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   int d_index = dictionary->hash_to_index(d_hash);
 375   unsigned int p_hash = placeholders()->compute_hash(child_name);
 376   int p_index = placeholders()->hash_to_index(p_hash);
 377   // can't throw error holding a lock
 378   bool child_already_loaded = false;
 379   bool throw_circularity_error = false;
 380   {
 381     MutexLocker mu(SystemDictionary_lock, THREAD);
 382     Klass* childk = find_class(d_index, d_hash, child_name, dictionary);
 383     Klass* quicksuperk;
 384     // to support // loading: if child done loading, just return superclass
 385     // if class_name, & class_loader don't match:
 386     // if initial define, SD update will give LinkageError
 387     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 388     // so we don't throw an exception here.
 389     // see: nsk redefclass014 & java.lang.instrument Instrument032
 390     if ((childk != NULL ) && (is_superclass) &&
 391        ((quicksuperk = childk->super()) != NULL) &&
 392 
 393          ((quicksuperk->name() == class_name) &&
 394             (quicksuperk->class_loader()  == class_loader()))) {
 395            return quicksuperk;
 396     } else {
 397       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 398       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 399           throw_circularity_error = true;
 400       }
 401     }
 402     if (!throw_circularity_error) {
 403       // Be careful not to exit resolve_super
 404       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 405     }
 406   }
 407   if (throw_circularity_error) {
 408       ResourceMark rm(THREAD);
 409       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 410   }
 411 
 412 // java.lang.Object should have been found above
 413   assert(class_name != NULL, "null super class for resolving");
 414   // Resolve the super class or interface, check results on return
 415   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 416                                                     class_loader,
 417                                                     protection_domain,
 418                                                     THREAD);
 419 
 420   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 421   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 422   // or error. GC used to walk the placeholder table as strong roots.
 423   // The instanceKlass is kept alive because the class loader is on the stack,
 424   // which keeps the loader_data alive, as well as all instanceKlasses in
 425   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 426   {
 427     MutexLocker mu(SystemDictionary_lock, THREAD);
 428     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 429     SystemDictionary_lock->notify_all();
 430   }
 431   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 432     // can null superk
 433     superk = handle_resolution_exception(class_name, true, superk, THREAD);
 434   }
 435 
 436   return superk;
 437 }
 438 
 439 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 440                                                   Handle class_loader,
 441                                                   Handle protection_domain,
 442                                                   TRAPS) {
 443   if(!has_checkPackageAccess()) return;
 444 
 445   // Now we have to call back to java to check if the initating class has access
 446   JavaValue result(T_VOID);
 447   LogTarget(Debug, protectiondomain) lt;
 448   if (lt.is_enabled()) {
 449     ResourceMark rm;
 450     // Print out trace information
 451     LogStream ls(lt);
 452     ls.print_cr("Checking package access");
 453     ls.print("class loader: "); class_loader()->print_value_on(&ls);
 454     ls.print(" protection domain: "); protection_domain()->print_value_on(&ls);
 455     ls.print(" loading: "); klass->print_value_on(&ls);
 456     ls.cr();
 457   }
 458 
 459   // This handle and the class_loader handle passed in keeps this class from
 460   // being unloaded through several GC points.
 461   // The class_loader handle passed in is the initiating loader.
 462   Handle mirror(THREAD, klass->java_mirror());
 463 
 464   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 465   JavaCalls::call_special(&result,
 466                          class_loader,
 467                          system_loader,
 468                          vmSymbols::checkPackageAccess_name(),
 469                          vmSymbols::class_protectiondomain_signature(),
 470                          mirror,
 471                          protection_domain,
 472                          THREAD);
 473 
 474   if (HAS_PENDING_EXCEPTION) {
 475     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 476   } else {
 477    log_debug(protectiondomain)("granted");
 478   }
 479 
 480   if (HAS_PENDING_EXCEPTION) return;
 481 
 482   // If no exception has been thrown, we have validated the protection domain
 483   // Insert the protection domain of the initiating class into the set.
