #include "runtime/atomic.hpp"
  40 #include "runtime/orderAccess.inline.hpp"
  41 #include "trace/traceMacros.hpp"
  42 #include "utilities/macros.hpp"
  43 #include "utilities/stack.inline.hpp"
  44 #if INCLUDE_ALL_GCS
  45 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  46 #endif // INCLUDE_ALL_GCS
  47 
  48 bool Klass::is_cloneable() const {
  49   return _access_flags.is_cloneable_fast() ||
  50          is_subtype_of(SystemDictionary::Cloneable_klass());
  51 }
  52 
  53 void Klass::set_is_cloneable() {
  54   if (name() != vmSymbols::java_lang_invoke_MemberName()) {
  55     _access_flags.set_is_cloneable_fast();
  56   } else {
  57     assert(is_final(), "no subclasses allowed");
  58     // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
  59   }
  60 }
  61 
  62 void Klass::set_name(Symbol* n) {
  63   _name = n;
  64   if (_name != NULL) _name->increment_refcount();
  65 }
  66 
  67 bool Klass::is_subclass_of(const Klass* k) const {
  68   // Run up the super chain and check
  69   if (this == k) return true;
  70 
  71   Klass* t = const_cast<Klass*>(this)->super();
  72 
  73   while (t != NULL) {
  74     if (t == k) return true;
  75     t = t->super();
  76   }
  77   return false;
  78 }
  79 
  80 bool Klass::search_secondary_supers(Klass* k) const {
  81   // Put some extra logic here out-of-line, before the search proper.
  82   // This cuts down the size of the inline method.
  83 
  84   // This is necessary, since I am never in my own secondary_super list.
  85   if (this == k)
  86     return true;
  87   // Scan the array-of-objects for a match
  88   int cnt = secondary_supers()->length();
  89   for (int i = 0; i < cnt; i++) {
  90     if (secondary_supers()->at(i) == k) {
  91       ((Klass*)this)->set_secondary_super_cache(k);
  92       return true;
  93     }
  94   }
  95   return false;
  96 }
  97 
  98 // Return self, except for abstract classes with exactly 1
  99 // implementor.  Then return the 1 concrete implementation.
 100 Klass *Klass::up_cast_abstract() {
 101   Klass *r = this;
 102   while( r->is_abstract() ) {   // Receiver is abstract?
 103     Klass *s = r->subklass();   // Check for exactly 1 subklass
 104     if( !s || s->next_sibling() ) // Oops; wrong count; give up
 105       return this;              // Return 'this' as a no-progress flag
 106     r = s;                    // Loop till find concrete class
 107   }
 108   return r;                   // Return the 1 concrete class
 109 }
 110 
 111 // Find LCA in class hierarchy
 112 Klass *Klass::LCA( Klass *k2 ) {
 113   Klass *k1 = this;
 114   while( 1 ) {
 115     if( k1->is_subtype_of(k2) ) return k2;
 116     if( k2->is_subtype_of(k1) ) return k1;
 117     k1 = k1->super();
 118     k2 = k2->super();
 119   }
 120 }
 121 
 122 
 123 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
 124   ResourceMark rm(THREAD);
 125   THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
 126             : vmSymbols::java_lang_InstantiationException(), external_name());
 127 }
 128 
 129 
 130 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
 131   THROW(vmSymbols::java_lang_ArrayStoreException());
 132 }
 133 
 134 
 135 void Klass::initialize(TRAPS) {
 136   ShouldNotReachHere();
 137 }
 138 
 139 bool Klass::compute_is_subtype_of(Klass* k) {
 140   assert(k->is_klass(), "argument must be a class");
 141   return is_subclass_of(k);
 142 }
 143 
 144 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
 145 #ifdef ASSERT
 146   tty->print_cr("Error: find_field called on a klass oop."
 147                 " Likely error: reflection method does not correctly"
 148                 " wrap return value in a mirror object.");
 149 #endif
 150   ShouldNotReachHere();
 151   return NULL;
 152 }
 153 
 154 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature, OverpassLookupMode overpass_mode) const {
 155 #ifdef ASSERT
 156   tty->print_cr("Error: uncached_lookup_method called on a klass oop."
 157                 " Likely error: reflection method does not correctly"
 158                 " wrap return value in a mirror object.");
 159 #endif
 160   ShouldNotReachHere();
 161   return NULL;
 162 }
 163 
 164 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
 165   return Metaspace::allocate(loader_data, word_size, /*read_only*/false,
 166                              MetaspaceObj::ClassType, THREAD);
 167 }
 168 
 169 // "Normal" instantiation is preceeded by a MetaspaceObj allocation
 170 // which zeros out memory - calloc equivalent.
