1 /*
   2  * Copyright (c) 1997, 2018, 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 "jvm.h"
  27 #include "aot/aotLoader.hpp"
  28 #include "classfile/classFileParser.hpp"
  29 #include "classfile/classFileStream.hpp"
  30 #include "classfile/classLoader.hpp"
  31 #include "classfile/classLoaderData.inline.hpp"
  32 #include "classfile/classLoaderExt.hpp"
  33 #include "classfile/dictionary.hpp"
  34 #include "classfile/javaClasses.inline.hpp"
  35 #include "classfile/klassFactory.hpp"
  36 #include "classfile/loaderConstraints.hpp"
  37 #include "classfile/packageEntry.hpp"
  38 #include "classfile/placeholders.hpp"
  39 #include "classfile/protectionDomainCache.hpp"
  40 #include "classfile/resolutionErrors.hpp"
  41 #include "classfile/stringTable.hpp"
  42 #include "classfile/systemDictionary.hpp"
  43 #include "classfile/vmSymbols.hpp"
  44 #include "code/codeCache.hpp"
  45 #include "compiler/compileBroker.hpp"
  46 #include "gc/shared/gcTraceTime.inline.hpp"
  47 #include "gc/shared/oopStorage.inline.hpp"
  48 #include "interpreter/bytecodeStream.hpp"
  49 #include "interpreter/interpreter.hpp"
  50 #include "logging/log.hpp"
  51 #include "logging/logStream.hpp"
  52 #include "memory/filemap.hpp"
  53 #include "memory/metaspaceClosure.hpp"
  54 #include "memory/oopFactory.hpp"
  55 #include "memory/resourceArea.hpp"
  56 #include "oops/access.inline.hpp"
  57 #include "oops/instanceKlass.hpp"
  58 #include "oops/instanceRefKlass.hpp"
  59 #include "oops/klass.inline.hpp"
  60 #include "oops/method.inline.hpp"
  61 #include "oops/methodData.hpp"
  62 #include "oops/objArrayKlass.hpp"
  63 #include "oops/objArrayOop.inline.hpp"
  64 #include "oops/oop.inline.hpp"
  65 #include "oops/symbol.hpp"
  66 #include "oops/typeArrayKlass.hpp"
  67 #include "prims/jvmtiEnvBase.hpp"
  68 #include "prims/resolvedMethodTable.hpp"
  69 #include "prims/methodHandles.hpp"
  70 #include "runtime/arguments.hpp"
  71 #include "runtime/arguments_ext.hpp"
  72 #include "runtime/biasedLocking.hpp"
  73 #include "runtime/fieldType.hpp"
  74 #include "runtime/handles.inline.hpp"
  75 #include "runtime/java.hpp"
  76 #include "runtime/javaCalls.hpp"
  77 #include "runtime/mutexLocker.hpp"
  78 #include "runtime/orderAccess.inline.hpp"
  79 #include "runtime/sharedRuntime.hpp"
  80 #include "runtime/signature.hpp"
  81 #include "services/classLoadingService.hpp"
  82 #include "services/diagnosticCommand.hpp"
  83 #include "services/threadService.hpp"
  84 #include "trace/tracing.hpp"
  85 #include "utilities/macros.hpp"
  86 #if INCLUDE_CDS
  87 #include "classfile/systemDictionaryShared.hpp"
  88 #endif
  89 #if INCLUDE_JVMCI
  90 #include "jvmci/jvmciRuntime.hpp"
  91 #endif
  92 
  93 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  94 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;
  95 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  96 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  97 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
  98 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
  99 
 100 int         SystemDictionary::_number_of_modifications = 0;
 101 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 102 
 103 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 104                                                           =  { NULL /*, NULL...*/ };
 105 
 106 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 107 
 108 oop         SystemDictionary::_java_system_loader         =  NULL;
 109 oop         SystemDictionary::_java_platform_loader       =  NULL;
 110 
 111 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 112 
 113 // lazily initialized klass variables
 114 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
 115 
 116 // Default ProtectionDomainCacheSize value
 117 
 118 const int defaultProtectionDomainCacheSize = 1009;
 119 
 120 OopStorage* SystemDictionary::_vm_weak_oop_storage = NULL;
 121 
 122 
 123 // ----------------------------------------------------------------------------
 124 // Java-level SystemLoader and PlatformLoader
 125 
 126 oop SystemDictionary::java_system_loader() {
 127   return _java_system_loader;
 128 }
 129 
 130 oop SystemDictionary::java_platform_loader() {
 131   return _java_platform_loader;
 132 }
 133 
 134 void SystemDictionary::compute_java_loaders(TRAPS) {
 135   JavaValue result(T_OBJECT);
 136   InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
 137   JavaCalls::call_static(&result,
 138                          class_loader_klass,
 139                          vmSymbols::getSystemClassLoader_name(),
 140                          vmSymbols::void_classloader_signature(),
 141                          CHECK);
 142 
 143   _java_system_loader = (oop)result.get_jobject();
 144 
 145   JavaCalls::call_static(&result,
 146                          class_loader_klass,
 147                          vmSymbols::getPlatformClassLoader_name(),
 148                          vmSymbols::void_classloader_signature(),
 149                          CHECK);
 150 
 151   _java_platform_loader = (oop)result.get_jobject();
 152 }
 153 
 154 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
 155   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 156   return ClassLoaderDataGraph::find_or_create(class_loader);
 157 }
 158 
 159 // ----------------------------------------------------------------------------
 160 // Parallel class loading check
 161 
 162 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 163   if (class_loader.is_null()) return true;
 164   if (AlwaysLockClassLoader) return false;
 165   return java_lang_ClassLoader::parallelCapable(class_loader());
 166 }
 167 // ----------------------------------------------------------------------------
 168 // ParallelDefineClass flag does not apply to bootclass loader
 169 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 170    if (class_loader.is_null()) return false;
 171    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 172      return true;
 173    }
 174    return false;
 175 }
 176 
 177 // Returns true if the passed class loader is the builtin application class loader
 178 // or a custom system class loader. A customer system class loader can be
 179 // specified via -Djava.system.class.loader.
 180 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 181   if (class_loader == NULL) {
 182     return false;
 183   }
 184   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 185          oopDesc::equals(class_loader, _java_system_loader));
 186 }
 187 
 188 // Returns true if the passed class loader is the platform class loader.
 189 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 190   if (class_loader == NULL) {
 191     return false;
 192   }
 193   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 194 }
 195 
 196 // ----------------------------------------------------------------------------
 197 // Resolving of classes
 198 
 199 // Forwards to resolve_or_null
 200 
 201 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 202   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 203   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 204     // can return a null klass
 205     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 206   }
 207   return klass;
 208 }
 209 
 210 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 211                                                      bool throw_error,
 212                                                      Klass* klass, TRAPS) {
 213   if (HAS_PENDING_EXCEPTION) {
 214     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 215     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 216     // and if so convert it to a NoClassDefFoundError
 217     // And chain the original ClassNotFoundException
 218     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 219       ResourceMark rm(THREAD);
 220       assert(klass == NULL, "Should not have result with exception pending");
 221       Handle e(THREAD, PENDING_EXCEPTION);
 222       CLEAR_PENDING_EXCEPTION;
 223       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 224     } else {
 225       return NULL;
 226     }
 227   }
 228   // Class not found, throw appropriate error or exception depending on value of throw_error
 229   if (klass == NULL) {
 230     ResourceMark rm(THREAD);
 231     if (throw_error) {
 232       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 233     } else {
 234       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 235     }
 236   }
 237   return klass;
 238 }
 239 
 240 
 241 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 242                                            bool throw_error, TRAPS)
 243 {
 244   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 245 }
 246 
 247 
 248 // Forwards to resolve_instance_class_or_null
 249 
 250 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 251   assert(THREAD->can_call_java(),
 252          "can not load classes with compiler thread: class=%s, classloader=%s",
 253          class_name->as_C_string(),
 254          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 255   if (FieldType::is_array(class_name)) {
 256     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 257   } else if (FieldType::is_obj(class_name)) {
 258     ResourceMark rm(THREAD);
 259     // Ignore wrapping L and ;.
 260     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 261                                    class_name->utf8_length() - 2, CHECK_NULL);
 262     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 263   } else {
 264     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 265   }
 266 }
 267 
 268 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 269   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 270 }
 271 
 272 // Forwards to resolve_instance_class_or_null
 273 
 274 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 275                                                      Handle class_loader,
 276                                                      Handle protection_domain,
 277                                                      TRAPS) {
 278   assert(FieldType::is_array(class_name), "must be array");
 279   Klass* k = NULL;
 280   FieldArrayInfo fd;
 281   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 282   // of this call
 283   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 284   if (t == T_OBJECT) {
 285     // naked oop "k" is OK here -- we assign back into it
 286     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 287                                                          class_loader,
 288                                                          protection_domain,
 289                                                          CHECK_NULL);
 290     if (k != NULL) {
 291       k = k->array_klass(fd.dimension(), CHECK_NULL);
 292     }
 293   } else {
 294     k = Universe::typeArrayKlassObj(t);
 295     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 296   }
 297   return k;
 298 }
 299 
 300 
 301 // Must be called for any super-class or super-interface resolution
 302 // during class definition to allow class circularity checking
 303 // super-interface callers:
 304 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 305 // super-class callers:
 306 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 307 //   load_shared_class - while loading a class from shared archive
 308 //   resolve_instance_class_or_null:
 309 //     via: handle_parallel_super_load
 310 //      when resolving a class that has an existing placeholder with
 311 //      a saved superclass [i.e. a defineClass is currently in progress]
 312 //      if another thread is trying to resolve the class, it must do
 313 //      super-class checks on its own thread to catch class circularity
 314 // This last call is critical in class circularity checking for cases
 315 // where classloading is delegated to different threads and the
 316 // classloader lock is released.
 317 // Take the case: Base->Super->Base
 318 //   1. If thread T1 tries to do a defineClass of class Base
 319 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 320 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 321 //    so it tries to load Super
 322 //   3. If we load the class internally, or user classloader uses same thread
 323 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 324 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 325 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 326 //      3.4 calls resolve_super_or_fail Base
 327 //      3.5 finds T1,Base -> throws class circularity
 328 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 329 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 330 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 331 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 332 //      4.4 finds T2, Super -> throws class circularity
 333 // Must be called, even if superclass is null, since this is
 334 // where the placeholder entry is created which claims this
 335 // thread is loading this class/classloader.
 336 // Be careful when modifying this code: once you have run
 337 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 338 // you need to find_and_remove it before returning.
 339 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 340 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 341                                                  Symbol* class_name,
 342                                                  Handle class_loader,
 343                                                  Handle protection_domain,
 344                                                  bool is_superclass,
 345                                                  TRAPS) {
 346 #if INCLUDE_CDS
 347   if (DumpSharedSpaces) {
 348     // Special processing for CDS dump time.
 349     Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 350         class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 351     if (k) {
 352       return k;
 353     }
 354   }
 355 #endif // INCLUDE_CDS
 356 
 357   // Double-check, if child class is already loaded, just return super-class,interface
 358   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 359   // dictionary.
 360   // Make sure there's a placeholder for the *child* before resolving.
 361   // Used as a claim that this thread is currently loading superclass/classloader
 362   // Used here for ClassCircularity checks and also for heap verification
 363   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 364   // Must check ClassCircularity before checking if super class is already loaded.
 365   //
 366   // We might not already have a placeholder if this child_name was
 367   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 368   // the name of the class might not be known until the stream is actually
 369   // parsed.
 370   // Bugs 4643874, 4715493
 371 
 372   ClassLoaderData* loader_data = class_loader_data(class_loader);
 373   Dictionary* dictionary = loader_data->dictionary();
 374   unsigned int d_hash = dictionary->compute_hash(child_name);
 375   unsigned int p_hash = placeholders()->compute_hash(child_name);
 376   int p_index = placeholders()->hash_to_index(p_hash);
 377   // can't throw error holding a lock
 378   bool child_already_loaded = false;
 379   bool throw_circularity_error = false;
 380   {
 381     MutexLocker mu(SystemDictionary_lock, THREAD);
 382     Klass* childk = find_class(d_hash, child_name, dictionary);
 383     Klass* quicksuperk;
 384     // to support // loading: if child done loading, just return superclass
 385     // if class_name, & class_loader don't match:
 386     // if initial define, SD update will give LinkageError
 387     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 388     // so we don't throw an exception here.
 389     // see: nsk redefclass014 & java.lang.instrument Instrument032
 390     if ((childk != NULL ) && (is_superclass) &&
 391        ((quicksuperk = childk->super()) != NULL) &&
 392 
 393          ((quicksuperk->name() == class_name) &&
 394             (oopDesc::equals(quicksuperk->class_loader(), class_loader())))) {
 395            return quicksuperk;
 396     } else {
 397       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 398       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 399           throw_circularity_error = true;
 400       }
 401     }
 402     if (!throw_circularity_error) {
 403       // Be careful not to exit resolve_super
 404       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 405     }
 406   }
 407   if (throw_circularity_error) {
 408       ResourceMark rm(THREAD);
 409       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 410   }
 411 
 412 // java.lang.Object should have been found above
 413   assert(class_name != NULL, "null super class for resolving");
 414   // Resolve the super class or interface, check results on return
 415   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 416                                                     class_loader,
 417                                                     protection_domain,
 418                                                     THREAD);
 419 
 420   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 421   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 422   // or error. GC used to walk the placeholder table as strong roots.
