1 /*
   2  * Copyright (c) 1997, 2020, 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/systemDictionaryShared.hpp"
  33 #include "classfile/vmSymbols.hpp"
  34 #include "gc/shared/collectedHeap.inline.hpp"
  35 #include "logging/log.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/arguments.hpp"
  49 #include "runtime/atomic.hpp"
  50 #include "runtime/handles.inline.hpp"
  51 #include "utilities/macros.hpp"
  52 #include "utilities/powerOfTwo.hpp"
  53 #include "utilities/stack.inline.hpp"
  54 
  55 void Klass::set_java_mirror(Handle m) {
  56   assert(!m.is_null(), "New mirror should never be null.");
  57   assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
  58   _java_mirror = class_loader_data()->add_handle(m);
  59 }
  60 
  61 oop Klass::java_mirror_no_keepalive() const {
  62   return _java_mirror.peek();
  63 }
  64 
  65 void Klass::replace_java_mirror(oop mirror) {
  66   _java_mirror.replace(mirror);
  67 }
  68 
  69 bool Klass::is_cloneable() const {
  70   return _access_flags.is_cloneable_fast() ||
  71          is_subtype_of(SystemDictionary::Cloneable_klass());
  72 }
  73 
  74 void Klass::set_is_cloneable() {
  75   if (name() == vmSymbols::java_lang_invoke_MemberName()) {
  76     assert(is_final(), "no subclasses allowed");
  77     // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
  78   } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
  79     // Reference cloning should not be intrinsified and always happen in JVM_Clone.
  80   } else {
  81     _access_flags.set_is_cloneable_fast();
  82   }
  83 }
  84 
  85 void Klass::set_name(Symbol* n) {
  86   _name = n;
  87   if (_name != NULL) _name->increment_refcount();
  88 
  89   if (Arguments::is_dumping_archive() && is_instance_klass()) {
  90     SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
  91   }
  92 }
  93 
  94 bool Klass::is_subclass_of(const Klass* k) const {
  95   // Run up the super chain and check
  96   if (this == k) return true;
  97 
  98   Klass* t = const_cast<Klass*>(this)->super();
  99 
 100   while (t != NULL) {
 101     if (t == k) return true;
 102     t = t->super();
 103   }
 104   return false;
 105 }
 106 
 107 void Klass::release_C_heap_structures() {
 108   if (_name != NULL) _name->decrement_refcount();
 109 }
 110 
 111 bool Klass::search_secondary_supers(Klass* k) const {
 112   // Put some extra logic here out-of-line, before the search proper.
 113   // This cuts down the size of the inline method.
 114 
 115   // This is necessary, since I am never in my own secondary_super list.
 116   if (this == k)
 117     return true;
 118   // Scan the array-of-objects for a match
 119   int cnt = secondary_supers()->length();
 120   for (int i = 0; i < cnt; i++) {
 121     if (secondary_supers()->at(i) == k) {
 122       ((Klass*)this)->set_secondary_super_cache(k);
 123       return true;
 124     }
 125   }
 126   return false;
 127 }
 128 
 129 // Return self, except for abstract classes with exactly 1
 130 // implementor.  Then return the 1 concrete implementation.
 131 Klass *Klass::up_cast_abstract() {
 132   Klass *r = this;
 133   while( r->is_abstract() ) {   // Receiver is abstract?
 134     Klass *s = r->subklass();   // Check for exactly 1 subklass
 135     if (s == NULL || s->next_sibling() != NULL) // Oops; wrong count; give up
 136       return this;              // Return 'this' as a no-progress flag
 137     r = s;                    // Loop till find concrete class
 138   }
 139   return r;                   // Return the 1 concrete class
 140 }
 141 
 142 // Find LCA in class hierarchy
 143 Klass *Klass::LCA( Klass *k2 ) {
 144   Klass *k1 = this;
 145   while( 1 ) {
 146     if( k1->is_subtype_of(k2) ) return k2;
 147     if( k2->is_subtype_of(k1) ) return k1;
 148     k1 = k1->super();
 149     k2 = k2->super();
 150   }
 151 }
 152 
 153 
 154 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
 155   ResourceMark rm(THREAD);
 156   THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
 157             : vmSymbols::java_lang_InstantiationException(), external_name());
 158 }
 159 
 160 
 161 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
 162   ResourceMark rm(THREAD);
 163   assert(s != NULL, "Throw NPE!");
 164   THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
 165             err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
 166 }
 167 
 168 
 169 void Klass::initialize(TRAPS) {
 170   ShouldNotReachHere();
 171 }
 172 
 173 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
 174 #ifdef ASSERT
 175   tty->print_cr("Error: find_field called on a klass oop."
