1 /*
  2  * Copyright (c) 1997, 2025, 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.
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 23  */
 24 
 25 #include "cds/cdsConfig.hpp"
 26 #include "classfile/moduleEntry.hpp"
 27 #include "classfile/packageEntry.hpp"
 28 #include "classfile/symbolTable.hpp"
 29 #include "classfile/vmClasses.hpp"
 30 #include "classfile/vmSymbols.hpp"
 31 #include "gc/shared/collectedHeap.inline.hpp"
 32 #include "memory/iterator.inline.hpp"
 33 #include "memory/metadataFactory.hpp"
 34 #include "memory/metaspaceClosure.hpp"
 35 #include "memory/oopFactory.hpp"
 36 #include "memory/resourceArea.hpp"
 37 #include "memory/universe.hpp"
 38 #include "oops/arrayKlass.hpp"
 39 #include "oops/flatArrayKlass.hpp"
 40 #include "oops/instanceKlass.hpp"
 41 #include "oops/klass.inline.hpp"
 42 #include "oops/markWord.hpp"
 43 #include "oops/objArrayKlass.inline.hpp"
 44 #include "oops/objArrayOop.inline.hpp"
 45 #include "oops/oop.inline.hpp"
 46 #include "oops/refArrayKlass.hpp"
 47 #include "oops/symbol.hpp"
 48 #include "runtime/arguments.hpp"
 49 #include "runtime/handles.inline.hpp"
 50 #include "runtime/mutexLocker.hpp"
 51 #include "utilities/macros.hpp"
 52 
 53 ObjArrayKlass* ObjArrayKlass::allocate_klass(ClassLoaderData* loader_data, int n,
 54                                        Klass* k, Symbol* name, ArrayKlass::ArrayProperties props,
 55                                        TRAPS) {
 56   assert(ObjArrayKlass::header_size() <= InstanceKlass::header_size(),
 57       "array klasses must be same size as InstanceKlass");
 58 
 59   int size = ArrayKlass::static_size(ObjArrayKlass::header_size());
 60 
 61   return new (loader_data, size, THREAD) ObjArrayKlass(n, k, name, Kind, props, ArrayKlass::is_null_restricted(props) ? markWord::null_free_array_prototype() : markWord::prototype());
 62 }
 63 
 64 Symbol* ObjArrayKlass::create_element_klass_array_name(JavaThread* current, Klass* element_klass) {
 65   ResourceMark rm(current);
 66   char* name_str = element_klass->name()->as_C_string();
 67   int len = element_klass->name()->utf8_length();
 68   char* new_str = NEW_RESOURCE_ARRAY_IN_THREAD(current, char, len + 4);
 69   int idx = 0;
 70   new_str[idx++] = JVM_SIGNATURE_ARRAY;
 71   if (element_klass->is_instance_klass()) { // it could be an array or simple type
 72     new_str[idx++] = JVM_SIGNATURE_CLASS;
 73   }
 74   memcpy(&new_str[idx], name_str, len * sizeof(char));
 75   idx += len;
 76   if (element_klass->is_instance_klass()) {
 77     new_str[idx++] = JVM_SIGNATURE_ENDCLASS;
 78   }
 79   new_str[idx] = '\0';
 80   return SymbolTable::new_symbol(new_str);
 81 }
 82 
 83 
 84 ObjArrayKlass* ObjArrayKlass::allocate_objArray_klass(ClassLoaderData* loader_data,
 85                                                       int n, Klass* element_klass,  TRAPS) {
 86 
 87   // Eagerly allocate the direct array supertype.
 88   Klass* super_klass = nullptr;
 89   if (!Universe::is_bootstrapping() || vmClasses::Object_klass_is_loaded()) {
 90     assert(MultiArray_lock->holds_lock(THREAD), "must hold lock after bootstrapping");
 91     Klass* element_super = element_klass->super();
 92     if (element_super != nullptr) {
 93       // The element type has a direct super.  E.g., String[] has direct super of Object[].
 94       // Also, see if the element has secondary supertypes.
 95       // We need an array type for each before creating this array type.
 96       super_klass = element_super->array_klass(CHECK_NULL);
 97       const Array<Klass*>* element_supers = element_klass->secondary_supers();
 98       for (int i = element_supers->length() - 1; i >= 0; i--) {
 99         Klass* elem_super = element_supers->at(i);
100         elem_super->array_klass(CHECK_NULL);
101       }
102       // Fall through because inheritance is acyclic and we hold the global recursive lock to allocate all the arrays.
