1 /*
   2  * Copyright (c) 1997, 2017, 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/symbolTable.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "gc/shared/collectedHeap.inline.hpp"
  31 #include "gc/shared/gcLocker.hpp"
  32 #include "jvmtifiles/jvmti.h"
  33 #include "memory/metaspaceClosure.hpp"
  34 #include "memory/resourceArea.hpp"
  35 #include "memory/universe.inline.hpp"
  36 #include "oops/arrayKlass.hpp"
  37 #include "oops/objArrayKlass.hpp"
  38 #include "oops/arrayOop.hpp"
  39 #include "oops/instanceKlass.hpp"
  40 #include "oops/objArrayOop.hpp"
  41 #include "oops/oop.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 Klass* 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 SystemDictionary::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) const {
  77   // There are no methods in an array klass but the super class (Object) has some
  78   assert(super(), "super klass must be present");
  79   // Always ignore overpass methods in superclasses, although technically the
  80   // super klass of an array, (j.l.Object) should not have
  81   // any overpass methods present.
  82   return super()->uncached_lookup_method(name, signature, Klass::skip_overpass);
  83 }
  84 
  85 ArrayKlass::ArrayKlass(Symbol* name) :
  86   _dimension(1),
  87   _higher_dimension(NULL),
  88   _lower_dimension(NULL) {
  89     // Arrays don't add any new methods, so their vtable is the same size as
  90     // the vtable of klass Object.
  91     set_vtable_length(Universe::base_vtable_size());
  92     set_name(name);
  93     set_super(Universe::is_bootstrapping() ? (Klass*)NULL : SystemDictionary::Object_klass());
  94     set_layout_helper(Klass::_lh_neutral_value);
  95     set_is_cloneable(); // All arrays are considered to be cloneable (See JLS 20.1.5)
  96     TRACE_INIT_ID(this);
  97 }
  98 
  99 Symbol* ArrayKlass::create_element_klass_array_name(Klass* element_klass, TRAPS) {
 100   Symbol* name = NULL;
 101   if (!element_klass->is_instance_klass() ||
 102       (name = InstanceKlass::cast(element_klass)->array_name()) == NULL) {
 103 
 104     ResourceMark rm(THREAD);
 105     char *name_str = element_klass->name()->as_C_string();
 106     int len = element_klass->name()->utf8_length();
 107     char *new_str = NEW_RESOURCE_ARRAY(char, len + 4);
 108     int idx = 0;
 109     new_str[idx++] = '[';
 110     if (element_klass->is_instance_klass()) { // it could be an array or simple type
 111       // Temporary hack, for arrays of value types, this code should be removed
 112       // once value types have their own array types
 113       new_str[idx++] = 'L';
 114     }
 115     memcpy(&new_str[idx], name_str, len * sizeof(char));
 116     idx += len;
 117     if (element_klass->is_instance_klass()) {
 118       new_str[idx++] = ';';
 119     }
 120     new_str[idx++] = '\0';
 121     name = SymbolTable::new_permanent_symbol(new_str, CHECK_NULL);
 122     if (element_klass->is_instance_klass() || element_klass->is_value()) {
 123       InstanceKlass* ik = InstanceKlass::cast(element_klass);
 124       ik->set_array_name(name);
 125     }
 126   }
 127 
 128   return name;
 129 }
 130 
 131 // Initialization of vtables and mirror object is done separatly from base_create_array_klass,
 132 // since a GC can happen. At this point all instance variables of the ArrayKlass must be setup.
 133 void ArrayKlass::complete_create_array_klass(ArrayKlass* k, Klass* super_klass, ModuleEntry* module_entry, TRAPS) {
 134   ResourceMark rm(THREAD);
 135   k->initialize_supers(super_klass, CHECK);
 136   k->vtable().initialize_vtable(false, CHECK);
 137 
 138   // During bootstrapping, before java.base is defined, the module_entry may not be present yet.
 139   // These classes will be put on a fixup list and their module fields will be patched once
 140   // java.base is defined.
 141   assert((module_entry != NULL) || ((module_entry == NULL) && !ModuleEntryTable::javabase_defined()),
 142          "module entry not available post " JAVA_BASE_NAME " definition");
 143   oop module = (module_entry != NULL) ? module_entry->module() : (oop)NULL;
 144   java_lang_Class::create_mirror(k, Handle(THREAD, k->class_loader()), Handle(THREAD, module), Handle(), CHECK);
 145 }
 146 
 147 GrowableArray<Klass*>* ArrayKlass::compute_secondary_supers(int num_extra_slots) {
 148   // interfaces = { cloneable_klass, serializable_klass };
 149   assert(num_extra_slots == 0, "sanity of primitive array type");
 150   // Must share this for correct bootstrapping!
