1 /*
  2  * Copyright (c) 1997, 2022, 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 "cds/archiveHeapLoader.hpp"
 27 #include "cds/heapShared.hpp"
 28 #include "classfile/classLoaderData.inline.hpp"
 29 #include "classfile/classLoaderDataGraph.inline.hpp"
 30 #include "classfile/javaClasses.inline.hpp"
 31 #include "classfile/moduleEntry.hpp"
 32 #include "classfile/systemDictionary.hpp"
 33 #include "classfile/systemDictionaryShared.hpp"
 34 #include "classfile/vmClasses.hpp"
 35 #include "classfile/vmSymbols.hpp"
 36 #include "gc/shared/collectedHeap.inline.hpp"
 37 #include "jvm_io.h"
 38 #include "logging/log.hpp"
 39 #include "memory/metadataFactory.hpp"
 40 #include "memory/metaspaceClosure.hpp"
 41 #include "memory/oopFactory.hpp"
 42 #include "memory/resourceArea.hpp"
 43 #include "memory/universe.hpp"
 44 #include "oops/compressedOops.inline.hpp"
 45 #include "oops/instanceKlass.hpp"
 46 #include "oops/klass.inline.hpp"
 47 #include "oops/objArrayKlass.hpp"
 48 #include "oops/oop.inline.hpp"
 49 #include "oops/oopHandle.inline.hpp"
 50 #include "prims/jvmtiExport.hpp"
 51 #include "runtime/arguments.hpp"
 52 #include "runtime/atomic.hpp"
 53 #include "runtime/handles.inline.hpp"
 54 #include "utilities/macros.hpp"
 55 #include "utilities/powerOfTwo.hpp"
 56 #include "utilities/stack.inline.hpp"
 57 
 58 void Klass::set_java_mirror(Handle m) {
 59   assert(!m.is_null(), "New mirror should never be null.");
 60   assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
 61   _java_mirror = class_loader_data()->add_handle(m);
 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(vmClasses::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   if (Arguments::is_dumping_archive() && is_instance_klass()) {
 89     SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
 90   }
 91 }
 92 
 93 bool Klass::is_subclass_of(const Klass* k) const {
 94   // Run up the super chain and check
 95   if (this == k) return true;
 96 
 97   Klass* t = const_cast<Klass*>(this)->super();
 98 
 99   while (t != NULL) {
100     if (t == k) return true;
101     t = t->super();
102   }
103   return false;
104 }
105 
106 void Klass::release_C_heap_structures(bool release_constant_pool) {
107   if (_name != NULL) _name->decrement_refcount();
108 }
109 
110 bool Klass::search_secondary_supers(Klass* k) const {
111   // Put some extra logic here out-of-line, before the search proper.
112   // This cuts down the size of the inline method.
113 
114   // This is necessary, since I am never in my own secondary_super list.
115   if (this == k)
116     return true;
117   // Scan the array-of-objects for a match
118   int cnt = secondary_supers()->length();
119   for (int i = 0; i < cnt; i++) {
120     if (secondary_supers()->at(i) == k) {
121       ((Klass*)this)->set_secondary_super_cache(k);
122       return true;
123     }
124   }
125   return false;
126 }
127 
128 // Return self, except for abstract classes with exactly 1
129 // implementor.  Then return the 1 concrete implementation.
130 Klass *Klass::up_cast_abstract() {
131   Klass *r = this;
132   while( r->is_abstract() ) {   // Receiver is abstract?
133     Klass *s = r->subklass();   // Check for exactly 1 subklass
134     if (s == NULL || s->next_sibling() != NULL) // Oops; wrong count; give up
135       return this;              // Return 'this' as a no-progress flag
136     r = s;                    // Loop till find concrete class
137   }
138   return r;                   // Return the 1 concrete class
139 }
140 
141 // Find LCA in class hierarchy
142 Klass *Klass::LCA( Klass *k2 ) {
143   Klass *k1 = this;
144   while( 1 ) {
145     if( k1->is_subtype_of(k2) ) return k2;
146     if( k2->is_subtype_of(k1) ) return k1;
147     k1 = k1->super();
148     k2 = k2->super();
149   }
150 }
151 
152 
153 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
154   ResourceMark rm(THREAD);
155   THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
156             : vmSymbols::java_lang_InstantiationException(), external_name());
157 }
158 
159 
160 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
161   ResourceMark rm(THREAD);
162   assert(s != NULL, "Throw NPE!");
163   THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
164             err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
165 }
166 
167 
168 void Klass::initialize(TRAPS) {
169   ShouldNotReachHere();
170 }
171 
172 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
173 #ifdef ASSERT
174   tty->print_cr("Error: find_field 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 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
183                                       OverpassLookupMode overpass_mode,
184                                       PrivateLookupMode private_mode) const {
185 #ifdef ASSERT
186   tty->print_cr("Error: uncached_lookup_method called on a klass oop."
