1 /*
   2  * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "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/gcLocker.hpp"
  47 #include "gc/shared/gcTraceTime.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/instanceKlass.hpp"
  57 #include "oops/instanceRefKlass.hpp"
  58 #include "oops/klass.inline.hpp"
  59 #include "oops/methodData.hpp"
  60 #include "oops/objArrayKlass.hpp"
  61 #include "oops/objArrayOop.inline.hpp"
  62 #include "oops/oop.inline.hpp"
  63 #include "oops/symbol.hpp"
  64 #include "oops/typeArrayKlass.hpp"
  65 #include "prims/jvmtiEnvBase.hpp"
  66 #include "prims/resolvedMethodTable.hpp"
  67 #include "prims/methodHandles.hpp"
  68 #include "runtime/arguments.hpp"
  69 #include "runtime/arguments_ext.hpp"
  70 #include "runtime/biasedLocking.hpp"
  71 #include "runtime/fieldType.hpp"
  72 #include "runtime/handles.inline.hpp"
  73 #include "runtime/java.hpp"
  74 #include "runtime/javaCalls.hpp"
  75 #include "runtime/mutexLocker.hpp"
  76 #include "runtime/orderAccess.inline.hpp"
  77 #include "runtime/signature.hpp"
  78 #include "services/classLoadingService.hpp"
  79 #include "services/diagnosticCommand.hpp"
  80 #include "services/threadService.hpp"
  81 #include "trace/tracing.hpp"
  82 #include "utilities/macros.hpp"
  83 #if INCLUDE_CDS
  84 #include "classfile/sharedClassUtil.hpp"
  85 #include "classfile/systemDictionaryShared.hpp"
  86 #endif
  87 #if INCLUDE_JVMCI
  88 #include "jvmci/jvmciRuntime.hpp"
  89 #endif
  90 
  91 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  92 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;
  93 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  94 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  95 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
  96 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
  97 
  98 int         SystemDictionary::_number_of_modifications = 0;
  99 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 100 
 101 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 102                                                           =  { NULL /*, NULL...*/ };
 103 
 104 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 105 
 106 oop         SystemDictionary::_java_system_loader         =  NULL;
 107 oop         SystemDictionary::_java_platform_loader       =  NULL;
 108 
 109 bool        SystemDictionary::_has_loadClassInternal      =  false;
 110 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 111 
 112 // lazily initialized klass variables
 113 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
 114 
 115 #if INCLUDE_VBC
 116 GrowableArray<Symbol*>* SystemDictionary::_value_based_classes    = NULL;
 117 #endif
 118 
 119 // Default ProtectionDomainCacheSize value
 120 
 121 const int defaultProtectionDomainCacheSize = 1009;
 122 
 123 
 124 // ----------------------------------------------------------------------------
 125 // Java-level SystemLoader and PlatformLoader
 126 
 127 oop SystemDictionary::java_system_loader() {
 128   return _java_system_loader;
 129 }
 130 
 131 oop SystemDictionary::java_platform_loader() {
 132   return _java_platform_loader;
 133 }
 134 
 135 void SystemDictionary::compute_java_loaders(TRAPS) {
 136   JavaValue result(T_OBJECT);
 137   InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
 138   JavaCalls::call_static(&result,
 139                          class_loader_klass,
 140                          vmSymbols::getSystemClassLoader_name(),
 141                          vmSymbols::void_classloader_signature(),
 142                          CHECK);
 143 
 144   _java_system_loader = (oop)result.get_jobject();
 145 
 146   JavaCalls::call_static(&result,
 147                          class_loader_klass,
 148                          vmSymbols::getPlatformClassLoader_name(),
 149                          vmSymbols::void_classloader_signature(),
 150                          CHECK);
 151 
 152   _java_platform_loader = (oop)result.get_jobject();
 153 
 154   CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
 155 }
 156 
 157 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
 158   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 159   return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
 160 }
 161 
 162 // ----------------------------------------------------------------------------
 163 // Parallel class loading check
 164 
 165 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 166   if (UnsyncloadClass || class_loader.is_null()) return true;
 167   if (AlwaysLockClassLoader) return false;
 168   return java_lang_ClassLoader::parallelCapable(class_loader());
 169 }
 170 // ----------------------------------------------------------------------------
 171 // ParallelDefineClass flag does not apply to bootclass loader
 172 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 173    if (class_loader.is_null()) return false;
 174    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 175      return true;
 176    }
 177    return false;
 178 }
 179 
 180 // Returns true if the passed class loader is the builtin application class loader
 181 // or a custom system class loader. A customer system class loader can be
 182 // specified via -Djava.system.class.loader.
 183 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 184   if (class_loader == NULL) {
 185     return false;
 186   }
 187   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 188        class_loader == _java_system_loader);
 189 }
 190 
 191 // Returns true if the passed class loader is the platform class loader.
 192 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 193   if (class_loader == NULL) {
 194     return false;
 195   }
 196   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 197 }
 198 
 199 // ----------------------------------------------------------------------------
 200 // Resolving of classes
 201 
 202 // Forwards to resolve_or_null
 203 
 204 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 205   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 206   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 207     // can return a null klass
 208     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 209   }
 210   return klass;
 211 }
 212 
 213 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 214                                                      bool throw_error,
 215                                                      Klass* klass, TRAPS) {
 216   if (HAS_PENDING_EXCEPTION) {
 217     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 218     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 219     // and if so convert it to a NoClassDefFoundError
 220     // And chain the original ClassNotFoundException
 221     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 222       ResourceMark rm(THREAD);
 223       assert(klass == NULL, "Should not have result with exception pending");
 224       Handle e(THREAD, PENDING_EXCEPTION);
 225       CLEAR_PENDING_EXCEPTION;
 226       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 227     } else {
 228       return NULL;
 229     }
 230   }
 231   // Class not found, throw appropriate error or exception depending on value of throw_error
 232   if (klass == NULL) {
 233     ResourceMark rm(THREAD);
 234     if (throw_error) {
 235       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 236     } else {
 237       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 238     }
 239   }
 240   return klass;
 241 }
 242 
 243 
 244 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 245                                            bool throw_error, TRAPS)
 246 {
 247   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 248 }
 249 
 250 
 251 // Forwards to resolve_instance_class_or_null
 252 
 253 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 254   assert(THREAD->can_call_java(),
 255          "can not load classes with compiler thread: class=%s, classloader=%s",
 256          class_name->as_C_string(),
 257          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 258   if (FieldType::is_array(class_name)) {
 259     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 260   } else if (FieldType::is_obj(class_name)) {
 261     ResourceMark rm(THREAD);
 262     // Ignore wrapping L and ;.
 263     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 264                                    class_name->utf8_length() - 2, CHECK_NULL);
 265     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 266   } else {
 267     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 268   }
 269 }
 270 
 271 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 272   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 273 }
 274 
 275 // Forwards to resolve_instance_class_or_null
 276 
 277 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 278                                                      Handle class_loader,
 279                                                      Handle protection_domain,
 280                                                      TRAPS) {
 281   assert(FieldType::is_array(class_name), "must be array");
 282   Klass* k = NULL;
 283   FieldArrayInfo fd;
 284   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 285   // of this call
 286   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 287   if (t == T_OBJECT) {
 288     // naked oop "k" is OK here -- we assign back into it
 289     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 290                                                          class_loader,
 291                                                          protection_domain,
 292                                                          CHECK_NULL);
 293     if (k != NULL) {
 294       k = k->array_klass(fd.dimension(), CHECK_NULL);
 295     }
 296   } else {
 297     k = Universe::typeArrayKlassObj(t);
 298     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 299   }
 300   return k;
 301 }
 302 
 303 
 304 // Must be called for any super-class or super-interface resolution
 305 // during class definition to allow class circularity checking
 306 // super-interface callers:
 307 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 308 // super-class callers:
 309 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 310 //   load_shared_class - while loading a class from shared archive
 311 //   resolve_instance_class_or_null:
 312 //     via: handle_parallel_super_load
 313 //      when resolving a class that has an existing placeholder with
 314 //      a saved superclass [i.e. a defineClass is currently in progress]
 315 //      if another thread is trying to resolve the class, it must do
 316 //      super-class checks on its own thread to catch class circularity
 317 // This last call is critical in class circularity checking for cases
 318 // where classloading is delegated to different threads and the
 319 // classloader lock is released.
 320 // Take the case: Base->Super->Base
 321 //   1. If thread T1 tries to do a defineClass of class Base
 322 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 323 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 324 //    so it tries to load Super
 325 //   3. If we load the class internally, or user classloader uses same thread
 326 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 327 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 328 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 329 //      3.4 calls resolve_super_or_fail Base
 330 //      3.5 finds T1,Base -> throws class circularity
 331 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 332 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 333 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 334 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 335 //      4.4 finds T2, Super -> throws class circularity
 336 // Must be called, even if superclass is null, since this is
 337 // where the placeholder entry is created which claims this
 338 // thread is loading this class/classloader.
 339 // Be careful when modifying this code: once you have run
 340 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 341 // you need to find_and_remove it before returning.
 342 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 343 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 344                                                  Symbol* class_name,
 345                                                  Handle class_loader,
 346                                                  Handle protection_domain,
 347                                                  bool is_superclass,
 348                                                  TRAPS) {
 349 #if INCLUDE_CDS
 350   if (DumpSharedSpaces) {
 351     // Special processing for CDS dump time.
 352     Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 353         class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 354     if (k) {
 355       return k;
 356     }
 357   }
 358 #endif // INCLUDE_CDS
 359 
 360   // Double-check, if child class is already loaded, just return super-class,interface
 361   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 362   // dictionary.
 363   // Make sure there's a placeholder for the *child* before resolving.
 364   // Used as a claim that this thread is currently loading superclass/classloader
 365   // Used here for ClassCircularity checks and also for heap verification
 366   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 367   // Must check ClassCircularity before checking if super class is already loaded.
 368   //
 369   // We might not already have a placeholder if this child_name was
 370   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 371   // the name of the class might not be known until the stream is actually
 372   // parsed.
 373   // Bugs 4643874, 4715493
 374 
 375   ClassLoaderData* loader_data = class_loader_data(class_loader);
 376   Dictionary* dictionary = loader_data->dictionary();
 377   unsigned int d_hash = dictionary->compute_hash(child_name);
 378   unsigned int p_hash = placeholders()->compute_hash(child_name);
 379   int p_index = placeholders()->hash_to_index(p_hash);
 380   // can't throw error holding a lock
 381   bool child_already_loaded = false;
 382   bool throw_circularity_error = false;
 383   {
 384     MutexLocker mu(SystemDictionary_lock, THREAD);
 385     Klass* childk = find_class(d_hash, child_name, dictionary);
 386     Klass* quicksuperk;
 387     // to support // loading: if child done loading, just return superclass
 388     // if class_name, & class_loader don't match:
 389     // if initial define, SD update will give LinkageError
 390     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 391     // so we don't throw an exception here.
 392     // see: nsk redefclass014 & java.lang.instrument Instrument032
 393     if ((childk != NULL ) && (is_superclass) &&
 394        ((quicksuperk = childk->super()) != NULL) &&
 395 
 396          ((quicksuperk->name() == class_name) &&
 397             (quicksuperk->class_loader()  == class_loader()))) {
 398            return quicksuperk;
 399     } else {
 400       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 401       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 402           throw_circularity_error = true;
 403       }
 404     }
 405     if (!throw_circularity_error) {
 406       // Be careful not to exit resolve_super
 407       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 408     }
 409   }
 410   if (throw_circularity_error) {
 411       ResourceMark rm(THREAD);
 412       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 413   }
 414 
 415 // java.lang.Object should have been found above
 416   assert(class_name != NULL, "null super class for resolving");
 417   // Resolve the super class or interface, check results on return
 418   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 419                                                     class_loader,
 420                                                     protection_domain,
 421                                                     THREAD);
 422 
 423   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 424   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 425   // or error. GC used to walk the placeholder table as strong roots.
 426   // The instanceKlass is kept alive because the class loader is on the stack,
 427   // which keeps the loader_data alive, as well as all instanceKlasses in
 428   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 429   {
 430     MutexLocker mu(SystemDictionary_lock, THREAD);
 431     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 432     SystemDictionary_lock->notify_all();
 433   }
 434   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 435     // can null superk
 436     superk = handle_resolution_exception(class_name, true, superk, THREAD);
 437   }
 438 
 439   return superk;
 440 }
 441 
 442 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 443                                                   Handle class_loader,
 444                                                   Handle protection_domain,
 445                                                   TRAPS) {
 446   if(!has_checkPackageAccess()) return;
 447 
 448   // Now we have to call back to java to check if the initating class has access
 449   JavaValue result(T_VOID);
 450   LogTarget(Debug, protectiondomain) lt;
 451   if (lt.is_enabled()) {
 452     ResourceMark rm;
 453     // Print out trace information
 454     LogStream ls(lt);
 455     ls.print_cr("Checking package access");
 456     ls.print("class loader: "); class_loader()->print_value_on(&ls);
 457     ls.print(" protection domain: "); protection_domain()->print_value_on(&ls);
 458     ls.print(" loading: "); klass->print_value_on(&ls);
 459     ls.cr();
 460   }
 461 
 462   // This handle and the class_loader handle passed in keeps this class from
 463   // being unloaded through several GC points.
