1 /*
   2  * Copyright (c) 1997, 2019, 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/classLoaderDataGraph.inline.hpp"
  28 #include "classfile/dictionary.hpp"
  29 #include "classfile/javaClasses.hpp"
  30 #include "classfile/moduleEntry.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "classfile/vmSymbols.hpp"
  33 #include "gc/shared/collectedHeap.inline.hpp"
  34 #include "logging/log.hpp"
  35 #include "memory/heapInspection.hpp"
  36 #include "memory/heapShared.hpp"
  37 #include "memory/metadataFactory.hpp"
  38 #include "memory/metaspaceClosure.hpp"
  39 #include "memory/metaspaceShared.hpp"
  40 #include "memory/oopFactory.hpp"
  41 #include "memory/resourceArea.hpp"
  42 #include "memory/universe.hpp"
  43 #include "oops/compressedOops.inline.hpp"
  44 #include "oops/instanceKlass.hpp"
  45 #include "oops/klass.inline.hpp"
  46 #include "oops/oop.inline.hpp"
  47 #include "oops/oopHandle.inline.hpp"
  48 #include "runtime/atomic.hpp"
  49 #include "runtime/handles.inline.hpp"
  50 #include "runtime/orderAccess.hpp"
  51 #include "utilities/macros.hpp"
  52 #include "utilities/stack.inline.hpp"
  53 
  54 void Klass::set_java_mirror(Handle m) {
  55   assert(!m.is_null(), "New mirror should never be null.");
  56   assert(_java_mirror.resolve() == NULL, "should only be used to initialize mirror");
  57   _java_mirror = class_loader_data()->add_handle(m);
  58 }
  59 
  60 oop Klass::java_mirror_no_keepalive() const {
  61   return _java_mirror.peek();
  62 }
  63 
  64 bool Klass::is_cloneable() const {
  65   return _access_flags.is_cloneable_fast() ||
  66          is_subtype_of(SystemDictionary::Cloneable_klass());
  67 }
  68 
  69 void Klass::set_is_cloneable() {
  70   if (name() == vmSymbols::java_lang_invoke_MemberName()) {
  71     assert(is_final(), "no subclasses allowed");
  72     // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
  73   } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
  74     // Reference cloning should not be intrinsified and always happen in JVM_Clone.
  75   } else {
  76     _access_flags.set_is_cloneable_fast();
  77   }
  78 }
  79 
  80 void Klass::set_name(Symbol* n) {
  81   _name = n;
  82   if (_name != NULL) _name->increment_refcount();
  83 }
  84 
  85 bool Klass::is_subclass_of(const Klass* k) const {
  86   // Run up the super chain and check
  87   if (this == k) return true;
  88 
  89   Klass* t = const_cast<Klass*>(this)->super();
  90 
  91   while (t != NULL) {
  92     if (t == k) return true;
  93     t = t->super();
  94   }
  95   return false;
  96 }
  97 
  98 bool Klass::search_secondary_supers(Klass* k) const {
  99   // Put some extra logic here out-of-line, before the search proper.
 100   // This cuts down the size of the inline method.
 101 
 102   // This is necessary, since I am never in my own secondary_super list.
 103   if (this == k)
 104     return true;
 105   // Scan the array-of-objects for a match
 106   int cnt = secondary_supers()->length();
 107   for (int i = 0; i < cnt; i++) {
 108     if (secondary_supers()->at(i) == k) {
 109       ((Klass*)this)->set_secondary_super_cache(k);
 110       return true;
 111     }
 112   }
 113   return false;
 114 }
 115 
 116 // Return self, except for abstract classes with exactly 1
 117 // implementor.  Then return the 1 concrete implementation.
 118 Klass *Klass::up_cast_abstract() {
 119   Klass *r = this;
 120   while( r->is_abstract() ) {   // Receiver is abstract?
