1 /*
2 * Copyright (c) 1997, 2026, 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 "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/arrayOop.inline.hpp"
40 #include "oops/flatArrayKlass.hpp"
41 #include "oops/inlineKlass.hpp"
42 #include "oops/instanceKlass.hpp"
43 #include "oops/klass.inline.hpp"
44 #include "oops/layoutKind.hpp"
45 #include "oops/markWord.hpp"
46 #include "oops/objArrayKlass.inline.hpp"
47 #include "oops/objArrayOop.inline.hpp"
48 #include "oops/oop.inline.hpp"
49 #include "oops/oopCast.inline.hpp"
50 #include "oops/refArrayKlass.hpp"
51 #include "oops/symbol.hpp"
52 #include "runtime/arguments.hpp"
53 #include "runtime/handles.inline.hpp"
54 #include "runtime/mutexLocker.hpp"
55 #include "utilities/macros.hpp"
56
57 ObjArrayKlass* ObjArrayKlass::allocate_klass(ClassLoaderData* loader_data, int n,
58 Klass* k, Symbol* name,
59 ArrayProperties props, TRAPS) {
60 assert(ObjArrayKlass::header_size() <= InstanceKlass::header_size(),
61 "array klasses must be same size as InstanceKlass");
62
63 int size = ArrayKlass::static_size(ObjArrayKlass::header_size());
64
65 return new (loader_data, size, THREAD) ObjArrayKlass(n, k, name, Kind, props);
66 }
67
68 Symbol* ObjArrayKlass::create_element_klass_array_name(JavaThread* current, Klass* element_klass) {
69 ResourceMark rm(current);
70 char* name_str = element_klass->name()->as_C_string();
71 int len = element_klass->name()->utf8_length();
72 char* new_str = NEW_RESOURCE_ARRAY_IN_THREAD(current, char, len + 4);
73 int idx = 0;
74 new_str[idx++] = JVM_SIGNATURE_ARRAY;
75 if (element_klass->is_instance_klass()) { // it could be an array or simple type
76 new_str[idx++] = JVM_SIGNATURE_CLASS;
77 }
78 memcpy(&new_str[idx], name_str, len * sizeof(char));
79 idx += len;
80 if (element_klass->is_instance_klass()) {
81 new_str[idx++] = JVM_SIGNATURE_ENDCLASS;
82 }
83 new_str[idx] = '\0';
84 return SymbolTable::new_symbol(new_str);
85 }
86
87
88 ObjArrayKlass* ObjArrayKlass::allocate_objArray_klass(ClassLoaderData* loader_data,
89 int n, Klass* element_klass, TRAPS) {
90
91 // Eagerly allocate the direct array supertype.
92 Klass* super_klass = nullptr;
93 if (!Universe::is_bootstrapping() || vmClasses::Object_klass_is_loaded()) {
94 assert(MultiArray_lock->holds_lock(THREAD), "must hold lock after bootstrapping");
95 Klass* element_super = element_klass->super();
96 if (element_super != nullptr) {
97 // The element type has a direct super. E.g., String[] has direct super of Object[].
98 // Also, see if the element has secondary supertypes.
99 // We need an array type for each before creating this array type.
100 super_klass = element_super->array_klass(CHECK_NULL);
101 const Array<Klass*>* element_supers = element_klass->secondary_supers();
102 for (int i = element_supers->length() - 1; i >= 0; i--) {
103 Klass* elem_super = element_supers->at(i);
104 elem_super->array_klass(CHECK_NULL);
105 }
106 // Fall through because inheritance is acyclic and we hold the global recursive lock to allocate all the arrays.
107 } else {
108 // The element type is already Object. Object[] has direct super of Object.
109 super_klass = vmClasses::Object_klass();
110 }
111 }
112
113 // Create type name for klass.
114 Symbol* name = create_element_klass_array_name(THREAD, element_klass);
115
116 // Initialize instance variables
117 ObjArrayKlass* oak = ObjArrayKlass::allocate_klass(loader_data, n, element_klass, name, ArrayProperties::Invalid(), CHECK_NULL);
118
119 ModuleEntry* module = oak->module();
120 assert(module != nullptr, "No module entry for array");
121
122 // Call complete_create_array_klass after all instance variables has been initialized.
