1 /*
  2  * Copyright (c) 1997, 2021, 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/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 "logging/log.hpp"
 38 #include "memory/metadataFactory.hpp"
 39 #include "memory/metaspaceClosure.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 "prims/jvmtiExport.hpp"
 49 #include "runtime/arguments.hpp"
 50 #include "runtime/atomic.hpp"
 51 #include "runtime/handles.inline.hpp"
 52 #include "utilities/macros.hpp"
 53 #include "utilities/powerOfTwo.hpp"
 54 #include "utilities/stack.inline.hpp"
 55 
 56 void Klass::set_java_mirror(Handle m) {
 57   assert(!m.is_null(), "New mirror should never be null.");
 58   assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
 59   _java_mirror = class_loader_data()->add_handle(m);
 60 }
 61 
 62 oop Klass::java_mirror_no_keepalive() const {
 63   return _java_mirror.peek();
 64 }
 65 
 66 bool Klass::is_cloneable() const {
 67   return _access_flags.is_cloneable_fast() ||
 68          is_subtype_of(vmClasses::Cloneable_klass());
 69 }
 70 
 71 void Klass::set_is_cloneable() {
 72   if (name() == vmSymbols::java_lang_invoke_MemberName()) {
 73     assert(is_final(), "no subclasses allowed");
 74     // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
 75   } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
 76     // Reference cloning should not be intrinsified and always happen in JVM_Clone.
 77   } else {
 78     _access_flags.set_is_cloneable_fast();
 79   }
 80 }
 81 
 82 void Klass::set_name(Symbol* n) {
 83   _name = n;
 84   if (_name != NULL) _name->increment_refcount();
 85 
 86   if (Arguments::is_dumping_archive() && is_instance_klass()) {
 87     SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
 88   }
 89 }
 90 
 91 bool Klass::is_subclass_of(const Klass* k) const {
 92   // Run up the super chain and check
 93   if (this == k) return true;
 94 
 95   Klass* t = const_cast<Klass*>(this)->super();
 96 
 97   while (t != NULL) {
 98     if (t == k) return true;
 99     t = t->super();
100   }
101   return false;
102 }
103 
104 void Klass::release_C_heap_structures(bool release_constant_pool) {
105   if (_name != NULL) _name->decrement_refcount();
106 }
107 
108 bool Klass::search_secondary_supers(Klass* k) const {
109   // Put some extra logic here out-of-line, before the search proper.
110   // This cuts down the size of the inline method.
111 
112   // This is necessary, since I am never in my own secondary_super list.
113   if (this == k)
114     return true;
115   // Scan the array-of-objects for a match
116   int cnt = secondary_supers()->length();
117   for (int i = 0; i < cnt; i++) {
118     if (secondary_supers()->at(i) == k) {
119       ((Klass*)this)->set_secondary_super_cache(k);
120       return true;
121     }
122   }
123   return false;
124 }
125 
126 // Return self, except for abstract classes with exactly 1
127 // implementor.  Then return the 1 concrete implementation.
128 Klass *Klass::up_cast_abstract() {
129   Klass *r = this;
130   while( r->is_abstract() ) {   // Receiver is abstract?
131     Klass *s = r->subklass();   // Check for exactly 1 subklass
132     if (s == NULL || s->next_sibling() != NULL) // Oops; wrong count; give up
133       return this;              // Return 'this' as a no-progress flag
134     r = s;                    // Loop till find concrete class
135   }
136   return r;                   // Return the 1 concrete class
137 }
138 
139 // Find LCA in class hierarchy
140 Klass *Klass::LCA( Klass *k2 ) {
141   Klass *k1 = this;
142   while( 1 ) {
143     if( k1->is_subtype_of(k2) ) return k2;
144     if( k2->is_subtype_of(k1) ) return k1;
145     k1 = k1->super();
146     k2 = k2->super();
147   }
148 }
149 
150 
151 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
152   ResourceMark rm(THREAD);
153   THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
154             : vmSymbols::java_lang_InstantiationException(), external_name());
155 }
156 
157 
158 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
159   ResourceMark rm(THREAD);
160   assert(s != NULL, "Throw NPE!");
161   THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
162             err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
163 }
164 
165 
166 void Klass::initialize(TRAPS) {
167   ShouldNotReachHere();
168 }
169 
170 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
171 #ifdef ASSERT
172   tty->print_cr("Error: find_field called on a klass oop."