 176                 " Likely error: reflection method does not correctly"
 177                 " wrap return value in a mirror object.");
 178 #endif
 179   ShouldNotReachHere();
 180   return NULL;
 181 }
 182 
 183 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
 184                                       OverpassLookupMode overpass_mode,
 185                                       PrivateLookupMode private_mode) const {
 186 #ifdef ASSERT
 187   tty->print_cr("Error: uncached_lookup_method called on a klass oop."
 188                 " Likely error: reflection method does not correctly"
 189                 " wrap return value in a mirror object.");
 190 #endif
 191   ShouldNotReachHere();
 192   return NULL;
 193 }
 194 
 195 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
 196   return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
 197 }
 198 
 199 // "Normal" instantiation is preceeded by a MetaspaceObj allocation
 200 // which zeros out memory - calloc equivalent.
 201 // The constructor is also used from CppVtableCloner,
 202 // which doesn't zero out the memory before calling the constructor.
 203 Klass::Klass(KlassID id) : _id(id),
 204                            _prototype_header(markWord::prototype()),
 205                            _shared_class_path_index(-1) {
 206   CDS_ONLY(_shared_class_flags = 0;)
 207   CDS_JAVA_HEAP_ONLY(_archived_mirror = narrowOop::null;)
 208   _primary_supers[0] = this;
 209   set_super_check_offset(in_bytes(primary_supers_offset()));
 210 }
 211 
 212 jint Klass::array_layout_helper(BasicType etype) {
 213   assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
 214   // Note that T_ARRAY is not allowed here.
 215   int  hsize = arrayOopDesc::base_offset_in_bytes(etype);
 216   int  esize = type2aelembytes(etype);
 217   bool isobj = (etype == T_OBJECT);
 218   int  tag   =  isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
 219   int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
 220 
 221   assert(lh < (int)_lh_neutral_value, "must look like an array layout");
 222   assert(layout_helper_is_array(lh), "correct kind");
 223   assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
 224   assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
 225   assert(layout_helper_header_size(lh) == hsize, "correct decode");
 226   assert(layout_helper_element_type(lh) == etype, "correct decode");
 227   assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
 228 
 229   return lh;
 230 }
 231 
 232 bool Klass::can_be_primary_super_slow() const {
 233   if (super() == NULL)
 234     return true;
 235   else if (super()->super_depth() >= primary_super_limit()-1)
 236     return false;
 237   else
 238     return true;
 239 }
 240 
 241 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
 242   if (k == NULL) {
 243     set_super(NULL);
 244     _primary_supers[0] = this;
 245     assert(super_depth() == 0, "Object must already be initialized properly");
 246   } else if (k != super() || k == SystemDictionary::Object_klass()) {
 247     assert(super() == NULL || super() == SystemDictionary::Object_klass(),
 248            "initialize this only once to a non-trivial value");
 249     set_super(k);
 250     Klass* sup = k;
 251     int sup_depth = sup->super_depth();
 252     juint my_depth  = MIN2(sup_depth + 1, (int)primary_super_limit());
 253     if (!can_be_primary_super_slow())
 254       my_depth = primary_super_limit();
 255     for (juint i = 0; i < my_depth; i++) {
 256       _primary_supers[i] = sup->_primary_supers[i];
 257     }
 258     Klass* *super_check_cell;
 259     if (my_depth < primary_super_limit()) {
 260       _primary_supers[my_depth] = this;
 261       super_check_cell = &_primary_supers[my_depth];
 262     } else {
 263       // Overflow of the primary_supers array forces me to be secondary.
 264       super_check_cell = &_secondary_super_cache;
 265     }
 266     set_super_check_offset((address)super_check_cell - (address) this);
 267 
 268 #ifdef ASSERT
 269     {
 270       juint j = super_depth();
 271       assert(j == my_depth, "computed accessor gets right answer");
 272       Klass* t = this;
 273       while (!t->can_be_primary_super()) {
 274         t = t->super();
 275         j = t->super_depth();
 276       }
 277       for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
 278         assert(primary_super_of_depth(j1) == NULL, "super list padding");
 279       }
 280       while (t != NULL) {
 281         assert(primary_super_of_depth(j) == t, "super list initialization");
 282         t = t->super();
 283         --j;
 284       }
 285       assert(j == (juint)-1, "correct depth count");
 286     }
 287 #endif
 288   }
 289 
 290   if (secondary_supers() == NULL) {
 291 
 292     // Now compute the list of secondary supertypes.