 464   // The class_loader handle passed in is the initiating loader.
 465   Handle mirror(THREAD, klass->java_mirror());
 466 
 467   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 468   JavaCalls::call_special(&result,
 469                          class_loader,
 470                          system_loader,
 471                          vmSymbols::checkPackageAccess_name(),
 472                          vmSymbols::class_protectiondomain_signature(),
 473                          mirror,
 474                          protection_domain,
 475                          THREAD);
 476 
 477   if (HAS_PENDING_EXCEPTION) {
 478     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 479   } else {
 480    log_debug(protectiondomain)("granted");
 481   }
 482 
 483   if (HAS_PENDING_EXCEPTION) return;
 484 
 485   // If no exception has been thrown, we have validated the protection domain
 486   // Insert the protection domain of the initiating class into the set.
 487   {
 488     ClassLoaderData* loader_data = class_loader_data(class_loader);
 489     Dictionary* dictionary = loader_data->dictionary();
 490 
 491     Symbol*  kn = klass->name();
 492     unsigned int d_hash = dictionary->compute_hash(kn);
 493 
 494     MutexLocker mu(SystemDictionary_lock, THREAD);
 495     int d_index = dictionary->hash_to_index(d_hash);
 496     dictionary->add_protection_domain(d_index, d_hash, klass,
 497                                       protection_domain, THREAD);
 498   }
 499 }
 500 
 501 // We only get here if this thread finds that another thread
 502 // has already claimed the placeholder token for the current operation,
 503 // but that other thread either never owned or gave up the
 504 // object lock
 505 // Waits on SystemDictionary_lock to indicate placeholder table updated
 506 // On return, caller must recheck placeholder table state
 507 //
 508 // We only get here if
 509 //  1) custom classLoader, i.e. not bootstrap classloader
 510 //  2) UnsyncloadClass not set
 511 //  3) custom classLoader has broken the class loader objectLock
 512 //     so another thread got here in parallel
 513 //
 514 // lockObject must be held.
 515 // Complicated dance due to lock ordering:
 516 // Must first release the classloader object lock to
 517 // allow initial definer to complete the class definition
 518 // and to avoid deadlock
 519 // Reclaim classloader lock object with same original recursion count
 520 // Must release SystemDictionary_lock after notify, since
 521 // class loader lock must be claimed before SystemDictionary_lock
 522 // to prevent deadlocks
 523 //
 524 // The notify allows applications that did an untimed wait() on
 525 // the classloader object lock to not hang.
 526 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 527   assert_lock_strong(SystemDictionary_lock);
 528 
 529   bool calledholdinglock
 530       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 531   assert(calledholdinglock,"must hold lock for notify");
 532   assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 533   ObjectSynchronizer::notifyall(lockObject, THREAD);
 534   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 535   SystemDictionary_lock->wait();
 536   SystemDictionary_lock->unlock();
 537   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 538   SystemDictionary_lock->lock();
 539 }
 540 
 541 // If the class in is in the placeholder table, class loading is in progress
 542 // For cases where the application changes threads to load classes, it
 543 // is critical to ClassCircularity detection that we try loading
 544 // the superclass on the same thread internally, so we do parallel
 545 // super class loading here.
 546 // This also is critical in cases where the original thread gets stalled
 547 // even in non-circularity situations.
 548 // Note: must call resolve_super_or_fail even if null super -
 549 // to force placeholder entry creation for this class for circularity detection
 550 // Caller must check for pending exception
 551 // Returns non-null Klass* if other thread has completed load
 552 // and we are done,
 553 // If return null Klass* and no pending exception, the caller must load the class
 554 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 555     Symbol* name, Symbol* superclassname, Handle class_loader,
 556     Handle protection_domain, Handle lockObject, TRAPS) {
 557 
 558   ClassLoaderData* loader_data = class_loader_data(class_loader);
 559   Dictionary* dictionary = loader_data->dictionary();
 560   unsigned int d_hash = dictionary->compute_hash(name);
 561   unsigned int p_hash = placeholders()->compute_hash(name);
 562   int p_index = placeholders()->hash_to_index(p_hash);
 563 
 564   // superk is not used, resolve_super called for circularity check only
 565   // This code is reached in two situations. One if this thread
 566   // is loading the same class twice (e.g. ClassCircularity, or
 567   // java.lang.instrument).
 568   // The second is if another thread started the resolve_super first
 569   // and has not yet finished.
 570   // In both cases the original caller will clean up the placeholder
 571   // entry on error.
 572   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 573                                                           superclassname,
 574                                                           class_loader,
 575                                                           protection_domain,
 576                                                           true,
 577                                                           CHECK_NULL);
 578 
 579   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 580   // Serial class loaders and bootstrap classloader do wait for superclass loads
 581  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 582     MutexLocker mu(SystemDictionary_lock, THREAD);
 583     // Check if classloading completed while we were loading superclass or waiting
 584     return find_class(d_hash, name, dictionary);
 585   }
 586 
 587   // must loop to both handle other placeholder updates
 588   // and spurious notifications
 589   bool super_load_in_progress = true;
 590   PlaceholderEntry* placeholder;
 591   while (super_load_in_progress) {
 592     MutexLocker mu(SystemDictionary_lock, THREAD);
 593     // Check if classloading completed while we were loading superclass or waiting
 594     InstanceKlass* check = find_class(d_hash, name, dictionary);
 595     if (check != NULL) {
 596       // Klass is already loaded, so just return it
 597       return check;
 598     } else {
 599       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 600       if (placeholder && placeholder->super_load_in_progress() ){
 601         // Before UnsyncloadClass:
 602         // We only get here if the application has released the
 603         // classloader lock when another thread was in the middle of loading a
 604         // superclass/superinterface for this class, and now
 605         // this thread is also trying to load this class.
 606         // To minimize surprises, the first thread that started to
 607         // load a class should be the one to complete the loading
 608         // with the classfile it initially expected.
 609         // This logic has the current thread wait once it has done
 610         // all the superclass/superinterface loading it can, until
 611         // the original thread completes the class loading or fails
 612         // If it completes we will use the resulting InstanceKlass
 613         // which we will find below in the systemDictionary.
 614         // We also get here for parallel bootstrap classloader
 615         if (class_loader.is_null()) {
 616           SystemDictionary_lock->wait();
 617         } else {
 618           double_lock_wait(lockObject, THREAD);
 619         }
 620       } else {
 621         // If not in SD and not in PH, other thread's load must have failed
 622         super_load_in_progress = false;
 623       }
 624     }
 625   }
 626   return NULL;
 627 }
 628 
 629 static void post_class_load_event(EventClassLoad* event,
 630                                   const InstanceKlass* k,
 631                                   const ClassLoaderData* init_cld) {
 632 #if INCLUDE_TRACE
 633   assert(event != NULL, "invariant");
 634   assert(k != NULL, "invariant");
 635   if (event->should_commit()) {
 636     event->set_loadedClass(k);
 637     event->set_definingClassLoader(k->class_loader_data());
 638     event->set_initiatingClassLoader(init_cld);
 639     event->commit();
 640   }
 641 #endif // INCLUDE_TRACE
 642 }
 643 
 644 static void class_define_event(InstanceKlass* k,
 645                                const ClassLoaderData* def_cld) {
 646 #if INCLUDE_TRACE
 647   EventClassDefine event;
 648   if (event.should_commit()) {
 649     event.set_definedClass(k);
 650     event.set_definingClassLoader(def_cld);
 651     event.commit();
 652   }
 653 #endif // INCLUDE_TRACE
 654 }
 655 
 656 // Be careful when modifying this code: once you have run
 657 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 658 // you need to find_and_remove it before returning.
 659 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 660 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 661                                                         Handle class_loader,
 662                                                         Handle protection_domain,
 663                                                         TRAPS) {
 664   assert(name != NULL && !FieldType::is_array(name) &&
 665          !FieldType::is_obj(name), "invalid class name");
 666 
 667   EventClassLoad class_load_start_event;
 668 
 669   HandleMark hm(THREAD);
 670 
 671   // Fix for 4474172; see evaluation for more details
 672   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 673   ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
 674   Dictionary* dictionary = loader_data->dictionary();
 675   unsigned int d_hash = dictionary->compute_hash(name);
 676 
 677   // Do lookup to see if class already exist and the protection domain
 678   // has the right access
 679   // This call uses find which checks protection domain already matches
 680   // All subsequent calls use find_class, and set has_loaded_class so that
 681   // before we return a result we call out to java to check for valid protection domain
 682   // to allow returning the Klass* and add it to the pd_set if it is valid
 683   {
 684     Klass* probe = dictionary->find(d_hash, name, protection_domain);
 685     if (probe != NULL) return probe;
 686   }
 687 
 688   // Non-bootstrap class loaders will call out to class loader and
 689   // define via jvm/jni_DefineClass which will acquire the
 690   // class loader object lock to protect against multiple threads
 691   // defining the class in parallel by accident.
 692   // This lock must be acquired here so the waiter will find
 693   // any successful result in the SystemDictionary and not attempt
 694   // the define
 695   // ParallelCapable Classloaders and the bootstrap classloader,
 696   // or all classloaders with UnsyncloadClass do not acquire lock here
 697   bool DoObjectLock = true;
 698   if (is_parallelCapable(class_loader)) {
 699     DoObjectLock = false;
 700   }
 701 
 702   unsigned int p_hash = placeholders()->compute_hash(name);
 703   int p_index = placeholders()->hash_to_index(p_hash);
 704 
 705   // Class is not in SystemDictionary so we have to do loading.
 706   // Make sure we are synchronized on the class loader before we proceed
 707   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 708   check_loader_lock_contention(lockObject, THREAD);
 709   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 710 
 711   // Check again (after locking) if class already exist in SystemDictionary
 712   bool class_has_been_loaded   = false;
 713   bool super_load_in_progress  = false;
 714   bool havesupername = false;
 715   InstanceKlass* k = NULL;
 716   PlaceholderEntry* placeholder;
 717   Symbol* superclassname = NULL;
 718 
 719   {
 720     MutexLocker mu(SystemDictionary_lock, THREAD);
 721     InstanceKlass* check = find_class(d_hash, name, dictionary);
 722     if (check != NULL) {
 723       // Klass is already loaded, so just return it
 724       class_has_been_loaded = true;
 725       k = check;
 726     } else {
 727       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 728       if (placeholder && placeholder->super_load_in_progress()) {
 729          super_load_in_progress = true;
 730          if (placeholder->havesupername() == true) {
 731            superclassname = placeholder->supername();
 732            havesupername = true;
 733          }
 734       }
 735     }
 736   }
 737 
 738   // If the class is in the placeholder table, class loading is in progress
 739   if (super_load_in_progress && havesupername==true) {
 740     k = handle_parallel_super_load(name,
 741                                    superclassname,
 742                                    class_loader,
 743                                    protection_domain,
 744                                    lockObject, THREAD);
 745     if (HAS_PENDING_EXCEPTION) {
 746       return NULL;
 747     }
 748     if (k != NULL) {
 749       class_has_been_loaded = true;
 750     }
 751   }
 752 
 753   bool throw_circularity_error = false;
 754   if (!class_has_been_loaded) {
 755     bool load_instance_added = false;
 756 
 757     // add placeholder entry to record loading instance class
 758     // Five cases:
 759     // All cases need to prevent modifying bootclasssearchpath
 760     // in parallel with a classload of same classname
 761     // Redefineclasses uses existence of the placeholder for the duration
 762     // of the class load to prevent concurrent redefinition of not completely
 763     // defined classes.
 764     // case 1. traditional classloaders that rely on the classloader object lock
 765     //   - no other need for LOAD_INSTANCE
 766     // case 2. traditional classloaders that break the classloader object lock
 767     //    as a deadlock workaround. Detection of this case requires that
 768     //    this check is done while holding the classloader object lock,
 769     //    and that lock is still held when calling classloader's loadClass.
 770     //    For these classloaders, we ensure that the first requestor
 771     //    completes the load and other requestors wait for completion.
 772     // case 3. UnsyncloadClass - don't use objectLocker
 773     //    With this flag, we allow parallel classloading of a
 774     //    class/classloader pair
 775     // case4. Bootstrap classloader - don't own objectLocker
 776     //    This classloader supports parallelism at the classloader level,
 777     //    but only allows a single load of a class/classloader pair.
 778     //    No performance benefit and no deadlock issues.
 779     // case 5. parallelCapable user level classloaders - without objectLocker
 780     //    Allow parallel classloading of a class/classloader pair
 781 
 782     {
 783       MutexLocker mu(SystemDictionary_lock, THREAD);
 784       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 785         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 786         if (oldprobe) {
 787           // only need check_seen_thread once, not on each loop
 788           // 6341374 java/lang/Instrument with -Xcomp
 789           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 790             throw_circularity_error = true;
 791           } else {
 792             // case 1: traditional: should never see load_in_progress.
