1 /*
   2  * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "aot/aotLoader.hpp"
  27 #include "classfile/classFileParser.hpp"
  28 #include "classfile/classFileStream.hpp"
  29 #include "classfile/classLoader.hpp"
  30 #include "classfile/classLoaderData.inline.hpp"
  31 #include "classfile/classLoaderExt.hpp"
  32 #include "classfile/dictionary.hpp"
  33 #include "classfile/javaClasses.inline.hpp"
  34 #include "classfile/klassFactory.hpp"
  35 #include "classfile/loaderConstraints.hpp"
  36 #include "classfile/packageEntry.hpp"
  37 #include "classfile/placeholders.hpp"
  38 #include "classfile/protectionDomainCache.hpp"
  39 #include "classfile/resolutionErrors.hpp"
  40 #include "classfile/stringTable.hpp"
  41 #include "classfile/systemDictionary.hpp"
  42 #include "classfile/vmSymbols.hpp"
  43 #include "code/codeCache.hpp"
  44 #include "compiler/compileBroker.hpp"
  45 #include "gc/shared/gcLocker.hpp"
  46 #include "gc/shared/gcTraceTime.inline.hpp"
  47 #include "interpreter/bytecodeStream.hpp"
  48 #include "interpreter/interpreter.hpp"
  49 #include "logging/log.hpp"
  50 #include "logging/logStream.hpp"
  51 #include "memory/filemap.hpp"
  52 #include "memory/metaspaceClosure.hpp"
  53 #include "memory/oopFactory.hpp"
  54 #include "memory/resourceArea.hpp"
  55 #include "oops/instanceKlass.hpp"
  56 #include "oops/instanceRefKlass.hpp"
  57 #include "oops/klass.inline.hpp"
  58 #include "oops/methodData.hpp"
  59 #include "oops/objArrayKlass.hpp"
  60 #include "oops/objArrayOop.inline.hpp"
  61 #include "oops/oop.inline.hpp"
  62 #include "oops/symbol.hpp"
  63 #include "oops/typeArrayKlass.hpp"
  64 #include "prims/jvm.h"
  65 #include "prims/jvmtiEnvBase.hpp"
  66 #include "prims/resolvedMethodTable.hpp"
  67 #include "prims/methodHandles.hpp"
  68 #include "runtime/arguments.hpp"
  69 #include "runtime/arguments_ext.hpp"
  70 #include "runtime/biasedLocking.hpp"
  71 #include "runtime/fieldType.hpp"
  72 #include "runtime/handles.inline.hpp"
  73 #include "runtime/java.hpp"
  74 #include "runtime/javaCalls.hpp"
  75 #include "runtime/mutexLocker.hpp"
  76 #include "runtime/orderAccess.inline.hpp"
  77 #include "runtime/signature.hpp"
  78 #include "services/classLoadingService.hpp"
  79 #include "services/diagnosticCommand.hpp"
  80 #include "services/threadService.hpp"
  81 #include "trace/tracing.hpp"
  82 #include "utilities/macros.hpp"
  83 #if INCLUDE_CDS
  84 #include "classfile/sharedClassUtil.hpp"
  85 #include "classfile/systemDictionaryShared.hpp"
  86 #endif
  87 #if INCLUDE_JVMCI
  88 #include "jvmci/jvmciRuntime.hpp"
  89 #endif
  90 
  91 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  92 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;
  93 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  94 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  95 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
  96 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
  97 
  98 int         SystemDictionary::_number_of_modifications = 0;
  99 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 100 
 101 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 102                                                           =  { NULL /*, NULL...*/ };
 103 
 104 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 105 
 106 oop         SystemDictionary::_java_system_loader         =  NULL;
 107 oop         SystemDictionary::_java_platform_loader       =  NULL;
 108 
 109 bool        SystemDictionary::_has_loadClassInternal      =  false;
 110 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 111 
 112 // lazily initialized klass variables
 113 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
 114 
 115 // Default ProtectionDomainCacheSize value
 116 
 117 const int defaultProtectionDomainCacheSize = 1009;
 118 
 119 
 120 // ----------------------------------------------------------------------------
 121 // Java-level SystemLoader and PlatformLoader
 122 
 123 oop SystemDictionary::java_system_loader() {
 124   return _java_system_loader;
 125 }
 126 
 127 oop SystemDictionary::java_platform_loader() {
 128   return _java_platform_loader;
 129 }
 130 
 131 void SystemDictionary::compute_java_loaders(TRAPS) {
 132   JavaValue result(T_OBJECT);
 133   InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
 134   JavaCalls::call_static(&result,
 135                          class_loader_klass,
 136                          vmSymbols::getSystemClassLoader_name(),
 137                          vmSymbols::void_classloader_signature(),
 138                          CHECK);
 139 
 140   _java_system_loader = (oop)result.get_jobject();
 141 
 142   JavaCalls::call_static(&result,
 143                          class_loader_klass,
 144                          vmSymbols::getPlatformClassLoader_name(),
 145                          vmSymbols::void_classloader_signature(),
 146                          CHECK);
 147 
 148   _java_platform_loader = (oop)result.get_jobject();
 149 
 150   CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
 151 }
 152 
 153 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
 154   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 155   return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
 156 }
 157 
 158 // ----------------------------------------------------------------------------
 159 // Parallel class loading check
 160 
 161 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 162   if (UnsyncloadClass || class_loader.is_null()) return true;
 163   if (AlwaysLockClassLoader) return false;
 164   return java_lang_ClassLoader::parallelCapable(class_loader());
 165 }
 166 // ----------------------------------------------------------------------------
 167 // ParallelDefineClass flag does not apply to bootclass loader
 168 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 169    if (class_loader.is_null()) return false;
 170    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 171      return true;
 172    }
 173    return false;
 174 }
 175 
 176 // Returns true if the passed class loader is the builtin application class loader
 177 // or a custom system class loader. A customer system class loader can be
 178 // specified via -Djava.system.class.loader.
 179 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 180   if (class_loader == NULL) {
 181     return false;
 182   }
 183   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 184        class_loader == _java_system_loader);
 185 }
 186 
 187 // Returns true if the passed class loader is the platform class loader.
 188 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 189   if (class_loader == NULL) {
 190     return false;
 191   }
 192   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 193 }
 194 
 195 // ----------------------------------------------------------------------------
 196 // Resolving of classes
 197 
 198 // Forwards to resolve_or_null
 199 
 200 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 201   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 202   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 203     // can return a null klass
 204     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 205   }
 206   return klass;
 207 }
 208 
 209 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 210                                                      bool throw_error,
 211                                                      Klass* klass, TRAPS) {
 212   if (HAS_PENDING_EXCEPTION) {
 213     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 214     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 215     // and if so convert it to a NoClassDefFoundError
 216     // And chain the original ClassNotFoundException
 217     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 218       ResourceMark rm(THREAD);
 219       assert(klass == NULL, "Should not have result with exception pending");
 220       Handle e(THREAD, PENDING_EXCEPTION);
 221       CLEAR_PENDING_EXCEPTION;
 222       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 223     } else {
 224       return NULL;
 225     }
 226   }
 227   // Class not found, throw appropriate error or exception depending on value of throw_error
 228   if (klass == NULL) {
 229     ResourceMark rm(THREAD);
 230     if (throw_error) {
 231       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 232     } else {
 233       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 234     }
 235   }
 236   return klass;
 237 }
 238 
 239 
 240 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 241                                            bool throw_error, TRAPS)
 242 {
 243   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 244 }
 245 
 246 
 247 // Forwards to resolve_instance_class_or_null
 248 
 249 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 250   assert(THREAD->can_call_java(),
 251          "can not load classes with compiler thread: class=%s, classloader=%s",
 252          class_name->as_C_string(),
 253          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 254   if (FieldType::is_array(class_name)) {
 255     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 256   } else if (FieldType::is_obj(class_name)) {
 257     ResourceMark rm(THREAD);
 258     // Ignore wrapping L and ;.
 259     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 260                                    class_name->utf8_length() - 2, CHECK_NULL);
 261     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 262   } else {
 263     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 264   }
 265 }
 266 
 267 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 268   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 269 }
 270 
 271 // Forwards to resolve_instance_class_or_null
 272 
 273 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 274                                                      Handle class_loader,
 275                                                      Handle protection_domain,
 276                                                      TRAPS) {
 277   assert(FieldType::is_array(class_name), "must be array");
 278   Klass* k = NULL;
 279   FieldArrayInfo fd;
 280   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 281   // of this call
 282   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 283   if (t == T_OBJECT) {
 284     // naked oop "k" is OK here -- we assign back into it
 285     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 286                                                          class_loader,
 287                                                          protection_domain,
 288                                                          CHECK_NULL);
 289     if (k != NULL) {
 290       k = k->array_klass(fd.dimension(), CHECK_NULL);
 291     }
 292   } else {
 293     k = Universe::typeArrayKlassObj(t);
 294     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 295   }
 296   return k;
 297 }
 298 
 299 
 300 // Must be called for any super-class or super-interface resolution
 301 // during class definition to allow class circularity checking
 302 // super-interface callers:
 303 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 304 // super-class callers:
 305 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 306 //   load_shared_class - while loading a class from shared archive
 307 //   resolve_instance_class_or_null:
 308 //     via: handle_parallel_super_load
 309 //      when resolving a class that has an existing placeholder with
 310 //      a saved superclass [i.e. a defineClass is currently in progress]
 311 //      if another thread is trying to resolve the class, it must do
 312 //      super-class checks on its own thread to catch class circularity
 313 // This last call is critical in class circularity checking for cases
 314 // where classloading is delegated to different threads and the
 315 // classloader lock is released.
 316 // Take the case: Base->Super->Base
 317 //   1. If thread T1 tries to do a defineClass of class Base
 318 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 319 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 320 //    so it tries to load Super
 321 //   3. If we load the class internally, or user classloader uses same thread
 322 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 323 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 324 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 325 //      3.4 calls resolve_super_or_fail Base
 326 //      3.5 finds T1,Base -> throws class circularity
 327 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 328 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 329 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 330 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 331 //      4.4 finds T2, Super -> throws class circularity
 332 // Must be called, even if superclass is null, since this is
 333 // where the placeholder entry is created which claims this
 334 // thread is loading this class/classloader.
 335 // Be careful when modifying this code: once you have run
 336 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 337 // you need to find_and_remove it before returning.
 338 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 339 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 340                                                  Symbol* class_name,
 341                                                  Handle class_loader,
 342                                                  Handle protection_domain,
 343                                                  bool is_superclass,
 344                                                  TRAPS) {
 345 #if INCLUDE_CDS
 346   if (DumpSharedSpaces) {
 347     // Special processing for CDS dump time.
 348     Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 349         class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 350     if (k) {
 351       return k;
 352     }
 353   }
 354 #endif // INCLUDE_CDS
 355 
 356   // Double-check, if child class is already loaded, just return super-class,interface
 357   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 358   // dictionary.
 359   // Make sure there's a placeholder for the *child* before resolving.
 360   // Used as a claim that this thread is currently loading superclass/classloader
 361   // Used here for ClassCircularity checks and also for heap verification
 362   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 363   // Must check ClassCircularity before checking if super class is already loaded.
 364   //
 365   // We might not already have a placeholder if this child_name was
 366   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 367   // the name of the class might not be known until the stream is actually
 368   // parsed.
 369   // Bugs 4643874, 4715493
 370 
 371   ClassLoaderData* loader_data = class_loader_data(class_loader);
 372   Dictionary* dictionary = loader_data->dictionary();
 373   unsigned int d_hash = dictionary->compute_hash(child_name);

 374   unsigned int p_hash = placeholders()->compute_hash(child_name);
 375   int p_index = placeholders()->hash_to_index(p_hash);
 376   // can't throw error holding a lock
 377   bool child_already_loaded = false;
 378   bool throw_circularity_error = false;
 379   {
 380     MutexLocker mu(SystemDictionary_lock, THREAD);
 381     Klass* childk = find_class(d_hash, child_name, dictionary);
 382     Klass* quicksuperk;
 383     // to support // loading: if child done loading, just return superclass
 384     // if class_name, & class_loader don't match:
 385     // if initial define, SD update will give LinkageError
 386     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 387     // so we don't throw an exception here.
