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 #include "precompiled.hpp"
  26 #include "classfile/classLoaderData.inline.hpp"
  27 #include "classfile/dictionary.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "gc/shared/collectedHeap.inline.hpp"
  32 #include "logging/log.hpp"
  33 #include "memory/heapInspection.hpp"
  34 #include "memory/metadataFactory.hpp"
  35 #include "memory/metaspaceClosure.hpp"
  36 #include "memory/metaspaceShared.hpp"
  37 #include "memory/oopFactory.hpp"
  38 #include "memory/resourceArea.hpp"
  39 #include "oops/compressedOops.inline.hpp"
  40 #include "oops/instanceKlass.hpp"
  41 #include "oops/klass.inline.hpp"
  42 #include "oops/oop.inline.hpp"
  43 #include "oops/oopHandle.inline.hpp"
  44 #include "runtime/atomic.hpp"
  45 #include "runtime/handles.inline.hpp"
  46 #include "runtime/orderAccess.inline.hpp"
  47 #include "trace/traceMacros.hpp"
  48 #include "utilities/macros.hpp"
  49 #include "utilities/stack.inline.hpp"
  50 
  51 void Klass::set_java_mirror(Handle m) {
  52   assert(!m.is_null(), "New mirror should never be null.");
  53   assert(_java_mirror.resolve() == NULL, "should only be used to initialize mirror");
  54   _java_mirror = class_loader_data()->add_handle(m);
  55 }
  56 
  57 oop Klass::java_mirror() const {
  58   return _java_mirror.resolve();
  59 }
  60 
  61 bool Klass::is_cloneable() const {
  62   return _access_flags.is_cloneable_fast() ||
  63          is_subtype_of(SystemDictionary::Cloneable_klass());
  64 }
  65 
  66 void Klass::set_is_cloneable() {
  67   if (name() == vmSymbols::java_lang_invoke_MemberName()) {
  68     assert(is_final(), "no subclasses allowed");
  69     // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
  70   } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
  71     // Reference cloning should not be intrinsified and always happen in JVM_Clone.
  72   } else {
  73     _access_flags.set_is_cloneable_fast();
  74   }
  75 }
  76 
  77 void Klass::set_name(Symbol* n) {
  78   _name = n;
  79   if (_name != NULL) _name->increment_refcount();
  80 }
  81 
  82 bool Klass::is_subclass_of(const Klass* k) const {
  83   // Run up the super chain and check
  84   if (this == k) return true;
  85 
  86   Klass* t = const_cast<Klass*>(this)->super();
  87 
  88   while (t != NULL) {
  89     if (t == k) return true;
  90     t = t->super();
  91   }
  92   return false;
  93 }
  94 
  95 bool Klass::search_secondary_supers(Klass* k) const {
  96   // Put some extra logic here out-of-line, before the search proper.
  97   // This cuts down the size of the inline method.
  98 
  99   // This is necessary, since I am never in my own secondary_super list.
 100   if (this == k)
 101     return true;
 102   // Scan the array-of-objects for a match
 103   int cnt = secondary_supers()->length();
 104   for (int i = 0; i < cnt; i++) {
 105     if (secondary_supers()->at(i) == k) {
 106       ((Klass*)this)->set_secondary_super_cache(k);
 107       return true;
 108     }
 109   }
 110   return false;
 111 }
 112 
 113 // Return self, except for abstract classes with exactly 1
 114 // implementor.  Then return the 1 concrete implementation.
 115 Klass *Klass::up_cast_abstract() {
 116   Klass *r = this;
 117   while( r->is_abstract() ) {   // Receiver is abstract?
