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 "classfile/javaClasses.hpp"
 27 #include "classfile/moduleEntry.hpp"
 28 #include "classfile/vmClasses.hpp"
 29 #include "classfile/vmSymbols.hpp"
 30 #include "gc/shared/collectedHeap.inline.hpp"
 31 #include "jvmtifiles/jvmti.h"
 32 #include "memory/metaspaceClosure.hpp"
 33 #include "memory/resourceArea.hpp"
 34 #include "memory/universe.hpp"
 35 #include "oops/arrayKlass.hpp"
 36 #include "oops/arrayOop.hpp"
 37 #include "oops/instanceKlass.hpp"
 38 #include "oops/klass.inline.hpp"
 39 #include "oops/objArrayOop.hpp"
 40 #include "oops/oop.inline.hpp"
 41 #include "runtime/handles.inline.hpp"
 42 
 43 int ArrayKlass::static_size(int header_size) {
 44   // size of an array klass object
 45   assert(header_size <= InstanceKlass::header_size(), "bad header size");
 46   // If this assert fails, see comments in base_create_array_klass.
 47   header_size = InstanceKlass::header_size();
 48   int vtable_len = Universe::base_vtable_size();
 49   int size = header_size + vtable_len;
 50   return align_metadata_size(size);
 51 }
 52 
 53 
 54 InstanceKlass* ArrayKlass::java_super() const {
 55   if (super() == NULL)  return NULL;  // bootstrap case
 56   // Array klasses have primary supertypes which are not reported to Java.
 57   // Example super chain:  String[][] -> Object[][] -> Object[] -> Object
 58   return vmClasses::Object_klass();
 59 }
 60 
 61 
 62 oop ArrayKlass::multi_allocate(int rank, jint* sizes, TRAPS) {
 63   ShouldNotReachHere();
 64   return NULL;
 65 }
 66 
 67 // find field according to JVM spec 5.4.3.2, returns the klass in which the field is defined
 68 Klass* ArrayKlass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
 69   // There are no fields in an array klass but look to the super class (Object)
 70   assert(super(), "super klass must be present");
 71   return super()->find_field(name, sig, fd);
 72 }
 73 
 74 Method* ArrayKlass::uncached_lookup_method(const Symbol* name,
 75                                            const Symbol* signature,
 76                                            OverpassLookupMode overpass_mode,
 77                                            PrivateLookupMode private_mode) const {
 78   // There are no methods in an array klass but the super class (Object) has some
 79   assert(super(), "super klass must be present");
 80   // Always ignore overpass methods in superclasses, although technically the
 81   // super klass of an array, (j.l.Object) should not have
 82   // any overpass methods present.
 83   return super()->uncached_lookup_method(name, signature, OverpassLookupMode::skip, private_mode);
 84 }
 85 
 86 ArrayKlass::ArrayKlass(Symbol* name, KlassID id) :
 87   Klass(id),
 88   _dimension(1),
 89   _higher_dimension(NULL),
 90   _lower_dimension(NULL) {
 91   // Arrays don't add any new methods, so their vtable is the same size as
 92   // the vtable of klass Object.
 93   set_vtable_length(Universe::base_vtable_size());
 94   set_name(name);
 95   set_super(Universe::is_bootstrapping() ? NULL : vmClasses::Object_klass());
 96   set_layout_helper(Klass::_lh_neutral_value);
 97   set_is_cloneable(); // All arrays are considered to be cloneable (See JLS 20.1.5)
 98   JFR_ONLY(INIT_ID(this);)
 99 }
100 
101 
102 // Initialization of vtables and mirror object is done separatly from base_create_array_klass,
103 // since a GC can happen. At this point all instance variables of the ArrayKlass must be setup.
104 void ArrayKlass::complete_create_array_klass(ArrayKlass* k, Klass* super_klass, ModuleEntry* module_entry, TRAPS) {
105   k->initialize_supers(super_klass, NULL, CHECK);
106   k->vtable().initialize_vtable();
107 
108   // During bootstrapping, before java.base is defined, the module_entry may not be present yet.
109   // These classes will be put on a fixup list and their module fields will be patched once
110   // java.base is defined.
111   assert((module_entry != NULL) || ((module_entry == NULL) && !ModuleEntryTable::javabase_defined()),
112          "module entry not available post " JAVA_BASE_NAME " definition");
113   oop module = (module_entry != NULL) ? module_entry->module() : (oop)NULL;
114   java_lang_Class::create_mirror(k, Handle(THREAD, k->class_loader()), Handle(THREAD, module), Handle(), Handle(), CHECK);
115 }
116 
117 GrowableArray<Klass*>* ArrayKlass::compute_secondary_supers(int num_extra_slots,
118                                                             Array<InstanceKlass*>* transitive_interfaces) {
119   // interfaces = { cloneable_klass, serializable_klass };
120   assert(num_extra_slots == 0, "sanity of primitive array type");
121   assert(transitive_interfaces == NULL, "sanity");
122   // Must share this for correct bootstrapping!