 793             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 794 
 795               // case 4: bootstrap classloader: prevent futile classloading,
 796               // wait on first requestor
 797               if (class_loader.is_null()) {
 798                 SystemDictionary_lock->wait();
 799               } else {
 800               // case 2: traditional with broken classloader lock. wait on first
 801               // requestor.
 802                 double_lock_wait(lockObject, THREAD);
 803               }
 804               // Check if classloading completed while we were waiting
 805               InstanceKlass* check = find_class(d_hash, name, dictionary);
 806               if (check != NULL) {
 807                 // Klass is already loaded, so just return it
 808                 k = check;
 809                 class_has_been_loaded = true;
 810               }
 811               // check if other thread failed to load and cleaned up
 812               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 813             }
 814           }
 815         }
 816       }
 817       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 818       // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
 819       // LOAD_INSTANCE in parallel
 820 
 821       if (!throw_circularity_error && !class_has_been_loaded) {
 822         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 823         load_instance_added = true;
 824         // For class loaders that do not acquire the classloader object lock,
 825         // if they did not catch another thread holding LOAD_INSTANCE,
 826         // need a check analogous to the acquire ObjectLocker/find_class
 827         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 828         // one final check if the load has already completed
 829         // class loaders holding the ObjectLock shouldn't find the class here
 830         InstanceKlass* check = find_class(d_hash, name, dictionary);
 831         if (check != NULL) {
 832         // Klass is already loaded, so return it after checking/adding protection domain
 833           k = check;
 834           class_has_been_loaded = true;
 835         }
 836       }
 837     }
 838 
 839     // must throw error outside of owning lock
 840     if (throw_circularity_error) {
 841       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 842       ResourceMark rm(THREAD);
 843       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 844     }
 845 
 846     if (!class_has_been_loaded) {
 847 
 848       // Do actual loading
 849       k = load_instance_class(name, class_loader, THREAD);
 850 
 851       // For UnsyncloadClass only
 852       // If they got a linkageError, check if a parallel class load succeeded.
 853       // If it did, then for bytecode resolution the specification requires
 854       // that we return the same result we did for the other thread, i.e. the
 855       // successfully loaded InstanceKlass
 856       // Should not get here for classloaders that support parallelism
 857       // with the new cleaner mechanism, even with AllowParallelDefineClass
 858       // Bootstrap goes through here to allow for an extra guarantee check
 859       if (UnsyncloadClass || (class_loader.is_null())) {
 860         if (k == NULL && HAS_PENDING_EXCEPTION
 861           && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
 862           MutexLocker mu(SystemDictionary_lock, THREAD);
 863           InstanceKlass* check = find_class(d_hash, name, dictionary);
 864           if (check != NULL) {
 865             // Klass is already loaded, so just use it
 866             k = check;
 867             CLEAR_PENDING_EXCEPTION;
 868             guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
 869           }
 870         }
 871       }
 872 
 873       // If everything was OK (no exceptions, no null return value), and
 874       // class_loader is NOT the defining loader, do a little more bookkeeping.
 875       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 876         k->class_loader() != class_loader()) {
 877 
 878         check_constraints(d_hash, k, class_loader, false, THREAD);
 879 
 880         // Need to check for a PENDING_EXCEPTION again; check_constraints
 881         // can throw and doesn't use the CHECK macro.
 882         if (!HAS_PENDING_EXCEPTION) {
 883           { // Grabbing the Compile_lock prevents systemDictionary updates
 884             // during compilations.
 885             MutexLocker mu(Compile_lock, THREAD);
 886             update_dictionary(d_hash, p_index, p_hash,
 887               k, class_loader, THREAD);
 888           }
 889 
 890           if (JvmtiExport::should_post_class_load()) {
 891             Thread *thread = THREAD;
 892             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 893             JvmtiExport::post_class_load((JavaThread *) thread, k);
 894           }
 895         }
 896       }
 897     } // load_instance_class
 898 
 899     if (load_instance_added == true) {
 900       // clean up placeholder entries for LOAD_INSTANCE success or error
 901       // This brackets the SystemDictionary updates for both defining
 902       // and initiating loaders
 903       MutexLocker mu(SystemDictionary_lock, THREAD);
 904       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 905       SystemDictionary_lock->notify_all();
 906     }
 907   }
 908 
 909   if (HAS_PENDING_EXCEPTION || k == NULL) {
 910     return NULL;
 911   }
 912 
 913   post_class_load_event(&class_load_start_event, k, loader_data);
 914 
 915 #ifdef ASSERT
 916   {
 917     ClassLoaderData* loader_data = k->class_loader_data();
 918     MutexLocker mu(SystemDictionary_lock, THREAD);
 919     Klass* kk = find_class(name, loader_data);
 920     assert(kk == k, "should be present in dictionary");
 921   }
 922 #endif
 923 
 924   // return if the protection domain in NULL
 925   if (protection_domain() == NULL) return k;
 926 
 927   // Check the protection domain has the right access
 928   if (dictionary->is_valid_protection_domain(d_hash, name,
 929                                              protection_domain)) {
 930     return k;
 931   }
 932 
 933   // Verify protection domain. If it fails an exception is thrown
 934   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 935 
 936   return k;
 937 }
 938 
 939 
 940 // This routine does not lock the system dictionary.
 941 //
 942 // Since readers don't hold a lock, we must make sure that system
 943 // dictionary entries are only removed at a safepoint (when only one
 944 // thread is running), and are added to in a safe way (all links must
 945 // be updated in an MT-safe manner).
 946 //
 947 // Callers should be aware that an entry could be added just after
 948 // _dictionary->bucket(index) is read here, so the caller will not see
 949 // the new entry.
 950 
 951 Klass* SystemDictionary::find(Symbol* class_name,
 952                               Handle class_loader,
 953                               Handle protection_domain,
 954                               TRAPS) {
 955 
 956   // The result of this call should be consistent with the result
 957   // of the call to resolve_instance_class_or_null().
 958   // See evaluation 6790209 and 4474172 for more details.
 959   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 960   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 961 
 962   if (loader_data == NULL) {
 963     // If the ClassLoaderData has not been setup,
 964     // then the class loader has no entries in the dictionary.
 965     return NULL;
 966   }
 967 
 968   Dictionary* dictionary = loader_data->dictionary();
 969   unsigned int d_hash = dictionary->compute_hash(class_name);
 970   return dictionary->find(d_hash, class_name,
 971                           protection_domain);
 972 }
 973 
 974 
 975 // Look for a loaded instance or array klass by name.  Do not do any loading.
 976 // return NULL in case of error.
 977 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 978                                                       Handle class_loader,
 979                                                       Handle protection_domain,
 980                                                       TRAPS) {
 981   Klass* k = NULL;
 982   assert(class_name != NULL, "class name must be non NULL");
 983 
 984   if (FieldType::is_array(class_name)) {
 985     // The name refers to an array.  Parse the name.
 986     // dimension and object_key in FieldArrayInfo are assigned as a
 987     // side-effect of this call
 988     FieldArrayInfo fd;
 989     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 990     if (t != T_OBJECT) {
 991       k = Universe::typeArrayKlassObj(t);
 992     } else {
 993       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 994     }
 995     if (k != NULL) {
 996       k = k->array_klass_or_null(fd.dimension());
 997     }
 998   } else {
 999     k = find(class_name, class_loader, protection_domain, THREAD);
1000   }
1001   return k;
1002 }
1003 
1004 // Note: this method is much like resolve_from_stream, but
1005 // does not publish the classes via the SystemDictionary.
1006 // Handles unsafe_DefineAnonymousClass and redefineclasses
1007 // RedefinedClasses do not add to the class hierarchy
1008 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
1009                                               Handle class_loader,
1010                                               Handle protection_domain,
1011                                               ClassFileStream* st,
1012                                               const InstanceKlass* host_klass,
1013                                               GrowableArray<Handle>* cp_patches,
1014                                               TRAPS) {
1015 
1016   EventClassLoad class_load_start_event;
1017 
1018   ClassLoaderData* loader_data;
1019   if (host_klass != NULL) {
1020     // Create a new CLD for anonymous class, that uses the same class loader
1021     // as the host_klass
1022     guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1023     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1024   } else {
1025     loader_data = ClassLoaderData::class_loader_data(class_loader());
1026   }
1027 
1028   assert(st != NULL, "invariant");
1029   assert(st->need_verify(), "invariant");
1030 
1031   // Parse stream and create a klass.
1032   // Note that we do this even though this klass might
1033   // already be present in the SystemDictionary, otherwise we would not
1034   // throw potential ClassFormatErrors.
1035 
1036   InstanceKlass* k = KlassFactory::create_from_stream(st,
1037                                                       class_name,
1038                                                       loader_data,
1039                                                       protection_domain,
1040                                                       host_klass,
1041                                                       cp_patches,
1042                                                       CHECK_NULL);
1043 
1044   if (host_klass != NULL && k != NULL) {
1045     // If it's anonymous, initialize it now, since nobody else will.
1046 
1047     {
1048       MutexLocker mu_r(Compile_lock, THREAD);
1049 
1050       // Add to class hierarchy, initialize vtables, and do possible
1051       // deoptimizations.
1052       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1053 
1054       // But, do not add to dictionary.
1055 
1056       // compiled code dependencies need to be validated anyway
1057       notice_modification();
1058     }
1059 
1060     // Rewrite and patch constant pool here.
1061     k->link_class(CHECK_NULL);
1062     if (cp_patches != NULL) {
1063       k->constants()->patch_resolved_references(cp_patches);
1064     }
1065     k->eager_initialize(CHECK_NULL);
1066 
1067     // notify jvmti
1068     if (JvmtiExport::should_post_class_load()) {
1069         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1070         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1071     }
1072 
1073     post_class_load_event(&class_load_start_event, k, loader_data);
1074   }
1075   assert(host_klass != NULL || NULL == cp_patches,
1076          "cp_patches only found with host_klass");
1077 
1078   return k;
1079 }
1080 
1081 // Add a klass to the system from a stream (called by jni_DefineClass and
1082 // JVM_DefineClass).
1083 // Note: class_name can be NULL. In that case we do not know the name of
1084 // the class until we have parsed the stream.
1085 
1086 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1087                                                      Handle class_loader,
1088                                                      Handle protection_domain,
1089                                                      ClassFileStream* st,
1090                                                      TRAPS) {
1091 #if INCLUDE_CDS
1092   ResourceMark rm(THREAD);
1093   if (DumpSharedSpaces && !class_loader.is_null() &&
1094       !UseAppCDS && strcmp(class_name->as_C_string(), "Unnamed") != 0) {
1095     // If AppCDS is not enabled, don't define the class at dump time (except for the "Unnamed"
1096     // class, which is used by MethodHandles).
1097     THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
1098   }
1099 #endif
1100 
1101   HandleMark hm(THREAD);
1102 
1103   // Classloaders that support parallelism, e.g. bootstrap classloader,
1104   // or all classloaders with UnsyncloadClass do not acquire lock here
1105   bool DoObjectLock = true;
1106   if (is_parallelCapable(class_loader)) {
1107     DoObjectLock = false;
1108   }
1109 
1110   ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1111 
1112   // Make sure we are synchronized on the class loader before we proceed
1113   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1114   check_loader_lock_contention(lockObject, THREAD);
1115   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1116 
1117   assert(st != NULL, "invariant");
1118 
1119   // Parse the stream and create a klass.
1120   // Note that we do this even though this klass might
1121   // already be present in the SystemDictionary, otherwise we would not
1122   // throw potential ClassFormatErrors.
1123  InstanceKlass* k = NULL;
1124 
1125 #if INCLUDE_CDS
1126   if (!DumpSharedSpaces) {
1127     k = SystemDictionaryShared::lookup_from_stream(class_name,
1128                                                    class_loader,
1129                                                    protection_domain,
1130                                                    st,
1131                                                    CHECK_NULL);
1132   }
1133 #endif
1134 
1135   if (k == NULL) {
1136     if (st->buffer() == NULL) {
1137       return NULL;
1138     }
1139     k = KlassFactory::create_from_stream(st,
1140                                          class_name,
1141                                          loader_data,
1142                                          protection_domain,
1143                                          NULL, // host_klass
1144                                          NULL, // cp_patches
1145                                          CHECK_NULL);
1146   }
1147 
1148   assert(k != NULL, "no klass created");
1149   Symbol* h_name = k->name();
1150   assert(class_name == NULL || class_name == h_name, "name mismatch");
1151 
1152   // Add class just loaded
1153   // If a class loader supports parallel classloading handle parallel define requests
1154   // find_or_define_instance_class may return a different InstanceKlass
1155   if (is_parallelCapable(class_loader)) {
1156     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1157     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1158       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1159       assert(defined_k != NULL, "Should have a klass if there's no exception");
1160       loader_data->add_to_deallocate_list(k);
1161       k = defined_k;
1162     }
1163   } else {
1164     define_instance_class(k, THREAD);
1165   }
1166 
1167   // If defining the class throws an exception register 'k' for cleanup.