 388     // see: nsk redefclass014 & java.lang.instrument Instrument032
 389     if ((childk != NULL ) && (is_superclass) &&
 390        ((quicksuperk = childk->super()) != NULL) &&
 391 
 392          ((quicksuperk->name() == class_name) &&
 393             (quicksuperk->class_loader()  == class_loader()))) {
 394            return quicksuperk;
 395     } else {
 396       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 397       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 398           throw_circularity_error = true;
 399       }
 400     }
 401     if (!throw_circularity_error) {
 402       // Be careful not to exit resolve_super
 403       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 404     }
 405   }
 406   if (throw_circularity_error) {
 407       ResourceMark rm(THREAD);
 408       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 409   }
 410 
 411 // java.lang.Object should have been found above
 412   assert(class_name != NULL, "null super class for resolving");
 413   // Resolve the super class or interface, check results on return
 414   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 415                                                     class_loader,
 416                                                     protection_domain,
 417                                                     THREAD);
 418 
 419   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 420   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 421   // or error. GC used to walk the placeholder table as strong roots.
 422   // The instanceKlass is kept alive because the class loader is on the stack,
 423   // which keeps the loader_data alive, as well as all instanceKlasses in
 424   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 425   {
 426     MutexLocker mu(SystemDictionary_lock, THREAD);
 427     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 428     SystemDictionary_lock->notify_all();
 429   }
 430   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 431     // can null superk
 432     superk = handle_resolution_exception(class_name, true, superk, THREAD);
 433   }
 434 
 435   return superk;
 436 }
 437 
 438 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 439                                                   Handle class_loader,
 440                                                   Handle protection_domain,
 441                                                   TRAPS) {
 442   if(!has_checkPackageAccess()) return;
 443 
 444   // Now we have to call back to java to check if the initating class has access
 445   JavaValue result(T_VOID);
 446   LogTarget(Debug, protectiondomain) lt;
 447   if (lt.is_enabled()) {
 448     ResourceMark rm;
 449     // Print out trace information
 450     LogStream ls(lt);
 451     ls.print_cr("Checking package access");
 452     ls.print("class loader: "); class_loader()->print_value_on(&ls);
 453     ls.print(" protection domain: "); protection_domain()->print_value_on(&ls);
 454     ls.print(" loading: "); klass->print_value_on(&ls);
 455     ls.cr();
 456   }
 457 
 458   // This handle and the class_loader handle passed in keeps this class from
 459   // being unloaded through several GC points.
 460   // The class_loader handle passed in is the initiating loader.
 461   Handle mirror(THREAD, klass->java_mirror());
 462 
 463   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 464   JavaCalls::call_special(&result,
 465                          class_loader,
 466                          system_loader,
 467                          vmSymbols::checkPackageAccess_name(),
 468                          vmSymbols::class_protectiondomain_signature(),
 469                          mirror,
 470                          protection_domain,
 471                          THREAD);
 472 
 473   if (HAS_PENDING_EXCEPTION) {
 474     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 475   } else {
 476    log_debug(protectiondomain)("granted");
 477   }
 478 
 479   if (HAS_PENDING_EXCEPTION) return;
 480 
 481   // If no exception has been thrown, we have validated the protection domain
 482   // Insert the protection domain of the initiating class into the set.
 483   {
 484     ClassLoaderData* loader_data = class_loader_data(class_loader);
 485     Dictionary* dictionary = loader_data->dictionary();
 486 
 487     Symbol*  kn = klass->name();
 488     unsigned int d_hash = dictionary->compute_hash(kn);

 489 
 490     MutexLocker mu(SystemDictionary_lock, THREAD);
 491     int d_index = dictionary->hash_to_index(d_hash);
 492     dictionary->add_protection_domain(d_index, d_hash, klass,
 493                                       protection_domain, THREAD);
 494   }
 495 }
 496 
 497 // We only get here if this thread finds that another thread
 498 // has already claimed the placeholder token for the current operation,
 499 // but that other thread either never owned or gave up the
 500 // object lock
 501 // Waits on SystemDictionary_lock to indicate placeholder table updated
 502 // On return, caller must recheck placeholder table state
 503 //
 504 // We only get here if
 505 //  1) custom classLoader, i.e. not bootstrap classloader
 506 //  2) UnsyncloadClass not set
 507 //  3) 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         // Before UnsyncloadClass:
 598         // We only get here if the application has released the
 599         // classloader lock when another thread was in the middle of loading a
 600         // superclass/superinterface for this class, and now
 601         // this thread is also trying to load this class.
 602         // To minimize surprises, the first thread that started to
 603         // load a class should be the one to complete the loading
 604         // with the classfile it initially expected.
 605         // This logic has the current thread wait once it has done
 606         // all the superclass/superinterface loading it can, until
 607         // the original thread completes the class loading or fails
 608         // If it completes we will use the resulting InstanceKlass
 609         // which we will find below in the systemDictionary.
 610         // We also get here for parallel bootstrap classloader
 611         if (class_loader.is_null()) {
 612           SystemDictionary_lock->wait();
 613         } else {
 614           double_lock_wait(lockObject, THREAD);
 615         }
 616       } else {
 617         // If not in SD and not in PH, other thread's load must have failed
 618         super_load_in_progress = false;
 619       }
 620     }
 621   }
 622   return NULL;
 623 }
 624 
 625 static void post_class_load_event(EventClassLoad* event,
 626                                   const InstanceKlass* k,
 627                                   const ClassLoaderData* init_cld) {
 628 #if INCLUDE_TRACE
 629   assert(event != NULL, "invariant");
 630   assert(k != NULL, "invariant");
 631   if (event->should_commit()) {
 632     event->set_loadedClass(k);
 633     event->set_definingClassLoader(k->class_loader_data());
 634     event->set_initiatingClassLoader(init_cld);
 635     event->commit();
 636   }
 637 #endif // INCLUDE_TRACE
 638 }
 639 
 640 static void class_define_event(InstanceKlass* k,
 641                                const ClassLoaderData* def_cld) {
 642 #if INCLUDE_TRACE
 643   EventClassDefine event;
 644   if (event.should_commit()) {
 645     event.set_definedClass(k);
 646     event.set_definingClassLoader(def_cld);
 647     event.commit();
 648   }
 649 #endif // INCLUDE_TRACE
 650 }
 651 
 652 // Be careful when modifying this code: once you have run
 653 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 654 // you need to find_and_remove it before returning.
 655 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 656 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 657                                                         Handle class_loader,
 658                                                         Handle protection_domain,
 659                                                         TRAPS) {
 660   assert(name != NULL && !FieldType::is_array(name) &&
 661          !FieldType::is_obj(name), "invalid class name");
 662 
 663   EventClassLoad class_load_start_event;
 664 
 665   HandleMark hm(THREAD);
 666 
 667   // Fix for 4474172; see evaluation for more details
 668   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 669   ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
 670   Dictionary* dictionary = loader_data->dictionary();
 671   unsigned int d_hash = dictionary->compute_hash(name);
 672 
 673   // Do lookup to see if class already exist and the protection domain
 674   // has the right access
 675   // This call uses find which checks protection domain already matches
 676   // All subsequent calls use find_class, and set has_loaded_class so that
 677   // before we return a result we call out to java to check for valid protection domain
 678   // to allow returning the Klass* and add it to the pd_set if it is valid
 679   {
 680     Klass* probe = dictionary->find(d_hash, name, protection_domain);

 681     if (probe != NULL) return probe;
 682   }
 683 
 684   // Non-bootstrap class loaders will call out to class loader and
 685   // define via jvm/jni_DefineClass which will acquire the
 686   // class loader object lock to protect against multiple threads
 687   // defining the class in parallel by accident.
 688   // This lock must be acquired here so the waiter will find
 689   // any successful result in the SystemDictionary and not attempt
 690   // the define
 691   // ParallelCapable Classloaders and the bootstrap classloader,
 692   // or all classloaders with UnsyncloadClass do not acquire lock here
 693   bool DoObjectLock = true;
 694   if (is_parallelCapable(class_loader)) {
 695     DoObjectLock = false;
 696   }
 697 
 698   unsigned int p_hash = placeholders()->compute_hash(name);
 699   int p_index = placeholders()->hash_to_index(p_hash);
 700 
 701   // Class is not in SystemDictionary so we have to do loading.
 702   // Make sure we are synchronized on the class loader before we proceed
 703   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 704   check_loader_lock_contention(lockObject, THREAD);
 705   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 706 
 707   // Check again (after locking) if class already exist in SystemDictionary
 708   bool class_has_been_loaded   = false;
 709   bool super_load_in_progress  = false;
 710   bool havesupername = false;
 711   InstanceKlass* k = NULL;
 712   PlaceholderEntry* placeholder;
 713   Symbol* superclassname = NULL;
 714 
 715   {
 716     MutexLocker mu(SystemDictionary_lock, THREAD);
 717     InstanceKlass* check = find_class(d_hash, name, dictionary);
 718     if (check != NULL) {
 719       // Klass is already loaded, so just return it
 720       class_has_been_loaded = true;
 721       k = check;
 722     } else {
 723       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 724       if (placeholder && placeholder->super_load_in_progress()) {
 725          super_load_in_progress = true;
 726          if (placeholder->havesupername() == true) {
 727            superclassname = placeholder->supername();
 728            havesupername = true;
 729          }
 730       }
 731     }
 732   }
 733 
 734   // If the class is in the placeholder table, class loading is in progress
 735   if (super_load_in_progress && havesupername==true) {
 736     k = handle_parallel_super_load(name,
 737                                    superclassname,
 738                                    class_loader,
 739                                    protection_domain,
 740                                    lockObject, THREAD);
 741     if (HAS_PENDING_EXCEPTION) {
 742       return NULL;
 743     }
 744     if (k != NULL) {
 745       class_has_been_loaded = true;
 746     }
 747   }
 748 
 749   bool throw_circularity_error = false;
 750   if (!class_has_been_loaded) {
 751     bool load_instance_added = false;
 752 
 753     // add placeholder entry to record loading instance class
 754     // Five cases:
 755     // All cases need to prevent modifying bootclasssearchpath
 756     // in parallel with a classload of same classname
 757     // Redefineclasses uses existence of the placeholder for the duration
 758     // of the class load to prevent concurrent redefinition of not completely
 759     // defined classes.
 760     // case 1. traditional classloaders that rely on the classloader object lock
 761     //   - no other need for LOAD_INSTANCE
 762     // case 2. traditional classloaders that break the classloader object lock
 763     //    as a deadlock workaround. Detection of this case requires that
 764     //    this check is done while holding the classloader object lock,
 765     //    and that lock is still held when calling classloader's loadClass.
 766     //    For these classloaders, we ensure that the first requestor
 767     //    completes the load and other requestors wait for completion.
 768     // case 3. UnsyncloadClass - don't use objectLocker
 769     //    With this flag, we allow parallel classloading of a
 770     //    class/classloader pair
 771     // case4. Bootstrap classloader - don't own objectLocker
 772     //    This classloader supports parallelism at the classloader level,
 773     //    but only allows a single load of a class/classloader pair.
 774     //    No performance benefit and no deadlock issues.
 775     // case 5. parallelCapable user level classloaders - without objectLocker
 776     //    Allow parallel classloading of a class/classloader pair
 777 
 778     {
 779       MutexLocker mu(SystemDictionary_lock, THREAD);
 780       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 781         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 782         if (oldprobe) {
 783           // only need check_seen_thread once, not on each loop
 784           // 6341374 java/lang/Instrument with -Xcomp
 785           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 786             throw_circularity_error = true;
 787           } else {
 788             // case 1: traditional: should never see load_in_progress.
 789             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 790 
 791               // case 4: bootstrap classloader: prevent futile classloading,
 792               // wait on first requestor
 793               if (class_loader.is_null()) {
 794                 SystemDictionary_lock->wait();
 795               } else {
 796               // case 2: traditional with broken classloader lock. wait on first
 797               // requestor.
