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