 171 // The constructor is also used from CppVtableCloner,
 172 // which doesn't zero out the memory before calling the constructor.
 173 // Need to set the _java_mirror field explicitly to not hit an assert that the field
 174 // should be NULL before setting it.
 175 Klass::Klass() : _prototype_header(markOopDesc::prototype()),
 176                  _shared_class_path_index(-1),
 177                  _java_mirror(NULL) {
 178 
 179   _primary_supers[0] = this;
 180   set_super_check_offset(in_bytes(primary_supers_offset()));
 181 }
 182 
 183 jint Klass::array_layout_helper(BasicType etype) {
 184   assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
 185   // Note that T_ARRAY is not allowed here.
 186   int  hsize = arrayOopDesc::base_offset_in_bytes(etype);
 187   int  esize = type2aelembytes(etype);
 188   bool isobj = (etype == T_OBJECT);
 189   int  tag   =  isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
 190   int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
 191 
 192   assert(lh < (int)_lh_neutral_value, "must look like an array layout");
 193   assert(layout_helper_is_array(lh), "correct kind");
 194   assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
 195   assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
 196   assert(layout_helper_header_size(lh) == hsize, "correct decode");
 197   assert(layout_helper_element_type(lh) == etype, "correct decode");
 198   assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
 199 
 200   return lh;
 201 }
 202 
 203 bool Klass::can_be_primary_super_slow() const {
 204   if (super() == NULL)
 205     return true;
 206   else if (super()->super_depth() >= primary_super_limit()-1)
 207     return false;
 208   else
 209     return true;
 210 }
 211 
 212 void Klass::initialize_supers(Klass* k, TRAPS) {
 213   if (FastSuperclassLimit == 0) {
 214     // None of the other machinery matters.
 215     set_super(k);
 216     return;
 217   }
 218   if (k == NULL) {
 219     set_super(NULL);
 220     _primary_supers[0] = this;
 221     assert(super_depth() == 0, "Object must already be initialized properly");
 222   } else if (k != super() || k == SystemDictionary::Object_klass()) {
 223     assert(super() == NULL || super() == SystemDictionary::Object_klass(),
 224            "initialize this only once to a non-trivial value");
 225     set_super(k);
 226     Klass* sup = k;
 227     int sup_depth = sup->super_depth();
 228     juint my_depth  = MIN2(sup_depth + 1, (int)primary_super_limit());
 229     if (!can_be_primary_super_slow())
 230       my_depth = primary_super_limit();
 231     for (juint i = 0; i < my_depth; i++) {
 232       _primary_supers[i] = sup->_primary_supers[i];
 233     }
 234     Klass* *super_check_cell;
 235     if (my_depth < primary_super_limit()) {
 236       _primary_supers[my_depth] = this;
 237       super_check_cell = &_primary_supers[my_depth];
 238     } else {
 239       // Overflow of the primary_supers array forces me to be secondary.
 240       super_check_cell = &_secondary_super_cache;
 241     }
 242     set_super_check_offset((address)super_check_cell - (address) this);
 243 
 244 #ifdef ASSERT
 245     {
 246       juint j = super_depth();
 247       assert(j == my_depth, "computed accessor gets right answer");
 248       Klass* t = this;
 249       while (!t->can_be_primary_super()) {
 250         t = t->super();
 251         j = t->super_depth();
 252       }
 253       for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
 254         assert(primary_super_of_depth(j1) == NULL, "super list padding");
 255       }
 256       while (t != NULL) {
 257         assert(primary_super_of_depth(j) == t, "super list initialization");
 258         t = t->super();
 259         --j;
 260       }
 261       assert(j == (juint)-1, "correct depth count");
 262     }
 263 #endif
 264   }
 265 
 266   if (secondary_supers() == NULL) {
 267 
 268     // Now compute the list of secondary supertypes.
 269     // Secondaries can occasionally be on the super chain,
 270     // if the inline "_primary_supers" array overflows.
 271     int extras = 0;
 272     Klass* p;
 273     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
 274       ++extras;
 275     }
 276 
 277     ResourceMark rm(THREAD);  // need to reclaim GrowableArrays allocated below
 278 
 279     // Compute the "real" non-extra secondaries.
