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