173                 " Likely error: reflection method does not correctly"
174                 " wrap return value in a mirror object.");
175 #endif
176   ShouldNotReachHere();
177   return NULL;
178 }
179 
180 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
181                                       OverpassLookupMode overpass_mode,
182                                       PrivateLookupMode private_mode) const {
183 #ifdef ASSERT
184   tty->print_cr("Error: uncached_lookup_method called on a klass oop."
185                 " Likely error: reflection method does not correctly"
186                 " wrap return value in a mirror object.");
187 #endif
188   ShouldNotReachHere();
189   return NULL;
190 }
191 
192 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
193   return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
194 }
195 
196 static markWord make_prototype(Klass* kls) {
197   markWord prototype = markWord::prototype();
198 #ifdef _LP64
199   if (UseCompactObjectHeaders) {
200     prototype = prototype.set_klass(kls);
201   }
202 #endif
203   return prototype;
204 }
205 
206 // "Normal" instantiation is preceeded by a MetaspaceObj allocation
207 // which zeros out memory - calloc equivalent.
208 // The constructor is also used from CppVtableCloner,
209 // which doesn't zero out the memory before calling the constructor.
210 Klass::Klass(KlassID id) : _id(id),
211                            _prototype_header(make_prototype(this)),
212                            _shared_class_path_index(-1) {
213   CDS_ONLY(_shared_class_flags = 0;)
214   CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
215   _primary_supers[0] = this;
216   set_super_check_offset(in_bytes(primary_supers_offset()));
217 }
218 
219 jint Klass::array_layout_helper(BasicType etype) {
220   assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
221   // Note that T_ARRAY is not allowed here.
222   int  hsize = arrayOopDesc::base_offset_in_bytes(etype);
223   int  esize = type2aelembytes(etype);
224   bool isobj = (etype == T_OBJECT);
225   int  tag   =  isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
226   int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
227 
228   assert(lh < (int)_lh_neutral_value, "must look like an array layout");
229   assert(layout_helper_is_array(lh), "correct kind");
230   assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
231   assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
232   assert(layout_helper_header_size(lh) == hsize, "correct decode");
233   assert(layout_helper_element_type(lh) == etype, "correct decode");
234   assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
235 
236   return lh;
237 }
238 
239 bool Klass::can_be_primary_super_slow() const {
240   if (super() == NULL)
241     return true;
242   else if (super()->super_depth() >= primary_super_limit()-1)
243     return false;
244   else
245     return true;
246 }
247 
248 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
249   if (k == NULL) {
250     set_super(NULL);
251     _primary_supers[0] = this;
252     assert(super_depth() == 0, "Object must already be initialized properly");
253   } else if (k != super() || k == vmClasses::Object_klass()) {
254     assert(super() == NULL || super() == vmClasses::Object_klass(),
255            "initialize this only once to a non-trivial value");
256     set_super(k);
257     Klass* sup = k;
258     int sup_depth = sup->super_depth();
259     juint my_depth  = MIN2(sup_depth + 1, (int)primary_super_limit());
260     if (!can_be_primary_super_slow())
261       my_depth = primary_super_limit();
262     for (juint i = 0; i < my_depth; i++) {
263       _primary_supers[i] = sup->_primary_supers[i];
264     }
265     Klass* *super_check_cell;
266     if (my_depth < primary_super_limit()) {
267       _primary_supers[my_depth] = this;
268       super_check_cell = &_primary_supers[my_depth];
269     } else {
270       // Overflow of the primary_supers array forces me to be secondary.