 484   {
 485     ClassLoaderData* loader_data = class_loader_data(class_loader);
 486     Dictionary* dictionary = loader_data->dictionary();
 487 
 488     Symbol*  kn = klass->name();
 489     unsigned int d_hash = dictionary->compute_hash(kn);
 490     int d_index = dictionary->hash_to_index(d_hash);
 491 
 492     MutexLocker mu(SystemDictionary_lock, THREAD);

 493     dictionary->add_protection_domain(d_index, d_hash, klass,
 494                                       protection_domain, THREAD);
 495   }
 496 }
 497 
 498 // We only get here if this thread finds that another thread
 499 // has already claimed the placeholder token for the current operation,
 500 // but that other thread either never owned or gave up the
 501 // object lock
 502 // Waits on SystemDictionary_lock to indicate placeholder table updated
 503 // On return, caller must recheck placeholder table state
 504 //
 505 // We only get here if
 506 //  1) custom classLoader, i.e. not bootstrap classloader
 507 //  2) UnsyncloadClass not set
 508 //  3) custom classLoader has broken the class loader objectLock
 509 //     so another thread got here in parallel
 510 //
 511 // lockObject must be held.
 512 // Complicated dance due to lock ordering:
 513 // Must first release the classloader object lock to
 514 // allow initial definer to complete the class definition
 515 // and to avoid deadlock
 516 // Reclaim classloader lock object with same original recursion count
 517 // Must release SystemDictionary_lock after notify, since
 518 // class loader lock must be claimed before SystemDictionary_lock
 519 // to prevent deadlocks
 520 //
 521 // The notify allows applications that did an untimed wait() on
 522 // the classloader object lock to not hang.
 523 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 524   assert_lock_strong(SystemDictionary_lock);
 525 
 526   bool calledholdinglock
 527       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 528   assert(calledholdinglock,"must hold lock for notify");
 529   assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 530   ObjectSynchronizer::notifyall(lockObject, THREAD);
 531   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 532   SystemDictionary_lock->wait();
 533   SystemDictionary_lock->unlock();
 534   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 535   SystemDictionary_lock->lock();
 536 }
 537 
 538 // If the class in is in the placeholder table, class loading is in progress
 539 // For cases where the application changes threads to load classes, it
 540 // is critical to ClassCircularity detection that we try loading
 541 // the superclass on the same thread internally, so we do parallel
 542 // super class loading here.
 543 // This also is critical in cases where the original thread gets stalled
 544 // even in non-circularity situations.
 545 // Note: must call resolve_super_or_fail even if null super -
 546 // to force placeholder entry creation for this class for circularity detection
 547 // Caller must check for pending exception
 548 // Returns non-null Klass* if other thread has completed load
 549 // and we are done,
 550 // If return null Klass* and no pending exception, the caller must load the class
 551 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 552     Symbol* name, Symbol* superclassname, Handle class_loader,
 553     Handle protection_domain, Handle lockObject, TRAPS) {
 554 
 555   ClassLoaderData* loader_data = class_loader_data(class_loader);
 556   Dictionary* dictionary = loader_data->dictionary();
 557   unsigned int d_hash = dictionary->compute_hash(name);
 558   int d_index = dictionary->hash_to_index(d_hash);
 559   unsigned int p_hash = placeholders()->compute_hash(name);
 560   int p_index = placeholders()->hash_to_index(p_hash);
 561 
 562   // superk is not used, resolve_super called for circularity check only
 563   // This code is reached in two situations. One if this thread
 564   // is loading the same class twice (e.g. ClassCircularity, or
 565   // java.lang.instrument).
 566   // The second is if another thread started the resolve_super first
 567   // and has not yet finished.
 568   // In both cases the original caller will clean up the placeholder
 569   // entry on error.
 570   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 571                                                           superclassname,
 572                                                           class_loader,
 573                                                           protection_domain,
 574                                                           true,
 575                                                           CHECK_NULL);
 576 
 577   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 578   // Serial class loaders and bootstrap classloader do wait for superclass loads
 579  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 580     MutexLocker mu(SystemDictionary_lock, THREAD);
 581     // Check if classloading completed while we were loading superclass or waiting
 582     return find_class(d_index, d_hash, name, dictionary);
 583   }
 584 
 585   // must loop to both handle other placeholder updates
 586   // and spurious notifications
 587   bool super_load_in_progress = true;
 588   PlaceholderEntry* placeholder;
 589   while (super_load_in_progress) {
 590     MutexLocker mu(SystemDictionary_lock, THREAD);
 591     // Check if classloading completed while we were loading superclass or waiting
 592     InstanceKlass* check = find_class(d_index, d_hash, name, dictionary);
 593     if (check != NULL) {
 594       // Klass is already loaded, so just return it
 595       return check;
 596     } else {
 597       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 598       if (placeholder && placeholder->super_load_in_progress() ){
 599         // Before UnsyncloadClass:
 600         // We only get here if the application has released the
 601         // classloader lock when another thread was in the middle of loading a
 602         // superclass/superinterface for this class, and now
 603         // this thread is also trying to load this class.