 121     Klass *s = r->subklass();   // Check for exactly 1 subklass
 122     if (s == NULL || s->next_sibling() != NULL) // Oops; wrong count; give up
 123       return this;              // Return 'this' as a no-progress flag
 124     r = s;                    // Loop till find concrete class
 125   }
 126   return r;                   // Return the 1 concrete class
 127 }
 128 
 129 // Find LCA in class hierarchy
 130 Klass *Klass::LCA( Klass *k2 ) {
 131   Klass *k1 = this;
 132   while( 1 ) {
 133     if( k1->is_subtype_of(k2) ) return k2;
 134     if( k2->is_subtype_of(k1) ) return k1;
 135     k1 = k1->super();
 136     k2 = k2->super();
 137   }
 138 }
 139 
 140 
 141 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
 142   ResourceMark rm(THREAD);
 143   THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
 144             : vmSymbols::java_lang_InstantiationException(), external_name());
 145 }
 146 
 147 
 148 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
 149   ResourceMark rm(THREAD);
 150   assert(s != NULL, "Throw NPE!");
 151   THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
 152             err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
 153 }
 154 
 155 
 156 void Klass::initialize(TRAPS) {
 157   ShouldNotReachHere();
 158 }
 159 
 160 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
 161 #ifdef ASSERT
 162   tty->print_cr("Error: find_field called on a klass oop."
 163                 " Likely error: reflection method does not correctly"
 164                 " wrap return value in a mirror object.");
 165 #endif
 166   ShouldNotReachHere();
 167   return NULL;
 168 }
 169 
 170 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
 171                                       OverpassLookupMode overpass_mode,
 172                                       PrivateLookupMode private_mode) const {
 173 #ifdef ASSERT
 174   tty->print_cr("Error: uncached_lookup_method called on a klass oop."
 175                 " Likely error: reflection method does not correctly"
 176                 " wrap return value in a mirror object.");
 177 #endif
 178   ShouldNotReachHere();
 179   return NULL;
 180 }
 181 
 182 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
 183   return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
 184 }
 185 
 186 // "Normal" instantiation is preceeded by a MetaspaceObj allocation
 187 // which zeros out memory - calloc equivalent.
 188 // The constructor is also used from CppVtableCloner,
 189 // which doesn't zero out the memory before calling the constructor.
 190 // Need to set the _java_mirror field explicitly to not hit an assert that the field
 191 // should be NULL before setting it.
 192 Klass::Klass(KlassID id) : _id(id),
 193                            _java_mirror(NULL),
 194                            _prototype_header(markWord::prototype()),
 195                            _shared_class_path_index(-1) {
 196   CDS_ONLY(_shared_class_flags = 0;)
 197   CDS_JAVA_HEAP_ONLY(_archived_mirror = 0;)
 198   _primary_supers[0] = this;
 199   set_super_check_offset(in_bytes(primary_supers_offset()));
 200 }
 201 
 202 jint Klass::array_layout_helper(BasicType etype) {
 203   assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
 204   // Note that T_ARRAY is not allowed here.
 205   int  hsize = arrayOopDesc::base_offset_in_bytes(etype);
 206   int  esize = type2aelembytes(etype);
 207   bool isobj = (etype == T_OBJECT);
 208   int  tag   =  isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
 209   int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
 210 
 211   assert(lh < (int)_lh_neutral_value, "must look like an array layout");
 212   assert(layout_helper_is_array(lh), "correct kind");
 213   assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
 214   assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
 215   assert(layout_helper_header_size(lh) == hsize, "correct decode");
 216   assert(layout_helper_element_type(lh) == etype, "correct decode");
 217   assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
 218 
 219   return lh;
 220 }
 221 
 222 bool Klass::can_be_primary_super_slow() const {
 223   if (super() == NULL)
 224     return true;
 225   else if (super()->super_depth() >= primary_super_limit()-1)
 226     return false;
 227   else
 228     return true;
 229 }
 230 
 231 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
 232   if (k == NULL) {
 233     set_super(NULL);
 234     _primary_supers[0] = this;
 235     assert(super_depth() == 0, "Object must already be initialized properly");
 236   } else if (k != super() || k == SystemDictionary::Object_klass()) {
 237     assert(super() == NULL || super() == SystemDictionary::Object_klass(),
 238            "initialize this only once to a non-trivial value");
 239     set_super(k);
 240     Klass* sup = k;
 241     int sup_depth = sup->super_depth();
 242     juint my_depth  = MIN2(sup_depth + 1, (int)primary_super_limit());
 243     if (!can_be_primary_super_slow())
 244       my_depth = primary_super_limit();
 245     for (juint i = 0; i < my_depth; i++) {
 246       _primary_supers[i] = sup->_primary_supers[i];
 247     }
 248     Klass* *super_check_cell;
 249     if (my_depth < primary_super_limit()) {
 250       _primary_supers[my_depth] = this;
 251       super_check_cell = &_primary_supers[my_depth];
 252     } else {
 253       // Overflow of the primary_supers array forces me to be secondary.