 423   // The instanceKlass is kept alive because the class loader is on the stack,
 424   // which keeps the loader_data alive, as well as all instanceKlasses in
 425   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 426   {
 427     MutexLocker mu(SystemDictionary_lock, THREAD);
 428     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 429     SystemDictionary_lock->notify_all();
 430   }
 431   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 432     // can null superk
 433     superk = handle_resolution_exception(class_name, true, superk, THREAD);
 434   }
 435 
 436   return superk;
 437 }
 438 
 439 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 440                                                   Handle class_loader,
 441                                                   Handle protection_domain,
 442                                                   TRAPS) {
 443   if(!has_checkPackageAccess()) return;
 444 
 445   // Now we have to call back to java to check if the initating class has access
 446   JavaValue result(T_VOID);
 447   LogTarget(Debug, protectiondomain) lt;
 448   if (lt.is_enabled()) {
 449     ResourceMark rm;
 450     // Print out trace information
 451     LogStream ls(lt);
 452     ls.print_cr("Checking package access");
 453     ls.print("class loader: "); class_loader()->print_value_on(&ls);
 454     ls.print(" protection domain: "); protection_domain()->print_value_on(&ls);
 455     ls.print(" loading: "); klass->print_value_on(&ls);
 456     ls.cr();
 457   }
 458 
 459   // This handle and the class_loader handle passed in keeps this class from
 460   // being unloaded through several GC points.
 461   // The class_loader handle passed in is the initiating loader.
 462   Handle mirror(THREAD, klass->java_mirror());
 463 
 464   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 465   JavaCalls::call_special(&result,
 466                          class_loader,
 467                          system_loader,
 468                          vmSymbols::checkPackageAccess_name(),
 469                          vmSymbols::class_protectiondomain_signature(),
 470                          mirror,
 471                          protection_domain,
 472                          THREAD);
 473 
 474   if (HAS_PENDING_EXCEPTION) {
 475     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 476   } else {
 477    log_debug(protectiondomain)("granted");
 478   }
 479 
 480   if (HAS_PENDING_EXCEPTION) return;
 481 
 482   // If no exception has been thrown, we have validated the protection domain
 483   // Insert the protection domain of the initiating class into the set.
 484   {
 485     ClassLoaderData* loader_data = class_loader_data(class_loader);
 486     Dictionary* dictionary = loader_data->dictionary();
 487 
 488     Symbol*  kn = klass->name();
 489     unsigned int d_hash = dictionary->compute_hash(kn);
 490 
 491     MutexLocker mu(SystemDictionary_lock, THREAD);
 492     int d_index = dictionary->hash_to_index(d_hash);
 493     dictionary->add_protection_domain(d_index, d_hash, klass,
 494                                       protection_domain, THREAD);
 495   }
 496 }
 497 
 498 // We only get here if this thread finds that another thread
 499 // has already claimed the placeholder token for the current operation,
 500 // but that other thread either never owned or gave up the
 501 // object lock
 502 // Waits on SystemDictionary_lock to indicate placeholder table updated
 503 // On return, caller must recheck placeholder table state
 504 //
 505 // We only get here if
 506 //  1) custom classLoader, i.e. not bootstrap classloader
 507 //  2) custom classLoader has broken the class loader objectLock
 508 //     so another thread got here in parallel
 509 //
 510 // lockObject must be held.
 511 // Complicated dance due to lock ordering:
 512 // Must first release the classloader object lock to
 513 // allow initial definer to complete the class definition
 514 // and to avoid deadlock
 515 // Reclaim classloader lock object with same original recursion count
 516 // Must release SystemDictionary_lock after notify, since
 517 // class loader lock must be claimed before SystemDictionary_lock
 518 // to prevent deadlocks
 519 //
 520 // The notify allows applications that did an untimed wait() on
 521 // the classloader object lock to not hang.
 522 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 523   assert_lock_strong(SystemDictionary_lock);
 524 
 525   bool calledholdinglock
 526       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 527   assert(calledholdinglock,"must hold lock for notify");
 528   assert((!oopDesc::equals(lockObject(), _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 529   ObjectSynchronizer::notifyall(lockObject, THREAD);
 530   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 531   SystemDictionary_lock->wait();
 532   SystemDictionary_lock->unlock();
 533   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 534   SystemDictionary_lock->lock();
 535 }
 536 
 537 // If the class in is in the placeholder table, class loading is in progress
 538 // For cases where the application changes threads to load classes, it
 539 // is critical to ClassCircularity detection that we try loading
 540 // the superclass on the same thread internally, so we do parallel
 541 // super class loading here.
 542 // This also is critical in cases where the original thread gets stalled
 543 // even in non-circularity situations.
 544 // Note: must call resolve_super_or_fail even if null super -
 545 // to force placeholder entry creation for this class for circularity detection
 546 // Caller must check for pending exception
 547 // Returns non-null Klass* if other thread has completed load
 548 // and we are done,
 549 // If return null Klass* and no pending exception, the caller must load the class
 550 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 551     Symbol* name, Symbol* superclassname, Handle class_loader,
 552     Handle protection_domain, Handle lockObject, TRAPS) {
 553 
 554   ClassLoaderData* loader_data = class_loader_data(class_loader);
 555   Dictionary* dictionary = loader_data->dictionary();
 556   unsigned int d_hash = dictionary->compute_hash(name);
 557   unsigned int p_hash = placeholders()->compute_hash(name);
 558   int p_index = placeholders()->hash_to_index(p_hash);
 559 
 560   // superk is not used, resolve_super called for circularity check only
 561   // This code is reached in two situations. One if this thread
 562   // is loading the same class twice (e.g. ClassCircularity, or
 563   // java.lang.instrument).
 564   // The second is if another thread started the resolve_super first
 565   // and has not yet finished.
 566   // In both cases the original caller will clean up the placeholder
 567   // entry on error.
 568   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 569                                                           superclassname,
 570                                                           class_loader,
 571                                                           protection_domain,
 572                                                           true,
 573                                                           CHECK_NULL);
 574 
 575   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 576   // Serial class loaders and bootstrap classloader do wait for superclass loads
 577  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 578     MutexLocker mu(SystemDictionary_lock, THREAD);
 579     // Check if classloading completed while we were loading superclass or waiting
 580     return find_class(d_hash, name, dictionary);
 581   }
 582 
 583   // must loop to both handle other placeholder updates
 584   // and spurious notifications
 585   bool super_load_in_progress = true;
 586   PlaceholderEntry* placeholder;
 587   while (super_load_in_progress) {
 588     MutexLocker mu(SystemDictionary_lock, THREAD);
 589     // Check if classloading completed while we were loading superclass or waiting
 590     InstanceKlass* check = find_class(d_hash, name, dictionary);
 591     if (check != NULL) {
 592       // Klass is already loaded, so just return it
 593       return check;
 594     } else {
 595       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 596       if (placeholder && placeholder->super_load_in_progress() ){
 597         // We only get here if the application has released the
 598         // classloader lock when another thread was in the middle of loading a
 599         // superclass/superinterface for this class, and now
 600         // this thread is also trying to load this class.
 601         // To minimize surprises, the first thread that started to
 602         // load a class should be the one to complete the loading
 603         // with the classfile it initially expected.
 604         // This logic has the current thread wait once it has done
 605         // all the superclass/superinterface loading it can, until
 606         // the original thread completes the class loading or fails
 607         // If it completes we will use the resulting InstanceKlass
 608         // which we will find below in the systemDictionary.
 609         // We also get here for parallel bootstrap classloader
 610         if (class_loader.is_null()) {
 611           SystemDictionary_lock->wait();
 612         } else {
 613           double_lock_wait(lockObject, THREAD);
 614         }
 615       } else {
 616         // If not in SD and not in PH, other thread's load must have failed
 617         super_load_in_progress = false;
 618       }
 619     }
 620   }
 621   return NULL;
 622 }
 623 
 624 static void post_class_load_event(EventClassLoad* event,
 625                                   const InstanceKlass* k,
 626                                   const ClassLoaderData* init_cld) {
 627 #if INCLUDE_TRACE
 628   assert(event != NULL, "invariant");
 629   assert(k != NULL, "invariant");
 630   if (event->should_commit()) {
 631     event->set_loadedClass(k);
 632     event->set_definingClassLoader(k->class_loader_data());
 633     event->set_initiatingClassLoader(init_cld);
 634     event->commit();
 635   }
 636 #endif // INCLUDE_TRACE
 637 }
 638 
 639 static void class_define_event(InstanceKlass* k,
 640                                const ClassLoaderData* def_cld) {
 641 #if INCLUDE_TRACE
 642   EventClassDefine event;
 643   if (event.should_commit()) {
 644     event.set_definedClass(k);
 645     event.set_definingClassLoader(def_cld);
 646     event.commit();
 647   }
 648 #endif // INCLUDE_TRACE
 649 }
 650 
 651 // Be careful when modifying this code: once you have run
 652 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 653 // you need to find_and_remove it before returning.
 654 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 655 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 656                                                         Handle class_loader,
 657                                                         Handle protection_domain,
 658                                                         TRAPS) {
 659   assert(name != NULL && !FieldType::is_array(name) &&
 660          !FieldType::is_obj(name), "invalid class name");
 661 
 662   EventClassLoad class_load_start_event;
 663 
 664   HandleMark hm(THREAD);
 665 
 666   // Fix for 4474172; see evaluation for more details
 667   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 668   ClassLoaderData* loader_data = register_loader(class_loader);
 669   Dictionary* dictionary = loader_data->dictionary();
 670   unsigned int d_hash = dictionary->compute_hash(name);
 671 
 672   // Do lookup to see if class already exist and the protection domain
 673   // has the right access
 674   // This call uses find which checks protection domain already matches
 675   // All subsequent calls use find_class, and set has_loaded_class so that
 676   // before we return a result we call out to java to check for valid protection domain
 677   // to allow returning the Klass* and add it to the pd_set if it is valid
 678   {
 679     Klass* probe = dictionary->find(d_hash, name, protection_domain);
 680     if (probe != NULL) return probe;
 681   }
 682 
 683   // Non-bootstrap class loaders will call out to class loader and
 684   // define via jvm/jni_DefineClass which will acquire the
 685   // class loader object lock to protect against multiple threads
 686   // defining the class in parallel by accident.
 687   // This lock must be acquired here so the waiter will find
 688   // any successful result in the SystemDictionary and not attempt
 689   // the define.
 690   // ParallelCapable Classloaders and the bootstrap classloader
 691   // do not acquire lock here.
 692   bool DoObjectLock = true;
 693   if (is_parallelCapable(class_loader)) {
 694     DoObjectLock = false;
 695   }
 696 
 697   unsigned int p_hash = placeholders()->compute_hash(name);
 698   int p_index = placeholders()->hash_to_index(p_hash);
 699 
 700   // Class is not in SystemDictionary so we have to do loading.
 701   // Make sure we are synchronized on the class loader before we proceed
 702   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 703   check_loader_lock_contention(lockObject, THREAD);
 704   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 705 
 706   // Check again (after locking) if class already exist in SystemDictionary
 707   bool class_has_been_loaded   = false;
 708   bool super_load_in_progress  = false;
 709   bool havesupername = false;
 710   InstanceKlass* k = NULL;
 711   PlaceholderEntry* placeholder;
 712   Symbol* superclassname = NULL;
 713 
 714   {
 715     MutexLocker mu(SystemDictionary_lock, THREAD);
 716     InstanceKlass* check = find_class(d_hash, name, dictionary);
 717     if (check != NULL) {
 718       // Klass is already loaded, so just return it
 719       class_has_been_loaded = true;
 720       k = check;
 721     } else {
 722       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 723       if (placeholder && placeholder->super_load_in_progress()) {
 724          super_load_in_progress = true;
 725          if (placeholder->havesupername() == true) {
 726            superclassname = placeholder->supername();
 727            havesupername = true;
 728          }
 729       }
 730     }
 731   }
 732 
 733   // If the class is in the placeholder table, class loading is in progress
 734   if (super_load_in_progress && havesupername==true) {
 735     k = handle_parallel_super_load(name,
 736                                    superclassname,
 737                                    class_loader,
 738                                    protection_domain,
 739                                    lockObject, THREAD);
 740     if (HAS_PENDING_EXCEPTION) {
 741       return NULL;
 742     }
 743     if (k != NULL) {
 744       class_has_been_loaded = true;
 745     }
 746   }
 747 
 748   bool throw_circularity_error = false;
 749   if (!class_has_been_loaded) {
 750     bool load_instance_added = false;
 751 
 752     // add placeholder entry to record loading instance class
 753     // Five cases:
 754     // All cases need to prevent modifying bootclasssearchpath
 755     // in parallel with a classload of same classname
 756     // Redefineclasses uses existence of the placeholder for the duration
 757     // of the class load to prevent concurrent redefinition of not completely
 758     // defined classes.
 759     // case 1. traditional classloaders that rely on the classloader object lock
 760     //   - no other need for LOAD_INSTANCE
 761     // case 2. traditional classloaders that break the classloader object lock
 762     //    as a deadlock workaround. Detection of this case requires that
 763     //    this check is done while holding the classloader object lock,
 764     //    and that lock is still held when calling classloader's loadClass.
 765     //    For these classloaders, we ensure that the first requestor
 766     //    completes the load and other requestors wait for completion.
