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/moduleEntry.hpp"
  27 #include "classfile/packageEntry.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "gc/shared/collectedHeap.inline.hpp"
  32 #include "gc/shared/specialized_oop_closures.hpp"
  33 #include "memory/iterator.inline.hpp"
  34 #include "memory/metadataFactory.hpp"
  35 #include "memory/metaspaceClosure.hpp"
  36 #include "memory/resourceArea.hpp"
  37 #include "memory/universe.inline.hpp"
  38 #include "oops/arrayKlass.inline.hpp"
  39 #include "oops/instanceKlass.hpp"
  40 #include "oops/klass.inline.hpp"
  41 #include "oops/objArrayKlass.inline.hpp"
  42 #include "oops/objArrayOop.inline.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "oops/symbol.hpp"
  45 #include "runtime/handles.inline.hpp"
  46 #include "runtime/mutexLocker.hpp"
  47 #include "utilities/copy.hpp"
  48 #include "utilities/macros.hpp"
  49 
  50 ObjArrayKlass* ObjArrayKlass::allocate(ClassLoaderData* loader_data, int n, Klass* k, Symbol* name, TRAPS) {
  51   assert(ObjArrayKlass::header_size() <= InstanceKlass::header_size(),
  52       "array klasses must be same size as InstanceKlass");
  53 
  54   int size = ArrayKlass::static_size(ObjArrayKlass::header_size());
  55 
  56   return new (loader_data, size, THREAD) ObjArrayKlass(n, k, name);
  57 }
  58 
  59 Klass* ObjArrayKlass::allocate_objArray_klass(ClassLoaderData* loader_data,
  60                                                 int n, Klass* element_klass, TRAPS) {
  61 
  62   // Eagerly allocate the direct array supertype.
  63   Klass* super_klass = NULL;
  64   if (!Universe::is_bootstrapping() || SystemDictionary::Object_klass_loaded()) {
  65     Klass* element_super = element_klass->super();
  66     if (element_super != NULL) {
  67       // The element type has a direct super.  E.g., String[] has direct super of Object[].
  68       super_klass = element_super->array_klass_or_null();
  69       bool supers_exist = super_klass != NULL;
  70       // Also, see if the element has secondary supertypes.
  71       // We need an array type for each.
  72       Array<Klass*>* element_supers = element_klass->secondary_supers();
  73       for( int i = element_supers->length()-1; i >= 0; i-- ) {
  74         Klass* elem_super = element_supers->at(i);
  75         if (elem_super->array_klass_or_null() == NULL) {
  76           supers_exist = false;
  77           break;
  78         }
  79       }
  80       if (!supers_exist) {
  81         // Oops.  Not allocated yet.  Back out, allocate it, and retry.
  82         Klass* ek = NULL;
  83         {
  84           MutexUnlocker mu(MultiArray_lock);
  85           MutexUnlocker mc(Compile_lock);   // for vtables
  86           super_klass = element_super->array_klass(CHECK_0);
  87           for( int i = element_supers->length()-1; i >= 0; i-- ) {
  88             Klass* elem_super = element_supers->at(i);
  89             elem_super->array_klass(CHECK_0);
  90           }
  91           // Now retry from the beginning
  92           ek = element_klass->array_klass(n, CHECK_0);
  93         }  // re-lock
  94         return ek;
  95       }
  96     } else {
  97       // The element type is already Object.  Object[] has direct super of Object.
  98       super_klass = SystemDictionary::Object_klass();
  99     }
 100   }
 101 
 102   // Create type name for klass.
 103   Symbol* name = NULL;
 104   if (!element_klass->is_instance_klass() ||
 105       (name = InstanceKlass::cast(element_klass)->array_name()) == NULL) {
 106 
 107     ResourceMark rm(THREAD);
 108     char *name_str = element_klass->name()->as_C_string();
 109     int len = element_klass->name()->utf8_length();
 110     char *new_str = NEW_RESOURCE_ARRAY(char, len + 4);
 111     int idx = 0;
 112     new_str[idx++] = '[';
 113     if (element_klass->is_instance_klass()) { // it could be an array or simple type
 114       new_str[idx++] = 'L';
 115     }
 116     memcpy(&new_str[idx], name_str, len * sizeof(char));
 117     idx += len;
 118     if (element_klass->is_instance_klass()) {
 119       new_str[idx++] = ';';
 120     }
 121     new_str[idx++] = '\0';
 122     name = SymbolTable::new_permanent_symbol(new_str, CHECK_0);
 123     if (element_klass->is_instance_klass()) {
 124       InstanceKlass* ik = InstanceKlass::cast(element_klass);
 125       ik->set_array_name(name);
 126     }
 127   }
 128 
 129   // Initialize instance variables
 130   ObjArrayKlass* oak = ObjArrayKlass::allocate(loader_data, n, element_klass, name, CHECK_0);
 131 
 132   // Add all classes to our internal class loader list here,
 133   // including classes in the bootstrap (NULL) class loader.