 798                 double_lock_wait(lockObject, THREAD);
 799               }
 800               // Check if classloading completed while we were waiting
 801               InstanceKlass* check = find_class(d_hash, name, dictionary);
 802               if (check != NULL) {
 803                 // Klass is already loaded, so just return it
 804                 k = check;
 805                 class_has_been_loaded = true;
 806               }
 807               // check if other thread failed to load and cleaned up
 808               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 809             }
 810           }
 811         }
 812       }
 813       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 814       // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
 815       // LOAD_INSTANCE in parallel
 816 
 817       if (!throw_circularity_error && !class_has_been_loaded) {
 818         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 819         load_instance_added = true;
 820         // For class loaders that do not acquire the classloader object lock,
 821         // if they did not catch another thread holding LOAD_INSTANCE,
 822         // need a check analogous to the acquire ObjectLocker/find_class
 823         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 824         // one final check if the load has already completed
 825         // class loaders holding the ObjectLock shouldn't find the class here
 826         InstanceKlass* check = find_class(d_hash, name, dictionary);
 827         if (check != NULL) {
 828         // Klass is already loaded, so return it after checking/adding protection domain
 829           k = check;
 830           class_has_been_loaded = true;
 831         }
 832       }
 833     }
 834 
 835     // must throw error outside of owning lock
 836     if (throw_circularity_error) {
 837       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 838       ResourceMark rm(THREAD);
 839       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 840     }
 841 
 842     if (!class_has_been_loaded) {
 843 
 844       // Do actual loading
 845       k = load_instance_class(name, class_loader, THREAD);
 846 
 847       // For UnsyncloadClass only
 848       // If they got a linkageError, check if a parallel class load succeeded.
 849       // If it did, then for bytecode resolution the specification requires
 850       // that we return the same result we did for the other thread, i.e. the
 851       // successfully loaded InstanceKlass
 852       // Should not get here for classloaders that support parallelism
 853       // with the new cleaner mechanism, even with AllowParallelDefineClass
 854       // Bootstrap goes through here to allow for an extra guarantee check
 855       if (UnsyncloadClass || (class_loader.is_null())) {
 856         if (k == NULL && HAS_PENDING_EXCEPTION
 857           && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
 858           MutexLocker mu(SystemDictionary_lock, THREAD);
 859           InstanceKlass* check = find_class(d_hash, name, dictionary);
 860           if (check != NULL) {
 861             // Klass is already loaded, so just use it
 862             k = check;
 863             CLEAR_PENDING_EXCEPTION;
 864             guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
 865           }
 866         }
 867       }
 868 
 869       // If everything was OK (no exceptions, no null return value), and
 870       // class_loader is NOT the defining loader, do a little more bookkeeping.
 871       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 872         k->class_loader() != class_loader()) {
 873 
 874         check_constraints(d_hash, k, class_loader, false, THREAD);
 875 
 876         // Need to check for a PENDING_EXCEPTION again; check_constraints
 877         // can throw and doesn't use the CHECK macro.
 878         if (!HAS_PENDING_EXCEPTION) {
 879           { // Grabbing the Compile_lock prevents systemDictionary updates
 880             // during compilations.
 881             MutexLocker mu(Compile_lock, THREAD);
 882             update_dictionary(d_hash, p_index, p_hash,
 883               k, class_loader, THREAD);
 884           }
 885 
 886           if (JvmtiExport::should_post_class_load()) {
 887             Thread *thread = THREAD;
 888             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 889             JvmtiExport::post_class_load((JavaThread *) thread, k);
 890           }
 891         }
 892       }
 893     } // load_instance_class
 894 
 895     if (load_instance_added == true) {
 896       // clean up placeholder entries for LOAD_INSTANCE success or error
 897       // This brackets the SystemDictionary updates for both defining
 898       // and initiating loaders
 899       MutexLocker mu(SystemDictionary_lock, THREAD);
 900       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 901       SystemDictionary_lock->notify_all();
 902     }
 903   }
 904 
 905   if (HAS_PENDING_EXCEPTION || k == NULL) {
 906     return NULL;
 907   }
 908 
 909   post_class_load_event(&class_load_start_event, k, loader_data);
 910 
 911 #ifdef ASSERT
 912   {
 913     ClassLoaderData* loader_data = k->class_loader_data();
 914     MutexLocker mu(SystemDictionary_lock, THREAD);
 915     Klass* kk = find_class(name, loader_data);
 916     assert(kk == k, "should be present in dictionary");
 917   }
 918 #endif
 919 
 920   // return if the protection domain in NULL
 921   if (protection_domain() == NULL) return k;
 922 
 923   // Check the protection domain has the right access
 924   if (dictionary->is_valid_protection_domain(d_hash, name,
 925                                              protection_domain)) {
 926     return k;
 927   }
 928 
 929   // Verify protection domain. If it fails an exception is thrown
 930   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 931 
 932   return k;
 933 }
 934 
 935 
 936 // This routine does not lock the system dictionary.
 937 //
 938 // Since readers don't hold a lock, we must make sure that system
 939 // dictionary entries are only removed at a safepoint (when only one
 940 // thread is running), and are added to in a safe way (all links must
 941 // be updated in an MT-safe manner).
 942 //
 943 // Callers should be aware that an entry could be added just after
 944 // _dictionary->bucket(index) is read here, so the caller will not see
 945 // the new entry.
 946 
 947 Klass* SystemDictionary::find(Symbol* class_name,
 948                               Handle class_loader,
 949                               Handle protection_domain,
 950                               TRAPS) {
 951 
 952   // The result of this call should be consistent with the result
 953   // of the call to resolve_instance_class_or_null().
 954   // See evaluation 6790209 and 4474172 for more details.
 955   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 956   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 957 
 958   if (loader_data == NULL) {
 959     // If the ClassLoaderData has not been setup,
 960     // then the class loader has no entries in the dictionary.
 961     return NULL;
 962   }
 963 
 964   Dictionary* dictionary = loader_data->dictionary();
 965   unsigned int d_hash = dictionary->compute_hash(class_name);
 966   return dictionary->find(d_hash, class_name,

 967                           protection_domain);
 968 }
 969 
 970 
 971 // Look for a loaded instance or array klass by name.  Do not do any loading.
 972 // return NULL in case of error.
 973 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 974                                                       Handle class_loader,
 975                                                       Handle protection_domain,
 976                                                       TRAPS) {
 977   Klass* k = NULL;
 978   assert(class_name != NULL, "class name must be non NULL");
 979 
 980   if (FieldType::is_array(class_name)) {
 981     // The name refers to an array.  Parse the name.
 982     // dimension and object_key in FieldArrayInfo are assigned as a
 983     // side-effect of this call
 984     FieldArrayInfo fd;
 985     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 986     if (t != T_OBJECT) {
 987       k = Universe::typeArrayKlassObj(t);
 988     } else {
 989       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 990     }
 991     if (k != NULL) {
 992       k = k->array_klass_or_null(fd.dimension());
 993     }
 994   } else {
 995     k = find(class_name, class_loader, protection_domain, THREAD);
 996   }
 997   return k;
 998 }
 999 
1000 // Note: this method is much like resolve_from_stream, but
1001 // does not publish the classes via the SystemDictionary.
1002 // Handles unsafe_DefineAnonymousClass and redefineclasses
1003 // RedefinedClasses do not add to the class hierarchy
1004 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
1005                                               Handle class_loader,
1006                                               Handle protection_domain,
1007                                               ClassFileStream* st,
1008                                               const InstanceKlass* host_klass,
1009                                               GrowableArray<Handle>* cp_patches,
1010                                               TRAPS) {
1011 
1012   EventClassLoad class_load_start_event;
1013 
1014   ClassLoaderData* loader_data;
1015   if (host_klass != NULL) {
1016     // Create a new CLD for anonymous class, that uses the same class loader
1017     // as the host_klass
1018     guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1019     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1020   } else {
1021     loader_data = ClassLoaderData::class_loader_data(class_loader());
1022   }
1023 
1024   assert(st != NULL, "invariant");
1025   assert(st->need_verify(), "invariant");
1026 
1027   // Parse stream and create a klass.
1028   // Note that we do this even though this klass might
1029   // already be present in the SystemDictionary, otherwise we would not
1030   // throw potential ClassFormatErrors.
1031 
1032   InstanceKlass* k = KlassFactory::create_from_stream(st,
1033                                                       class_name,
1034                                                       loader_data,
1035                                                       protection_domain,
1036                                                       host_klass,
1037                                                       cp_patches,
1038                                                       CHECK_NULL);
1039 
1040   if (host_klass != NULL && k != NULL) {
1041     // If it's anonymous, initialize it now, since nobody else will.
1042 
1043     {
1044       MutexLocker mu_r(Compile_lock, THREAD);
1045 
1046       // Add to class hierarchy, initialize vtables, and do possible
1047       // deoptimizations.
1048       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1049 
1050       // But, do not add to dictionary.
1051 
1052       // compiled code dependencies need to be validated anyway
1053       notice_modification();
1054     }
1055 
1056     // Rewrite and patch constant pool here.
1057     k->link_class(CHECK_NULL);
1058     if (cp_patches != NULL) {
1059       k->constants()->patch_resolved_references(cp_patches);
1060     }
1061     k->eager_initialize(CHECK_NULL);
1062 
1063     // notify jvmti
1064     if (JvmtiExport::should_post_class_load()) {
1065         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1066         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1067     }
1068 
1069     post_class_load_event(&class_load_start_event, k, loader_data);
1070   }
1071   assert(host_klass != NULL || NULL == cp_patches,
1072          "cp_patches only found with host_klass");
1073 
1074   return k;
1075 }
1076 
1077 // Add a klass to the system from a stream (called by jni_DefineClass and
1078 // JVM_DefineClass).
1079 // Note: class_name can be NULL. In that case we do not know the name of
1080 // the class until we have parsed the stream.
1081 
1082 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1083                                                      Handle class_loader,
1084                                                      Handle protection_domain,
1085                                                      ClassFileStream* st,
1086                                                      TRAPS) {
1087 #if INCLUDE_CDS
1088   ResourceMark rm(THREAD);
1089   if (DumpSharedSpaces && !class_loader.is_null() &&
1090       !ArgumentsExt::using_AppCDS() && strcmp(class_name->as_C_string(), "Unnamed") != 0) {
1091     // If AppCDS is not enabled, don't define the class at dump time (except for the "Unnamed"
1092     // class, which is used by MethodHandles).
1093     THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
1094   }
1095 #endif
1096 
1097   HandleMark hm(THREAD);
1098 
1099   // Classloaders that support parallelism, e.g. bootstrap classloader,
1100   // or all classloaders with UnsyncloadClass do not acquire lock here
1101   bool DoObjectLock = true;
1102   if (is_parallelCapable(class_loader)) {
1103     DoObjectLock = false;
1104   }
1105 
1106   ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1107 
1108   // Make sure we are synchronized on the class loader before we proceed
1109   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1110   check_loader_lock_contention(lockObject, THREAD);
1111   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1112 
1113   assert(st != NULL, "invariant");
1114 
1115   // Parse the stream and create a klass.
1116   // Note that we do this even though this klass might
1117   // already be present in the SystemDictionary, otherwise we would not
1118   // throw potential ClassFormatErrors.
1119  InstanceKlass* k = NULL;
1120 
1121 #if INCLUDE_CDS
1122   if (!DumpSharedSpaces) {
1123     k = SystemDictionaryShared::lookup_from_stream(class_name,
1124                                                    class_loader,
1125                                                    protection_domain,
1126                                                    st,
1127                                                    CHECK_NULL);
1128   }
1129 #endif
1130 
1131   if (k == NULL) {
1132     if (st->buffer() == NULL) {
1133       return NULL;
1134     }
1135     k = KlassFactory::create_from_stream(st,
1136                                          class_name,
1137                                          loader_data,
1138                                          protection_domain,
1139                                          NULL, // host_klass
1140                                          NULL, // cp_patches
1141                                          CHECK_NULL);
1142   }
1143 
1144   assert(k != NULL, "no klass created");
1145   Symbol* h_name = k->name();
1146   assert(class_name == NULL || class_name == h_name, "name mismatch");
1147 
1148   // Add class just loaded
1149   // If a class loader supports parallel classloading handle parallel define requests
1150   // find_or_define_instance_class may return a different InstanceKlass
1151   if (is_parallelCapable(class_loader)) {
1152     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1153     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1154       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1155       assert(defined_k != NULL, "Should have a klass if there's no exception");
1156       loader_data->add_to_deallocate_list(k);
1157       k = defined_k;
1158     }
1159   } else {
1160     define_instance_class(k, THREAD);
1161   }
1162 
1163   // If defining the class throws an exception register 'k' for cleanup.
1164   if (HAS_PENDING_EXCEPTION) {
1165     assert(k != NULL, "Must have an instance klass here!");
1166     loader_data->add_to_deallocate_list(k);
1167     return NULL;
1168   }
1169 
1170   // Make sure we have an entry in the SystemDictionary on success
1171   debug_only( {
1172     MutexLocker mu(SystemDictionary_lock, THREAD);
1173 
1174     Klass* check = find_class(h_name, k->class_loader_data());
1175     assert(check == k, "should be present in the dictionary");
1176   } );
1177 
1178   return k;
1179 }
1180 
1181 #if INCLUDE_CDS
1182 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1183                                              int number_of_entries) {
1184   assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>),
1185          "bad shared dictionary size.");
1186   _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(),
1187                                       _shared_dictionary_size, t, number_of_entries);
1188 }
1189 
1190 
1191 // If there is a shared dictionary, then find the entry for the
1192 // given shared system class, if any.