 293     // Secondaries can occasionally be on the super chain,
 294     // if the inline "_primary_supers" array overflows.
 295     int extras = 0;
 296     Klass* p;
 297     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
 298       ++extras;
 299     }
 300 
 301     ResourceMark rm(THREAD);  // need to reclaim GrowableArrays allocated below
 302 
 303     // Compute the "real" non-extra secondaries.
 304     GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
 305     if (secondaries == NULL) {
 306       // secondary_supers set by compute_secondary_supers
 307       return;
 308     }
 309 
 310     GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
 311 
 312     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
 313       int i;                    // Scan for overflow primaries being duplicates of 2nd'arys
 314 
 315       // This happens frequently for very deeply nested arrays: the
 316       // primary superclass chain overflows into the secondary.  The
 317       // secondary list contains the element_klass's secondaries with
 318       // an extra array dimension added.  If the element_klass's
 319       // secondary list already contains some primary overflows, they
 320       // (with the extra level of array-ness) will collide with the
 321       // normal primary superclass overflows.
 322       for( i = 0; i < secondaries->length(); i++ ) {
 323         if( secondaries->at(i) == p )
 324           break;
 325       }
 326       if( i < secondaries->length() )
 327         continue;               // It's a dup, don't put it in
 328       primaries->push(p);
 329     }
 330     // Combine the two arrays into a metadata object to pack the array.
 331     // The primaries are added in the reverse order, then the secondaries.
 332     int new_length = primaries->length() + secondaries->length();
 333     Array<Klass*>* s2 = MetadataFactory::new_array<Klass*>(
 334                                        class_loader_data(), new_length, CHECK);
 335     int fill_p = primaries->length();
 336     for (int j = 0; j < fill_p; j++) {
 337       s2->at_put(j, primaries->pop());  // add primaries in reverse order.
 338     }
 339     for( int j = 0; j < secondaries->length(); j++ ) {
 340       s2->at_put(j+fill_p, secondaries->at(j));  // add secondaries on the end.
 341     }
 342 
 343   #ifdef ASSERT
 344       // We must not copy any NULL placeholders left over from bootstrap.
 345     for (int j = 0; j < s2->length(); j++) {
 346       assert(s2->at(j) != NULL, "correct bootstrapping order");
 347     }
 348   #endif
 349 
 350     set_secondary_supers(s2);
 351   }
 352 }
 353 
 354 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
 355                                                        Array<InstanceKlass*>* transitive_interfaces) {
 356   assert(num_extra_slots == 0, "override for complex klasses");
 357   assert(transitive_interfaces == NULL, "sanity");
 358   set_secondary_supers(Universe::the_empty_klass_array());
 359   return NULL;
 360 }
 361 
 362 
 363 // superklass links
 364 InstanceKlass* Klass::superklass() const {
 365   assert(super() == NULL || super()->is_instance_klass(), "must be instance klass");
 366   return _super == NULL ? NULL : InstanceKlass::cast(_super);
 367 }
 368 
 369 // subklass links.  Used by the compiler (and vtable initialization)
 370 // May be cleaned concurrently, so must use the Compile_lock.
 371 // The log parameter is for clean_weak_klass_links to report unlinked classes.
 372 Klass* Klass::subklass(bool log) const {
 373   // Need load_acquire on the _subklass, because it races with inserts that
 374   // publishes freshly initialized data.
 375   for (Klass* chain = Atomic::load_acquire(&_subklass);
 376        chain != NULL;
 377        // Do not need load_acquire on _next_sibling, because inserts never
 378        // create _next_sibling edges to dead data.
 379        chain = Atomic::load(&chain->_next_sibling))
 380   {
 381     if (chain->is_loader_alive()) {
 382       return chain;
 383     } else if (log) {
 384       if (log_is_enabled(Trace, class, unload)) {
 385         ResourceMark rm;
 386         log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
 387       }
 388     }
 389   }
 390   return NULL;
 391 }
 392 
 393 Klass* Klass::next_sibling(bool log) const {
 394   // Do not need load_acquire on _next_sibling, because inserts never
 395   // create _next_sibling edges to dead data.