271       super_check_cell = &_secondary_super_cache;
272     }
273     set_super_check_offset((address)super_check_cell - (address) this);
274 
275 #ifdef ASSERT
276     {
277       juint j = super_depth();
278       assert(j == my_depth, "computed accessor gets right answer");
279       Klass* t = this;
280       while (!t->can_be_primary_super()) {
281         t = t->super();
282         j = t->super_depth();
283       }
284       for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
285         assert(primary_super_of_depth(j1) == NULL, "super list padding");
286       }
287       while (t != NULL) {
288         assert(primary_super_of_depth(j) == t, "super list initialization");
289         t = t->super();
290         --j;
291       }
292       assert(j == (juint)-1, "correct depth count");
293     }
294 #endif
295   }
296 
297   if (secondary_supers() == NULL) {
298 
299     // Now compute the list of secondary supertypes.
300     // Secondaries can occasionally be on the super chain,
301     // if the inline "_primary_supers" array overflows.
302     int extras = 0;
303     Klass* p;
304     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
305       ++extras;
306     }
307 
308     ResourceMark rm(THREAD);  // need to reclaim GrowableArrays allocated below
309 
310     // Compute the "real" non-extra secondaries.
311     GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
312     if (secondaries == NULL) {
313       // secondary_supers set by compute_secondary_supers
314       return;
315     }
316 
317     GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
318 
319     for (p = super(); !(p == NULL || p->can_be_primary_super()); p = p->super()) {
320       int i;                    // Scan for overflow primaries being duplicates of 2nd'arys
321 
322       // This happens frequently for very deeply nested arrays: the
323       // primary superclass chain overflows into the secondary.  The
324       // secondary list contains the element_klass's secondaries with
325       // an extra array dimension added.  If the element_klass's
326       // secondary list already contains some primary overflows, they
327       // (with the extra level of array-ness) will collide with the
328       // normal primary superclass overflows.
329       for( i = 0; i < secondaries->length(); i++ ) {
330         if( secondaries->at(i) == p )
331           break;
332       }
333       if( i < secondaries->length() )
334         continue;               // It's a dup, don't put it in
335       primaries->push(p);
336     }
337     // Combine the two arrays into a metadata object to pack the array.
338     // The primaries are added in the reverse order, then the secondaries.
339     int new_length = primaries->length() + secondaries->length();
340     Array<Klass*>* s2 = MetadataFactory::new_array<Klass*>(
341                                        class_loader_data(), new_length, CHECK);
342     int fill_p = primaries->length();
343     for (int j = 0; j < fill_p; j++) {
344       s2->at_put(j, primaries->pop());  // add primaries in reverse order.
345     }
346     for( int j = 0; j < secondaries->length(); j++ ) {
347       s2->at_put(j+fill_p, secondaries->at(j));  // add secondaries on the end.
348     }
349 
350   #ifdef ASSERT
351       // We must not copy any NULL placeholders left over from bootstrap.
352     for (int j = 0; j < s2->length(); j++) {
353       assert(s2->at(j) != NULL, "correct bootstrapping order");
354     }
355   #endif
356 
357     set_secondary_supers(s2);
358   }
359 }
360 
361 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
362                                                        Array<InstanceKlass*>* transitive_interfaces) {
363   assert(num_extra_slots == 0, "override for complex klasses");
364   assert(transitive_interfaces == NULL, "sanity");
365   set_secondary_supers(Universe::the_empty_klass_array());
366   return NULL;
367 }
368 
369 
370 // superklass links
371 InstanceKlass* Klass::superklass() const {
372   assert(super() == NULL || super()->is_instance_klass(), "must be instance klass");
373   return _super == NULL ? NULL : InstanceKlass::cast(_super);
374 }
375 
376 // subklass links.  Used by the compiler (and vtable initialization)
377 // May be cleaned concurrently, so must use the Compile_lock.