 280     GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras);
 281     if (secondaries == NULL) {
 282       // secondary_supers set by compute_secondary_supers
 283       return;
 284     }
 285 
 286     GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
 287 
 288     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
 289       int i;                    // Scan for overflow primaries being duplicates of 2nd'arys
 290 
 291       // This happens frequently for very deeply nested arrays: the
 292       // primary superclass chain overflows into the secondary.  The
 293       // secondary list contains the element_klass's secondaries with
 294       // an extra array dimension added.  If the element_klass's
 295       // secondary list already contains some primary overflows, they
 296       // (with the extra level of array-ness) will collide with the
 297       // normal primary superclass overflows.
 298       for( i = 0; i < secondaries->length(); i++ ) {
 299         if( secondaries->at(i) == p )
 300           break;
 301       }
 302       if( i < secondaries->length() )
 303         continue;               // It's a dup, don't put it in
 304       primaries->push(p);
 305     }
 306     // Combine the two arrays into a metadata object to pack the array.
 307     // The primaries are added in the reverse order, then the secondaries.
 308     int new_length = primaries->length() + secondaries->length();
 309     Array<Klass*>* s2 = MetadataFactory::new_array<Klass*>(
 310                                        class_loader_data(), new_length, CHECK);
 311     int fill_p = primaries->length();
 312     for (int j = 0; j < fill_p; j++) {
 313       s2->at_put(j, primaries->pop());  // add primaries in reverse order.
 314     }
 315     for( int j = 0; j < secondaries->length(); j++ ) {
 316       s2->at_put(j+fill_p, secondaries->at(j));  // add secondaries on the end.
 317     }
 318 
 319   #ifdef ASSERT
 320       // We must not copy any NULL placeholders left over from bootstrap.
 321     for (int j = 0; j < s2->length(); j++) {
 322       assert(s2->at(j) != NULL, "correct bootstrapping order");
 323     }
 324   #endif
 325 
 326     set_secondary_supers(s2);
 327   }
 328 }
 329 
 330 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots) {
 331   assert(num_extra_slots == 0, "override for complex klasses");
 332   set_secondary_supers(Universe::the_empty_klass_array());
 333   return NULL;
 334 }
 335 
 336 
 337 InstanceKlass* Klass::superklass() const {
 338   assert(super() == NULL || super()->is_instance_klass(), "must be instance klass");
 339   return _super == NULL ? NULL : InstanceKlass::cast(_super);
 340 }
 341 
 342 void Klass::set_subklass(Klass* s) {
 343   assert(s != this, "sanity check");
 344   _subklass = s;
 345 }
 346 
 347 void Klass::set_next_sibling(Klass* s) {
 348   assert(s != this, "sanity check");
 349   _next_sibling = s;
 350 }
 351 
 352 void Klass::append_to_sibling_list() {
 353   debug_only(verify();)
 354   // add ourselves to superklass' subklass list
 355   InstanceKlass* super = superklass();
 356   if (super == NULL) return;        // special case: class Object
 357   assert((!super->is_interface()    // interfaces cannot be supers
 358           && (super->superklass() == NULL || !is_interface())),
 359          "an interface can only be a subklass of Object");
 360   Klass* prev_first_subklass = super->subklass();
 361   if (prev_first_subklass != NULL) {
 362     // set our sibling to be the superklass' previous first subklass
 363     set_next_sibling(prev_first_subklass);
 364   }
 365   // make ourselves the superklass' first subklass
 366   super->set_subklass(this);
 367   debug_only(verify();)
 368 }
 369 
 370 bool Klass::is_loader_alive(BoolObjectClosure* is_alive) {
 371 #ifdef ASSERT
 372   // The class is alive iff the class loader is alive.
 373   oop loader = class_loader();
 374   bool loader_alive = (loader == NULL) || is_alive->do_object_b(loader);
 375 #endif // ASSERT
 376 
 377   // The class is alive if it's mirror is alive (which should be marked if the
 378   // loader is alive) unless it's an anoymous class.