 604         // To minimize surprises, the first thread that started to
 605         // load a class should be the one to complete the loading
 606         // with the classfile it initially expected.
 607         // This logic has the current thread wait once it has done
 608         // all the superclass/superinterface loading it can, until
 609         // the original thread completes the class loading or fails
 610         // If it completes we will use the resulting InstanceKlass
 611         // which we will find below in the systemDictionary.
 612         // We also get here for parallel bootstrap classloader
 613         if (class_loader.is_null()) {
 614           SystemDictionary_lock->wait();
 615         } else {
 616           double_lock_wait(lockObject, THREAD);
 617         }
 618       } else {
 619         // If not in SD and not in PH, other thread's load must have failed
 620         super_load_in_progress = false;
 621       }
 622     }
 623   }
 624   return NULL;
 625 }
 626 
 627 static void post_class_load_event(EventClassLoad* event,
 628                                   const InstanceKlass* k,
 629                                   const ClassLoaderData* init_cld) {
 630 #if INCLUDE_TRACE
 631   assert(event != NULL, "invariant");
 632   assert(k != NULL, "invariant");
 633   if (event->should_commit()) {
 634     event->set_loadedClass(k);
 635     event->set_definingClassLoader(k->class_loader_data());
 636     event->set_initiatingClassLoader(init_cld);
 637     event->commit();
 638   }
 639 #endif // INCLUDE_TRACE
 640 }
 641 
 642 static void class_define_event(InstanceKlass* k,
 643                                const ClassLoaderData* def_cld) {
 644 #if INCLUDE_TRACE
 645   EventClassDefine event;
 646   if (event.should_commit()) {
 647     event.set_definedClass(k);
 648     event.set_definingClassLoader(def_cld);
 649     event.commit();
 650   }
 651 #endif // INCLUDE_TRACE
 652 }
 653 
 654 // Be careful when modifying this code: once you have run
 655 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 656 // you need to find_and_remove it before returning.
 657 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 658 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 659                                                         Handle class_loader,
 660                                                         Handle protection_domain,
 661                                                         TRAPS) {
 662   assert(name != NULL && !FieldType::is_array(name) &&
 663          !FieldType::is_obj(name), "invalid class name");
 664 
 665   EventClassLoad class_load_start_event;
 666 
 667   HandleMark hm(THREAD);
 668 
 669   // Fix for 4474172; see evaluation for more details
 670   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 671   ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
 672   Dictionary* dictionary = loader_data->dictionary();

 673 
 674   // Do lookup to see if class already exist and the protection domain
 675   // has the right access
 676   // This call uses find which checks protection domain already matches
 677   // All subsequent calls use find_class, and set has_loaded_class so that
 678   // before we return a result we call out to java to check for valid protection domain
 679   // to allow returning the Klass* and add it to the pd_set if it is valid
 680   unsigned int d_hash = dictionary->compute_hash(name);
 681   int d_index = dictionary->hash_to_index(d_hash);
 682   Klass* probe = dictionary->find(d_index, d_hash, name, protection_domain);
 683   if (probe != NULL) return probe;
 684 
 685 
 686   // Non-bootstrap class loaders will call out to class loader and
 687   // define via jvm/jni_DefineClass which will acquire the
 688   // class loader object lock to protect against multiple threads
 689   // defining the class in parallel by accident.
 690   // This lock must be acquired here so the waiter will find
 691   // any successful result in the SystemDictionary and not attempt
 692   // the define
 693   // ParallelCapable Classloaders and the bootstrap classloader,
 694   // or all classloaders with UnsyncloadClass do not acquire lock here
 695   bool DoObjectLock = true;
 696   if (is_parallelCapable(class_loader)) {
 697     DoObjectLock = false;
 698   }
 699 
 700   unsigned int p_hash = placeholders()->compute_hash(name);
 701   int p_index = placeholders()->hash_to_index(p_hash);
 702 
 703   // Class is not in SystemDictionary so we have to do loading.