1193 
1194 InstanceKlass* SystemDictionary::find_shared_class(Symbol* class_name) {
1195   if (shared_dictionary() != NULL) {
1196     unsigned int d_hash = shared_dictionary()->compute_hash(class_name);
1197     int d_index = shared_dictionary()->hash_to_index(d_hash);
1198 
1199     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1200   } else {
1201     return NULL;
1202   }
1203 }
1204 
1205 
1206 // Load a class from the shared spaces (found through the shared system
1207 // dictionary).  Force the superclass and all interfaces to be loaded.
1208 // Update the class definition to include sibling classes and no
1209 // subclasses (yet).  [Classes in the shared space are not part of the
1210 // object hierarchy until loaded.]
1211 
1212 InstanceKlass* SystemDictionary::load_shared_class(
1213                  Symbol* class_name, Handle class_loader, TRAPS) {
1214   InstanceKlass* ik = find_shared_class(class_name);
1215   // Make sure we only return the boot class for the NULL classloader.
1216   if (ik != NULL &&
1217       ik->is_shared_boot_class() && class_loader.is_null()) {
1218     Handle protection_domain;
1219     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1220   }
1221   return NULL;
1222 }
1223 
1224 // Check if a shared class can be loaded by the specific classloader:
1225 //
1226 // NULL classloader:
1227 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1228 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1229 //     be defined in an unnamed module.
1230 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1231                                                InstanceKlass* ik,
1232                                                Handle class_loader, TRAPS) {
1233   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1234          "Cannot use sharing if java.base is patched");
1235   ResourceMark rm;
1236   int path_index = ik->shared_classpath_index();
1237   ClassLoaderData* loader_data = class_loader_data(class_loader);
1238   if (path_index < 0) {
1239     // path_index < 0 indicates that the class is intended for a custom loader
1240     // and should not be loaded by boot/platform/app loaders
1241     if (loader_data->is_builtin_class_loader_data()) {
1242       return false;
1243     } else {
1244       return true;
1245     }
1246   }
1247   SharedClassPathEntry* ent =
1248             (SharedClassPathEntry*)FileMapInfo::shared_classpath(path_index);
1249   if (!Universe::is_module_initialized()) {
1250     assert(ent != NULL && ent->is_modules_image(),
1251            "Loading non-bootstrap classes before the module system is initialized");
1252     assert(class_loader.is_null(), "sanity");
1253     return true;
1254   }
1255   // Get the pkg_entry from the classloader
1256   TempNewSymbol pkg_name = NULL;
1257   PackageEntry* pkg_entry = NULL;
1258   ModuleEntry* mod_entry = NULL;
1259   const char* pkg_string = NULL;
1260   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1261   if (pkg_name != NULL) {
1262     pkg_string = pkg_name->as_C_string();
1263     if (loader_data != NULL) {
1264       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1265     }
1266     if (pkg_entry != NULL) {
1267       mod_entry = pkg_entry->module();
1268     }
1269   }
1270 
1271   // If the archived class is from a module that has been patched at runtime,
1272   // the class cannot be loaded from the archive.
1273   if (mod_entry != NULL && mod_entry->is_patched()) {
1274     return false;
1275   }
1276 
1277   if (class_loader.is_null()) {
1278     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1279     // The NULL classloader can load archived class originated from the
1280     // "modules" jimage and the -Xbootclasspath/a. For class from the
1281     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1282     // by the NULL classloader.
1283     if (mod_entry != NULL) {
1284       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1285       // ModuleEntry's location agrees with the archived class' origination.
1286       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1287         return true; // Module class from the "module" jimage
1288       }
1289     }
1290 
1291     // If the archived class is not from the "module" jimage, the class can be
1292     // loaded by the NULL classloader if
1293     //
1294     // 1. the class is from the unamed package
1295     // 2. or, the class is not from a module defined in the NULL classloader
1296     // 3. or, the class is from an unamed module
1297     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1298       // the class is from the -Xbootclasspath/a
1299       if (pkg_string == NULL ||
1300           pkg_entry == NULL ||
1301           pkg_entry->in_unnamed_module()) {
1302         assert(mod_entry == NULL ||
1303                mod_entry == loader_data->unnamed_module(),
1304                "the unnamed module is not defined in the classloader");
1305         return true;
1306       }
1307     }
1308     return false;
1309   } else {
1310     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1311               ik, class_loader, pkg_string, pkg_name,
1312               pkg_entry, mod_entry, CHECK_(false));
1313     return res;
1314   }
1315 }
1316 
1317 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1318                                                    Handle class_loader,
1319                                                    Handle protection_domain, TRAPS) {
1320 
1321   if (ik != NULL) {
1322     Symbol* class_name = ik->name();
1323 
1324     bool visible = is_shared_class_visible(
1325                             class_name, ik, class_loader, CHECK_NULL);
1326     if (!visible) {
1327       return NULL;
1328     }
1329 
1330     // Resolve the superclass and interfaces. They must be the same
1331     // as in dump time, because the layout of <ik> depends on
1332     // the specific layout of ik->super() and ik->local_interfaces().
1333     //
1334     // If unexpected superclass or interfaces are found, we cannot
1335     // load <ik> from the shared archive.
1336 
1337     if (ik->super() != NULL) {
1338       Symbol*  cn = ik->super()->name();
1339       Klass *s = resolve_super_or_fail(class_name, cn,
1340                                        class_loader, protection_domain, true, CHECK_NULL);
1341       if (s != ik->super()) {
1342         // The dynamically resolved super class is not the same as the one we used during dump time,
1343         // so we cannot use ik.
1344         return NULL;
1345       } else {
1346         assert(s->is_shared(), "must be");
1347       }
1348     }
1349 
1350     Array<Klass*>* interfaces = ik->local_interfaces();
1351     int num_interfaces = interfaces->length();
1352     for (int index = 0; index < num_interfaces; index++) {
1353       Klass* k = interfaces->at(index);
1354       Symbol*  name  = k->name();
1355       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1356       if (k != i) {
1357         // The dynamically resolved interface class is not the same as the one we used during dump time,
1358         // so we cannot use ik.
1359         return NULL;
1360       } else {
1361         assert(i->is_shared(), "must be");
1362       }
1363     }
1364 
1365     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1366         ik, class_name, class_loader, protection_domain, CHECK_NULL);
1367     if (new_ik != NULL) {
1368       // The class is changed by CFLH. Return the new class. The shared class is
1369       // not used.
1370       return new_ik;
1371     }
1372 
1373     // Adjust methods to recover missing data.  They need addresses for
1374     // interpreter entry points and their default native method address
1375     // must be reset.
1376 
1377     // Updating methods must be done under a lock so multiple
1378     // threads don't update these in parallel
1379     //
1380     // Shared classes are all currently loaded by either the bootstrap or
1381     // internal parallel class loaders, so this will never cause a deadlock
1382     // on a custom class loader lock.
1383 
1384     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1385     {
1386       HandleMark hm(THREAD);
1387       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1388       check_loader_lock_contention(lockObject, THREAD);
1389       ObjectLocker ol(lockObject, THREAD, true);
1390       // prohibited package check assumes all classes loaded from archive call
1391       // restore_unshareable_info which calls ik->set_package()
1392       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1393     }
1394 
1395     ik->print_class_load_logging(loader_data, NULL, NULL);
1396 
1397     // For boot loader, ensure that GetSystemPackage knows that a class in this
1398     // package was loaded.
1399     if (class_loader.is_null()) {
1400       int path_index = ik->shared_classpath_index();
1401       ResourceMark rm;
1402       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1403     }
1404 
1405     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1406       // Only dump the classes that can be stored into CDS archive
1407       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1408         ResourceMark rm(THREAD);
1409         classlist_file->print_cr("%s", ik->name()->as_C_string());
1410         classlist_file->flush();
1411       }
1412     }
1413 
1414     // notify a class loaded from shared object
1415     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1416   }
1417 
1418   ik->set_has_passed_fingerprint_check(false);
1419   if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1420     uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1421     uint64_t cds_fp = ik->get_stored_fingerprint();
1422     if (aot_fp != 0 && aot_fp == cds_fp) {
1423       // This class matches with a class saved in an AOT library
1424       ik->set_has_passed_fingerprint_check(true);
1425     } else {
1426       ResourceMark rm;
1427       log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1428     }
1429   }
1430   return ik;
1431 }
1432 
1433 void SystemDictionary::clear_invoke_method_table() {
1434   SymbolPropertyEntry* spe = NULL;
1435   for (int index = 0; index < _invoke_method_table->table_size(); index++) {
1436     SymbolPropertyEntry* p = _invoke_method_table->bucket(index);
1437     while (p != NULL) {
1438       spe = p;
1439       p = p->next();
1440       _invoke_method_table->free_entry(spe);
1441     }
1442   }
1443 }
1444 #endif // INCLUDE_CDS
1445 
1446 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1447 
1448   if (class_loader.is_null()) {
1449     ResourceMark rm;
1450     PackageEntry* pkg_entry = NULL;
1451     bool search_only_bootloader_append = false;
1452     ClassLoaderData *loader_data = class_loader_data(class_loader);
1453 
1454     // Find the package in the boot loader's package entry table.
1455     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1456     if (pkg_name != NULL) {
1457       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1458     }
1459 
1460     // Prior to attempting to load the class, enforce the boot loader's
1461     // visibility boundaries.
1462     if (!Universe::is_module_initialized()) {
1463       // During bootstrapping, prior to module initialization, any
1464       // class attempting to be loaded must be checked against the
1465       // java.base packages in the boot loader's PackageEntryTable.
1466       // No class outside of java.base is allowed to be loaded during
1467       // this bootstrapping window.
1468       if (!DumpSharedSpaces) {
1469         if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1470           // Class is either in the unnamed package or in
1471           // a named package within the unnamed module.  Either
1472           // case is outside of java.base, do not attempt to
1473           // load the class post java.base definition.  If
1474           // java.base has not been defined, let the class load
1475           // and its package will be checked later by
1476           // ModuleEntryTable::verify_javabase_packages.
1477           if (ModuleEntryTable::javabase_defined()) {
1478             return NULL;
1479           }
1480         } else {
1481           // Check that the class' package is defined within java.base.
1482           ModuleEntry* mod_entry = pkg_entry->module();
1483           Symbol* mod_entry_name = mod_entry->name();
1484           if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1485             return NULL;
1486           }
1487         }
1488       }
1489     } else {
1490       // After the module system has been initialized, check if the class'
1491       // package is in a module defined to the boot loader.
1492       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1493         // Class is either in the unnamed package, in a named package
1494         // within a module not defined to the boot loader or in a
1495         // a named package within the unnamed module.  In all cases,
1496         // limit visibility to search for the class only in the boot
1497         // loader's append path.
1498         search_only_bootloader_append = true;
1499       }
1500     }
1501 
1502     // Prior to bootstrapping's module initialization, never load a class outside
1503     // of the boot loader's module path
1504     assert(Universe::is_module_initialized() || DumpSharedSpaces ||
1505            !search_only_bootloader_append,
1506            "Attempt to load a class outside of boot loader's module path");
1507 
1508     // Search the shared system dictionary for classes preloaded into the
1509     // shared spaces.
1510     InstanceKlass* k = NULL;
1511     {
1512 #if INCLUDE_CDS
1513       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1514       k = load_shared_class(class_name, class_loader, THREAD);
1515 #endif
1516     }
1517 
1518     if (k == NULL) {
1519       // Use VM class loader
1520       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1521       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1522     }
1523 
1524     // find_or_define_instance_class may return a different InstanceKlass
1525     if (k != NULL) {
1526       InstanceKlass* defined_k =
1527         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1528       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1529         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1530         assert(defined_k != NULL, "Should have a klass if there's no exception");
1531         loader_data->add_to_deallocate_list(k);
1532         k = defined_k;
1533       } else if (HAS_PENDING_EXCEPTION) {
1534         loader_data->add_to_deallocate_list(k);
1535         return NULL;
1536       }
1537     }
1538     return k;
1539   } else {
1540     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1541     ResourceMark rm(THREAD);
1542 
1543     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1544     JavaThread* jt = (JavaThread*) THREAD;
1545 
1546     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1547                                ClassLoader::perf_app_classload_selftime(),
1548                                ClassLoader::perf_app_classload_count(),
1549                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1550                                jt->get_thread_stat()->perf_timers_addr(),
1551                                PerfClassTraceTime::CLASS_LOAD);
1552 
1553     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1554     // Translate to external class name format, i.e., convert '/' chars to '.'