 254       super_check_cell = &_secondary_super_cache;
 255     }
 256     set_super_check_offset((address)super_check_cell - (address) this);
 257 
 258 #ifdef ASSERT
 259     {
 260       juint j = super_depth();
 261       assert(j == my_depth, "computed accessor gets right answer");
 262       Klass* t = this;
 263       while (!t->can_be_primary_super()) {
 264         t = t->super();
 265         j = t->super_depth();
 266       }
 267       for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
 268         assert(primary_super_of_depth(j1) == NULL, "super list padding");
 269       }
 270       while (t != NULL) {
 271         assert(primary_super_of_depth(j) == t, "super list initialization");
 272         t = t->super();
 273         --j;
 274       }
 275       assert(j == (juint)-1, "correct depth count");
 276     }
 277 #endif
 278   }
 279 
 280   if (secondary_supers() == NULL) {
 281 
 282     // Now compute the list of secondary supertypes.
 283     // Secondaries can occasionally be on the super chain,
 284     // if the inline "_primary_supers" array overflows.
 285     int extras = 0;
 286     Klass* p;
 287     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
 288       ++extras;
 289     }
 290 
 291     ResourceMark rm(THREAD);  // need to reclaim GrowableArrays allocated below
 292 
 293     // Compute the "real" non-extra secondaries.
 294     GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
 295     if (secondaries == NULL) {
 296       // secondary_supers set by compute_secondary_supers
 297       return;
 298     }
 299 
 300     GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
 301 
 302     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
 303       int i;                    // Scan for overflow primaries being duplicates of 2nd'arys
 304 
 305       // This happens frequently for very deeply nested arrays: the
 306       // primary superclass chain overflows into the secondary.  The
 307       // secondary list contains the element_klass's secondaries with
 308       // an extra array dimension added.  If the element_klass's
 309       // secondary list already contains some primary overflows, they
 310       // (with the extra level of array-ness) will collide with the
 311       // normal primary superclass overflows.
 312       for( i = 0; i < secondaries->length(); i++ ) {
 313         if( secondaries->at(i) == p )
 314           break;
 315       }
 316       if( i < secondaries->length() )
 317         continue;               // It's a dup, don't put it in
 318       primaries->push(p);
 319     }
 320     // Combine the two arrays into a metadata object to pack the array.
 321     // The primaries are added in the reverse order, then the secondaries.
 322     int new_length = primaries->length() + secondaries->length();
 323     Array<Klass*>* s2 = MetadataFactory::new_array<Klass*>(
 324                                        class_loader_data(), new_length, CHECK);
 325     int fill_p = primaries->length();
 326     for (int j = 0; j < fill_p; j++) {
 327       s2->at_put(j, primaries->pop());  // add primaries in reverse order.
 328     }
 329     for( int j = 0; j < secondaries->length(); j++ ) {
 330       s2->at_put(j+fill_p, secondaries->at(j));  // add secondaries on the end.
 331     }
 332 
 333   #ifdef ASSERT
 334       // We must not copy any NULL placeholders left over from bootstrap.
 335     for (int j = 0; j < s2->length(); j++) {
 336       assert(s2->at(j) != NULL, "correct bootstrapping order");
 337     }
 338   #endif
 339 
 340     set_secondary_supers(s2);
 341   }
 342 }
 343 
 344 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
 345                                                        Array<InstanceKlass*>* transitive_interfaces) {
 346   assert(num_extra_slots == 0, "override for complex klasses");
 347   assert(transitive_interfaces == NULL, "sanity");
 348   set_secondary_supers(Universe::the_empty_klass_array());
 349   return NULL;
 350 }
 351 
 352 
 353 // superklass links
 354 InstanceKlass* Klass::superklass() const {
 355   assert(super() == NULL || super()->is_instance_klass(), "must be instance klass");
 356   return _super == NULL ? NULL : InstanceKlass::cast(_super);
 357 }
 358 
 359 // subklass links.  Used by the compiler (and vtable initialization)
 360 // May be cleaned concurrently, so must use the Compile_lock.
 361 // The log parameter is for clean_weak_klass_links to report unlinked classes.
 362 Klass* Klass::subklass(bool log) const {
 363   // Need load_acquire on the _subklass, because it races with inserts that
 364   // publishes freshly initialized data.