 767     // case 3. Bootstrap classloader - don't own objectLocker
 768     //    This classloader supports parallelism at the classloader level,
 769     //    but only allows a single load of a class/classloader pair.
 770     //    No performance benefit and no deadlock issues.
 771     // case 4. parallelCapable user level classloaders - without objectLocker
 772     //    Allow parallel classloading of a class/classloader pair
 773 
 774     {
 775       MutexLocker mu(SystemDictionary_lock, THREAD);
 776       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 777         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 778         if (oldprobe) {
 779           // only need check_seen_thread once, not on each loop
 780           // 6341374 java/lang/Instrument with -Xcomp
 781           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 782             throw_circularity_error = true;
 783           } else {
 784             // case 1: traditional: should never see load_in_progress.
 785             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 786 
 787               // case 3: bootstrap classloader: prevent futile classloading,
 788               // wait on first requestor
 789               if (class_loader.is_null()) {
 790                 SystemDictionary_lock->wait();
 791               } else {
 792               // case 2: traditional with broken classloader lock. wait on first
 793               // requestor.
 794                 double_lock_wait(lockObject, THREAD);
 795               }
 796               // Check if classloading completed while we were waiting
 797               InstanceKlass* check = find_class(d_hash, name, dictionary);
 798               if (check != NULL) {
 799                 // Klass is already loaded, so just return it
 800                 k = check;
 801                 class_has_been_loaded = true;
 802               }
 803               // check if other thread failed to load and cleaned up
 804               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 805             }
 806           }
 807         }
 808       }
 809       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 810       // case 4: parallelCapable: allow competing threads to try
 811       // LOAD_INSTANCE in parallel
 812 
 813       if (!throw_circularity_error && !class_has_been_loaded) {
 814         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 815         load_instance_added = true;
 816         // For class loaders that do not acquire the classloader object lock,
 817         // if they did not catch another thread holding LOAD_INSTANCE,
 818         // need a check analogous to the acquire ObjectLocker/find_class
 819         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 820         // one final check if the load has already completed
 821         // class loaders holding the ObjectLock shouldn't find the class here
 822         InstanceKlass* check = find_class(d_hash, name, dictionary);
 823         if (check != NULL) {
 824         // Klass is already loaded, so return it after checking/adding protection domain
 825           k = check;
 826           class_has_been_loaded = true;
 827         }
 828       }
 829     }
 830 
 831     // must throw error outside of owning lock
 832     if (throw_circularity_error) {
 833       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 834       ResourceMark rm(THREAD);
 835       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 836     }
 837 
 838     if (!class_has_been_loaded) {
 839 
 840       // Do actual loading
 841       k = load_instance_class(name, class_loader, THREAD);
 842 
 843       // If everything was OK (no exceptions, no null return value), and
 844       // class_loader is NOT the defining loader, do a little more bookkeeping.
 845       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 846         !oopDesc::equals(k->class_loader(), class_loader())) {
 847 
 848         check_constraints(d_hash, k, class_loader, false, THREAD);
 849 
 850         // Need to check for a PENDING_EXCEPTION again; check_constraints
 851         // can throw and doesn't use the CHECK macro.
 852         if (!HAS_PENDING_EXCEPTION) {
 853           { // Grabbing the Compile_lock prevents systemDictionary updates
 854             // during compilations.
 855             MutexLocker mu(Compile_lock, THREAD);
 856             update_dictionary(d_hash, p_index, p_hash,
 857               k, class_loader, THREAD);
 858           }
 859 
 860           if (JvmtiExport::should_post_class_load()) {
 861             Thread *thread = THREAD;
 862             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 863             JvmtiExport::post_class_load((JavaThread *) thread, k);
 864           }
 865         }
 866       }
 867     } // load_instance_class
 868 
 869     if (load_instance_added == true) {
 870       // clean up placeholder entries for LOAD_INSTANCE success or error
 871       // This brackets the SystemDictionary updates for both defining
 872       // and initiating loaders
 873       MutexLocker mu(SystemDictionary_lock, THREAD);
 874       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 875       SystemDictionary_lock->notify_all();
 876     }
 877   }
 878 
 879   if (HAS_PENDING_EXCEPTION || k == NULL) {
 880     return NULL;
 881   }
 882 
 883   post_class_load_event(&class_load_start_event, k, loader_data);
 884 
 885 #ifdef ASSERT
 886   {
 887     ClassLoaderData* loader_data = k->class_loader_data();
 888     MutexLocker mu(SystemDictionary_lock, THREAD);
 889     Klass* kk = find_class(name, loader_data);
 890     assert(kk == k, "should be present in dictionary");
 891   }
 892 #endif
 893 
 894   // return if the protection domain in NULL
 895   if (protection_domain() == NULL) return k;
 896 
 897   // Check the protection domain has the right access
 898   if (dictionary->is_valid_protection_domain(d_hash, name,
 899                                              protection_domain)) {
 900     return k;
 901   }
 902 
 903   // Verify protection domain. If it fails an exception is thrown
 904   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 905 
 906   return k;
 907 }
 908 
 909 
 910 // This routine does not lock the system dictionary.
 911 //
 912 // Since readers don't hold a lock, we must make sure that system
 913 // dictionary entries are only removed at a safepoint (when only one
 914 // thread is running), and are added to in a safe way (all links must
 915 // be updated in an MT-safe manner).
 916 //
 917 // Callers should be aware that an entry could be added just after
 918 // _dictionary->bucket(index) is read here, so the caller will not see
 919 // the new entry.
 920 
 921 Klass* SystemDictionary::find(Symbol* class_name,
 922                               Handle class_loader,
 923                               Handle protection_domain,
 924                               TRAPS) {
 925 
 926   // The result of this call should be consistent with the result
 927   // of the call to resolve_instance_class_or_null().
 928   // See evaluation 6790209 and 4474172 for more details.
 929   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 930   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 931 
 932   if (loader_data == NULL) {
 933     // If the ClassLoaderData has not been setup,
 934     // then the class loader has no entries in the dictionary.
 935     return NULL;
 936   }
 937 
 938   Dictionary* dictionary = loader_data->dictionary();
 939   unsigned int d_hash = dictionary->compute_hash(class_name);
 940   return dictionary->find(d_hash, class_name,
 941                           protection_domain);
 942 }
 943 
 944 
 945 // Look for a loaded instance or array klass by name.  Do not do any loading.
 946 // return NULL in case of error.
 947 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 948                                                       Handle class_loader,
 949                                                       Handle protection_domain,
 950                                                       TRAPS) {
 951   Klass* k = NULL;
 952   assert(class_name != NULL, "class name must be non NULL");
 953 
 954   if (FieldType::is_array(class_name)) {
 955     // The name refers to an array.  Parse the name.
 956     // dimension and object_key in FieldArrayInfo are assigned as a
 957     // side-effect of this call
 958     FieldArrayInfo fd;
 959     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 960     if (t != T_OBJECT) {
 961       k = Universe::typeArrayKlassObj(t);
 962     } else {
 963       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 964     }
 965     if (k != NULL) {
 966       k = k->array_klass_or_null(fd.dimension());
 967     }
 968   } else {
 969     k = find(class_name, class_loader, protection_domain, THREAD);
 970   }
 971   return k;
 972 }
 973 
 974 // Note: this method is much like resolve_from_stream, but
 975 // does not publish the classes via the SystemDictionary.
 976 // Handles unsafe_DefineAnonymousClass and redefineclasses
 977 // RedefinedClasses do not add to the class hierarchy
 978 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
 979                                               Handle class_loader,
 980                                               Handle protection_domain,
 981                                               ClassFileStream* st,
 982                                               const InstanceKlass* host_klass,
 983                                               GrowableArray<Handle>* cp_patches,
 984                                               TRAPS) {
 985 
 986   EventClassLoad class_load_start_event;
 987 
 988   ClassLoaderData* loader_data;
 989   if (host_klass != NULL) {
 990     // Create a new CLD for anonymous class, that uses the same class loader
 991     // as the host_klass
 992     guarantee(oopDesc::equals(host_klass->class_loader(), class_loader()), "should be the same");
 993     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader);
 994   } else {
 995     loader_data = ClassLoaderData::class_loader_data(class_loader());
 996   }
 997 
 998   assert(st != NULL, "invariant");
 999   assert(st->need_verify(), "invariant");
1000 
1001   // Parse stream and create a klass.
1002   // Note that we do this even though this klass might
1003   // already be present in the SystemDictionary, otherwise we would not
1004   // throw potential ClassFormatErrors.
1005 
1006   InstanceKlass* k = KlassFactory::create_from_stream(st,
1007                                                       class_name,
1008                                                       loader_data,
1009                                                       protection_domain,
1010                                                       host_klass,
1011                                                       cp_patches,
1012                                                       CHECK_NULL);
1013 
1014   if (host_klass != NULL && k != NULL) {
1015     // Anonymous classes must update ClassLoaderData holder (was host_klass loader)
1016     // so that they can be unloaded when the mirror is no longer referenced.
1017     k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
1018 
1019     {
1020       MutexLocker mu_r(Compile_lock, THREAD);
1021 
1022       // Add to class hierarchy, initialize vtables, and do possible
1023       // deoptimizations.
1024       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1025 
1026       // But, do not add to dictionary.
1027 
1028       // compiled code dependencies need to be validated anyway
1029       notice_modification();
1030     }
1031 
1032     // Rewrite and patch constant pool here.
1033     k->link_class(CHECK_NULL);
1034     if (cp_patches != NULL) {
1035       k->constants()->patch_resolved_references(cp_patches);
1036     }
1037 
1038     // If it's anonymous, initialize it now, since nobody else will.
1039     k->eager_initialize(CHECK_NULL);
1040 
1041     // notify jvmti
1042     if (JvmtiExport::should_post_class_load()) {
1043         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1044         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1045     }
1046 
1047     post_class_load_event(&class_load_start_event, k, loader_data);
1048   }
1049   assert(host_klass != NULL || NULL == cp_patches,
1050          "cp_patches only found with host_klass");
1051 
1052   return k;
1053 }
1054 
1055 // Add a klass to the system from a stream (called by jni_DefineClass and
1056 // JVM_DefineClass).
1057 // Note: class_name can be NULL. In that case we do not know the name of
1058 // the class until we have parsed the stream.
1059 
1060 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1061                                                      Handle class_loader,
1062                                                      Handle protection_domain,
1063                                                      ClassFileStream* st,
1064                                                      TRAPS) {
1065 
1066   HandleMark hm(THREAD);
1067 
1068   // Classloaders that support parallelism, e.g. bootstrap classloader,
1069   // do not acquire lock here
1070   bool DoObjectLock = true;
1071   if (is_parallelCapable(class_loader)) {
1072     DoObjectLock = false;
1073   }
1074 
1075   ClassLoaderData* loader_data = register_loader(class_loader);
1076 
1077   // Make sure we are synchronized on the class loader before we proceed
1078   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1079   check_loader_lock_contention(lockObject, THREAD);
1080   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1081 
1082   assert(st != NULL, "invariant");
1083 
1084   // Parse the stream and create a klass.
1085   // Note that we do this even though this klass might
1086   // already be present in the SystemDictionary, otherwise we would not
1087   // throw potential ClassFormatErrors.
1088  InstanceKlass* k = NULL;
1089 
1090 #if INCLUDE_CDS
1091   if (!DumpSharedSpaces) {
1092     k = SystemDictionaryShared::lookup_from_stream(class_name,
1093                                                    class_loader,
1094                                                    protection_domain,
1095                                                    st,
1096                                                    CHECK_NULL);
1097   }
1098 #endif
1099 
1100   if (k == NULL) {
1101     if (st->buffer() == NULL) {
1102       return NULL;
1103     }
1104     k = KlassFactory::create_from_stream(st,
1105                                          class_name,
1106                                          loader_data,
1107                                          protection_domain,
1108                                          NULL, // host_klass
1109                                          NULL, // cp_patches
1110                                          CHECK_NULL);
1111   }
1112 
1113   assert(k != NULL, "no klass created");
1114   Symbol* h_name = k->name();
1115   assert(class_name == NULL || class_name == h_name, "name mismatch");
1116 
1117   // Add class just loaded
1118   // If a class loader supports parallel classloading handle parallel define requests
1119   // find_or_define_instance_class may return a different InstanceKlass
1120   if (is_parallelCapable(class_loader)) {
1121     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1122     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1123       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1124       assert(defined_k != NULL, "Should have a klass if there's no exception");
1125       loader_data->add_to_deallocate_list(k);
1126       k = defined_k;
1127     }
1128   } else {
1129     define_instance_class(k, THREAD);
1130   }
1131 
1132   // If defining the class throws an exception register 'k' for cleanup.
1133   if (HAS_PENDING_EXCEPTION) {
1134     assert(k != NULL, "Must have an instance klass here!");
1135     loader_data->add_to_deallocate_list(k);
1136     return NULL;
1137   }
1138 
1139   // Make sure we have an entry in the SystemDictionary on success
1140   debug_only( {
1141     MutexLocker mu(SystemDictionary_lock, THREAD);
1142 
1143     Klass* check = find_class(h_name, k->class_loader_data());
1144     assert(check == k, "should be present in the dictionary");
1145   } );
1146 
1147   return k;
1148 }
1149 
1150 #if INCLUDE_CDS
1151 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1152                                              int number_of_entries) {
1153   assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>),
1154          "bad shared dictionary size.");
1155   _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(),
1156                                       _shared_dictionary_size, t, number_of_entries);
1157 }
1158 
1159 
1160 // If there is a shared dictionary, then find the entry for the
1161 // given shared system class, if any.
