1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "aot/aotLoader.hpp"
  28 #include "classfile/classFileParser.hpp"
  29 #include "classfile/classFileStream.hpp"
  30 #include "classfile/classLoader.hpp"
  31 #include "classfile/classLoaderData.inline.hpp"
  32 #include "classfile/classLoaderExt.hpp"
  33 #include "classfile/dictionary.hpp"
  34 #include "classfile/javaClasses.inline.hpp"
  35 #include "classfile/klassFactory.hpp"
  36 #include "classfile/loaderConstraints.hpp"
  37 #include "classfile/packageEntry.hpp"
  38 #include "classfile/placeholders.hpp"
  39 #include "classfile/protectionDomainCache.hpp"
  40 #include "classfile/resolutionErrors.hpp"
  41 #include "classfile/stringTable.hpp"
  42 #include "classfile/systemDictionary.hpp"
  43 #include "classfile/vmSymbols.hpp"
  44 #include "code/codeCache.hpp"
  45 #include "compiler/compileBroker.hpp"
  46 #include "gc/shared/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/access.inline.hpp"
  57 #include "oops/instanceKlass.hpp"
  58 #include "oops/instanceRefKlass.hpp"
  59 #include "oops/klass.inline.hpp"
  60 #include "oops/method.inline.hpp"
  61 #include "oops/methodData.hpp"
  62 #include "oops/objArrayKlass.hpp"
  63 #include "oops/objArrayOop.inline.hpp"
  64 #include "oops/oop.inline.hpp"
  65 #include "oops/symbol.hpp"
  66 #include "oops/typeArrayKlass.hpp"
  67 #include "prims/jvmtiEnvBase.hpp"
  68 #include "prims/resolvedMethodTable.hpp"
  69 #include "prims/methodHandles.hpp"
  70 #include "runtime/arguments.hpp"
  71 #include "runtime/arguments_ext.hpp"
  72 #include "runtime/biasedLocking.hpp"
  73 #include "runtime/fieldType.hpp"
  74 #include "runtime/handles.inline.hpp"
  75 #include "runtime/java.hpp"
  76 #include "runtime/javaCalls.hpp"
  77 #include "runtime/mutexLocker.hpp"
  78 #include "runtime/orderAccess.inline.hpp"
  79 #include "runtime/signature.hpp"
  80 #include "services/classLoadingService.hpp"
  81 #include "services/diagnosticCommand.hpp"
  82 #include "services/threadService.hpp"
  83 #include "trace/tracing.hpp"
  84 #include "utilities/macros.hpp"
  85 #if INCLUDE_CDS
  86 #include "classfile/sharedClassUtil.hpp"
  87 #include "classfile/systemDictionaryShared.hpp"
  88 #endif
  89 #if INCLUDE_JVMCI
  90 #include "jvmci/jvmciRuntime.hpp"
  91 #endif
  92 
  93 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  94 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;
  95 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  96 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  97 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
  98 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
  99 
 100 int         SystemDictionary::_number_of_modifications = 0;
 101 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 102 
 103 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 104                                                           =  { NULL /*, NULL...*/ };
 105 
 106 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 107 
 108 oop         SystemDictionary::_java_system_loader         =  NULL;
 109 oop         SystemDictionary::_java_platform_loader       =  NULL;
 110 
 111 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 112 
 113 // lazily initialized klass variables
 114 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
 115 
 116 // Default ProtectionDomainCacheSize value
 117 
 118 const int defaultProtectionDomainCacheSize = 1009;
 119 
 120 
 121 // ----------------------------------------------------------------------------
 122 // Java-level SystemLoader and PlatformLoader
 123 
 124 oop SystemDictionary::java_system_loader() {
 125   return _java_system_loader;
 126 }
 127 
 128 oop SystemDictionary::java_platform_loader() {
 129   return _java_platform_loader;
 130 }
 131 
 132 void SystemDictionary::compute_java_loaders(TRAPS) {
 133   JavaValue result(T_OBJECT);
 134   InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
 135   JavaCalls::call_static(&result,
 136                          class_loader_klass,
 137                          vmSymbols::getSystemClassLoader_name(),
 138                          vmSymbols::void_classloader_signature(),
 139                          CHECK);
 140 
 141   _java_system_loader = (oop)result.get_jobject();
 142 
 143   JavaCalls::call_static(&result,
 144                          class_loader_klass,
 145                          vmSymbols::getPlatformClassLoader_name(),
 146                          vmSymbols::void_classloader_signature(),
 147                          CHECK);
 148 
 149   _java_platform_loader = (oop)result.get_jobject();
 150 
 151   CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
 152 }
 153 
 154 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
 155   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 156   return ClassLoaderDataGraph::find_or_create(class_loader);
 157 }
 158 
 159 // ----------------------------------------------------------------------------
 160 // Parallel class loading check
 161 
 162 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 163   if (class_loader.is_null()) return true;
 164   if (AlwaysLockClassLoader) return false;
 165   return java_lang_ClassLoader::parallelCapable(class_loader());
 166 }
 167 // ----------------------------------------------------------------------------
 168 // ParallelDefineClass flag does not apply to bootclass loader
 169 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 170    if (class_loader.is_null()) return false;
 171    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 172      return true;
 173    }
 174    return false;
 175 }
 176 
 177 // Returns true if the passed class loader is the builtin application class loader
 178 // or a custom system class loader. A customer system class loader can be
 179 // specified via -Djava.system.class.loader.
 180 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 181   if (class_loader == NULL) {
 182     return false;
 183   }
 184   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 185        class_loader == _java_system_loader);
 186 }
 187 
 188 // Returns true if the passed class loader is the platform class loader.
 189 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 190   if (class_loader == NULL) {
 191     return false;
 192   }
 193   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 194 }
 195 
 196 // ----------------------------------------------------------------------------
 197 // Resolving of classes
 198 
 199 // Forwards to resolve_or_null
 200 
 201 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 202   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 203   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 204     // can return a null klass
 205     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 206   }
 207   return klass;
 208 }
 209 
 210 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 211                                                      bool throw_error,
 212                                                      Klass* klass, TRAPS) {
 213   if (HAS_PENDING_EXCEPTION) {
 214     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 215     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 216     // and if so convert it to a NoClassDefFoundError
 217     // And chain the original ClassNotFoundException
 218     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 219       ResourceMark rm(THREAD);
 220       assert(klass == NULL, "Should not have result with exception pending");
 221       Handle e(THREAD, PENDING_EXCEPTION);
 222       CLEAR_PENDING_EXCEPTION;
 223       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 224     } else {
 225       return NULL;
 226     }
 227   }
 228   // Class not found, throw appropriate error or exception depending on value of throw_error
 229   if (klass == NULL) {
 230     ResourceMark rm(THREAD);
 231     if (throw_error) {
 232       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 233     } else {
 234       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 235     }
 236   }
 237   return klass;
 238 }
 239 
 240 
 241 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 242                                            bool throw_error, TRAPS)
 243 {
 244   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 245 }
 246 
 247 
 248 // Forwards to resolve_instance_class_or_null
 249 
 250 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 251   assert(THREAD->can_call_java(),
 252          "can not load classes with compiler thread: class=%s, classloader=%s",
 253          class_name->as_C_string(),
 254          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 255   if (FieldType::is_array(class_name)) {
 256     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 257   } else if (FieldType::is_obj(class_name)) {
 258     ResourceMark rm(THREAD);
 259     // Ignore wrapping L and ;.
 260     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 261                                    class_name->utf8_length() - 2, CHECK_NULL);
 262     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 263   } else {
 264     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 265   }
 266 }
 267 
 268 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 269   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 270 }
 271 
 272 // Forwards to resolve_instance_class_or_null
 273 
 274 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 275                                                      Handle class_loader,
 276                                                      Handle protection_domain,
 277                                                      TRAPS) {
 278   assert(FieldType::is_array(class_name), "must be array");
 279   Klass* k = NULL;
 280   FieldArrayInfo fd;
 281   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 282   // of this call
 283   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 284   if (t == T_OBJECT) {
 285     // naked oop "k" is OK here -- we assign back into it
 286     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 287                                                          class_loader,
 288                                                          protection_domain,
 289                                                          CHECK_NULL);
 290     if (k != NULL) {
 291       k = k->array_klass(fd.dimension(), CHECK_NULL);
 292     }
 293   } else {
 294     k = Universe::typeArrayKlassObj(t);
 295     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 296   }
 297   return k;
 298 }
 299 
 300 
 301 // Must be called for any super-class or super-interface resolution
 302 // during class definition to allow class circularity checking
 303 // super-interface callers:
 304 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 305 // super-class callers:
 306 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 307 //   load_shared_class - while loading a class from shared archive
 308 //   resolve_instance_class_or_null:
 309 //     via: handle_parallel_super_load
 310 //      when resolving a class that has an existing placeholder with
 311 //      a saved superclass [i.e. a defineClass is currently in progress]
 312 //      if another thread is trying to resolve the class, it must do
 313 //      super-class checks on its own thread to catch class circularity
 314 // This last call is critical in class circularity checking for cases
 315 // where classloading is delegated to different threads and the
 316 // classloader lock is released.
 317 // Take the case: Base->Super->Base
 318 //   1. If thread T1 tries to do a defineClass of class Base
 319 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 320 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 321 //    so it tries to load Super
 322 //   3. If we load the class internally, or user classloader uses same thread
 323 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 324 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 325 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 326 //      3.4 calls resolve_super_or_fail Base
 327 //      3.5 finds T1,Base -> throws class circularity
 328 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 329 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 330 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 331 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 332 //      4.4 finds T2, Super -> throws class circularity
 333 // Must be called, even if superclass is null, since this is
 334 // where the placeholder entry is created which claims this
 335 // thread is loading this class/classloader.
 336 // Be careful when modifying this code: once you have run
 337 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 338 // you need to find_and_remove it before returning.
 339 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 340 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 341                                                  Symbol* class_name,
 342                                                  Handle class_loader,
 343                                                  Handle protection_domain,
 344                                                  bool is_superclass,
 345                                                  TRAPS) {
 346 #if INCLUDE_CDS
 347   if (DumpSharedSpaces) {
 348     // Special processing for CDS dump time.
 349     Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 350         class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 351     if (k) {
 352       return k;
 353     }
 354   }
 355 #endif // INCLUDE_CDS
 356 
 357   // Double-check, if child class is already loaded, just return super-class,interface
 358   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 359   // dictionary.
 360   // Make sure there's a placeholder for the *child* before resolving.
 361   // Used as a claim that this thread is currently loading superclass/classloader
 362   // Used here for ClassCircularity checks and also for heap verification
 363   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 364   // Must check ClassCircularity before checking if super class is already loaded.
 365   //
 366   // We might not already have a placeholder if this child_name was
 367   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 368   // the name of the class might not be known until the stream is actually
 369   // parsed.
 370   // Bugs 4643874, 4715493
 371 
 372   ClassLoaderData* loader_data = class_loader_data(class_loader);
 373   Dictionary* dictionary = loader_data->dictionary();
 374   unsigned int d_hash = dictionary->compute_hash(child_name);
 375   unsigned int p_hash = placeholders()->compute_hash(child_name);
 376   int p_index = placeholders()->hash_to_index(p_hash);
 377   // can't throw error holding a lock
 378   bool child_already_loaded = false;
 379   bool throw_circularity_error = false;
 380   {
 381     MutexLocker mu(SystemDictionary_lock, THREAD);
 382     Klass* childk = find_class(d_hash, child_name, dictionary);
 383     Klass* quicksuperk;
 384     // to support // loading: if child done loading, just return superclass
 385     // if class_name, & class_loader don't match:
 386     // if initial define, SD update will give LinkageError
 387     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 388     // so we don't throw an exception here.
 389     // see: nsk redefclass014 & java.lang.instrument Instrument032
 390     if ((childk != NULL ) && (is_superclass) &&
 391        ((quicksuperk = childk->super()) != NULL) &&
 392 
 393          ((quicksuperk->name() == class_name) &&
 394             (quicksuperk->class_loader()  == class_loader()))) {
 395            return quicksuperk;
 396     } else {
 397       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 398       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 399           throw_circularity_error = true;
 400       }
 401     }
 402     if (!throw_circularity_error) {
 403       // Be careful not to exit resolve_super
 404       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 405     }
 406   }
 407   if (throw_circularity_error) {
 408       ResourceMark rm(THREAD);
 409       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 410   }
 411 
 412 // java.lang.Object should have been found above
 413   assert(class_name != NULL, "null super class for resolving");
 414   // Resolve the super class or interface, check results on return
 415   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 416                                                     class_loader,
 417                                                     protection_domain,
 418                                                     THREAD);
 419 
 420   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 421   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 422   // or error. GC used to walk the placeholder table as strong roots.