 365   for (Klass* chain = Atomic::load_acquire(&_subklass);
 366        chain != NULL;
 367        // Do not need load_acquire on _next_sibling, because inserts never
 368        // create _next_sibling edges to dead data.
 369        chain = Atomic::load(&chain->_next_sibling))
 370   {
 371     if (chain->is_loader_alive()) {
 372       return chain;
 373     } else if (log) {
 374       if (log_is_enabled(Trace, class, unload)) {
 375         ResourceMark rm;
 376         log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
 377       }
 378     }
 379   }
 380   return NULL;
 381 }
 382 
 383 Klass* Klass::next_sibling(bool log) const {
 384   // Do not need load_acquire on _next_sibling, because inserts never
 385   // create _next_sibling edges to dead data.
 386   for (Klass* chain = Atomic::load(&_next_sibling);
 387        chain != NULL;
 388        chain = Atomic::load(&chain->_next_sibling)) {
 389     // Only return alive klass, there may be stale klass
 390     // in this chain if cleaned concurrently.
 391     if (chain->is_loader_alive()) {
 392       return chain;
 393     } else if (log) {
 394       if (log_is_enabled(Trace, class, unload)) {
 395         ResourceMark rm;
 396         log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
 397       }
 398     }
 399   }
 400   return NULL;
 401 }
 402 
 403 void Klass::set_subklass(Klass* s) {
 404   assert(s != this, "sanity check");
 405   Atomic::release_store(&_subklass, s);
 406 }
 407 
 408 void Klass::set_next_sibling(Klass* s) {
 409   assert(s != this, "sanity check");
 410   // Does not need release semantics. If used by cleanup, it will link to
 411   // already safely published data, and if used by inserts, will be published
 412   // safely using cmpxchg.
 413   Atomic::store(&_next_sibling, s);
 414 }
 415 
 416 void Klass::append_to_sibling_list() {
 417   assert_locked_or_safepoint(Compile_lock);
 418   debug_only(verify();)
 419   // add ourselves to superklass' subklass list
 420   InstanceKlass* super = superklass();
 421   if (super == NULL) return;        // special case: class Object
 422   assert((!super->is_interface()    // interfaces cannot be supers
 423           && (super->superklass() == NULL || !is_interface())),
 424          "an interface can only be a subklass of Object");
 425 
 426   // Make sure there is no stale subklass head
 427   super->clean_subklass();
 428 
 429   for (;;) {
 430     Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
 431     if (prev_first_subklass != NULL) {
 432       // set our sibling to be the superklass' previous first subklass
 433       assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
 434       set_next_sibling(prev_first_subklass);
 435     }
 436     // Note that the prev_first_subklass is always alive, meaning no sibling_next links
 437     // are ever created to not alive klasses. This is an important invariant of the lock-free
 438     // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
 439     if (Atomic::cmpxchg(this, &super->_subklass, prev_first_subklass) == prev_first_subklass) {
 440       return;
 441     }
 442   }
 443   debug_only(verify();)
 444 }
 445 
 446 void Klass::clean_subklass() {
 447   for (;;) {
 448     // Need load_acquire, due to contending with concurrent inserts
 449     Klass* subklass = Atomic::load_acquire(&_subklass);
 450     if (subklass == NULL || subklass->is_loader_alive()) {
 451       return;
 452     }
 453     // Try to fix _subklass until it points at something not dead.
 454     Atomic::cmpxchg(subklass->next_sibling(), &_subklass, subklass);
 455   }
 456 }
 457 
 458 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
 459   if (!ClassUnloading || !unloading_occurred) {
 460     return;
 461   }
 462 
 463   Klass* root = SystemDictionary::Object_klass();
 464   Stack<Klass*, mtGC> stack;
 465 
 466   stack.push(root);
 467   while (!stack.is_empty()) {
 468     Klass* current = stack.pop();
 469 
 470     assert(current->is_loader_alive(), "just checking, this should be live");
 471 
 472     // Find and set the first alive subklass
 473     Klass* sub = current->subklass(true);
 474     current->clean_subklass();
 475     if (sub != NULL) {
 476       stack.push(sub);
 477     }
 478 
 479     // Find and set the first alive sibling
 480     Klass* sibling = current->next_sibling(true);
 481     current->set_next_sibling(sibling);
 482     if (sibling != NULL) {
 483       stack.push(sibling);
 484     }
 485 
 486     // Clean the implementors list and method data.