103     } else {
104       // The element type is already Object.  Object[] has direct super of Object.
105       super_klass = vmClasses::Object_klass();
106     }
107   }
108 
109   // Create type name for klass.
110   Symbol* name = create_element_klass_array_name(THREAD, element_klass);
111 
112   // Initialize instance variables
113   ObjArrayKlass* oak = ObjArrayKlass::allocate_klass(loader_data, n, element_klass, name, ArrayProperties::INVALID, CHECK_NULL);
114 
115   ModuleEntry* module = oak->module();
116   assert(module != nullptr, "No module entry for array");
117 
118   // Call complete_create_array_klass after all instance variables has been initialized.
119   ArrayKlass::complete_create_array_klass(oak, super_klass, module, CHECK_NULL);
120 
121   // Add all classes to our internal class loader list here,
122   // including classes in the bootstrap (null) class loader.
123   // Do this step after creating the mirror so that if the
124   // mirror creation fails, loaded_classes_do() doesn't find
125   // an array class without a mirror.
126   loader_data->add_class(oak);
127 
128   return oak;
129 }
130 
131 ObjArrayKlass::ObjArrayKlass(int n, Klass* element_klass, Symbol* name, KlassKind kind, ArrayKlass::ArrayProperties props, markWord mk) :
132 ArrayKlass(name, kind, props, mk) {
133   set_dimension(n);
134   set_element_klass(element_klass);
135   set_next_refined_klass_klass(nullptr);
136   set_properties(props);
137 
138   Klass* bk;
139   if (element_klass->is_objArray_klass()) {
140     bk = ObjArrayKlass::cast(element_klass)->bottom_klass();
141   } else {
142     assert(!element_klass->is_refArray_klass(), "Sanity");
143     bk = element_klass;
144   }
145   assert(bk != nullptr && (bk->is_instance_klass() || bk->is_typeArray_klass()), "invalid bottom klass");
146   set_bottom_klass(bk);
147   set_class_loader_data(bk->class_loader_data());
148 
149   if (element_klass->is_array_klass()) {
150     set_lower_dimension(ArrayKlass::cast(element_klass));
151   }
152 
153   int lh = array_layout_helper(T_OBJECT);
154   if (ArrayKlass::is_null_restricted(props)) {
155     assert(n == 1, "Bytecode does not support null-free multi-dim");
156     lh = layout_helper_set_null_free(lh);
157 #ifdef _LP64
158     assert(prototype_header().is_null_free_array(), "sanity");
159 #endif
160   }
161   set_layout_helper(lh);
162   assert(is_array_klass(), "sanity");
163   assert(is_objArray_klass(), "sanity");
164 }
165 
166 size_t ObjArrayKlass::oop_size(oop obj) const {
167   // In this assert, we cannot safely access the Klass* with compact headers,
168   // because size_given_klass() calls oop_size() on objects that might be
169   // concurrently forwarded, which would overwrite the Klass*.
170   assert(UseCompactObjectHeaders || obj->is_objArray(), "must be object array");
171   // return objArrayOop(obj)->object_size();
172   return obj->is_flatArray() ? flatArrayOop(obj)->object_size(layout_helper()) : refArrayOop(obj)->object_size();
173 }
174 
175 ArrayDescription ObjArrayKlass::array_layout_selection(Klass* element, ArrayProperties properties) {
176   // TODO FIXME: the layout selection should take the array size in consideration
177   // to avoid creation of arrays too big to be handled by the VM. See JDK-8233189
178   if (!UseArrayFlattening || element->is_array_klass() || element->is_identity_class() || element->is_abstract()) {
179     return ArrayDescription(RefArrayKlassKind, properties, LayoutKind::REFERENCE);
180   }
181   assert(element->is_final(), "Flat layouts below require monomorphic elements");
182   InlineKlass* vk = InlineKlass::cast(element);
183   if (is_null_restricted(properties)) {
184     if (is_non_atomic(properties)) {
185       // Null-restricted + non-atomic
186       if (vk->maybe_flat_in_array() && vk->has_non_atomic_layout()) {