378 // The log parameter is for clean_weak_klass_links to report unlinked classes.
379 Klass* Klass::subklass(bool log) const {
380   // Need load_acquire on the _subklass, because it races with inserts that
381   // publishes freshly initialized data.
382   for (Klass* chain = Atomic::load_acquire(&_subklass);
383        chain != NULL;
384        // Do not need load_acquire on _next_sibling, because inserts never
385        // create _next_sibling edges to dead data.
386        chain = Atomic::load(&chain->_next_sibling))
387   {
388     if (chain->is_loader_alive()) {
389       return chain;
390     } else if (log) {
391       if (log_is_enabled(Trace, class, unload)) {
392         ResourceMark rm;
393         log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
394       }
395     }
396   }
397   return NULL;
398 }
399 
400 Klass* Klass::next_sibling(bool log) const {
401   // Do not need load_acquire on _next_sibling, because inserts never
402   // create _next_sibling edges to dead data.
403   for (Klass* chain = Atomic::load(&_next_sibling);
404        chain != NULL;
405        chain = Atomic::load(&chain->_next_sibling)) {
406     // Only return alive klass, there may be stale klass
407     // in this chain if cleaned concurrently.
408     if (chain->is_loader_alive()) {
409       return chain;
410     } else if (log) {
411       if (log_is_enabled(Trace, class, unload)) {
412         ResourceMark rm;
413         log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
414       }
415     }
416   }
417   return NULL;
418 }
419 
420 void Klass::set_subklass(Klass* s) {
421   assert(s != this, "sanity check");
422   Atomic::release_store(&_subklass, s);
423 }
424 
425 void Klass::set_next_sibling(Klass* s) {
426   assert(s != this, "sanity check");
427   // Does not need release semantics. If used by cleanup, it will link to
428   // already safely published data, and if used by inserts, will be published
429   // safely using cmpxchg.
430   Atomic::store(&_next_sibling, s);
431 }
432 
433 void Klass::append_to_sibling_list() {
434   if (Universe::is_fully_initialized()) {
435     assert_locked_or_safepoint(Compile_lock);
436   }
437   debug_only(verify();)
438   // add ourselves to superklass' subklass list
439   InstanceKlass* super = superklass();
440   if (super == NULL) return;        // special case: class Object
441   assert((!super->is_interface()    // interfaces cannot be supers
442           && (super->superklass() == NULL || !is_interface())),
443          "an interface can only be a subklass of Object");
444 
445   // Make sure there is no stale subklass head
446   super->clean_subklass();
447 
448   for (;;) {
449     Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
450     if (prev_first_subklass != NULL) {
451       // set our sibling to be the superklass' previous first subklass
452       assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
453       set_next_sibling(prev_first_subklass);
454     }
455     // Note that the prev_first_subklass is always alive, meaning no sibling_next links
456     // are ever created to not alive klasses. This is an important invariant of the lock-free
457     // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
458     if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
459       return;
460     }
461   }
462   debug_only(verify();)
463 }
464 
465 void Klass::clean_subklass() {
466   for (;;) {
467     // Need load_acquire, due to contending with concurrent inserts
468     Klass* subklass = Atomic::load_acquire(&_subklass);
469     if (subklass == NULL || subklass->is_loader_alive()) {
470       return;
471     }
472     // Try to fix _subklass until it points at something not dead.