 487     if (clean_alive_klasses && current->is_instance_klass()) {
 488       InstanceKlass* ik = InstanceKlass::cast(current);
 489       ik->clean_weak_instanceklass_links();
 490 
 491       // JVMTI RedefineClasses creates previous versions that are not in
 492       // the class hierarchy, so process them here.
 493       while ((ik = ik->previous_versions()) != NULL) {
 494         ik->clean_weak_instanceklass_links();
 495       }
 496     }
 497   }
 498 }
 499 
 500 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
 501   if (log_is_enabled(Trace, cds)) {
 502     ResourceMark rm;
 503     log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
 504   }
 505 
 506   it->push(&_name);
 507   it->push(&_secondary_super_cache);
 508   it->push(&_secondary_supers);
 509   for (int i = 0; i < _primary_super_limit; i++) {
 510     it->push(&_primary_supers[i]);
 511   }
 512   it->push(&_super);
 513   it->push((Klass**)&_subklass);
 514   it->push((Klass**)&_next_sibling);
 515   it->push(&_next_link);
 516 
 517   vtableEntry* vt = start_of_vtable();
 518   for (int i=0; i<vtable_length(); i++) {
 519     it->push(vt[i].method_addr());
 520   }
 521 }
 522 
 523 void Klass::remove_unshareable_info() {
 524   assert (Arguments::is_dumping_archive(),
 525           "only called during CDS dump time");
 526   JFR_ONLY(REMOVE_ID(this);)
 527   if (log_is_enabled(Trace, cds, unshareable)) {
 528     ResourceMark rm;
 529     log_trace(cds, unshareable)("remove: %s", external_name());
 530   }
 531 
 532   set_subklass(NULL);
 533   set_next_sibling(NULL);
 534   set_next_link(NULL);
 535 
 536   // Null out class_loader_data because we don't share that yet.
 537   set_class_loader_data(NULL);
 538   set_is_shared();
 539 }
 540 
 541 void Klass::remove_java_mirror() {
 542   Arguments::assert_is_dumping_archive();
 543   if (log_is_enabled(Trace, cds, unshareable)) {
 544     ResourceMark rm;
 545     log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
 546   }
 547   // Just null out the mirror.  The class_loader_data() no longer exists.
 548   _java_mirror = NULL;
 549 }
 550 
 551 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
 552   assert(is_klass(), "ensure C++ vtable is restored");
 553   assert(is_shared(), "must be set");
 554   JFR_ONLY(RESTORE_ID(this);)
 555   if (log_is_enabled(Trace, cds, unshareable)) {
 556     ResourceMark rm;
 557     log_trace(cds, unshareable)("restore: %s", external_name());
 558   }
 559 
 560   // If an exception happened during CDS restore, some of these fields may already be
 561   // set.  We leave the class on the CLD list, even if incomplete so that we don't
 562   // modify the CLD list outside a safepoint.
 563   if (class_loader_data() == NULL) {
 564     // Restore class_loader_data to the null class loader data
 565     set_class_loader_data(loader_data);
 566 
 567     // Add to null class loader list first before creating the mirror
 568     // (same order as class file parsing)
 569     loader_data->add_class(this);
 570   }
 571 
 572   Handle loader(THREAD, loader_data->class_loader());
 573   ModuleEntry* module_entry = NULL;
 574   Klass* k = this;
 575   if (k->is_objArray_klass()) {
 576     k = ObjArrayKlass::cast(k)->bottom_klass();
 577   }
 578   // Obtain klass' module.
 579   if (k->is_instance_klass()) {
 580     InstanceKlass* ik = (InstanceKlass*) k;
 581     module_entry = ik->module();
 582   } else {
 583     module_entry = ModuleEntryTable::javabase_moduleEntry();
 584   }
 585   // Obtain java.lang.Module, if available
 586   Handle module_handle(THREAD, ((module_entry != NULL) ? module_entry->module() : (oop)NULL));
 587 
 588   if (this->has_raw_archived_mirror()) {
 589     ResourceMark rm;
 590     log_debug(cds, mirror)("%s has raw archived mirror", external_name());
 591     if (HeapShared::open_archive_heap_region_mapped()) {
 592       bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
 593                                                               protection_domain,
 594                                                               CHECK);
 595       if (present) {
 596         return;
 597       }
 598     }
 599 
 600     // No archived mirror data
 601     log_debug(cds, mirror)("No archived mirror data for %s", external_name());
 602     _java_mirror = NULL;
 603     this->clear_has_raw_archived_mirror();
 604   }
 605 
 606   // Only recreate it if not present.  A previous attempt to restore may have
 607   // gotten an OOM later but keep the mirror if it was created.