1162 
1163 InstanceKlass* SystemDictionary::find_shared_class(Symbol* class_name) {
1164   if (shared_dictionary() != NULL) {
1165     unsigned int d_hash = shared_dictionary()->compute_hash(class_name);
1166     int d_index = shared_dictionary()->hash_to_index(d_hash);
1167 
1168     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1169   } else {
1170     return NULL;
1171   }
1172 }
1173 
1174 
1175 // Load a class from the shared spaces (found through the shared system
1176 // dictionary).  Force the superclass and all interfaces to be loaded.
1177 // Update the class definition to include sibling classes and no
1178 // subclasses (yet).  [Classes in the shared space are not part of the
1179 // object hierarchy until loaded.]
1180 
1181 InstanceKlass* SystemDictionary::load_shared_class(
1182                  Symbol* class_name, Handle class_loader, TRAPS) {
1183   InstanceKlass* ik = find_shared_class(class_name);
1184   // Make sure we only return the boot class for the NULL classloader.
1185   if (ik != NULL &&
1186       ik->is_shared_boot_class() && class_loader.is_null()) {
1187     Handle protection_domain;
1188     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1189   }
1190   return NULL;
1191 }
1192 
1193 // Check if a shared class can be loaded by the specific classloader:
1194 //
1195 // NULL classloader:
1196 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1197 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1198 //     be defined in an unnamed module.
1199 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1200                                                InstanceKlass* ik,
1201                                                Handle class_loader, TRAPS) {
1202   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1203          "Cannot use sharing if java.base is patched");
1204   ResourceMark rm;
1205   int path_index = ik->shared_classpath_index();
1206   ClassLoaderData* loader_data = class_loader_data(class_loader);
1207   if (path_index < 0) {
1208     // path_index < 0 indicates that the class is intended for a custom loader
1209     // and should not be loaded by boot/platform/app loaders
1210     if (loader_data->is_builtin_class_loader_data()) {
1211       return false;
1212     } else {
1213       return true;
1214     }
1215   }
1216   SharedClassPathEntry* ent =
1217             (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1218   if (!Universe::is_module_initialized()) {
1219     assert(ent != NULL && ent->is_modules_image(),
1220            "Loading non-bootstrap classes before the module system is initialized");
1221     assert(class_loader.is_null(), "sanity");
1222     return true;
1223   }
1224   // Get the pkg_entry from the classloader
1225   TempNewSymbol pkg_name = NULL;
1226   PackageEntry* pkg_entry = NULL;
1227   ModuleEntry* mod_entry = NULL;
1228   const char* pkg_string = NULL;
1229   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1230   if (pkg_name != NULL) {
1231     pkg_string = pkg_name->as_C_string();
1232     if (loader_data != NULL) {
1233       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1234     }
1235     if (pkg_entry != NULL) {
1236       mod_entry = pkg_entry->module();
1237     }
1238   }
1239 
1240   // If the archived class is from a module that has been patched at runtime,
1241   // the class cannot be loaded from the archive.
1242   if (mod_entry != NULL && mod_entry->is_patched()) {
1243     return false;
1244   }
1245 
1246   if (class_loader.is_null()) {
1247     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1248     // The NULL classloader can load archived class originated from the
1249     // "modules" jimage and the -Xbootclasspath/a. For class from the
1250     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1251     // by the NULL classloader.
1252     if (mod_entry != NULL) {
1253       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1254       // ModuleEntry's location agrees with the archived class' origination.
1255       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1256         return true; // Module class from the "module" jimage
1257       }
1258     }
1259 
1260     // If the archived class is not from the "module" jimage, the class can be
1261     // loaded by the NULL classloader if
1262     //
1263     // 1. the class is from the unamed package
1264     // 2. or, the class is not from a module defined in the NULL classloader
1265     // 3. or, the class is from an unamed module
1266     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1267       // the class is from the -Xbootclasspath/a
1268       if (pkg_string == NULL ||
1269           pkg_entry == NULL ||
1270           pkg_entry->in_unnamed_module()) {
1271         assert(mod_entry == NULL ||
1272                mod_entry == loader_data->unnamed_module(),
1273                "the unnamed module is not defined in the classloader");
1274         return true;
1275       }
1276     }
1277     return false;
1278   } else {
1279     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1280               ik, class_loader, pkg_string, pkg_name,
1281               pkg_entry, mod_entry, CHECK_(false));
1282     return res;
1283   }
1284 }
1285 
1286 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1287                                                    Handle class_loader,
1288                                                    Handle protection_domain, TRAPS) {
1289 
1290   if (ik != NULL) {
1291     Symbol* class_name = ik->name();
1292 
1293     bool visible = is_shared_class_visible(
1294                             class_name, ik, class_loader, CHECK_NULL);
1295     if (!visible) {
1296       return NULL;
1297     }
1298 
1299     // Resolve the superclass and interfaces. They must be the same
1300     // as in dump time, because the layout of <ik> depends on
1301     // the specific layout of ik->super() and ik->local_interfaces().
1302     //
1303     // If unexpected superclass or interfaces are found, we cannot
1304     // load <ik> from the shared archive.
1305 
1306     if (ik->super() != NULL) {
1307       Symbol*  cn = ik->super()->name();
1308       Klass *s = resolve_super_or_fail(class_name, cn,
1309                                        class_loader, protection_domain, true, CHECK_NULL);
1310       if (s != ik->super()) {
1311         // The dynamically resolved super class is not the same as the one we used during dump time,
1312         // so we cannot use ik.
1313         return NULL;
1314       } else {
1315         assert(s->is_shared(), "must be");
1316       }
1317     }
1318 
1319     Array<Klass*>* interfaces = ik->local_interfaces();
1320     int num_interfaces = interfaces->length();
1321     for (int index = 0; index < num_interfaces; index++) {
1322       Klass* k = interfaces->at(index);
1323       Symbol*  name  = k->name();
1324       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1325       if (k != i) {
1326         // The dynamically resolved interface class is not the same as the one we used during dump time,
1327         // so we cannot use ik.
1328         return NULL;
1329       } else {
1330         assert(i->is_shared(), "must be");
1331       }
1332     }
1333 
1334     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1335         ik, class_name, class_loader, protection_domain, CHECK_NULL);
1336     if (new_ik != NULL) {
1337       // The class is changed by CFLH. Return the new class. The shared class is
1338       // not used.
1339       return new_ik;
1340     }
1341 
1342     // Adjust methods to recover missing data.  They need addresses for
1343     // interpreter entry points and their default native method address
1344     // must be reset.
1345 
1346     // Updating methods must be done under a lock so multiple
1347     // threads don't update these in parallel
1348     //
1349     // Shared classes are all currently loaded by either the bootstrap or
1350     // internal parallel class loaders, so this will never cause a deadlock
1351     // on a custom class loader lock.
1352 
1353     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1354     {
1355       HandleMark hm(THREAD);
1356       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1357       check_loader_lock_contention(lockObject, THREAD);
1358       ObjectLocker ol(lockObject, THREAD, true);
1359       // prohibited package check assumes all classes loaded from archive call
1360       // restore_unshareable_info which calls ik->set_package()
1361       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1362     }
1363 
1364     ik->print_class_load_logging(loader_data, NULL, NULL);
1365 
1366     // For boot loader, ensure that GetSystemPackage knows that a class in this
1367     // package was loaded.
1368     if (class_loader.is_null()) {
1369       int path_index = ik->shared_classpath_index();
1370       ResourceMark rm;
1371       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1372     }
1373 
1374     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1375       // Only dump the classes that can be stored into CDS archive
1376       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1377         ResourceMark rm(THREAD);
1378         classlist_file->print_cr("%s", ik->name()->as_C_string());
1379         classlist_file->flush();
1380       }
1381     }
1382 
1383     // notify a class loaded from shared object
1384     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1385   }
1386 
1387   ik->set_has_passed_fingerprint_check(false);
1388   if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1389     uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1390     uint64_t cds_fp = ik->get_stored_fingerprint();
1391     if (aot_fp != 0 && aot_fp == cds_fp) {
1392       // This class matches with a class saved in an AOT library
1393       ik->set_has_passed_fingerprint_check(true);
1394     } else {
1395       ResourceMark rm;
1396       log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1397     }
1398   }
1399   return ik;
1400 }
1401 
1402 void SystemDictionary::clear_invoke_method_table() {
1403   SymbolPropertyEntry* spe = NULL;
1404   for (int index = 0; index < _invoke_method_table->table_size(); index++) {
1405     SymbolPropertyEntry* p = _invoke_method_table->bucket(index);
1406     while (p != NULL) {
1407       spe = p;
1408       p = p->next();
1409       _invoke_method_table->free_entry(spe);
1410     }
1411   }
1412 }
1413 #endif // INCLUDE_CDS
1414 
1415 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1416 
1417   if (class_loader.is_null()) {
1418     ResourceMark rm;
1419     PackageEntry* pkg_entry = NULL;
1420     bool search_only_bootloader_append = false;
1421     ClassLoaderData *loader_data = class_loader_data(class_loader);
1422 
1423     // Find the package in the boot loader's package entry table.
1424     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1425     if (pkg_name != NULL) {
1426       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1427     }
1428 
1429     // Prior to attempting to load the class, enforce the boot loader's
1430     // visibility boundaries.
1431     if (!Universe::is_module_initialized()) {
1432       // During bootstrapping, prior to module initialization, any
1433       // class attempting to be loaded must be checked against the
1434       // java.base packages in the boot loader's PackageEntryTable.
1435       // No class outside of java.base is allowed to be loaded during
1436       // this bootstrapping window.
1437       if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1438         // Class is either in the unnamed package or in
1439         // a named package within the unnamed module.  Either
1440         // case is outside of java.base, do not attempt to
1441         // load the class post java.base definition.  If
1442         // java.base has not been defined, let the class load
1443         // and its package will be checked later by
1444         // ModuleEntryTable::verify_javabase_packages.
1445         if (ModuleEntryTable::javabase_defined()) {
1446           return NULL;
1447         }
1448       } else {
1449         // Check that the class' package is defined within java.base.
1450         ModuleEntry* mod_entry = pkg_entry->module();
1451         Symbol* mod_entry_name = mod_entry->name();
1452         if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1453           return NULL;
1454         }
1455       }
1456     } else {
1457       // After the module system has been initialized, check if the class'
1458       // package is in a module defined to the boot loader.
1459       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1460         // Class is either in the unnamed package, in a named package
1461         // within a module not defined to the boot loader or in a
1462         // a named package within the unnamed module.  In all cases,
1463         // limit visibility to search for the class only in the boot
1464         // loader's append path.
1465         search_only_bootloader_append = true;
1466       }
1467     }
1468 
1469     // Prior to bootstrapping's module initialization, never load a class outside
1470     // of the boot loader's module path
1471     assert(Universe::is_module_initialized() ||
1472            !search_only_bootloader_append,
1473            "Attempt to load a class outside of boot loader's module path");
1474 
1475     // Search the shared system dictionary for classes preloaded into the
1476     // shared spaces.
1477     InstanceKlass* k = NULL;
1478     {
1479 #if INCLUDE_CDS
1480       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1481       k = load_shared_class(class_name, class_loader, THREAD);
1482 #endif
1483     }
1484 
1485     if (k == NULL) {
1486       // Use VM class loader
1487       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1488       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1489     }
1490 
1491     // find_or_define_instance_class may return a different InstanceKlass
1492     if (k != NULL) {
1493       InstanceKlass* defined_k =
1494         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1495       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1496         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1497         assert(defined_k != NULL, "Should have a klass if there's no exception");
1498         loader_data->add_to_deallocate_list(k);
1499         k = defined_k;
1500       } else if (HAS_PENDING_EXCEPTION) {
1501         loader_data->add_to_deallocate_list(k);
1502         return NULL;
1503       }
1504     }
1505     return k;
1506   } else {
1507     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1508     ResourceMark rm(THREAD);
1509 
1510     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1511     JavaThread* jt = (JavaThread*) THREAD;
1512 
1513     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1514                                ClassLoader::perf_app_classload_selftime(),
1515                                ClassLoader::perf_app_classload_count(),
1516                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1517                                jt->get_thread_stat()->perf_timers_addr(),
1518                                PerfClassTraceTime::CLASS_LOAD);
1519 
1520     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1521     // Translate to external class name format, i.e., convert '/' chars to '.'
1522     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1523 
1524     JavaValue result(T_OBJECT);
1525 
1526     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1527 
1528     // Call public unsynchronized loadClass(String) directly for all class loaders.
1529     // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1530     // acquire a class-name based lock rather than the class loader object lock.
1531     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1532     JavaCalls::call_virtual(&result,
1533                             class_loader,
1534                             spec_klass,
1535                             vmSymbols::loadClass_name(),
1536                             vmSymbols::string_class_signature(),
1537                             string,
1538                             CHECK_NULL);
1539 
1540     assert(result.get_type() == T_OBJECT, "just checking");
1541     oop obj = (oop) result.get_jobject();
1542 
1543     // Primitive classes return null since forName() can not be
1544     // used to obtain any of the Class objects representing primitives or void
1545     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1546       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1547       // For user defined Java class loaders, check that the name returned is
1548       // the same as that requested.  This check is done for the bootstrap
1549       // loader when parsing the class file.