187                 " Likely error: reflection method does not correctly"
188                 " wrap return value in a mirror object.");
189 #endif
190   ShouldNotReachHere();
191   return NULL;
192 }
193 
194 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
195   return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
196 }
197 
198 // "Normal" instantiation is preceded by a MetaspaceObj allocation
199 // which zeros out memory - calloc equivalent.
200 // The constructor is also used from CppVtableCloner,
201 // which doesn't zero out the memory before calling the constructor.
202 Klass::Klass(KlassKind kind) : _kind(kind),
203                                _prototype_header(markWord::prototype()),
204                                _shared_class_path_index(-1) {
205   CDS_ONLY(_shared_class_flags = 0;)
206   CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
207   _primary_supers[0] = this;
208   set_super_check_offset(in_bytes(primary_supers_offset()));
209 }
210 
211 jint Klass::array_layout_helper(BasicType etype) {
212   assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
213   // Note that T_ARRAY is not allowed here.
214   int  hsize = arrayOopDesc::base_offset_in_bytes(etype);
215   int  esize = type2aelembytes(etype);
216   bool isobj = (etype == T_OBJECT);
217   int  tag   =  isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
218   int lh = array_layout_helper(tag, false, hsize, etype, exact_log2(esize));
219 
220   assert(lh < (int)_lh_neutral_value, "must look like an array layout");
221   assert(layout_helper_is_array(lh), "correct kind");
222   assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
223   assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
224   assert(layout_helper_header_size(lh) == hsize, "correct decode");
225   assert(layout_helper_element_type(lh) == etype, "correct decode");
226   assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
227 
228   return lh;
229 }
230 
231 bool Klass::can_be_primary_super_slow() const {
232   if (super() == NULL)
233     return true;
234   else if (super()->super_depth() >= primary_super_limit()-1)
235     return false;
236   else
237     return true;
238 }
239 
240 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
241   if (k == NULL) {
242     set_super(NULL);
243     _primary_supers[0] = this;
244     assert(super_depth() == 0, "Object must already be initialized properly");
245   } else if (k != super() || k == vmClasses::Object_klass()) {
246     assert(super() == NULL || super() == vmClasses::Object_klass(),
247            "initialize this only once to a non-trivial value");
248     set_super(k);
249     Klass* sup = k;
250     int sup_depth = sup->super_depth();
251     juint my_depth  = MIN2(sup_depth + 1, (int)primary_super_limit());
252     if (!can_be_primary_super_slow())
253       my_depth = primary_super_limit();
254     for (juint i = 0; i < my_depth; i++) {
255       _primary_supers[i] = sup->_primary_supers[i];
256     }
257     Klass* *super_check_cell;
258     if (my_depth < primary_super_limit()) {
259       _primary_supers[my_depth] = this;
260       super_check_cell = &_primary_supers[my_depth];
261     } else {
262       // Overflow of the primary_supers array forces me to be secondary.
263       super_check_cell = &_secondary_super_cache;
264     }
265     set_super_check_offset((address)super_check_cell - (address) this);
266 
267 #ifdef ASSERT
268     {
269       juint j = super_depth();
270       assert(j == my_depth, "computed accessor gets right answer");
271       Klass* t = this;
272       while (!t->can_be_primary_super()) {
273         t = t->super();
274         j = t->super_depth();
275       }
276       for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
277         assert(primary_super_of_depth(j1) == NULL, "super list padding");
278       }
279       while (t != NULL) {
280         assert(primary_super_of_depth(j) == t, "super list initialization");
281         t = t->super();
282         --j;
283       }
284       assert(j == (juint)-1, "correct depth count");
285     }
286 #endif
287   }
288 
289   if (secondary_supers() == NULL) {
290 
291     // Now compute the list of secondary supertypes.
292     // Secondaries can occasionally be on the super chain,
293     // if the inline "_primary_supers" array overflows.