473     Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
474   }
475 }
476 
477 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
478   if (!ClassUnloading || !unloading_occurred) {
479     return;
480   }
481 
482   Klass* root = vmClasses::Object_klass();
483   Stack<Klass*, mtGC> stack;
484 
485   stack.push(root);
486   while (!stack.is_empty()) {
487     Klass* current = stack.pop();
488 
489     assert(current->is_loader_alive(), "just checking, this should be live");
490 
491     // Find and set the first alive subklass
492     Klass* sub = current->subklass(true);
493     current->clean_subklass();
494     if (sub != NULL) {
495       stack.push(sub);
496     }
497 
498     // Find and set the first alive sibling
499     Klass* sibling = current->next_sibling(true);
500     current->set_next_sibling(sibling);
501     if (sibling != NULL) {
502       stack.push(sibling);
503     }
504 
505     // Clean the implementors list and method data.
506     if (clean_alive_klasses && current->is_instance_klass()) {
507       InstanceKlass* ik = InstanceKlass::cast(current);
508       ik->clean_weak_instanceklass_links();
509 
510       // JVMTI RedefineClasses creates previous versions that are not in
511       // the class hierarchy, so process them here.
512       while ((ik = ik->previous_versions()) != NULL) {
513         ik->clean_weak_instanceklass_links();
514       }
515     }
516   }
517 }
518 
519 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
520   if (log_is_enabled(Trace, cds)) {
521     ResourceMark rm;
522     log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
523   }
524 
525   it->push(&_name);
526   it->push(&_secondary_super_cache);
527   it->push(&_secondary_supers);
528   for (int i = 0; i < _primary_super_limit; i++) {
529     it->push(&_primary_supers[i]);
530   }
531   it->push(&_super);
532   it->push((Klass**)&_subklass);
533   it->push((Klass**)&_next_sibling);
534   it->push(&_next_link);
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 void Klass::remove_unshareable_info() {
543   assert (Arguments::is_dumping_archive(),
544           "only called during CDS dump time");
545   JFR_ONLY(REMOVE_ID(this);)
546   if (log_is_enabled(Trace, cds, unshareable)) {
547     ResourceMark rm;
548     log_trace(cds, unshareable)("remove: %s", external_name());
549   }
550 
551   set_subklass(NULL);
552   set_next_sibling(NULL);
553   set_next_link(NULL);
554 
555   // Null out class_loader_data because we don't share that yet.
556   set_class_loader_data(NULL);
557   set_is_shared();
558 }
559 
560 void Klass::remove_java_mirror() {
561   Arguments::assert_is_dumping_archive();
562   if (log_is_enabled(Trace, cds, unshareable)) {
563     ResourceMark rm;
564     log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
565   }
566   // Just null out the mirror.  The class_loader_data() no longer exists.
567   clear_java_mirror_handle();
568 }
569 
570 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
571   assert(is_klass(), "ensure C++ vtable is restored");
572   assert(is_shared(), "must be set");
573   JFR_ONLY(RESTORE_ID(this);)
574   if (log_is_enabled(Trace, cds, unshareable)) {
575     ResourceMark rm(THREAD);
576     log_trace(cds, unshareable)("restore: %s", external_name());
577   }
578 
579   // If an exception happened during CDS restore, some of these fields may already be
580   // set.  We leave the class on the CLD list, even if incomplete so that we don't
581   // modify the CLD list outside a safepoint.
582   if (class_loader_data() == NULL) {
583     set_class_loader_data(loader_data);
584 
585     // Add to class loader list first before creating the mirror
586     // (same order as class file parsing)
587     loader_data->add_class(this);
588   }
589 
590   Handle loader(THREAD, loader_data->class_loader());
591   ModuleEntry* module_entry = NULL;
592   Klass* k = this;
593   if (k->is_objArray_klass()) {
594     k = ObjArrayKlass::cast(k)->bottom_klass();
595   }
596   // Obtain klass' module.