 134   // GC walks these as strong roots.
 135   loader_data->add_class(oak);
 136 
 137   ModuleEntry* module = oak->module();
 138   assert(module != NULL, "No module entry for array");
 139 
 140   // Call complete_create_array_klass after all instance variables has been initialized.
 141   ArrayKlass::complete_create_array_klass(oak, super_klass, module, CHECK_0);
 142 
 143   return oak;
 144 }
 145 
 146 ObjArrayKlass::ObjArrayKlass(int n, Klass* element_klass, Symbol* name) : ArrayKlass(name) {
 147   this->set_dimension(n);
 148   this->set_element_klass(element_klass);
 149   // decrement refcount because object arrays are not explicitly freed.  The
 150   // InstanceKlass array_name() keeps the name counted while the klass is
 151   // loaded.
 152   name->decrement_refcount();
 153 
 154   Klass* bk;
 155   if (element_klass->is_objArray_klass()) {
 156     bk = ObjArrayKlass::cast(element_klass)->bottom_klass();
 157   } else {
 158     bk = element_klass;
 159   }
 160   assert(bk != NULL && (bk->is_instance_klass() || bk->is_typeArray_klass()), "invalid bottom klass");
 161   this->set_bottom_klass(bk);
 162   this->set_class_loader_data(bk->class_loader_data());
 163 
 164   this->set_layout_helper(array_layout_helper(T_OBJECT));
 165   assert(this->is_array_klass(), "sanity");
 166   assert(this->is_objArray_klass(), "sanity");
 167 }
 168 
 169 int ObjArrayKlass::oop_size(oop obj) const {
 170   assert(obj->is_objArray(), "must be object array");
 171   return objArrayOop(obj)->object_size();
 172 }
 173 
 174 objArrayOop ObjArrayKlass::allocate(int length, TRAPS) {
 175   if (length >= 0) {
 176     if (length <= arrayOopDesc::max_array_length(T_OBJECT)) {
 177       int size = objArrayOopDesc::object_size(length);
 178       return (objArrayOop)CollectedHeap::array_allocate(this, size, length, THREAD);
 179     } else {
 180       report_java_out_of_memory("Requested array size exceeds VM limit");
 181       JvmtiExport::post_array_size_exhausted();
 182       THROW_OOP_0(Universe::out_of_memory_error_array_size());
 183     }
 184   } else {
 185     THROW_0(vmSymbols::java_lang_NegativeArraySizeException());
 186   }
 187 }
 188 
 189 static int multi_alloc_counter = 0;
 190 
 191 oop ObjArrayKlass::multi_allocate(int rank, jint* sizes, TRAPS) {
 192   int length = *sizes;
 193   // Call to lower_dimension uses this pointer, so most be called before a
 194   // possible GC
 195   Klass* ld_klass = lower_dimension();
 196   // If length < 0 allocate will throw an exception.
 197   objArrayOop array = allocate(length, CHECK_NULL);
 198   objArrayHandle h_array (THREAD, array);
 199   if (rank > 1) {
 200     if (length != 0) {
 201       for (int index = 0; index < length; index++) {
 202         ArrayKlass* ak = ArrayKlass::cast(ld_klass);
 203         oop sub_array = ak->multi_allocate(rank-1, &sizes[1], CHECK_NULL);
 204         h_array->obj_at_put(index, sub_array);
 205       }
 206     } else {
 207       // Since this array dimension has zero length, nothing will be
 208       // allocated, however the lower dimension values must be checked
 209       // for illegal values.
 210       for (int i = 0; i < rank - 1; ++i) {
 211         sizes += 1;
 212         if (*sizes < 0) {
 213           THROW_0(vmSymbols::java_lang_NegativeArraySizeException());
 214         }
 215       }
 216     }
 217   }
 218   return h_array();
 219 }
 220 
 221 // Either oop or narrowOop depending on UseCompressedOops.