 118     Klass *s = r->subklass();   // Check for exactly 1 subklass
 119     if( !s || s->next_sibling() ) // Oops; wrong count; give up
 120       return this;              // Return 'this' as a no-progress flag
 121     r = s;                    // Loop till find concrete class
 122   }
 123   return r;                   // Return the 1 concrete class
 124 }
 125 
 126 // Find LCA in class hierarchy
 127 Klass *Klass::LCA( Klass *k2 ) {
 128   Klass *k1 = this;
 129   while( 1 ) {
 130     if( k1->is_subtype_of(k2) ) return k2;
 131     if( k2->is_subtype_of(k1) ) return k1;
 132     k1 = k1->super();
 133     k2 = k2->super();
 134   }
 135 }
 136 
 137 
 138 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
 139   ResourceMark rm(THREAD);
 140   THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
 141             : vmSymbols::java_lang_InstantiationException(), external_name());
 142 }
 143 
 144 
 145 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
 146   THROW(vmSymbols::java_lang_ArrayStoreException());
 147 }
 148 
 149 
 150 void Klass::initialize(TRAPS) {
 151   ShouldNotReachHere();
 152 }
 153 
 154 bool Klass::compute_is_subtype_of(Klass* k) {
 155   assert(k->is_klass(), "argument must be a class");
 156   return is_subclass_of(k);
 157 }
 158 
 159 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
 160 #ifdef ASSERT
 161   tty->print_cr("Error: find_field called on a klass oop."
 162                 " Likely error: reflection method does not correctly"
 163                 " wrap return value in a mirror object.");
 164 #endif
 165   ShouldNotReachHere();
 166   return NULL;
 167 }
 168 
 169 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature, OverpassLookupMode overpass_mode) const {
 170 #ifdef ASSERT
 171   tty->print_cr("Error: uncached_lookup_method called on a klass oop."
 172                 " Likely error: reflection method does not correctly"
 173                 " wrap return value in a mirror object.");
 174 #endif
 175   ShouldNotReachHere();
 176   return NULL;
 177 }
 178 
 179 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
 180   return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
 181 }
 182 
 183 // "Normal" instantiation is preceeded by a MetaspaceObj allocation
 184 // which zeros out memory - calloc equivalent.
 185 // The constructor is also used from CppVtableCloner,
 186 // which doesn't zero out the memory before calling the constructor.
 187 // Need to set the _java_mirror field explicitly to not hit an assert that the field
 188 // should be NULL before setting it.
 189 Klass::Klass() : _prototype_header(markOopDesc::prototype()),
 190                  _shared_class_path_index(-1),
 191                  _java_mirror(NULL) {
 192   CDS_ONLY(_shared_class_flags = 0;)
 193   CDS_JAVA_HEAP_ONLY(_archived_mirror = 0;)
 194   _primary_supers[0] = this;
 195   set_super_check_offset(in_bytes(primary_supers_offset()));
 196 }
 197 
 198 jint Klass::array_layout_helper(BasicType etype) {
 199   assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
 200   // Note that T_ARRAY is not allowed here.
 201   int  hsize = arrayOopDesc::base_offset_in_bytes(etype);
 202   int  esize = type2aelembytes(etype);
 203   bool isobj = (etype == T_OBJECT);
 204   int  tag   =  isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
 205   int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
 206 
 207   assert(lh < (int)_lh_neutral_value, "must look like an array layout");
 208   assert(layout_helper_is_array(lh), "correct kind");
 209   assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
 210   assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
 211   assert(layout_helper_header_size(lh) == hsize, "correct decode");
 212   assert(layout_helper_element_type(lh) == etype, "correct decode");
 213   assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
 214 
 215   return lh;
 216 }
 217 
 218 bool Klass::can_be_primary_super_slow() const {
 219   if (super() == NULL)
 220     return true;
 221   else if (super()->super_depth() >= primary_super_limit()-1)
 222     return false;
 223   else
 224     return true;
 225 }
 226 
 227 void Klass::initialize_supers(Klass* k, TRAPS) {
 228   if (FastSuperclassLimit == 0) {
 229     // None of the other machinery matters.
 230     set_super(k);
 231     return;
 232   }
 233   if (k == NULL) {
 234     set_super(NULL);
 235     _primary_supers[0] = this;
 236     assert(super_depth() == 0, "Object must already be initialized properly");
 237   } else if (k != super() || k == SystemDictionary::Object_klass()) {
 238     assert(super() == NULL || super() == SystemDictionary::Object_klass(),
 239            "initialize this only once to a non-trivial value");
 240     set_super(k);
 241     Klass* sup = k;
 242     int sup_depth = sup->super_depth();
 243     juint my_depth  = MIN2(sup_depth + 1, (int)primary_super_limit());
 244     if (!can_be_primary_super_slow())
 245       my_depth = primary_super_limit();
 246     for (juint i = 0; i < my_depth; i++) {
 247       _primary_supers[i] = sup->_primary_supers[i];
 248     }
 249     Klass* *super_check_cell;
 250     if (my_depth < primary_super_limit()) {
 251       _primary_supers[my_depth] = this;
 252       super_check_cell = &_primary_supers[my_depth];
 253     } else {
 254       // Overflow of the primary_supers array forces me to be secondary.