187         return ArrayDescription(FlatArrayKlassKind, properties, LayoutKind::NON_ATOMIC_FLAT);
188       } else {
189         return ArrayDescription(RefArrayKlassKind, properties, LayoutKind::REFERENCE);
190       }
191     } else {
192       // Null-restricted + atomic
193       if (vk->maybe_flat_in_array() && vk->is_naturally_atomic() && vk->has_non_atomic_layout()) {
194         return ArrayDescription(FlatArrayKlassKind, properties, LayoutKind::NON_ATOMIC_FLAT);
195       } else if (vk->maybe_flat_in_array() && vk->has_atomic_layout()) {
196         return ArrayDescription(FlatArrayKlassKind, properties, LayoutKind::ATOMIC_FLAT);
197       } else {
198         return ArrayDescription(RefArrayKlassKind, properties, LayoutKind::REFERENCE);
199       }
200     }
201   } else {
202     // nullable implies atomic, so the non-atomic property is ignored
203     if (vk->maybe_flat_in_array() && vk->has_nullable_atomic_layout()) {
204       return ArrayDescription(FlatArrayKlassKind, properties, LayoutKind::NULLABLE_ATOMIC_FLAT);
205     } else {
206       return ArrayDescription(RefArrayKlassKind, properties, LayoutKind::REFERENCE);
207     }
208   }
209 }
210 
211 ObjArrayKlass* ObjArrayKlass::allocate_klass_with_properties(ArrayKlass::ArrayProperties props, TRAPS) {
212   ObjArrayKlass* ak = nullptr;
213   ArrayDescription ad = ObjArrayKlass::array_layout_selection(element_klass(), props);
214   switch (ad._kind) {
215     case Klass::RefArrayKlassKind: {
216       ak = RefArrayKlass::allocate_refArray_klass(class_loader_data(), dimension(), element_klass(), props, CHECK_NULL);
217       break;
218     }
219     case Klass::FlatArrayKlassKind: {
220       assert(dimension() == 1, "Flat arrays can only be dimension 1 arrays");
221       ak = FlatArrayKlass::allocate_klass(element_klass(), props, ad._layout_kind, CHECK_NULL);
222       break;
223     }
224     default:
225       ShouldNotReachHere();
226   }
227   return ak;
228 }
229 
230 objArrayOop ObjArrayKlass::allocate_instance(int length, ArrayProperties props, TRAPS) {
231   check_array_allocation_length(length, arrayOopDesc::max_array_length(T_OBJECT), CHECK_NULL);
232   ObjArrayKlass* ak = klass_with_properties(props, THREAD);
233   size_t size = 0;
234   switch(ak->kind()) {
235     case Klass::RefArrayKlassKind:
236       size = refArrayOopDesc::object_size(length);
237       break;
238     case Klass::FlatArrayKlassKind:
239       size = flatArrayOopDesc::object_size(ak->layout_helper(), length);
240       break;
241     default:
242       ShouldNotReachHere();
243   }
244   assert(size != 0, "Sanity check");
245   objArrayOop array = (objArrayOop)Universe::heap()->array_allocate(
246     ak, size, length,
247     /* do_zero */ true, CHECK_NULL);
248   assert(array->is_refArray() || array->is_flatArray(), "Must be");
249   objArrayHandle array_h(THREAD, array);
250   return array_h();
251 }
252 
253 oop ObjArrayKlass::multi_allocate(int rank, jint* sizes, TRAPS) {
254   int length = *sizes;
255   ArrayKlass* ld_klass = lower_dimension();
256   // If length < 0 allocate will throw an exception.
257   ObjArrayKlass* oak = klass_with_properties(ArrayProperties::DEFAULT, CHECK_NULL);
258   assert(oak->is_refArray_klass() || oak->is_flatArray_klass(), "Must be");
259   objArrayOop array = oak->allocate_instance(length, ArrayProperties::DEFAULT, CHECK_NULL);
260   objArrayHandle h_array (THREAD, array);
261   if (rank > 1) {
262     if (length != 0) {
263       for (int index = 0; index < length; index++) {
264         oop sub_array = ld_klass->multi_allocate(rank-1, &sizes[1], CHECK_NULL);
265         h_array->obj_at_put(index, sub_array);
266       }
267     } else {
268       // Since this array dimension has zero length, nothing will be
269       // allocated, however the lower dimension values must be checked
270       // for illegal values.