 396   for (Klass* chain = Atomic::load(&_next_sibling);
 397        chain != NULL;
 398        chain = Atomic::load(&chain->_next_sibling)) {
 399     // Only return alive klass, there may be stale klass
 400     // in this chain if cleaned concurrently.
 401     if (chain->is_loader_alive()) {
 402       return chain;
 403     } else if (log) {
 404       if (log_is_enabled(Trace, class, unload)) {
 405         ResourceMark rm;
 406         log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
 407       }
 408     }
 409   }
 410   return NULL;
 411 }
 412 
 413 void Klass::set_subklass(Klass* s) {
 414   assert(s != this, "sanity check");
 415   Atomic::release_store(&_subklass, s);
 416 }
 417 
 418 void Klass::set_next_sibling(Klass* s) {
 419   assert(s != this, "sanity check");
 420   // Does not need release semantics. If used by cleanup, it will link to
 421   // already safely published data, and if used by inserts, will be published
 422   // safely using cmpxchg.
 423   Atomic::store(&_next_sibling, s);
 424 }
 425 
 426 void Klass::append_to_sibling_list() {
 427   if (Universe::is_fully_initialized()) {
 428     assert_locked_or_safepoint(Compile_lock);
 429   }
 430   debug_only(verify();)
 431   // add ourselves to superklass' subklass list
 432   InstanceKlass* super = superklass();
 433   if (super == NULL) return;        // special case: class Object
 434   assert((!super->is_interface()    // interfaces cannot be supers
 435           && (super->superklass() == NULL || !is_interface())),
 436          "an interface can only be a subklass of Object");
 437 
 438   // Make sure there is no stale subklass head
 439   super->clean_subklass();
 440 
 441   for (;;) {
 442     Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
 443     if (prev_first_subklass != NULL) {
 444       // set our sibling to be the superklass' previous first subklass
 445       assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
 446       set_next_sibling(prev_first_subklass);
 447     }
 448     // Note that the prev_first_subklass is always alive, meaning no sibling_next links
 449     // are ever created to not alive klasses. This is an important invariant of the lock-free
 450     // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
 451     if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
 452       return;
 453     }
 454   }
 455   debug_only(verify();)
 456 }
 457 
 458 void Klass::clean_subklass() {
 459   for (;;) {
 460     // Need load_acquire, due to contending with concurrent inserts
 461     Klass* subklass = Atomic::load_acquire(&_subklass);
 462     if (subklass == NULL || subklass->is_loader_alive()) {
 463       return;
 464     }
 465     // Try to fix _subklass until it points at something not dead.
 466     Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
 467   }
 468 }
 469 
 470 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
 471   if (!ClassUnloading || !unloading_occurred) {
 472     return;
 473   }
 474 
 475   Klass* root = SystemDictionary::Object_klass();
 476   Stack<Klass*, mtGC> stack;
 477 
 478   stack.push(root);
 479   while (!stack.is_empty()) {
 480     Klass* current = stack.pop();
 481 
 482     assert(current->is_loader_alive(), "just checking, this should be live");
 483 
 484     // Find and set the first alive subklass
 485     Klass* sub = current->subklass(true);
 486     current->clean_subklass();
 487     if (sub != NULL) {
 488       stack.push(sub);
 489     }
 490 
 491     // Find and set the first alive sibling
 492     Klass* sibling = current->next_sibling(true);
 493     current->set_next_sibling(sibling);
 494     if (sibling != NULL) {
 495       stack.push(sibling);
 496     }
 497 
 498     // Clean the implementors list and method data.
 499     if (clean_alive_klasses && current->is_instance_klass()) {
 500       InstanceKlass* ik = InstanceKlass::cast(current);
 501       ik->clean_weak_instanceklass_links();
 502 
 503       // JVMTI RedefineClasses creates previous versions that are not in
 504       // the class hierarchy, so process them here.