 255       super_check_cell = &_secondary_super_cache;
 256     }
 257     set_super_check_offset((address)super_check_cell - (address) this);
 258 
 259 #ifdef ASSERT
 260     {
 261       juint j = super_depth();
 262       assert(j == my_depth, "computed accessor gets right answer");
 263       Klass* t = this;
 264       while (!t->can_be_primary_super()) {
 265         t = t->super();
 266         j = t->super_depth();
 267       }
 268       for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
 269         assert(primary_super_of_depth(j1) == NULL, "super list padding");
 270       }
 271       while (t != NULL) {
 272         assert(primary_super_of_depth(j) == t, "super list initialization");
 273         t = t->super();
 274         --j;
 275       }
 276       assert(j == (juint)-1, "correct depth count");
 277     }
 278 #endif
 279   }
 280 
 281   if (secondary_supers() == NULL) {
 282 
 283     // Now compute the list of secondary supertypes.
 284     // Secondaries can occasionally be on the super chain,
 285     // if the inline "_primary_supers" array overflows.
 286     int extras = 0;
 287     Klass* p;
 288     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
 289       ++extras;
 290     }
 291 
 292     ResourceMark rm(THREAD);  // need to reclaim GrowableArrays allocated below
 293 
 294     // Compute the "real" non-extra secondaries.
 295     GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras);
 296     if (secondaries == NULL) {
 297       // secondary_supers set by compute_secondary_supers
 298       return;
 299     }
 300 
 301     GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
 302 
 303     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
 304       int i;                    // Scan for overflow primaries being duplicates of 2nd'arys
 305 
 306       // This happens frequently for very deeply nested arrays: the
 307       // primary superclass chain overflows into the secondary.  The
 308       // secondary list contains the element_klass's secondaries with
 309       // an extra array dimension added.  If the element_klass's
 310       // secondary list already contains some primary overflows, they
 311       // (with the extra level of array-ness) will collide with the
 312       // normal primary superclass overflows.
 313       for( i = 0; i < secondaries->length(); i++ ) {
 314         if( secondaries->at(i) == p )
 315           break;
 316       }
 317       if( i < secondaries->length() )
 318         continue;               // It's a dup, don't put it in
 319       primaries->push(p);
 320     }
 321     // Combine the two arrays into a metadata object to pack the array.
 322     // The primaries are added in the reverse order, then the secondaries.
 323     int new_length = primaries->length() + secondaries->length();
 324     Array<Klass*>* s2 = MetadataFactory::new_array<Klass*>(
 325                                        class_loader_data(), new_length, CHECK);
 326     int fill_p = primaries->length();
 327     for (int j = 0; j < fill_p; j++) {
 328       s2->at_put(j, primaries->pop());  // add primaries in reverse order.
 329     }
 330     for( int j = 0; j < secondaries->length(); j++ ) {
 331       s2->at_put(j+fill_p, secondaries->at(j));  // add secondaries on the end.
 332     }
 333 
 334   #ifdef ASSERT
 335       // We must not copy any NULL placeholders left over from bootstrap.