1550       if (class_name == k->name()) {
1551         return k;
1552       }
1553     }
1554     // Class is not found or has the wrong name, return NULL
1555     return NULL;
1556   }
1557 }
1558 
1559 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1560 
1561   HandleMark hm(THREAD);
1562   ClassLoaderData* loader_data = k->class_loader_data();
1563   Handle class_loader_h(THREAD, loader_data->class_loader());
1564 
1565  // for bootstrap and other parallel classloaders don't acquire lock,
1566  // use placeholder token
1567  // If a parallelCapable class loader calls define_instance_class instead of
1568  // find_or_define_instance_class to get here, we have a timing
1569  // hole with systemDictionary updates and check_constraints
1570  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1571     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1572          compute_loader_lock_object(class_loader_h, THREAD)),
1573          "define called without lock");
1574   }
1575 
1576   // Check class-loading constraints. Throw exception if violation is detected.
1577   // Grabs and releases SystemDictionary_lock
1578   // The check_constraints/find_class call and update_dictionary sequence
1579   // must be "atomic" for a specific class/classloader pair so we never
1580   // define two different instanceKlasses for that class/classloader pair.
1581   // Existing classloaders will call define_instance_class with the
1582   // classloader lock held
1583   // Parallel classloaders will call find_or_define_instance_class
1584   // which will require a token to perform the define class
1585   Symbol*  name_h = k->name();
1586   Dictionary* dictionary = loader_data->dictionary();
1587   unsigned int d_hash = dictionary->compute_hash(name_h);
1588   check_constraints(d_hash, k, class_loader_h, true, CHECK);
1589 
1590   // Register class just loaded with class loader (placed in Vector)
1591   // Note we do this before updating the dictionary, as this can
1592   // fail with an OutOfMemoryError (if it does, we will *not* put this
1593   // class in the dictionary and will not update the class hierarchy).
1594   // JVMTI FollowReferences needs to find the classes this way.
1595   if (k->class_loader() != NULL) {
1596     methodHandle m(THREAD, Universe::loader_addClass_method());
1597     JavaValue result(T_VOID);
1598     JavaCallArguments args(class_loader_h);
1599     args.push_oop(Handle(THREAD, k->java_mirror()));
1600     JavaCalls::call(&result, m, &args, CHECK);
1601   }
1602 
1603   // Add the new class. We need recompile lock during update of CHA.
1604   {
1605     unsigned int p_hash = placeholders()->compute_hash(name_h);
1606     int p_index = placeholders()->hash_to_index(p_hash);
1607 
1608     MutexLocker mu_r(Compile_lock, THREAD);
1609 
1610     // Add to class hierarchy, initialize vtables, and do possible
1611     // deoptimizations.
1612     add_to_hierarchy(k, CHECK); // No exception, but can block
1613 
1614     // Add to systemDictionary - so other classes can see it.
1615     // Grabs and releases SystemDictionary_lock
1616     update_dictionary(d_hash, p_index, p_hash,
1617                       k, class_loader_h, THREAD);
1618   }
1619   k->eager_initialize(THREAD);
1620 
1621   // notify jvmti
1622   if (JvmtiExport::should_post_class_load()) {
1623       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1624       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1625 
1626   }
1627   class_define_event(k, loader_data);
1628 }
1629 
1630 // Support parallel classloading
1631 // All parallel class loaders, including bootstrap classloader
1632 // lock a placeholder entry for this class/class_loader pair
1633 // to allow parallel defines of different classes for this class loader
1634 // With AllowParallelDefine flag==true, in case they do not synchronize around
1635 // FindLoadedClass/DefineClass, calls, we check for parallel
1636 // loading for them, wait if a defineClass is in progress
1637 // and return the initial requestor's results
1638 // This flag does not apply to the bootstrap classloader.
1639 // With AllowParallelDefine flag==false, call through to define_instance_class
1640 // which will throw LinkageError: duplicate class definition.
1641 // False is the requested default.
1642 // For better performance, the class loaders should synchronize
1643 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1644 // potentially waste time reading and parsing the bytestream.
1645 // Note: VM callers should ensure consistency of k/class_name,class_loader
1646 // Be careful when modifying this code: once you have run
1647 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1648 // you need to find_and_remove it before returning.
1649 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1650 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1651                                                                InstanceKlass* k, TRAPS) {
1652 
1653   Symbol*  name_h = k->name(); // passed in class_name may be null
1654   ClassLoaderData* loader_data = class_loader_data(class_loader);
1655   Dictionary* dictionary = loader_data->dictionary();
1656 
1657   unsigned int d_hash = dictionary->compute_hash(name_h);
1658 
1659   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1660   unsigned int p_hash = placeholders()->compute_hash(name_h);
1661   int p_index = placeholders()->hash_to_index(p_hash);
1662   PlaceholderEntry* probe;
1663 
1664   {
1665     MutexLocker mu(SystemDictionary_lock, THREAD);
1666     // First check if class already defined
1667     if (is_parallelDefine(class_loader)) {
1668       InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1669       if (check != NULL) {
1670         return check;
1671       }
1672     }
1673 
1674     // Acquire define token for this class/classloader
1675     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1676     // Wait if another thread defining in parallel
1677     // All threads wait - even those that will throw duplicate class: otherwise
1678     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1679     // if other thread has not finished updating dictionary
1680     while (probe->definer() != NULL) {
1681       SystemDictionary_lock->wait();
1682     }
1683     // Only special cases allow parallel defines and can use other thread's results
1684     // Other cases fall through, and may run into duplicate defines
1685     // caught by finding an entry in the SystemDictionary
1686     if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1687         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1688         SystemDictionary_lock->notify_all();
1689 #ifdef ASSERT
1690         InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1691         assert(check != NULL, "definer missed recording success");
1692 #endif
1693         return probe->instance_klass();
1694     } else {
1695       // This thread will define the class (even if earlier thread tried and had an error)
1696       probe->set_definer(THREAD);
1697     }
1698   }
1699 
1700   define_instance_class(k, THREAD);
1701 
1702   Handle linkage_exception = Handle(); // null handle
1703 
1704   // definer must notify any waiting threads
1705   {
1706     MutexLocker mu(SystemDictionary_lock, THREAD);
1707     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1708     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1709     if (probe != NULL) {
1710       if (HAS_PENDING_EXCEPTION) {
1711         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1712         CLEAR_PENDING_EXCEPTION;
1713       } else {
1714         probe->set_instance_klass(k);
1715       }
1716       probe->set_definer(NULL);
1717       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1718       SystemDictionary_lock->notify_all();
1719     }
1720   }
1721 
1722   // Can't throw exception while holding lock due to rank ordering
1723   if (linkage_exception() != NULL) {
1724     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1725   }
1726 
1727   return k;
1728 }
1729 
1730 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1731   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1732   if (class_loader.is_null()) {
1733     return Handle(THREAD, _system_loader_lock_obj);
1734   } else {
1735     return class_loader;
1736   }
1737 }
1738 
1739 // This method is added to check how often we have to wait to grab loader
1740 // lock. The results are being recorded in the performance counters defined in
1741 // ClassLoader::_sync_systemLoaderLockContentionRate and
1742 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1743 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1744   if (!UsePerfData) {
1745     return;
1746   }
1747 
1748   assert(!loader_lock.is_null(), "NULL lock object");
1749 
1750   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1751       == ObjectSynchronizer::owner_other) {
1752     // contention will likely happen, so increment the corresponding
1753     // contention counter.
1754     if (oopDesc::equals(loader_lock(), _system_loader_lock_obj)) {
1755       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1756     } else {
1757       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1758     }
1759   }
1760 }
1761 
1762 // ----------------------------------------------------------------------------
1763 // Lookup
1764 
1765 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1766                                             Symbol* class_name,
1767                                             Dictionary* dictionary) {
1768   assert_locked_or_safepoint(SystemDictionary_lock);
1769   int index = dictionary->hash_to_index(hash);
1770   return dictionary->find_class(index, hash, class_name);
1771 }
1772 
1773 
1774 // Basic find on classes in the midst of being loaded
1775 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1776                                            ClassLoaderData* loader_data) {
1777   assert_locked_or_safepoint(SystemDictionary_lock);
1778   unsigned int p_hash = placeholders()->compute_hash(class_name);
1779   int p_index = placeholders()->hash_to_index(p_hash);
1780   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1781 }
1782 
1783 
1784 // Used for assertions and verification only
1785 // Precalculating the hash and index is an optimization because there are many lookups
1786 // before adding the class.
1787 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1788   assert_locked_or_safepoint(SystemDictionary_lock);
1789   #ifndef ASSERT
1790   guarantee(VerifyBeforeGC      ||
1791             VerifyDuringGC      ||
1792             VerifyBeforeExit    ||
1793             VerifyDuringStartup ||
1794             VerifyAfterGC, "too expensive");
1795   #endif
1796 
1797   Dictionary* dictionary = loader_data->dictionary();
1798   unsigned int d_hash = dictionary->compute_hash(class_name);
1799   return find_class(d_hash, class_name, dictionary);
1800 }
1801 
1802 
1803 // ----------------------------------------------------------------------------
1804 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1805 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1806 // before a new class is used.
1807 
1808 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1809   assert(k != NULL, "just checking");
1810   assert_locked_or_safepoint(Compile_lock);
1811 
1812   // Link into hierachy. Make sure the vtables are initialized before linking into
1813   k->append_to_sibling_list();                    // add to superklass/sibling list
1814   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1815   k->set_init_state(InstanceKlass::loaded);
1816   // Now flush all code that depended on old class hierarchy.
1817   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1818   // Also, first reinitialize vtable because it may have gotten out of synch
1819   // while the new class wasn't connected to the class hierarchy.
1820   CodeCache::flush_dependents_on(k);
1821 }
1822 
1823 // ----------------------------------------------------------------------------
1824 // GC support
1825 
1826 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1827   roots_oops_do(blk, NULL);
1828 }
1829 
1830 
1831 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1832 // Note: anonymous classes are not in the SD.
1833 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1834                                     GCTimer* gc_timer,
1835                                     bool do_cleaning) {
1836 
1837   {
1838     GCTraceTime(Debug, gc, phases) t("SystemDictionary WeakHandle cleaning", gc_timer);
1839     vm_weak_oop_storage()->weak_oops_do(is_alive, &do_nothing_cl);
1840   }
1841 
1842   bool unloading_occurred;
1843   {
1844     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1845 
1846     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1847     unloading_occurred = ClassLoaderDataGraph::do_unloading(do_cleaning);
1848   }
1849 
1850   if (unloading_occurred) {
1851     GCTraceTime(Debug, gc, phases) t("Dictionary", gc_timer);
1852     constraints()->purge_loader_constraints();
1853     resolution_errors()->purge_resolution_errors();
1854   }
1855 
1856   {
1857     GCTraceTime(Debug, gc, phases) t("ProtectionDomainCacheTable", gc_timer);
1858     // Oops referenced by the protection domain cache table may get unreachable independently
1859     // of the class loader (eg. cached protection domain oops). So we need to
1860     // explicitly unlink them here.
1861     _pd_cache_table->unlink();
1862   }
1863 
1864   if (do_cleaning) {
1865     GCTraceTime(Debug, gc, phases) t("ResolvedMethodTable", gc_timer);
1866     ResolvedMethodTable::unlink();
1867   }
1868 
1869   return unloading_occurred;
1870 }
1871 
1872 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1873   strong->do_oop(&_java_system_loader);
1874   strong->do_oop(&_java_platform_loader);
1875   strong->do_oop(&_system_loader_lock_obj);
1876   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1877 
1878   // Do strong roots marking if the closures are the same.
1879   if (strong == weak || !ClassUnloading) {
1880     // Only the protection domain oops contain references into the heap. Iterate
1881     // over all of them.
1882     vm_weak_oop_storage()->oops_do(strong);
1883   } else {
1884    if (weak != NULL) {
1885      vm_weak_oop_storage()->oops_do(weak);
1886    }
1887   }
1888 
1889   // Visit extra methods
1890   invoke_method_table()->oops_do(strong);
1891 }
1892 
1893 void SystemDictionary::oops_do(OopClosure* f) {
1894   f->do_oop(&_java_system_loader);
1895   f->do_oop(&_java_platform_loader);
1896   f->do_oop(&_system_loader_lock_obj);
1897   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1898 
1899   // Visit extra methods
1900   invoke_method_table()->oops_do(f);
1901 
1902   vm_weak_oop_storage()->oops_do(f);
1903 }
1904 
1905 // CDS: scan and relocate all classes in the system dictionary.
1906 void SystemDictionary::classes_do(MetaspaceClosure* it) {
1907   ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(it);
1908 }
1909 
1910 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1911 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1912   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1913     it->push(well_known_klass_addr((WKID)id));
1914   }
1915 }
1916 
1917 void SystemDictionary::methods_do(void f(Method*)) {
1918   // Walk methods in loaded classes
1919   ClassLoaderDataGraph::methods_do(f);
1920   // Walk method handle intrinsics
1921   invoke_method_table()->methods_do(f);
1922 }
1923 
1924 class RemoveClassesClosure : public CLDClosure {
1925   public:
1926     void do_cld(ClassLoaderData* cld) {
1927       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
1928         cld->dictionary()->remove_classes_in_error_state();
1929       }
1930     }
1931 };
1932 
1933 void SystemDictionary::remove_classes_in_error_state() {
1934   ClassLoaderData::the_null_class_loader_data()->dictionary()->remove_classes_in_error_state();
1935   RemoveClassesClosure rcc;
1936   ClassLoaderDataGraph::cld_do(&rcc);
1937 }
1938 
1939 // ----------------------------------------------------------------------------
1940 // Lazily load klasses
1941 
1942 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1943   // if multiple threads calling this function, only one thread will load
1944   // the class.  The other threads will find the loaded version once the
1945   // class is loaded.