 379   bool mirror_alive = is_alive->do_object_b(java_mirror());
 380   assert(!mirror_alive || loader_alive, "loader must be alive if the mirror is"
 381                         " but not the other way around with anonymous classes");
 382   return mirror_alive;
 383 }
 384 
 385 void Klass::clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses) {
 386   if (!ClassUnloading) {
 387     return;
 388   }
 389 
 390   Klass* root = SystemDictionary::Object_klass();
 391   Stack<Klass*, mtGC> stack;
 392 
 393   stack.push(root);
 394   while (!stack.is_empty()) {
 395     Klass* current = stack.pop();
 396 
 397     assert(current->is_loader_alive(is_alive), "just checking, this should be live");
 398 
 399     // Find and set the first alive subklass
 400     Klass* sub = current->subklass();
 401     while (sub != NULL && !sub->is_loader_alive(is_alive)) {
 402 #ifndef PRODUCT
 403       if (log_is_enabled(Trace, class, unload)) {
 404         ResourceMark rm;
 405         log_trace(class, unload)("unlinking class (subclass): %s", sub->external_name());
 406       }
 407 #endif
 408       sub = sub->next_sibling();
 409     }
 410     current->set_subklass(sub);
 411     if (sub != NULL) {
 412       stack.push(sub);
 413     }
 414 
 415     // Find and set the first alive sibling
 416     Klass* sibling = current->next_sibling();
 417     while (sibling != NULL && !sibling->is_loader_alive(is_alive)) {
 418       if (log_is_enabled(Trace, class, unload)) {
 419         ResourceMark rm;
 420         log_trace(class, unload)("[Unlinking class (sibling) %s]", sibling->external_name());
 421       }
 422       sibling = sibling->next_sibling();
 423     }
 424     current->set_next_sibling(sibling);
 425     if (sibling != NULL) {
 426       stack.push(sibling);
 427     }
 428 
 429     // Clean the implementors list and method data.
 430     if (clean_alive_klasses && current->is_instance_klass()) {
 431       InstanceKlass* ik = InstanceKlass::cast(current);
 432       ik->clean_weak_instanceklass_links(is_alive);
 433 
 434       // JVMTI RedefineClasses creates previous versions that are not in
 435       // the class hierarchy, so process them here.
 436       while ((ik = ik->previous_versions()) != NULL) {
 437         ik->clean_weak_instanceklass_links(is_alive);
 438       }
 439     }
 440   }
 441 }
 442 
 443 void Klass::klass_update_barrier_set(oop v) {
 444   record_modified_oops();
 445 }
 446 
 447 // This barrier is used by G1 to remember the old oop values, so
 448 // that we don't forget any objects that were live at the snapshot at
 449 // the beginning. This function is only used when we write oops into Klasses.
 450 void Klass::klass_update_barrier_set_pre(oop* p, oop v) {
 451 #if INCLUDE_ALL_GCS
 452   if (UseG1GC) {
 453     oop obj = *p;
 454     if (obj != NULL) {
 455       G1SATBCardTableModRefBS::enqueue(obj);
 456     }
 457   }
 458 #endif
 459 }
 460 
 461 void Klass::klass_oop_store(oop* p, oop v) {
 462   assert(!Universe::heap()->is_in_reserved((void*)p), "Should store pointer into metadata");
 463   assert(v == NULL || Universe::heap()->is_in_reserved((void*)v), "Should store pointer to an object");
 464 
 465   // do the store
 466   if (always_do_update_barrier) {
 467     klass_oop_store((volatile oop*)p, v);
 468   } else {
 469     klass_update_barrier_set_pre(p, v);
 470     *p = v;
 471     klass_update_barrier_set(v);
 472   }
 473 }
 474 
 475 void Klass::klass_oop_store(volatile oop* p, oop v) {
 476   assert(!Universe::heap()->is_in_reserved((void*)p), "Should store pointer into metadata");
 477   assert(v == NULL || Universe::heap()->is_in_reserved((void*)v), "Should store pointer to an object");
 478 
 479   klass_update_barrier_set_pre((oop*)p, v); // Cast away volatile.
 480   OrderAccess::release_store_ptr(p, v);
 481   klass_update_barrier_set(v);
 482 }
 483 
 484 void Klass::oops_do(OopClosure* cl) {
 485   cl->do_oop(&_java_mirror);
 486 }
 487 
 488 void Klass::remove_unshareable_info() {
 489   assert (DumpSharedSpaces, "only called for DumpSharedSpaces");
 490   TRACE_REMOVE_ID(this);
 491 
 492   set_subklass(NULL);
 493   set_next_sibling(NULL);
 494   // Clear the java mirror
 495   set_java_mirror(NULL);
 496   set_next_link(NULL);
 497 
 498   // Null out class_loader_data because we don't share that yet.