 222 template <class T> void ObjArrayKlass::do_copy(arrayOop s, T* src,
 223                                arrayOop d, T* dst, int length, TRAPS) {
 224 
 225   BarrierSet* bs = Universe::heap()->barrier_set();
 226   // For performance reasons, we assume we are that the write barrier we
 227   // are using has optimized modes for arrays of references.  At least one
 228   // of the asserts below will fail if this is not the case.
 229   assert(bs->has_write_ref_array_opt(), "Barrier set must have ref array opt");
 230   assert(bs->has_write_ref_array_pre_opt(), "For pre-barrier as well.");
 231 
 232   if (s == d) {
 233     // since source and destination are equal we do not need conversion checks.
 234     assert(length > 0, "sanity check");
 235     bs->write_ref_array_pre(dst, length);
 236     Copy::conjoint_oops_atomic(src, dst, length);
 237   } else {
 238     // We have to make sure all elements conform to the destination array
 239     Klass* bound = ObjArrayKlass::cast(d->klass())->element_klass();
 240     Klass* stype = ObjArrayKlass::cast(s->klass())->element_klass();
 241     if (stype == bound || stype->is_subtype_of(bound)) {
 242       // elements are guaranteed to be subtypes, so no check necessary
 243       bs->write_ref_array_pre(dst, length);
 244       Copy::conjoint_oops_atomic(src, dst, length);
 245     } else {
 246       // slow case: need individual subtype checks
 247       // note: don't use obj_at_put below because it includes a redundant store check
 248       T* from = src;
 249       T* end = from + length;
 250       for (T* p = dst; from < end; from++, p++) {
 251         // XXX this is going to be slow.
 252         T element = *from;
 253         // even slower now
 254         bool element_is_null = oopDesc::is_null(element);
 255         oop new_val = element_is_null ? oop(NULL)
 256                                       : oopDesc::decode_heap_oop_not_null(element);
 257         if (element_is_null ||
 258             (new_val->klass())->is_subtype_of(bound)) {
 259           bs->write_ref_field_pre(p, new_val);
 260           *p = element;
 261         } else {
 262           // We must do a barrier to cover the partial copy.
 263           const size_t pd = pointer_delta(p, dst, (size_t)heapOopSize);
 264           // pointer delta is scaled to number of elements (length field in
 265           // objArrayOop) which we assume is 32 bit.
 266           assert(pd == (size_t)(int)pd, "length field overflow");
 267           bs->write_ref_array((HeapWord*)dst, pd);
 268           THROW(vmSymbols::java_lang_ArrayStoreException());
 269           return;
 270         }
 271       }
 272     }
 273   }
 274   bs->write_ref_array((HeapWord*)dst, length);
 275 }
 276 
 277 void ObjArrayKlass::copy_array(arrayOop s, int src_pos, arrayOop d,
 278                                int dst_pos, int length, TRAPS) {
 279   assert(s->is_objArray(), "must be obj array");
 280 
 281   if (!d->is_objArray()) {
 282     THROW(vmSymbols::java_lang_ArrayStoreException());
 283   }
 284 
 285   // Check is all offsets and lengths are non negative
 286   if (src_pos < 0 || dst_pos < 0 || length < 0) {
 287     THROW(vmSymbols::java_lang_ArrayIndexOutOfBoundsException());
 288   }
 289   // Check if the ranges are valid
 290   if  ( (((unsigned int) length + (unsigned int) src_pos) > (unsigned int) s->length())
 291      || (((unsigned int) length + (unsigned int) dst_pos) > (unsigned int) d->length()) ) {
 292     THROW(vmSymbols::java_lang_ArrayIndexOutOfBoundsException());
 293   }
 294 
 295   // Special case. Boundary cases must be checked first
 296   // This allows the following call: copy_array(s, s.length(), d.length(), 0).
 297   // This is correct, since the position is supposed to be an 'in between point', i.e., s.length(),
 298   // points to the right of the last element.