 423   // The instanceKlass is kept alive because the class loader is on the stack,
 424   // which keeps the loader_data alive, as well as all instanceKlasses in
 425   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 426   {
 427     MutexLocker mu(SystemDictionary_lock, THREAD);
 428     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 429     SystemDictionary_lock->notify_all();
 430   }
 431   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 432     // can null superk
 433     superk = handle_resolution_exception(class_name, true, superk, THREAD);
 434   }
 435 
 436   return superk;
 437 }
 438 
 439 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 440                                                   Handle class_loader,
 441                                                   Handle protection_domain,
 442                                                   TRAPS) {
 443   if(!has_checkPackageAccess()) return;
 444 
 445   // Now we have to call back to java to check if the initating class has access
 446   JavaValue result(T_VOID);
 447   LogTarget(Debug, protectiondomain) lt;
 448   if (lt.is_enabled()) {
 449     ResourceMark rm;
 450     // Print out trace information
 451     LogStream ls(lt);
 452     ls.print_cr("Checking package access");
 453     ls.print("class loader: "); class_loader()->print_value_on(&ls);
 454     ls.print(" protection domain: "); protection_domain()->print_value_on(&ls);
 455     ls.print(" loading: "); klass->print_value_on(&ls);
 456     ls.cr();
 457   }
 458 
 459   // This handle and the class_loader handle passed in keeps this class from
 460   // being unloaded through several GC points.
 461   // The class_loader handle passed in is the initiating loader.
 462   Handle mirror(THREAD, klass->java_mirror());
 463 
 464   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 465   JavaCalls::call_special(&result,
 466                          class_loader,
 467                          system_loader,
 468                          vmSymbols::checkPackageAccess_name(),
 469                          vmSymbols::class_protectiondomain_signature(),
 470                          mirror,
 471                          protection_domain,
 472                          THREAD);
 473 
 474   if (HAS_PENDING_EXCEPTION) {
 475     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 476   } else {
 477    log_debug(protectiondomain)("granted");
 478   }
 479 
 480   if (HAS_PENDING_EXCEPTION) return;
 481 
 482   // If no exception has been thrown, we have validated the protection domain
 483   // Insert the protection domain of the initiating class into the set.
 484   {
 485     ClassLoaderData* loader_data = class_loader_data(class_loader);
 486     Dictionary* dictionary = loader_data->dictionary();
 487 
 488     Symbol*  kn = klass->name();
 489     unsigned int d_hash = dictionary->compute_hash(kn);
 490 
 491     MutexLocker mu(SystemDictionary_lock, THREAD);
 492     int d_index = dictionary->hash_to_index(d_hash);
 493     dictionary->add_protection_domain(d_index, d_hash, klass,
 494                                       protection_domain, THREAD);
 495   }
 496 }
 497 
 498 // We only get here if this thread finds that another thread
 499 // has already claimed the placeholder token for the current operation,
 500 // but that other thread either never owned or gave up the
 501 // object lock
 502 // Waits on SystemDictionary_lock to indicate placeholder table updated
 503 // On return, caller must recheck placeholder table state
 504 //
 505 // We only get here if
 506 //  1) custom classLoader, i.e. not bootstrap classloader
 507 //  2) custom classLoader has broken the class loader objectLock
 508 //     so another thread got here in parallel
 509 //
 510 // lockObject must be held.
 511 // Complicated dance due to lock ordering:
 512 // Must first release the classloader object lock to
 513 // allow initial definer to complete the class definition
 514 // and to avoid deadlock
 515 // Reclaim classloader lock object with same original recursion count
 516 // Must release SystemDictionary_lock after notify, since
 517 // class loader lock must be claimed before SystemDictionary_lock
 518 // to prevent deadlocks
 519 //
 520 // The notify allows applications that did an untimed wait() on
 521 // the classloader object lock to not hang.
 522 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 523   assert_lock_strong(SystemDictionary_lock);
 524 
 525   bool calledholdinglock
 526       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 527   assert(calledholdinglock,"must hold lock for notify");
 528   assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 529   ObjectSynchronizer::notifyall(lockObject, THREAD);
 530   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 531   SystemDictionary_lock->wait();
 532   SystemDictionary_lock->unlock();
 533   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 534   SystemDictionary_lock->lock();
 535 }
 536 
 537 // If the class in is in the placeholder table, class loading is in progress
 538 // For cases where the application changes threads to load classes, it
 539 // is critical to ClassCircularity detection that we try loading
 540 // the superclass on the same thread internally, so we do parallel
 541 // super class loading here.
 542 // This also is critical in cases where the original thread gets stalled
 543 // even in non-circularity situations.
 544 // Note: must call resolve_super_or_fail even if null super -
 545 // to force placeholder entry creation for this class for circularity detection
 546 // Caller must check for pending exception
 547 // Returns non-null Klass* if other thread has completed load
 548 // and we are done,
 549 // If return null Klass* and no pending exception, the caller must load the class
 550 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 551     Symbol* name, Symbol* superclassname, Handle class_loader,
 552     Handle protection_domain, Handle lockObject, TRAPS) {
 553 
 554   ClassLoaderData* loader_data = class_loader_data(class_loader);
 555   Dictionary* dictionary = loader_data->dictionary();
 556   unsigned int d_hash = dictionary->compute_hash(name);
 557   unsigned int p_hash = placeholders()->compute_hash(name);
 558   int p_index = placeholders()->hash_to_index(p_hash);
 559 
 560   // superk is not used, resolve_super called for circularity check only
 561   // This code is reached in two situations. One if this thread
 562   // is loading the same class twice (e.g. ClassCircularity, or
 563   // java.lang.instrument).
 564   // The second is if another thread started the resolve_super first
 565   // and has not yet finished.
 566   // In both cases the original caller will clean up the placeholder
 567   // entry on error.
 568   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 569                                                           superclassname,
 570                                                           class_loader,
 571                                                           protection_domain,
 572                                                           true,
 573                                                           CHECK_NULL);
 574 
 575   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 576   // Serial class loaders and bootstrap classloader do wait for superclass loads
 577  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 578     MutexLocker mu(SystemDictionary_lock, THREAD);
 579     // Check if classloading completed while we were loading superclass or waiting
 580     return find_class(d_hash, name, dictionary);
 581   }
 582 
 583   // must loop to both handle other placeholder updates
 584   // and spurious notifications
 585   bool super_load_in_progress = true;
 586   PlaceholderEntry* placeholder;
 587   while (super_load_in_progress) {
 588     MutexLocker mu(SystemDictionary_lock, THREAD);
 589     // Check if classloading completed while we were loading superclass or waiting
 590     InstanceKlass* check = find_class(d_hash, name, dictionary);
 591     if (check != NULL) {
 592       // Klass is already loaded, so just return it
 593       return check;
 594     } else {
 595       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 596       if (placeholder && placeholder->super_load_in_progress() ){
 597         // We only get here if the application has released the
 598         // classloader lock when another thread was in the middle of loading a
 599         // superclass/superinterface for this class, and now
 600         // this thread is also trying to load this class.
 601         // To minimize surprises, the first thread that started to
 602         // load a class should be the one to complete the loading
 603         // with the classfile it initially expected.
 604         // This logic has the current thread wait once it has done
 605         // all the superclass/superinterface loading it can, until
 606         // the original thread completes the class loading or fails
 607         // If it completes we will use the resulting InstanceKlass
 608         // which we will find below in the systemDictionary.
 609         // We also get here for parallel bootstrap classloader
 610         if (class_loader.is_null()) {
 611           SystemDictionary_lock->wait();
 612         } else {
 613           double_lock_wait(lockObject, THREAD);
 614         }
 615       } else {
 616         // If not in SD and not in PH, other thread's load must have failed
 617         super_load_in_progress = false;
 618       }
 619     }
 620   }
 621   return NULL;
 622 }
 623 
 624 static void post_class_load_event(EventClassLoad* event,
 625                                   const InstanceKlass* k,
 626                                   const ClassLoaderData* init_cld) {
 627 #if INCLUDE_TRACE
 628   assert(event != NULL, "invariant");
 629   assert(k != NULL, "invariant");
 630   if (event->should_commit()) {
 631     event->set_loadedClass(k);
 632     event->set_definingClassLoader(k->class_loader_data());
 633     event->set_initiatingClassLoader(init_cld);
 634     event->commit();
 635   }
 636 #endif // INCLUDE_TRACE
 637 }
 638 
 639 static void class_define_event(InstanceKlass* k,
 640                                const ClassLoaderData* def_cld) {
 641 #if INCLUDE_TRACE
 642   EventClassDefine event;
 643   if (event.should_commit()) {
 644     event.set_definedClass(k);
 645     event.set_definingClassLoader(def_cld);
 646     event.commit();
 647   }
 648 #endif // INCLUDE_TRACE
 649 }
 650 
 651 // Be careful when modifying this code: once you have run
 652 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 653 // you need to find_and_remove it before returning.
 654 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 655 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 656                                                         Handle class_loader,
 657                                                         Handle protection_domain,
 658                                                         TRAPS) {
 659   assert(name != NULL && !FieldType::is_array(name) &&
 660          !FieldType::is_obj(name), "invalid class name");
 661 
 662   EventClassLoad class_load_start_event;
 663 
 664   HandleMark hm(THREAD);
 665 
 666   // Fix for 4474172; see evaluation for more details
 667   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 668   ClassLoaderData* loader_data = register_loader(class_loader);
 669   Dictionary* dictionary = loader_data->dictionary();
 670   unsigned int d_hash = dictionary->compute_hash(name);
 671 
 672   // Do lookup to see if class already exist and the protection domain
 673   // has the right access
 674   // This call uses find which checks protection domain already matches
 675   // All subsequent calls use find_class, and set has_loaded_class so that
 676   // before we return a result we call out to java to check for valid protection domain
 677   // to allow returning the Klass* and add it to the pd_set if it is valid
 678   {
 679     Klass* probe = dictionary->find(d_hash, name, protection_domain);
 680     if (probe != NULL) return probe;
 681   }
 682 
 683   // Non-bootstrap class loaders will call out to class loader and
 684   // define via jvm/jni_DefineClass which will acquire the
 685   // class loader object lock to protect against multiple threads
 686   // defining the class in parallel by accident.
 687   // This lock must be acquired here so the waiter will find
 688   // any successful result in the SystemDictionary and not attempt
 689   // the define.
 690   // ParallelCapable Classloaders and the bootstrap classloader
 691   // do not acquire lock here.
 692   bool DoObjectLock = true;
 693   if (is_parallelCapable(class_loader)) {
 694     DoObjectLock = false;
 695   }
 696 
 697   unsigned int p_hash = placeholders()->compute_hash(name);
 698   int p_index = placeholders()->hash_to_index(p_hash);
 699 
 700   // Class is not in SystemDictionary so we have to do loading.
 701   // Make sure we are synchronized on the class loader before we proceed
 702   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 703   check_loader_lock_contention(lockObject, THREAD);
 704   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 705 
 706   // Check again (after locking) if class already exist in SystemDictionary
 707   bool class_has_been_loaded   = false;
 708   bool super_load_in_progress  = false;
 709   bool havesupername = false;
 710   InstanceKlass* k = NULL;
 711   PlaceholderEntry* placeholder;
 712   Symbol* superclassname = NULL;
 713 
 714   {
 715     MutexLocker mu(SystemDictionary_lock, THREAD);
 716     InstanceKlass* check = find_class(d_hash, name, dictionary);
 717     if (check != NULL) {
 718       // Klass is already loaded, so just return it
 719       class_has_been_loaded = true;
 720       k = check;
 721     } else {
 722       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 723       if (placeholder && placeholder->super_load_in_progress()) {
 724          super_load_in_progress = true;
 725          if (placeholder->havesupername() == true) {
 726            superclassname = placeholder->supername();
 727            havesupername = true;
 728          }
 729       }
 730     }
 731   }
 732 
 733   // If the class is in the placeholder table, class loading is in progress
 734   if (super_load_in_progress && havesupername==true) {
 735     k = handle_parallel_super_load(name,
 736                                    superclassname,
 737                                    class_loader,
 738                                    protection_domain,
 739                                    lockObject, THREAD);
 740     if (HAS_PENDING_EXCEPTION) {
 741       return NULL;
 742     }
 743     if (k != NULL) {
 744       class_has_been_loaded = true;
 745     }
 746   }
 747 
 748   bool throw_circularity_error = false;
 749   if (!class_has_been_loaded) {
 750     bool load_instance_added = false;
 751 
 752     // add placeholder entry to record loading instance class
 753     // Five cases:
 754     // All cases need to prevent modifying bootclasssearchpath
 755     // in parallel with a classload of same classname
 756     // Redefineclasses uses existence of the placeholder for the duration
 757     // of the class load to prevent concurrent redefinition of not completely
 758     // defined classes.
 759     // case 1. traditional classloaders that rely on the classloader object lock
 760     //   - no other need for LOAD_INSTANCE
 761     // case 2. traditional classloaders that break the classloader object lock
 762     //    as a deadlock workaround. Detection of this case requires that
 763     //    this check is done while holding the classloader object lock,
 764     //    and that lock is still held when calling classloader's loadClass.
 765     //    For these classloaders, we ensure that the first requestor
 766     //    completes the load and other requestors wait for completion.
 767     // case 3. Bootstrap classloader - don't own objectLocker
 768     //    This classloader supports parallelism at the classloader level,
 769     //    but only allows a single load of a class/classloader pair.
 770     //    No performance benefit and no deadlock issues.