 336     for (int j = 0; j < s2->length(); j++) {
 337       assert(s2->at(j) != NULL, "correct bootstrapping order");
 338     }
 339   #endif
 340 
 341     set_secondary_supers(s2);
 342   }
 343 }
 344 
 345 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots) {
 346   assert(num_extra_slots == 0, "override for complex klasses");
 347   set_secondary_supers(Universe::the_empty_klass_array());
 348   return NULL;
 349 }
 350 
 351 
 352 InstanceKlass* Klass::superklass() const {
 353   assert(super() == NULL || super()->is_instance_klass(), "must be instance klass");
 354   return _super == NULL ? NULL : InstanceKlass::cast(_super);
 355 }
 356 
 357 void Klass::set_subklass(Klass* s) {
 358   assert(s != this, "sanity check");
 359   _subklass = s;
 360 }
 361 
 362 void Klass::set_next_sibling(Klass* s) {
 363   assert(s != this, "sanity check");
 364   _next_sibling = s;
 365 }
 366 
 367 void Klass::append_to_sibling_list() {
 368   debug_only(verify();)
 369   // add ourselves to superklass' subklass list
 370   InstanceKlass* super = superklass();
 371   if (super == NULL) return;        // special case: class Object
 372   assert((!super->is_interface()    // interfaces cannot be supers
 373           && (super->superklass() == NULL || !is_interface())),
 374          "an interface can only be a subklass of Object");
 375   Klass* prev_first_subklass = super->subklass();
 376   if (prev_first_subklass != NULL) {
 377     // set our sibling to be the superklass' previous first subklass
 378     set_next_sibling(prev_first_subklass);
 379   }
 380   // make ourselves the superklass' first subklass
 381   super->set_subklass(this);
 382   debug_only(verify();)
 383 }
 384 
 385 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
 386   if (!ClassUnloading || !unloading_occurred) {
 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(), "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()) {
 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()) {
 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();
 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();
 438       }
 439     }
 440   }
 441 }
 442 
 443 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
 444   if (log_is_enabled(Trace, cds)) {
 445     ResourceMark rm;
 446     log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
 447   }
 448 
 449   it->push(&_name);
 450   it->push(&_secondary_super_cache);
 451   it->push(&_secondary_supers);
 452   for (int i = 0; i < _primary_super_limit; i++) {
 453     it->push(&_primary_supers[i]);
 454   }
 455   it->push(&_super);
 456   it->push(&_subklass);
 457   it->push(&_next_sibling);
 458   it->push(&_next_link);
 459 
 460   vtableEntry* vt = start_of_vtable();
 461   for (int i=0; i<vtable_length(); i++) {
 462     it->push(vt[i].method_addr());
 463   }
 464 }
 465 
 466 void Klass::remove_unshareable_info() {
 467   assert (DumpSharedSpaces, "only called for DumpSharedSpaces");
 468   TRACE_REMOVE_ID(this);
 469   if (log_is_enabled(Trace, cds, unshareable)) {
 470     ResourceMark rm;
 471     log_trace(cds, unshareable)("remove: %s", external_name());
 472   }
 473 
 474   set_subklass(NULL);
 475   set_next_sibling(NULL);
 476   set_next_link(NULL);
 477 
 478   // Null out class_loader_data because we don't share that yet.
 479   set_class_loader_data(NULL);
 480   set_is_shared();
 481 }
 482 
 483 void Klass::remove_java_mirror() {
 484   assert (DumpSharedSpaces, "only called for DumpSharedSpaces");
 485   if (log_is_enabled(Trace, cds, unshareable)) {
 486     ResourceMark rm;
 487     log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
 488   }
 489   // Just null out the mirror.  The class_loader_data() no longer exists.
 490   _java_mirror = NULL;
 491 }
 492 
 493 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
 494   assert(is_klass(), "ensure C++ vtable is restored");
 495   assert(is_shared(), "must be set");
 496   TRACE_RESTORE_ID(this);
 497   if (log_is_enabled(Trace, cds, unshareable)) {
 498     ResourceMark rm;
 499     log_trace(cds, unshareable)("restore: %s", external_name());
 500   }
 501 
 502   // If an exception happened during CDS restore, some of these fields may already be
 503   // set.  We leave the class on the CLD list, even if incomplete so that we don't
 504   // modify the CLD list outside a safepoint.
 505   if (class_loader_data() == NULL) {
 506     // Restore class_loader_data to the null class loader data
 507     set_class_loader_data(loader_data);
 508 
 509     // Add to null class loader list first before creating the mirror
 510     // (same order as class file parsing)
 511     loader_data->add_class(this);
 512   }
 513 
 514   Handle loader(THREAD, loader_data->class_loader());
 515   ModuleEntry* module_entry = NULL;
 516   Klass* k = this;
 517   if (k->is_objArray_klass()) {
 518     k = ObjArrayKlass::cast(k)->bottom_klass();
 519   }
 520   // Obtain klass' module.