 505       while ((ik = ik->previous_versions()) != NULL) {
 506         ik->clean_weak_instanceklass_links();
 507       }
 508     }
 509   }
 510 }
 511 
 512 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
 513   if (log_is_enabled(Trace, cds)) {
 514     ResourceMark rm;
 515     log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
 516   }
 517 
 518   it->push(&_name);
 519   it->push(&_secondary_super_cache);
 520   it->push(&_secondary_supers);
 521   for (int i = 0; i < _primary_super_limit; i++) {
 522     it->push(&_primary_supers[i]);
 523   }
 524   it->push(&_super);
 525   it->push((Klass**)&_subklass);
 526   it->push((Klass**)&_next_sibling);
 527   it->push(&_next_link);
 528 
 529   vtableEntry* vt = start_of_vtable();
 530   for (int i=0; i<vtable_length(); i++) {
 531     it->push(vt[i].method_addr());
 532   }
 533 }
 534 
 535 void Klass::remove_unshareable_info() {
 536   assert (Arguments::is_dumping_archive(),
 537           "only called during CDS dump time");
 538   JFR_ONLY(REMOVE_ID(this);)
 539   if (log_is_enabled(Trace, cds, unshareable)) {
 540     ResourceMark rm;
 541     log_trace(cds, unshareable)("remove: %s", external_name());
 542   }
 543 
 544   set_subklass(NULL);
 545   set_next_sibling(NULL);
 546   set_next_link(NULL);
 547 
 548   // Null out class_loader_data because we don't share that yet.
 549   set_class_loader_data(NULL);
 550   set_is_shared();
 551 }
 552 
 553 void Klass::remove_java_mirror() {
 554   Arguments::assert_is_dumping_archive();
 555   if (log_is_enabled(Trace, cds, unshareable)) {
 556     ResourceMark rm;
 557     log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
 558   }
 559   // Just null out the mirror.  The class_loader_data() no longer exists.
 560   clear_java_mirror_handle();
 561 }
 562 
 563 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
 564   assert(is_klass(), "ensure C++ vtable is restored");
 565   assert(is_shared(), "must be set");
 566   JFR_ONLY(RESTORE_ID(this);)
 567   if (log_is_enabled(Trace, cds, unshareable)) {
 568     ResourceMark rm(THREAD);
 569     log_trace(cds, unshareable)("restore: %s", external_name());
 570   }
 571 
 572   // If an exception happened during CDS restore, some of these fields may already be
 573   // set.  We leave the class on the CLD list, even if incomplete so that we don't
 574   // modify the CLD list outside a safepoint.
 575   if (class_loader_data() == NULL) {
 576     // Restore class_loader_data to the null class loader data
 577     set_class_loader_data(loader_data);
 578 
 579     // Add to null class loader list first before creating the mirror
 580     // (same order as class file parsing)
 581     loader_data->add_class(this);
 582   }
 583 
 584   Handle loader(THREAD, loader_data->class_loader());
 585   ModuleEntry* module_entry = NULL;
 586   Klass* k = this;
 587   if (k->is_objArray_klass()) {
 588     k = ObjArrayKlass::cast(k)->bottom_klass();
 589   }
 590   // Obtain klass' module.
 591   if (k->is_instance_klass()) {
 592     InstanceKlass* ik = (InstanceKlass*) k;
 593     module_entry = ik->module();
 594   } else {
 595     module_entry = ModuleEntryTable::javabase_moduleEntry();
 596   }
 597   // Obtain java.lang.Module, if available
 598   Handle module_handle(THREAD, ((module_entry != NULL) ? module_entry->module() : (oop)NULL));
 599 
 600   if (this->has_raw_archived_mirror()) {
 601     ResourceMark rm(THREAD);
 602     log_debug(cds, mirror)("%s has raw archived mirror", external_name());
 603     if (HeapShared::open_archive_heap_region_mapped()) {
 604       bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
 605                                                               protection_domain,
 606                                                               CHECK);
 607       if (present) {
 608         return;
 609       }
 610     }
 611 
 612     // No archived mirror data
 613     log_debug(cds, mirror)("No archived mirror data for %s", external_name());
 614     clear_java_mirror_handle();
 615     this->clear_has_raw_archived_mirror();
 616   }
 617 
 618   // Only recreate it if not present.  A previous attempt to restore may have
 619   // gotten an OOM later but keep the mirror if it was created.
 620   if (java_mirror() == NULL) {
 621     log_trace(cds, mirror)("Recreate mirror for %s", external_name());
 622     java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
 623   }
 624 }
 625 
 626 #if INCLUDE_CDS_JAVA_HEAP
 627 // Used at CDS dump time to access the archived mirror. No GC barrier.