123 ArrayKlass::complete_create_array_klass(oak, super_klass, module, CHECK_NULL);
124
125 // Add all classes to our internal class loader list here,
126 // including classes in the bootstrap (null) class loader.
127 // Do this step after creating the mirror so that if the
128 // mirror creation fails, loaded_classes_do() doesn't find
129 // an array class without a mirror.
130 loader_data->add_class(oak);
131
132 return oak;
133 }
134
135 static Klass* calculate_bottom_klass(Klass* element_klass) {
136 Klass* bk;
137 if (element_klass->is_objArray_klass()) {
138 assert(!element_klass->is_refined_objArray_klass(), "no such mechanism yet");
139 bk = ObjArrayKlass::cast(element_klass)->bottom_klass();
140 } else {
141 assert(!element_klass->is_refArray_klass(), "Sanity");
142 bk = element_klass;
143 }
144
145 assert(bk != nullptr, "Sanity");
146 assert(bk->is_instance_klass() || bk->is_typeArray_klass(), "invalid bottom klass");
147
148 return bk;
149 }
150
151 ObjArrayKlass::ObjArrayKlass(int n, Klass* element_klass, Symbol* name, KlassKind kind, ArrayProperties props)
152 : ArrayKlass(n, name, kind, props),
153 _element_klass(element_klass),
154 _bottom_klass(calculate_bottom_klass(element_klass)),
155 _next_refined_array_klass(nullptr) {
156
157 set_class_loader_data(_bottom_klass->class_loader_data());
158
159 if (element_klass->is_array_klass()) {
160 set_lower_dimension(ArrayKlass::cast(element_klass));
161 }
162
163 int lh = array_layout_helper(T_OBJECT);
164 if (props.is_null_restricted()) {
165 assert(n == 1, "Bytecode does not support null-free multi-dim");
166 lh = layout_helper_set_null_free(lh);
167 #ifdef _LP64
168 assert(prototype_header().is_null_free_array(), "sanity");
169 #endif
170 }
171 set_layout_helper(lh);
172 assert(is_array_klass(), "sanity");
173 assert(is_objArray_klass(), "sanity");
174 }
175
176 size_t ObjArrayKlass::oop_size(oop obj) const {
177 ShouldNotReachHere();
178 }
179
180 ArrayDescription ObjArrayKlass::array_layout_selection(Klass* element, ArrayProperties props) {
181 // TODO FIXME: the layout selection should take the array size in consideration
182 // to avoid creation of arrays too big to be handled by the VM. See JDK-8233189
183 if (!UseArrayFlattening || element->is_array_klass() || element->is_identity_class() || element->is_abstract()) {
184 return ArrayDescription(RefArrayKlassKind, props, LayoutKind::REFERENCE);
185 }
186 InlineKlass* vk = InlineKlass::cast(element);
187 if (!vk->maybe_flat_in_array()) {
188 return ArrayDescription(RefArrayKlassKind, props, LayoutKind::REFERENCE);
189 }
190
191 assert(vk->is_final(), "Flat layouts below require monomorphic elements");
192 if (props.is_null_restricted()) {
193 if (props.is_non_atomic()) {
194 // Null-restricted + non-atomic
195 if (vk->has_null_free_non_atomic_layout()) {
196 return ArrayDescription(FlatArrayKlassKind, props, LayoutKind::NULL_FREE_NON_ATOMIC_FLAT);
197 } else if (vk->has_null_free_atomic_layout()) {
198 return ArrayDescription(FlatArrayKlassKind, props, LayoutKind::NULL_FREE_ATOMIC_FLAT);
199 } else {
200 return ArrayDescription(RefArrayKlassKind, props, LayoutKind::REFERENCE);
201 }
202 } else {
203 // Null-restricted + atomic
204 if (vk->is_naturally_atomic() && vk->has_null_free_non_atomic_layout()) {
205 return ArrayDescription(FlatArrayKlassKind, props, LayoutKind::NULL_FREE_NON_ATOMIC_FLAT);
206 } else if (vk->has_null_free_atomic_layout()) {
207 return ArrayDescription(FlatArrayKlassKind, props, LayoutKind::NULL_FREE_ATOMIC_FLAT);
208 } else {
209 return ArrayDescription(RefArrayKlassKind, props, LayoutKind::REFERENCE);