1555     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1556 
1557     JavaValue result(T_OBJECT);
1558 
1559     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1560 
1561     // Call public unsynchronized loadClass(String) directly for all class loaders
1562     // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1563     // acquire a class-name based lock rather than the class loader object lock.
1564     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1565     // so the call to loadClassInternal() was not required.
1566     //
1567     // UnsyncloadClass flag means both call loadClass(String) and do
1568     // not acquire the class loader lock even for class loaders that are
1569     // not parallelCapable. This was a risky transitional
1570     // flag for diagnostic purposes only. It is risky to call
1571     // custom class loaders without synchronization.
1572     // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1573     // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1574     // Do NOT assume this will be supported in future releases.
1575     //
1576     // Added MustCallLoadClassInternal in case we discover in the field
1577     // a customer that counts on this call
1578     if (MustCallLoadClassInternal && has_loadClassInternal()) {
1579       JavaCalls::call_special(&result,
1580                               class_loader,
1581                               spec_klass,
1582                               vmSymbols::loadClassInternal_name(),
1583                               vmSymbols::string_class_signature(),
1584                               string,
1585                               CHECK_NULL);
1586     } else {
1587       JavaCalls::call_virtual(&result,
1588                               class_loader,
1589                               spec_klass,
1590                               vmSymbols::loadClass_name(),
1591                               vmSymbols::string_class_signature(),
1592                               string,
1593                               CHECK_NULL);
1594     }
1595 
1596     assert(result.get_type() == T_OBJECT, "just checking");
1597     oop obj = (oop) result.get_jobject();
1598 
1599     // Primitive classes return null since forName() can not be
1600     // used to obtain any of the Class objects representing primitives or void
1601     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1602       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1603       // For user defined Java class loaders, check that the name returned is
1604       // the same as that requested.  This check is done for the bootstrap
1605       // loader when parsing the class file.
1606       if (class_name == k->name()) {
1607         return k;
1608       }
1609     }
1610     // Class is not found or has the wrong name, return NULL
1611     return NULL;
1612   }
1613 }
1614 
1615 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1616 
1617   HandleMark hm(THREAD);
1618   ClassLoaderData* loader_data = k->class_loader_data();
1619   Handle class_loader_h(THREAD, loader_data->class_loader());
1620 
1621  // for bootstrap and other parallel classloaders don't acquire lock,
1622  // use placeholder token
1623  // If a parallelCapable class loader calls define_instance_class instead of
1624  // find_or_define_instance_class to get here, we have a timing
1625  // hole with systemDictionary updates and check_constraints
1626  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1627     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1628          compute_loader_lock_object(class_loader_h, THREAD)),
1629          "define called without lock");
1630   }
1631 
1632   // Check class-loading constraints. Throw exception if violation is detected.
1633   // Grabs and releases SystemDictionary_lock
1634   // The check_constraints/find_class call and update_dictionary sequence
1635   // must be "atomic" for a specific class/classloader pair so we never
1636   // define two different instanceKlasses for that class/classloader pair.
1637   // Existing classloaders will call define_instance_class with the
1638   // classloader lock held
1639   // Parallel classloaders will call find_or_define_instance_class
1640   // which will require a token to perform the define class
1641   Symbol*  name_h = k->name();
1642   Dictionary* dictionary = loader_data->dictionary();
1643   unsigned int d_hash = dictionary->compute_hash(name_h);
1644   check_constraints(d_hash, k, class_loader_h, true, CHECK);

1645 
1646   // Register class just loaded with class loader (placed in Vector)
1647   // Note we do this before updating the dictionary, as this can
1648   // fail with an OutOfMemoryError (if it does, we will *not* put this
1649   // class in the dictionary and will not update the class hierarchy).
1650   // JVMTI FollowReferences needs to find the classes this way.
1651   if (k->class_loader() != NULL) {
1652     methodHandle m(THREAD, Universe::loader_addClass_method());
1653     JavaValue result(T_VOID);
1654     JavaCallArguments args(class_loader_h);
1655     args.push_oop(Handle(THREAD, k->java_mirror()));
1656     JavaCalls::call(&result, m, &args, CHECK);
1657   }
1658 
1659   // Add the new class. We need recompile lock during update of CHA.
1660   {
1661     unsigned int p_hash = placeholders()->compute_hash(name_h);
1662     int p_index = placeholders()->hash_to_index(p_hash);
1663 
1664     MutexLocker mu_r(Compile_lock, THREAD);
1665 
1666     // Add to class hierarchy, initialize vtables, and do possible
1667     // deoptimizations.
1668     add_to_hierarchy(k, CHECK); // No exception, but can block
1669 
1670     // Add to systemDictionary - so other classes can see it.
1671     // Grabs and releases SystemDictionary_lock
1672     update_dictionary(d_hash, p_index, p_hash,
1673                       k, class_loader_h, THREAD);
1674   }
1675   k->eager_initialize(THREAD);
1676 
1677   // notify jvmti
1678   if (JvmtiExport::should_post_class_load()) {
1679       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1680       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1681 
1682   }
1683   class_define_event(k, loader_data);
1684 }
1685 
1686 // Support parallel classloading
1687 // All parallel class loaders, including bootstrap classloader
1688 // lock a placeholder entry for this class/class_loader pair
1689 // to allow parallel defines of different classes for this class loader
1690 // With AllowParallelDefine flag==true, in case they do not synchronize around
1691 // FindLoadedClass/DefineClass, calls, we check for parallel
1692 // loading for them, wait if a defineClass is in progress
1693 // and return the initial requestor's results
1694 // This flag does not apply to the bootstrap classloader.
1695 // With AllowParallelDefine flag==false, call through to define_instance_class
1696 // which will throw LinkageError: duplicate class definition.
1697 // False is the requested default.
1698 // For better performance, the class loaders should synchronize
1699 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1700 // potentially waste time reading and parsing the bytestream.
1701 // Note: VM callers should ensure consistency of k/class_name,class_loader
1702 // Be careful when modifying this code: once you have run
1703 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1704 // you need to find_and_remove it before returning.
1705 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1706 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1707                                                                InstanceKlass* k, TRAPS) {
1708 
1709   Symbol*  name_h = k->name(); // passed in class_name may be null
1710   ClassLoaderData* loader_data = class_loader_data(class_loader);
1711   Dictionary* dictionary = loader_data->dictionary();
1712 
1713   unsigned int d_hash = dictionary->compute_hash(name_h);

1714 
1715   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1716   unsigned int p_hash = placeholders()->compute_hash(name_h);
1717   int p_index = placeholders()->hash_to_index(p_hash);
1718   PlaceholderEntry* probe;
1719 
1720   {
1721     MutexLocker mu(SystemDictionary_lock, THREAD);
1722     // First check if class already defined
1723     if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1724       InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1725       if (check != NULL) {
1726         return check;
1727       }
1728     }
1729 
1730     // Acquire define token for this class/classloader
1731     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1732     // Wait if another thread defining in parallel
1733     // All threads wait - even those that will throw duplicate class: otherwise
1734     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1735     // if other thread has not finished updating dictionary
1736     while (probe->definer() != NULL) {
1737       SystemDictionary_lock->wait();
1738     }
1739     // Only special cases allow parallel defines and can use other thread's results
1740     // Other cases fall through, and may run into duplicate defines
1741     // caught by finding an entry in the SystemDictionary
1742     if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1743         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1744         SystemDictionary_lock->notify_all();
1745 #ifdef ASSERT
1746         InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1747         assert(check != NULL, "definer missed recording success");
1748 #endif
1749         return probe->instance_klass();
1750     } else {
1751       // This thread will define the class (even if earlier thread tried and had an error)
1752       probe->set_definer(THREAD);
1753     }
1754   }
1755 
1756   define_instance_class(k, THREAD);
1757 
1758   Handle linkage_exception = Handle(); // null handle
1759 
1760   // definer must notify any waiting threads
1761   {
1762     MutexLocker mu(SystemDictionary_lock, THREAD);
1763     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1764     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1765     if (probe != NULL) {
1766       if (HAS_PENDING_EXCEPTION) {
1767         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1768         CLEAR_PENDING_EXCEPTION;
1769       } else {
1770         probe->set_instance_klass(k);
1771       }
1772       probe->set_definer(NULL);
1773       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1774       SystemDictionary_lock->notify_all();
1775     }
1776   }
1777 
1778   // Can't throw exception while holding lock due to rank ordering
1779   if (linkage_exception() != NULL) {
1780     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1781   }
1782 
1783   return k;
1784 }
1785 
1786 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1787   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1788   if (class_loader.is_null()) {
1789     return Handle(THREAD, _system_loader_lock_obj);
1790   } else {
1791     return class_loader;
1792   }
1793 }
1794 
1795 // This method is added to check how often we have to wait to grab loader
1796 // lock. The results are being recorded in the performance counters defined in
1797 // ClassLoader::_sync_systemLoaderLockContentionRate and
1798 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1799 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1800   if (!UsePerfData) {
1801     return;
1802   }
1803 
1804   assert(!loader_lock.is_null(), "NULL lock object");
1805 
1806   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1807       == ObjectSynchronizer::owner_other) {
1808     // contention will likely happen, so increment the corresponding
1809     // contention counter.
1810     if (loader_lock() == _system_loader_lock_obj) {
1811       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1812     } else {
1813       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1814     }
1815   }
1816 }
1817 
1818 // ----------------------------------------------------------------------------
1819 // Lookup
1820 
1821 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1822                                             Symbol* class_name,
1823                                             Dictionary* dictionary) {
1824   assert_locked_or_safepoint(SystemDictionary_lock);
1825   int index = dictionary->hash_to_index(hash);
1826   return dictionary->find_class(index, hash, class_name);
1827 }
1828 
1829 
1830 // Basic find on classes in the midst of being loaded
1831 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1832                                            ClassLoaderData* loader_data) {
1833   assert_locked_or_safepoint(SystemDictionary_lock);
1834   unsigned int p_hash = placeholders()->compute_hash(class_name);
1835   int p_index = placeholders()->hash_to_index(p_hash);
1836   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1837 }
1838 
1839 
1840 // Used for assertions and verification only
1841 // Precalculating the hash and index is an optimization because there are many lookups
1842 // before adding the class.
1843 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1844   assert_locked_or_safepoint(SystemDictionary_lock);
1845   #ifndef ASSERT
1846   guarantee(VerifyBeforeGC      ||
1847             VerifyDuringGC      ||
1848             VerifyBeforeExit    ||
1849             VerifyDuringStartup ||
1850             VerifyAfterGC, "too expensive");
1851   #endif
1852 
1853   Dictionary* dictionary = loader_data->dictionary();
1854   unsigned int d_hash = dictionary->compute_hash(class_name);
1855   return find_class(d_hash, class_name, dictionary);

1856 }
1857 
1858 
1859 // ----------------------------------------------------------------------------
1860 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1861 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1862 // before a new class is used.
1863 
1864 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1865   assert(k != NULL, "just checking");
1866   assert_locked_or_safepoint(Compile_lock);
1867 
1868   // Link into hierachy. Make sure the vtables are initialized before linking into
1869   k->append_to_sibling_list();                    // add to superklass/sibling list
1870   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1871   k->set_init_state(InstanceKlass::loaded);
1872   // Now flush all code that depended on old class hierarchy.
1873   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1874   // Also, first reinitialize vtable because it may have gotten out of synch
1875   // while the new class wasn't connected to the class hierarchy.
1876   CodeCache::flush_dependents_on(k);
1877 }
1878 
1879 // ----------------------------------------------------------------------------
1880 // GC support
1881 
1882 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1883   roots_oops_do(blk, NULL);
1884 }
1885 
1886 
1887 #ifdef ASSERT
1888 class VerifySDReachableAndLiveClosure : public OopClosure {
1889 private:
1890   BoolObjectClosure* _is_alive;
1891 
1892   template <class T> void do_oop_work(T* p) {
1893     oop obj = oopDesc::load_decode_heap_oop(p);
1894     guarantee(_is_alive->do_object_b(obj), "Oop in protection domain cache table must be live");
1895   }
1896 
1897 public:
1898   VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1899 
1900   virtual void do_oop(oop* p)       { do_oop_work(p); }
1901   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1902 };
1903 #endif
1904 
1905 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1906 // Note: anonymous classes are not in the SD.