 521   if (k->is_instance_klass()) {
 522     InstanceKlass* ik = (InstanceKlass*) k;
 523     module_entry = ik->module();
 524   } else {
 525     module_entry = ModuleEntryTable::javabase_moduleEntry();
 526   }
 527   // Obtain java.lang.Module, if available
 528   Handle module_handle(THREAD, ((module_entry != NULL) ? module_entry->module() : (oop)NULL));
 529 
 530   if (this->has_raw_archived_mirror()) {
 531     log_debug(cds, mirror)("%s has raw archived mirror", external_name());
 532     if (MetaspaceShared::open_archive_heap_region_mapped()) {
 533       oop m = archived_java_mirror();
 534       log_debug(cds, mirror)("Archived mirror is: " PTR_FORMAT, p2i(m));
 535       if (m != NULL) {
 536         // mirror is archived, restore
 537         assert(oopDesc::is_archive_object(m), "must be archived mirror object");
 538         Handle m_h(THREAD, m);
 539         java_lang_Class::restore_archived_mirror(this, m_h, loader, module_handle, protection_domain, CHECK);
 540         return;
 541       }
 542     }
 543 
 544     // No archived mirror data
 545     _java_mirror = NULL;
 546     this->clear_has_raw_archived_mirror();
 547   }
 548 
 549   // Only recreate it if not present.  A previous attempt to restore may have
 550   // gotten an OOM later but keep the mirror if it was created.
 551   if (java_mirror() == NULL) {
 552     log_trace(cds, mirror)("Recreate mirror for %s", external_name());
 553     java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, CHECK);
 554   }
 555 }
 556 
 557 #if INCLUDE_CDS_JAVA_HEAP
 558 // Used at CDS dump time to access the archived mirror. No GC barrier.
 559 oop Klass::archived_java_mirror_raw() {
 560   assert(DumpSharedSpaces, "called only during runtime");
 561   assert(has_raw_archived_mirror(), "must have raw archived mirror");
 562   return CompressedOops::decode(_archived_mirror);
 563 }
 564 
 565 // Used at CDS runtime to get the archived mirror from shared class. Uses GC barrier.
 566 oop Klass::archived_java_mirror() {
 567   assert(UseSharedSpaces, "UseSharedSpaces expected.");
 568   assert(has_raw_archived_mirror(), "must have raw archived mirror");
 569   return RootAccess<IN_ARCHIVE_ROOT>::oop_load(&_archived_mirror);
 570 }
 571 
 572 // No GC barrier
 573 void Klass::set_archived_java_mirror_raw(oop m) {
 574   assert(DumpSharedSpaces, "called only during runtime");
 575   _archived_mirror = CompressedOops::encode(m);
 576 }
 577 #endif // INCLUDE_CDS_JAVA_HEAP
 578 
 579 Klass* Klass::array_klass_or_null(int rank) {
 580   EXCEPTION_MARK;
 581   // No exception can be thrown by array_klass_impl when called with or_null == true.
 582   // (In anycase, the execption mark will fail if it do so)
 583   return array_klass_impl(true, rank, THREAD);
 584 }
 585 
 586 
 587 Klass* Klass::array_klass_or_null() {
 588   EXCEPTION_MARK;
 589   // No exception can be thrown by array_klass_impl when called with or_null == true.
 590   // (In anycase, the execption mark will fail if it do so)
 591   return array_klass_impl(true, THREAD);
 592 }
 593 
 594 
 595 Klass* Klass::array_klass_impl(bool or_null, int rank, TRAPS) {
 596   fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
 597   return NULL;
 598 }
 599 
 600 
 601 Klass* Klass::array_klass_impl(bool or_null, TRAPS) {
 602   fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
 603   return NULL;
 604 }
 605 
 606 oop Klass::class_loader() const { return class_loader_data()->class_loader(); }
 607 
 608 // In product mode, this function doesn't have virtual function calls so
 609 // there might be some performance advantage to handling InstanceKlass here.