 704   // Make sure we are synchronized on the class loader before we proceed
 705   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 706   check_loader_lock_contention(lockObject, THREAD);
 707   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 708 
 709   // Check again (after locking) if class already exist in SystemDictionary
 710   bool class_has_been_loaded   = false;
 711   bool super_load_in_progress  = false;
 712   bool havesupername = false;
 713   InstanceKlass* k = NULL;
 714   PlaceholderEntry* placeholder;
 715   Symbol* superclassname = NULL;
 716 
 717   {
 718     MutexLocker mu(SystemDictionary_lock, THREAD);
 719     InstanceKlass* check = find_class(d_index, d_hash, name, dictionary);
 720     if (check != NULL) {
 721       // Klass is already loaded, so just return it
 722       class_has_been_loaded = true;
 723       k = check;
 724     } else {
 725       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 726       if (placeholder && placeholder->super_load_in_progress()) {
 727          super_load_in_progress = true;
 728          if (placeholder->havesupername() == true) {
 729            superclassname = placeholder->supername();
 730            havesupername = true;
 731          }
 732       }
 733     }
 734   }
 735 
 736   // If the class is in the placeholder table, class loading is in progress
 737   if (super_load_in_progress && havesupername==true) {
 738     k = handle_parallel_super_load(name,
 739                                    superclassname,
 740                                    class_loader,
 741                                    protection_domain,
 742                                    lockObject, THREAD);
 743     if (HAS_PENDING_EXCEPTION) {
 744       return NULL;
 745     }
 746     if (k != NULL) {
 747       class_has_been_loaded = true;
 748     }
 749   }
 750 
 751   bool throw_circularity_error = false;
 752   if (!class_has_been_loaded) {
 753     bool load_instance_added = false;
 754 
 755     // add placeholder entry to record loading instance class
 756     // Five cases:
 757     // All cases need to prevent modifying bootclasssearchpath
 758     // in parallel with a classload of same classname
 759     // Redefineclasses uses existence of the placeholder for the duration
 760     // of the class load to prevent concurrent redefinition of not completely
 761     // defined classes.
 762     // case 1. traditional classloaders that rely on the classloader object lock
 763     //   - no other need for LOAD_INSTANCE
 764     // case 2. traditional classloaders that break the classloader object lock
 765     //    as a deadlock workaround. Detection of this case requires that
 766     //    this check is done while holding the classloader object lock,
 767     //    and that lock is still held when calling classloader's loadClass.
 768     //    For these classloaders, we ensure that the first requestor
 769     //    completes the load and other requestors wait for completion.
 770     // case 3. UnsyncloadClass - don't use objectLocker
 771     //    With this flag, we allow parallel classloading of a
 772     //    class/classloader pair
 773     // case4. Bootstrap classloader - don't own objectLocker
 774     //    This classloader supports parallelism at the classloader level,
 775     //    but only allows a single load of a class/classloader pair.
 776     //    No performance benefit and no deadlock issues.
 777     // case 5. parallelCapable user level classloaders - without objectLocker
 778     //    Allow parallel classloading of a class/classloader pair
 779 
 780     {
 781       MutexLocker mu(SystemDictionary_lock, THREAD);
 782       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 783         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 784         if (oldprobe) {
 785           // only need check_seen_thread once, not on each loop
 786           // 6341374 java/lang/Instrument with -Xcomp
 787           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 788             throw_circularity_error = true;
 789           } else {
 790             // case 1: traditional: should never see load_in_progress.
 791             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 792 
 793               // case 4: bootstrap classloader: prevent futile classloading,
 794               // wait on first requestor
 795               if (class_loader.is_null()) {
 796                 SystemDictionary_lock->wait();
 797               } else {
 798               // case 2: traditional with broken classloader lock. wait on first
 799               // requestor.
 800                 double_lock_wait(lockObject, THREAD);
 801               }
 802               // Check if classloading completed while we were waiting
 803               InstanceKlass* check = find_class(d_index, d_hash, name, dictionary);
 804               if (check != NULL) {
 805                 // Klass is already loaded, so just return it
 806                 k = check;
 807                 class_has_been_loaded = true;
 808               }
 809               // check if other thread failed to load and cleaned up
 810               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 811             }
 812           }
 813         }
 814       }
 815       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 816       // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
 817       // LOAD_INSTANCE in parallel
 818 
 819       if (!throw_circularity_error && !class_has_been_loaded) {
 820         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 821         load_instance_added = true;
 822         // For class loaders that do not acquire the classloader object lock,
 823         // if they did not catch another thread holding LOAD_INSTANCE,
 824         // need a check analogous to the acquire ObjectLocker/find_class
 825         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 826         // one final check if the load has already completed
 827         // class loaders holding the ObjectLock shouldn't find the class here
 828         InstanceKlass* check = find_class(d_index, d_hash, name, dictionary);
 829         if (check != NULL) {
 830         // Klass is already loaded, so return it after checking/adding protection domain
 831           k = check;
 832           class_has_been_loaded = true;
 833         }
 834       }
 835     }
 836 
 837     // must throw error outside of owning lock
 838     if (throw_circularity_error) {
 839       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 840       ResourceMark rm(THREAD);
 841       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 842     }
 843 
 844     if (!class_has_been_loaded) {
 845 
 846       // Do actual loading
 847       k = load_instance_class(name, class_loader, THREAD);
 848 
 849       // For UnsyncloadClass only
 850       // If they got a linkageError, check if a parallel class load succeeded.