 771     // case 4. parallelCapable user level classloaders - without objectLocker
 772     //    Allow parallel classloading of a class/classloader pair
 773 
 774     {
 775       MutexLocker mu(SystemDictionary_lock, THREAD);
 776       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 777         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 778         if (oldprobe) {
 779           // only need check_seen_thread once, not on each loop
 780           // 6341374 java/lang/Instrument with -Xcomp
 781           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 782             throw_circularity_error = true;
 783           } else {
 784             // case 1: traditional: should never see load_in_progress.
 785             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 786 
 787               // case 3: bootstrap classloader: prevent futile classloading,
 788               // wait on first requestor
 789               if (class_loader.is_null()) {
 790                 SystemDictionary_lock->wait();
 791               } else {
 792               // case 2: traditional with broken classloader lock. wait on first
 793               // requestor.
 794                 double_lock_wait(lockObject, THREAD);
 795               }
 796               // Check if classloading completed while we were waiting
 797               InstanceKlass* check = find_class(d_hash, name, dictionary);
 798               if (check != NULL) {
 799                 // Klass is already loaded, so just return it
 800                 k = check;
 801                 class_has_been_loaded = true;
 802               }
 803               // check if other thread failed to load and cleaned up
 804               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 805             }
 806           }
 807         }
 808       }
 809       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 810       // case 4: parallelCapable: allow competing threads to try
 811       // LOAD_INSTANCE in parallel
 812 
 813       if (!throw_circularity_error && !class_has_been_loaded) {
 814         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 815         load_instance_added = true;
 816         // For class loaders that do not acquire the classloader object lock,
 817         // if they did not catch another thread holding LOAD_INSTANCE,
 818         // need a check analogous to the acquire ObjectLocker/find_class
 819         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 820         // one final check if the load has already completed
 821         // class loaders holding the ObjectLock shouldn't find the class here
 822         InstanceKlass* check = find_class(d_hash, name, dictionary);
 823         if (check != NULL) {
 824         // Klass is already loaded, so return it after checking/adding protection domain
 825           k = check;
 826           class_has_been_loaded = true;
 827         }
 828       }
 829     }
 830 
 831     // must throw error outside of owning lock
 832     if (throw_circularity_error) {
 833       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 834       ResourceMark rm(THREAD);
 835       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 836     }
 837 
 838     if (!class_has_been_loaded) {
 839 
 840       // Do actual loading
 841       k = load_instance_class(name, class_loader, THREAD);
 842 
 843       // If everything was OK (no exceptions, no null return value), and
 844       // class_loader is NOT the defining loader, do a little more bookkeeping.
 845       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 846         k->class_loader() != class_loader()) {
 847 
 848         check_constraints(d_hash, k, class_loader, false, THREAD);
 849 
 850         // Need to check for a PENDING_EXCEPTION again; check_constraints
 851         // can throw and doesn't use the CHECK macro.
 852         if (!HAS_PENDING_EXCEPTION) {
 853           { // Grabbing the Compile_lock prevents systemDictionary updates
 854             // during compilations.
 855             MutexLocker mu(Compile_lock, THREAD);
 856             update_dictionary(d_hash, p_index, p_hash,
 857               k, class_loader, THREAD);
 858           }
 859 
 860           if (JvmtiExport::should_post_class_load()) {
 861             Thread *thread = THREAD;
 862             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 863             JvmtiExport::post_class_load((JavaThread *) thread, k);
 864           }
 865         }
 866       }
 867     } // load_instance_class
 868 
 869     if (load_instance_added == true) {
 870       // clean up placeholder entries for LOAD_INSTANCE success or error
 871       // This brackets the SystemDictionary updates for both defining
 872       // and initiating loaders
 873       MutexLocker mu(SystemDictionary_lock, THREAD);
 874       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 875       SystemDictionary_lock->notify_all();
 876     }
 877   }
 878 
 879   if (HAS_PENDING_EXCEPTION || k == NULL) {
 880     return NULL;
 881   }
 882 
 883   post_class_load_event(&class_load_start_event, k, loader_data);
 884 
 885 #ifdef ASSERT
 886   {
 887     ClassLoaderData* loader_data = k->class_loader_data();
 888     MutexLocker mu(SystemDictionary_lock, THREAD);
 889     Klass* kk = find_class(name, loader_data);
 890     assert(kk == k, "should be present in dictionary");
 891   }
 892 #endif
 893 
 894   // return if the protection domain in NULL
 895   if (protection_domain() == NULL) return k;
 896 
 897   // Check the protection domain has the right access
 898   if (dictionary->is_valid_protection_domain(d_hash, name,
 899                                              protection_domain)) {
 900     return k;
 901   }
 902 
 903   // Verify protection domain. If it fails an exception is thrown
 904   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 905 
 906   return k;
 907 }
 908 
 909 
 910 // This routine does not lock the system dictionary.
 911 //
 912 // Since readers don't hold a lock, we must make sure that system
 913 // dictionary entries are only removed at a safepoint (when only one
 914 // thread is running), and are added to in a safe way (all links must
 915 // be updated in an MT-safe manner).
 916 //
 917 // Callers should be aware that an entry could be added just after
 918 // _dictionary->bucket(index) is read here, so the caller will not see
 919 // the new entry.
 920 
 921 Klass* SystemDictionary::find(Symbol* class_name,
 922                               Handle class_loader,
 923                               Handle protection_domain,
 924                               TRAPS) {
 925 
 926   // The result of this call should be consistent with the result
 927   // of the call to resolve_instance_class_or_null().
 928   // See evaluation 6790209 and 4474172 for more details.
 929   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 930   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 931 
 932   if (loader_data == NULL) {
 933     // If the ClassLoaderData has not been setup,
 934     // then the class loader has no entries in the dictionary.
 935     return NULL;
 936   }
 937 
 938   Dictionary* dictionary = loader_data->dictionary();
 939   unsigned int d_hash = dictionary->compute_hash(class_name);
 940   return dictionary->find(d_hash, class_name,
 941                           protection_domain);
 942 }
 943 
 944 
 945 // Look for a loaded instance or array klass by name.  Do not do any loading.
 946 // return NULL in case of error.
 947 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 948                                                       Handle class_loader,
 949                                                       Handle protection_domain,
 950                                                       TRAPS) {
 951   Klass* k = NULL;
 952   assert(class_name != NULL, "class name must be non NULL");
 953 
 954   if (FieldType::is_array(class_name)) {
 955     // The name refers to an array.  Parse the name.
 956     // dimension and object_key in FieldArrayInfo are assigned as a
 957     // side-effect of this call
 958     FieldArrayInfo fd;
 959     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 960     if (t != T_OBJECT) {
 961       k = Universe::typeArrayKlassObj(t);
 962     } else {
 963       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 964     }
 965     if (k != NULL) {
 966       k = k->array_klass_or_null(fd.dimension());
 967     }
 968   } else {
 969     k = find(class_name, class_loader, protection_domain, THREAD);
 970   }
 971   return k;
 972 }
 973 
 974 // Note: this method is much like resolve_from_stream, but
 975 // does not publish the classes via the SystemDictionary.
 976 // Handles unsafe_DefineAnonymousClass and redefineclasses
 977 // RedefinedClasses do not add to the class hierarchy
 978 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
 979                                               Handle class_loader,
 980                                               Handle protection_domain,
 981                                               ClassFileStream* st,
 982                                               const InstanceKlass* host_klass,
 983                                               GrowableArray<Handle>* cp_patches,
 984                                               TRAPS) {
 985 
 986   EventClassLoad class_load_start_event;
 987 
 988   ClassLoaderData* loader_data;
 989   if (host_klass != NULL) {
 990     // Create a new CLD for anonymous class, that uses the same class loader
 991     // as the host_klass
 992     guarantee(host_klass->class_loader() == class_loader(), "should be the same");
 993     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader);
 994   } else {
 995     loader_data = ClassLoaderData::class_loader_data(class_loader());
 996   }
 997 
 998   assert(st != NULL, "invariant");
 999   assert(st->need_verify(), "invariant");
1000 
1001   // Parse stream and create a klass.
1002   // Note that we do this even though this klass might
1003   // already be present in the SystemDictionary, otherwise we would not
1004   // throw potential ClassFormatErrors.
1005 
1006   InstanceKlass* k = KlassFactory::create_from_stream(st,
1007                                                       class_name,
1008                                                       loader_data,
1009                                                       protection_domain,
1010                                                       host_klass,
1011                                                       cp_patches,
1012                                                       CHECK_NULL);
1013 
1014   if (host_klass != NULL && k != NULL) {
1015     // If it's anonymous, initialize it now, since nobody else will.
1016 
1017     {
1018       MutexLocker mu_r(Compile_lock, THREAD);
1019 
1020       // Add to class hierarchy, initialize vtables, and do possible
1021       // deoptimizations.
1022       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1023 
1024       // But, do not add to dictionary.
1025 
1026       // compiled code dependencies need to be validated anyway
1027       notice_modification();
1028     }
1029 
1030     // Rewrite and patch constant pool here.
1031     k->link_class(CHECK_NULL);
1032     if (cp_patches != NULL) {
1033       k->constants()->patch_resolved_references(cp_patches);
1034     }
1035     k->eager_initialize(CHECK_NULL);
1036 
1037     // notify jvmti
1038     if (JvmtiExport::should_post_class_load()) {
1039         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1040         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1041     }
1042 
1043     post_class_load_event(&class_load_start_event, k, loader_data);
1044   }
1045   assert(host_klass != NULL || NULL == cp_patches,
1046          "cp_patches only found with host_klass");
1047 
1048   return k;
1049 }
1050 
1051 // Add a klass to the system from a stream (called by jni_DefineClass and
1052 // JVM_DefineClass).
1053 // Note: class_name can be NULL. In that case we do not know the name of
1054 // the class until we have parsed the stream.
1055 
1056 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1057                                                      Handle class_loader,
1058                                                      Handle protection_domain,
1059                                                      ClassFileStream* st,
1060                                                      TRAPS) {
1061 
1062   HandleMark hm(THREAD);
1063 
1064   // Classloaders that support parallelism, e.g. bootstrap classloader,
1065   // do not acquire lock here
1066   bool DoObjectLock = true;
1067   if (is_parallelCapable(class_loader)) {
1068     DoObjectLock = false;
1069   }
1070 
1071   ClassLoaderData* loader_data = register_loader(class_loader);
1072 
1073   // Make sure we are synchronized on the class loader before we proceed
1074   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1075   check_loader_lock_contention(lockObject, THREAD);
1076   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1077 
1078   assert(st != NULL, "invariant");
1079 
1080   // Parse the stream and create a klass.
1081   // Note that we do this even though this klass might
1082   // already be present in the SystemDictionary, otherwise we would not
1083   // throw potential ClassFormatErrors.
1084  InstanceKlass* k = NULL;
1085 
1086 #if INCLUDE_CDS
1087   if (!DumpSharedSpaces) {
1088     k = SystemDictionaryShared::lookup_from_stream(class_name,
1089                                                    class_loader,
1090                                                    protection_domain,
1091                                                    st,
1092                                                    CHECK_NULL);
1093   }
1094 #endif
1095 
1096   if (k == NULL) {
1097     if (st->buffer() == NULL) {
1098       return NULL;
1099     }
1100     k = KlassFactory::create_from_stream(st,
1101                                          class_name,
1102                                          loader_data,
1103                                          protection_domain,
1104                                          NULL, // host_klass
1105                                          NULL, // cp_patches
1106                                          CHECK_NULL);
1107   }
1108 
1109   assert(k != NULL, "no klass created");
1110   Symbol* h_name = k->name();
1111   assert(class_name == NULL || class_name == h_name, "name mismatch");
1112 
1113   // Add class just loaded
1114   // If a class loader supports parallel classloading handle parallel define requests
1115   // find_or_define_instance_class may return a different InstanceKlass
1116   if (is_parallelCapable(class_loader)) {
1117     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1118     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1119       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1120       assert(defined_k != NULL, "Should have a klass if there's no exception");
1121       loader_data->add_to_deallocate_list(k);
1122       k = defined_k;
1123     }
1124   } else {
1125     define_instance_class(k, THREAD);
1126   }
1127 
1128   // If defining the class throws an exception register 'k' for cleanup.
1129   if (HAS_PENDING_EXCEPTION) {
1130     assert(k != NULL, "Must have an instance klass here!");
1131     loader_data->add_to_deallocate_list(k);
1132     return NULL;
1133   }
1134 
1135   // Make sure we have an entry in the SystemDictionary on success
1136   debug_only( {
1137     MutexLocker mu(SystemDictionary_lock, THREAD);
1138 
1139     Klass* check = find_class(h_name, k->class_loader_data());
1140     assert(check == k, "should be present in the dictionary");
1141   } );
1142 
1143   return k;
1144 }
1145 
1146 #if INCLUDE_CDS
1147 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1148                                              int number_of_entries) {
1149   assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>),
1150          "bad shared dictionary size.");
1151   _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(),
1152                                       _shared_dictionary_size, t, number_of_entries);
1153 }
1154 
1155 
1156 // If there is a shared dictionary, then find the entry for the
1157 // given shared system class, if any.