1946   Klass* aos = _abstract_ownable_synchronizer_klass;
1947   if (aos == NULL) {
1948     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1949     // Force a fence to prevent any read before the write completes
1950     OrderAccess::fence();
1951     _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
1952   }
1953 }
1954 
1955 // ----------------------------------------------------------------------------
1956 // Initialization
1957 
1958 void SystemDictionary::initialize(TRAPS) {
1959   // Allocate arrays
1960   _placeholders        = new PlaceholderTable(_placeholder_table_size);
1961   _number_of_modifications = 0;
1962   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1963   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1964   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1965   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1966 
1967   // Allocate private object used as system class loader lock
1968   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1969   // Initialize basic classes
1970   initialize_preloaded_classes(CHECK);
1971 
1972   CDS_ONLY(SystemDictionaryShared::initialize_locks();)
1973 }
1974 
1975 // Compact table of directions on the initialization of klasses:
1976 static const short wk_init_info[] = {
1977   #define WK_KLASS_INIT_INFO(name, symbol, option) \
1978     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1979           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1980       | (int)SystemDictionary::option ),
1981   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1982   #undef WK_KLASS_INIT_INFO
1983   0
1984 };
1985 
1986 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1987   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1988   int  info = wk_init_info[id - FIRST_WKID];
1989   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
1990   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1991   InstanceKlass** klassp = &_well_known_klasses[id];
1992 
1993   bool must_load;
1994 #if INCLUDE_JVMCI
1995   if (EnableJVMCI) {
1996     // If JVMCI is enabled we require its classes to be found.
1997     must_load = (init_opt < SystemDictionary::Opt) || (init_opt == SystemDictionary::Jvmci);
1998   } else
1999 #endif
2000   {
2001     must_load = (init_opt < SystemDictionary::Opt);
2002   }
2003 
2004   if ((*klassp) == NULL) {
2005     Klass* k;
2006     if (must_load) {
2007       k = resolve_or_fail(symbol, true, CHECK_0); // load required class
2008     } else {
2009       k = resolve_or_null(symbol,       CHECK_0); // load optional klass
2010     }
2011     (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
2012   }
2013   return ((*klassp) != NULL);
2014 }
2015 
2016 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
2017   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
2018   for (int id = (int)start_id; id < (int)limit_id; id++) {
2019     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2020     int info = wk_init_info[id - FIRST_WKID];
2021     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
2022     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
2023 
2024     initialize_wk_klass((WKID)id, opt, CHECK);
2025   }
2026 
2027   // move the starting value forward to the limit:
2028   start_id = limit_id;
2029 }
2030 
2031 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
2032   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
2033 
2034   // Create the ModuleEntry for java.base.  This call needs to be done here,
2035   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
2036   ClassLoader::classLoader_init2(CHECK);
2037 
2038   // Preload commonly used klasses
2039   WKID scan = FIRST_WKID;
2040   // first do Object, then String, Class
2041 #if INCLUDE_CDS
2042   if (UseSharedSpaces) {
2043     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
2044     // Initialize the constant pool for the Object_class
2045     Object_klass()->constants()->restore_unshareable_info(CHECK);
2046     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2047   } else
2048 #endif
2049   {
2050     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2051   }
2052 
2053   // Calculate offsets for String and Class classes since they are loaded and
2054   // can be used after this point.
2055   java_lang_String::compute_offsets();
2056   java_lang_Class::compute_offsets();
2057 
2058   // Fixup mirrors for classes loaded before java.lang.Class.
2059   // These calls iterate over the objects currently in the perm gen
2060   // so calling them at this point is matters (not before when there
2061   // are fewer objects and not later after there are more objects
2062   // in the perm gen.
2063   Universe::initialize_basic_type_mirrors(CHECK);
2064   Universe::fixup_mirrors(CHECK);
2065 
2066   // do a bunch more:
2067   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2068 
2069   // Preload ref klasses and set reference types
2070   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2071   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2072 
2073   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2074   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2075   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2076   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2077   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2078 
2079   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(ReferenceQueue_klass), scan, CHECK);
2080 
2081   // JSR 292 classes
2082   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2083   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2084   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
2085   initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
2086   initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
2087 
2088   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2089   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2090   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2091   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2092   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2093   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2094   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2095   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2096   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2097   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2098 
2099   { // Compute whether we should use checkPackageAccess or NOT
2100     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2101     _has_checkPackageAccess = (method != NULL);
2102   }
2103 }
2104 
2105 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2106 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2107 BasicType SystemDictionary::box_klass_type(Klass* k) {
2108   assert(k != NULL, "");
2109   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2110     if (_box_klasses[i] == k)
2111       return (BasicType)i;
2112   }
2113   return T_OBJECT;
2114 }
2115 
2116 // Constraints on class loaders. The details of the algorithm can be
2117 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2118 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2119 // that the dictionary needs to maintain a set of contraints that
2120 // must be satisfied by all classes in the dictionary.
2121 // if defining is true, then LinkageError if already in dictionary
2122 // if initiating loader, then ok if InstanceKlass matches existing entry
2123 
2124 void SystemDictionary::check_constraints(unsigned int d_hash,
2125                                          InstanceKlass* k,
2126                                          Handle class_loader,
2127                                          bool defining,
2128                                          TRAPS) {
2129   ResourceMark rm(THREAD);
2130   stringStream ss;
2131   bool throwException = false;
2132 
2133   const char *linkage_error1 = NULL;
2134   const char *linkage_error2 = NULL;
2135   const char *linkage_error3 = "";
2136   // Remember the loader of the similar class that is already loaded.
2137   const char *existing_klass_loader_name = "";
2138 
2139   {
2140     Symbol*  name  = k->name();
2141     ClassLoaderData *loader_data = class_loader_data(class_loader);
2142 
2143     MutexLocker mu(SystemDictionary_lock, THREAD);
2144 
2145     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2146     if (check != NULL) {
2147       // If different InstanceKlass - duplicate class definition,
2148       // else - ok, class loaded by a different thread in parallel.
2149       // We should only have found it if it was done loading and ok to use.
2150       // The dictionary only holds instance classes, placeholders
2151       // also hold array classes.
2152 
2153       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2154       if ((defining == true) || (k != check)) {
2155         throwException = true;
2156         ss.print("loader %s", java_lang_ClassLoader::describe_external(class_loader()));
2157         ss.print(" attempted duplicate %s definition for %s.",
2158                  k->external_kind(), k->external_name());
2159       } else {
2160         return;
2161       }
2162     }
2163 
2164 #ifdef ASSERT
2165     Symbol* ph_check = find_placeholder(name, loader_data);
2166     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2167 #endif
2168 
2169     if (throwException == false) {
2170       if (constraints()->check_or_update(k, class_loader, name) == false) {
2171         throwException = true;
2172         ss.print("loader constraint violation: loader %s",
2173                  java_lang_ClassLoader::describe_external(class_loader()));
2174         ss.print(" wants to load %s %s.",
2175                  k->external_kind(), k->external_name());
2176         Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2177         if (existing_klass->class_loader() != class_loader()) {
2178           ss.print(" A different %s with the same name was previously loaded by %s.",
2179                    existing_klass->external_kind(),
2180                    java_lang_ClassLoader::describe_external(existing_klass->class_loader()));
2181         }
2182       }
2183     }
2184   }
2185 
2186   // Throw error now if needed (cannot throw while holding
2187   // SystemDictionary_lock because of rank ordering)
2188   if (throwException == true) {
2189     THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2190   }
2191 }
2192 
2193 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2194 // have been called.
2195 void SystemDictionary::update_dictionary(unsigned int d_hash,
2196                                          int p_index, unsigned int p_hash,
2197                                          InstanceKlass* k,
2198                                          Handle class_loader,
2199                                          TRAPS) {
2200   // Compile_lock prevents systemDictionary updates during compilations
2201   assert_locked_or_safepoint(Compile_lock);
2202   Symbol*  name  = k->name();
2203   ClassLoaderData *loader_data = class_loader_data(class_loader);
2204 
2205   {
2206     MutexLocker mu1(SystemDictionary_lock, THREAD);
2207 
2208     // See whether biased locking is enabled and if so set it for this
2209     // klass.
2210     // Note that this must be done past the last potential blocking
2211     // point / safepoint. We enable biased locking lazily using a
2212     // VM_Operation to iterate the SystemDictionary and installing the
2213     // biasable mark word into each InstanceKlass's prototype header.
2214     // To avoid race conditions where we accidentally miss enabling the
2215     // optimization for one class in the process of being added to the
2216     // dictionary, we must not safepoint after the test of
2217     // BiasedLocking::enabled().
2218     if (UseBiasedLocking && BiasedLocking::enabled()) {
2219       // Set biased locking bit for all loaded classes; it will be
2220       // cleared if revocation occurs too often for this type
2221       // NOTE that we must only do this when the class is initally
2222       // defined, not each time it is referenced from a new class loader
2223       if (oopDesc::equals(k->class_loader(), class_loader())) {
2224         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2225       }
2226     }
2227 
2228     // Make a new dictionary entry.
2229     Dictionary* dictionary = loader_data->dictionary();
2230     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2231     if (sd_check == NULL) {
2232       dictionary->add_klass(d_hash, name, k);
2233       notice_modification();
2234     }
2235   #ifdef ASSERT
2236     sd_check = find_class(d_hash, name, dictionary);
2237     assert (sd_check != NULL, "should have entry in dictionary");
2238     // Note: there may be a placeholder entry: for circularity testing
2239     // or for parallel defines
2240   #endif
2241     SystemDictionary_lock->notify_all();
2242   }
2243 }
2244 
2245 
2246 // Try to find a class name using the loader constraints.  The
2247 // loader constraints might know about a class that isn't fully loaded
2248 // yet and these will be ignored.
2249 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2250                     Symbol* class_name, Handle class_loader, TRAPS) {
2251 
2252   // First see if it has been loaded directly.
2253   // Force the protection domain to be null.  (This removes protection checks.)
2254   Handle no_protection_domain;
2255   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2256                                               no_protection_domain, CHECK_NULL);
2257   if (klass != NULL)
2258     return klass;
2259 
2260   // Now look to see if it has been loaded elsewhere, and is subject to
2261   // a loader constraint that would require this loader to return the
2262   // klass that is already loaded.
2263   if (FieldType::is_array(class_name)) {
2264     // For array classes, their Klass*s are not kept in the
2265     // constraint table. The element Klass*s are.
2266     FieldArrayInfo fd;
2267     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2268     if (t != T_OBJECT) {
2269       klass = Universe::typeArrayKlassObj(t);
2270     } else {
2271       MutexLocker mu(SystemDictionary_lock, THREAD);
2272       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2273     }
2274     // If element class already loaded, allocate array klass
2275     if (klass != NULL) {
2276       klass = klass->array_klass_or_null(fd.dimension());
2277     }
2278   } else {
2279     MutexLocker mu(SystemDictionary_lock, THREAD);
2280     // Non-array classes are easy: simply check the constraint table.
2281     klass = constraints()->find_constrained_klass(class_name, class_loader);
2282   }
2283 
2284   return klass;
2285 }
2286 
2287 
2288 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2289                                              Handle class_loader1,
2290                                              Handle class_loader2,
2291                                              Thread* THREAD) {
2292   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2293   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2294 
2295   Symbol* constraint_name = NULL;
2296   if (!FieldType::is_array(class_name)) {
2297     constraint_name = class_name;
2298   } else {
2299     // For array classes, their Klass*s are not kept in the
2300     // constraint table. The element classes are.
2301     FieldArrayInfo fd;
2302     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2303     // primitive types always pass
2304     if (t != T_OBJECT) {
2305       return true;
2306     } else {
2307       constraint_name = fd.object_key();
2308     }
2309   }
2310 
2311   Dictionary* dictionary1 = loader_data1->dictionary();
2312   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2313 
2314   Dictionary* dictionary2 = loader_data2->dictionary();
2315   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2316 
2317   {
2318     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2319     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2320     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2321     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2322                                     klass2, class_loader2);
2323   }
2324 }
2325 
2326 // Add entry to resolution error table to record the error when the first
2327 // attempt to resolve a reference to a class has failed.
2328 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2329                                             Symbol* error, Symbol* message) {
2330   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2331   int index = resolution_errors()->hash_to_index(hash);
2332   {
2333     MutexLocker ml(SystemDictionary_lock, Thread::current());
2334     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2335   }
2336 }
2337 
2338 // Delete a resolution error for RedefineClasses for a constant pool is going away
2339 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2340   resolution_errors()->delete_entry(pool);
2341 }
2342 
2343 // Lookup resolution error table. Returns error if found, otherwise NULL.