 608   if (java_mirror() == NULL) {
 609     log_trace(cds, mirror)("Recreate mirror for %s", external_name());
 610     java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, CHECK);
 611   }
 612 }
 613 
 614 #if INCLUDE_CDS_JAVA_HEAP
 615 // Used at CDS dump time to access the archived mirror. No GC barrier.
 616 oop Klass::archived_java_mirror_raw() {
 617   assert(has_raw_archived_mirror(), "must have raw archived mirror");
 618   return CompressedOops::decode(_archived_mirror);
 619 }
 620 
 621 narrowOop Klass::archived_java_mirror_raw_narrow() {
 622   assert(has_raw_archived_mirror(), "must have raw archived mirror");
 623   return _archived_mirror;
 624 }
 625 
 626 // No GC barrier
 627 void Klass::set_archived_java_mirror_raw(oop m) {
 628   assert(DumpSharedSpaces, "called only during runtime");
 629   _archived_mirror = CompressedOops::encode(m);
 630 }
 631 #endif // INCLUDE_CDS_JAVA_HEAP
 632 
 633 Klass* Klass::array_klass_or_null(int rank) {
 634   EXCEPTION_MARK;
 635   // No exception can be thrown by array_klass_impl when called with or_null == true.
 636   // (In anycase, the execption mark will fail if it do so)
 637   return array_klass_impl(true, rank, THREAD);
 638 }
 639 
 640 
 641 Klass* Klass::array_klass_or_null() {
 642   EXCEPTION_MARK;
 643   // No exception can be thrown by array_klass_impl when called with or_null == true.
 644   // (In anycase, the execption mark will fail if it do so)
 645   return array_klass_impl(true, THREAD);
 646 }
 647 
 648 
 649 Klass* Klass::array_klass_impl(bool or_null, int rank, TRAPS) {
 650   fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
 651   return NULL;
 652 }
 653 
 654 
 655 Klass* Klass::array_klass_impl(bool or_null, TRAPS) {
 656   fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
 657   return NULL;
 658 }
 659 
 660 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
 661   if (length > max_length) {
 662     if (!THREAD->in_retryable_allocation()) {
 663       report_java_out_of_memory("Requested array size exceeds VM limit");
 664       JvmtiExport::post_array_size_exhausted();
 665       THROW_OOP(Universe::out_of_memory_error_array_size());
 666     } else {
 667       THROW_OOP(Universe::out_of_memory_error_retry());
 668     }
 669   } else if (length < 0) {
 670     THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
 671   }
 672 }
 673 
 674 // In product mode, this function doesn't have virtual function calls so
 675 // there might be some performance advantage to handling InstanceKlass here.
 676 const char* Klass::external_name() const {
 677   if (is_instance_klass()) {
 678     const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
 679     if (ik->is_unsafe_anonymous()) {
 680       char addr_buf[20];
 681       jio_snprintf(addr_buf, 20, "/" INTPTR_FORMAT, p2i(ik));
 682       size_t addr_len = strlen(addr_buf);
 683       size_t name_len = name()->utf8_length();
 684       char*  result   = NEW_RESOURCE_ARRAY(char, name_len + addr_len + 1);
 685       name()->as_klass_external_name(result, (int) name_len + 1);
 686       assert(strlen(result) == name_len, "");
 687       strcpy(result + name_len, addr_buf);
 688       assert(strlen(result) == name_len + addr_len, "");
 689       return result;
 690     }
 691   }
 692   if (name() == NULL)  return "<unknown>";
 693   return name()->as_klass_external_name();
 694 }
 695 
 696 const char* Klass::signature_name() const {
 697   if (name() == NULL)  return "<unknown>";
 698   return name()->as_C_string();
 699 }
 700 
 701 const char* Klass::external_kind() const {
 702   if (is_interface()) return "interface";
 703   if (is_abstract()) return "abstract class";
 704   return "class";
 705 }
 706 
 707 // Unless overridden, modifier_flags is 0.
 708 jint Klass::compute_modifier_flags(TRAPS) const {
 709   return 0;
 710 }
 711 
 712 int Klass::atomic_incr_biased_lock_revocation_count() {
 713   return (int) Atomic::add(&_biased_lock_revocation_count, 1);
 714 }
 715 
 716 // Unless overridden, jvmti_class_status has no flags set.