1168   if (HAS_PENDING_EXCEPTION) {
1169     assert(k != NULL, "Must have an instance klass here!");
1170     loader_data->add_to_deallocate_list(k);
1171     return NULL;
1172   }
1173 
1174   // Make sure we have an entry in the SystemDictionary on success
1175   debug_only( {
1176     MutexLocker mu(SystemDictionary_lock, THREAD);
1177 
1178     Klass* check = find_class(h_name, k->class_loader_data());
1179     assert(check == k, "should be present in the dictionary");
1180   } );
1181 
1182   return k;
1183 }
1184 
1185 #if INCLUDE_CDS
1186 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1187                                              int number_of_entries) {
1188   assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>),
1189          "bad shared dictionary size.");
1190   _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(),
1191                                       _shared_dictionary_size, t, number_of_entries);
1192 }
1193 
1194 
1195 // If there is a shared dictionary, then find the entry for the
1196 // given shared system class, if any.
1197 
1198 InstanceKlass* SystemDictionary::find_shared_class(Symbol* class_name) {
1199   if (shared_dictionary() != NULL) {
1200     unsigned int d_hash = shared_dictionary()->compute_hash(class_name);
1201     int d_index = shared_dictionary()->hash_to_index(d_hash);
1202 
1203     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1204   } else {
1205     return NULL;
1206   }
1207 }
1208 
1209 
1210 // Load a class from the shared spaces (found through the shared system
1211 // dictionary).  Force the superclass and all interfaces to be loaded.
1212 // Update the class definition to include sibling classes and no
1213 // subclasses (yet).  [Classes in the shared space are not part of the
1214 // object hierarchy until loaded.]
1215 
1216 InstanceKlass* SystemDictionary::load_shared_class(
1217                  Symbol* class_name, Handle class_loader, TRAPS) {
1218   InstanceKlass* ik = find_shared_class(class_name);
1219   // Make sure we only return the boot class for the NULL classloader.
1220   if (ik != NULL &&
1221       ik->is_shared_boot_class() && class_loader.is_null()) {
1222     Handle protection_domain;
1223     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1224   }
1225   return NULL;
1226 }
1227 
1228 // Check if a shared class can be loaded by the specific classloader:
1229 //
1230 // NULL classloader:
1231 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1232 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1233 //     be defined in an unnamed module.
1234 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1235                                                InstanceKlass* ik,
1236                                                Handle class_loader, TRAPS) {
1237   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1238          "Cannot use sharing if java.base is patched");
1239   ResourceMark rm;
1240   int path_index = ik->shared_classpath_index();
1241   ClassLoaderData* loader_data = class_loader_data(class_loader);
1242   if (path_index < 0) {
1243     // path_index < 0 indicates that the class is intended for a custom loader
1244     // and should not be loaded by boot/platform/app loaders
1245     if (loader_data->is_builtin_class_loader_data()) {
1246       return false;
1247     } else {
1248       return true;
1249     }
1250   }
1251   SharedClassPathEntry* ent =
1252             (SharedClassPathEntry*)FileMapInfo::shared_classpath(path_index);
1253   if (!Universe::is_module_initialized()) {
1254     assert(ent != NULL && ent->is_modules_image(),
1255            "Loading non-bootstrap classes before the module system is initialized");
1256     assert(class_loader.is_null(), "sanity");
1257     return true;
1258   }
1259   // Get the pkg_entry from the classloader
1260   TempNewSymbol pkg_name = NULL;
1261   PackageEntry* pkg_entry = NULL;
1262   ModuleEntry* mod_entry = NULL;
1263   const char* pkg_string = NULL;
1264   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1265   if (pkg_name != NULL) {
1266     pkg_string = pkg_name->as_C_string();
1267     if (loader_data != NULL) {
1268       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1269     }
1270     if (pkg_entry != NULL) {
1271       mod_entry = pkg_entry->module();
1272     }
1273   }
1274 
1275   // If the archived class is from a module that has been patched at runtime,
1276   // the class cannot be loaded from the archive.
1277   if (mod_entry != NULL && mod_entry->is_patched()) {
1278     return false;
1279   }
1280 
1281   if (class_loader.is_null()) {
1282     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1283     // The NULL classloader can load archived class originated from the
1284     // "modules" jimage and the -Xbootclasspath/a. For class from the
1285     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1286     // by the NULL classloader.
1287     if (mod_entry != NULL) {
1288       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1289       // ModuleEntry's location agrees with the archived class' origination.
1290       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1291         return true; // Module class from the "module" jimage
1292       }
1293     }
1294 
1295     // If the archived class is not from the "module" jimage, the class can be
1296     // loaded by the NULL classloader if
1297     //
1298     // 1. the class is from the unamed package
1299     // 2. or, the class is not from a module defined in the NULL classloader
1300     // 3. or, the class is from an unamed module
1301     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1302       // the class is from the -Xbootclasspath/a
1303       if (pkg_string == NULL ||
1304           pkg_entry == NULL ||
1305           pkg_entry->in_unnamed_module()) {
1306         assert(mod_entry == NULL ||
1307                mod_entry == loader_data->unnamed_module(),
1308                "the unnamed module is not defined in the classloader");
1309         return true;
1310       }
1311     }
1312     return false;
1313   } else {
1314     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1315               ik, class_loader, pkg_string, pkg_name,
1316               pkg_entry, mod_entry, CHECK_(false));
1317     return res;
1318   }
1319 }
1320 
1321 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1322                                                    Handle class_loader,
1323                                                    Handle protection_domain, TRAPS) {
1324 
1325   if (ik != NULL) {
1326     Symbol* class_name = ik->name();
1327 
1328     bool visible = is_shared_class_visible(
1329                             class_name, ik, class_loader, CHECK_NULL);
1330     if (!visible) {
1331       return NULL;
1332     }
1333 
1334     // Resolve the superclass and interfaces. They must be the same
1335     // as in dump time, because the layout of <ik> depends on
1336     // the specific layout of ik->super() and ik->local_interfaces().
1337     //
1338     // If unexpected superclass or interfaces are found, we cannot
1339     // load <ik> from the shared archive.
1340 
1341     if (ik->super() != NULL) {
1342       Symbol*  cn = ik->super()->name();
1343       Klass *s = resolve_super_or_fail(class_name, cn,
1344                                        class_loader, protection_domain, true, CHECK_NULL);
1345       if (s != ik->super()) {
1346         // The dynamically resolved super class is not the same as the one we used during dump time,
1347         // so we cannot use ik.
1348         return NULL;
1349       } else {
1350         assert(s->is_shared(), "must be");
1351       }
1352     }
1353 
1354     Array<Klass*>* interfaces = ik->local_interfaces();
1355     int num_interfaces = interfaces->length();
1356     for (int index = 0; index < num_interfaces; index++) {
1357       Klass* k = interfaces->at(index);
1358       Symbol*  name  = k->name();
1359       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1360       if (k != i) {
1361         // The dynamically resolved interface class is not the same as the one we used during dump time,
1362         // so we cannot use ik.
1363         return NULL;
1364       } else {
1365         assert(i->is_shared(), "must be");
1366       }
1367     }
1368 
1369     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1370         ik, class_name, class_loader, protection_domain, CHECK_NULL);
1371     if (new_ik != NULL) {
1372       // The class is changed by CFLH. Return the new class. The shared class is
1373       // not used.
1374       return new_ik;
1375     }
1376 
1377     // Adjust methods to recover missing data.  They need addresses for
1378     // interpreter entry points and their default native method address
1379     // must be reset.
1380 
1381     // Updating methods must be done under a lock so multiple
1382     // threads don't update these in parallel
1383     //
1384     // Shared classes are all currently loaded by either the bootstrap or
1385     // internal parallel class loaders, so this will never cause a deadlock
1386     // on a custom class loader lock.
1387 
1388     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1389     {
1390       HandleMark hm(THREAD);
1391       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1392       check_loader_lock_contention(lockObject, THREAD);
1393       ObjectLocker ol(lockObject, THREAD, true);
1394       // prohibited package check assumes all classes loaded from archive call
1395       // restore_unshareable_info which calls ik->set_package()
1396       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1397     }
1398 
1399     ik->print_class_load_logging(loader_data, NULL, NULL);
1400 
1401     // For boot loader, ensure that GetSystemPackage knows that a class in this
1402     // package was loaded.
1403     if (class_loader.is_null()) {
1404       int path_index = ik->shared_classpath_index();
1405       ResourceMark rm;
1406       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1407     }
1408 
1409     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1410       // Only dump the classes that can be stored into CDS archive
1411       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1412         ResourceMark rm(THREAD);
1413         classlist_file->print_cr("%s", ik->name()->as_C_string());
1414         classlist_file->flush();
1415       }
1416     }
1417 
1418     // notify a class loaded from shared object
1419     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1420   }
1421 
1422   ik->set_has_passed_fingerprint_check(false);
1423   if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1424     uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1425     uint64_t cds_fp = ik->get_stored_fingerprint();
1426     if (aot_fp != 0 && aot_fp == cds_fp) {
1427       // This class matches with a class saved in an AOT library
1428       ik->set_has_passed_fingerprint_check(true);
1429     } else {
1430       ResourceMark rm;
1431       log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1432     }
1433   }
1434   return ik;
1435 }
1436 
1437 void SystemDictionary::clear_invoke_method_table() {
1438   SymbolPropertyEntry* spe = NULL;
1439   for (int index = 0; index < _invoke_method_table->table_size(); index++) {
1440     SymbolPropertyEntry* p = _invoke_method_table->bucket(index);
1441     while (p != NULL) {
1442       spe = p;
1443       p = p->next();
1444       _invoke_method_table->free_entry(spe);
1445     }
1446   }
1447 }
1448 #endif // INCLUDE_CDS
1449 
1450 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1451 
1452   if (class_loader.is_null()) {
1453     ResourceMark rm;
1454     PackageEntry* pkg_entry = NULL;
1455     bool search_only_bootloader_append = false;
1456     ClassLoaderData *loader_data = class_loader_data(class_loader);
1457 
1458     // Find the package in the boot loader's package entry table.
1459     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1460     if (pkg_name != NULL) {
1461       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1462     }
1463 
1464     // Prior to attempting to load the class, enforce the boot loader's
1465     // visibility boundaries.
1466     if (!Universe::is_module_initialized()) {
1467       // During bootstrapping, prior to module initialization, any
1468       // class attempting to be loaded must be checked against the
1469       // java.base packages in the boot loader's PackageEntryTable.
1470       // No class outside of java.base is allowed to be loaded during
1471       // this bootstrapping window.
1472       if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1473         // Class is either in the unnamed package or in
1474         // a named package within the unnamed module.  Either
1475         // case is outside of java.base, do not attempt to
1476         // load the class post java.base definition.  If
1477         // java.base has not been defined, let the class load
1478         // and its package will be checked later by
1479         // ModuleEntryTable::verify_javabase_packages.
1480         if (ModuleEntryTable::javabase_defined()) {
1481           return NULL;
1482         }
1483       } else {
1484         // Check that the class' package is defined within java.base.
1485         ModuleEntry* mod_entry = pkg_entry->module();
1486         Symbol* mod_entry_name = mod_entry->name();
1487         if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1488           return NULL;
1489         }
1490       }
1491     } else {
1492       // After the module system has been initialized, check if the class'
1493       // package is in a module defined to the boot loader.
1494       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1495         // Class is either in the unnamed package, in a named package
1496         // within a module not defined to the boot loader or in a
1497         // a named package within the unnamed module.  In all cases,
1498         // limit visibility to search for the class only in the boot
1499         // loader's append path.
1500         search_only_bootloader_append = true;
1501       }
1502     }
1503 
1504     // Prior to bootstrapping's module initialization, never load a class outside
1505     // of the boot loader's module path
1506     assert(Universe::is_module_initialized() ||
1507            !search_only_bootloader_append,
1508            "Attempt to load a class outside of boot loader's module path");
1509 
1510     // Search the shared system dictionary for classes preloaded into the
1511     // shared spaces.
1512     InstanceKlass* k = NULL;
1513     {
1514 #if INCLUDE_CDS
1515       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1516       k = load_shared_class(class_name, class_loader, THREAD);
1517 #endif
1518     }
1519 
1520     if (k == NULL) {
1521       // Use VM class loader
1522       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1523       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1524     }
1525 
1526     // find_or_define_instance_class may return a different InstanceKlass
1527     if (k != NULL) {
1528       InstanceKlass* defined_k =
1529         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1530       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1531         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1532         assert(defined_k != NULL, "Should have a klass if there's no exception");
1533         loader_data->add_to_deallocate_list(k);
1534         k = defined_k;
1535       } else if (HAS_PENDING_EXCEPTION) {
1536         loader_data->add_to_deallocate_list(k);
1537         return NULL;
1538       }
1539     }
1540     return k;
1541   } else {
1542     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1543     ResourceMark rm(THREAD);
1544 
1545     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1546     JavaThread* jt = (JavaThread*) THREAD;
1547 
1548     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1549                                ClassLoader::perf_app_classload_selftime(),
1550                                ClassLoader::perf_app_classload_count(),
1551                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1552                                jt->get_thread_stat()->perf_timers_addr(),
1553                                PerfClassTraceTime::CLASS_LOAD);
1554 
1555     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1556     // Translate to external class name format, i.e., convert '/' chars to '.'
