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 "cds/metaspaceShared.hpp"
 27 #include "classfile/javaClasses.hpp"
 28 #include "classfile/moduleEntry.hpp"
 29 #include "classfile/vmClasses.hpp"
 30 #include "classfile/vmSymbols.hpp"
 31 #include "gc/shared/collectedHeap.inline.hpp"
 32 #include "jvmtifiles/jvmti.h"
 33 #include "memory/metaspaceClosure.hpp"
 34 #include "memory/resourceArea.hpp"
 35 #include "memory/universe.hpp"
 36 #include "oops/arrayKlass.inline.hpp"
 37 #include "oops/arrayOop.hpp"
 38 #include "oops/instanceKlass.hpp"
 39 #include "oops/klass.inline.hpp"
 40 #include "oops/objArrayOop.hpp"
 41 #include "oops/oop.inline.hpp"
 42 #include "runtime/handles.inline.hpp"
 43 
 44 void* ArrayKlass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
 45   return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, true, THREAD);
 46 }
 47 
 48 ArrayKlass::ArrayKlass() {
 49   assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for CDS");
 50 }
 51 
 52 int ArrayKlass::static_size(int header_size) {
 53   // size of an array klass object
 54   assert(header_size <= InstanceKlass::header_size(), "bad header size");
 55   // If this assert fails, see comments in base_create_array_klass.
 56   header_size = InstanceKlass::header_size();
 57   int vtable_len = Universe::base_vtable_size();
 58   int size = header_size + vtable_len;
 59   return align_metadata_size(size);
 60 }
 61 
 62 
 63 InstanceKlass* ArrayKlass::java_super() const {
 64   if (super() == nullptr)  return nullptr;  // bootstrap case
 65   // Array klasses have primary supertypes which are not reported to Java.
 66   // Example super chain:  String[][] -> Object[][] -> Object[] -> Object
 67   return vmClasses::Object_klass();
 68 }
 69 
 70 
 71 oop ArrayKlass::multi_allocate(int rank, jint* sizes, TRAPS) {
 72   ShouldNotReachHere();
 73   return nullptr;
 74 }
 75 
 76 // find field according to JVM spec 5.4.3.2, returns the klass in which the field is defined
 77 Klass* ArrayKlass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
 78   // There are no fields in an array klass but look to the super class (Object)
 79   assert(super(), "super klass must be present");
 80   return super()->find_field(name, sig, fd);
 81 }
 82 
 83 Method* ArrayKlass::uncached_lookup_method(const Symbol* name,
 84                                            const Symbol* signature,
 85                                            OverpassLookupMode overpass_mode,
 86                                            PrivateLookupMode private_mode) const {
 87   // There are no methods in an array klass but the super class (Object) has some
 88   assert(super(), "super klass must be present");
 89   // Always ignore overpass methods in superclasses, although technically the
 90   // super klass of an array, (j.l.Object) should not have
 91   // any overpass methods present.
 92   return super()->uncached_lookup_method(name, signature, OverpassLookupMode::skip, private_mode);
 93 }
 94 
 95 ArrayKlass::ArrayKlass(Symbol* name, KlassKind kind) :
 96   Klass(kind),
 97   _dimension(1),
 98   _higher_dimension(nullptr),
 99   _lower_dimension(nullptr) {
100   // Arrays don't add any new methods, so their vtable is the same size as
101   // the vtable of klass Object.
102   set_vtable_length(Universe::base_vtable_size());
103   set_name(name);
104   set_super(Universe::is_bootstrapping() ? nullptr : vmClasses::Object_klass());
105   set_layout_helper(Klass::_lh_neutral_value);
106   set_is_cloneable(); // All arrays are considered to be cloneable (See JLS 20.1.5)
107   JFR_ONLY(INIT_ID(this);)
108   log_array_class_load(this);
109 }
110 
111 
112 // Initialization of vtables and mirror object is done separately from base_create_array_klass,
113 // since a GC can happen. At this point all instance variables of the ArrayKlass must be setup.