123   set_secondary_supers(Universe::the_array_interfaces_array());
124   return NULL;
125 }
126 
127 objArrayOop ArrayKlass::allocate_arrayArray(int n, int length, TRAPS) {
128   check_array_allocation_length(length, arrayOopDesc::max_array_length(T_ARRAY), CHECK_NULL);
129   int size = objArrayOopDesc::object_size(length);
130   Klass* k = array_klass(n+dimension(), CHECK_NULL);
131   ArrayKlass* ak = ArrayKlass::cast(k);
132   objArrayOop o = (objArrayOop)Universe::heap()->array_allocate(ak, size, length,
133                                                                 /* do_zero */ true, CHECK_NULL);
134   // initialization to NULL not necessary, area already cleared
135   return o;
136 }
137 
138 void ArrayKlass::array_klasses_do(void f(Klass* k, TRAPS), TRAPS) {
139   Klass* k = this;
140   // Iterate over this array klass and all higher dimensions
141   while (k != NULL) {
142     f(k, CHECK);
143     k = ArrayKlass::cast(k)->higher_dimension();
144   }
145 }
146 
147 void ArrayKlass::array_klasses_do(void f(Klass* k)) {
148   Klass* k = this;
149   // Iterate over this array klass and all higher dimensions
150   while (k != NULL) {
151     f(k);
152     k = ArrayKlass::cast(k)->higher_dimension();
153   }
154 }
155 
156 jint ArrayKlass::compute_modifier_flags() const {
157   return JVM_ACC_ABSTRACT | JVM_ACC_FINAL | JVM_ACC_PUBLIC;
158 }
159 
160 // JVMTI support
161 
162 jint ArrayKlass::jvmti_class_status() const {
163   return JVMTI_CLASS_STATUS_ARRAY;
164 }
165 
166 void ArrayKlass::metaspace_pointers_do(MetaspaceClosure* it) {
167   Klass::metaspace_pointers_do(it);
168 
169   ResourceMark rm;
170   log_trace(cds)("Iter(ArrayKlass): %p (%s)", this, external_name());
171 
172   // need to cast away volatile
173   it->push((Klass**)&_higher_dimension);
174   it->push((Klass**)&_lower_dimension);
175 }
176 
177 void ArrayKlass::remove_unshareable_info() {
178   Klass::remove_unshareable_info();
179   if (_higher_dimension != NULL) {
180     ArrayKlass *ak = ArrayKlass::cast(higher_dimension());
181     ak->remove_unshareable_info();
182   }
183 }
184 
185 void ArrayKlass::remove_java_mirror() {
186   Klass::remove_java_mirror();
187   if (_higher_dimension != NULL) {
188     ArrayKlass *ak = ArrayKlass::cast(higher_dimension());
189     ak->remove_java_mirror();
190   }
191 }
192 
193 void ArrayKlass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
194   assert(loader_data == ClassLoaderData::the_null_class_loader_data(), "array classes belong to null loader");
195   Klass::restore_unshareable_info(loader_data, protection_domain, CHECK);
196   // Klass recreates the component mirror also
197 
198   if (_higher_dimension != NULL) {
199     ArrayKlass *ak = ArrayKlass::cast(higher_dimension());
200     ak->restore_unshareable_info(loader_data, protection_domain, CHECK);
201   }
202 }
203 
204 // Printing
205 
206 void ArrayKlass::print_on(outputStream* st) const {
207   assert(is_klass(), "must be klass");
208   Klass::print_on(st);
209 }
210 
211 void ArrayKlass::print_value_on(outputStream* st) const {
212   assert(is_klass(), "must be klass");
213   for(int index = 0; index < dimension(); index++) {
214     st->print("[]");
215   }
216 }
217 
218 void ArrayKlass::oop_print_on(oop obj, outputStream* st) {
219   assert(obj->is_array(), "must be array");
220   Klass::oop_print_on(obj, st);
221   st->print_cr(" - length: %d", arrayOop(obj)->length());
222 }
223 
224 
225 // Verification
226 
227 void ArrayKlass::verify_on(outputStream* st) {
228   Klass::verify_on(st);
229 }
230 
231 void ArrayKlass::oop_verify_on(oop obj, outputStream* st) {
232   guarantee(obj->is_array(), "must be array");
233   arrayOop a = arrayOop(obj);
234   guarantee(a->length() >= 0, "array with negative length?");
235 }