1158 
1159 InstanceKlass* SystemDictionary::find_shared_class(Symbol* class_name) {
1160   if (shared_dictionary() != NULL) {
1161     unsigned int d_hash = shared_dictionary()->compute_hash(class_name);
1162     int d_index = shared_dictionary()->hash_to_index(d_hash);
1163 
1164     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1165   } else {
1166     return NULL;
1167   }
1168 }
1169 
1170 
1171 // Load a class from the shared spaces (found through the shared system
1172 // dictionary).  Force the superclass and all interfaces to be loaded.
1173 // Update the class definition to include sibling classes and no
1174 // subclasses (yet).  [Classes in the shared space are not part of the
1175 // object hierarchy until loaded.]
1176 
1177 InstanceKlass* SystemDictionary::load_shared_class(
1178                  Symbol* class_name, Handle class_loader, TRAPS) {
1179   InstanceKlass* ik = find_shared_class(class_name);
1180   // Make sure we only return the boot class for the NULL classloader.
1181   if (ik != NULL &&
1182       ik->is_shared_boot_class() && class_loader.is_null()) {
1183     Handle protection_domain;
1184     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1185   }
1186   return NULL;
1187 }
1188 
1189 // Check if a shared class can be loaded by the specific classloader:
1190 //
1191 // NULL classloader:
1192 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1193 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1194 //     be defined in an unnamed module.
1195 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1196                                                InstanceKlass* ik,
1197                                                Handle class_loader, TRAPS) {
1198   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1199          "Cannot use sharing if java.base is patched");
1200   ResourceMark rm;
1201   int path_index = ik->shared_classpath_index();
1202   ClassLoaderData* loader_data = class_loader_data(class_loader);
1203   if (path_index < 0) {
1204     // path_index < 0 indicates that the class is intended for a custom loader
1205     // and should not be loaded by boot/platform/app loaders
1206     if (loader_data->is_builtin_class_loader_data()) {
1207       return false;
1208     } else {
1209       return true;
1210     }
1211   }
1212   SharedClassPathEntry* ent =
1213             (SharedClassPathEntry*)FileMapInfo::shared_classpath(path_index);
1214   if (!Universe::is_module_initialized()) {
1215     assert(ent != NULL && ent->is_modules_image(),
1216            "Loading non-bootstrap classes before the module system is initialized");
1217     assert(class_loader.is_null(), "sanity");
1218     return true;
1219   }
1220   // Get the pkg_entry from the classloader
1221   TempNewSymbol pkg_name = NULL;
1222   PackageEntry* pkg_entry = NULL;
1223   ModuleEntry* mod_entry = NULL;
1224   const char* pkg_string = NULL;
1225   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1226   if (pkg_name != NULL) {
1227     pkg_string = pkg_name->as_C_string();
1228     if (loader_data != NULL) {
1229       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1230     }
1231     if (pkg_entry != NULL) {
1232       mod_entry = pkg_entry->module();
1233     }
1234   }
1235 
1236   // If the archived class is from a module that has been patched at runtime,
1237   // the class cannot be loaded from the archive.
1238   if (mod_entry != NULL && mod_entry->is_patched()) {
1239     return false;
1240   }
1241 
1242   if (class_loader.is_null()) {
1243     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1244     // The NULL classloader can load archived class originated from the
1245     // "modules" jimage and the -Xbootclasspath/a. For class from the
1246     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1247     // by the NULL classloader.
1248     if (mod_entry != NULL) {
1249       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1250       // ModuleEntry's location agrees with the archived class' origination.
1251       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1252         return true; // Module class from the "module" jimage
1253       }
1254     }
1255 
1256     // If the archived class is not from the "module" jimage, the class can be
1257     // loaded by the NULL classloader if
1258     //
1259     // 1. the class is from the unamed package
1260     // 2. or, the class is not from a module defined in the NULL classloader
1261     // 3. or, the class is from an unamed module
1262     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1263       // the class is from the -Xbootclasspath/a
1264       if (pkg_string == NULL ||
1265           pkg_entry == NULL ||
1266           pkg_entry->in_unnamed_module()) {
1267         assert(mod_entry == NULL ||
1268                mod_entry == loader_data->unnamed_module(),
1269                "the unnamed module is not defined in the classloader");
1270         return true;
1271       }
1272     }
1273     return false;
1274   } else {
1275     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1276               ik, class_loader, pkg_string, pkg_name,
1277               pkg_entry, mod_entry, CHECK_(false));
1278     return res;
1279   }
1280 }
1281 
1282 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1283                                                    Handle class_loader,
1284                                                    Handle protection_domain, TRAPS) {
1285 
1286   if (ik != NULL) {
1287     Symbol* class_name = ik->name();
1288 
1289     bool visible = is_shared_class_visible(
1290                             class_name, ik, class_loader, CHECK_NULL);
1291     if (!visible) {
1292       return NULL;
1293     }
1294 
1295     // Resolve the superclass and interfaces. They must be the same
1296     // as in dump time, because the layout of <ik> depends on
1297     // the specific layout of ik->super() and ik->local_interfaces().
1298     //
1299     // If unexpected superclass or interfaces are found, we cannot
1300     // load <ik> from the shared archive.
1301 
1302     if (ik->super() != NULL) {
1303       Symbol*  cn = ik->super()->name();
1304       Klass *s = resolve_super_or_fail(class_name, cn,
1305                                        class_loader, protection_domain, true, CHECK_NULL);
1306       if (s != ik->super()) {
1307         // The dynamically resolved super class is not the same as the one we used during dump time,
1308         // so we cannot use ik.
1309         return NULL;
1310       } else {
1311         assert(s->is_shared(), "must be");
1312       }
1313     }
1314 
1315     Array<Klass*>* interfaces = ik->local_interfaces();
1316     int num_interfaces = interfaces->length();
1317     for (int index = 0; index < num_interfaces; index++) {
1318       Klass* k = interfaces->at(index);
1319       Symbol*  name  = k->name();
1320       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1321       if (k != i) {
1322         // The dynamically resolved interface class is not the same as the one we used during dump time,
1323         // so we cannot use ik.
1324         return NULL;
1325       } else {
1326         assert(i->is_shared(), "must be");
1327       }
1328     }
1329 
1330     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1331         ik, class_name, class_loader, protection_domain, CHECK_NULL);
1332     if (new_ik != NULL) {
1333       // The class is changed by CFLH. Return the new class. The shared class is
1334       // not used.
1335       return new_ik;
1336     }
1337 
1338     // Adjust methods to recover missing data.  They need addresses for
1339     // interpreter entry points and their default native method address
1340     // must be reset.
1341 
1342     // Updating methods must be done under a lock so multiple
1343     // threads don't update these in parallel
1344     //
1345     // Shared classes are all currently loaded by either the bootstrap or
1346     // internal parallel class loaders, so this will never cause a deadlock
1347     // on a custom class loader lock.
1348 
1349     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1350     {
1351       HandleMark hm(THREAD);
1352       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1353       check_loader_lock_contention(lockObject, THREAD);
1354       ObjectLocker ol(lockObject, THREAD, true);
1355       // prohibited package check assumes all classes loaded from archive call
1356       // restore_unshareable_info which calls ik->set_package()
1357       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1358     }
1359 
1360     ik->print_class_load_logging(loader_data, NULL, NULL);
1361 
1362     // For boot loader, ensure that GetSystemPackage knows that a class in this
1363     // package was loaded.
1364     if (class_loader.is_null()) {
1365       int path_index = ik->shared_classpath_index();
1366       ResourceMark rm;
1367       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1368     }
1369 
1370     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1371       // Only dump the classes that can be stored into CDS archive
1372       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1373         ResourceMark rm(THREAD);
1374         classlist_file->print_cr("%s", ik->name()->as_C_string());
1375         classlist_file->flush();
1376       }
1377     }
1378 
1379     // notify a class loaded from shared object
1380     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1381   }
1382 
1383   ik->set_has_passed_fingerprint_check(false);
1384   if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1385     uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1386     uint64_t cds_fp = ik->get_stored_fingerprint();
1387     if (aot_fp != 0 && aot_fp == cds_fp) {
1388       // This class matches with a class saved in an AOT library
1389       ik->set_has_passed_fingerprint_check(true);
1390     } else {
1391       ResourceMark rm;
1392       log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1393     }
1394   }
1395   return ik;
1396 }
1397 
1398 void SystemDictionary::clear_invoke_method_table() {
1399   SymbolPropertyEntry* spe = NULL;
1400   for (int index = 0; index < _invoke_method_table->table_size(); index++) {
1401     SymbolPropertyEntry* p = _invoke_method_table->bucket(index);
1402     while (p != NULL) {
1403       spe = p;
1404       p = p->next();
1405       _invoke_method_table->free_entry(spe);
1406     }
1407   }
1408 }
1409 #endif // INCLUDE_CDS
1410 
1411 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1412 
1413   if (class_loader.is_null()) {
1414     ResourceMark rm;
1415     PackageEntry* pkg_entry = NULL;
1416     bool search_only_bootloader_append = false;
1417     ClassLoaderData *loader_data = class_loader_data(class_loader);
1418 
1419     // Find the package in the boot loader's package entry table.
1420     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1421     if (pkg_name != NULL) {
1422       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1423     }
1424 
1425     // Prior to attempting to load the class, enforce the boot loader's
1426     // visibility boundaries.
1427     if (!Universe::is_module_initialized()) {
1428       // During bootstrapping, prior to module initialization, any
1429       // class attempting to be loaded must be checked against the
1430       // java.base packages in the boot loader's PackageEntryTable.
1431       // No class outside of java.base is allowed to be loaded during
1432       // this bootstrapping window.
1433       if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1434         // Class is either in the unnamed package or in
1435         // a named package within the unnamed module.  Either
1436         // case is outside of java.base, do not attempt to
1437         // load the class post java.base definition.  If
1438         // java.base has not been defined, let the class load
1439         // and its package will be checked later by
1440         // ModuleEntryTable::verify_javabase_packages.
1441         if (ModuleEntryTable::javabase_defined()) {
1442           return NULL;
1443         }
1444       } else {
1445         // Check that the class' package is defined within java.base.
1446         ModuleEntry* mod_entry = pkg_entry->module();
1447         Symbol* mod_entry_name = mod_entry->name();
1448         if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1449           return NULL;
1450         }
1451       }
1452     } else {
1453       // After the module system has been initialized, check if the class'
1454       // package is in a module defined to the boot loader.
1455       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1456         // Class is either in the unnamed package, in a named package
1457         // within a module not defined to the boot loader or in a
1458         // a named package within the unnamed module.  In all cases,
1459         // limit visibility to search for the class only in the boot
1460         // loader's append path.
1461         search_only_bootloader_append = true;
1462       }
1463     }
1464 
1465     // Prior to bootstrapping's module initialization, never load a class outside
1466     // of the boot loader's module path
1467     assert(Universe::is_module_initialized() ||
1468            !search_only_bootloader_append,
1469            "Attempt to load a class outside of boot loader's module path");
1470 
1471     // Search the shared system dictionary for classes preloaded into the
1472     // shared spaces.
1473     InstanceKlass* k = NULL;
1474     {
1475 #if INCLUDE_CDS
1476       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1477       k = load_shared_class(class_name, class_loader, THREAD);
1478 #endif
1479     }
1480 
1481     if (k == NULL) {
1482       // Use VM class loader
1483       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1484       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1485     }
1486 
1487     // find_or_define_instance_class may return a different InstanceKlass
1488     if (k != NULL) {
1489       InstanceKlass* defined_k =
1490         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1491       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1492         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1493         assert(defined_k != NULL, "Should have a klass if there's no exception");
1494         loader_data->add_to_deallocate_list(k);
1495         k = defined_k;
1496       } else if (HAS_PENDING_EXCEPTION) {
1497         loader_data->add_to_deallocate_list(k);
1498         return NULL;
1499       }
1500     }
1501     return k;
1502   } else {
1503     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1504     ResourceMark rm(THREAD);
1505 
1506     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1507     JavaThread* jt = (JavaThread*) THREAD;
1508 
1509     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1510                                ClassLoader::perf_app_classload_selftime(),
1511                                ClassLoader::perf_app_classload_count(),
1512                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1513                                jt->get_thread_stat()->perf_timers_addr(),
1514                                PerfClassTraceTime::CLASS_LOAD);
1515 
1516     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1517     // Translate to external class name format, i.e., convert '/' chars to '.'
1518     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1519 
1520     JavaValue result(T_OBJECT);
1521 
1522     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1523 
1524     // Call public unsynchronized loadClass(String) directly for all class loaders.
1525     // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1526     // acquire a class-name based lock rather than the class loader object lock.
1527     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1528     JavaCalls::call_virtual(&result,
1529                             class_loader,
1530                             spec_klass,
1531                             vmSymbols::loadClass_name(),
1532                             vmSymbols::string_class_signature(),
1533                             string,
1534                             CHECK_NULL);
1535 
1536     assert(result.get_type() == T_OBJECT, "just checking");
1537     oop obj = (oop) result.get_jobject();
1538 
1539     // Primitive classes return null since forName() can not be
1540     // used to obtain any of the Class objects representing primitives or void
1541     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1542       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1543       // For user defined Java class loaders, check that the name returned is
1544       // the same as that requested.  This check is done for the bootstrap
1545       // loader when parsing the class file.