294     int extras = 0;
295     Klass* p;
296     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
297       ++extras;
298     }
299 
300     ResourceMark rm(THREAD);  // need to reclaim GrowableArrays allocated below
301 
302     // Compute the "real" non-extra secondaries.
303     GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
304     if (secondaries == NULL) {
305       // secondary_supers set by compute_secondary_supers
306       return;
307     }
308 
309     GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
310 
311     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
312       int i;                    // Scan for overflow primaries being duplicates of 2nd'arys
313 
314       // This happens frequently for very deeply nested arrays: the
315       // primary superclass chain overflows into the secondary.  The
316       // secondary list contains the element_klass's secondaries with
317       // an extra array dimension added.  If the element_klass's
318       // secondary list already contains some primary overflows, they
319       // (with the extra level of array-ness) will collide with the
320       // normal primary superclass overflows.
321       for( i = 0; i < secondaries->length(); i++ ) {
322         if( secondaries->at(i) == p )
323           break;
324       }
325       if( i < secondaries->length() )
326         continue;               // It's a dup, don't put it in
327       primaries->push(p);
328     }
329     // Combine the two arrays into a metadata object to pack the array.
330     // The primaries are added in the reverse order, then the secondaries.
331     int new_length = primaries->length() + secondaries->length();
332     Array<Klass*>* s2 = MetadataFactory::new_array<Klass*>(
333                                        class_loader_data(), new_length, CHECK);
334     int fill_p = primaries->length();
335     for (int j = 0; j < fill_p; j++) {
336       s2->at_put(j, primaries->pop());  // add primaries in reverse order.
337     }
338     for( int j = 0; j < secondaries->length(); j++ ) {
339       s2->at_put(j+fill_p, secondaries->at(j));  // add secondaries on the end.
340     }
341 
342   #ifdef ASSERT
343       // We must not copy any NULL placeholders left over from bootstrap.
344     for (int j = 0; j < s2->length(); j++) {
345       assert(s2->at(j) != NULL, "correct bootstrapping order");
346     }
347   #endif
348 
349     set_secondary_supers(s2);
350   }
351 }
352 
353 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
354                                                        Array<InstanceKlass*>* transitive_interfaces) {
355   assert(num_extra_slots == 0, "override for complex klasses");
356   assert(transitive_interfaces == NULL, "sanity");
357   set_secondary_supers(Universe::the_empty_klass_array());
358   return NULL;
359 }
360 
361 
362 // superklass links
363 InstanceKlass* Klass::superklass() const {
364   assert(super() == NULL || super()->is_instance_klass(), "must be instance klass");
365   return _super == NULL ? NULL : InstanceKlass::cast(_super);
366 }
367 
368 // subklass links.  Used by the compiler (and vtable initialization)
369 // May be cleaned concurrently, so must use the Compile_lock.
370 // The log parameter is for clean_weak_klass_links to report unlinked classes.
371 Klass* Klass::subklass(bool log) const {
372   // Need load_acquire on the _subklass, because it races with inserts that
373   // publishes freshly initialized data.
374   for (Klass* chain = Atomic::load_acquire(&_subklass);
375        chain != NULL;
376        // Do not need load_acquire on _next_sibling, because inserts never
377        // create _next_sibling edges to dead data.
378        chain = Atomic::load(&chain->_next_sibling))
379   {
380     if (chain->is_loader_alive()) {
381       return chain;
382     } else if (log) {
383       if (log_is_enabled(Trace, class, unload)) {
384         ResourceMark rm;
385         log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
386       }
387     }
388   }
389   return NULL;
390 }
391 
392 Klass* Klass::next_sibling(bool log) const {
393   // Do not need load_acquire on _next_sibling, because inserts never
394   // create _next_sibling edges to dead data.
395   for (Klass* chain = Atomic::load(&_next_sibling);
396        chain != NULL;
397        chain = Atomic::load(&chain->_next_sibling)) {
398     // Only return alive klass, there may be stale klass
399     // in this chain if cleaned concurrently.
400     if (chain->is_loader_alive()) {
401       return chain;
402     } else if (log) {
403       if (log_is_enabled(Trace, class, unload)) {
404         ResourceMark rm;
405         log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
406       }
407     }
408   }
409   return NULL;
410 }
411 
412 void Klass::set_subklass(Klass* s) {
413   assert(s != this, "sanity check");
414   Atomic::release_store(&_subklass, s);
415 }
416 
417 void Klass::set_next_sibling(Klass* s) {
418   assert(s != this, "sanity check");
419   // Does not need release semantics. If used by cleanup, it will link to
420   // already safely published data, and if used by inserts, will be published
421   // safely using cmpxchg.