 851       // If it did, then for bytecode resolution the specification requires
 852       // that we return the same result we did for the other thread, i.e. the
 853       // successfully loaded InstanceKlass
 854       // Should not get here for classloaders that support parallelism
 855       // with the new cleaner mechanism, even with AllowParallelDefineClass
 856       // Bootstrap goes through here to allow for an extra guarantee check
 857       if (UnsyncloadClass || (class_loader.is_null())) {
 858         if (k == NULL && HAS_PENDING_EXCEPTION
 859           && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
 860           MutexLocker mu(SystemDictionary_lock, THREAD);
 861           InstanceKlass* check = find_class(d_index, d_hash, name, dictionary);
 862           if (check != NULL) {
 863             // Klass is already loaded, so just use it
 864             k = check;
 865             CLEAR_PENDING_EXCEPTION;
 866             guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
 867           }
 868         }
 869       }
 870 
 871       // If everything was OK (no exceptions, no null return value), and
 872       // class_loader is NOT the defining loader, do a little more bookkeeping.
 873       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 874         k->class_loader() != class_loader()) {
 875 
 876         check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
 877 
 878         // Need to check for a PENDING_EXCEPTION again; check_constraints
 879         // can throw and doesn't use the CHECK macro.
 880         if (!HAS_PENDING_EXCEPTION) {
 881           { // Grabbing the Compile_lock prevents systemDictionary updates
 882             // during compilations.
 883             MutexLocker mu(Compile_lock, THREAD);
 884             update_dictionary(d_index, d_hash, p_index, p_hash,
 885               k, class_loader, THREAD);
 886           }
 887 
 888           if (JvmtiExport::should_post_class_load()) {
 889             Thread *thread = THREAD;
 890             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 891             JvmtiExport::post_class_load((JavaThread *) thread, k);
 892           }
 893         }
 894       }
 895     } // load_instance_class
 896 
 897     if (load_instance_added == true) {
 898       // clean up placeholder entries for LOAD_INSTANCE success or error
 899       // This brackets the SystemDictionary updates for both defining
 900       // and initiating loaders
 901       MutexLocker mu(SystemDictionary_lock, THREAD);
 902       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 903       SystemDictionary_lock->notify_all();
 904     }
 905   }
 906 
 907   if (HAS_PENDING_EXCEPTION || k == NULL) {
 908     return NULL;
 909   }
 910 
 911   post_class_load_event(&class_load_start_event, k, loader_data);
 912 
 913 #ifdef ASSERT
 914   {
 915     ClassLoaderData* loader_data = k->class_loader_data();
 916     MutexLocker mu(SystemDictionary_lock, THREAD);
 917     Klass* kk = find_class(name, loader_data);
 918     assert(kk == k, "should be present in dictionary");
 919   }
 920 #endif
 921 
 922   // return if the protection domain in NULL
 923   if (protection_domain() == NULL) return k;
 924 
 925   // Check the protection domain has the right access
 926   if (dictionary->is_valid_protection_domain(d_index, d_hash, name,
 927                                              protection_domain)) {
 928     return k;
 929   }
 930 
 931   // Verify protection domain. If it fails an exception is thrown
 932   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 933 
 934   return k;
 935 }
 936 
 937 
 938 // This routine does not lock the system dictionary.
 939 //
 940 // Since readers don't hold a lock, we must make sure that system
 941 // dictionary entries are only removed at a safepoint (when only one
 942 // thread is running), and are added to in a safe way (all links must
 943 // be updated in an MT-safe manner).
 944 //
 945 // Callers should be aware that an entry could be added just after
 946 // _dictionary->bucket(index) is read here, so the caller will not see
 947 // the new entry.
 948 
 949 Klass* SystemDictionary::find(Symbol* class_name,
 950                               Handle class_loader,
 951                               Handle protection_domain,
 952                               TRAPS) {
 953 
 954   // The result of this call should be consistent with the result
 955   // of the call to resolve_instance_class_or_null().
 956   // See evaluation 6790209 and 4474172 for more details.
 957   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 958   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 959 
 960   if (loader_data == NULL) {
 961     // If the ClassLoaderData has not been setup,
 962     // then the class loader has no entries in the dictionary.