597   if (k->is_instance_klass()) {
598     InstanceKlass* ik = (InstanceKlass*) k;
599     module_entry = ik->module();
600   } else {
601     module_entry = ModuleEntryTable::javabase_moduleEntry();
602   }
603   // Obtain java.lang.Module, if available
604   Handle module_handle(THREAD, ((module_entry != NULL) ? module_entry->module() : (oop)NULL));
605 
606   if (this->has_archived_mirror_index()) {
607     ResourceMark rm(THREAD);
608     log_debug(cds, mirror)("%s has raw archived mirror", external_name());
609     if (HeapShared::open_archive_heap_region_mapped()) {
610       bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
611                                                               protection_domain,
612                                                               CHECK);
613       if (present) {
614         return;
615       }
616     }
617 
618     // No archived mirror data
619     log_debug(cds, mirror)("No archived mirror data for %s", external_name());
620     clear_java_mirror_handle();
621     this->clear_archived_mirror_index();
622   }
623 
624   // Only recreate it if not present.  A previous attempt to restore may have
625   // gotten an OOM later but keep the mirror if it was created.
626   if (java_mirror() == NULL) {
627     ResourceMark rm(THREAD);
628     log_trace(cds, mirror)("Recreate mirror for %s", external_name());
629     java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
630   }
631 }
632 
633 #if INCLUDE_CDS_JAVA_HEAP
634 oop Klass::archived_java_mirror() {
635   assert(has_archived_mirror_index(), "must have archived mirror");
636   return HeapShared::get_root(_archived_mirror_index);
637 }
638 
639 void Klass::clear_archived_mirror_index() {
640   if (_archived_mirror_index >= 0) {
641     HeapShared::clear_root(_archived_mirror_index);
642   }
643   _archived_mirror_index = -1;
644 }
645 
646 // No GC barrier
647 void Klass::set_archived_java_mirror(oop m) {
648   assert(DumpSharedSpaces, "called only during runtime");
649   _archived_mirror_index = HeapShared::append_root(m);
650 }
651 #endif // INCLUDE_CDS_JAVA_HEAP
652 
653 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
654   if (length > max_length) {
655     if (!THREAD->in_retryable_allocation()) {
656       report_java_out_of_memory("Requested array size exceeds VM limit");
657       JvmtiExport::post_array_size_exhausted();
658       THROW_OOP(Universe::out_of_memory_error_array_size());
659     } else {
660       THROW_OOP(Universe::out_of_memory_error_retry());
661     }
662   } else if (length < 0) {
663     THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
664   }
665 }
666 
667 // Replace the last '+' char with '/'.
668 static char* convert_hidden_name_to_java(Symbol* name) {
669   size_t name_len = name->utf8_length();
670   char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
671   name->as_klass_external_name(result, (int)name_len + 1);
672   for (int index = (int)name_len; index > 0; index--) {
673     if (result[index] == '+') {
674       result[index] = JVM_SIGNATURE_SLASH;
675       break;
676     }
677   }
678   return result;
679 }
680 
681 // In product mode, this function doesn't have virtual function calls so
682 // there might be some performance advantage to handling InstanceKlass here.
683 const char* Klass::external_name() const {
684   if (is_instance_klass()) {
685     const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
686     if (ik->is_hidden()) {
687       char* result = convert_hidden_name_to_java(name());
688       return result;
689     }
690   } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
691     char* result = convert_hidden_name_to_java(name());
692     return result;
693   }
694   if (name() == NULL)  return "<unknown>";
695   return name()->as_klass_external_name();
696 }
697 
698 const char* Klass::signature_name() const {
699   if (name() == NULL)  return "<unknown>";
700   if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
701     size_t name_len = name()->utf8_length();
702     char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
703     name()->as_C_string(result, (int)name_len + 1);
704     for (int index = (int)name_len; index > 0; index--) {
705       if (result[index] == '+') {
706         result[index] = JVM_SIGNATURE_DOT;
707         break;
708       }
709     }
710     return result;
711   }
712   return name()->as_C_string();
713 }
714 
715 const char* Klass::external_kind() const {
716   if (is_interface()) return "interface";
717   if (is_abstract()) return "abstract class";
718   return "class";
719 }
720 
721 int Klass::atomic_incr_biased_lock_revocation_count() {
722   return (int) Atomic::add(&_biased_lock_revocation_count, 1);
723 }
724 
725 // Unless overridden, jvmti_class_status has no flags set.