 499   set_class_loader_data(NULL);
 500   set_is_shared();
 501 }
 502 
 503 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
 504   assert(is_klass(), "ensure C++ vtable is restored");
 505   assert(is_shared(), "must be set");
 506   TRACE_RESTORE_ID(this);
 507 
 508   // If an exception happened during CDS restore, some of these fields may already be
 509   // set.  We leave the class on the CLD list, even if incomplete so that we don't
 510   // modify the CLD list outside a safepoint.
 511   if (class_loader_data() == NULL) {
 512     // Restore class_loader_data to the null class loader data
 513     set_class_loader_data(loader_data);
 514 
 515     // Add to null class loader list first before creating the mirror
 516     // (same order as class file parsing)
 517     loader_data->add_class(this);
 518   }
 519 
 520   // Recreate the class mirror.
 521   // Only recreate it if not present.  A previous attempt to restore may have
 522   // gotten an OOM later but keep the mirror if it was created.
 523   if (java_mirror() == NULL) {
 524     Handle loader(THREAD, loader_data->class_loader());
 525     ModuleEntry* module_entry = NULL;
 526     Klass* k = this;
 527     if (k->is_objArray_klass()) {
 528       k = ObjArrayKlass::cast(k)->bottom_klass();
 529     }
 530     // Obtain klass' module.
 531     if (k->is_instance_klass()) {
 532       InstanceKlass* ik = (InstanceKlass*) k;
 533       module_entry = ik->module();
 534     } else {
 535       module_entry = ModuleEntryTable::javabase_moduleEntry();
 536     }
 537     // Obtain java.lang.reflect.Module, if available
 538     Handle module_handle(THREAD, ((module_entry != NULL) ? JNIHandles::resolve(module_entry->module()) : (oop)NULL));
 539     java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, CHECK);
 540   }
 541 }
 542 
 543 Klass* Klass::array_klass_or_null(int rank) {
 544   EXCEPTION_MARK;
 545   // No exception can be thrown by array_klass_impl when called with or_null == true.
 546   // (In anycase, the execption mark will fail if it do so)
 547   return array_klass_impl(true, rank, THREAD);
 548 }
 549 
 550 
 551 Klass* Klass::array_klass_or_null() {
 552   EXCEPTION_MARK;
 553   // No exception can be thrown by array_klass_impl when called with or_null == true.
 554   // (In anycase, the execption mark will fail if it do so)
 555   return array_klass_impl(true, THREAD);
 556 }
 557 
 558 
 559 Klass* Klass::array_klass_impl(bool or_null, int rank, TRAPS) {
 560   fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
 561   return NULL;
 562 }
 563 
 564 
 565 Klass* Klass::array_klass_impl(bool or_null, TRAPS) {
 566   fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
 567   return NULL;
 568 }
 569 
 570 oop Klass::class_loader() const { return class_loader_data()->class_loader(); }
 571 
 572 // In product mode, this function doesn't have virtual function calls so
 573 // there might be some performance advantage to handling InstanceKlass here.
 574 const char* Klass::external_name() const {
 575   if (is_instance_klass()) {
 576     const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
 577     if (ik->is_anonymous()) {
 578       intptr_t hash = 0;
 579       if (ik->java_mirror() != NULL) {
 580         // java_mirror might not be created yet, return 0 as hash.
 581         hash = ik->java_mirror()->identity_hash();
 582       }
 583       char     hash_buf[40];
 584       sprintf(hash_buf, "/" UINTX_FORMAT, (uintx)hash);
 585       size_t   hash_len = strlen(hash_buf);
 586 
 587       size_t result_len = name()->utf8_length();
 588       char*  result     = NEW_RESOURCE_ARRAY(char, result_len + hash_len + 1);
 589       name()->as_klass_external_name(result, (int) result_len + 1);
 590       assert(strlen(result) == result_len, "");
 591       strcpy(result + result_len, hash_buf);
 592       assert(strlen(result) == result_len + hash_len, "");
 593       return result;
 594     }
 595   }
 596   if (name() == NULL)  return "<unknown>";
 597   return name()->as_klass_external_name();
 598 }
 599 
 600 
 601 const char* Klass::signature_name() const {
 602   if (name() == NULL)  return "<unknown>";
 603   return name()->as_C_string();
 604 }
 605 
 606 // Unless overridden, modifier_flags is 0.
 607 jint Klass::compute_modifier_flags(TRAPS) const {
 608   return 0;
 609 }
 610 
 611 int Klass::atomic_incr_biased_lock_revocation_count() {
 612   return (int) Atomic::add(1, &_biased_lock_revocation_count);
 613 }
 614 
 615 // Unless overridden, jvmti_class_status has no flags set.