1546       if (class_name == k->name()) {
1547         return k;
1548       }
1549     }
1550     // Class is not found or has the wrong name, return NULL
1551     return NULL;
1552   }
1553 }
1554 
1555 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1556 
1557   HandleMark hm(THREAD);
1558   ClassLoaderData* loader_data = k->class_loader_data();
1559   Handle class_loader_h(THREAD, loader_data->class_loader());
1560 
1561  // for bootstrap and other parallel classloaders don't acquire lock,
1562  // use placeholder token
1563  // If a parallelCapable class loader calls define_instance_class instead of
1564  // find_or_define_instance_class to get here, we have a timing
1565  // hole with systemDictionary updates and check_constraints
1566  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1567     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1568          compute_loader_lock_object(class_loader_h, THREAD)),
1569          "define called without lock");
1570   }
1571 
1572   // Check class-loading constraints. Throw exception if violation is detected.
1573   // Grabs and releases SystemDictionary_lock
1574   // The check_constraints/find_class call and update_dictionary sequence
1575   // must be "atomic" for a specific class/classloader pair so we never
1576   // define two different instanceKlasses for that class/classloader pair.
1577   // Existing classloaders will call define_instance_class with the
1578   // classloader lock held
1579   // Parallel classloaders will call find_or_define_instance_class
1580   // which will require a token to perform the define class
1581   Symbol*  name_h = k->name();
1582   Dictionary* dictionary = loader_data->dictionary();
1583   unsigned int d_hash = dictionary->compute_hash(name_h);
1584   check_constraints(d_hash, k, class_loader_h, true, CHECK);
1585 
1586   // Register class just loaded with class loader (placed in Vector)
1587   // Note we do this before updating the dictionary, as this can
1588   // fail with an OutOfMemoryError (if it does, we will *not* put this
1589   // class in the dictionary and will not update the class hierarchy).
1590   // JVMTI FollowReferences needs to find the classes this way.
1591   if (k->class_loader() != NULL) {
1592     methodHandle m(THREAD, Universe::loader_addClass_method());
1593     JavaValue result(T_VOID);
1594     JavaCallArguments args(class_loader_h);
1595     args.push_oop(Handle(THREAD, k->java_mirror()));
1596     JavaCalls::call(&result, m, &args, CHECK);
1597   }
1598 
1599   // Add the new class. We need recompile lock during update of CHA.
1600   {
1601     unsigned int p_hash = placeholders()->compute_hash(name_h);
1602     int p_index = placeholders()->hash_to_index(p_hash);
1603 
1604     MutexLocker mu_r(Compile_lock, THREAD);
1605 
1606     // Add to class hierarchy, initialize vtables, and do possible
1607     // deoptimizations.
1608     add_to_hierarchy(k, CHECK); // No exception, but can block
1609 
1610     // Add to systemDictionary - so other classes can see it.
1611     // Grabs and releases SystemDictionary_lock
1612     update_dictionary(d_hash, p_index, p_hash,
1613                       k, class_loader_h, THREAD);
1614   }
1615   k->eager_initialize(THREAD);
1616 
1617   // notify jvmti
1618   if (JvmtiExport::should_post_class_load()) {
1619       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1620       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1621 
1622   }
1623   class_define_event(k, loader_data);
1624 }
1625 
1626 // Support parallel classloading
1627 // All parallel class loaders, including bootstrap classloader
1628 // lock a placeholder entry for this class/class_loader pair
1629 // to allow parallel defines of different classes for this class loader
1630 // With AllowParallelDefine flag==true, in case they do not synchronize around
1631 // FindLoadedClass/DefineClass, calls, we check for parallel
1632 // loading for them, wait if a defineClass is in progress
1633 // and return the initial requestor's results
1634 // This flag does not apply to the bootstrap classloader.
1635 // With AllowParallelDefine flag==false, call through to define_instance_class
1636 // which will throw LinkageError: duplicate class definition.
1637 // False is the requested default.
1638 // For better performance, the class loaders should synchronize
1639 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1640 // potentially waste time reading and parsing the bytestream.
1641 // Note: VM callers should ensure consistency of k/class_name,class_loader
1642 // Be careful when modifying this code: once you have run
1643 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1644 // you need to find_and_remove it before returning.
1645 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1646 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1647                                                                InstanceKlass* k, TRAPS) {
1648 
1649   Symbol*  name_h = k->name(); // passed in class_name may be null
1650   ClassLoaderData* loader_data = class_loader_data(class_loader);
1651   Dictionary* dictionary = loader_data->dictionary();
1652 
1653   unsigned int d_hash = dictionary->compute_hash(name_h);
1654 
1655   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1656   unsigned int p_hash = placeholders()->compute_hash(name_h);
1657   int p_index = placeholders()->hash_to_index(p_hash);
1658   PlaceholderEntry* probe;
1659 
1660   {
1661     MutexLocker mu(SystemDictionary_lock, THREAD);
1662     // First check if class already defined
1663     if (is_parallelDefine(class_loader)) {
1664       InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1665       if (check != NULL) {
1666         return check;
1667       }
1668     }
1669 
1670     // Acquire define token for this class/classloader
1671     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1672     // Wait if another thread defining in parallel
1673     // All threads wait - even those that will throw duplicate class: otherwise
1674     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1675     // if other thread has not finished updating dictionary
1676     while (probe->definer() != NULL) {
1677       SystemDictionary_lock->wait();
1678     }
1679     // Only special cases allow parallel defines and can use other thread's results
1680     // Other cases fall through, and may run into duplicate defines
1681     // caught by finding an entry in the SystemDictionary
1682     if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1683         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1684         SystemDictionary_lock->notify_all();
1685 #ifdef ASSERT
1686         InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1687         assert(check != NULL, "definer missed recording success");
1688 #endif
1689         return probe->instance_klass();
1690     } else {
1691       // This thread will define the class (even if earlier thread tried and had an error)
1692       probe->set_definer(THREAD);
1693     }
1694   }
1695 
1696   define_instance_class(k, THREAD);
1697 
1698   Handle linkage_exception = Handle(); // null handle
1699 
1700   // definer must notify any waiting threads
1701   {
1702     MutexLocker mu(SystemDictionary_lock, THREAD);
1703     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1704     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1705     if (probe != NULL) {
1706       if (HAS_PENDING_EXCEPTION) {
1707         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1708         CLEAR_PENDING_EXCEPTION;
1709       } else {
1710         probe->set_instance_klass(k);
1711       }
1712       probe->set_definer(NULL);
1713       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1714       SystemDictionary_lock->notify_all();
1715     }
1716   }
1717 
1718   // Can't throw exception while holding lock due to rank ordering
1719   if (linkage_exception() != NULL) {
1720     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1721   }
1722 
1723   return k;
1724 }
1725 
1726 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1727   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1728   if (class_loader.is_null()) {
1729     return Handle(THREAD, _system_loader_lock_obj);
1730   } else {
1731     return class_loader;
1732   }
1733 }
1734 
1735 // This method is added to check how often we have to wait to grab loader
1736 // lock. The results are being recorded in the performance counters defined in
1737 // ClassLoader::_sync_systemLoaderLockContentionRate and
1738 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1739 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1740   if (!UsePerfData) {
1741     return;
1742   }
1743 
1744   assert(!loader_lock.is_null(), "NULL lock object");
1745 
1746   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1747       == ObjectSynchronizer::owner_other) {
1748     // contention will likely happen, so increment the corresponding
1749     // contention counter.
1750     if (loader_lock() == _system_loader_lock_obj) {
1751       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1752     } else {
1753       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1754     }
1755   }
1756 }
1757 
1758 // ----------------------------------------------------------------------------
1759 // Lookup
1760 
1761 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1762                                             Symbol* class_name,
1763                                             Dictionary* dictionary) {
1764   assert_locked_or_safepoint(SystemDictionary_lock);
1765   int index = dictionary->hash_to_index(hash);
1766   return dictionary->find_class(index, hash, class_name);
1767 }
1768 
1769 
1770 // Basic find on classes in the midst of being loaded
1771 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1772                                            ClassLoaderData* loader_data) {
1773   assert_locked_or_safepoint(SystemDictionary_lock);
1774   unsigned int p_hash = placeholders()->compute_hash(class_name);
1775   int p_index = placeholders()->hash_to_index(p_hash);
1776   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1777 }
1778 
1779 
1780 // Used for assertions and verification only
1781 // Precalculating the hash and index is an optimization because there are many lookups
1782 // before adding the class.
1783 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1784   assert_locked_or_safepoint(SystemDictionary_lock);
1785   #ifndef ASSERT
1786   guarantee(VerifyBeforeGC      ||
1787             VerifyDuringGC      ||
1788             VerifyBeforeExit    ||
1789             VerifyDuringStartup ||
1790             VerifyAfterGC, "too expensive");
1791   #endif
1792 
1793   Dictionary* dictionary = loader_data->dictionary();
1794   unsigned int d_hash = dictionary->compute_hash(class_name);
1795   return find_class(d_hash, class_name, dictionary);
1796 }
1797 
1798 
1799 // ----------------------------------------------------------------------------
1800 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1801 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1802 // before a new class is used.
1803 
1804 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1805   assert(k != NULL, "just checking");
1806   assert_locked_or_safepoint(Compile_lock);
1807 
1808   // Link into hierachy. Make sure the vtables are initialized before linking into
1809   k->append_to_sibling_list();                    // add to superklass/sibling list
1810   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1811   k->set_init_state(InstanceKlass::loaded);
1812   // Now flush all code that depended on old class hierarchy.
1813   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1814   // Also, first reinitialize vtable because it may have gotten out of synch
1815   // while the new class wasn't connected to the class hierarchy.
1816   CodeCache::flush_dependents_on(k);
1817 }
1818 
1819 // ----------------------------------------------------------------------------
1820 // GC support
1821 
1822 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1823   roots_oops_do(blk, NULL);
1824 }
1825 
1826 
1827 #ifdef ASSERT
1828 class VerifySDReachableAndLiveClosure : public OopClosure {
1829 private:
1830   BoolObjectClosure* _is_alive;
1831 
1832   template <class T> void do_oop_work(T* p) {
1833     oop obj = RawAccess<>::oop_load(p);
1834     guarantee(_is_alive->do_object_b(obj), "Oop in protection domain cache table must be live");
1835   }
1836 
1837 public:
1838   VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1839 
1840   virtual void do_oop(oop* p)       { do_oop_work(p); }
1841   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1842 };
1843 #endif
1844 
1845 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1846 // Note: anonymous classes are not in the SD.
1847 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1848                                     GCTimer* gc_timer,
1849                                     bool do_cleaning) {
1850 
1851 
1852   bool unloading_occurred;
1853   {
1854     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1855 
1856     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1857     unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1858                                                             do_cleaning);
1859   }
1860 
1861   if (unloading_occurred) {
1862     GCTraceTime(Debug, gc, phases) t("Dictionary", gc_timer);
1863     constraints()->purge_loader_constraints();
1864     resolution_errors()->purge_resolution_errors();
1865   }
1866 
1867   {
1868     GCTraceTime(Debug, gc, phases) t("ProtectionDomainCacheTable", gc_timer);
1869     // Oops referenced by the protection domain cache table may get unreachable independently
1870     // of the class loader (eg. cached protection domain oops). So we need to
1871     // explicitly unlink them here.
1872     _pd_cache_table->unlink(is_alive);
1873 
1874 #ifdef ASSERT
1875     VerifySDReachableAndLiveClosure cl(is_alive);
1876     _pd_cache_table->oops_do(&cl);
1877 #endif
1878   }
1879 
1880   if (do_cleaning) {
1881     GCTraceTime(Debug, gc, phases) t("ResolvedMethodTable", gc_timer);
1882     ResolvedMethodTable::unlink(is_alive);
1883   }
1884 
1885   return unloading_occurred;
1886 }
1887 
1888 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1889   strong->do_oop(&_java_system_loader);
1890   strong->do_oop(&_java_platform_loader);
1891   strong->do_oop(&_system_loader_lock_obj);
1892   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1893 
1894   // Do strong roots marking if the closures are the same.
1895   if (strong == weak || !ClassUnloading) {
1896     // Only the protection domain oops contain references into the heap. Iterate
1897     // over all of them.
1898     _pd_cache_table->oops_do(strong);
1899   } else {
1900    if (weak != NULL) {
1901      _pd_cache_table->oops_do(weak);
1902    }
1903   }
1904 
1905   // Visit extra methods
1906   invoke_method_table()->oops_do(strong);
1907 
1908   if (weak != NULL) {
1909     ResolvedMethodTable::oops_do(weak);
1910   }
1911 }
1912 
1913 void SystemDictionary::oops_do(OopClosure* f) {
1914   f->do_oop(&_java_system_loader);
1915   f->do_oop(&_java_platform_loader);
1916   f->do_oop(&_system_loader_lock_obj);
1917   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1918 
1919   // Only the protection domain oops contain references into the heap. Iterate
1920   // over all of them.
1921   _pd_cache_table->oops_do(f);
1922 
1923   // Visit extra methods
1924   invoke_method_table()->oops_do(f);
1925 
1926   ResolvedMethodTable::oops_do(f);
1927 }
1928 
1929 // CDS: scan and relocate all classes in the system dictionary.