422   Atomic::store(&_next_sibling, s);
423 }
424 
425 void Klass::append_to_sibling_list() {
426   if (Universe::is_fully_initialized()) {
427     assert_locked_or_safepoint(Compile_lock);
428   }
429   debug_only(verify();)
430   // add ourselves to superklass' subklass list
431   InstanceKlass* super = superklass();
432   if (super == NULL) return;        // special case: class Object
433   assert((!super->is_interface()    // interfaces cannot be supers
434           && (super->superklass() == NULL || !is_interface())),
435          "an interface can only be a subklass of Object");
436 
437   // Make sure there is no stale subklass head
438   super->clean_subklass();
439 
440   for (;;) {
441     Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
442     if (prev_first_subklass != NULL) {
443       // set our sibling to be the superklass' previous first subklass
444       assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
445       set_next_sibling(prev_first_subklass);
446     }
447     // Note that the prev_first_subklass is always alive, meaning no sibling_next links
448     // are ever created to not alive klasses. This is an important invariant of the lock-free
449     // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
450     if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
451       return;
452     }
453   }
454   debug_only(verify();)
455 }
456 
457 void Klass::clean_subklass() {
458   for (;;) {
459     // Need load_acquire, due to contending with concurrent inserts
460     Klass* subklass = Atomic::load_acquire(&_subklass);
461     if (subklass == NULL || subklass->is_loader_alive()) {
462       return;
463     }
464     // Try to fix _subklass until it points at something not dead.
465     Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
466   }
467 }
468 
469 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
470   if (!ClassUnloading || !unloading_occurred) {
471     return;
472   }
473 
474   Klass* root = vmClasses::Object_klass();
475   Stack<Klass*, mtGC> stack;
476 
477   stack.push(root);
478   while (!stack.is_empty()) {
479     Klass* current = stack.pop();
480 
481     assert(current->is_loader_alive(), "just checking, this should be live");
482 
483     // Find and set the first alive subklass
484     Klass* sub = current->subklass(true);
485     current->clean_subklass();
486     if (sub != NULL) {
487       stack.push(sub);
488     }
489 
490     // Find and set the first alive sibling
491     Klass* sibling = current->next_sibling(true);
492     current->set_next_sibling(sibling);
493     if (sibling != NULL) {
494       stack.push(sibling);
495     }
496 
497     // Clean the implementors list and method data.
498     if (clean_alive_klasses && current->is_instance_klass()) {
499       InstanceKlass* ik = InstanceKlass::cast(current);
500       ik->clean_weak_instanceklass_links();
501 
502       // JVMTI RedefineClasses creates previous versions that are not in
503       // the class hierarchy, so process them here.
504       while ((ik = ik->previous_versions()) != NULL) {
505         ik->clean_weak_instanceklass_links();
506       }
507     }
508   }
509 }
510 
511 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
512   if (log_is_enabled(Trace, cds)) {
513     ResourceMark rm;
514     log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
515   }
516 
517   it->push(&_name);
518   it->push(&_secondary_super_cache);
519   it->push(&_secondary_supers);
520   for (int i = 0; i < _primary_super_limit; i++) {
521     it->push(&_primary_supers[i]);
522   }
523   it->push(&_super);
524   if (!Arguments::is_dumping_archive()) {
525     // If dumping archive, these may point to excluded classes. There's no need
526     // to follow these pointers anyway, as they will be set to NULL in
527     // remove_unshareable_info().
528     it->push((Klass**)&_subklass);
529     it->push((Klass**)&_next_sibling);
530     it->push(&_next_link);
531   }
532 
533   vtableEntry* vt = start_of_vtable();
534   for (int i=0; i<vtable_length(); i++) {
535     it->push(vt[i].method_addr());
536   }
537 }
538 
539 #if INCLUDE_CDS
540 void Klass::remove_unshareable_info() {
541   assert (Arguments::is_dumping_archive(),
542           "only called during CDS dump time");
543   JFR_ONLY(REMOVE_ID(this);)
544   if (log_is_enabled(Trace, cds, unshareable)) {
545     ResourceMark rm;
546     log_trace(cds, unshareable)("remove: %s", external_name());
547   }
548 
549   set_subklass(NULL);
550   set_next_sibling(NULL);
551   set_next_link(NULL);
552 
553   // Null out class_loader_data because we don't share that yet.