 717 jint Klass::jvmti_class_status() const {
 718   return 0;
 719 }
 720 
 721 
 722 // Printing
 723 
 724 void Klass::print_on(outputStream* st) const {
 725   ResourceMark rm;
 726   // print title
 727   st->print("%s", internal_name());
 728   print_address_on(st);
 729   st->cr();
 730 }
 731 
 732 #define BULLET  " - "
 733 
 734 void Klass::oop_print_on(oop obj, outputStream* st) {
 735   // print title
 736   st->print_cr("%s ", internal_name());
 737   obj->print_address_on(st);
 738 
 739   if (WizardMode) {
 740      // print header
 741      obj->mark().print_on(st);
 742      st->cr();
 743      st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
 744      st->cr();
 745   }
 746 
 747   // print class
 748   st->print(BULLET"klass: ");
 749   obj->klass()->print_value_on(st);
 750   st->cr();
 751 }
 752 
 753 void Klass::oop_print_value_on(oop obj, outputStream* st) {
 754   // print title
 755   ResourceMark rm;              // Cannot print in debug mode without this
 756   st->print("%s", internal_name());
 757   obj->print_address_on(st);
 758 }
 759 
 760 #if INCLUDE_SERVICES
 761 // Size Statistics
 762 void Klass::collect_statistics(KlassSizeStats *sz) const {
 763   sz->_klass_bytes = sz->count(this);
 764   sz->_mirror_bytes = sz->count(java_mirror_no_keepalive());
 765   sz->_secondary_supers_bytes = sz->count_array(secondary_supers());
 766 
 767   sz->_ro_bytes += sz->_secondary_supers_bytes;
 768   sz->_rw_bytes += sz->_klass_bytes + sz->_mirror_bytes;
 769 }
 770 #endif // INCLUDE_SERVICES
 771 
 772 // Verification
 773 
 774 void Klass::verify_on(outputStream* st) {
 775 
 776   // This can be expensive, but it is worth checking that this klass is actually
 777   // in the CLD graph but not in production.
 778   assert(Metaspace::contains((address)this), "Should be");
 779 
 780   guarantee(this->is_klass(),"should be klass");
 781 
 782   if (super() != NULL) {
 783     guarantee(super()->is_klass(), "should be klass");
 784   }
 785   if (secondary_super_cache() != NULL) {
 786     Klass* ko = secondary_super_cache();
 787     guarantee(ko->is_klass(), "should be klass");
 788   }
 789   for ( uint i = 0; i < primary_super_limit(); i++ ) {
 790     Klass* ko = _primary_supers[i];
 791     if (ko != NULL) {
 792       guarantee(ko->is_klass(), "should be klass");
 793     }
 794   }
 795 
 796   if (java_mirror_no_keepalive() != NULL) {
 797     guarantee(oopDesc::is_oop(java_mirror_no_keepalive()), "should be instance");
 798   }
 799 }
 800 
 801 void Klass::oop_verify_on(oop obj, outputStream* st) {
 802   guarantee(oopDesc::is_oop(obj),  "should be oop");
 803   guarantee(obj->klass()->is_klass(), "klass field is not a klass");
 804 }
 805 
 806 bool Klass::is_valid(Klass* k) {
 807   if (!is_aligned(k, sizeof(MetaWord))) return false;
 808   if ((size_t)k < os::min_page_size()) return false;
 809 
 810   if (!os::is_readable_range(k, k + 1)) return false;
 811   if (!Metaspace::contains(k)) return false;
 812 
 813   if (!Symbol::is_valid(k->name())) return false;
 814   return ClassLoaderDataGraph::is_valid(k->class_loader_data());
 815 }
 816 
 817 Method* Klass::method_at_vtable(int index)  {
 818 #ifndef PRODUCT
 819   assert(index >= 0, "valid vtable index");
 820   if (DebugVtables) {
 821     verify_vtable_index(index);
 822   }
 823 #endif
 824   return start_of_vtable()[index].method();
 825 }
 826 
 827 
 828 #ifndef PRODUCT
 829 
 830 bool Klass::verify_vtable_index(int i) {
 831   int limit = vtable_length()/vtableEntry::size();
 832   assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
 833   return true;
 834 }
 835 
 836 #endif // PRODUCT
 837 
 838 // Caller needs ResourceMark
 839 // joint_in_module_of_loader provides an optimization if 2 classes are in
 840 // the same module to succinctly print out relevant information about their
 841 // module name and class loader's name_and_id for error messages.