2344 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2345                                                 Symbol** message) {
2346   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2347   int index = resolution_errors()->hash_to_index(hash);
2348   {
2349     MutexLocker ml(SystemDictionary_lock, Thread::current());
2350     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2351     if (entry != NULL) {
2352       *message = entry->message();
2353       return entry->error();
2354     } else {
2355       return NULL;
2356     }
2357   }
2358 }
2359 
2360 
2361 // Signature constraints ensure that callers and callees agree about
2362 // the meaning of type names in their signatures.  This routine is the
2363 // intake for constraints.  It collects them from several places:
2364 //
2365 //  * LinkResolver::resolve_method (if check_access is true) requires
2366 //    that the resolving class (the caller) and the defining class of
2367 //    the resolved method (the callee) agree on each type in the
2368 //    method's signature.
2369 //
2370 //  * LinkResolver::resolve_interface_method performs exactly the same
2371 //    checks.
2372 //
2373 //  * LinkResolver::resolve_field requires that the constant pool
2374 //    attempting to link to a field agree with the field's defining
2375 //    class about the type of the field signature.
2376 //
2377 //  * klassVtable::initialize_vtable requires that, when a class
2378 //    overrides a vtable entry allocated by a superclass, that the
2379 //    overriding method (i.e., the callee) agree with the superclass
2380 //    on each type in the method's signature.
2381 //
2382 //  * klassItable::initialize_itable requires that, when a class fills
2383 //    in its itables, for each non-abstract method installed in an
2384 //    itable, the method (i.e., the callee) agree with the interface
2385 //    on each type in the method's signature.
2386 //
2387 // All those methods have a boolean (check_access, checkconstraints)
2388 // which turns off the checks.  This is used from specialized contexts
2389 // such as bootstrapping, dumping, and debugging.
2390 //
2391 // No direct constraint is placed between the class and its
2392 // supertypes.  Constraints are only placed along linked relations
2393 // between callers and callees.  When a method overrides or implements
2394 // an abstract method in a supertype (superclass or interface), the
2395 // constraints are placed as if the supertype were the caller to the
2396 // overriding method.  (This works well, since callers to the
2397 // supertype have already established agreement between themselves and
2398 // the supertype.)  As a result of all this, a class can disagree with
2399 // its supertype about the meaning of a type name, as long as that
2400 // class neither calls a relevant method of the supertype, nor is
2401 // called (perhaps via an override) from the supertype.
2402 //
2403 //
2404 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2405 //
2406 // Make sure all class components (including arrays) in the given
2407 // signature will be resolved to the same class in both loaders.
2408 // Returns the name of the type that failed a loader constraint check, or
2409 // NULL if no constraint failed.  No exception except OOME is thrown.
2410 // Arrays are not added to the loader constraint table, their elements are.
2411 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2412                                                Handle loader1, Handle loader2,
2413                                                bool is_method, TRAPS)  {
2414   // Nothing to do if loaders are the same.
2415   if (oopDesc::equals(loader1(), loader2())) {
2416     return NULL;
2417   }
2418 
2419   SignatureStream sig_strm(signature, is_method);
2420   while (!sig_strm.is_done()) {
2421     if (sig_strm.is_object()) {
2422       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2423       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2424         return sig;
2425       }
2426     }
2427     sig_strm.next();
2428   }
2429   return NULL;
2430 }
2431 
2432 
2433 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2434                                                             Symbol* signature,
2435                                                             TRAPS) {
2436   methodHandle empty;
2437   assert(MethodHandles::is_signature_polymorphic(iid) &&
2438          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2439          iid != vmIntrinsics::_invokeGeneric,
2440          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2441 
2442   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2443   int          index = invoke_method_table()->hash_to_index(hash);
2444   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2445   methodHandle m;
2446   if (spe == NULL || spe->method() == NULL) {
2447     spe = NULL;
2448     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2449     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2450     if (!Arguments::is_interpreter_only()) {
2451       // Generate a compiled form of the MH intrinsic.
2452       AdapterHandlerLibrary::create_native_wrapper(m);
2453       // Check if have the compiled code.
2454       if (!m->has_compiled_code()) {
2455         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2456                    "Out of space in CodeCache for method handle intrinsic", empty);
2457       }
2458     }
2459     // Now grab the lock.  We might have to throw away the new method,
2460     // if a racing thread has managed to install one at the same time.
2461     {
2462       MutexLocker ml(SystemDictionary_lock, THREAD);
2463       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2464       if (spe == NULL)
2465         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2466       if (spe->method() == NULL)
2467         spe->set_method(m());
2468     }
2469   }
2470 
2471   assert(spe != NULL && spe->method() != NULL, "");
2472   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2473          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2474          "MH intrinsic invariant");
2475   return spe->method();
2476 }
2477 
2478 // Helper for unpacking the return value from linkMethod and linkCallSite.
2479 static methodHandle unpack_method_and_appendix(Handle mname,
2480                                                Klass* accessing_klass,
2481                                                objArrayHandle appendix_box,
2482                                                Handle* appendix_result,
2483                                                TRAPS) {
2484   methodHandle empty;
2485   if (mname.not_null()) {
2486     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2487     if (m != NULL) {
2488       oop appendix = appendix_box->obj_at(0);
2489       if (TraceMethodHandles) {
2490     #ifndef PRODUCT
2491         ttyLocker ttyl;
2492         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2493         m->print();
2494         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2495         tty->cr();
2496     #endif //PRODUCT
2497       }
2498       (*appendix_result) = Handle(THREAD, appendix);
2499       // the target is stored in the cpCache and if a reference to this
2500       // MemberName is dropped we need a way to make sure the
2501       // class_loader containing this method is kept alive.
2502       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2503       this_key->record_dependency(m->method_holder());
2504       return methodHandle(THREAD, m);
2505     }
2506   }
2507   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2508   return empty;
2509 }
2510 
2511 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2512                                                           Symbol* name,
2513                                                           Symbol* signature,
2514                                                           Klass* accessing_klass,
2515                                                           Handle *appendix_result,
2516                                                           Handle *method_type_result,
2517                                                           TRAPS) {
2518   methodHandle empty;
2519   assert(THREAD->can_call_java() ,"");
2520   Handle method_type =
2521     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2522 
2523   int ref_kind = JVM_REF_invokeVirtual;
2524   oop name_oop = StringTable::intern(name, CHECK_(empty));
2525   Handle name_str (THREAD, name_oop);
2526   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2527   assert(appendix_box->obj_at(0) == NULL, "");
2528 
2529   // This should not happen.  JDK code should take care of that.
2530   if (accessing_klass == NULL || method_type.is_null()) {
2531     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2532   }
2533 
2534   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2535   JavaCallArguments args;
2536   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2537   args.push_int(ref_kind);
2538   args.push_oop(Handle(THREAD, klass->java_mirror()));
2539   args.push_oop(name_str);
2540   args.push_oop(method_type);
2541   args.push_oop(appendix_box);
2542   JavaValue result(T_OBJECT);
2543   JavaCalls::call_static(&result,
2544                          SystemDictionary::MethodHandleNatives_klass(),
2545                          vmSymbols::linkMethod_name(),
2546                          vmSymbols::linkMethod_signature(),
2547                          &args, CHECK_(empty));
2548   Handle mname(THREAD, (oop) result.get_jobject());
2549   (*method_type_result) = method_type;
2550   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2551 }
2552 
2553 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2554 // We must ensure that all class loaders everywhere will reach this class, for any client.
2555 // This is a safe bet for public classes in java.lang, such as Object and String.
2556 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2557 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2558 static bool is_always_visible_class(oop mirror) {
2559   Klass* klass = java_lang_Class::as_Klass(mirror);
2560   if (klass->is_objArray_klass()) {
2561     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2562   }
2563   if (klass->is_typeArray_klass()) {
2564     return true; // primitive array
2565   }
2566   assert(klass->is_instance_klass(), "%s", klass->external_name());
2567   return klass->is_public() &&
2568          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2569           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2570 }
2571 
2572 
2573 // Return the Java mirror (java.lang.Class instance) for a single-character
2574 // descriptor.  This result, when available, is the same as produced by the
2575 // heavier API point of the same name that takes a Symbol.
2576 oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
2577   return java_lang_Class::primitive_mirror(char2type(signature_char));
2578 }
2579 
2580 // Find or construct the Java mirror (java.lang.Class instance) for a
2581 // for the given field type signature, as interpreted relative to the
2582 // given class loader.  Handles primitives, void, references, arrays,
2583 // and all other reflectable types, except method types.
2584 // N.B.  Code in reflection should use this entry point.
2585 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2586                                                    Klass* accessing_klass,
2587                                                    Handle class_loader,
2588                                                    Handle protection_domain,
2589                                                    SignatureStream::FailureMode failure_mode,
2590                                                    TRAPS) {
2591   Handle empty;
2592 
2593   assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2594          "one or the other, or perhaps neither");
2595 
2596   Symbol* type = signature;
2597 
2598   // What we have here must be a valid field descriptor,
2599   // and all valid field descriptors are supported.
2600   // Produce the same java.lang.Class that reflection reports.
2601   if (type->utf8_length() == 1) {
2602 
2603     // It's a primitive.  (Void has a primitive mirror too.)
2604     char ch = (char) type->byte_at(0);
2605     assert(is_java_primitive(char2type(ch)) || ch == 'V', "");
2606     return Handle(THREAD, find_java_mirror_for_type(ch));
2607 
2608   } else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
2609 
2610     // It's a reference type.
2611     if (accessing_klass != NULL) {
2612       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2613       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2614     }
2615     Klass* constant_type_klass;
2616     if (failure_mode == SignatureStream::ReturnNull) {
2617       constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
2618                                             CHECK_(empty));
2619     } else {
2620       bool throw_error = (failure_mode == SignatureStream::NCDFError);
2621       constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
2622                                             throw_error, CHECK_(empty));
2623     }
2624     if (constant_type_klass == NULL) {
2625       return Handle();  // report failure this way
2626     }
2627     Handle mirror(THREAD, constant_type_klass->java_mirror());
2628 
2629     // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2630     if (accessing_klass != NULL) {
2631       Klass* sel_klass = constant_type_klass;
2632       bool fold_type_to_class = true;
2633       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2634                                               fold_type_to_class, CHECK_(empty));
2635     }
2636 
2637     return mirror;
2638 
2639   }
2640 
2641   // Fall through to an error.
2642   assert(false, "unsupported mirror syntax");
2643   THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2644 }
2645 
2646 
2647 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2648 // signature, as interpreted relative to the given class loader.
2649 // Because of class loader constraints, all method handle usage must be
2650 // consistent with this loader.
2651 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2652                                                  Klass* accessing_klass,
2653                                                  TRAPS) {
2654   Handle empty;
2655   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2656   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2657   int          index = invoke_method_table()->hash_to_index(hash);
2658   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2659   if (spe != NULL && spe->method_type() != NULL) {
2660     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2661     return Handle(THREAD, spe->method_type());
2662   } else if (!THREAD->can_call_java()) {
2663     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2664     return Handle();  // do not attempt from within compiler, unless it was cached
2665   }
2666 
2667   Handle class_loader, protection_domain;
2668   if (accessing_klass != NULL) {
2669     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2670     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2671   }
2672   bool can_be_cached = true;
2673   int npts = ArgumentCount(signature).size();
2674   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2675   int arg = 0;
2676   Handle rt; // the return type from the signature
2677   ResourceMark rm(THREAD);
2678   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2679     oop mirror = NULL;
2680     if (can_be_cached) {
2681       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2682       mirror = ss.as_java_mirror(Handle(), Handle(),
2683                                  SignatureStream::ReturnNull, CHECK_(empty));
2684       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2685         // Fall back to accessing_klass context.
2686         can_be_cached = false;
2687       }
2688     }
2689     if (!can_be_cached) {
2690       // Resolve, throwing a real error if it doesn't work.
2691       mirror = ss.as_java_mirror(class_loader, protection_domain,
2692                                  SignatureStream::NCDFError, CHECK_(empty));
2693     }
2694     assert(mirror != NULL, "%s", ss.as_symbol(THREAD)->as_C_string());
2695     if (ss.at_return_type())
2696       rt = Handle(THREAD, mirror);
2697     else
2698       pts->obj_at_put(arg++, mirror);
2699 
2700     // Check accessibility.
2701     if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2702       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2703       mirror = NULL;  // safety
2704       // Emulate ConstantPool::verify_constant_pool_resolve.
2705       bool fold_type_to_class = true;
2706       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2707                                               fold_type_to_class, CHECK_(empty));
2708     }
2709   }
2710   assert(arg == npts, "");
2711 
2712   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2713   JavaCallArguments args(Handle(THREAD, rt()));
2714   args.push_oop(pts);
2715   JavaValue result(T_OBJECT);
2716   JavaCalls::call_static(&result,
2717                          SystemDictionary::MethodHandleNatives_klass(),
2718                          vmSymbols::findMethodHandleType_name(),
2719                          vmSymbols::findMethodHandleType_signature(),
2720                          &args, CHECK_(empty));
2721   Handle method_type(THREAD, (oop) result.get_jobject());
2722 
2723   if (can_be_cached) {
2724     // We can cache this MethodType inside the JVM.