554   set_class_loader_data(NULL);
555   set_is_shared();
556 }
557 
558 void Klass::remove_java_mirror() {
559   Arguments::assert_is_dumping_archive();
560   if (log_is_enabled(Trace, cds, unshareable)) {
561     ResourceMark rm;
562     log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
563   }
564   // Just null out the mirror.  The class_loader_data() no longer exists.
565   clear_java_mirror_handle();
566 }
567 
568 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
569   assert(is_klass(), "ensure C++ vtable is restored");
570   assert(is_shared(), "must be set");
571   JFR_ONLY(RESTORE_ID(this);)
572   if (log_is_enabled(Trace, cds, unshareable)) {
573     ResourceMark rm(THREAD);
574     log_trace(cds, unshareable)("restore: %s", external_name());
575   }
576 
577   // If an exception happened during CDS restore, some of these fields may already be
578   // set.  We leave the class on the CLD list, even if incomplete so that we don't
579   // modify the CLD list outside a safepoint.
580   if (class_loader_data() == NULL) {
581     set_class_loader_data(loader_data);
582 
583     // Add to class loader list first before creating the mirror
584     // (same order as class file parsing)
585     loader_data->add_class(this);
586   }
587 
588   Handle loader(THREAD, loader_data->class_loader());
589   ModuleEntry* module_entry = NULL;
590   Klass* k = this;
591   if (k->is_objArray_klass()) {
592     k = ObjArrayKlass::cast(k)->bottom_klass();
593   }
594   // Obtain klass' module.
595   if (k->is_instance_klass()) {
596     InstanceKlass* ik = (InstanceKlass*) k;
597     module_entry = ik->module();
598   } else {
599     module_entry = ModuleEntryTable::javabase_moduleEntry();
600   }
601   // Obtain java.lang.Module, if available
602   Handle module_handle(THREAD, ((module_entry != NULL) ? module_entry->module() : (oop)NULL));
603 
604   if (this->has_archived_mirror_index()) {
605     ResourceMark rm(THREAD);
606     log_debug(cds, mirror)("%s has raw archived mirror", external_name());
607     if (ArchiveHeapLoader::are_archived_mirrors_available()) {
608       bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
609                                                               protection_domain,
610                                                               CHECK);
611       if (present) {
612         return;
613       }
614     }
615 
616     // No archived mirror data
617     log_debug(cds, mirror)("No archived mirror data for %s", external_name());
618     clear_java_mirror_handle();
619     this->clear_archived_mirror_index();
620   }
621 
622   // Only recreate it if not present.  A previous attempt to restore may have
623   // gotten an OOM later but keep the mirror if it was created.
624   if (java_mirror() == NULL) {
625     ResourceMark rm(THREAD);
626     log_trace(cds, mirror)("Recreate mirror for %s", external_name());
627     java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
628   }
629 }
630 #endif // INCLUDE_CDS
631 
632 #if INCLUDE_CDS_JAVA_HEAP
633 oop Klass::archived_java_mirror() {
634   assert(has_archived_mirror_index(), "must have archived mirror");
635   return HeapShared::get_root(_archived_mirror_index);
636 }
637 
638 void Klass::clear_archived_mirror_index() {
639   if (_archived_mirror_index >= 0) {
640     HeapShared::clear_root(_archived_mirror_index);
641   }
642   _archived_mirror_index = -1;
643 }
644 
645 // No GC barrier
646 void Klass::set_archived_java_mirror(oop m) {
647   assert(DumpSharedSpaces, "called only during runtime");
648   _archived_mirror_index = HeapShared::append_root(m);
649 }
650 #endif // INCLUDE_CDS_JAVA_HEAP
651 
652 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
653   if (length > max_length) {
654     if (!THREAD->in_retryable_allocation()) {
655       report_java_out_of_memory("Requested array size exceeds VM limit");
656       JvmtiExport::post_array_size_exhausted();
657       THROW_OOP(Universe::out_of_memory_error_array_size());
658     } else {
659       THROW_OOP(Universe::out_of_memory_error_retry());
660     }
661   } else if (length < 0) {
662     THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
663   }
664 }
665 
666 // Replace the last '+' char with '/'.