 299   if (length==0) {
 300     return;
 301   }
 302   if (UseCompressedOops) {
 303     narrowOop* const src = objArrayOop(s)->obj_at_addr<narrowOop>(src_pos);
 304     narrowOop* const dst = objArrayOop(d)->obj_at_addr<narrowOop>(dst_pos);
 305     do_copy<narrowOop>(s, src, d, dst, length, CHECK);
 306   } else {
 307     oop* const src = objArrayOop(s)->obj_at_addr<oop>(src_pos);
 308     oop* const dst = objArrayOop(d)->obj_at_addr<oop>(dst_pos);
 309     do_copy<oop> (s, src, d, dst, length, CHECK);
 310   }
 311 }
 312 
 313 
 314 Klass* ObjArrayKlass::array_klass_impl(bool or_null, int n, TRAPS) {
 315 
 316   assert(dimension() <= n, "check order of chain");
 317   int dim = dimension();
 318   if (dim == n) return this;
 319 
 320   // lock-free read needs acquire semantics
 321   if (higher_dimension_acquire() == NULL) {
 322     if (or_null)  return NULL;
 323 
 324     ResourceMark rm;
 325     JavaThread *jt = (JavaThread *)THREAD;
 326     {
 327       MutexLocker mc(Compile_lock, THREAD);   // for vtables
 328       // Ensure atomic creation of higher dimensions
 329       MutexLocker mu(MultiArray_lock, THREAD);
 330 
 331       // Check if another thread beat us
 332       if (higher_dimension() == NULL) {
 333 
 334         // Create multi-dim klass object and link them together
 335         Klass* k =
 336           ObjArrayKlass::allocate_objArray_klass(class_loader_data(), dim + 1, this, CHECK_NULL);
 337         ObjArrayKlass* ak = ObjArrayKlass::cast(k);
 338         ak->set_lower_dimension(this);
 339         // use 'release' to pair with lock-free load
 340         release_set_higher_dimension(ak);
 341         assert(ak->is_objArray_klass(), "incorrect initialization of ObjArrayKlass");
 342       }
 343     }
 344   } else {
 345     CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
 346   }
 347 
 348   ObjArrayKlass *ak = ObjArrayKlass::cast(higher_dimension());
 349   if (or_null) {
 350     return ak->array_klass_or_null(n);
 351   }
 352   return ak->array_klass(n, THREAD);
 353 }
 354 
 355 Klass* ObjArrayKlass::array_klass_impl(bool or_null, TRAPS) {
 356   return array_klass_impl(or_null, dimension() +  1, THREAD);
 357 }
 358 
 359 bool ObjArrayKlass::can_be_primary_super_slow() const {
 360   if (!bottom_klass()->can_be_primary_super())
 361     // array of interfaces
 362     return false;
 363   else
 364     return Klass::can_be_primary_super_slow();
 365 }
 366 
 367 GrowableArray<Klass*>* ObjArrayKlass::compute_secondary_supers(int num_extra_slots) {
 368   // interfaces = { cloneable_klass, serializable_klass, elemSuper[], ... };
 369   Array<Klass*>* elem_supers = element_klass()->secondary_supers();
 370   int num_elem_supers = elem_supers == NULL ? 0 : elem_supers->length();
 371   int num_secondaries = num_extra_slots + 2 + num_elem_supers;
 372   if (num_secondaries == 2) {
 373     // Must share this for correct bootstrapping!
 374     set_secondary_supers(Universe::the_array_interfaces_array());
 375     return NULL;
 376   } else {
 377     GrowableArray<Klass*>* secondaries = new GrowableArray<Klass*>(num_elem_supers+2);
 378     secondaries->push(SystemDictionary::Cloneable_klass());
 379     secondaries->push(SystemDictionary::Serializable_klass());
 380     for (int i = 0; i < num_elem_supers; i++) {
 381       Klass* elem_super = (Klass*) elem_supers->at(i);
 382       Klass* array_super = elem_super->array_klass_or_null();
 383       assert(array_super != NULL, "must already have been created");
 384       secondaries->push(array_super);
 385     }
 386     return secondaries;
 387   }
 388 }
 389 
 390 bool ObjArrayKlass::compute_is_subtype_of(Klass* k) {
 391   if (!k->is_objArray_klass())
 392     return ArrayKlass::compute_is_subtype_of(k);
 393 
 394   ObjArrayKlass* oak = ObjArrayKlass::cast(k);
 395   return element_klass()->is_subtype_of(oak->element_klass());
 396 }
 397 
 398 void ObjArrayKlass::initialize(TRAPS) {
 399   bottom_klass()->initialize(THREAD);  // dispatches to either InstanceKlass or TypeArrayKlass
 400 }
 401 
 402 void ObjArrayKlass::metaspace_pointers_do(MetaspaceClosure* it) {
 403   ArrayKlass::metaspace_pointers_do(it);
 404   it->push(&_element_klass);
 405   it->push(&_bottom_klass);
 406 }
 407 
 408 // JVM support
 409 
 410 jint ObjArrayKlass::compute_modifier_flags(TRAPS) const {
 411   // The modifier for an objectArray is the same as its element
 412   if (element_klass() == NULL) {
 413     assert(Universe::is_bootstrapping(), "partial objArray only at startup");
 414     return JVM_ACC_ABSTRACT | JVM_ACC_FINAL | JVM_ACC_PUBLIC;
 415   }
 416   // Return the flags of the bottom element type.