 610 const char* Klass::external_name() const {
 611   if (is_instance_klass()) {
 612     const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
 613     if (ik->is_anonymous()) {
 614       char addr_buf[20];
 615       jio_snprintf(addr_buf, 20, "/" INTPTR_FORMAT, p2i(ik));
 616       size_t addr_len = strlen(addr_buf);
 617       size_t name_len = name()->utf8_length();
 618       char*  result   = NEW_RESOURCE_ARRAY(char, name_len + addr_len + 1);
 619       name()->as_klass_external_name(result, (int) name_len + 1);
 620       assert(strlen(result) == name_len, "");
 621       strcpy(result + name_len, addr_buf);
 622       assert(strlen(result) == name_len + addr_len, "");
 623       return result;
 624     }
 625   }
 626   if (name() == NULL)  return "<unknown>";
 627   return name()->as_klass_external_name();
 628 }
 629 
 630 const char* Klass::signature_name() const {
 631   if (name() == NULL)  return "<unknown>";
 632   return name()->as_C_string();
 633 }
 634 
 635 const char* Klass::external_kind() const {
 636   if (is_interface()) return "interface";
 637   if (is_abstract()) return "abstract class";
 638   return "class";
 639 }
 640 
 641 // Unless overridden, modifier_flags is 0.
 642 jint Klass::compute_modifier_flags(TRAPS) const {
 643   return 0;
 644 }
 645 
 646 int Klass::atomic_incr_biased_lock_revocation_count() {
 647   return (int) Atomic::add(1, &_biased_lock_revocation_count);
 648 }
 649 
 650 // Unless overridden, jvmti_class_status has no flags set.
 651 jint Klass::jvmti_class_status() const {
 652   return 0;
 653 }
 654 
 655 
 656 // Printing
 657 
 658 void Klass::print_on(outputStream* st) const {
 659   ResourceMark rm;
 660   // print title
 661   st->print("%s", internal_name());
 662   print_address_on(st);
 663   st->cr();
 664 }
 665 
 666 void Klass::oop_print_on(oop obj, outputStream* st) {
 667   ResourceMark rm;
 668   // print title
 669   st->print_cr("%s ", internal_name());
 670   obj->print_address_on(st);
 671 
 672   if (WizardMode) {
 673      // print header
 674      obj->mark()->print_on(st);
 675   }
 676 
 677   // print class
 678   st->print(" - klass: ");
 679   obj->klass()->print_value_on(st);
 680   st->cr();
 681 }
 682 
 683 void Klass::oop_print_value_on(oop obj, outputStream* st) {
 684   // print title
 685   ResourceMark rm;              // Cannot print in debug mode without this
 686   st->print("%s", internal_name());
 687   obj->print_address_on(st);
 688 }
 689 
 690 #if INCLUDE_SERVICES
 691 // Size Statistics
 692 void Klass::collect_statistics(KlassSizeStats *sz) const {
 693   sz->_klass_bytes = sz->count(this);
 694   sz->_mirror_bytes = sz->count(java_mirror());
 695   sz->_secondary_supers_bytes = sz->count_array(secondary_supers());
 696 
 697   sz->_ro_bytes += sz->_secondary_supers_bytes;
 698   sz->_rw_bytes += sz->_klass_bytes + sz->_mirror_bytes;
 699 }
 700 #endif // INCLUDE_SERVICES
 701 
 702 // Verification
 703 
 704 void Klass::verify_on(outputStream* st) {
 705 
 706   // This can be expensive, but it is worth checking that this klass is actually
 707   // in the CLD graph but not in production.