1557     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1558 
1559     JavaValue result(T_OBJECT);
1560 
1561     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1562 
1563     // Call public unsynchronized loadClass(String) directly for all class loaders
1564     // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1565     // acquire a class-name based lock rather than the class loader object lock.
1566     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1567     // so the call to loadClassInternal() was not required.
1568     //
1569     // UnsyncloadClass flag means both call loadClass(String) and do
1570     // not acquire the class loader lock even for class loaders that are
1571     // not parallelCapable. This was a risky transitional
1572     // flag for diagnostic purposes only. It is risky to call
1573     // custom class loaders without synchronization.
1574     // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1575     // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1576     // Do NOT assume this will be supported in future releases.
1577     //
1578     // Added MustCallLoadClassInternal in case we discover in the field
1579     // a customer that counts on this call
1580     if (MustCallLoadClassInternal && has_loadClassInternal()) {
1581       JavaCalls::call_special(&result,
1582                               class_loader,
1583                               spec_klass,
1584                               vmSymbols::loadClassInternal_name(),
1585                               vmSymbols::string_class_signature(),
1586                               string,
1587                               CHECK_NULL);
1588     } else {
1589       JavaCalls::call_virtual(&result,
1590                               class_loader,
1591                               spec_klass,
1592                               vmSymbols::loadClass_name(),
1593                               vmSymbols::string_class_signature(),
1594                               string,
1595                               CHECK_NULL);
1596     }
1597 
1598     assert(result.get_type() == T_OBJECT, "just checking");
1599     oop obj = (oop) result.get_jobject();
1600 
1601     // Primitive classes return null since forName() can not be
1602     // used to obtain any of the Class objects representing primitives or void
1603     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1604       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1605       // For user defined Java class loaders, check that the name returned is
1606       // the same as that requested.  This check is done for the bootstrap
1607       // loader when parsing the class file.
1608       if (class_name == k->name()) {
1609         return k;
1610       }
1611     }
1612     // Class is not found or has the wrong name, return NULL
1613     return NULL;
1614   }
1615 }
1616 
1617 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1618 
1619   HandleMark hm(THREAD);
1620   ClassLoaderData* loader_data = k->class_loader_data();
1621   Handle class_loader_h(THREAD, loader_data->class_loader());
1622 
1623  // for bootstrap and other parallel classloaders don't acquire lock,
1624  // use placeholder token
1625  // If a parallelCapable class loader calls define_instance_class instead of
1626  // find_or_define_instance_class to get here, we have a timing
1627  // hole with systemDictionary updates and check_constraints
1628  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1629     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1630          compute_loader_lock_object(class_loader_h, THREAD)),
1631          "define called without lock");
1632   }
1633 
1634   // Check class-loading constraints. Throw exception if violation is detected.
1635   // Grabs and releases SystemDictionary_lock
1636   // The check_constraints/find_class call and update_dictionary sequence
1637   // must be "atomic" for a specific class/classloader pair so we never
1638   // define two different instanceKlasses for that class/classloader pair.
1639   // Existing classloaders will call define_instance_class with the
1640   // classloader lock held
1641   // Parallel classloaders will call find_or_define_instance_class
1642   // which will require a token to perform the define class
1643   Symbol*  name_h = k->name();
1644   Dictionary* dictionary = loader_data->dictionary();
1645   unsigned int d_hash = dictionary->compute_hash(name_h);
1646   check_constraints(d_hash, k, class_loader_h, true, CHECK);
1647 
1648   // Register class just loaded with class loader (placed in Vector)
1649   // Note we do this before updating the dictionary, as this can
1650   // fail with an OutOfMemoryError (if it does, we will *not* put this
1651   // class in the dictionary and will not update the class hierarchy).
1652   // JVMTI FollowReferences needs to find the classes this way.
1653   if (k->class_loader() != NULL) {
1654     methodHandle m(THREAD, Universe::loader_addClass_method());
1655     JavaValue result(T_VOID);
1656     JavaCallArguments args(class_loader_h);
1657     args.push_oop(Handle(THREAD, k->java_mirror()));
1658     JavaCalls::call(&result, m, &args, CHECK);
1659   }
1660 
1661   // Add the new class. We need recompile lock during update of CHA.
1662   {
1663     unsigned int p_hash = placeholders()->compute_hash(name_h);
1664     int p_index = placeholders()->hash_to_index(p_hash);
1665 
1666     MutexLocker mu_r(Compile_lock, THREAD);
1667 
1668     // Add to class hierarchy, initialize vtables, and do possible
1669     // deoptimizations.
1670     add_to_hierarchy(k, CHECK); // No exception, but can block
1671 
1672     // Add to systemDictionary - so other classes can see it.
1673     // Grabs and releases SystemDictionary_lock
1674     update_dictionary(d_hash, p_index, p_hash,
1675                       k, class_loader_h, THREAD);
1676   }
1677   k->eager_initialize(THREAD);
1678 
1679   // notify jvmti
1680   if (JvmtiExport::should_post_class_load()) {
1681       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1682       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1683 
1684   }
1685   class_define_event(k, loader_data);
1686 }
1687 
1688 // Support parallel classloading
1689 // All parallel class loaders, including bootstrap classloader
1690 // lock a placeholder entry for this class/class_loader pair
1691 // to allow parallel defines of different classes for this class loader
1692 // With AllowParallelDefine flag==true, in case they do not synchronize around
1693 // FindLoadedClass/DefineClass, calls, we check for parallel
1694 // loading for them, wait if a defineClass is in progress
1695 // and return the initial requestor's results
1696 // This flag does not apply to the bootstrap classloader.
1697 // With AllowParallelDefine flag==false, call through to define_instance_class
1698 // which will throw LinkageError: duplicate class definition.
1699 // False is the requested default.
1700 // For better performance, the class loaders should synchronize
1701 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1702 // potentially waste time reading and parsing the bytestream.
1703 // Note: VM callers should ensure consistency of k/class_name,class_loader
1704 // Be careful when modifying this code: once you have run
1705 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1706 // you need to find_and_remove it before returning.
1707 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1708 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1709                                                                InstanceKlass* k, TRAPS) {
1710 
1711   Symbol*  name_h = k->name(); // passed in class_name may be null
1712   ClassLoaderData* loader_data = class_loader_data(class_loader);
1713   Dictionary* dictionary = loader_data->dictionary();
1714 
1715   unsigned int d_hash = dictionary->compute_hash(name_h);
1716 
1717   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1718   unsigned int p_hash = placeholders()->compute_hash(name_h);
1719   int p_index = placeholders()->hash_to_index(p_hash);
1720   PlaceholderEntry* probe;
1721 
1722   {
1723     MutexLocker mu(SystemDictionary_lock, THREAD);
1724     // First check if class already defined
1725     if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1726       InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1727       if (check != NULL) {
1728         return check;
1729       }
1730     }
1731 
1732     // Acquire define token for this class/classloader
1733     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1734     // Wait if another thread defining in parallel
1735     // All threads wait - even those that will throw duplicate class: otherwise
1736     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1737     // if other thread has not finished updating dictionary
1738     while (probe->definer() != NULL) {
1739       SystemDictionary_lock->wait();
1740     }
1741     // Only special cases allow parallel defines and can use other thread's results
1742     // Other cases fall through, and may run into duplicate defines
1743     // caught by finding an entry in the SystemDictionary
1744     if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1745         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1746         SystemDictionary_lock->notify_all();
1747 #ifdef ASSERT
1748         InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1749         assert(check != NULL, "definer missed recording success");
1750 #endif
1751         return probe->instance_klass();
1752     } else {
1753       // This thread will define the class (even if earlier thread tried and had an error)
1754       probe->set_definer(THREAD);
1755     }
1756   }
1757 
1758   define_instance_class(k, THREAD);
1759 
1760   Handle linkage_exception = Handle(); // null handle
1761 
1762   // definer must notify any waiting threads
1763   {
1764     MutexLocker mu(SystemDictionary_lock, THREAD);
1765     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1766     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1767     if (probe != NULL) {
1768       if (HAS_PENDING_EXCEPTION) {
1769         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1770         CLEAR_PENDING_EXCEPTION;
1771       } else {
1772         probe->set_instance_klass(k);
1773       }
1774       probe->set_definer(NULL);
1775       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1776       SystemDictionary_lock->notify_all();
1777     }
1778   }
1779 
1780   // Can't throw exception while holding lock due to rank ordering
1781   if (linkage_exception() != NULL) {
1782     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1783   }
1784 
1785   return k;
1786 }
1787 
1788 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1789   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1790   if (class_loader.is_null()) {
1791     return Handle(THREAD, _system_loader_lock_obj);
1792   } else {
1793     return class_loader;
1794   }
1795 }
1796 
1797 // This method is added to check how often we have to wait to grab loader
1798 // lock. The results are being recorded in the performance counters defined in
1799 // ClassLoader::_sync_systemLoaderLockContentionRate and
1800 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1801 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1802   if (!UsePerfData) {
1803     return;
1804   }
1805 
1806   assert(!loader_lock.is_null(), "NULL lock object");
1807 
1808   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1809       == ObjectSynchronizer::owner_other) {
1810     // contention will likely happen, so increment the corresponding
1811     // contention counter.
1812     if (loader_lock() == _system_loader_lock_obj) {
1813       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1814     } else {
1815       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1816     }
1817   }
1818 }
1819 
1820 // ----------------------------------------------------------------------------
1821 // Lookup
1822 
1823 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1824                                             Symbol* class_name,
1825                                             Dictionary* dictionary) {
1826   assert_locked_or_safepoint(SystemDictionary_lock);
1827   int index = dictionary->hash_to_index(hash);
1828   return dictionary->find_class(index, hash, class_name);
1829 }
1830 
1831 
1832 // Basic find on classes in the midst of being loaded
1833 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1834                                            ClassLoaderData* loader_data) {
1835   assert_locked_or_safepoint(SystemDictionary_lock);
1836   unsigned int p_hash = placeholders()->compute_hash(class_name);
1837   int p_index = placeholders()->hash_to_index(p_hash);
1838   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1839 }
1840 
1841 
1842 // Used for assertions and verification only
1843 // Precalculating the hash and index is an optimization because there are many lookups
1844 // before adding the class.
1845 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1846   assert_locked_or_safepoint(SystemDictionary_lock);
1847   #ifndef ASSERT
1848   guarantee(VerifyBeforeGC      ||
1849             VerifyDuringGC      ||
1850             VerifyBeforeExit    ||
1851             VerifyDuringStartup ||
1852             VerifyAfterGC, "too expensive");
1853   #endif
1854 
1855   Dictionary* dictionary = loader_data->dictionary();
1856   unsigned int d_hash = dictionary->compute_hash(class_name);
1857   return find_class(d_hash, class_name, dictionary);
1858 }
1859 
1860 
1861 // ----------------------------------------------------------------------------
1862 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1863 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1864 // before a new class is used.
1865 
1866 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1867   assert(k != NULL, "just checking");
1868   assert_locked_or_safepoint(Compile_lock);
1869 
1870   // Link into hierachy. Make sure the vtables are initialized before linking into
1871   k->append_to_sibling_list();                    // add to superklass/sibling list
1872   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1873   k->set_init_state(InstanceKlass::loaded);
1874   // Now flush all code that depended on old class hierarchy.
1875   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1876   // Also, first reinitialize vtable because it may have gotten out of synch
1877   // while the new class wasn't connected to the class hierarchy.
1878   CodeCache::flush_dependents_on(k);
1879 }
1880 
1881 // ----------------------------------------------------------------------------
1882 // GC support
1883 
1884 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1885   roots_oops_do(blk, NULL);
1886 }
1887 
1888 
1889 #ifdef ASSERT
1890 class VerifySDReachableAndLiveClosure : public OopClosure {
1891 private:
1892   BoolObjectClosure* _is_alive;
1893 
1894   template <class T> void do_oop_work(T* p) {
1895     oop obj = oopDesc::load_decode_heap_oop(p);
1896     guarantee(_is_alive->do_object_b(obj), "Oop in protection domain cache table must be live");
1897   }
1898 
1899 public:
1900   VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1901 
1902   virtual void do_oop(oop* p)       { do_oop_work(p); }
1903   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1904 };
1905 #endif
1906 
1907 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1908 // Note: anonymous classes are not in the SD.