271       for (int i = 0; i < rank - 1; ++i) {
272         sizes += 1;
273         if (*sizes < 0) {
274           THROW_MSG_NULL(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", *sizes));
275         }
276       }
277     }
278   }
279   return h_array();
280 }
281 
282 void ObjArrayKlass::copy_array(arrayOop s, int src_pos, arrayOop d,
283                                int dst_pos, int length, TRAPS) {
284   assert(s->is_objArray(), "must be obj array");
285 
286   if (UseArrayFlattening) {
287     if (d->is_flatArray()) {
288       FlatArrayKlass::cast(d->klass())->copy_array(s, src_pos, d, dst_pos, length, THREAD);
289       return;
290     }
291     if (s->is_flatArray()) {
292       FlatArrayKlass::cast(s->klass())->copy_array(s, src_pos, d, dst_pos, length, THREAD);
293       return;
294     }
295   }
296 
297   assert(s->is_refArray() && d->is_refArray(), "Must be");
298   RefArrayKlass::cast(s->klass())->copy_array(s, src_pos, d, dst_pos, length, THREAD);
299 }
300 
301 bool ObjArrayKlass::can_be_primary_super_slow() const {
302   if (!bottom_klass()->can_be_primary_super())
303     // array of interfaces
304     return false;
305   else
306     return Klass::can_be_primary_super_slow();
307 }
308 
309 GrowableArray<Klass*>* ObjArrayKlass::compute_secondary_supers(int num_extra_slots,
310                                                                Array<InstanceKlass*>* transitive_interfaces) {
311   assert(transitive_interfaces == nullptr, "sanity");
312   // interfaces = { cloneable_klass, serializable_klass, elemSuper[], ... };
313   const Array<Klass*>* elem_supers = element_klass()->secondary_supers();
314   int num_elem_supers = elem_supers == nullptr ? 0 : elem_supers->length();
315   int num_secondaries = num_extra_slots + 2 + num_elem_supers;
316   if (num_secondaries == 2) {
317     // Must share this for correct bootstrapping!
318     set_secondary_supers(Universe::the_array_interfaces_array(),
319                          Universe::the_array_interfaces_bitmap());
320     return nullptr;
321   } else {
322     GrowableArray<Klass*>* secondaries = new GrowableArray<Klass*>(num_elem_supers+2);
323     secondaries->push(vmClasses::Cloneable_klass());
324     secondaries->push(vmClasses::Serializable_klass());
325     for (int i = 0; i < num_elem_supers; i++) {
326       Klass* elem_super = elem_supers->at(i);
327       Klass* array_super = elem_super->array_klass_or_null();
328       assert(array_super != nullptr, "must already have been created");
329       secondaries->push(array_super);
330     }
331     return secondaries;
332   }
333 }
334 
335 void ObjArrayKlass::initialize(TRAPS) {
336   bottom_klass()->initialize(THREAD);  // dispatches to either InstanceKlass or TypeArrayKlass
337 }
338 
339 void ObjArrayKlass::metaspace_pointers_do(MetaspaceClosure* it) {
340   ArrayKlass::metaspace_pointers_do(it);
341   it->push(&_element_klass);
342   it->push(&_bottom_klass);
343   if (_next_refined_array_klass != nullptr && !CDSConfig::is_dumping_dynamic_archive()) {
344     it->push(&_next_refined_array_klass);
345   }
346 }
347 
348 #if INCLUDE_CDS
349 void ObjArrayKlass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
350   ArrayKlass::restore_unshareable_info(loader_data, protection_domain, CHECK);
351   if (_next_refined_array_klass != nullptr) {
352     _next_refined_array_klass->restore_unshareable_info(loader_data, protection_domain, CHECK);
353   }
354 }
355 
356 void ObjArrayKlass::remove_unshareable_info() {
357   ArrayKlass::remove_unshareable_info();
358   if (_next_refined_array_klass != nullptr && !CDSConfig::is_dumping_dynamic_archive()) {
359     _next_refined_array_klass->remove_unshareable_info();
360   } else {
361     _next_refined_array_klass = nullptr;
362   }
363 }
364 
365 void ObjArrayKlass::remove_java_mirror() {
366   ArrayKlass::remove_java_mirror();
367   if (_next_refined_array_klass != nullptr && !CDSConfig::is_dumping_dynamic_archive()) {
368     _next_refined_array_klass->remove_java_mirror();
369   }
370 }
371 #endif // INCLUDE_CDS
372 
373 u2 ObjArrayKlass::compute_modifier_flags() const {
374   // The modifier for an objectArray is the same as its element
375   assert (element_klass() != nullptr, "should be initialized");
376 
377   // Return the flags of the bottom element type.