 628 oop Klass::archived_java_mirror_raw() {
 629   assert(has_raw_archived_mirror(), "must have raw archived mirror");
 630   return CompressedOops::decode(_archived_mirror);
 631 }
 632 
 633 narrowOop Klass::archived_java_mirror_raw_narrow() {
 634   assert(has_raw_archived_mirror(), "must have raw archived mirror");
 635   return _archived_mirror;
 636 }
 637 
 638 // No GC barrier
 639 void Klass::set_archived_java_mirror_raw(oop m) {
 640   assert(DumpSharedSpaces, "called only during runtime");
 641   _archived_mirror = CompressedOops::encode(m);
 642 }
 643 #endif // INCLUDE_CDS_JAVA_HEAP
 644 
 645 Klass* Klass::array_klass_or_null(int rank) {
 646   EXCEPTION_MARK;
 647   // No exception can be thrown by array_klass_impl when called with or_null == true.
 648   // (In anycase, the execption mark will fail if it do so)
 649   return array_klass_impl(true, rank, THREAD);
 650 }
 651 
 652 
 653 Klass* Klass::array_klass_or_null() {
 654   EXCEPTION_MARK;
 655   // No exception can be thrown by array_klass_impl when called with or_null == true.
 656   // (In anycase, the execption mark will fail if it do so)
 657   return array_klass_impl(true, THREAD);
 658 }
 659 
 660 
 661 Klass* Klass::array_klass_impl(bool or_null, int rank, TRAPS) {
 662   fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
 663   return NULL;
 664 }
 665 
 666 
 667 Klass* Klass::array_klass_impl(bool or_null, TRAPS) {
 668   fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass");
 669   return NULL;
 670 }
 671 
 672 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
 673   if (length > max_length) {
 674     if (!THREAD->in_retryable_allocation()) {
 675       report_java_out_of_memory("Requested array size exceeds VM limit");
 676       JvmtiExport::post_array_size_exhausted();
 677       THROW_OOP(Universe::out_of_memory_error_array_size());
 678     } else {
 679       THROW_OOP(Universe::out_of_memory_error_retry());
 680     }
 681   } else if (length < 0) {
 682     THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
 683   }
 684 }
 685 
 686 // Replace the last '+' char with '/'.
 687 static char* convert_hidden_name_to_java(Symbol* name) {
 688   size_t name_len = name->utf8_length();
 689   char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
 690   name->as_klass_external_name(result, (int)name_len + 1);
 691   for (int index = (int)name_len; index > 0; index--) {
 692     if (result[index] == '+') {
 693       result[index] = JVM_SIGNATURE_SLASH;
 694       break;
 695     }
 696   }
 697   return result;
 698 }
 699 
 700 // In product mode, this function doesn't have virtual function calls so
 701 // there might be some performance advantage to handling InstanceKlass here.
 702 const char* Klass::external_name() const {
 703   if (is_instance_klass()) {
 704     const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
 705     if (ik->is_unsafe_anonymous()) {
 706       char addr_buf[20];
 707       jio_snprintf(addr_buf, 20, "/" INTPTR_FORMAT, p2i(ik));
 708       size_t addr_len = strlen(addr_buf);
 709       size_t name_len = name()->utf8_length();
 710       char*  result   = NEW_RESOURCE_ARRAY(char, name_len + addr_len + 1);
 711       name()->as_klass_external_name(result, (int) name_len + 1);
 712       assert(strlen(result) == name_len, "");
 713       strcpy(result + name_len, addr_buf);
 714       assert(strlen(result) == name_len + addr_len, "");
 715       return result;
 716 
 717     } else if (ik->is_hidden()) {
 718       char* result = convert_hidden_name_to_java(name());
 719       return result;
 720     }
 721   } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
 722     char* result = convert_hidden_name_to_java(name());
 723     return result;
 724   }
 725   if (name() == NULL)  return "<unknown>";
 726   return name()->as_klass_external_name();
 727 }
 728 
 729 const char* Klass::signature_name() const {
 730   if (name() == NULL)  return "<unknown>";
 731   if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
 732     size_t name_len = name()->utf8_length();
 733     char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
 734     name()->as_C_string(result, (int)name_len + 1);
 735     for (int index = (int)name_len; index > 0; index--) {
 736       if (result[index] == '+') {
 737         result[index] = JVM_SIGNATURE_DOT;
 738         break;
 739       }
 740     }
 741     return result;
 742   }
 743   return name()->as_C_string();
 744 }
 745 
 746 const char* Klass::external_kind() const {
 747   if (is_interface()) return "interface";
 748   if (is_abstract()) return "abstract class";
 749   return "class";
 750 }
 751 
 752 // Unless overridden, modifier_flags is 0.