1909 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1910                                     GCTimer* gc_timer,
1911                                     bool do_cleaning) {
1912 
1913 
1914   bool unloading_occurred;
1915   {
1916     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1917 
1918     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1919     unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1920                                                             do_cleaning);
1921   }
1922 
1923   if (unloading_occurred) {
1924     GCTraceTime(Debug, gc, phases) t("Dictionary", gc_timer);
1925     constraints()->purge_loader_constraints();
1926     resolution_errors()->purge_resolution_errors();
1927   }
1928 
1929   {
1930     GCTraceTime(Debug, gc, phases) t("ProtectionDomainCacheTable", gc_timer);
1931     // Oops referenced by the protection domain cache table may get unreachable independently
1932     // of the class loader (eg. cached protection domain oops). So we need to
1933     // explicitly unlink them here.
1934     _pd_cache_table->unlink(is_alive);
1935 
1936 #ifdef ASSERT
1937     VerifySDReachableAndLiveClosure cl(is_alive);
1938     _pd_cache_table->oops_do(&cl);
1939 #endif
1940   }
1941 
1942   if (do_cleaning) {
1943     GCTraceTime(Debug, gc, phases) t("ResolvedMethodTable", gc_timer);
1944     ResolvedMethodTable::unlink(is_alive);
1945   }
1946 
1947   return unloading_occurred;
1948 }
1949 
1950 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1951   strong->do_oop(&_java_system_loader);
1952   strong->do_oop(&_java_platform_loader);
1953   strong->do_oop(&_system_loader_lock_obj);
1954   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1955 
1956   // Do strong roots marking if the closures are the same.
1957   if (strong == weak || !ClassUnloading) {
1958     // Only the protection domain oops contain references into the heap. Iterate
1959     // over all of them.
1960     _pd_cache_table->oops_do(strong);
1961   } else {
1962    if (weak != NULL) {
1963      _pd_cache_table->oops_do(weak);
1964    }
1965   }
1966 
1967   // Visit extra methods
1968   invoke_method_table()->oops_do(strong);
1969 
1970   if (weak != NULL) {
1971     ResolvedMethodTable::oops_do(weak);
1972   }
1973 }
1974 
1975 void SystemDictionary::oops_do(OopClosure* f) {
1976   f->do_oop(&_java_system_loader);
1977   f->do_oop(&_java_platform_loader);
1978   f->do_oop(&_system_loader_lock_obj);
1979   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1980 
1981   // Only the protection domain oops contain references into the heap. Iterate
1982   // over all of them.
1983   _pd_cache_table->oops_do(f);
1984 
1985   // Visit extra methods
1986   invoke_method_table()->oops_do(f);
1987 
1988   ResolvedMethodTable::oops_do(f);
1989 }
1990 
1991 // CDS: scan and relocate all classes in the system dictionary.
1992 void SystemDictionary::classes_do(MetaspaceClosure* it) {
1993   ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(it);
1994 }
1995 
1996 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1997 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1998   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1999     it->push(well_known_klass_addr((WKID)id));
2000   }
2001 }
2002 
2003 void SystemDictionary::methods_do(void f(Method*)) {
2004   // Walk methods in loaded classes
2005   ClassLoaderDataGraph::methods_do(f);
2006   // Walk method handle intrinsics
2007   invoke_method_table()->methods_do(f);
2008 }
2009 
2010 class RemoveClassesClosure : public CLDClosure {
2011   public:
2012     void do_cld(ClassLoaderData* cld) {
2013       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
2014         cld->dictionary()->remove_classes_in_error_state();
2015       }
2016     }
2017 };
2018 
2019 void SystemDictionary::remove_classes_in_error_state() {
2020   ClassLoaderData::the_null_class_loader_data()->dictionary()->remove_classes_in_error_state();
2021   RemoveClassesClosure rcc;
2022   ClassLoaderDataGraph::cld_do(&rcc);
2023 }
2024 
2025 // ----------------------------------------------------------------------------
2026 // Lazily load klasses
2027 
2028 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
2029   // if multiple threads calling this function, only one thread will load
2030   // the class.  The other threads will find the loaded version once the
2031   // class is loaded.
2032   Klass* aos = _abstract_ownable_synchronizer_klass;
2033   if (aos == NULL) {
2034     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
2035     // Force a fence to prevent any read before the write completes
2036     OrderAccess::fence();
2037     _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
2038   }
2039 }
2040 
2041 // ----------------------------------------------------------------------------
2042 // Initialization
2043 
2044 void SystemDictionary::initialize(TRAPS) {
2045   // Allocate arrays
2046   _placeholders        = new PlaceholderTable(_placeholder_table_size);
2047   _number_of_modifications = 0;
2048   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
2049   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
2050   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
2051   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
2052 
2053 #if INCLUDE_VBC
2054   if (ValueBasedClasses == NULL) {
2055     // Quick dirty hard-coded JDK value classes...
2056     ValueBasedClasses = "java/lang/Runtime$Version,"
2057       "java/time/Duration,"
2058       "java/time/Instant,"
2059       "java/time/LocalDate,"
2060       "java/time/LocalDateTime,"
2061       "java/time/LocalTime,"
2062       "java/time/MonthDay,"
2063       "java/time/OffsetDateTime,"
2064       "java/time/OffsetTime,"
2065       "java/time/Period,"
2066       "java/time/Year,"
2067       "java/time/YearMonth,"
2068       "java/time/ZonedDateTime,"
2069       "java/time/ZoneId,"
2070       "java/time/ZoneOffset,"
2071       "java/time/chrono/HijrahDate,"
2072       "java/time/chrono/JapaneseDate,"
2073       "java/time/chrono/MinguoDate,"
2074       "java/time/chrono/ThaiBuddhistDate,"
2075       "java/util/KeyValueHolder,"
2076       "java/util/Optional,"
2077       "java/util/OptionalDouble,"
2078       "java/util/OptionalInt,"
2079       "java/util/OptionalLong";
2080   }
2081   if (ValueBasedClasses != NULL) {
2082     Symbol* name_sym;
2083     _value_based_classes = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<Symbol*>(3, true);
2084     char* name = os::strdup_check_oom(ValueBasedClasses);
2085     char* next = strchr(name, ',');
2086     while (next != NULL) {
2087       *next = '\0';
2088       name_sym = SymbolTable::new_permanent_symbol(name, CHECK);
2089       _value_based_classes->append(name_sym);
2090       name = next + 1;
2091       next = strchr(name, ',');
2092     }
2093     name_sym = SymbolTable::new_permanent_symbol(name, CHECK);
2094     _value_based_classes->append(name_sym);
2095   }
2096 #endif
2097 
2098   // Allocate private object used as system class loader lock
2099   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
2100   // Initialize basic classes
2101   initialize_preloaded_classes(CHECK);
2102 }
2103 
2104 // Compact table of directions on the initialization of klasses:
2105 static const short wk_init_info[] = {
2106   #define WK_KLASS_INIT_INFO(name, symbol, option) \
2107     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
2108           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
2109       | (int)SystemDictionary::option ),
2110   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
2111   #undef WK_KLASS_INIT_INFO
2112   0
2113 };
2114 
2115 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
2116   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2117   int  info = wk_init_info[id - FIRST_WKID];
2118   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
2119   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
2120   InstanceKlass** klassp = &_well_known_klasses[id];
2121 
2122   bool must_load;
2123 #if INCLUDE_JVMCI
2124   if (EnableJVMCI) {
2125     // If JVMCI is enabled we require its classes to be found.
2126     must_load = (init_opt < SystemDictionary::Opt) || (init_opt == SystemDictionary::Jvmci);
2127   } else
2128 #endif
2129   {
2130     must_load = (init_opt < SystemDictionary::Opt);
2131   }
2132 
2133   if ((*klassp) == NULL) {
2134     Klass* k;
2135     if (must_load) {
2136       k = resolve_or_fail(symbol, true, CHECK_0); // load required class
2137     } else {
2138       k = resolve_or_null(symbol,       CHECK_0); // load optional klass
2139     }
2140     (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
2141   }
2142   return ((*klassp) != NULL);
2143 }
2144 
2145 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
2146   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
2147   for (int id = (int)start_id; id < (int)limit_id; id++) {
2148     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2149     int info = wk_init_info[id - FIRST_WKID];
2150     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
2151     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
2152 
2153     initialize_wk_klass((WKID)id, opt, CHECK);
2154   }
2155 
2156   // move the starting value forward to the limit:
2157   start_id = limit_id;
2158 }
2159 
2160 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
2161   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
2162 
2163   // Create the ModuleEntry for java.base.  This call needs to be done here,
2164   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
2165   ClassLoader::classLoader_init2(CHECK);
2166 
2167   // Preload commonly used klasses
2168   WKID scan = FIRST_WKID;
2169   // first do Object, then String, Class
2170 #if INCLUDE_CDS
2171   if (UseSharedSpaces) {
2172     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
2173     // Initialize the constant pool for the Object_class
2174     Object_klass()->constants()->restore_unshareable_info(CHECK);
2175     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2176   } else
2177 #endif
2178   {
2179     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2180   }
2181 
2182   // Calculate offsets for String and Class classes since they are loaded and
2183   // can be used after this point.
2184   java_lang_String::compute_offsets();
2185   java_lang_Class::compute_offsets();
2186 
2187   // Fixup mirrors for classes loaded before java.lang.Class.
2188   // These calls iterate over the objects currently in the perm gen
2189   // so calling them at this point is matters (not before when there
2190   // are fewer objects and not later after there are more objects
2191   // in the perm gen.
2192   Universe::initialize_basic_type_mirrors(CHECK);
2193   Universe::fixup_mirrors(CHECK);
2194 
2195   // do a bunch more:
2196   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2197 
2198   // Preload ref klasses and set reference types
2199   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2200   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2201 
2202   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2203   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2204   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2205   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2206   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2207 
2208   // JSR 292 classes
2209   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2210   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2211   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
2212   initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
2213   initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
2214 
2215   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2216   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2217   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2218   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2219   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2220   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2221   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2222   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2223   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2224   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2225 
2226   { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2227     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2228     _has_loadClassInternal = (method != NULL);
2229   }
2230   { // Compute whether we should use checkPackageAccess or NOT
2231     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2232     _has_checkPackageAccess = (method != NULL);
2233   }
2234 }
2235 
2236 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2237 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2238 BasicType SystemDictionary::box_klass_type(Klass* k) {
2239   assert(k != NULL, "");
2240   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2241     if (_box_klasses[i] == k)
2242       return (BasicType)i;
2243   }
2244   return T_OBJECT;
2245 }
2246 
2247 // Constraints on class loaders. The details of the algorithm can be
2248 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2249 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2250 // that the dictionary needs to maintain a set of contraints that
2251 // must be satisfied by all classes in the dictionary.
2252 // if defining is true, then LinkageError if already in dictionary
2253 // if initiating loader, then ok if InstanceKlass matches existing entry
2254 
2255 void SystemDictionary::check_constraints(unsigned int d_hash,
2256                                          InstanceKlass* k,
2257                                          Handle class_loader, bool defining,
2258                                          TRAPS) {
2259   const char *linkage_error1 = NULL;
2260   const char *linkage_error2 = NULL;
2261   {
2262     Symbol*  name  = k->name();
2263     ClassLoaderData *loader_data = class_loader_data(class_loader);
2264 
2265     MutexLocker mu(SystemDictionary_lock, THREAD);
2266 
2267     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2268     if (check != NULL) {
2269       // if different InstanceKlass - duplicate class definition,
2270       // else - ok, class loaded by a different thread in parallel,
2271       // we should only have found it if it was done loading and ok to use
2272       // dictionary only holds instance classes, placeholders
2273       // also holds array classes
2274 
2275       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2276       if ((defining == true) || (k != check)) {
2277         linkage_error1 = "loader (instance of ";
2278         linkage_error2 = "): attempted duplicate class definition for name: \"";
2279       } else {
2280         return;
2281       }
2282     }
2283 
2284 #ifdef ASSERT
2285     Symbol* ph_check = find_placeholder(name, loader_data);
2286     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2287 #endif
2288 
2289     if (linkage_error1 == NULL) {
2290       if (constraints()->check_or_update(k, class_loader, name) == false) {
2291         linkage_error1 = "loader constraint violation: loader (instance of ";
2292         linkage_error2 = ") previously initiated loading for a different type with name \"";
2293       }
2294     }
2295   }
2296 
2297   // Throw error now if needed (cannot throw while holding
2298   // SystemDictionary_lock because of rank ordering)
2299 
2300   if (linkage_error1) {
2301     ResourceMark rm(THREAD);
2302     const char* class_loader_name = loader_name(class_loader());
2303     char* type_name = k->name()->as_C_string();
2304     size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2305       strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2306     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2307     jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2308     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2309   }
2310 }
2311 
2312 
2313 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2314 // have been called.
2315 void SystemDictionary::update_dictionary(unsigned int d_hash,
2316                                          int p_index, unsigned int p_hash,
2317                                          InstanceKlass* k,
2318                                          Handle class_loader,
2319                                          TRAPS) {
2320   // Compile_lock prevents systemDictionary updates during compilations
2321   assert_locked_or_safepoint(Compile_lock);
2322   Symbol*  name  = k->name();
2323   ClassLoaderData *loader_data = class_loader_data(class_loader);
2324 
2325   {
2326     MutexLocker mu1(SystemDictionary_lock, THREAD);
2327 
2328     // See whether biased locking is enabled and if so set it for this
2329     // klass.
