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