 753 jint Klass::compute_modifier_flags(TRAPS) const {
 754   return 0;
 755 }
 756 
 757 int Klass::atomic_incr_biased_lock_revocation_count() {
 758   return (int) Atomic::add(&_biased_lock_revocation_count, 1);
 759 }
 760 
 761 // Unless overridden, jvmti_class_status has no flags set.
 762 jint Klass::jvmti_class_status() const {
 763   return 0;
 764 }
 765 
 766 
 767 // Printing
 768 
 769 void Klass::print_on(outputStream* st) const {
 770   ResourceMark rm;
 771   // print title
 772   st->print("%s", internal_name());
 773   print_address_on(st);
 774   st->cr();
 775 }
 776 
 777 #define BULLET  " - "
 778 
 779 // Caller needs ResourceMark
 780 void Klass::oop_print_on(oop obj, outputStream* st) {
 781   // print title
 782   st->print_cr("%s ", internal_name());
 783   obj->print_address_on(st);
 784 
 785   if (WizardMode) {
 786      // print header
 787      obj->mark().print_on(st);
 788      st->cr();
 789      st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
 790      st->cr();
 791   }
 792 
 793   // print class
 794   st->print(BULLET"klass: ");
 795   obj->klass()->print_value_on(st);
 796   st->cr();
 797 }
 798 
 799 void Klass::oop_print_value_on(oop obj, outputStream* st) {
 800   // print title
 801   ResourceMark rm;              // Cannot print in debug mode without this
 802   st->print("%s", internal_name());
 803   obj->print_address_on(st);
 804 }
 805 
 806 // Verification
 807 
 808 void Klass::verify_on(outputStream* st) {
 809 
 810   // This can be expensive, but it is worth checking that this klass is actually
 811   // in the CLD graph but not in production.
 812   assert(Metaspace::contains((address)this), "Should be");
 813 
 814   guarantee(this->is_klass(),"should be klass");
 815 
 816   if (super() != NULL) {
 817     guarantee(super()->is_klass(), "should be klass");
 818   }
 819   if (secondary_super_cache() != NULL) {
 820     Klass* ko = secondary_super_cache();
 821     guarantee(ko->is_klass(), "should be klass");
 822   }
 823   for ( uint i = 0; i < primary_super_limit(); i++ ) {
 824     Klass* ko = _primary_supers[i];
 825     if (ko != NULL) {
 826       guarantee(ko->is_klass(), "should be klass");
 827     }
 828   }
 829 
 830   if (java_mirror_no_keepalive() != NULL) {
 831     guarantee(oopDesc::is_oop(java_mirror_no_keepalive()), "should be instance");
 832   }
 833 }
 834 
 835 void Klass::oop_verify_on(oop obj, outputStream* st) {
 836   guarantee(oopDesc::is_oop(obj),  "should be oop");
 837   guarantee(obj->klass()->is_klass(), "klass field is not a klass");
 838 }
 839 
 840 bool Klass::is_valid(Klass* k) {
 841   if (!is_aligned(k, sizeof(MetaWord))) return false;
 842   if ((size_t)k < os::min_page_size()) return false;
 843 
 844   if (!os::is_readable_range(k, k + 1)) return false;
 845   if (!Metaspace::contains(k)) return false;
 846 
 847   if (!Symbol::is_valid(k->name())) return false;
 848   return ClassLoaderDataGraph::is_valid(k->class_loader_data());
 849 }
 850 
 851 Method* Klass::method_at_vtable(int index)  {
 852 #ifndef PRODUCT
 853   assert(index >= 0, "valid vtable index");
 854   if (DebugVtables) {
 855     verify_vtable_index(index);
 856   }
 857 #endif
 858   return start_of_vtable()[index].method();
 859 }
 860 
 861 
 862 #ifndef PRODUCT
 863 
 864 bool Klass::verify_vtable_index(int i) {
 865   int limit = vtable_length()/vtableEntry::size();
 866   assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
 867   return true;
 868 }
 869 
 870 #endif // PRODUCT
 871 
 872 // Caller needs ResourceMark
 873 // joint_in_module_of_loader provides an optimization if 2 classes are in
 874 // the same module to succinctly print out relevant information about their
 875 // module name and class loader's name_and_id for error messages.