667 static char* convert_hidden_name_to_java(Symbol* name) {
668   size_t name_len = name->utf8_length();
669   char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
670   name->as_klass_external_name(result, (int)name_len + 1);
671   for (int index = (int)name_len; index > 0; index--) {
672     if (result[index] == '+') {
673       result[index] = JVM_SIGNATURE_SLASH;
674       break;
675     }
676   }
677   return result;
678 }
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_hidden()) {
686       char* result = convert_hidden_name_to_java(name());
687       return result;
688     }
689   } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
690     char* result = convert_hidden_name_to_java(name());
691     return result;
692   }
693   if (name() == NULL)  return "<unknown>";
694   return name()->as_klass_external_name();
695 }
696 
697 const char* Klass::signature_name() const {
698   if (name() == NULL)  return "<unknown>";
699   if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
700     size_t name_len = name()->utf8_length();
701     char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
702     name()->as_C_string(result, (int)name_len + 1);
703     for (int index = (int)name_len; index > 0; index--) {
704       if (result[index] == '+') {
705         result[index] = JVM_SIGNATURE_DOT;
706         break;
707       }
708     }
709     return result;
710   }
711   return name()->as_C_string();
712 }
713 
714 const char* Klass::external_kind() const {
715   if (is_interface()) return "interface";
716   if (is_abstract()) return "abstract class";
717   return "class";
718 }
719 
720 // Unless overridden, jvmti_class_status has no flags set.
721 jint Klass::jvmti_class_status() const {
722   return 0;
723 }
724 
725 
726 // Printing
727 
728 void Klass::print_on(outputStream* st) const {
729   ResourceMark rm;
730   // print title
731   st->print("%s", internal_name());
732   print_address_on(st);
733   st->cr();
734 }
735 
736 #define BULLET  " - "
737 
738 // Caller needs ResourceMark
739 void Klass::oop_print_on(oop obj, outputStream* st) {
740   // print title
741   st->print_cr("%s ", internal_name());
742   obj->print_address_on(st);
743 
744   if (WizardMode) {
745      // print header
746      obj->mark().print_on(st);
747      st->cr();
748      st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
749      st->cr();
750   }
751 
752   // print class
753   st->print(BULLET"klass: ");
754   obj->klass()->print_value_on(st);
755   st->cr();
756 }
757 
758 void Klass::oop_print_value_on(oop obj, outputStream* st) {
759   // print title
760   ResourceMark rm;              // Cannot print in debug mode without this
761   st->print("%s", internal_name());
762   obj->print_address_on(st);
763 }
764 
765 // Verification
766 
767 void Klass::verify_on(outputStream* st) {
768 
769   // This can be expensive, but it is worth checking that this klass is actually
770   // in the CLD graph but not in production.
771   assert(Metaspace::contains((address)this), "Should be");
772 
773   guarantee(this->is_klass(),"should be klass");
774 
775   if (super() != NULL) {
776     guarantee(super()->is_klass(), "should be klass");
777   }
778   if (secondary_super_cache() != NULL) {
779     Klass* ko = secondary_super_cache();
780     guarantee(ko->is_klass(), "should be klass");
781   }
782   for ( uint i = 0; i < primary_super_limit(); i++ ) {
783     Klass* ko = _primary_supers[i];
784     if (ko != NULL) {
785       guarantee(ko->is_klass(), "should be klass");
786     }
787   }
788 
789   if (java_mirror_no_keepalive() != NULL) {
790     guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
791   }
792 }
793 
794 void Klass::oop_verify_on(oop obj, outputStream* st) {
795   guarantee(oopDesc::is_oop(obj),  "should be oop");
796   guarantee(obj->klass()->is_klass(), "klass field is not a klass");
797 }
798 
799 bool Klass::is_valid(Klass* k) {
800   if (!is_aligned(k, sizeof(MetaWord))) return false;
801   if ((size_t)k < os::min_page_size()) return false;
802 
803   if (!os::is_readable_range(k, k + 1)) return false;
804   if (!Metaspace::contains(k)) return false;
805 
806   if (!Symbol::is_valid(k->name())) return false;
807   return ClassLoaderDataGraph::is_valid(k->class_loader_data());
808 }
809 
810 Method* Klass::method_at_vtable(int index)  {
811 #ifndef PRODUCT
812   assert(index >= 0, "valid vtable index");
813   if (DebugVtables) {
814     verify_vtable_index(index);
815   }
816 #endif
817   return start_of_vtable()[index].method();
818 }
819 
820 
821 #ifndef PRODUCT
822 
823 bool Klass::verify_vtable_index(int i) {
824   int limit = vtable_length()/vtableEntry::size();
825   assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
826   return true;
827 }
828 
829 #endif // PRODUCT
830 
831 // Caller needs ResourceMark
832 // joint_in_module_of_loader provides an optimization if 2 classes are in
833 // the same module to succinctly print out relevant information about their
834 // module name and class loader's name_and_id for error messages.