1930 void SystemDictionary::classes_do(MetaspaceClosure* it) {
1931   ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(it);
1932 }
1933 
1934 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1935 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1936   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1937     it->push(well_known_klass_addr((WKID)id));
1938   }
1939 }
1940 
1941 void SystemDictionary::methods_do(void f(Method*)) {
1942   // Walk methods in loaded classes
1943   ClassLoaderDataGraph::methods_do(f);
1944   // Walk method handle intrinsics
1945   invoke_method_table()->methods_do(f);
1946 }
1947 
1948 class RemoveClassesClosure : public CLDClosure {
1949   public:
1950     void do_cld(ClassLoaderData* cld) {
1951       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
1952         cld->dictionary()->remove_classes_in_error_state();
1953       }
1954     }
1955 };
1956 
1957 void SystemDictionary::remove_classes_in_error_state() {
1958   ClassLoaderData::the_null_class_loader_data()->dictionary()->remove_classes_in_error_state();
1959   RemoveClassesClosure rcc;
1960   ClassLoaderDataGraph::cld_do(&rcc);
1961 }
1962 
1963 // ----------------------------------------------------------------------------
1964 // Lazily load klasses
1965 
1966 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1967   // if multiple threads calling this function, only one thread will load
1968   // the class.  The other threads will find the loaded version once the
1969   // class is loaded.
1970   Klass* aos = _abstract_ownable_synchronizer_klass;
1971   if (aos == NULL) {
1972     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1973     // Force a fence to prevent any read before the write completes
1974     OrderAccess::fence();
1975     _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
1976   }
1977 }
1978 
1979 // ----------------------------------------------------------------------------
1980 // Initialization
1981 
1982 void SystemDictionary::initialize(TRAPS) {
1983   // Allocate arrays
1984   _placeholders        = new PlaceholderTable(_placeholder_table_size);
1985   _number_of_modifications = 0;
1986   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1987   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1988   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1989   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1990 
1991   // Allocate private object used as system class loader lock
1992   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1993   // Initialize basic classes
1994   initialize_preloaded_classes(CHECK);
1995 }
1996 
1997 // Compact table of directions on the initialization of klasses:
1998 static const short wk_init_info[] = {
1999   #define WK_KLASS_INIT_INFO(name, symbol, option) \
2000     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
2001           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
2002       | (int)SystemDictionary::option ),
2003   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
2004   #undef WK_KLASS_INIT_INFO
2005   0
2006 };
2007 
2008 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
2009   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2010   int  info = wk_init_info[id - FIRST_WKID];
2011   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
2012   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
2013   InstanceKlass** klassp = &_well_known_klasses[id];
2014 
2015   bool must_load;
2016 #if INCLUDE_JVMCI
2017   if (EnableJVMCI) {
2018     // If JVMCI is enabled we require its classes to be found.
2019     must_load = (init_opt < SystemDictionary::Opt) || (init_opt == SystemDictionary::Jvmci);
2020   } else
2021 #endif
2022   {
2023     must_load = (init_opt < SystemDictionary::Opt);
2024   }
2025 
2026   if ((*klassp) == NULL) {
2027     Klass* k;
2028     if (must_load) {
2029       k = resolve_or_fail(symbol, true, CHECK_0); // load required class
2030     } else {
2031       k = resolve_or_null(symbol,       CHECK_0); // load optional klass
2032     }
2033     (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
2034   }
2035   return ((*klassp) != NULL);
2036 }
2037 
2038 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
2039   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
2040   for (int id = (int)start_id; id < (int)limit_id; id++) {
2041     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2042     int info = wk_init_info[id - FIRST_WKID];
2043     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
2044     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
2045 
2046     initialize_wk_klass((WKID)id, opt, CHECK);
2047   }
2048 
2049   // move the starting value forward to the limit:
2050   start_id = limit_id;
2051 }
2052 
2053 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
2054   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
2055 
2056   // Create the ModuleEntry for java.base.  This call needs to be done here,
2057   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
2058   ClassLoader::classLoader_init2(CHECK);
2059 
2060   // Preload commonly used klasses
2061   WKID scan = FIRST_WKID;
2062   // first do Object, then String, Class
2063 #if INCLUDE_CDS
2064   if (UseSharedSpaces) {
2065     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
2066     // Initialize the constant pool for the Object_class
2067     Object_klass()->constants()->restore_unshareable_info(CHECK);
2068     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2069   } else
2070 #endif
2071   {
2072     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2073   }
2074 
2075   // Calculate offsets for String and Class classes since they are loaded and
2076   // can be used after this point.
2077   java_lang_String::compute_offsets();
2078   java_lang_Class::compute_offsets();
2079 
2080   // Fixup mirrors for classes loaded before java.lang.Class.
2081   // These calls iterate over the objects currently in the perm gen
2082   // so calling them at this point is matters (not before when there
2083   // are fewer objects and not later after there are more objects
2084   // in the perm gen.
2085   Universe::initialize_basic_type_mirrors(CHECK);
2086   Universe::fixup_mirrors(CHECK);
2087 
2088   // do a bunch more:
2089   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2090 
2091   // Preload ref klasses and set reference types
2092   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2093   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2094 
2095   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2096   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2097   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2098   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2099   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2100 
2101   // JSR 292 classes
2102   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2103   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2104   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
2105   initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
2106   initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
2107 
2108   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2109   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2110   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2111   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2112   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2113   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2114   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2115   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2116   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2117   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2118 
2119   { // Compute whether we should use checkPackageAccess or NOT
2120     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2121     _has_checkPackageAccess = (method != NULL);
2122   }
2123 }
2124 
2125 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2126 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2127 BasicType SystemDictionary::box_klass_type(Klass* k) {
2128   assert(k != NULL, "");
2129   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2130     if (_box_klasses[i] == k)
2131       return (BasicType)i;
2132   }
2133   return T_OBJECT;
2134 }
2135 
2136 // Constraints on class loaders. The details of the algorithm can be
2137 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2138 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2139 // that the dictionary needs to maintain a set of contraints that
2140 // must be satisfied by all classes in the dictionary.
2141 // if defining is true, then LinkageError if already in dictionary
2142 // if initiating loader, then ok if InstanceKlass matches existing entry
2143 
2144 void SystemDictionary::check_constraints(unsigned int d_hash,
2145                                          InstanceKlass* k,
2146                                          Handle class_loader, bool defining,
2147                                          TRAPS) {
2148   const char *linkage_error1 = NULL;
2149   const char *linkage_error2 = NULL;
2150   {
2151     Symbol*  name  = k->name();
2152     ClassLoaderData *loader_data = class_loader_data(class_loader);
2153 
2154     MutexLocker mu(SystemDictionary_lock, THREAD);
2155 
2156     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2157     if (check != NULL) {
2158       // if different InstanceKlass - duplicate class definition,
2159       // else - ok, class loaded by a different thread in parallel,
2160       // we should only have found it if it was done loading and ok to use
2161       // dictionary only holds instance classes, placeholders
2162       // also holds array classes
2163 
2164       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2165       if ((defining == true) || (k != check)) {
2166         linkage_error1 = "loader (instance of ";
2167         linkage_error2 = "): attempted duplicate class definition for name: \"";
2168       } else {
2169         return;
2170       }
2171     }
2172 
2173 #ifdef ASSERT
2174     Symbol* ph_check = find_placeholder(name, loader_data);
2175     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2176 #endif
2177 
2178     if (linkage_error1 == NULL) {
2179       if (constraints()->check_or_update(k, class_loader, name) == false) {
2180         linkage_error1 = "loader constraint violation: loader (instance of ";
2181         linkage_error2 = ") previously initiated loading for a different type with name \"";
2182       }
2183     }
2184   }
2185 
2186   // Throw error now if needed (cannot throw while holding
2187   // SystemDictionary_lock because of rank ordering)
2188 
2189   if (linkage_error1) {
2190     ResourceMark rm(THREAD);
2191     const char* class_loader_name = loader_name(class_loader());
2192     char* type_name = k->name()->as_C_string();
2193     size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2194       strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2195     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2196     jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2197     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2198   }
2199 }
2200 
2201 
2202 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2203 // have been called.
2204 void SystemDictionary::update_dictionary(unsigned int d_hash,
2205                                          int p_index, unsigned int p_hash,
2206                                          InstanceKlass* k,
2207                                          Handle class_loader,
2208                                          TRAPS) {
2209   // Compile_lock prevents systemDictionary updates during compilations
2210   assert_locked_or_safepoint(Compile_lock);
2211   Symbol*  name  = k->name();
2212   ClassLoaderData *loader_data = class_loader_data(class_loader);
2213 
2214   {
2215     MutexLocker mu1(SystemDictionary_lock, THREAD);
2216 
2217     // See whether biased locking is enabled and if so set it for this
2218     // klass.
2219     // Note that this must be done past the last potential blocking
2220     // point / safepoint. We enable biased locking lazily using a
2221     // VM_Operation to iterate the SystemDictionary and installing the
2222     // biasable mark word into each InstanceKlass's prototype header.
2223     // To avoid race conditions where we accidentally miss enabling the
2224     // optimization for one class in the process of being added to the
2225     // dictionary, we must not safepoint after the test of
2226     // BiasedLocking::enabled().
2227     if (UseBiasedLocking && BiasedLocking::enabled()) {
2228       // Set biased locking bit for all loaded classes; it will be
2229       // cleared if revocation occurs too often for this type
2230       // NOTE that we must only do this when the class is initally
2231       // defined, not each time it is referenced from a new class loader
2232       if (k->class_loader() == class_loader()) {
2233         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2234       }
2235     }
2236 
2237     // Make a new dictionary entry.
2238     Dictionary* dictionary = loader_data->dictionary();
2239     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2240     if (sd_check == NULL) {
2241       dictionary->add_klass(d_hash, name, k);
2242       notice_modification();
2243     }
2244   #ifdef ASSERT
2245     sd_check = find_class(d_hash, name, dictionary);
2246     assert (sd_check != NULL, "should have entry in dictionary");
2247     // Note: there may be a placeholder entry: for circularity testing
2248     // or for parallel defines
2249   #endif
2250     SystemDictionary_lock->notify_all();
2251   }
2252 }
2253 
2254 
2255 // Try to find a class name using the loader constraints.  The
2256 // loader constraints might know about a class that isn't fully loaded
2257 // yet and these will be ignored.
2258 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2259                     Symbol* class_name, Handle class_loader, TRAPS) {
2260 
2261   // First see if it has been loaded directly.
2262   // Force the protection domain to be null.  (This removes protection checks.)
2263   Handle no_protection_domain;
2264   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2265                                               no_protection_domain, CHECK_NULL);
2266   if (klass != NULL)
2267     return klass;
2268 
2269   // Now look to see if it has been loaded elsewhere, and is subject to
2270   // a loader constraint that would require this loader to return the
2271   // klass that is already loaded.
2272   if (FieldType::is_array(class_name)) {
2273     // For array classes, their Klass*s are not kept in the
2274     // constraint table. The element Klass*s are.
2275     FieldArrayInfo fd;
2276     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2277     if (t != T_OBJECT) {
2278       klass = Universe::typeArrayKlassObj(t);
2279     } else {
2280       MutexLocker mu(SystemDictionary_lock, THREAD);
2281       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2282     }
2283     // If element class already loaded, allocate array klass
2284     if (klass != NULL) {
2285       klass = klass->array_klass_or_null(fd.dimension());
2286     }
2287   } else {
2288     MutexLocker mu(SystemDictionary_lock, THREAD);
2289     // Non-array classes are easy: simply check the constraint table.
2290     klass = constraints()->find_constrained_klass(class_name, class_loader);
2291   }
2292 
2293   return klass;
2294 }
2295 
2296 
2297 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2298                                              Handle class_loader1,
2299                                              Handle class_loader2,
2300                                              Thread* THREAD) {
2301   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2302   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2303 
2304   Symbol* constraint_name = NULL;
2305   if (!FieldType::is_array(class_name)) {
2306     constraint_name = class_name;
2307   } else {
2308     // For array classes, their Klass*s are not kept in the
2309     // constraint table. The element classes are.
2310     FieldArrayInfo fd;
2311     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2312     // primitive types always pass
2313     if (t != T_OBJECT) {
2314       return true;
2315     } else {
2316       constraint_name = fd.object_key();
2317     }
2318   }
2319 
2320   Dictionary* dictionary1 = loader_data1->dictionary();
2321   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2322 
2323   Dictionary* dictionary2 = loader_data2->dictionary();
2324   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2325 
2326   {
2327     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2328     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2329     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2330     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2331                                     klass2, class_loader2);
2332   }
2333 }
2334 
2335 // Add entry to resolution error table to record the error when the first
2336 // attempt to resolve a reference to a class has failed.
2337 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2338                                             Symbol* error, Symbol* message) {
2339   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2340   int index = resolution_errors()->hash_to_index(hash);
2341   {
2342     MutexLocker ml(SystemDictionary_lock, Thread::current());
2343     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2344   }
2345 }
2346 
2347 // Delete a resolution error for RedefineClasses for a constant pool is going away
2348 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2349   resolution_errors()->delete_entry(pool);
2350 }
2351 
2352 // Lookup resolution error table. Returns error if found, otherwise NULL.