 963     return NULL;
 964   }
 965 
 966   Dictionary* dictionary = loader_data->dictionary();
 967   unsigned int d_hash = dictionary->compute_hash(class_name);
 968   int d_index = dictionary->hash_to_index(d_hash);
 969   return dictionary->find(d_index, d_hash, class_name,
 970                           protection_domain);
 971 }
 972 
 973 
 974 // Look for a loaded instance or array klass by name.  Do not do any loading.
 975 // return NULL in case of error.
 976 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 977                                                       Handle class_loader,
 978                                                       Handle protection_domain,
 979                                                       TRAPS) {
 980   Klass* k = NULL;
 981   assert(class_name != NULL, "class name must be non NULL");
 982 
 983   if (FieldType::is_array(class_name)) {
 984     // The name refers to an array.  Parse the name.
 985     // dimension and object_key in FieldArrayInfo are assigned as a
 986     // side-effect of this call
 987     FieldArrayInfo fd;
 988     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 989     if (t != T_OBJECT) {
 990       k = Universe::typeArrayKlassObj(t);
 991     } else {
 992       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 993     }
 994     if (k != NULL) {
 995       k = k->array_klass_or_null(fd.dimension());
 996     }
 997   } else {
 998     k = find(class_name, class_loader, protection_domain, THREAD);
 999   }
1000   return k;
1001 }
1002 
1003 // Note: this method is much like resolve_from_stream, but
1004 // does not publish the classes via the SystemDictionary.
1005 // Handles unsafe_DefineAnonymousClass and redefineclasses
1006 // RedefinedClasses do not add to the class hierarchy
1007 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
1008                                               Handle class_loader,
1009                                               Handle protection_domain,
1010                                               ClassFileStream* st,
1011                                               const InstanceKlass* host_klass,
1012                                               GrowableArray<Handle>* cp_patches,
1013                                               TRAPS) {
1014 
1015   EventClassLoad class_load_start_event;
1016 
1017   ClassLoaderData* loader_data;
1018   if (host_klass != NULL) {
1019     // Create a new CLD for anonymous class, that uses the same class loader
1020     // as the host_klass
1021     guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1022     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1023   } else {
1024     loader_data = ClassLoaderData::class_loader_data(class_loader());
1025   }
1026 
1027   assert(st != NULL, "invariant");
1028   assert(st->need_verify(), "invariant");
1029 
1030   // Parse stream and create a klass.
1031   // Note that we do this even though this klass might
1032   // already be present in the SystemDictionary, otherwise we would not
1033   // throw potential ClassFormatErrors.
1034 
1035   InstanceKlass* k = KlassFactory::create_from_stream(st,
1036                                                       class_name,
1037                                                       loader_data,
1038                                                       protection_domain,
1039                                                       host_klass,
1040                                                       cp_patches,
1041                                                       CHECK_NULL);
1042 
1043   if (host_klass != NULL && k != NULL) {
1044     // If it's anonymous, initialize it now, since nobody else will.
1045 
1046     {
1047       MutexLocker mu_r(Compile_lock, THREAD);
1048 
1049       // Add to class hierarchy, initialize vtables, and do possible
1050       // deoptimizations.
1051       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1052 
1053       // But, do not add to dictionary.
1054 
1055       // compiled code dependencies need to be validated anyway
1056       notice_modification();
1057     }
1058 
1059     // Rewrite and patch constant pool here.
1060     k->link_class(CHECK_NULL);
1061     if (cp_patches != NULL) {
1062       k->constants()->patch_resolved_references(cp_patches);
1063     }
1064     k->eager_initialize(CHECK_NULL);
1065 
1066     // notify jvmti
1067     if (JvmtiExport::should_post_class_load()) {
1068         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1069         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1070     }
1071 
1072     post_class_load_event(&class_load_start_event, k, loader_data);
1073   }
1074   assert(host_klass != NULL || NULL == cp_patches,
1075          "cp_patches only found with host_klass");
1076 
1077   return k;
1078 }
1079 
1080 // Add a klass to the system from a stream (called by jni_DefineClass and
1081 // JVM_DefineClass).
1082 // Note: class_name can be NULL. In that case we do not know the name of
1083 // the class until we have parsed the stream.
1084 
1085 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1086                                                      Handle class_loader,
1087                                                      Handle protection_domain,
1088                                                      ClassFileStream* st,
1089                                                      TRAPS) {
1090 #if INCLUDE_CDS
1091   ResourceMark rm(THREAD);
1092   if (DumpSharedSpaces && !class_loader.is_null() &&
1093       !ArgumentsExt::using_AppCDS() && strcmp(class_name->as_C_string(), "Unnamed") != 0) {
1094     // If AppCDS is not enabled, don't define the class at dump time (except for the "Unnamed"
1095     // class, which is used by MethodHandles).