1907 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1908                                     GCTimer* gc_timer,
1909                                     bool do_cleaning) {
1910 
1911 
1912   bool unloading_occurred;
1913   {
1914     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1915 
1916     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1917     unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1918                                                             do_cleaning);
1919   }
1920 
1921   if (unloading_occurred) {
1922     GCTraceTime(Debug, gc, phases) t("Dictionary", gc_timer);
1923     constraints()->purge_loader_constraints();
1924     resolution_errors()->purge_resolution_errors();
1925   }
1926 
1927   {
1928     GCTraceTime(Debug, gc, phases) t("ProtectionDomainCacheTable", gc_timer);
1929     // Oops referenced by the protection domain cache table may get unreachable independently
1930     // of the class loader (eg. cached protection domain oops). So we need to
1931     // explicitly unlink them here.
1932     _pd_cache_table->unlink(is_alive);
1933 
1934 #ifdef ASSERT
1935     VerifySDReachableAndLiveClosure cl(is_alive);
1936     _pd_cache_table->oops_do(&cl);
1937 #endif
1938   }
1939 
1940   if (do_cleaning) {
1941     GCTraceTime(Debug, gc, phases) t("ResolvedMethodTable", gc_timer);
1942     ResolvedMethodTable::unlink(is_alive);
1943   }
1944 
1945   return unloading_occurred;
1946 }
1947 
1948 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1949   strong->do_oop(&_java_system_loader);
1950   strong->do_oop(&_java_platform_loader);
1951   strong->do_oop(&_system_loader_lock_obj);
1952   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1953 
1954   // Do strong roots marking if the closures are the same.
1955   if (strong == weak || !ClassUnloading) {
1956     // Only the protection domain oops contain references into the heap. Iterate
1957     // over all of them.
1958     _pd_cache_table->oops_do(strong);
1959   } else {
1960    if (weak != NULL) {
1961      _pd_cache_table->oops_do(weak);
1962    }
1963   }
1964 
1965   // Visit extra methods
1966   invoke_method_table()->oops_do(strong);
1967 
1968   if (weak != NULL) {
1969     ResolvedMethodTable::oops_do(weak);
1970   }
1971 }
1972 
1973 void SystemDictionary::oops_do(OopClosure* f) {
1974   f->do_oop(&_java_system_loader);
1975   f->do_oop(&_java_platform_loader);
1976   f->do_oop(&_system_loader_lock_obj);
1977   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1978 
1979   // Only the protection domain oops contain references into the heap. Iterate
1980   // over all of them.
1981   _pd_cache_table->oops_do(f);
1982 
1983   // Visit extra methods
1984   invoke_method_table()->oops_do(f);
1985 
1986   ResolvedMethodTable::oops_do(f);
1987 }
1988 
1989 // CDS: scan and relocate all classes in the system dictionary.
1990 void SystemDictionary::classes_do(MetaspaceClosure* it) {
1991   ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(it);
1992 }
1993 
1994 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1995 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1996   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1997     it->push(well_known_klass_addr((WKID)id));
1998   }
1999 }
2000 
2001 void SystemDictionary::methods_do(void f(Method*)) {
2002   // Walk methods in loaded classes
2003   ClassLoaderDataGraph::methods_do(f);
2004   // Walk method handle intrinsics
2005   invoke_method_table()->methods_do(f);
2006 }
2007 
2008 class RemoveClassesClosure : public CLDClosure {
2009   public:
2010     void do_cld(ClassLoaderData* cld) {
2011       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
2012         cld->dictionary()->remove_classes_in_error_state();
2013       }
2014     }
2015 };
2016 
2017 void SystemDictionary::remove_classes_in_error_state() {
2018   ClassLoaderData::the_null_class_loader_data()->dictionary()->remove_classes_in_error_state();
2019   RemoveClassesClosure rcc;
2020   ClassLoaderDataGraph::cld_do(&rcc);
2021 }
2022 
2023 // ----------------------------------------------------------------------------
2024 // Lazily load klasses
2025 
2026 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
2027   // if multiple threads calling this function, only one thread will load
2028   // the class.  The other threads will find the loaded version once the
2029   // class is loaded.
2030   Klass* aos = _abstract_ownable_synchronizer_klass;
2031   if (aos == NULL) {
2032     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
2033     // Force a fence to prevent any read before the write completes
2034     OrderAccess::fence();
2035     _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
2036   }
2037 }
2038 
2039 // ----------------------------------------------------------------------------
2040 // Initialization
2041 
2042 void SystemDictionary::initialize(TRAPS) {
2043   // Allocate arrays
2044   _placeholders        = new PlaceholderTable(_placeholder_table_size);
2045   _number_of_modifications = 0;
2046   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
2047   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
2048   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
2049   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
2050 
2051   // Allocate private object used as system class loader lock
2052   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
2053   // Initialize basic classes
2054   initialize_preloaded_classes(CHECK);
2055 }
2056 
2057 // Compact table of directions on the initialization of klasses:
2058 static const short wk_init_info[] = {
2059   #define WK_KLASS_INIT_INFO(name, symbol, option) \
2060     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
2061           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
2062       | (int)SystemDictionary::option ),
2063   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
2064   #undef WK_KLASS_INIT_INFO
2065   0
2066 };
2067 
2068 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
2069   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2070   int  info = wk_init_info[id - FIRST_WKID];
2071   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
2072   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
2073   InstanceKlass** klassp = &_well_known_klasses[id];
2074 
2075   bool must_load;
2076 #if INCLUDE_JVMCI
2077   if (EnableJVMCI) {
2078     // If JVMCI is enabled we require its classes to be found.
2079     must_load = (init_opt < SystemDictionary::Opt) || (init_opt == SystemDictionary::Jvmci);
2080   } else
2081 #endif
2082   {
2083     must_load = (init_opt < SystemDictionary::Opt);
2084   }
2085 
2086   if ((*klassp) == NULL) {
2087     Klass* k;
2088     if (must_load) {
2089       k = resolve_or_fail(symbol, true, CHECK_0); // load required class
2090     } else {
2091       k = resolve_or_null(symbol,       CHECK_0); // load optional klass
2092     }
2093     (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
2094   }
2095   return ((*klassp) != NULL);
2096 }
2097 
2098 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
2099   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
2100   for (int id = (int)start_id; id < (int)limit_id; id++) {
2101     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2102     int info = wk_init_info[id - FIRST_WKID];
2103     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
2104     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
2105 
2106     initialize_wk_klass((WKID)id, opt, CHECK);
2107   }
2108 
2109   // move the starting value forward to the limit:
2110   start_id = limit_id;
2111 }
2112 
2113 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
2114   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
2115 
2116   // Create the ModuleEntry for java.base.  This call needs to be done here,
2117   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
2118   ClassLoader::classLoader_init2(CHECK);
2119 
2120   // Preload commonly used klasses
2121   WKID scan = FIRST_WKID;
2122   // first do Object, then String, Class
2123 #if INCLUDE_CDS
2124   if (UseSharedSpaces) {
2125     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
2126     // Initialize the constant pool for the Object_class
2127     Object_klass()->constants()->restore_unshareable_info(CHECK);
2128     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2129   } else
2130 #endif
2131   {
2132     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2133   }
2134 
2135   // Calculate offsets for String and Class classes since they are loaded and
2136   // can be used after this point.
2137   java_lang_String::compute_offsets();
2138   java_lang_Class::compute_offsets();
2139 
2140   // Fixup mirrors for classes loaded before java.lang.Class.
2141   // These calls iterate over the objects currently in the perm gen
2142   // so calling them at this point is matters (not before when there
2143   // are fewer objects and not later after there are more objects
2144   // in the perm gen.
2145   Universe::initialize_basic_type_mirrors(CHECK);
2146   Universe::fixup_mirrors(CHECK);
2147 
2148   // do a bunch more:
2149   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2150 
2151   // Preload ref klasses and set reference types
2152   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2153   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2154 
2155   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2156   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2157   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2158   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2159   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2160 
2161   // JSR 292 classes
2162   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2163   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2164   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
2165   initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
2166   initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
2167 
2168   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2169   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2170   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2171   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2172   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2173   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2174   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2175   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2176   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2177   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2178 
2179   { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2180     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2181     _has_loadClassInternal = (method != NULL);
2182   }
2183   { // Compute whether we should use checkPackageAccess or NOT
2184     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2185     _has_checkPackageAccess = (method != NULL);
2186   }
2187 }
2188 
2189 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2190 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2191 BasicType SystemDictionary::box_klass_type(Klass* k) {
2192   assert(k != NULL, "");
2193   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2194     if (_box_klasses[i] == k)
2195       return (BasicType)i;
2196   }
2197   return T_OBJECT;
2198 }
2199 
2200 // Constraints on class loaders. The details of the algorithm can be
2201 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2202 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2203 // that the dictionary needs to maintain a set of contraints that
2204 // must be satisfied by all classes in the dictionary.
2205 // if defining is true, then LinkageError if already in dictionary
2206 // if initiating loader, then ok if InstanceKlass matches existing entry
2207 
2208 void SystemDictionary::check_constraints(unsigned int d_hash,
2209                                          InstanceKlass* k,
2210                                          Handle class_loader, bool defining,
2211                                          TRAPS) {
2212   const char *linkage_error1 = NULL;
2213   const char *linkage_error2 = NULL;
2214   {
2215     Symbol*  name  = k->name();
2216     ClassLoaderData *loader_data = class_loader_data(class_loader);
2217 
2218     MutexLocker mu(SystemDictionary_lock, THREAD);
2219 
2220     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2221     if (check != NULL) {
2222       // if different InstanceKlass - duplicate class definition,
2223       // else - ok, class loaded by a different thread in parallel,
2224       // we should only have found it if it was done loading and ok to use
2225       // dictionary only holds instance classes, placeholders
2226       // also holds array classes
2227 
2228       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2229       if ((defining == true) || (k != check)) {
2230         linkage_error1 = "loader (instance of ";
2231         linkage_error2 = "): attempted duplicate class definition for name: \"";
2232       } else {
2233         return;
2234       }
2235     }
2236 
2237 #ifdef ASSERT
2238     Symbol* ph_check = find_placeholder(name, loader_data);
2239     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2240 #endif
2241 
2242     if (linkage_error1 == NULL) {
2243       if (constraints()->check_or_update(k, class_loader, name) == false) {
2244         linkage_error1 = "loader constraint violation: loader (instance of ";
2245         linkage_error2 = ") previously initiated loading for a different type with name \"";
2246       }
2247     }
2248   }
2249 
2250   // Throw error now if needed (cannot throw while holding
2251   // SystemDictionary_lock because of rank ordering)
2252 
2253   if (linkage_error1) {
2254     ResourceMark rm(THREAD);
2255     const char* class_loader_name = loader_name(class_loader());
2256     char* type_name = k->name()->as_C_string();
2257     size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2258       strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2259     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2260     jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2261     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2262   }
2263 }
2264 
2265 
2266 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2267 // have been called.
2268 void SystemDictionary::update_dictionary(unsigned int d_hash,
2269                                          int p_index, unsigned int p_hash,
2270                                          InstanceKlass* k,
2271                                          Handle class_loader,
2272                                          TRAPS) {
2273   // Compile_lock prevents systemDictionary updates during compilations
2274   assert_locked_or_safepoint(Compile_lock);
2275   Symbol*  name  = k->name();
2276   ClassLoaderData *loader_data = class_loader_data(class_loader);
2277 
2278   {
2279     MutexLocker mu1(SystemDictionary_lock, THREAD);
2280 
2281     // See whether biased locking is enabled and if so set it for this
2282     // klass.
2283     // Note that this must be done past the last potential blocking
2284     // point / safepoint. We enable biased locking lazily using a
2285     // VM_Operation to iterate the SystemDictionary and installing the
2286     // biasable mark word into each InstanceKlass's prototype header.
2287     // To avoid race conditions where we accidentally miss enabling the
2288     // optimization for one class in the process of being added to the
2289     // dictionary, we must not safepoint after the test of
2290     // BiasedLocking::enabled().
2291     if (UseBiasedLocking && BiasedLocking::enabled()) {
2292       // Set biased locking bit for all loaded classes; it will be
2293       // cleared if revocation occurs too often for this type
2294       // NOTE that we must only do this when the class is initally
2295       // defined, not each time it is referenced from a new class loader
2296       if (k->class_loader() == class_loader()) {
2297         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2298       }
2299     }
2300 
2301     // Make a new dictionary entry.