 151   set_secondary_supers(Universe::the_array_interfaces_array());
 152   return NULL;
 153 }
 154 
 155 bool ArrayKlass::compute_is_subtype_of(Klass* k) {
 156   // An array is a subtype of Serializable, Clonable, and Object
 157   return    k == SystemDictionary::Object_klass()
 158          || k == SystemDictionary::Cloneable_klass()
 159          || k == SystemDictionary::Serializable_klass();
 160 }
 161 
 162 objArrayOop ArrayKlass::allocate_arrayArray(int n, int length, TRAPS) {
 163   if (length < 0) {
 164     THROW_0(vmSymbols::java_lang_NegativeArraySizeException());
 165   }
 166   if (length > arrayOopDesc::max_array_length(T_ARRAY)) {
 167     report_java_out_of_memory("Requested array size exceeds VM limit");
 168     JvmtiExport::post_array_size_exhausted();
 169     THROW_OOP_0(Universe::out_of_memory_error_array_size());
 170   }
 171   int size = objArrayOopDesc::object_size(length);
 172   Klass* k = array_klass(n+dimension(), CHECK_0);
 173   ArrayKlass* ak = ArrayKlass::cast(k);
 174   objArrayOop o =
 175     (objArrayOop)CollectedHeap::array_allocate(ak, size, length, CHECK_0);
 176   // initialization to NULL not necessary, area already cleared
 177   return o;
 178 }
 179 
 180 void ArrayKlass::array_klasses_do(void f(Klass* k, TRAPS), TRAPS) {
 181   Klass* k = this;
 182   // Iterate over this array klass and all higher dimensions
 183   while (k != NULL) {
 184     f(k, CHECK);
 185     k = ArrayKlass::cast(k)->higher_dimension();
 186   }
 187 }
 188 
 189 void ArrayKlass::array_klasses_do(void f(Klass* k)) {
 190   Klass* k = this;
 191   // Iterate over this array klass and all higher dimensions
 192   while (k != NULL) {
 193     f(k);
 194     k = ArrayKlass::cast(k)->higher_dimension();
 195   }
 196 }
 197 
 198 // JVM support
 199 
 200 jint ArrayKlass::compute_modifier_flags(TRAPS) const {
 201   return JVM_ACC_ABSTRACT | JVM_ACC_FINAL | JVM_ACC_PUBLIC;
 202 }
 203 
 204 // JVMTI support
 205 
 206 jint ArrayKlass::jvmti_class_status() const {
 207   return JVMTI_CLASS_STATUS_ARRAY;
 208 }
 209 
 210 void ArrayKlass::metaspace_pointers_do(MetaspaceClosure* it) {
 211   Klass::metaspace_pointers_do(it);
 212 
 213   ResourceMark rm;
 214   log_trace(cds)("Iter(ArrayKlass): %p (%s)", this, external_name());
 215 
 216   // need to cast away volatile
 217   it->push((Klass**)&_higher_dimension);
 218   it->push((Klass**)&_lower_dimension);
 219 }
 220 
 221 void ArrayKlass::remove_unshareable_info() {
 222   Klass::remove_unshareable_info();
 223   if (_higher_dimension != NULL) {
 224     ArrayKlass *ak = ArrayKlass::cast(higher_dimension());
 225     ak->remove_unshareable_info();
 226   }
 227 }
 228 
 229 void ArrayKlass::remove_java_mirror() {
 230   Klass::remove_java_mirror();
 231   if (_higher_dimension != NULL) {
 232     ArrayKlass *ak = ArrayKlass::cast(higher_dimension());
 233     ak->remove_java_mirror();
 234   }
 235 }
 236 
 237 void ArrayKlass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
 238   assert(loader_data == ClassLoaderData::the_null_class_loader_data(), "array classes belong to null loader");
 239   Klass::restore_unshareable_info(loader_data, protection_domain, CHECK);
 240   // Klass recreates the component mirror also
 241 
 242   if (_higher_dimension != NULL) {
 243     ArrayKlass *ak = ArrayKlass::cast(higher_dimension());
 244     ak->restore_unshareable_info(loader_data, protection_domain, CHECK);
 245   }
 246 }
 247 
 248 // Printing
 249 
 250 void ArrayKlass::print_on(outputStream* st) const {
 251   assert(is_klass(), "must be klass");
 252   Klass::print_on(st);
 253 }
 254 
 255 void ArrayKlass::print_value_on(outputStream* st) const {
 256   assert(is_klass(), "must be klass");
 257   for(int index = 0; index < dimension(); index++) {
 258     st->print("[]");
 259   }
 260 }
 261 
 262 void ArrayKlass::oop_print_on(oop obj, outputStream* st) {
 263   assert(obj->is_array(), "must be array");
 264   Klass::oop_print_on(obj, st);
 265   st->print_cr(" - length: %d", arrayOop(obj)->length());
 266 }
 267 
 268 
 269 // Verification
 270 
 271 void ArrayKlass::verify_on(outputStream* st) {
 272   Klass::verify_on(st);
 273 }
 274 
 275 void ArrayKlass::oop_verify_on(oop obj, outputStream* st) {
 276   guarantee(obj->is_array(), "must be array");
 277   arrayOop a = arrayOop(obj);
 278   guarantee(a->length() >= 0, "array with negative length?");
 279 }