835 // Format:
836 //   <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
837 //                      are in module <module-name>[@<version>]
838 //                      of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
839 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
840   assert(module() == class2->module(), "classes do not have the same module");
841   const char* class1_name = external_name();
842   size_t len = strlen(class1_name) + 1;
843 
844   const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
845   len += strlen(class2_description);
846 
847   len += strlen(" and ");
848 
849   char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
850 
851   // Just return the FQN if error when allocating string
852   if (joint_description == NULL) {
853     return class1_name;
854   }
855 
856   jio_snprintf(joint_description, len, "%s and %s",
857                class1_name,
858                class2_description);
859 
860   return joint_description;
861 }
862 
863 // Caller needs ResourceMark
864 // class_in_module_of_loader provides a standard way to include
865 // relevant information about a class, such as its module name as
866 // well as its class loader's name_and_id, in error messages and logging.
867 // Format:
868 //   <fully-qualified-external-class-name> is in module <module-name>[@<version>]
869 //                                         of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
870 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
871   // 1. fully qualified external name of class
872   const char* klass_name = external_name();
873   size_t len = strlen(klass_name) + 1;
874 
875   // 2. module name + @version
876   const char* module_name = "";
877   const char* version = "";
878   bool has_version = false;
879   bool module_is_named = false;
880   const char* module_name_phrase = "";
881   const Klass* bottom_klass = is_objArray_klass() ?
882                                 ObjArrayKlass::cast(this)->bottom_klass() : this;
883   if (bottom_klass->is_instance_klass()) {
884     ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
885     if (module->is_named()) {
886       module_is_named = true;
887       module_name_phrase = "module ";
888       module_name = module->name()->as_C_string();
889       len += strlen(module_name);
890       // Use version if exists and is not a jdk module
891       if (module->should_show_version()) {
892         has_version = true;
893         version = module->version()->as_C_string();
894         // Include stlen(version) + 1 for the "@"
895         len += strlen(version) + 1;
896       }
897     } else {
898       module_name = UNNAMED_MODULE;
899       len += UNNAMED_MODULE_LEN;
900     }
901   } else {
902     // klass is an array of primitives, module is java.base
903     module_is_named = true;
904     module_name_phrase = "module ";
905     module_name = JAVA_BASE_NAME;
906     len += JAVA_BASE_NAME_LEN;
907   }
908 
909   // 3. class loader's name_and_id
910   ClassLoaderData* cld = class_loader_data();
911   assert(cld != NULL, "class_loader_data should not be null");
912   const char* loader_name_and_id = cld->loader_name_and_id();
913   len += strlen(loader_name_and_id);
914 
915   // 4. include parent loader information
916   const char* parent_loader_phrase = "";
917   const char* parent_loader_name_and_id = "";
918   if (include_parent_loader &&
919       !cld->is_builtin_class_loader_data()) {
920     oop parent_loader = java_lang_ClassLoader::parent(class_loader());
921     ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
922     // The parent loader's ClassLoaderData could be null if it is
923     // a delegating class loader that has never defined a class.
924     // In this case the loader's name must be obtained via the parent loader's oop.
925     if (parent_cld == NULL) {
926       oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
927       if (cl_name_and_id != NULL) {
928         parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
929       }
930     } else {
931       parent_loader_name_and_id = parent_cld->loader_name_and_id();
932     }
933     parent_loader_phrase = ", parent loader ";
934     len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
935   }
936 
937   // Start to construct final full class description string
938   len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
939   len += strlen(module_name_phrase) + strlen(" of loader ");
940 
941   char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
942 
943   // Just return the FQN if error when allocating string
944   if (class_description == NULL) {
945     return klass_name;
946   }
947 
948   jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
949                klass_name,
950                (use_are) ? "are" : "is",
951                module_name_phrase,
952                module_name,
953                (has_version) ? "@" : "",
954                (has_version) ? version : "",
955                loader_name_and_id,
956                parent_loader_phrase,
957                parent_loader_name_and_id);
958 
959   return class_description;
960 }