114 void ArrayKlass::complete_create_array_klass(ArrayKlass* k, Klass* super_klass, ModuleEntry* module_entry, TRAPS) {
115   k->initialize_supers(super_klass, nullptr, CHECK);
116   k->vtable().initialize_vtable();
117 
118   // During bootstrapping, before java.base is defined, the module_entry may not be present yet.
119   // These classes will be put on a fixup list and their module fields will be patched once
120   // java.base is defined.
121   assert((module_entry != nullptr) || ((module_entry == nullptr) && !ModuleEntryTable::javabase_defined()),
122          "module entry not available post " JAVA_BASE_NAME " definition");
123   oop module = (module_entry != nullptr) ? module_entry->module() : (oop)nullptr;
124   java_lang_Class::create_mirror(k, Handle(THREAD, k->class_loader()), Handle(THREAD, module), Handle(), Handle(), CHECK);
125 }
126 
127 ArrayKlass* ArrayKlass::array_klass(int n, TRAPS) {
128 
129   assert(dimension() <= n, "check order of chain");
130   int dim = dimension();
131   if (dim == n) return this;
132 
133   // lock-free read needs acquire semantics
134   if (higher_dimension_acquire() == nullptr) {
135 
136     // Ensure atomic creation of higher dimensions
137     RecursiveLocker rl(MultiArray_lock, THREAD);
138 
139     if (higher_dimension() == nullptr) {
140       // Create multi-dim klass object and link them together
141       ObjArrayKlass* ak =
142           ObjArrayKlass::allocate_objArray_klass(class_loader_data(), dim + 1, this, CHECK_NULL);
143       // use 'release' to pair with lock-free load
144       release_set_higher_dimension(ak);
145       assert(ak->lower_dimension() == this, "lower dimension mismatch");
146     }
147   }
148 
149   ObjArrayKlass* ak = higher_dimension();
150   assert(ak != nullptr, "should be set");
151   THREAD->check_possible_safepoint();
152   return ak->array_klass(n, THREAD);
153 }
154 
155 ArrayKlass* ArrayKlass::array_klass_or_null(int n) {
156 
157   assert(dimension() <= n, "check order of chain");
158   int dim = dimension();
159   if (dim == n) return this;
160 
161   // lock-free read needs acquire semantics
162   if (higher_dimension_acquire() == nullptr) {
163     return nullptr;
164   }
165 
166   ObjArrayKlass *ak = higher_dimension();
167   return ak->array_klass_or_null(n);
168 }
169 
170 ArrayKlass* ArrayKlass::array_klass(TRAPS) {
171   return array_klass(dimension() +  1, THREAD);
172 }
173 
174 ArrayKlass* ArrayKlass::array_klass_or_null() {
175   return array_klass_or_null(dimension() +  1);
176 }
177 
178 
179 GrowableArray<Klass*>* ArrayKlass::compute_secondary_supers(int num_extra_slots,
180                                                             Array<InstanceKlass*>* transitive_interfaces) {
181   // interfaces = { cloneable_klass, serializable_klass };
182   assert(num_extra_slots == 0, "sanity of primitive array type");
183   assert(transitive_interfaces == nullptr, "sanity");
184   // Must share this for correct bootstrapping!