 842 // Format:
 843 //   <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
 844 //                      are in module <module-name>[@<version>]
 845 //                      of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
 846 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
 847   assert(module() == class2->module(), "classes do not have the same module");
 848   const char* class1_name = external_name();
 849   size_t len = strlen(class1_name) + 1;
 850 
 851   const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
 852   len += strlen(class2_description);
 853 
 854   len += strlen(" and ");
 855 
 856   char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
 857 
 858   // Just return the FQN if error when allocating string
 859   if (joint_description == NULL) {
 860     return class1_name;
 861   }
 862 
 863   jio_snprintf(joint_description, len, "%s and %s",
 864                class1_name,
 865                class2_description);
 866 
 867   return joint_description;
 868 }
 869 
 870 // Caller needs ResourceMark
 871 // class_in_module_of_loader provides a standard way to include
 872 // relevant information about a class, such as its module name as
 873 // well as its class loader's name_and_id, in error messages and logging.
 874 // Format:
 875 //   <fully-qualified-external-class-name> is in module <module-name>[@<version>]
 876 //                                         of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
 877 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
 878   // 1. fully qualified external name of class
 879   const char* klass_name = external_name();
 880   size_t len = strlen(klass_name) + 1;
 881 
 882   // 2. module name + @version
 883   const char* module_name = "";
 884   const char* version = "";
 885   bool has_version = false;
 886   bool module_is_named = false;
 887   const char* module_name_phrase = "";
 888   const Klass* bottom_klass = is_objArray_klass() ?
 889                                 ObjArrayKlass::cast(this)->bottom_klass() : this;
 890   if (bottom_klass->is_instance_klass()) {
 891     ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
 892     if (module->is_named()) {
 893       module_is_named = true;
 894       module_name_phrase = "module ";
 895       module_name = module->name()->as_C_string();
 896       len += strlen(module_name);
 897       // Use version if exists and is not a jdk module
 898       if (module->should_show_version()) {
 899         has_version = true;
 900         version = module->version()->as_C_string();
 901         // Include stlen(version) + 1 for the "@"
 902         len += strlen(version) + 1;
 903       }
 904     } else {
 905       module_name = UNNAMED_MODULE;
 906       len += UNNAMED_MODULE_LEN;
 907     }
 908   } else {
 909     // klass is an array of primitives, module is java.base
 910     module_is_named = true;
 911     module_name_phrase = "module ";
 912     module_name = JAVA_BASE_NAME;
 913     len += JAVA_BASE_NAME_LEN;
 914   }
 915 
 916   // 3. class loader's name_and_id
 917   ClassLoaderData* cld = class_loader_data();
 918   assert(cld != NULL, "class_loader_data should not be null");
 919   const char* loader_name_and_id = cld->loader_name_and_id();
 920   len += strlen(loader_name_and_id);
 921 
 922   // 4. include parent loader information
 923   const char* parent_loader_phrase = "";
 924   const char* parent_loader_name_and_id = "";
 925   if (include_parent_loader &&
 926       !cld->is_builtin_class_loader_data()) {
 927     oop parent_loader = java_lang_ClassLoader::parent(class_loader());
 928     ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
 929     // The parent loader's ClassLoaderData could be null if it is
 930     // a delegating class loader that has never defined a class.
 931     // In this case the loader's name must be obtained via the parent loader's oop.
 932     if (parent_cld == NULL) {
 933       oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
 934       if (cl_name_and_id != NULL) {
 935         parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
 936       }
 937     } else {
 938       parent_loader_name_and_id = parent_cld->loader_name_and_id();
 939     }
 940     parent_loader_phrase = ", parent loader ";
 941     len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
 942   }
 943 
 944   // Start to construct final full class description string
 945   len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
 946   len += strlen(module_name_phrase) + strlen(" of loader ");
 947 
 948   char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
 949 
 950   // Just return the FQN if error when allocating string
 951   if (class_description == NULL) {
 952     return klass_name;
 953   }
 954 
 955   jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
 956                klass_name,
 957                (use_are) ? "are" : "is",
 958                module_name_phrase,
 959                module_name,
 960                (has_version) ? "@" : "",
 961                (has_version) ? version : "",
 962                loader_name_and_id,
 963                parent_loader_phrase,
 964                parent_loader_name_and_id);
 965 
 966   return class_description;
 967 }