 417   jint element_flags = bottom_klass()->compute_modifier_flags(CHECK_0);
 418 
 419   return (element_flags & (JVM_ACC_PUBLIC | JVM_ACC_PRIVATE | JVM_ACC_PROTECTED))
 420                         | (JVM_ACC_ABSTRACT | JVM_ACC_FINAL);
 421 }
 422 
 423 ModuleEntry* ObjArrayKlass::module() const {
 424   assert(bottom_klass() != NULL, "ObjArrayKlass returned unexpected NULL bottom_klass");
 425   // The array is defined in the module of its bottom class
 426   return bottom_klass()->module();
 427 }
 428 
 429 PackageEntry* ObjArrayKlass::package() const {
 430   assert(bottom_klass() != NULL, "ObjArrayKlass returned unexpected NULL bottom_klass");
 431   return bottom_klass()->package();
 432 }
 433 
 434 // Printing
 435 
 436 void ObjArrayKlass::print_on(outputStream* st) const {
 437 #ifndef PRODUCT
 438   Klass::print_on(st);
 439   st->print(" - instance klass: ");
 440   element_klass()->print_value_on(st);
 441   st->cr();
 442 #endif //PRODUCT
 443 }
 444 
 445 void ObjArrayKlass::print_value_on(outputStream* st) const {
 446   assert(is_klass(), "must be klass");
 447 
 448   element_klass()->print_value_on(st);
 449   st->print("[]");
 450 }
 451 
 452 #ifndef PRODUCT
 453 
 454 void ObjArrayKlass::oop_print_on(oop obj, outputStream* st) {
 455   ArrayKlass::oop_print_on(obj, st);
 456   assert(obj->is_objArray(), "must be objArray");
 457   objArrayOop oa = objArrayOop(obj);
 458   int print_len = MIN2((intx) oa->length(), MaxElementPrintSize);
 459   for(int index = 0; index < print_len; index++) {
 460     st->print(" - %3d : ", index);
 461     oa->obj_at(index)->print_value_on(st);
 462     st->cr();
 463   }
 464   int remaining = oa->length() - print_len;
 465   if (remaining > 0) {
 466     st->print_cr(" - <%d more elements, increase MaxElementPrintSize to print>", remaining);
 467   }
 468 }
 469 
 470 #endif //PRODUCT
 471 
 472 void ObjArrayKlass::oop_print_value_on(oop obj, outputStream* st) {
 473   assert(obj->is_objArray(), "must be objArray");
 474   st->print("a ");
 475   element_klass()->print_value_on(st);
 476   int len = objArrayOop(obj)->length();
 477   st->print("[%d] ", len);
 478   obj->print_address_on(st);
 479 }
 480 
 481 const char* ObjArrayKlass::internal_name() const {
 482   return external_name();
 483 }
 484 
 485 
 486 // Verification
 487 
 488 void ObjArrayKlass::verify_on(outputStream* st) {
 489   ArrayKlass::verify_on(st);
 490   guarantee(element_klass()->is_klass(), "should be klass");
 491   guarantee(bottom_klass()->is_klass(), "should be klass");
 492   Klass* bk = bottom_klass();
 493   guarantee(bk->is_instance_klass() || bk->is_typeArray_klass(),  "invalid bottom klass");
 494 }
 495 
 496 void ObjArrayKlass::oop_verify_on(oop obj, outputStream* st) {
 497   ArrayKlass::oop_verify_on(obj, st);
 498   guarantee(obj->is_objArray(), "must be objArray");
 499   objArrayOop oa = objArrayOop(obj);
 500   for(int index = 0; index < oa->length(); index++) {
 501     guarantee(oa->obj_at(index)->is_oop_or_null(), "should be oop");
 502   }
 503 }