210 }
211 }
212 } else {
213 // nullable implies atomic, so the non-atomic property is ignored
214 if (vk->has_nullable_atomic_layout()) {
215 return ArrayDescription(FlatArrayKlassKind, props, LayoutKind::NULLABLE_ATOMIC_FLAT);
216 } else {
217 return ArrayDescription(RefArrayKlassKind, props, LayoutKind::REFERENCE);
218 }
219 }
220 }
221
222 ObjArrayKlass* ObjArrayKlass::allocate_klass_from_description(ArrayDescription ad, TRAPS) {
223 assert(ad._properties.is_valid(), "Sanity check");
224 assert(ad._properties.is_null_restricted() || !ad._properties.is_non_atomic(), "only null-restricted array can be non-atomic");
225
226 switch (ad._kind) {
227 case Klass::RefArrayKlassKind:
228 return RefArrayKlass::allocate_refArray_klass(class_loader_data(), dimension(), element_klass(), ad._properties, CHECK_NULL);
229
230 case Klass::FlatArrayKlassKind:
231 assert(dimension() == 1, "Flat arrays can only be dimension 1 arrays");
232 return FlatArrayKlass::allocate_klass(element_klass(), ad._properties, ad._layout_kind, CHECK_NULL);
233
234 default:
235 ShouldNotReachHere();
236 }
237 }
238
239 objArrayOop ObjArrayKlass::allocate_instance(int length, ArrayProperties props, TRAPS) {
240 check_array_allocation_length(length, arrayOopDesc::max_array_length(T_OBJECT), CHECK_NULL);
241 ObjArrayKlass* ak = klass_with_properties(props, CHECK_NULL);
242 switch (ak->kind()) {
243 case Klass::RefArrayKlassKind:
244 return RefArrayKlass::cast(ak)->allocate_instance(length, CHECK_NULL);
245
246 case Klass::FlatArrayKlassKind:
247 return FlatArrayKlass::cast(ak)->allocate_instance(length, CHECK_NULL);
248
249 default:
250 ShouldNotReachHere();
251 }
252 }
253
254 oop ObjArrayKlass::multi_allocate(int rank, jint* sizes, TRAPS) {
255 int length = *sizes;
256 ArrayKlass* ld_klass = lower_dimension();
257 // If length < 0 allocate will throw an exception.
258 objArrayOop array = allocate_instance(length, ArrayProperties::Default(), CHECK_NULL);
259 assert(array->is_refined_objArray(), "Must be");
260
261 objArrayHandle h_array(THREAD, array);
262 if (rank > 1) {
263 if (length != 0) {
264 for (int index = 0; index < length; index++) {
265 oop sub_array = ld_klass->multi_allocate(rank - 1, &sizes[1], CHECK_NULL);
266 h_array->obj_at_put(index, sub_array);
267 }
268 } else {
269 // Since this array dimension has zero length, nothing will be
270 // allocated, however the lower dimension values must be checked
271 // for illegal values.
272 for (int i = 0; i < rank - 1; ++i) {
273 sizes += 1;
274 if (*sizes < 0) {
275 THROW_MSG_NULL(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", *sizes));
276 }
277 }
278 }
279 }
280 return h_array();
281 }
282
283 void ObjArrayKlass::copy_array(arrayOop s, int src_pos, arrayOop d,
284 int dst_pos, int length, TRAPS) {
285 ShouldNotReachHere();
286 }
287
288 bool ObjArrayKlass::can_be_primary_super_slow() const {
289 if (!bottom_klass()->can_be_primary_super())
290 // array of interfaces
291 return false;
292 else
293 return Klass::can_be_primary_super_slow();
294 }
295
296 GrowableArray<Klass*>* ObjArrayKlass::compute_secondary_supers(int num_extra_slots,
297 Array<InstanceKlass*>* transitive_interfaces) {
298 assert(transitive_interfaces == nullptr, "sanity");
299 // interfaces = { cloneable_klass, serializable_klass, elemSuper[], ... };
300 const Array<Klass*>* elem_supers = element_klass()->secondary_supers();
301 int num_elem_supers = elem_supers == nullptr ? 0 : elem_supers->length();
302 int num_secondaries = num_extra_slots + 2 + num_elem_supers;
303 if (num_secondaries == 2) {
304 // Must share this for correct bootstrapping!