 616 jint Klass::jvmti_class_status() const {
 617   return 0;
 618 }
 619 
 620 
 621 // Printing
 622 
 623 void Klass::print_on(outputStream* st) const {
 624   ResourceMark rm;
 625   // print title
 626   st->print("%s", internal_name());
 627   print_address_on(st);
 628   st->cr();
 629 }
 630 
 631 void Klass::oop_print_on(oop obj, outputStream* st) {
 632   ResourceMark rm;
 633   // print title
 634   st->print_cr("%s ", internal_name());
 635   obj->print_address_on(st);
 636 
 637   if (WizardMode) {
 638      // print header
 639      obj->mark()->print_on(st);
 640   }
 641 
 642   // print class
 643   st->print(" - klass: ");
 644   obj->klass()->print_value_on(st);
 645   st->cr();
 646 }
 647 
 648 void Klass::oop_print_value_on(oop obj, outputStream* st) {
 649   // print title
 650   ResourceMark rm;              // Cannot print in debug mode without this
 651   st->print("%s", internal_name());
 652   obj->print_address_on(st);
 653 }
 654 
 655 #if INCLUDE_SERVICES
 656 // Size Statistics
 657 void Klass::collect_statistics(KlassSizeStats *sz) const {
 658   sz->_klass_bytes = sz->count(this);
 659   sz->_mirror_bytes = sz->count(java_mirror());
 660   sz->_secondary_supers_bytes = sz->count_array(secondary_supers());
 661 
 662   sz->_ro_bytes += sz->_secondary_supers_bytes;
 663   sz->_rw_bytes += sz->_klass_bytes + sz->_mirror_bytes;
 664 }
 665 #endif // INCLUDE_SERVICES
 666 
 667 // Verification
 668 
 669 void Klass::verify_on(outputStream* st) {
 670 
 671   // This can be expensive, but it is worth checking that this klass is actually
 672   // in the CLD graph but not in production.
 673   assert(Metaspace::contains((address)this), "Should be");
 674 
 675   guarantee(this->is_klass(),"should be klass");
 676 
 677   if (super() != NULL) {
 678     guarantee(super()->is_klass(), "should be klass");
 679   }
 680   if (secondary_super_cache() != NULL) {
 681     Klass* ko = secondary_super_cache();
 682     guarantee(ko->is_klass(), "should be klass");
 683   }
 684   for ( uint i = 0; i < primary_super_limit(); i++ ) {
 685     Klass* ko = _primary_supers[i];
 686     if (ko != NULL) {
 687       guarantee(ko->is_klass(), "should be klass");
 688     }
 689   }
 690 
 691   if (java_mirror() != NULL) {
 692     guarantee(java_mirror()->is_oop(), "should be instance");
 693   }
 694 }
 695 
 696 void Klass::oop_verify_on(oop obj, outputStream* st) {
 697   guarantee(obj->is_oop(),  "should be oop");
 698   guarantee(obj->klass()->is_klass(), "klass field is not a klass");
 699 }
 700 
 701 klassVtable Klass::vtable() const {
 702   return klassVtable(const_cast<Klass*>(this), start_of_vtable(), vtable_length() / vtableEntry::size());
 703 }
 704 
 705 vtableEntry* Klass::start_of_vtable() const {
 706   return (vtableEntry*) ((address)this + in_bytes(vtable_start_offset()));
 707 }
 708 
 709 Method* Klass::method_at_vtable(int index)  {
 710 #ifndef PRODUCT
 711   assert(index >= 0, "valid vtable index");
 712   if (DebugVtables) {
 713     verify_vtable_index(index);
 714   }
 715 #endif
 716   return start_of_vtable()[index].method();
 717 }
 718 
 719 ByteSize Klass::vtable_start_offset() {
 720   return in_ByteSize(InstanceKlass::header_size() * wordSize);
 721 }
 722 
 723 #ifndef PRODUCT
 724 
 725 bool Klass::verify_vtable_index(int i) {
 726   int limit = vtable_length()/vtableEntry::size();
 727   assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
 728   return true;
 729 }
 730 
 731 bool Klass::verify_itable_index(int i) {
 732   assert(is_instance_klass(), "");
 733   int method_count = klassItable::method_count_for_interface(this);
 734   assert(i >= 0 && i < method_count, "index out of bounds");
 735   return true;
 736 }
 737 
 738 #endif