2302     Dictionary* dictionary = loader_data->dictionary();
2303     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2304     if (sd_check == NULL) {
2305       dictionary->add_klass(d_hash, name, k);
2306       notice_modification();
2307     }
2308   #ifdef ASSERT
2309     sd_check = find_class(d_hash, name, dictionary);
2310     assert (sd_check != NULL, "should have entry in dictionary");
2311     // Note: there may be a placeholder entry: for circularity testing
2312     // or for parallel defines
2313   #endif
2314     SystemDictionary_lock->notify_all();
2315   }
2316 }
2317 
2318 
2319 // Try to find a class name using the loader constraints.  The
2320 // loader constraints might know about a class that isn't fully loaded
2321 // yet and these will be ignored.
2322 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2323                     Symbol* class_name, Handle class_loader, TRAPS) {
2324 
2325   // First see if it has been loaded directly.
2326   // Force the protection domain to be null.  (This removes protection checks.)
2327   Handle no_protection_domain;
2328   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2329                                               no_protection_domain, CHECK_NULL);
2330   if (klass != NULL)
2331     return klass;
2332 
2333   // Now look to see if it has been loaded elsewhere, and is subject to
2334   // a loader constraint that would require this loader to return the
2335   // klass that is already loaded.
2336   if (FieldType::is_array(class_name)) {
2337     // For array classes, their Klass*s are not kept in the
2338     // constraint table. The element Klass*s are.
2339     FieldArrayInfo fd;
2340     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2341     if (t != T_OBJECT) {
2342       klass = Universe::typeArrayKlassObj(t);
2343     } else {
2344       MutexLocker mu(SystemDictionary_lock, THREAD);
2345       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2346     }
2347     // If element class already loaded, allocate array klass
2348     if (klass != NULL) {
2349       klass = klass->array_klass_or_null(fd.dimension());
2350     }
2351   } else {
2352     MutexLocker mu(SystemDictionary_lock, THREAD);
2353     // Non-array classes are easy: simply check the constraint table.
2354     klass = constraints()->find_constrained_klass(class_name, class_loader);
2355   }
2356 
2357   return klass;
2358 }
2359 
2360 
2361 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2362                                              Handle class_loader1,
2363                                              Handle class_loader2,
2364                                              Thread* THREAD) {
2365   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2366   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2367 
2368   Symbol* constraint_name = NULL;
2369   if (!FieldType::is_array(class_name)) {
2370     constraint_name = class_name;
2371   } else {
2372     // For array classes, their Klass*s are not kept in the
2373     // constraint table. The element classes are.
2374     FieldArrayInfo fd;
2375     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2376     // primitive types always pass
2377     if (t != T_OBJECT) {
2378       return true;
2379     } else {
2380       constraint_name = fd.object_key();
2381     }
2382   }
2383 
2384   Dictionary* dictionary1 = loader_data1->dictionary();
2385   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);

2386 
2387   Dictionary* dictionary2 = loader_data2->dictionary();
2388   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);

2389 
2390   {
2391     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2392     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2393     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2394     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2395                                     klass2, class_loader2);
2396   }
2397 }
2398 
2399 // Add entry to resolution error table to record the error when the first
2400 // attempt to resolve a reference to a class has failed.
2401 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2402                                             Symbol* error, Symbol* message) {
2403   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2404   int index = resolution_errors()->hash_to_index(hash);
2405   {
2406     MutexLocker ml(SystemDictionary_lock, Thread::current());
2407     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2408   }
2409 }
2410 
2411 // Delete a resolution error for RedefineClasses for a constant pool is going away
2412 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2413   resolution_errors()->delete_entry(pool);
2414 }
2415 
2416 // Lookup resolution error table. Returns error if found, otherwise NULL.
2417 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2418                                                 Symbol** message) {
2419   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2420   int index = resolution_errors()->hash_to_index(hash);
2421   {
2422     MutexLocker ml(SystemDictionary_lock, Thread::current());
2423     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2424     if (entry != NULL) {
2425       *message = entry->message();
2426       return entry->error();
2427     } else {
2428       return NULL;
2429     }
2430   }
2431 }
2432 
2433 
2434 // Signature constraints ensure that callers and callees agree about
2435 // the meaning of type names in their signatures.  This routine is the
2436 // intake for constraints.  It collects them from several places:
2437 //
2438 //  * LinkResolver::resolve_method (if check_access is true) requires
2439 //    that the resolving class (the caller) and the defining class of
2440 //    the resolved method (the callee) agree on each type in the
2441 //    method's signature.
2442 //
2443 //  * LinkResolver::resolve_interface_method performs exactly the same
2444 //    checks.
2445 //
2446 //  * LinkResolver::resolve_field requires that the constant pool
2447 //    attempting to link to a field agree with the field's defining
2448 //    class about the type of the field signature.
2449 //
2450 //  * klassVtable::initialize_vtable requires that, when a class
2451 //    overrides a vtable entry allocated by a superclass, that the
2452 //    overriding method (i.e., the callee) agree with the superclass
2453 //    on each type in the method's signature.
2454 //
2455 //  * klassItable::initialize_itable requires that, when a class fills
2456 //    in its itables, for each non-abstract method installed in an
2457 //    itable, the method (i.e., the callee) agree with the interface
2458 //    on each type in the method's signature.
2459 //
2460 // All those methods have a boolean (check_access, checkconstraints)
2461 // which turns off the checks.  This is used from specialized contexts
2462 // such as bootstrapping, dumping, and debugging.
2463 //
2464 // No direct constraint is placed between the class and its
2465 // supertypes.  Constraints are only placed along linked relations
2466 // between callers and callees.  When a method overrides or implements
2467 // an abstract method in a supertype (superclass or interface), the
2468 // constraints are placed as if the supertype were the caller to the
2469 // overriding method.  (This works well, since callers to the
2470 // supertype have already established agreement between themselves and
2471 // the supertype.)  As a result of all this, a class can disagree with
2472 // its supertype about the meaning of a type name, as long as that
2473 // class neither calls a relevant method of the supertype, nor is
2474 // called (perhaps via an override) from the supertype.
2475 //
2476 //
2477 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2478 //
2479 // Make sure all class components (including arrays) in the given
2480 // signature will be resolved to the same class in both loaders.
2481 // Returns the name of the type that failed a loader constraint check, or
2482 // NULL if no constraint failed.  No exception except OOME is thrown.
2483 // Arrays are not added to the loader constraint table, their elements are.
2484 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2485                                                Handle loader1, Handle loader2,
2486                                                bool is_method, TRAPS)  {
2487   // Nothing to do if loaders are the same.
2488   if (loader1() == loader2()) {
2489     return NULL;
2490   }
2491 
2492   SignatureStream sig_strm(signature, is_method);
2493   while (!sig_strm.is_done()) {
2494     if (sig_strm.is_object()) {
2495       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2496       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2497         return sig;
2498       }
2499     }
2500     sig_strm.next();
2501   }
2502   return NULL;
2503 }
2504 
2505 
2506 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2507                                                             Symbol* signature,
2508                                                             TRAPS) {
2509   methodHandle empty;
2510   assert(MethodHandles::is_signature_polymorphic(iid) &&
2511          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2512          iid != vmIntrinsics::_invokeGeneric,
2513          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2514 
2515   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2516   int          index = invoke_method_table()->hash_to_index(hash);
2517   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2518   methodHandle m;
2519   if (spe == NULL || spe->method() == NULL) {
2520     spe = NULL;
2521     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2522     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2523     if (!Arguments::is_interpreter_only()) {
2524       // Generate a compiled form of the MH intrinsic.
2525       AdapterHandlerLibrary::create_native_wrapper(m);
2526       // Check if have the compiled code.
2527       if (!m->has_compiled_code()) {
2528         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2529                    "Out of space in CodeCache for method handle intrinsic", empty);
2530       }
2531     }
2532     // Now grab the lock.  We might have to throw away the new method,
2533     // if a racing thread has managed to install one at the same time.
2534     {
2535       MutexLocker ml(SystemDictionary_lock, THREAD);
2536       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2537       if (spe == NULL)
2538         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2539       if (spe->method() == NULL)
2540         spe->set_method(m());
2541     }
2542   }
2543 
2544   assert(spe != NULL && spe->method() != NULL, "");
2545   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2546          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2547          "MH intrinsic invariant");
2548   return spe->method();
2549 }
2550 
2551 // Helper for unpacking the return value from linkMethod and linkCallSite.
2552 static methodHandle unpack_method_and_appendix(Handle mname,
2553                                                Klass* accessing_klass,
2554                                                objArrayHandle appendix_box,
2555                                                Handle* appendix_result,
2556                                                TRAPS) {
2557   methodHandle empty;
2558   if (mname.not_null()) {
2559     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2560     if (m != NULL) {
2561       oop appendix = appendix_box->obj_at(0);
2562       if (TraceMethodHandles) {
2563     #ifndef PRODUCT
2564         ttyLocker ttyl;
2565         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2566         m->print();
2567         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2568         tty->cr();
2569     #endif //PRODUCT
2570       }
2571       (*appendix_result) = Handle(THREAD, appendix);
2572       // the target is stored in the cpCache and if a reference to this
2573       // MethodName is dropped we need a way to make sure the
2574       // class_loader containing this method is kept alive.
2575       // FIXME: the appendix might also preserve this dependency.
2576       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2577       this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2578       return methodHandle(THREAD, m);
2579     }
2580   }
2581   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2582   return empty;
2583 }
2584 
2585 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2586                                                           Symbol* name,
2587                                                           Symbol* signature,
2588                                                           Klass* accessing_klass,
2589                                                           Handle *appendix_result,
2590                                                           Handle *method_type_result,
2591                                                           TRAPS) {
2592   methodHandle empty;
2593   assert(THREAD->can_call_java() ,"");
2594   Handle method_type =
2595     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2596 
2597   int ref_kind = JVM_REF_invokeVirtual;
2598   oop name_oop = StringTable::intern(name, CHECK_(empty));
2599   Handle name_str (THREAD, name_oop);
2600   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2601   assert(appendix_box->obj_at(0) == NULL, "");
2602 
2603   // This should not happen.  JDK code should take care of that.
2604   if (accessing_klass == NULL || method_type.is_null()) {
2605     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2606   }
2607 
2608   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2609   JavaCallArguments args;
2610   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2611   args.push_int(ref_kind);
2612   args.push_oop(Handle(THREAD, klass->java_mirror()));
2613   args.push_oop(name_str);
2614   args.push_oop(method_type);
2615   args.push_oop(appendix_box);
2616   JavaValue result(T_OBJECT);
2617   JavaCalls::call_static(&result,
2618                          SystemDictionary::MethodHandleNatives_klass(),
2619                          vmSymbols::linkMethod_name(),
2620                          vmSymbols::linkMethod_signature(),
2621                          &args, CHECK_(empty));
2622   Handle mname(THREAD, (oop) result.get_jobject());
2623   (*method_type_result) = method_type;
2624   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2625 }
2626 
2627 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2628 // We must ensure that all class loaders everywhere will reach this class, for any client.
2629 // This is a safe bet for public classes in java.lang, such as Object and String.
2630 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2631 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2632 static bool is_always_visible_class(oop mirror) {
2633   Klass* klass = java_lang_Class::as_Klass(mirror);
2634   if (klass->is_objArray_klass()) {
2635     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2636   }
2637   if (klass->is_typeArray_klass()) {
2638     return true; // primitive array
2639   }
2640   assert(klass->is_instance_klass(), "%s", klass->external_name());
2641   return klass->is_public() &&
2642          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2643           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2644 }
2645 
2646 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2647 // signature, as interpreted relative to the given class loader.
2648 // Because of class loader constraints, all method handle usage must be
2649 // consistent with this loader.
2650 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2651                                                  Klass* accessing_klass,
2652                                                  TRAPS) {
2653   Handle empty;
2654   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2655   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2656   int          index = invoke_method_table()->hash_to_index(hash);
2657   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2658   if (spe != NULL && spe->method_type() != NULL) {
2659     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2660     return Handle(THREAD, spe->method_type());
2661   } else if (!THREAD->can_call_java()) {
2662     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2663     return Handle();  // do not attempt from within compiler, unless it was cached
2664   }
2665 
2666   Handle class_loader, protection_domain;
2667   if (accessing_klass != NULL) {
2668     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2669     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2670   }
2671   bool can_be_cached = true;
2672   int npts = ArgumentCount(signature).size();
2673   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2674   int arg = 0;
2675   Handle rt; // the return type from the signature
2676   ResourceMark rm(THREAD);
2677   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2678     oop mirror = NULL;
2679     if (can_be_cached) {
2680       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2681       mirror = ss.as_java_mirror(Handle(), Handle(),
2682                                  SignatureStream::ReturnNull, CHECK_(empty));
2683       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2684         // Fall back to accessing_klass context.