305 set_secondary_supers(Universe::the_array_interfaces_array(),
306 Universe::the_array_interfaces_bitmap());
307 return nullptr;
308 } else {
309 GrowableArray<Klass*>* secondaries = new GrowableArray<Klass*>(num_elem_supers+2);
310 secondaries->push(vmClasses::Cloneable_klass());
311 secondaries->push(vmClasses::Serializable_klass());
312 for (int i = 0; i < num_elem_supers; i++) {
313 Klass* elem_super = elem_supers->at(i);
314 Klass* array_super = elem_super->array_klass_or_null();
315 assert(array_super != nullptr, "must already have been created");
316 secondaries->push(array_super);
317 }
318 return secondaries;
319 }
320 }
321
322 void ObjArrayKlass::initialize(TRAPS) {
323 bottom_klass()->initialize(THREAD); // dispatches to either InstanceKlass or TypeArrayKlass
324 }
325
326 void ObjArrayKlass::metaspace_pointers_do(MetaspaceClosure* it) {
327 ArrayKlass::metaspace_pointers_do(it);
328 it->push(&_element_klass);
329 it->push(&_bottom_klass);
330 if (_next_refined_array_klass != nullptr && !CDSConfig::is_dumping_dynamic_archive()) {
331 it->push(&_next_refined_array_klass);
332 }
333 }
334
335 #if INCLUDE_CDS
336 void ObjArrayKlass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
337 ArrayKlass::restore_unshareable_info(loader_data, protection_domain, CHECK);
338 if (_next_refined_array_klass != nullptr) {
339 _next_refined_array_klass->restore_unshareable_info(loader_data, protection_domain, CHECK);
340 }
341 }
342
343 void ObjArrayKlass::remove_unshareable_info() {
344 ArrayKlass::remove_unshareable_info();
345 if (_next_refined_array_klass != nullptr && !CDSConfig::is_dumping_dynamic_archive()) {
346 _next_refined_array_klass->remove_unshareable_info();
347 } else {
348 _next_refined_array_klass = nullptr;
349 }
350 }
351
352 void ObjArrayKlass::remove_java_mirror() {
353 ArrayKlass::remove_java_mirror();
354 if (_next_refined_array_klass != nullptr && !CDSConfig::is_dumping_dynamic_archive()) {
355 _next_refined_array_klass->remove_java_mirror();
356 }
357 }
358 #endif // INCLUDE_CDS
359
360 u2 ObjArrayKlass::compute_modifier_flags() const {
361 // The modifier for an objectArray is the same as its element
362 assert (element_klass() != nullptr, "should be initialized");
363
364 // Return the flags of the bottom element type.