378   u2 element_flags = bottom_klass()->compute_modifier_flags();
379 
380   int identity_flag = (Arguments::enable_preview()) ? JVM_ACC_IDENTITY : 0;
381 
382   return (element_flags & (JVM_ACC_PUBLIC | JVM_ACC_PRIVATE | JVM_ACC_PROTECTED))
383                         | (identity_flag | JVM_ACC_ABSTRACT | JVM_ACC_FINAL);
384 }
385 
386 ModuleEntry* ObjArrayKlass::module() const {
387   assert(bottom_klass() != nullptr, "ObjArrayKlass returned unexpected null bottom_klass");
388   // The array is defined in the module of its bottom class
389   return bottom_klass()->module();
390 }
391 
392 PackageEntry* ObjArrayKlass::package() const {
393   assert(bottom_klass() != nullptr, "ObjArrayKlass returned unexpected null bottom_klass");
394   return bottom_klass()->package();
395 }
396 
397 ObjArrayKlass* ObjArrayKlass::klass_with_properties(ArrayKlass::ArrayProperties props, TRAPS) {
398   assert(props != ArrayProperties::INVALID, "Sanity check");
399 
400   if (properties() == props) {
401     assert(is_refArray_klass() || is_flatArray_klass(), "Must be a concrete array klass");
402     return this;
403   }
404 
405   ObjArrayKlass* ak = next_refined_array_klass_acquire();
406   if (ak == nullptr) {
407     // Ensure atomic creation of refined array klasses
408     RecursiveLocker rl(MultiArray_lock, THREAD);
409 
410     if (next_refined_array_klass() == nullptr) {
411       ObjArrayKlass* first = this;
412       if (!is_refArray_klass() && !is_flatArray_klass() && props != ArrayKlass::ArrayProperties::DEFAULT) {
413         // Make sure that the first entry in the linked list is always the default refined klass because
414         // C2 relies on this for a fast lookup (see LibraryCallKit::load_default_refined_array_klass).
415         first = allocate_klass_with_properties(ArrayKlass::ArrayProperties::DEFAULT, THREAD);
416         release_set_next_refined_klass(first);
417       }
418       ak = allocate_klass_with_properties(props, THREAD);
419       first->release_set_next_refined_klass(ak);
420     }
421   }
422 
423   ak = next_refined_array_klass();
424   assert(ak != nullptr, "should be set");
425   THREAD->check_possible_safepoint();
426   return ak->klass_with_properties(props, THREAD); // why not CHECK_NULL ?
427 }
428 
429 
430 // Printing
431 
432 void ObjArrayKlass::print_on(outputStream* st) const {
433 #ifndef PRODUCT
434   Klass::print_on(st);
435   st->print(" - element klass: ");
436   element_klass()->print_value_on(st);
437   st->cr();
438 #endif //PRODUCT
439 }
440 
441 void ObjArrayKlass::print_value_on(outputStream* st) const {
442   assert(is_klass(), "must be klass");
443 
444   element_klass()->print_value_on(st);
445   st->print("[]");
446 }
447 
448 #ifndef PRODUCT
449 
450 void ObjArrayKlass::oop_print_on(oop obj, outputStream* st) {
451   ShouldNotReachHere();
452 }
453 
454 #endif //PRODUCT
455 
456 void ObjArrayKlass::oop_print_value_on(oop obj, outputStream* st) {
457   ShouldNotReachHere();
458 }
459 
460 const char* ObjArrayKlass::internal_name() const {
461   return external_name();
462 }
463 
464 
465 // Verification
466 
467 void ObjArrayKlass::verify_on(outputStream* st) {
468   ArrayKlass::verify_on(st);
469   guarantee(element_klass()->is_klass(), "should be klass");
470   guarantee(bottom_klass()->is_klass(), "should be klass");
471   Klass* bk = bottom_klass();
472   guarantee(bk->is_instance_klass() || bk->is_typeArray_klass() || bk->is_flatArray_klass(),
473             "invalid bottom klass");
474 }
475 
476 void ObjArrayKlass::oop_verify_on(oop obj, outputStream* st) {
477   ArrayKlass::oop_verify_on(obj, st);
478   guarantee(obj->is_objArray(), "must be objArray");
479   guarantee(obj->is_null_free_array() || (!is_null_free_array_klass()), "null-free klass but not object");
480   objArrayOop oa = objArrayOop(obj);
481   for(int index = 0; index < oa->length(); index++) {
482     guarantee(oopDesc::is_oop_or_null(oa->obj_at(index)), "should be oop");
483   }
484 }