2353 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2354                                                 Symbol** message) {
2355   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2356   int index = resolution_errors()->hash_to_index(hash);
2357   {
2358     MutexLocker ml(SystemDictionary_lock, Thread::current());
2359     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2360     if (entry != NULL) {
2361       *message = entry->message();
2362       return entry->error();
2363     } else {
2364       return NULL;
2365     }
2366   }
2367 }
2368 
2369 
2370 // Signature constraints ensure that callers and callees agree about
2371 // the meaning of type names in their signatures.  This routine is the
2372 // intake for constraints.  It collects them from several places:
2373 //
2374 //  * LinkResolver::resolve_method (if check_access is true) requires
2375 //    that the resolving class (the caller) and the defining class of
2376 //    the resolved method (the callee) agree on each type in the
2377 //    method's signature.
2378 //
2379 //  * LinkResolver::resolve_interface_method performs exactly the same
2380 //    checks.
2381 //
2382 //  * LinkResolver::resolve_field requires that the constant pool
2383 //    attempting to link to a field agree with the field's defining
2384 //    class about the type of the field signature.
2385 //
2386 //  * klassVtable::initialize_vtable requires that, when a class
2387 //    overrides a vtable entry allocated by a superclass, that the
2388 //    overriding method (i.e., the callee) agree with the superclass
2389 //    on each type in the method's signature.
2390 //
2391 //  * klassItable::initialize_itable requires that, when a class fills
2392 //    in its itables, for each non-abstract method installed in an
2393 //    itable, the method (i.e., the callee) agree with the interface
2394 //    on each type in the method's signature.
2395 //
2396 // All those methods have a boolean (check_access, checkconstraints)
2397 // which turns off the checks.  This is used from specialized contexts
2398 // such as bootstrapping, dumping, and debugging.
2399 //
2400 // No direct constraint is placed between the class and its
2401 // supertypes.  Constraints are only placed along linked relations
2402 // between callers and callees.  When a method overrides or implements
2403 // an abstract method in a supertype (superclass or interface), the
2404 // constraints are placed as if the supertype were the caller to the
2405 // overriding method.  (This works well, since callers to the
2406 // supertype have already established agreement between themselves and
2407 // the supertype.)  As a result of all this, a class can disagree with
2408 // its supertype about the meaning of a type name, as long as that
2409 // class neither calls a relevant method of the supertype, nor is
2410 // called (perhaps via an override) from the supertype.
2411 //
2412 //
2413 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2414 //
2415 // Make sure all class components (including arrays) in the given
2416 // signature will be resolved to the same class in both loaders.
2417 // Returns the name of the type that failed a loader constraint check, or
2418 // NULL if no constraint failed.  No exception except OOME is thrown.
2419 // Arrays are not added to the loader constraint table, their elements are.
2420 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2421                                                Handle loader1, Handle loader2,
2422                                                bool is_method, TRAPS)  {
2423   // Nothing to do if loaders are the same.
2424   if (loader1() == loader2()) {
2425     return NULL;
2426   }
2427 
2428   SignatureStream sig_strm(signature, is_method);
2429   while (!sig_strm.is_done()) {
2430     if (sig_strm.is_object()) {
2431       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2432       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2433         return sig;
2434       }
2435     }
2436     sig_strm.next();
2437   }
2438   return NULL;
2439 }
2440 
2441 
2442 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2443                                                             Symbol* signature,
2444                                                             TRAPS) {
2445   methodHandle empty;
2446   assert(MethodHandles::is_signature_polymorphic(iid) &&
2447          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2448          iid != vmIntrinsics::_invokeGeneric,
2449          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2450 
2451   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2452   int          index = invoke_method_table()->hash_to_index(hash);
2453   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2454   methodHandle m;
2455   if (spe == NULL || spe->method() == NULL) {
2456     spe = NULL;
2457     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2458     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2459     if (!Arguments::is_interpreter_only()) {
2460       // Generate a compiled form of the MH intrinsic.
2461       AdapterHandlerLibrary::create_native_wrapper(m);
2462       // Check if have the compiled code.
2463       if (!m->has_compiled_code()) {
2464         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2465                    "Out of space in CodeCache for method handle intrinsic", empty);
2466       }
2467     }
2468     // Now grab the lock.  We might have to throw away the new method,
2469     // if a racing thread has managed to install one at the same time.
2470     {
2471       MutexLocker ml(SystemDictionary_lock, THREAD);
2472       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2473       if (spe == NULL)
2474         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2475       if (spe->method() == NULL)
2476         spe->set_method(m());
2477     }
2478   }
2479 
2480   assert(spe != NULL && spe->method() != NULL, "");
2481   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2482          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2483          "MH intrinsic invariant");
2484   return spe->method();
2485 }
2486 
2487 // Helper for unpacking the return value from linkMethod and linkCallSite.
2488 static methodHandle unpack_method_and_appendix(Handle mname,
2489                                                Klass* accessing_klass,
2490                                                objArrayHandle appendix_box,
2491                                                Handle* appendix_result,
2492                                                TRAPS) {
2493   methodHandle empty;
2494   if (mname.not_null()) {
2495     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2496     if (m != NULL) {
2497       oop appendix = appendix_box->obj_at(0);
2498       if (TraceMethodHandles) {
2499     #ifndef PRODUCT
2500         ttyLocker ttyl;
2501         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2502         m->print();
2503         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2504         tty->cr();
2505     #endif //PRODUCT
2506       }
2507       (*appendix_result) = Handle(THREAD, appendix);
2508       // the target is stored in the cpCache and if a reference to this
2509       // MemberName is dropped we need a way to make sure the
2510       // class_loader containing this method is kept alive.
2511       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2512       this_key->record_dependency(m->method_holder());
2513       return methodHandle(THREAD, m);
2514     }
2515   }
2516   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2517   return empty;
2518 }
2519 
2520 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2521                                                           Symbol* name,
2522                                                           Symbol* signature,
2523                                                           Klass* accessing_klass,
2524                                                           Handle *appendix_result,
2525                                                           Handle *method_type_result,
2526                                                           TRAPS) {
2527   methodHandle empty;
2528   assert(THREAD->can_call_java() ,"");
2529   Handle method_type =
2530     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2531 
2532   int ref_kind = JVM_REF_invokeVirtual;
2533   oop name_oop = StringTable::intern(name, CHECK_(empty));
2534   Handle name_str (THREAD, name_oop);
2535   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2536   assert(appendix_box->obj_at(0) == NULL, "");
2537 
2538   // This should not happen.  JDK code should take care of that.
2539   if (accessing_klass == NULL || method_type.is_null()) {
2540     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2541   }
2542 
2543   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2544   JavaCallArguments args;
2545   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2546   args.push_int(ref_kind);
2547   args.push_oop(Handle(THREAD, klass->java_mirror()));
2548   args.push_oop(name_str);
2549   args.push_oop(method_type);
2550   args.push_oop(appendix_box);
2551   JavaValue result(T_OBJECT);
2552   JavaCalls::call_static(&result,
2553                          SystemDictionary::MethodHandleNatives_klass(),
2554                          vmSymbols::linkMethod_name(),
2555                          vmSymbols::linkMethod_signature(),
2556                          &args, CHECK_(empty));
2557   Handle mname(THREAD, (oop) result.get_jobject());
2558   (*method_type_result) = method_type;
2559   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2560 }
2561 
2562 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2563 // We must ensure that all class loaders everywhere will reach this class, for any client.
2564 // This is a safe bet for public classes in java.lang, such as Object and String.
2565 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2566 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2567 static bool is_always_visible_class(oop mirror) {
2568   Klass* klass = java_lang_Class::as_Klass(mirror);
2569   if (klass->is_objArray_klass()) {
2570     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2571   }
2572   if (klass->is_typeArray_klass()) {
2573     return true; // primitive array
2574   }
2575   assert(klass->is_instance_klass(), "%s", klass->external_name());
2576   return klass->is_public() &&
2577          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2578           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2579 }
2580 
2581 
2582 // Return the Java mirror (java.lang.Class instance) for a single-character
2583 // descriptor.  This result, when available, is the same as produced by the
2584 // heavier API point of the same name that takes a Symbol.
2585 oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
2586   return java_lang_Class::primitive_mirror(char2type(signature_char));
2587 }
2588 
2589 // Find or construct the Java mirror (java.lang.Class instance) for a
2590 // for the given field type signature, as interpreted relative to the
2591 // given class loader.  Handles primitives, void, references, arrays,
2592 // and all other reflectable types, except method types.
2593 // N.B.  Code in reflection should use this entry point.
2594 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2595                                                    Klass* accessing_klass,
2596                                                    Handle class_loader,
2597                                                    Handle protection_domain,
2598                                                    SignatureStream::FailureMode failure_mode,
2599                                                    TRAPS) {
2600   Handle empty;
2601 
2602   assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2603          "one or the other, or perhaps neither");
2604 
2605   Symbol* type = signature;
2606 
2607   // What we have here must be a valid field descriptor,
2608   // and all valid field descriptors are supported.
2609   // Produce the same java.lang.Class that reflection reports.
2610   if (type->utf8_length() == 1) {
2611 
2612     // It's a primitive.  (Void has a primitive mirror too.)
2613     char ch = (char) type->byte_at(0);
2614     assert(is_java_primitive(char2type(ch)) || ch == 'V', "");
2615     return Handle(THREAD, find_java_mirror_for_type(ch));
2616 
2617   } else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
2618 
2619     // It's a reference type.
2620     if (accessing_klass != NULL) {
2621       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2622       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2623     }
2624     Klass* constant_type_klass;
2625     if (failure_mode == SignatureStream::ReturnNull) {
2626       constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
2627                                             CHECK_(empty));
2628     } else {
2629       bool throw_error = (failure_mode == SignatureStream::NCDFError);
2630       constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
2631                                             throw_error, CHECK_(empty));
2632     }
2633     if (constant_type_klass == NULL) {
2634       return Handle();  // report failure this way
2635     }
2636     Handle mirror(THREAD, constant_type_klass->java_mirror());
2637 
2638     // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2639     if (accessing_klass != NULL) {
2640       Klass* sel_klass = constant_type_klass;
2641       bool fold_type_to_class = true;
2642       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2643                                               fold_type_to_class, CHECK_(empty));
2644     }
2645 
2646     return mirror;
2647 
2648   }
2649 
2650   // Fall through to an error.
2651   assert(false, "unsupported mirror syntax");
2652   THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2653 }
2654 
2655 
2656 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2657 // signature, as interpreted relative to the given class loader.
2658 // Because of class loader constraints, all method handle usage must be
2659 // consistent with this loader.
2660 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2661                                                  Klass* accessing_klass,
2662                                                  TRAPS) {
2663   Handle empty;
2664   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2665   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2666   int          index = invoke_method_table()->hash_to_index(hash);
2667   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2668   if (spe != NULL && spe->method_type() != NULL) {
2669     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2670     return Handle(THREAD, spe->method_type());
2671   } else if (!THREAD->can_call_java()) {
2672     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2673     return Handle();  // do not attempt from within compiler, unless it was cached
2674   }
2675 
2676   Handle class_loader, protection_domain;
2677   if (accessing_klass != NULL) {
2678     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2679     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2680   }
2681   bool can_be_cached = true;
2682   int npts = ArgumentCount(signature).size();
2683   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2684   int arg = 0;
2685   Handle rt; // the return type from the signature
2686   ResourceMark rm(THREAD);
2687   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2688     oop mirror = NULL;
2689     if (can_be_cached) {
2690       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2691       mirror = ss.as_java_mirror(Handle(), Handle(),
2692                                  SignatureStream::ReturnNull, CHECK_(empty));
2693       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2694         // Fall back to accessing_klass context.
2695         can_be_cached = false;
2696       }
2697     }
2698     if (!can_be_cached) {
2699       // Resolve, throwing a real error if it doesn't work.
2700       mirror = ss.as_java_mirror(class_loader, protection_domain,
2701                                  SignatureStream::NCDFError, CHECK_(empty));
2702     }
2703     assert(mirror != NULL, "%s", ss.as_symbol(THREAD)->as_C_string());
2704     if (ss.at_return_type())
2705       rt = Handle(THREAD, mirror);
2706     else
2707       pts->obj_at_put(arg++, mirror);
2708 
2709     // Check accessibility.
2710     if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2711       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2712       mirror = NULL;  // safety
2713       // Emulate ConstantPool::verify_constant_pool_resolve.
2714       bool fold_type_to_class = true;
2715       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2716                                               fold_type_to_class, CHECK_(empty));
2717     }
2718   }
2719   assert(arg == npts, "");
2720 
2721   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2722   JavaCallArguments args(Handle(THREAD, rt()));
2723   args.push_oop(pts);
2724   JavaValue result(T_OBJECT);
2725   JavaCalls::call_static(&result,
2726                          SystemDictionary::MethodHandleNatives_klass(),
2727                          vmSymbols::findMethodHandleType_name(),
2728                          vmSymbols::findMethodHandleType_signature(),
2729                          &args, CHECK_(empty));
2730   Handle method_type(THREAD, (oop) result.get_jobject());
2731 
2732   if (can_be_cached) {
2733     // We can cache this MethodType inside the JVM.