1096     THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
1097   }
1098 #endif
1099 
1100   HandleMark hm(THREAD);
1101 
1102   // Classloaders that support parallelism, e.g. bootstrap classloader,
1103   // or all classloaders with UnsyncloadClass do not acquire lock here
1104   bool DoObjectLock = true;
1105   if (is_parallelCapable(class_loader)) {
1106     DoObjectLock = false;
1107   }
1108 
1109   ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1110 
1111   // Make sure we are synchronized on the class loader before we proceed
1112   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1113   check_loader_lock_contention(lockObject, THREAD);
1114   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1115 
1116   assert(st != NULL, "invariant");
1117 
1118   // Parse the stream and create a klass.
1119   // Note that we do this even though this klass might
1120   // already be present in the SystemDictionary, otherwise we would not
1121   // throw potential ClassFormatErrors.
1122  InstanceKlass* k = NULL;
1123 
1124 #if INCLUDE_CDS
1125   if (!DumpSharedSpaces) {
1126     k = SystemDictionaryShared::lookup_from_stream(class_name,
1127                                                    class_loader,
1128                                                    protection_domain,
1129                                                    st,
1130                                                    CHECK_NULL);
1131   }
1132 #endif
1133 
1134   if (k == NULL) {
1135     if (st->buffer() == NULL) {
1136       return NULL;
1137     }
1138     k = KlassFactory::create_from_stream(st,
1139                                          class_name,
1140                                          loader_data,
1141                                          protection_domain,
1142                                          NULL, // host_klass
1143                                          NULL, // cp_patches
1144                                          CHECK_NULL);
1145   }
1146 
1147   assert(k != NULL, "no klass created");
1148   Symbol* h_name = k->name();
1149   assert(class_name == NULL || class_name == h_name, "name mismatch");
1150 
1151   // Add class just loaded
1152   // If a class loader supports parallel classloading handle parallel define requests
1153   // find_or_define_instance_class may return a different InstanceKlass
1154   if (is_parallelCapable(class_loader)) {
1155     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1156     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1157       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1158       assert(defined_k != NULL, "Should have a klass if there's no exception");
1159       loader_data->add_to_deallocate_list(k);
1160       k = defined_k;
1161     }
1162   } else {
1163     define_instance_class(k, THREAD);
1164   }
1165 
1166   // If defining the class throws an exception register 'k' for cleanup.
1167   if (HAS_PENDING_EXCEPTION) {
1168     assert(k != NULL, "Must have an instance klass here!");
1169     loader_data->add_to_deallocate_list(k);
1170     return NULL;
1171   }
1172 
1173   // Make sure we have an entry in the SystemDictionary on success
1174   debug_only( {
1175     MutexLocker mu(SystemDictionary_lock, THREAD);
1176 
1177     Klass* check = find_class(h_name, k->class_loader_data());
1178     assert(check == k, "should be present in the dictionary");
1179   } );
1180 
1181   return k;
1182 }
1183 
1184 #if INCLUDE_CDS
1185 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1186                                              int number_of_entries) {
1187   assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>),
1188          "bad shared dictionary size.");
1189   _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(),
1190                                       _shared_dictionary_size, t, number_of_entries);
1191 }
1192 
1193 
1194 // If there is a shared dictionary, then find the entry for the
1195 // given shared system class, if any.
1196 
1197 InstanceKlass* SystemDictionary::find_shared_class(Symbol* class_name) {
1198   if (shared_dictionary() != NULL) {
1199     unsigned int d_hash = shared_dictionary()->compute_hash(class_name);
1200     int d_index = shared_dictionary()->hash_to_index(d_hash);
1201 
1202     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1203   } else {
1204     return NULL;
1205   }
1206 }
1207 
1208 
1209 // Load a class from the shared spaces (found through the shared system
1210 // dictionary).  Force the superclass and all interfaces to be loaded.
1211 // Update the class definition to include sibling classes and no
1212 // subclasses (yet).  [Classes in the shared space are not part of the
1213 // object hierarchy until loaded.]
1214 
1215 InstanceKlass* SystemDictionary::load_shared_class(
1216                  Symbol* class_name, Handle class_loader, TRAPS) {
1217   InstanceKlass* ik = find_shared_class(class_name);
1218   // Make sure we only return the boot class for the NULL classloader.