726 jint Klass::jvmti_class_status() const {
727   return 0;
728 }
729 
730 
731 // Printing
732 
733 void Klass::print_on(outputStream* st) const {
734   ResourceMark rm;
735   // print title
736   st->print("%s", internal_name());
737   print_address_on(st);
738   st->cr();
739 }
740 
741 #define BULLET  " - "
742 
743 // Caller needs ResourceMark
744 void Klass::oop_print_on(oop obj, outputStream* st) {
745   // print title
746   st->print_cr("%s ", internal_name());
747   obj->print_address_on(st);
748 
749   if (WizardMode) {
750      // print header
751      obj->mark().print_on(st);
752      st->cr();
753      st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
754      st->cr();
755   }
756 
757   // print class
758   st->print(BULLET"klass: ");
759   obj->klass()->print_value_on(st);
760   st->cr();
761 }
762 
763 void Klass::oop_print_value_on(oop obj, outputStream* st) {
764   // print title
765   ResourceMark rm;              // Cannot print in debug mode without this
766   st->print("%s", internal_name());
767   obj->print_address_on(st);
768 }
769 
770 // Verification
771 
772 void Klass::verify_on(outputStream* st) {
773 
774   // This can be expensive, but it is worth checking that this klass is actually
775   // in the CLD graph but not in production.
776   assert(Metaspace::contains((address)this), "Should be");
777 
778   guarantee(this->is_klass(),"should be klass");
779 
780   if (super() != NULL) {
781     guarantee(super()->is_klass(), "should be klass");
782   }
783   if (secondary_super_cache() != NULL) {
784     Klass* ko = secondary_super_cache();
785     guarantee(ko->is_klass(), "should be klass");
786   }
787   for ( uint i = 0; i < primary_super_limit(); i++ ) {
788     Klass* ko = _primary_supers[i];
789     if (ko != NULL) {
790       guarantee(ko->is_klass(), "should be klass");
791     }
792   }
793 
794   if (java_mirror_no_keepalive() != NULL) {
795     guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
796   }
797 }
798 
799 void Klass::oop_verify_on(oop obj, outputStream* st) {
800   guarantee(oopDesc::is_oop(obj),  "should be oop");
801   guarantee(obj->klass()->is_klass(), "klass field is not a klass");
802 }
803 
804 bool Klass::is_valid(Klass* k) {
805   if (!is_aligned(k, sizeof(MetaWord))) return false;
806   if ((size_t)k < os::min_page_size()) return false;
807 
808   if (!os::is_readable_range(k, k + 1)) return false;
809   if (!Metaspace::contains(k)) return false;
810 
811   if (!Symbol::is_valid(k->name())) return false;
812   return ClassLoaderDataGraph::is_valid(k->class_loader_data());
813 }
814 
815 Method* Klass::method_at_vtable(int index)  {
816 #ifndef PRODUCT
817   assert(index >= 0, "valid vtable index");
818   if (DebugVtables) {
819     verify_vtable_index(index);
820   }
821 #endif
822   return start_of_vtable()[index].method();
823 }
824 
825 
826 #ifndef PRODUCT
827 
828 bool Klass::verify_vtable_index(int i) {
829   int limit = vtable_length()/vtableEntry::size();
830   assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
831   return true;
832 }
833 
834 #endif // PRODUCT
835 
836 // Caller needs ResourceMark
837 // joint_in_module_of_loader provides an optimization if 2 classes are in
838 // the same module to succinctly print out relevant information about their
839 // module name and class loader's name_and_id for error messages.