2734     MutexLocker ml(SystemDictionary_lock, THREAD);
2735     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2736     if (spe == NULL)
2737       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2738     if (spe->method_type() == NULL) {
2739       spe->set_method_type(method_type());
2740     }
2741   }
2742 
2743   // report back to the caller with the MethodType
2744   return method_type;
2745 }
2746 
2747 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2748                                                 Klass* accessing_klass,
2749                                                 TRAPS) {
2750   Handle empty;
2751   ResourceMark rm(THREAD);
2752   SignatureStream ss(signature, /*is_method=*/ false);
2753   if (!ss.is_done()) {
2754     Handle class_loader, protection_domain;
2755     if (accessing_klass != NULL) {
2756       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2757       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2758     }
2759     oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2760     ss.next();
2761     if (ss.is_done()) {
2762       return Handle(THREAD, mirror);
2763     }
2764   }
2765   return empty;
2766 }
2767 
2768 // Ask Java code to find or construct a method handle constant.
2769 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2770                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2771                                                      Klass* callee,
2772                                                      Symbol* name,
2773                                                      Symbol* signature,
2774                                                      TRAPS) {
2775   Handle empty;
2776   if (caller == NULL) {
2777     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2778   }
2779   Handle name_str      = java_lang_String::create_from_symbol(name,      CHECK_(empty));
2780   Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2781 
2782   // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2783   Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2784   java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2785   java_lang_invoke_MemberName::set_name (mname(), name_str());
2786   java_lang_invoke_MemberName::set_type (mname(), signature_str());
2787   java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2788 
2789   if (ref_kind == JVM_REF_invokeVirtual &&
2790       callee->name() == vmSymbols::java_lang_invoke_MethodHandle() &&
2791       (name == vmSymbols::invoke_name() || name == vmSymbols::invokeExact_name())) {
2792     // Skip resolution for j.l.i.MethodHandle.invoke()/invokeExact().
2793     // They are public signature polymorphic methods, but require appendix argument
2794     // which MemberName resolution doesn't handle. There's special logic on JDK side to handle them
2795     // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2796   } else {
2797     MethodHandles::resolve_MemberName(mname, caller, CHECK_(empty));
2798   }
2799 
2800   // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2801   Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2802 
2803   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2804   JavaCallArguments args;
2805   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2806   args.push_int(ref_kind);
2807   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2808   args.push_oop(name_str);
2809   args.push_oop(type);
2810   JavaValue result(T_OBJECT);
2811   JavaCalls::call_static(&result,
2812                          SystemDictionary::MethodHandleNatives_klass(),
2813                          vmSymbols::linkMethodHandleConstant_name(),
2814                          vmSymbols::linkMethodHandleConstant_signature(),
2815                          &args, CHECK_(empty));
2816   return Handle(THREAD, (oop) result.get_jobject());
2817 }
2818 
2819 // Ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry
2820 Handle SystemDictionary::link_dynamic_constant(Klass* caller,
2821                                                int condy_index,
2822                                                Handle bootstrap_specifier,
2823                                                Symbol* name,
2824                                                Symbol* type,
2825                                                TRAPS) {
2826   Handle empty;
2827   Handle bsm, info;
2828   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2829     bsm = bootstrap_specifier;
2830   } else {
2831     assert(bootstrap_specifier->is_objArray(), "");
2832     objArrayOop args = (objArrayOop) bootstrap_specifier();
2833     assert(args->length() == 2, "");
2834     bsm  = Handle(THREAD, args->obj_at(0));
2835     info = Handle(THREAD, args->obj_at(1));
2836   }
2837   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2838             "caller must supply a valid BSM");
2839 
2840   // This should not happen.  JDK code should take care of that.
2841   if (caller == NULL) {
2842     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad dynamic constant", empty);
2843   }
2844 
2845   Handle constant_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2846 
2847   // Resolve the constant type in the context of the caller class
2848   Handle type_mirror = find_java_mirror_for_type(type, caller, SignatureStream::NCDFError,
2849                                                  CHECK_(empty));
2850 
2851   // call java.lang.invoke.MethodHandleNatives::linkConstantDyanmic(caller, condy_index, bsm, type, info)
2852   JavaCallArguments args;
2853   args.push_oop(Handle(THREAD, caller->java_mirror()));
2854   args.push_int(condy_index);
2855   args.push_oop(bsm);
2856   args.push_oop(constant_name);
2857   args.push_oop(type_mirror);
2858   args.push_oop(info);
2859   JavaValue result(T_OBJECT);
2860   JavaCalls::call_static(&result,
2861                          SystemDictionary::MethodHandleNatives_klass(),
2862                          vmSymbols::linkDynamicConstant_name(),
2863                          vmSymbols::linkDynamicConstant_signature(),
2864                          &args, CHECK_(empty));
2865 
2866   return Handle(THREAD, (oop) result.get_jobject());
2867 }
2868 
2869 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2870 // name and signature, as interpreted relative to the given class loader.
2871 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller,
2872                                                               int indy_index,
2873                                                               Handle bootstrap_specifier,
2874                                                               Symbol* name,
2875                                                               Symbol* type,
2876                                                               Handle *appendix_result,
2877                                                               Handle *method_type_result,
2878                                                               TRAPS) {
2879   methodHandle empty;
2880   Handle bsm, info;
2881   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2882     bsm = bootstrap_specifier;
2883   } else {
2884     objArrayOop args = (objArrayOop) bootstrap_specifier();
2885     assert(args->length() == 2, "");
2886     bsm  = Handle(THREAD, args->obj_at(0));
2887     info = Handle(THREAD, args->obj_at(1));
2888   }
2889   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2890             "caller must supply a valid BSM");
2891 
2892   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2893   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2894 
2895   // This should not happen.  JDK code should take care of that.
2896   if (caller == NULL || method_type.is_null()) {
2897     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2898   }
2899 
2900   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2901   assert(appendix_box->obj_at(0) == NULL, "");
2902 
2903   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2904   JavaCallArguments args;
2905   args.push_oop(Handle(THREAD, caller->java_mirror()));
2906   args.push_int(indy_index);
2907   args.push_oop(bsm);
2908   args.push_oop(method_name);
2909   args.push_oop(method_type);
2910   args.push_oop(info);
2911   args.push_oop(appendix_box);
2912   JavaValue result(T_OBJECT);
2913   JavaCalls::call_static(&result,
2914                          SystemDictionary::MethodHandleNatives_klass(),
2915                          vmSymbols::linkCallSite_name(),
2916                          vmSymbols::linkCallSite_signature(),
2917                          &args, CHECK_(empty));
2918   Handle mname(THREAD, (oop) result.get_jobject());
2919   (*method_type_result) = method_type;
2920   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2921 }
2922 
2923 // Protection domain cache table handling
2924 
2925 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2926   return _pd_cache_table->get(protection_domain);
2927 }
2928 
2929 #if INCLUDE_CDS
2930 void SystemDictionary::reorder_dictionary_for_sharing() {
2931   ClassLoaderData::the_null_class_loader_data()->dictionary()->reorder_dictionary_for_sharing();
2932 }
2933 #endif
2934 
2935 size_t SystemDictionary::count_bytes_for_buckets() {
2936   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_buckets();
2937 }
2938 
2939 size_t SystemDictionary::count_bytes_for_table() {
2940   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_table();
2941 }
2942 
2943 void SystemDictionary::copy_buckets(char* top, char* end) {
2944   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_buckets(top, end);
2945 }
2946 
2947 void SystemDictionary::copy_table(char* top, char* end) {
2948   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_table(top, end);
2949 }
2950 
2951 // ----------------------------------------------------------------------------
2952 void SystemDictionary::print_shared(outputStream *st) {
2953   shared_dictionary()->print_on(st);
2954 }
2955 
2956 void SystemDictionary::print_on(outputStream *st) {
2957   if (shared_dictionary() != NULL) {
2958     st->print_cr("Shared Dictionary");
2959     shared_dictionary()->print_on(st);
2960     st->cr();
2961   }
2962 
2963   GCMutexLocker mu(SystemDictionary_lock);
2964 
2965   ClassLoaderDataGraph::print_dictionary(st);
2966 
2967   // Placeholders
2968   placeholders()->print_on(st);
2969   st->cr();
2970 
2971   // loader constraints - print under SD_lock
2972   constraints()->print_on(st);
2973   st->cr();
2974 
2975   _pd_cache_table->print_on(st);
2976   st->cr();
2977 }
2978 
2979 void SystemDictionary::verify() {
2980   guarantee(constraints() != NULL,
2981             "Verify of loader constraints failed");
2982   guarantee(placeholders()->number_of_entries() >= 0,
2983             "Verify of placeholders failed");
2984 
2985   GCMutexLocker mu(SystemDictionary_lock);
2986 
2987   // Verify dictionary
2988   ClassLoaderDataGraph::verify_dictionary();
2989 
2990   placeholders()->verify();
2991 
2992   // Verify constraint table
2993   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2994   constraints()->verify(placeholders());
2995 
2996   _pd_cache_table->verify();
2997 }
2998 
2999 void SystemDictionary::dump(outputStream *st, bool verbose) {
3000   assert_locked_or_safepoint(SystemDictionary_lock);
3001   if (verbose) {
3002     print_on(st);
3003   } else {
3004     if (shared_dictionary() != NULL) {
3005       shared_dictionary()->print_table_statistics(st, "Shared Dictionary");
3006     }
3007     ClassLoaderDataGraph::print_dictionary_statistics(st);
3008     placeholders()->print_table_statistics(st, "Placeholder Table");
3009     constraints()->print_table_statistics(st, "LoaderConstraints Table");
3010     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
3011   }
3012 }
3013 
3014 // Utility for dumping dictionaries.
3015 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
3016                                  DCmdWithParser(output, heap),
3017   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
3018            "BOOLEAN", false, "false") {
3019   _dcmdparser.add_dcmd_option(&_verbose);
3020 }
3021 
3022 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
3023   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
3024                          _verbose.value());
3025   VMThread::execute(&dumper);
3026 }
3027 
3028 int SystemDictionaryDCmd::num_arguments() {
3029   ResourceMark rm;
3030   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
3031   if (dcmd != NULL) {
3032     DCmdMark mark(dcmd);
3033     return dcmd->_dcmdparser.num_arguments();
3034   } else {
3035     return 0;
3036   }
3037 }
3038 
3039 class CombineDictionariesClosure : public CLDClosure {
3040   private:
3041     Dictionary* _master_dictionary;
3042   public:
3043     CombineDictionariesClosure(Dictionary* master_dictionary) :
3044       _master_dictionary(master_dictionary) {}
3045     void do_cld(ClassLoaderData* cld) {
3046       ResourceMark rm;
3047       if (cld->is_anonymous()) {
3048         return;
3049       }
3050       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
3051         for (int i = 0; i < cld->dictionary()->table_size(); ++i) {
3052           Dictionary* curr_dictionary = cld->dictionary();
3053           DictionaryEntry* p = curr_dictionary->bucket(i);
3054           while (p != NULL) {
3055             Symbol* name = p->instance_klass()->name();
3056             unsigned int d_hash = _master_dictionary->compute_hash(name);
3057             int d_index = _master_dictionary->hash_to_index(d_hash);
3058             DictionaryEntry* next = p->next();
3059             if (p->literal()->class_loader_data() != cld) {
3060               // This is an initiating class loader entry; don't use it
3061               log_trace(cds)("Skipping initiating cl entry: %s", name->as_C_string());
3062               curr_dictionary->free_entry(p);
3063             } else {
3064               log_trace(cds)("Moved to boot dictionary: %s", name->as_C_string());
3065               curr_dictionary->unlink_entry(p);
3066               p->set_pd_set(NULL); // pd_set is runtime only information and will be reconstructed.
3067               _master_dictionary->add_entry(d_index, p);
3068             }
3069             p = next;
3070           }
3071           *curr_dictionary->bucket_addr(i) = NULL;
3072         }
3073       }
3074     }
3075 };
3076 
3077 // Combining platform and system loader dictionaries into boot loader dictionary.
3078 // During run time, we only have one shared dictionary.
3079 void SystemDictionary::combine_shared_dictionaries() {
3080   assert(DumpSharedSpaces, "dump time only");
3081   // If AppCDS isn't enabled, we only dump the classes in the boot loader dictionary
3082   // into the shared archive.
3083   if (UseAppCDS) {
3084     Dictionary* master_dictionary = ClassLoaderData::the_null_class_loader_data()->dictionary();
3085     CombineDictionariesClosure cdc(master_dictionary);
3086     ClassLoaderDataGraph::cld_do(&cdc);
3087   }
3088 
3089   // These tables are no longer valid or necessary. Keeping them around will
3090   // cause SystemDictionary::verify() to fail. Let's empty them.
3091   _placeholders        = new PlaceholderTable(_placeholder_table_size);
3092   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
3093 
3094   NOT_PRODUCT(SystemDictionary::verify());
3095 }
3096 
3097 // caller needs ResourceMark
3098 const char* SystemDictionary::loader_name(const oop loader) {
3099   return ((loader) == NULL ? "<bootloader>" :
3100           InstanceKlass::cast((loader)->klass())->name()->as_C_string());
3101 }
3102 
3103 // caller needs ResourceMark
3104 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) {
3105   return (loader_data->class_loader() == NULL ? "<bootloader>" :
3106           SystemDictionary::loader_name(loader_data->class_loader()));
3107 }