 876 // Format:
 877 //   <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
 878 //                      are in module <module-name>[@<version>]
 879 //                      of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
 880 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
 881   assert(module() == class2->module(), "classes do not have the same module");
 882   const char* class1_name = external_name();
 883   size_t len = strlen(class1_name) + 1;
 884 
 885   const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
 886   len += strlen(class2_description);
 887 
 888   len += strlen(" and ");
 889 
 890   char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
 891 
 892   // Just return the FQN if error when allocating string
 893   if (joint_description == NULL) {
 894     return class1_name;
 895   }
 896 
 897   jio_snprintf(joint_description, len, "%s and %s",
 898                class1_name,
 899                class2_description);
 900 
 901   return joint_description;
 902 }
 903 
 904 // Caller needs ResourceMark
 905 // class_in_module_of_loader provides a standard way to include
 906 // relevant information about a class, such as its module name as
 907 // well as its class loader's name_and_id, in error messages and logging.
 908 // Format:
 909 //   <fully-qualified-external-class-name> is in module <module-name>[@<version>]
 910 //                                         of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
 911 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
 912   // 1. fully qualified external name of class
 913   const char* klass_name = external_name();
 914   size_t len = strlen(klass_name) + 1;
 915 
 916   // 2. module name + @version
 917   const char* module_name = "";
 918   const char* version = "";
 919   bool has_version = false;
 920   bool module_is_named = false;
 921   const char* module_name_phrase = "";
 922   const Klass* bottom_klass = is_objArray_klass() ?
 923                                 ObjArrayKlass::cast(this)->bottom_klass() : this;
 924   if (bottom_klass->is_instance_klass()) {
 925     ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
 926     if (module->is_named()) {
 927       module_is_named = true;
 928       module_name_phrase = "module ";
 929       module_name = module->name()->as_C_string();
 930       len += strlen(module_name);
 931       // Use version if exists and is not a jdk module
 932       if (module->should_show_version()) {
 933         has_version = true;
 934         version = module->version()->as_C_string();
 935         // Include stlen(version) + 1 for the "@"
 936         len += strlen(version) + 1;
 937       }
 938     } else {
 939       module_name = UNNAMED_MODULE;
 940       len += UNNAMED_MODULE_LEN;
 941     }
 942   } else {
 943     // klass is an array of primitives, module is java.base
 944     module_is_named = true;
 945     module_name_phrase = "module ";
 946     module_name = JAVA_BASE_NAME;
 947     len += JAVA_BASE_NAME_LEN;
 948   }
 949 
 950   // 3. class loader's name_and_id
 951   ClassLoaderData* cld = class_loader_data();
 952   assert(cld != NULL, "class_loader_data should not be null");
 953   const char* loader_name_and_id = cld->loader_name_and_id();
 954   len += strlen(loader_name_and_id);
 955 
 956   // 4. include parent loader information
 957   const char* parent_loader_phrase = "";
 958   const char* parent_loader_name_and_id = "";
 959   if (include_parent_loader &&
 960       !cld->is_builtin_class_loader_data()) {
 961     oop parent_loader = java_lang_ClassLoader::parent(class_loader());
 962     ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
 963     // The parent loader's ClassLoaderData could be null if it is
 964     // a delegating class loader that has never defined a class.
 965     // In this case the loader's name must be obtained via the parent loader's oop.
 966     if (parent_cld == NULL) {
 967       oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
 968       if (cl_name_and_id != NULL) {
 969         parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
 970       }
 971     } else {
 972       parent_loader_name_and_id = parent_cld->loader_name_and_id();
 973     }
 974     parent_loader_phrase = ", parent loader ";
 975     len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
 976   }
 977 
 978   // Start to construct final full class description string
 979   len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
 980   len += strlen(module_name_phrase) + strlen(" of loader ");
 981 
 982   char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
 983 
 984   // Just return the FQN if error when allocating string
 985   if (class_description == NULL) {
 986     return klass_name;
 987   }
 988 
 989   jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
 990                klass_name,
 991                (use_are) ? "are" : "is",
 992                module_name_phrase,
 993                module_name,
 994                (has_version) ? "@" : "",
 995                (has_version) ? version : "",
 996                loader_name_and_id,
 997                parent_loader_phrase,
 998                parent_loader_name_and_id);
 999 
1000   return class_description;
1001 }