2330     // Note that this must be done past the last potential blocking
2331     // point / safepoint. We enable biased locking lazily using a
2332     // VM_Operation to iterate the SystemDictionary and installing the
2333     // biasable mark word into each InstanceKlass's prototype header.
2334     // To avoid race conditions where we accidentally miss enabling the
2335     // optimization for one class in the process of being added to the
2336     // dictionary, we must not safepoint after the test of
2337     // BiasedLocking::enabled().
2338     if (UseBiasedLocking && BiasedLocking::enabled()) {
2339       // Set biased locking bit for all loaded classes; it will be
2340       // cleared if revocation occurs too often for this type
2341       // NOTE that we must only do this when the class is initally
2342       // defined, not each time it is referenced from a new class loader
2343       if (k->class_loader() == class_loader()) {
2344         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2345       }
2346     }
2347 
2348     // Make a new dictionary entry.
2349     Dictionary* dictionary = loader_data->dictionary();
2350     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2351     if (sd_check == NULL) {
2352       dictionary->add_klass(d_hash, name, k);
2353       notice_modification();
2354     }
2355   #ifdef ASSERT
2356     sd_check = find_class(d_hash, name, dictionary);
2357     assert (sd_check != NULL, "should have entry in dictionary");
2358     // Note: there may be a placeholder entry: for circularity testing
2359     // or for parallel defines
2360   #endif
2361     SystemDictionary_lock->notify_all();
2362   }
2363 }
2364 
2365 
2366 // Try to find a class name using the loader constraints.  The
2367 // loader constraints might know about a class that isn't fully loaded
2368 // yet and these will be ignored.
2369 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2370                     Symbol* class_name, Handle class_loader, TRAPS) {
2371 
2372   // First see if it has been loaded directly.
2373   // Force the protection domain to be null.  (This removes protection checks.)
2374   Handle no_protection_domain;
2375   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2376                                               no_protection_domain, CHECK_NULL);
2377   if (klass != NULL)
2378     return klass;
2379 
2380   // Now look to see if it has been loaded elsewhere, and is subject to
2381   // a loader constraint that would require this loader to return the
2382   // klass that is already loaded.
2383   if (FieldType::is_array(class_name)) {
2384     // For array classes, their Klass*s are not kept in the
2385     // constraint table. The element Klass*s are.
2386     FieldArrayInfo fd;
2387     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2388     if (t != T_OBJECT) {
2389       klass = Universe::typeArrayKlassObj(t);
2390     } else {
2391       MutexLocker mu(SystemDictionary_lock, THREAD);
2392       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2393     }
2394     // If element class already loaded, allocate array klass
2395     if (klass != NULL) {
2396       klass = klass->array_klass_or_null(fd.dimension());
2397     }
2398   } else {
2399     MutexLocker mu(SystemDictionary_lock, THREAD);
2400     // Non-array classes are easy: simply check the constraint table.
2401     klass = constraints()->find_constrained_klass(class_name, class_loader);
2402   }
2403 
2404   return klass;
2405 }
2406 
2407 
2408 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2409                                              Handle class_loader1,
2410                                              Handle class_loader2,
2411                                              Thread* THREAD) {
2412   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2413   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2414 
2415   Symbol* constraint_name = NULL;
2416   if (!FieldType::is_array(class_name)) {
2417     constraint_name = class_name;
2418   } else {
2419     // For array classes, their Klass*s are not kept in the
2420     // constraint table. The element classes are.
2421     FieldArrayInfo fd;
2422     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2423     // primitive types always pass
2424     if (t != T_OBJECT) {
2425       return true;
2426     } else {
2427       constraint_name = fd.object_key();
2428     }
2429   }
2430 
2431   Dictionary* dictionary1 = loader_data1->dictionary();
2432   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2433 
2434   Dictionary* dictionary2 = loader_data2->dictionary();
2435   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2436 
2437   {
2438     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2439     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2440     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2441     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2442                                     klass2, class_loader2);
2443   }
2444 }
2445 
2446 // Add entry to resolution error table to record the error when the first
2447 // attempt to resolve a reference to a class has failed.
2448 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2449                                             Symbol* error, Symbol* message) {
2450   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2451   int index = resolution_errors()->hash_to_index(hash);
2452   {
2453     MutexLocker ml(SystemDictionary_lock, Thread::current());
2454     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2455   }
2456 }
2457 
2458 // Delete a resolution error for RedefineClasses for a constant pool is going away
2459 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2460   resolution_errors()->delete_entry(pool);
2461 }
2462 
2463 // Lookup resolution error table. Returns error if found, otherwise NULL.
2464 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2465                                                 Symbol** message) {
2466   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2467   int index = resolution_errors()->hash_to_index(hash);
2468   {
2469     MutexLocker ml(SystemDictionary_lock, Thread::current());
2470     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2471     if (entry != NULL) {
2472       *message = entry->message();
2473       return entry->error();
2474     } else {
2475       return NULL;
2476     }
2477   }
2478 }
2479 
2480 
2481 // Signature constraints ensure that callers and callees agree about
2482 // the meaning of type names in their signatures.  This routine is the
2483 // intake for constraints.  It collects them from several places:
2484 //
2485 //  * LinkResolver::resolve_method (if check_access is true) requires
2486 //    that the resolving class (the caller) and the defining class of
2487 //    the resolved method (the callee) agree on each type in the
2488 //    method's signature.
2489 //
2490 //  * LinkResolver::resolve_interface_method performs exactly the same
2491 //    checks.
2492 //
2493 //  * LinkResolver::resolve_field requires that the constant pool
2494 //    attempting to link to a field agree with the field's defining
2495 //    class about the type of the field signature.
2496 //
2497 //  * klassVtable::initialize_vtable requires that, when a class
2498 //    overrides a vtable entry allocated by a superclass, that the
2499 //    overriding method (i.e., the callee) agree with the superclass
2500 //    on each type in the method's signature.
2501 //
2502 //  * klassItable::initialize_itable requires that, when a class fills
2503 //    in its itables, for each non-abstract method installed in an
2504 //    itable, the method (i.e., the callee) agree with the interface
2505 //    on each type in the method's signature.
2506 //
2507 // All those methods have a boolean (check_access, checkconstraints)
2508 // which turns off the checks.  This is used from specialized contexts
2509 // such as bootstrapping, dumping, and debugging.
2510 //
2511 // No direct constraint is placed between the class and its
2512 // supertypes.  Constraints are only placed along linked relations
2513 // between callers and callees.  When a method overrides or implements
2514 // an abstract method in a supertype (superclass or interface), the
2515 // constraints are placed as if the supertype were the caller to the
2516 // overriding method.  (This works well, since callers to the
2517 // supertype have already established agreement between themselves and
2518 // the supertype.)  As a result of all this, a class can disagree with
2519 // its supertype about the meaning of a type name, as long as that
2520 // class neither calls a relevant method of the supertype, nor is
2521 // called (perhaps via an override) from the supertype.
2522 //
2523 //
2524 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2525 //
2526 // Make sure all class components (including arrays) in the given
2527 // signature will be resolved to the same class in both loaders.
2528 // Returns the name of the type that failed a loader constraint check, or
2529 // NULL if no constraint failed.  No exception except OOME is thrown.
2530 // Arrays are not added to the loader constraint table, their elements are.
2531 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2532                                                Handle loader1, Handle loader2,
2533                                                bool is_method, TRAPS)  {
2534   // Nothing to do if loaders are the same.
2535   if (loader1() == loader2()) {
2536     return NULL;
2537   }
2538 
2539   SignatureStream sig_strm(signature, is_method);
2540   while (!sig_strm.is_done()) {
2541     if (sig_strm.is_object()) {
2542       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2543       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2544         return sig;
2545       }
2546     }
2547     sig_strm.next();
2548   }
2549   return NULL;
2550 }
2551 
2552 
2553 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2554                                                             Symbol* signature,
2555                                                             TRAPS) {
2556   methodHandle empty;
2557   assert(MethodHandles::is_signature_polymorphic(iid) &&
2558          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2559          iid != vmIntrinsics::_invokeGeneric,
2560          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2561 
2562   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2563   int          index = invoke_method_table()->hash_to_index(hash);
2564   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2565   methodHandle m;
2566   if (spe == NULL || spe->method() == NULL) {
2567     spe = NULL;
2568     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2569     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2570     if (!Arguments::is_interpreter_only()) {
2571       // Generate a compiled form of the MH intrinsic.
2572       AdapterHandlerLibrary::create_native_wrapper(m);
2573       // Check if have the compiled code.
2574       if (!m->has_compiled_code()) {
2575         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2576                    "Out of space in CodeCache for method handle intrinsic", empty);
2577       }
2578     }
2579     // Now grab the lock.  We might have to throw away the new method,
2580     // if a racing thread has managed to install one at the same time.
2581     {
2582       MutexLocker ml(SystemDictionary_lock, THREAD);
2583       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2584       if (spe == NULL)
2585         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2586       if (spe->method() == NULL)
2587         spe->set_method(m());
2588     }
2589   }
2590 
2591   assert(spe != NULL && spe->method() != NULL, "");
2592   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2593          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2594          "MH intrinsic invariant");
2595   return spe->method();
2596 }
2597 
2598 // Helper for unpacking the return value from linkMethod and linkCallSite.
2599 static methodHandle unpack_method_and_appendix(Handle mname,
2600                                                Klass* accessing_klass,
2601                                                objArrayHandle appendix_box,
2602                                                Handle* appendix_result,
2603                                                TRAPS) {
2604   methodHandle empty;
2605   if (mname.not_null()) {
2606     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2607     if (m != NULL) {
2608       oop appendix = appendix_box->obj_at(0);
2609       if (TraceMethodHandles) {
2610     #ifndef PRODUCT
2611         ttyLocker ttyl;
2612         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2613         m->print();
2614         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2615         tty->cr();
2616     #endif //PRODUCT
2617       }
2618       (*appendix_result) = Handle(THREAD, appendix);
2619       // the target is stored in the cpCache and if a reference to this
2620       // MethodName is dropped we need a way to make sure the
2621       // class_loader containing this method is kept alive.
2622       // FIXME: the appendix might also preserve this dependency.
2623       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2624       this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2625       return methodHandle(THREAD, m);
2626     }
2627   }
2628   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2629   return empty;
2630 }
2631 
2632 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2633                                                           Symbol* name,
2634                                                           Symbol* signature,
2635                                                           Klass* accessing_klass,
2636                                                           Handle *appendix_result,
2637                                                           Handle *method_type_result,
2638                                                           TRAPS) {
2639   methodHandle empty;
2640   assert(THREAD->can_call_java() ,"");
2641   Handle method_type =
2642     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2643 
2644   int ref_kind = JVM_REF_invokeVirtual;
2645   oop name_oop = StringTable::intern(name, CHECK_(empty));
2646   Handle name_str (THREAD, name_oop);
2647   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2648   assert(appendix_box->obj_at(0) == NULL, "");
2649 
2650   // This should not happen.  JDK code should take care of that.
2651   if (accessing_klass == NULL || method_type.is_null()) {
2652     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2653   }
2654 
2655   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2656   JavaCallArguments args;
2657   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2658   args.push_int(ref_kind);
2659   args.push_oop(Handle(THREAD, klass->java_mirror()));
2660   args.push_oop(name_str);
2661   args.push_oop(method_type);
2662   args.push_oop(appendix_box);
2663   JavaValue result(T_OBJECT);
2664   JavaCalls::call_static(&result,
2665                          SystemDictionary::MethodHandleNatives_klass(),
2666                          vmSymbols::linkMethod_name(),
2667                          vmSymbols::linkMethod_signature(),
2668                          &args, CHECK_(empty));
2669   Handle mname(THREAD, (oop) result.get_jobject());
2670   (*method_type_result) = method_type;
2671   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2672 }
2673 
2674 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2675 // We must ensure that all class loaders everywhere will reach this class, for any client.
2676 // This is a safe bet for public classes in java.lang, such as Object and String.
2677 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2678 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2679 static bool is_always_visible_class(oop mirror) {
2680   Klass* klass = java_lang_Class::as_Klass(mirror);
2681   if (klass->is_objArray_klass()) {
2682     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2683   }
2684   if (klass->is_typeArray_klass()) {
2685     return true; // primitive array
2686   }
2687   assert(klass->is_instance_klass(), "%s", klass->external_name());
2688   return klass->is_public() &&
2689          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2690           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2691 }
2692 
2693 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2694 // signature, as interpreted relative to the given class loader.
2695 // Because of class loader constraints, all method handle usage must be
2696 // consistent with this loader.