2685         can_be_cached = false;
2686       }
2687     }
2688     if (!can_be_cached) {
2689       // Resolve, throwing a real error if it doesn't work.
2690       mirror = ss.as_java_mirror(class_loader, protection_domain,
2691                                  SignatureStream::NCDFError, CHECK_(empty));
2692     }
2693     assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2694     if (ss.at_return_type())
2695       rt = Handle(THREAD, mirror);
2696     else
2697       pts->obj_at_put(arg++, mirror);
2698 
2699     // Check accessibility.
2700     if (ss.is_object() && accessing_klass != NULL) {
2701       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2702       mirror = NULL;  // safety
2703       // Emulate ConstantPool::verify_constant_pool_resolve.
2704       if (sel_klass->is_objArray_klass())
2705         sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2706       if (sel_klass->is_instance_klass()) {
2707         LinkResolver::check_klass_accessability(accessing_klass, sel_klass, CHECK_(empty));
2708       }
2709     }
2710   }
2711   assert(arg == npts, "");
2712 
2713   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2714   JavaCallArguments args(Handle(THREAD, rt()));
2715   args.push_oop(pts);
2716   JavaValue result(T_OBJECT);
2717   JavaCalls::call_static(&result,
2718                          SystemDictionary::MethodHandleNatives_klass(),
2719                          vmSymbols::findMethodHandleType_name(),
2720                          vmSymbols::findMethodHandleType_signature(),
2721                          &args, CHECK_(empty));
2722   Handle method_type(THREAD, (oop) result.get_jobject());
2723 
2724   if (can_be_cached) {
2725     // We can cache this MethodType inside the JVM.
2726     MutexLocker ml(SystemDictionary_lock, THREAD);
2727     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2728     if (spe == NULL)
2729       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2730     if (spe->method_type() == NULL) {
2731       spe->set_method_type(method_type());
2732     }
2733   }
2734 
2735   // report back to the caller with the MethodType
2736   return method_type;
2737 }
2738 
2739 // Ask Java code to find or construct a method handle constant.
2740 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2741                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2742                                                      Klass* callee,
2743                                                      Symbol* name_sym,
2744                                                      Symbol* signature,
2745                                                      TRAPS) {
2746   Handle empty;
2747   Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2748   Handle type;
2749   if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2750     type = find_method_handle_type(signature, caller, CHECK_(empty));
2751   } else if (caller == NULL) {
2752     // This should not happen.  JDK code should take care of that.
2753     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2754   } else {
2755     ResourceMark rm(THREAD);
2756     SignatureStream ss(signature, false);
2757     if (!ss.is_done()) {
2758       oop mirror = ss.as_java_mirror(Handle(THREAD, caller->class_loader()),
2759                                      Handle(THREAD, caller->protection_domain()),
2760                                      SignatureStream::NCDFError, CHECK_(empty));
2761       type = Handle(THREAD, mirror);
2762       ss.next();
2763       if (!ss.is_done())  type = Handle();  // error!
2764     }
2765   }
2766   if (type.is_null()) {
2767     THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2768   }
2769 
2770   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2771   JavaCallArguments args;
2772   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2773   args.push_int(ref_kind);
2774   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2775   args.push_oop(name);
2776   args.push_oop(type);
2777   JavaValue result(T_OBJECT);
2778   JavaCalls::call_static(&result,
2779                          SystemDictionary::MethodHandleNatives_klass(),
2780                          vmSymbols::linkMethodHandleConstant_name(),
2781                          vmSymbols::linkMethodHandleConstant_signature(),
2782                          &args, CHECK_(empty));
2783   return Handle(THREAD, (oop) result.get_jobject());
2784 }
2785 
2786 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2787 // name and signature, as interpreted relative to the given class loader.
2788 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller,
2789                                                               Handle bootstrap_specifier,
2790                                                               Symbol* name,
2791                                                               Symbol* type,
2792                                                               Handle *appendix_result,
2793                                                               Handle *method_type_result,
2794                                                               TRAPS) {
2795   methodHandle empty;
2796   Handle bsm, info;
2797   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2798     bsm = bootstrap_specifier;
2799   } else {
2800     assert(bootstrap_specifier->is_objArray(), "");
2801     objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2802     int len = args->length();
2803     assert(len >= 1, "");
2804     bsm = Handle(THREAD, args->obj_at(0));
2805     if (len > 1) {
2806       objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2807       for (int i = 1; i < len; i++)
2808         args1->obj_at_put(i-1, args->obj_at(i));
2809       info = Handle(THREAD, args1);
2810     }
2811   }
2812   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2813             "caller must supply a valid BSM");
2814 
2815   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2816   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2817 
2818   // This should not happen.  JDK code should take care of that.
2819   if (caller == NULL || method_type.is_null()) {
2820     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2821   }
2822 
2823   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2824   assert(appendix_box->obj_at(0) == NULL, "");
2825 
2826   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2827   JavaCallArguments args;
2828   args.push_oop(Handle(THREAD, caller->java_mirror()));
2829   args.push_oop(bsm);
2830   args.push_oop(method_name);
2831   args.push_oop(method_type);
2832   args.push_oop(info);
2833   args.push_oop(appendix_box);
2834   JavaValue result(T_OBJECT);
2835   JavaCalls::call_static(&result,
2836                          SystemDictionary::MethodHandleNatives_klass(),
2837                          vmSymbols::linkCallSite_name(),
2838                          vmSymbols::linkCallSite_signature(),
2839                          &args, CHECK_(empty));
2840   Handle mname(THREAD, (oop) result.get_jobject());
2841   (*method_type_result) = method_type;
2842   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2843 }
2844 
2845 // Protection domain cache table handling
2846 
2847 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2848   return _pd_cache_table->get(protection_domain);
2849 }
2850 
2851 void SystemDictionary::reorder_dictionary_for_sharing() {
2852   ClassLoaderData::the_null_class_loader_data()->dictionary()->reorder_dictionary_for_sharing();
2853 }
2854 
2855 size_t SystemDictionary::count_bytes_for_buckets() {
2856   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_buckets();
2857 }
2858 
2859 size_t SystemDictionary::count_bytes_for_table() {
2860   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_table();
2861 }
2862 
2863 void SystemDictionary::copy_buckets(char* top, char* end) {
2864   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_buckets(top, end);
2865 }
2866 
2867 void SystemDictionary::copy_table(char* top, char* end) {
2868   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_table(top, end);
2869 }
2870 
2871 // ----------------------------------------------------------------------------
2872 void SystemDictionary::print_shared(outputStream *st) {
2873   shared_dictionary()->print_on(st);
2874 }
2875 
2876 void SystemDictionary::print_on(outputStream *st) {
2877   if (shared_dictionary() != NULL) {
2878     st->print_cr("Shared Dictionary");
2879     shared_dictionary()->print_on(st);
2880     st->cr();
2881   }
2882 
2883   GCMutexLocker mu(SystemDictionary_lock);
2884 
2885   ClassLoaderDataGraph::print_dictionary(st);
2886 
2887   // Placeholders
2888   placeholders()->print_on(st);
2889   st->cr();
2890 
2891   // loader constraints - print under SD_lock
2892   constraints()->print_on(st);
2893   st->cr();
2894 
2895   _pd_cache_table->print_on(st);
2896   st->cr();
2897 }
2898 
2899 void SystemDictionary::verify() {
2900   guarantee(constraints() != NULL,
2901             "Verify of loader constraints failed");
2902   guarantee(placeholders()->number_of_entries() >= 0,
2903             "Verify of placeholders failed");
2904 
2905   GCMutexLocker mu(SystemDictionary_lock);
2906 
2907   // Verify dictionary
2908   ClassLoaderDataGraph::verify_dictionary();
2909 
2910   placeholders()->verify();
2911 
2912   // Verify constraint table
2913   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2914   constraints()->verify(placeholders());
2915 
2916   _pd_cache_table->verify();
2917 }
2918 
2919 void SystemDictionary::dump(outputStream *st, bool verbose) {
2920   assert_locked_or_safepoint(SystemDictionary_lock);
2921   if (verbose) {
2922     print_on(st);
2923   } else {
2924     if (shared_dictionary() != NULL) {
2925       shared_dictionary()->print_table_statistics(st, "Shared Dictionary");
2926     }
2927     ClassLoaderDataGraph::print_dictionary_statistics(st);
2928     placeholders()->print_table_statistics(st, "Placeholder Table");
2929     constraints()->print_table_statistics(st, "LoaderConstraints Table");
2930     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
2931   }
2932 }
2933 
2934 // Utility for dumping dictionaries.
2935 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2936                                  DCmdWithParser(output, heap),
2937   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2938            "BOOLEAN", false, "false") {
2939   _dcmdparser.add_dcmd_option(&_verbose);
2940 }
2941 
2942 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2943   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2944                          _verbose.value());
2945   VMThread::execute(&dumper);
2946 }
2947 
2948 int SystemDictionaryDCmd::num_arguments() {
2949   ResourceMark rm;
2950   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
2951   if (dcmd != NULL) {
2952     DCmdMark mark(dcmd);
2953     return dcmd->_dcmdparser.num_arguments();
2954   } else {
2955     return 0;
2956   }
2957 }
2958 
2959 class CombineDictionariesClosure : public CLDClosure {
2960   private:
2961     Dictionary* _master_dictionary;
2962   public:
2963     CombineDictionariesClosure(Dictionary* master_dictionary) :
2964       _master_dictionary(master_dictionary) {}
2965     void do_cld(ClassLoaderData* cld) {
2966       ResourceMark rm;
2967       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
2968         for (int i = 0; i < cld->dictionary()->table_size(); ++i) {
2969           Dictionary* curr_dictionary = cld->dictionary();
2970           DictionaryEntry* p = curr_dictionary->bucket(i);
2971           while (p != NULL) {
2972             Symbol* name = p->instance_klass()->name();
2973             unsigned int d_hash = _master_dictionary->compute_hash(name);
2974             int d_index = _master_dictionary->hash_to_index(d_hash);
2975             DictionaryEntry* next = p->next();
2976             if (p->literal()->class_loader_data() != cld) {
2977               // This is an initiating class loader entry; don't use it
2978               log_trace(cds)("Skipping initiating cl entry: %s", name->as_C_string());
2979               curr_dictionary->free_entry(p);
2980             } else {
2981               log_trace(cds)("Moved to boot dictionary: %s", name->as_C_string());
2982               curr_dictionary->unlink_entry(p);
2983               p->set_pd_set(NULL); // pd_set is runtime only information and will be reconstructed.
2984               _master_dictionary->add_entry(d_index, p);
2985             }
2986             p = next;
2987           }
2988           *curr_dictionary->bucket_addr(i) = NULL;
2989         }
2990       }
2991     }
2992 };
2993 
2994 // Combining platform and system loader dictionaries into boot loader dictionaries.
2995 // During run time, we only have one shared dictionary.
2996 void SystemDictionary::combine_shared_dictionaries() {
2997   assert(DumpSharedSpaces, "dump time only");
2998   Dictionary* master_dictionary = ClassLoaderData::the_null_class_loader_data()->dictionary();
2999   CombineDictionariesClosure cdc(master_dictionary);
3000   ClassLoaderDataGraph::cld_do(&cdc);
3001 
3002   // These tables are no longer valid or necessary. Keeping them around will
3003   // cause SystemDictionary::verify() to fail. Let's empty them.
3004   _placeholders        = new PlaceholderTable(_placeholder_table_size);
3005   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
3006 
3007   NOT_PRODUCT(SystemDictionary::verify());
3008 }
3009 
3010 // caller needs ResourceMark
3011 const char* SystemDictionary::loader_name(const oop loader) {
3012   return ((loader) == NULL ? "<bootloader>" :
3013           InstanceKlass::cast((loader)->klass())->name()->as_C_string());
3014 }
3015 
3016 // caller needs ResourceMark
3017 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) {
3018   return (loader_data->class_loader() == NULL ? "<bootloader>" :
3019           SystemDictionary::loader_name(loader_data->class_loader()));
3020 }
--- EOF ---