365 u2 element_flags = bottom_klass()->compute_modifier_flags();
366
367 int identity_flag = (Arguments::is_valhalla_enabled()) ? JVM_ACC_IDENTITY : 0;
368
369 return (element_flags & (JVM_ACC_PUBLIC | JVM_ACC_PRIVATE | JVM_ACC_PROTECTED))
370 | (identity_flag | JVM_ACC_ABSTRACT | JVM_ACC_FINAL);
371 }
372
373 ModuleEntry* ObjArrayKlass::module() const {
374 assert(bottom_klass() != nullptr, "ObjArrayKlass returned unexpected null bottom_klass");
375 // The array is defined in the module of its bottom class
376 return bottom_klass()->module();
377 }
378
379 PackageEntry* ObjArrayKlass::package() const {
380 assert(bottom_klass() != nullptr, "ObjArrayKlass returned unexpected null bottom_klass");
381 return bottom_klass()->package();
382 }
383
384 ObjArrayKlass* ObjArrayKlass::klass_with_properties(ArrayProperties props, TRAPS) {
385 assert(props.is_valid(), "Sanity check");
386 ArrayDescription ad = array_layout_selection(element_klass(), props);
387
388 return klass_from_description(ad, THREAD);
389 }
390
391 ObjArrayKlass* ObjArrayKlass::klass_from_description(ArrayDescription ad, TRAPS) {
392 element_klass()->validate_array_description(ad);
393
394 const ArrayProperties props = ad._properties;
395
396 if (properties() == props && kind() == ad._kind) {
397 assert(is_refined_objArray_klass(), "Must be a refined array klass");
398 return this;
399 }
400
401 ObjArrayKlass* ak = next_refined_array_klass_acquire();
402 if (ak == nullptr) {
403 // Ensure atomic creation of refined array klasses
404 RecursiveLocker rl(MultiArray_lock, THREAD);
405
406 if (next_refined_array_klass() == nullptr) {
407 ObjArrayKlass* first = this;
408 if (is_unrefined_objArray_klass() && props != ArrayProperties::Default()) {
409 assert(props.is_valid(), "must be");
410 // Make sure that the first entry in the linked list is always the default refined klass because
411 // C2 relies on this for a fast lookup (see LibraryCallKit::load_default_refined_array_klass).
412 ArrayDescription default_ad = array_layout_selection(element_klass(), ArrayProperties::Default());
413 first = allocate_klass_from_description(default_ad, CHECK_NULL);
414 release_set_next_refined_klass(first);
415 }
416 ak = allocate_klass_from_description(ad, CHECK_NULL);
417 first->release_set_next_refined_klass(ak);
418 }
419 }
420
421 ObjArrayKlass* next_ak = next_refined_array_klass();
422 assert(next_ak != nullptr, "should be set");
423 THREAD->check_possible_safepoint();
424 return next_ak->klass_from_description(ad, THREAD);
425 }
426
427 // Iterate the linked list of refined array klasses
428 bool ObjArrayKlass::find_refined_array_klass(ObjArrayKlass* k) {
429 assert(k->is_refined_objArray_klass(), "must be");
430 ObjArrayKlass* curr = this;
431 while (curr != nullptr) {
432 if (curr == k) {
433 return true;
434 }
435 curr = curr->next_refined_array_klass();
436 }
437 return false;
438 }
439
440 // Printing
441
442 void ObjArrayKlass::print_on(outputStream* st) const {
443 #ifndef PRODUCT
444 Klass::print_on(st);
445 st->print(" - element klass: ");
446 element_klass()->print_value_on(st);
447 st->cr();
448 #endif //PRODUCT
449 }
450
451 void ObjArrayKlass::print_value_on(outputStream* st) const {
452 assert(is_klass(), "must be klass");
453
454 element_klass()->print_value_on(st);
455 st->print("[]");
456 }
457
458 #ifndef PRODUCT
459
460 void ObjArrayKlass::oop_print_on(oop obj, outputStream* st) {
461 ShouldNotReachHere();
462 }
463
464 #endif //PRODUCT
465
466 void ObjArrayKlass::oop_print_value_on(oop obj, outputStream* st) {
467 ShouldNotReachHere();
468 }
469
470 const char* ObjArrayKlass::internal_name() const {
471 return external_name();
472 }
473
474
475 // Verification
476
477 void ObjArrayKlass::verify_on(outputStream* st) {
478 ArrayKlass::verify_on(st);
479 guarantee(element_klass()->is_klass(), "should be klass");
480 guarantee(bottom_klass()->is_klass(), "should be klass");
481 Klass* bk = bottom_klass();
482 guarantee(bk->is_instance_klass() || bk->is_typeArray_klass(),
483 "invalid bottom klass");
484 }
485
486 void ObjArrayKlass::oop_verify_on(oop obj, outputStream* st) {
487 ArrayKlass::oop_verify_on(obj, st);
488 guarantee(is_refined_objArray_klass(), "Must be called with refined obj array klass");
489 guarantee(obj->is_objArray(), "must be objArray");
490 guarantee(oop_cast<objArrayOop>(obj)->is_null_free_array() || (!is_null_free_array_klass()),
491 "null-free klass but not object");
492 }