2697 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2698                                                  Klass* accessing_klass,
2699                                                  TRAPS) {
2700   Handle empty;
2701   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2702   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2703   int          index = invoke_method_table()->hash_to_index(hash);
2704   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2705   if (spe != NULL && spe->method_type() != NULL) {
2706     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2707     return Handle(THREAD, spe->method_type());
2708   } else if (!THREAD->can_call_java()) {
2709     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2710     return Handle();  // do not attempt from within compiler, unless it was cached
2711   }
2712 
2713   Handle class_loader, protection_domain;
2714   if (accessing_klass != NULL) {
2715     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2716     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2717   }
2718   bool can_be_cached = true;
2719   int npts = ArgumentCount(signature).size();
2720   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2721   int arg = 0;
2722   Handle rt; // the return type from the signature
2723   ResourceMark rm(THREAD);
2724   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2725     oop mirror = NULL;
2726     if (can_be_cached) {
2727       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2728       mirror = ss.as_java_mirror(Handle(), Handle(),
2729                                  SignatureStream::ReturnNull, CHECK_(empty));
2730       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2731         // Fall back to accessing_klass context.
2732         can_be_cached = false;
2733       }
2734     }
2735     if (!can_be_cached) {
2736       // Resolve, throwing a real error if it doesn't work.
2737       mirror = ss.as_java_mirror(class_loader, protection_domain,
2738                                  SignatureStream::NCDFError, CHECK_(empty));
2739     }
2740     assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2741     if (ss.at_return_type())
2742       rt = Handle(THREAD, mirror);
2743     else
2744       pts->obj_at_put(arg++, mirror);
2745 
2746     // Check accessibility.
2747     if (ss.is_object() && accessing_klass != NULL) {
2748       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2749       mirror = NULL;  // safety
2750       // Emulate ConstantPool::verify_constant_pool_resolve.
2751       if (sel_klass->is_objArray_klass())
2752         sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2753       if (sel_klass->is_instance_klass()) {
2754         LinkResolver::check_klass_accessability(accessing_klass, sel_klass, CHECK_(empty));
2755       }
2756     }
2757   }
2758   assert(arg == npts, "");
2759 
2760   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2761   JavaCallArguments args(Handle(THREAD, rt()));
2762   args.push_oop(pts);
2763   JavaValue result(T_OBJECT);
2764   JavaCalls::call_static(&result,
2765                          SystemDictionary::MethodHandleNatives_klass(),
2766                          vmSymbols::findMethodHandleType_name(),
2767                          vmSymbols::findMethodHandleType_signature(),
2768                          &args, CHECK_(empty));
2769   Handle method_type(THREAD, (oop) result.get_jobject());
2770 
2771   if (can_be_cached) {
2772     // We can cache this MethodType inside the JVM.
2773     MutexLocker ml(SystemDictionary_lock, THREAD);
2774     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2775     if (spe == NULL)
2776       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2777     if (spe->method_type() == NULL) {
2778       spe->set_method_type(method_type());
2779     }
2780   }
2781 
2782   // report back to the caller with the MethodType
2783   return method_type;
2784 }
2785 
2786 // Ask Java code to find or construct a method handle constant.
2787 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2788                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2789                                                      Klass* callee,
2790                                                      Symbol* name_sym,
2791                                                      Symbol* signature,
2792                                                      TRAPS) {
2793   Handle empty;
2794   Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2795   Handle type;
2796   if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2797     type = find_method_handle_type(signature, caller, CHECK_(empty));
2798   } else if (caller == NULL) {
2799     // This should not happen.  JDK code should take care of that.
2800     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2801   } else {
2802     ResourceMark rm(THREAD);
2803     SignatureStream ss(signature, false);
2804     if (!ss.is_done()) {
2805       oop mirror = ss.as_java_mirror(Handle(THREAD, caller->class_loader()),
2806                                      Handle(THREAD, caller->protection_domain()),
2807                                      SignatureStream::NCDFError, CHECK_(empty));
2808       type = Handle(THREAD, mirror);
2809       ss.next();
2810       if (!ss.is_done())  type = Handle();  // error!
2811     }
2812   }
2813   if (type.is_null()) {
2814     THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2815   }
2816 
2817   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2818   JavaCallArguments args;
2819   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2820   args.push_int(ref_kind);
2821   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2822   args.push_oop(name);
2823   args.push_oop(type);
2824   JavaValue result(T_OBJECT);
2825   JavaCalls::call_static(&result,
2826                          SystemDictionary::MethodHandleNatives_klass(),
2827                          vmSymbols::linkMethodHandleConstant_name(),
2828                          vmSymbols::linkMethodHandleConstant_signature(),
2829                          &args, CHECK_(empty));
2830   return Handle(THREAD, (oop) result.get_jobject());
2831 }
2832 
2833 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2834 // name and signature, as interpreted relative to the given class loader.
2835 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller,
2836                                                               Handle bootstrap_specifier,
2837                                                               Symbol* name,
2838                                                               Symbol* type,
2839                                                               Handle *appendix_result,
2840                                                               Handle *method_type_result,
2841                                                               TRAPS) {
2842   methodHandle empty;
2843   Handle bsm, info;
2844   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2845     bsm = bootstrap_specifier;
2846   } else {
2847     assert(bootstrap_specifier->is_objArray(), "");
2848     objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2849     int len = args->length();
2850     assert(len >= 1, "");
2851     bsm = Handle(THREAD, args->obj_at(0));
2852     if (len > 1) {
2853       objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2854       for (int i = 1; i < len; i++)
2855         args1->obj_at_put(i-1, args->obj_at(i));
2856       info = Handle(THREAD, args1);
2857     }
2858   }
2859   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2860             "caller must supply a valid BSM");
2861 
2862   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2863   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2864 
2865   // This should not happen.  JDK code should take care of that.
2866   if (caller == NULL || method_type.is_null()) {
2867     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2868   }
2869 
2870   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2871   assert(appendix_box->obj_at(0) == NULL, "");
2872 
2873   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2874   JavaCallArguments args;
2875   args.push_oop(Handle(THREAD, caller->java_mirror()));
2876   args.push_oop(bsm);
2877   args.push_oop(method_name);
2878   args.push_oop(method_type);
2879   args.push_oop(info);
2880   args.push_oop(appendix_box);
2881   JavaValue result(T_OBJECT);
2882   JavaCalls::call_static(&result,
2883                          SystemDictionary::MethodHandleNatives_klass(),
2884                          vmSymbols::linkCallSite_name(),
2885                          vmSymbols::linkCallSite_signature(),
2886                          &args, CHECK_(empty));
2887   Handle mname(THREAD, (oop) result.get_jobject());
2888   (*method_type_result) = method_type;
2889   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2890 }
2891 
2892 // Protection domain cache table handling
2893 
2894 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2895   return _pd_cache_table->get(protection_domain);
2896 }
2897 
2898 #if INCLUDE_CDS
2899 void SystemDictionary::reorder_dictionary_for_sharing() {
2900   ClassLoaderData::the_null_class_loader_data()->dictionary()->reorder_dictionary_for_sharing();
2901 }
2902 #endif
2903 
2904 size_t SystemDictionary::count_bytes_for_buckets() {
2905   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_buckets();
2906 }
2907 
2908 size_t SystemDictionary::count_bytes_for_table() {
2909   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_table();
2910 }
2911 
2912 void SystemDictionary::copy_buckets(char* top, char* end) {
2913   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_buckets(top, end);
2914 }
2915 
2916 void SystemDictionary::copy_table(char* top, char* end) {
2917   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_table(top, end);
2918 }
2919 
2920 // ----------------------------------------------------------------------------
2921 void SystemDictionary::print_shared(outputStream *st) {
2922   shared_dictionary()->print_on(st);
2923 }
2924 
2925 void SystemDictionary::print_on(outputStream *st) {
2926   if (shared_dictionary() != NULL) {
2927     st->print_cr("Shared Dictionary");
2928     shared_dictionary()->print_on(st);
2929     st->cr();
2930   }
2931 
2932   GCMutexLocker mu(SystemDictionary_lock);
2933 
2934   ClassLoaderDataGraph::print_dictionary(st);
2935 
2936   // Placeholders
2937   placeholders()->print_on(st);
2938   st->cr();
2939 
2940   // loader constraints - print under SD_lock
2941   constraints()->print_on(st);
2942   st->cr();
2943 
2944   _pd_cache_table->print_on(st);
2945   st->cr();
2946 }
2947 
2948 void SystemDictionary::verify() {
2949   guarantee(constraints() != NULL,
2950             "Verify of loader constraints failed");
2951   guarantee(placeholders()->number_of_entries() >= 0,
2952             "Verify of placeholders failed");
2953 
2954   GCMutexLocker mu(SystemDictionary_lock);
2955 
2956   // Verify dictionary
2957   ClassLoaderDataGraph::verify_dictionary();
2958 
2959   placeholders()->verify();
2960 
2961   // Verify constraint table
2962   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2963   constraints()->verify(placeholders());
2964 
2965   _pd_cache_table->verify();
2966 }
2967 
2968 void SystemDictionary::dump(outputStream *st, bool verbose) {
2969   assert_locked_or_safepoint(SystemDictionary_lock);
2970   if (verbose) {
2971     print_on(st);
2972   } else {
2973     if (shared_dictionary() != NULL) {
2974       shared_dictionary()->print_table_statistics(st, "Shared Dictionary");
2975     }
2976     ClassLoaderDataGraph::print_dictionary_statistics(st);
2977     placeholders()->print_table_statistics(st, "Placeholder Table");
2978     constraints()->print_table_statistics(st, "LoaderConstraints Table");
2979     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
2980   }
2981 }
2982 
2983 // Utility for dumping dictionaries.
2984 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2985                                  DCmdWithParser(output, heap),
2986   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2987            "BOOLEAN", false, "false") {
2988   _dcmdparser.add_dcmd_option(&_verbose);
2989 }
2990 
2991 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2992   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2993                          _verbose.value());
2994   VMThread::execute(&dumper);
2995 }
2996 
2997 int SystemDictionaryDCmd::num_arguments() {
2998   ResourceMark rm;
2999   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
3000   if (dcmd != NULL) {
3001     DCmdMark mark(dcmd);
3002     return dcmd->_dcmdparser.num_arguments();
3003   } else {
3004     return 0;
3005   }
3006 }
3007 
3008 class CombineDictionariesClosure : public CLDClosure {
3009   private:
3010     Dictionary* _master_dictionary;
3011   public:
3012     CombineDictionariesClosure(Dictionary* master_dictionary) :
3013       _master_dictionary(master_dictionary) {}
3014     void do_cld(ClassLoaderData* cld) {
3015       ResourceMark rm;
3016       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
3017         for (int i = 0; i < cld->dictionary()->table_size(); ++i) {
3018           Dictionary* curr_dictionary = cld->dictionary();
3019           DictionaryEntry* p = curr_dictionary->bucket(i);
3020           while (p != NULL) {
3021             Symbol* name = p->instance_klass()->name();
3022             unsigned int d_hash = _master_dictionary->compute_hash(name);
3023             int d_index = _master_dictionary->hash_to_index(d_hash);
3024             DictionaryEntry* next = p->next();
3025             if (p->literal()->class_loader_data() != cld) {
3026               // This is an initiating class loader entry; don't use it
3027               log_trace(cds)("Skipping initiating cl entry: %s", name->as_C_string());
3028               curr_dictionary->free_entry(p);
3029             } else {
3030               log_trace(cds)("Moved to boot dictionary: %s", name->as_C_string());
3031               curr_dictionary->unlink_entry(p);
3032               p->set_pd_set(NULL); // pd_set is runtime only information and will be reconstructed.
3033               _master_dictionary->add_entry(d_index, p);
3034             }
3035             p = next;
3036           }
3037           *curr_dictionary->bucket_addr(i) = NULL;
3038         }
3039       }
3040     }
3041 };
3042 
3043 // Combining platform and system loader dictionaries into boot loader dictionaries.
3044 // During run time, we only have one shared dictionary.
3045 void SystemDictionary::combine_shared_dictionaries() {
3046   assert(DumpSharedSpaces, "dump time only");
3047   Dictionary* master_dictionary = ClassLoaderData::the_null_class_loader_data()->dictionary();
3048   CombineDictionariesClosure cdc(master_dictionary);
3049   ClassLoaderDataGraph::cld_do(&cdc);
3050 
3051   // These tables are no longer valid or necessary. Keeping them around will
3052   // cause SystemDictionary::verify() to fail. Let's empty them.
3053   _placeholders        = new PlaceholderTable(_placeholder_table_size);
3054   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
3055 
3056   NOT_PRODUCT(SystemDictionary::verify());
3057 }
3058 
3059 // caller needs ResourceMark
3060 const char* SystemDictionary::loader_name(const oop loader) {
3061   return ((loader) == NULL ? "<bootloader>" :
3062           InstanceKlass::cast((loader)->klass())->name()->as_C_string());
3063 }
3064 
3065 // caller needs ResourceMark
3066 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) {
3067   return (loader_data->class_loader() == NULL ? "<bootloader>" :
3068           SystemDictionary::loader_name(loader_data->class_loader()));
3069 }