2725     MutexLocker ml(SystemDictionary_lock, THREAD);
2726     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2727     if (spe == NULL)
2728       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2729     if (spe->method_type() == NULL) {
2730       spe->set_method_type(method_type());
2731     }
2732   }
2733 
2734   // report back to the caller with the MethodType
2735   return method_type;
2736 }
2737 
2738 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2739                                                 Klass* accessing_klass,
2740                                                 TRAPS) {
2741   Handle empty;
2742   ResourceMark rm(THREAD);
2743   SignatureStream ss(signature, /*is_method=*/ false);
2744   if (!ss.is_done()) {
2745     Handle class_loader, protection_domain;
2746     if (accessing_klass != NULL) {
2747       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2748       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2749     }
2750     oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2751     ss.next();
2752     if (ss.is_done()) {
2753       return Handle(THREAD, mirror);
2754     }
2755   }
2756   return empty;
2757 }
2758 
2759 // Ask Java code to find or construct a method handle constant.
2760 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2761                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2762                                                      Klass* callee,
2763                                                      Symbol* name,
2764                                                      Symbol* signature,
2765                                                      TRAPS) {
2766   Handle empty;
2767   if (caller == NULL) {
2768     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2769   }
2770   Handle name_str      = java_lang_String::create_from_symbol(name,      CHECK_(empty));
2771   Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2772 
2773   // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2774   Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2775   java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2776   java_lang_invoke_MemberName::set_name (mname(), name_str());
2777   java_lang_invoke_MemberName::set_type (mname(), signature_str());
2778   java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2779 
2780   if (ref_kind == JVM_REF_invokeVirtual &&
2781       callee->name() == vmSymbols::java_lang_invoke_MethodHandle() &&
2782       (name == vmSymbols::invoke_name() || name == vmSymbols::invokeExact_name())) {
2783     // Skip resolution for j.l.i.MethodHandle.invoke()/invokeExact().
2784     // They are public signature polymorphic methods, but require appendix argument
2785     // which MemberName resolution doesn't handle. There's special logic on JDK side to handle them
2786     // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2787   } else {
2788     MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2789   }
2790 
2791   // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2792   Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2793 
2794   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2795   JavaCallArguments args;
2796   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2797   args.push_int(ref_kind);
2798   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2799   args.push_oop(name_str);
2800   args.push_oop(type);
2801   JavaValue result(T_OBJECT);
2802   JavaCalls::call_static(&result,
2803                          SystemDictionary::MethodHandleNatives_klass(),
2804                          vmSymbols::linkMethodHandleConstant_name(),
2805                          vmSymbols::linkMethodHandleConstant_signature(),
2806                          &args, CHECK_(empty));
2807   return Handle(THREAD, (oop) result.get_jobject());
2808 }
2809 
2810 // Ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry
2811 Handle SystemDictionary::link_dynamic_constant(Klass* caller,
2812                                                int condy_index,
2813                                                Handle bootstrap_specifier,
2814                                                Symbol* name,
2815                                                Symbol* type,
2816                                                TRAPS) {
2817   Handle empty;
2818   Handle bsm, info;
2819   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2820     bsm = bootstrap_specifier;
2821   } else {
2822     assert(bootstrap_specifier->is_objArray(), "");
2823     objArrayOop args = (objArrayOop) bootstrap_specifier();
2824     assert(args->length() == 2, "");
2825     bsm  = Handle(THREAD, args->obj_at(0));
2826     info = Handle(THREAD, args->obj_at(1));
2827   }
2828   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2829             "caller must supply a valid BSM");
2830 
2831   // This should not happen.  JDK code should take care of that.
2832   if (caller == NULL) {
2833     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad dynamic constant", empty);
2834   }
2835 
2836   Handle constant_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2837 
2838   // Resolve the constant type in the context of the caller class
2839   Handle type_mirror = find_java_mirror_for_type(type, caller, SignatureStream::NCDFError,
2840                                                  CHECK_(empty));
2841 
2842   // call java.lang.invoke.MethodHandleNatives::linkConstantDyanmic(caller, condy_index, bsm, type, info)
2843   JavaCallArguments args;
2844   args.push_oop(Handle(THREAD, caller->java_mirror()));
2845   args.push_int(condy_index);
2846   args.push_oop(bsm);
2847   args.push_oop(constant_name);
2848   args.push_oop(type_mirror);
2849   args.push_oop(info);
2850   JavaValue result(T_OBJECT);
2851   JavaCalls::call_static(&result,
2852                          SystemDictionary::MethodHandleNatives_klass(),
2853                          vmSymbols::linkDynamicConstant_name(),
2854                          vmSymbols::linkDynamicConstant_signature(),
2855                          &args, CHECK_(empty));
2856 
2857   return Handle(THREAD, (oop) result.get_jobject());
2858 }
2859 
2860 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2861 // name and signature, as interpreted relative to the given class loader.
2862 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller,
2863                                                               int indy_index,
2864                                                               Handle bootstrap_specifier,
2865                                                               Symbol* name,
2866                                                               Symbol* type,
2867                                                               Handle *appendix_result,
2868                                                               Handle *method_type_result,
2869                                                               TRAPS) {
2870   methodHandle empty;
2871   Handle bsm, info;
2872   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2873     bsm = bootstrap_specifier;
2874   } else {
2875     objArrayOop args = (objArrayOop) bootstrap_specifier();
2876     assert(args->length() == 2, "");
2877     bsm  = Handle(THREAD, args->obj_at(0));
2878     info = Handle(THREAD, args->obj_at(1));
2879   }
2880   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2881             "caller must supply a valid BSM");
2882 
2883   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2884   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2885 
2886   // This should not happen.  JDK code should take care of that.
2887   if (caller == NULL || method_type.is_null()) {
2888     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2889   }
2890 
2891   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2892   assert(appendix_box->obj_at(0) == NULL, "");
2893 
2894   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2895   JavaCallArguments args;
2896   args.push_oop(Handle(THREAD, caller->java_mirror()));
2897   args.push_int(indy_index);
2898   args.push_oop(bsm);
2899   args.push_oop(method_name);
2900   args.push_oop(method_type);
2901   args.push_oop(info);
2902   args.push_oop(appendix_box);
2903   JavaValue result(T_OBJECT);
2904   JavaCalls::call_static(&result,
2905                          SystemDictionary::MethodHandleNatives_klass(),
2906                          vmSymbols::linkCallSite_name(),
2907                          vmSymbols::linkCallSite_signature(),
2908                          &args, CHECK_(empty));
2909   Handle mname(THREAD, (oop) result.get_jobject());
2910   (*method_type_result) = method_type;
2911   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2912 }
2913 
2914 // Protection domain cache table handling
2915 
2916 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2917   return _pd_cache_table->get(protection_domain);
2918 }
2919 
2920 #if INCLUDE_CDS
2921 void SystemDictionary::reorder_dictionary_for_sharing() {
2922   ClassLoaderData::the_null_class_loader_data()->dictionary()->reorder_dictionary_for_sharing();
2923 }
2924 #endif
2925 
2926 size_t SystemDictionary::count_bytes_for_buckets() {
2927   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_buckets();
2928 }
2929 
2930 size_t SystemDictionary::count_bytes_for_table() {
2931   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_table();
2932 }
2933 
2934 void SystemDictionary::copy_buckets(char* top, char* end) {
2935   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_buckets(top, end);
2936 }
2937 
2938 void SystemDictionary::copy_table(char* top, char* end) {
2939   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_table(top, end);
2940 }
2941 
2942 // ----------------------------------------------------------------------------
2943 void SystemDictionary::print_shared(outputStream *st) {
2944   shared_dictionary()->print_on(st);
2945 }
2946 
2947 void SystemDictionary::print_on(outputStream *st) {
2948   if (shared_dictionary() != NULL) {
2949     st->print_cr("Shared Dictionary");
2950     shared_dictionary()->print_on(st);
2951     st->cr();
2952   }
2953 
2954   GCMutexLocker mu(SystemDictionary_lock);
2955 
2956   ClassLoaderDataGraph::print_dictionary(st);
2957 
2958   // Placeholders
2959   placeholders()->print_on(st);
2960   st->cr();
2961 
2962   // loader constraints - print under SD_lock
2963   constraints()->print_on(st);
2964   st->cr();
2965 
2966   _pd_cache_table->print_on(st);
2967   st->cr();
2968 }
2969 
2970 void SystemDictionary::verify() {
2971   guarantee(constraints() != NULL,
2972             "Verify of loader constraints failed");
2973   guarantee(placeholders()->number_of_entries() >= 0,
2974             "Verify of placeholders failed");
2975 
2976   GCMutexLocker mu(SystemDictionary_lock);
2977 
2978   // Verify dictionary
2979   ClassLoaderDataGraph::verify_dictionary();
2980 
2981   placeholders()->verify();
2982 
2983   // Verify constraint table
2984   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2985   constraints()->verify(placeholders());
2986 
2987   _pd_cache_table->verify();
2988 }
2989 
2990 void SystemDictionary::dump(outputStream *st, bool verbose) {
2991   assert_locked_or_safepoint(SystemDictionary_lock);
2992   if (verbose) {
2993     print_on(st);
2994   } else {
2995     if (shared_dictionary() != NULL) {
2996       shared_dictionary()->print_table_statistics(st, "Shared Dictionary");
2997     }
2998     ClassLoaderDataGraph::print_dictionary_statistics(st);
2999     placeholders()->print_table_statistics(st, "Placeholder Table");
3000     constraints()->print_table_statistics(st, "LoaderConstraints Table");
3001     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
3002   }
3003 }
3004 
3005 // Utility for dumping dictionaries.
3006 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
3007                                  DCmdWithParser(output, heap),
3008   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
3009            "BOOLEAN", false, "false") {
3010   _dcmdparser.add_dcmd_option(&_verbose);
3011 }
3012 
3013 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
3014   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
3015                          _verbose.value());
3016   VMThread::execute(&dumper);
3017 }
3018 
3019 int SystemDictionaryDCmd::num_arguments() {
3020   ResourceMark rm;
3021   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
3022   if (dcmd != NULL) {
3023     DCmdMark mark(dcmd);
3024     return dcmd->_dcmdparser.num_arguments();
3025   } else {
3026     return 0;
3027   }
3028 }
3029 
3030 class CombineDictionariesClosure : public CLDClosure {
3031   private:
3032     Dictionary* _master_dictionary;
3033   public:
3034     CombineDictionariesClosure(Dictionary* master_dictionary) :
3035       _master_dictionary(master_dictionary) {}
3036     void do_cld(ClassLoaderData* cld) {
3037       ResourceMark rm;
3038       if (cld->is_anonymous()) {
3039         return;
3040       }
3041       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
3042         for (int i = 0; i < cld->dictionary()->table_size(); ++i) {
3043           Dictionary* curr_dictionary = cld->dictionary();
3044           DictionaryEntry* p = curr_dictionary->bucket(i);
3045           while (p != NULL) {
3046             Symbol* name = p->instance_klass()->name();
3047             unsigned int d_hash = _master_dictionary->compute_hash(name);
3048             int d_index = _master_dictionary->hash_to_index(d_hash);
3049             DictionaryEntry* next = p->next();
3050             if (p->literal()->class_loader_data() != cld) {
3051               // This is an initiating class loader entry; don't use it
3052               log_trace(cds)("Skipping initiating cl entry: %s", name->as_C_string());
3053               curr_dictionary->free_entry(p);
3054             } else {
3055               log_trace(cds)("Moved to boot dictionary: %s", name->as_C_string());
3056               curr_dictionary->unlink_entry(p);
3057               p->set_pd_set(NULL); // pd_set is runtime only information and will be reconstructed.
3058               _master_dictionary->add_entry(d_index, p);
3059             }
3060             p = next;
3061           }
3062           *curr_dictionary->bucket_addr(i) = NULL;
3063         }
3064       }
3065     }
3066 };
3067 
3068 // Combining platform and system loader dictionaries into boot loader dictionary.
3069 // During run time, we only have one shared dictionary.
3070 void SystemDictionary::combine_shared_dictionaries() {
3071   assert(DumpSharedSpaces, "dump time only");
3072   Dictionary* master_dictionary = ClassLoaderData::the_null_class_loader_data()->dictionary();
3073   CombineDictionariesClosure cdc(master_dictionary);
3074   ClassLoaderDataGraph::cld_do(&cdc);
3075 
3076   // These tables are no longer valid or necessary. Keeping them around will
3077   // cause SystemDictionary::verify() to fail. Let's empty them.
3078   _placeholders        = new PlaceholderTable(_placeholder_table_size);
3079   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
3080 
3081   NOT_PRODUCT(SystemDictionary::verify());
3082 }
3083 
3084 // caller needs ResourceMark
3085 const char* SystemDictionary::loader_name(const oop loader) {
3086   return ((loader) == NULL ? "<bootloader>" :
3087           InstanceKlass::cast((loader)->klass())->name()->as_C_string());
3088 }
3089 
3090 // caller needs ResourceMark
3091 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) {
3092   return (loader_data->class_loader() == NULL ? "<bootloader>" :
3093           SystemDictionary::loader_name(loader_data->class_loader()));
3094 }
3095 
3096 void SystemDictionary::initialize_oop_storage() {
3097   _vm_weak_oop_storage =
3098     new OopStorage("VM Weak Oop Handles",
3099                    VMWeakAlloc_lock,
3100                    VMWeakActive_lock);
3101 }
3102 
3103 OopStorage* SystemDictionary::vm_weak_oop_storage() {
3104   assert(_vm_weak_oop_storage != NULL, "Uninitialized");
3105   return _vm_weak_oop_storage;
3106 }