840 // Format:
841 //   <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
842 //                      are in module <module-name>[@<version>]
843 //                      of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
844 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
845   assert(module() == class2->module(), "classes do not have the same module");
846   const char* class1_name = external_name();
847   size_t len = strlen(class1_name) + 1;
848 
849   const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
850   len += strlen(class2_description);
851 
852   len += strlen(" and ");
853 
854   char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
855 
856   // Just return the FQN if error when allocating string
857   if (joint_description == NULL) {
858     return class1_name;
859   }
860 
861   jio_snprintf(joint_description, len, "%s and %s",
862                class1_name,
863                class2_description);
864 
865   return joint_description;
866 }
867 
868 // Caller needs ResourceMark
869 // class_in_module_of_loader provides a standard way to include
870 // relevant information about a class, such as its module name as
871 // well as its class loader's name_and_id, in error messages and logging.
872 // Format:
873 //   <fully-qualified-external-class-name> is in module <module-name>[@<version>]
874 //                                         of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
875 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
876   // 1. fully qualified external name of class
877   const char* klass_name = external_name();
878   size_t len = strlen(klass_name) + 1;
879 
880   // 2. module name + @version
881   const char* module_name = "";
882   const char* version = "";
883   bool has_version = false;
884   bool module_is_named = false;
885   const char* module_name_phrase = "";
886   const Klass* bottom_klass = is_objArray_klass() ?
887                                 ObjArrayKlass::cast(this)->bottom_klass() : this;
888   if (bottom_klass->is_instance_klass()) {
889     ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
890     if (module->is_named()) {
891       module_is_named = true;
892       module_name_phrase = "module ";
893       module_name = module->name()->as_C_string();
894       len += strlen(module_name);
895       // Use version if exists and is not a jdk module
896       if (module->should_show_version()) {
897         has_version = true;
898         version = module->version()->as_C_string();
899         // Include stlen(version) + 1 for the "@"
900         len += strlen(version) + 1;
901       }
902     } else {
903       module_name = UNNAMED_MODULE;
904       len += UNNAMED_MODULE_LEN;
905     }
906   } else {
907     // klass is an array of primitives, module is java.base
908     module_is_named = true;
909     module_name_phrase = "module ";
910     module_name = JAVA_BASE_NAME;
911     len += JAVA_BASE_NAME_LEN;
912   }
913 
914   // 3. class loader's name_and_id
915   ClassLoaderData* cld = class_loader_data();
916   assert(cld != NULL, "class_loader_data should not be null");
917   const char* loader_name_and_id = cld->loader_name_and_id();
918   len += strlen(loader_name_and_id);
919 
920   // 4. include parent loader information
921   const char* parent_loader_phrase = "";
922   const char* parent_loader_name_and_id = "";
923   if (include_parent_loader &&
924       !cld->is_builtin_class_loader_data()) {
925     oop parent_loader = java_lang_ClassLoader::parent(class_loader());
926     ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
927     // The parent loader's ClassLoaderData could be null if it is
928     // a delegating class loader that has never defined a class.
929     // In this case the loader's name must be obtained via the parent loader's oop.
930     if (parent_cld == NULL) {
931       oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
932       if (cl_name_and_id != NULL) {
933         parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
934       }
935     } else {
936       parent_loader_name_and_id = parent_cld->loader_name_and_id();
937     }
938     parent_loader_phrase = ", parent loader ";
939     len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
940   }
941 
942   // Start to construct final full class description string
943   len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
944   len += strlen(module_name_phrase) + strlen(" of loader ");
945 
946   char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
947 
948   // Just return the FQN if error when allocating string
949   if (class_description == NULL) {
950     return klass_name;
951   }
952 
953   jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
954                klass_name,
955                (use_are) ? "are" : "is",
956                module_name_phrase,
957                module_name,
958                (has_version) ? "@" : "",
959                (has_version) ? version : "",
960                loader_name_and_id,
961                parent_loader_phrase,
962                parent_loader_name_and_id);
963 
964   return class_description;
965 }