 708   assert(Metaspace::contains((address)this), "Should be");
 709 
 710   guarantee(this->is_klass(),"should be klass");
 711 
 712   if (super() != NULL) {
 713     guarantee(super()->is_klass(), "should be klass");
 714   }
 715   if (secondary_super_cache() != NULL) {
 716     Klass* ko = secondary_super_cache();
 717     guarantee(ko->is_klass(), "should be klass");
 718   }
 719   for ( uint i = 0; i < primary_super_limit(); i++ ) {
 720     Klass* ko = _primary_supers[i];
 721     if (ko != NULL) {
 722       guarantee(ko->is_klass(), "should be klass");
 723     }
 724   }
 725 
 726   if (java_mirror() != NULL) {
 727     guarantee(oopDesc::is_oop(java_mirror()), "should be instance");
 728   }
 729 }
 730 
 731 void Klass::oop_verify_on(oop obj, outputStream* st) {
 732   guarantee(oopDesc::is_oop(obj),  "should be oop");
 733   guarantee(obj->klass()->is_klass(), "klass field is not a klass");
 734 }
 735 
 736 klassVtable Klass::vtable() const {
 737   return klassVtable(const_cast<Klass*>(this), start_of_vtable(), vtable_length() / vtableEntry::size());
 738 }
 739 
 740 vtableEntry* Klass::start_of_vtable() const {
 741   return (vtableEntry*) ((address)this + in_bytes(vtable_start_offset()));
 742 }
 743 
 744 Method* Klass::method_at_vtable(int index)  {
 745 #ifndef PRODUCT
 746   assert(index >= 0, "valid vtable index");
 747   if (DebugVtables) {
 748     verify_vtable_index(index);
 749   }
 750 #endif
 751   return start_of_vtable()[index].method();
 752 }
 753 
 754 ByteSize Klass::vtable_start_offset() {
 755   return in_ByteSize(InstanceKlass::header_size() * wordSize);
 756 }
 757 
 758 #ifndef PRODUCT
 759 
 760 bool Klass::verify_vtable_index(int i) {
 761   int limit = vtable_length()/vtableEntry::size();
 762   assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
 763   return true;
 764 }
 765 
 766 bool Klass::verify_itable_index(int i) {
 767   assert(is_instance_klass(), "");
 768   int method_count = klassItable::method_count_for_interface(this);
 769   assert(i >= 0 && i < method_count, "index out of bounds");
 770   return true;
 771 }
 772 
 773 #endif // PRODUCT
 774 
 775 // The caller of class_loader_and_module_name() (or one of its callers)
 776 // must use a ResourceMark in order to correctly free the result.
 777 const char* Klass::class_loader_and_module_name() const {
 778   const char* delim = "/";
 779   size_t delim_len = strlen(delim);
 780 
 781   const char* fqn = external_name();
 782   // Length of message to return; always include FQN
 783   size_t msglen = strlen(fqn) + 1;
 784 
 785   bool has_cl_name = false;
 786   bool has_mod_name = false;
 787   bool has_version = false;
 788 
 789   // Use class loader name, if exists and not builtin
 790   const char* class_loader_name = "";
 791   ClassLoaderData* cld = class_loader_data();
 792   assert(cld != NULL, "class_loader_data should not be NULL");
 793   if (!cld->is_builtin_class_loader_data()) {
 794     // If not builtin, look for name
 795     oop loader = class_loader();
 796     if (loader != NULL) {
 797       oop class_loader_name_oop = java_lang_ClassLoader::name(loader);
 798       if (class_loader_name_oop != NULL) {
 799         class_loader_name = java_lang_String::as_utf8_string(class_loader_name_oop);
 800         if (class_loader_name != NULL && class_loader_name[0] != '\0') {
 801           has_cl_name = true;
 802           msglen += strlen(class_loader_name) + delim_len;
 803         }
 804       }
 805     }
 806   }
 807 
 808   const char* module_name = "";
 809   const char* version = "";
 810   const Klass* bottom_klass = is_objArray_klass() ?
 811     ObjArrayKlass::cast(this)->bottom_klass() : this;
 812   if (bottom_klass->is_instance_klass()) {
 813     ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
 814     // Use module name, if exists
 815     if (module->is_named()) {
 816       has_mod_name = true;
 817       module_name = module->name()->as_C_string();
 818       msglen += strlen(module_name);
 819       // Use version if exists and is not a jdk module
 820       if (module->is_non_jdk_module() && module->version() != NULL) {
 821         has_version = true;
 822         version = module->version()->as_C_string();
 823         msglen += strlen("@") + strlen(version);
 824       }
 825     }
 826   } else {
 827     // klass is an array of primitives, so its module is java.base
 828     module_name = JAVA_BASE_NAME;
 829   }
 830 
 831   if (has_cl_name || has_mod_name) {
 832     msglen += delim_len;
 833   }
 834 
 835   char* message = NEW_RESOURCE_ARRAY_RETURN_NULL(char, msglen);
 836 
 837   // Just return the FQN if error in allocating string
 838   if (message == NULL) {
 839     return fqn;
 840   }
 841 
 842   jio_snprintf(message, msglen, "%s%s%s%s%s%s%s",
 843                class_loader_name,
 844                (has_cl_name) ? delim : "",
 845                (has_mod_name) ? module_name : "",
 846                (has_version) ? "@" : "",
 847                (has_version) ? version : "",
 848                (has_cl_name || has_mod_name) ? delim : "",
 849                fqn);
 850   return message;
 851 }