185   set_secondary_supers(Universe::the_array_interfaces_array(),
186                        Universe::the_array_interfaces_bitmap());
187   return nullptr;
188 }
189 
190 objArrayOop ArrayKlass::allocate_arrayArray(int n, int length, TRAPS) {
191   check_array_allocation_length(length, arrayOopDesc::max_array_length(T_ARRAY), CHECK_NULL);
192   size_t size = objArrayOopDesc::object_size(length);
193   ArrayKlass* ak = array_klass(n + dimension(), CHECK_NULL);
194   objArrayOop o = (objArrayOop)Universe::heap()->array_allocate(ak, size, length,
195                                                                 /* do_zero */ true, CHECK_NULL);
196   // initialization to null not necessary, area already cleared
197   return o;
198 }
199 
200 // JVMTI support
201 
202 jint ArrayKlass::jvmti_class_status() const {
203   return JVMTI_CLASS_STATUS_ARRAY;
204 }
205 
206 void ArrayKlass::metaspace_pointers_do(MetaspaceClosure* it) {
207   Klass::metaspace_pointers_do(it);
208 
209   ResourceMark rm;
210   log_trace(cds)("Iter(ArrayKlass): %p (%s)", this, external_name());
211 
212   // need to cast away volatile
213   it->push((Klass**)&_higher_dimension);
214   it->push((Klass**)&_lower_dimension);
215 }
216 
217 #if INCLUDE_CDS
218 void ArrayKlass::remove_unshareable_info() {
219   Klass::remove_unshareable_info();
220   if (_higher_dimension != nullptr) {
221     ArrayKlass *ak = higher_dimension();
222     ak->remove_unshareable_info();
223   }
224 }
225 
226 void ArrayKlass::remove_java_mirror() {
227   Klass::remove_java_mirror();
228   if (_higher_dimension != nullptr) {
229     ArrayKlass *ak = higher_dimension();
230     ak->remove_java_mirror();
231   }
232 }
233 
234 void ArrayKlass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
235   Klass::restore_unshareable_info(loader_data, protection_domain, CHECK);
236   // Klass recreates the component mirror also
237 
238   if (_higher_dimension != nullptr) {
239     ArrayKlass *ak = higher_dimension();
240     log_array_class_load(ak);
241     ak->restore_unshareable_info(loader_data, protection_domain, CHECK);
242   }
243 }
244 
245 void ArrayKlass::cds_print_value_on(outputStream* st) const {
246   assert(is_klass(), "must be klass");
247   st->print("      - array: %s", internal_name());
248   if (_higher_dimension != nullptr) {
249     ArrayKlass* ak = higher_dimension();
250     st->cr();
251     ak->cds_print_value_on(st);
252   }
253 }
254 #endif // INCLUDE_CDS
255 
256 void ArrayKlass::log_array_class_load(Klass* k) {
257   LogTarget(Debug, class, load, array) lt;
258   if (lt.is_enabled()) {
259     LogStream ls(lt);
260     ResourceMark rm;
261     ls.print("%s", k->name()->as_klass_external_name());
262     if (MetaspaceShared::is_shared_dynamic((void*)k)) {
263       ls.print(" source: shared objects file (top)");
264     } else if (MetaspaceShared::is_shared_static((void*)k)) {
265       ls.print(" source: shared objects file");
266     }
267     ls.cr();
268   }
269 }
270 
271 // Printing
272 
273 void ArrayKlass::print_on(outputStream* st) const {
274   assert(is_klass(), "must be klass");
275   Klass::print_on(st);
276 }
277 
278 void ArrayKlass::print_value_on(outputStream* st) const {
279   assert(is_klass(), "must be klass");
280   for(int index = 0; index < dimension(); index++) {
281     st->print("[]");
282   }
283 }
284 
285 void ArrayKlass::oop_print_on(oop obj, outputStream* st) {
286   assert(obj->is_array(), "must be array");
287   Klass::oop_print_on(obj, st);
288   st->print_cr(" - length: %d", arrayOop(obj)->length());
289 }
290 
291 
292 // Verification
293 
294 void ArrayKlass::verify_on(outputStream* st) {
295   Klass::verify_on(st);
296 }
297 
298 void ArrayKlass::oop_verify_on(oop obj, outputStream* st) {
299   guarantee(obj->is_array(), "must be array");
300   arrayOop a = arrayOop(obj);
301   guarantee(a->length() >= 0, "array with negative length?");
302 }