1219   if (ik != NULL &&
1220       ik->is_shared_boot_class() && class_loader.is_null()) {
1221     Handle protection_domain;
1222     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1223   }
1224   return NULL;
1225 }
1226 
1227 // Check if a shared class can be loaded by the specific classloader:
1228 //
1229 // NULL classloader:
1230 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1231 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1232 //     be defined in an unnamed module.
1233 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1234                                                InstanceKlass* ik,
1235                                                Handle class_loader, TRAPS) {
1236   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1237          "Cannot use sharing if java.base is patched");
1238   ResourceMark rm;
1239   int path_index = ik->shared_classpath_index();
1240   ClassLoaderData* loader_data = class_loader_data(class_loader);
1241   if (path_index < 0) {
1242     // path_index < 0 indicates that the class is intended for a custom loader
1243     // and should not be loaded by boot/platform/app loaders
1244     if (loader_data->is_builtin_class_loader_data()) {
1245       return false;
1246     } else {
1247       return true;
1248     }
1249   }
1250   SharedClassPathEntry* ent =
1251             (SharedClassPathEntry*)FileMapInfo::shared_classpath(path_index);
1252   if (!Universe::is_module_initialized()) {
1253     assert(ent != NULL && ent->is_modules_image(),
1254            "Loading non-bootstrap classes before the module system is initialized");
1255     assert(class_loader.is_null(), "sanity");
1256     return true;
1257   }
1258   // Get the pkg_entry from the classloader
1259   TempNewSymbol pkg_name = NULL;
1260   PackageEntry* pkg_entry = NULL;
1261   ModuleEntry* mod_entry = NULL;
1262   const char* pkg_string = NULL;
1263   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1264   if (pkg_name != NULL) {
1265     pkg_string = pkg_name->as_C_string();
1266     if (loader_data != NULL) {
1267       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1268     }
1269     if (pkg_entry != NULL) {
1270       mod_entry = pkg_entry->module();
1271     }
1272   }
1273 
1274   // If the archived class is from a module that has been patched at runtime,
1275   // the class cannot be loaded from the archive.
1276   if (mod_entry != NULL && mod_entry->is_patched()) {
1277     return false;
1278   }
1279 
1280   if (class_loader.is_null()) {
1281     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1282     // The NULL classloader can load archived class originated from the
1283     // "modules" jimage and the -Xbootclasspath/a. For class from the
1284     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1285     // by the NULL classloader.
1286     if (mod_entry != NULL) {
1287       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1288       // ModuleEntry's location agrees with the archived class' origination.
1289       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1290         return true; // Module class from the "module" jimage
1291       }
1292     }
1293 
1294     // If the archived class is not from the "module" jimage, the class can be
1295     // loaded by the NULL classloader if
1296     //
1297     // 1. the class is from the unamed package
1298     // 2. or, the class is not from a module defined in the NULL classloader
1299     // 3. or, the class is from an unamed module
1300     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1301       // the class is from the -Xbootclasspath/a
1302       if (pkg_string == NULL ||
1303           pkg_entry == NULL ||
1304           pkg_entry->in_unnamed_module()) {
1305         assert(mod_entry == NULL ||
1306                mod_entry == loader_data->unnamed_module(),
1307                "the unnamed module is not defined in the classloader");
1308         return true;
1309       }
1310     }
1311     return false;
1312   } else {
1313     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1314               ik, class_loader, pkg_string, pkg_name,
1315               pkg_entry, mod_entry, CHECK_(false));
1316     return res;
1317   }
1318 }
1319 
1320 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1321                                                    Handle class_loader,
1322                                                    Handle protection_domain, TRAPS) {
1323 
1324   if (ik != NULL) {
1325     Symbol* class_name = ik->name();
1326 
1327     bool visible = is_shared_class_visible(
1328                             class_name, ik, class_loader, CHECK_NULL);
1329     if (!visible) {
1330       return NULL;
1331     }
1332 
1333     // Resolve the superclass and interfaces. They must be the same
1334     // as in dump time, because the layout of <ik> depends on
1335     // the specific layout of ik->super() and ik->local_interfaces().
1336     //
1337     // If unexpected superclass or interfaces are found, we cannot
1338     // load <ik> from the shared archive.
1339 
1340     if (ik->super() != NULL) {
1341       Symbol*  cn = ik->super()->name();
1342       Klass *s = resolve_super_or_fail(class_name, cn,
1343                                        class_loader, protection_domain, true, CHECK_NULL);
1344       if (s != ik->super()) {
1345         // The dynamically resolved super class is not the same as the one we used during dump time,
1346         // so we cannot use ik.
1347         return NULL;
1348       } else {
1349         assert(s->is_shared(), "must be");
1350       }
1351     }
1352 
1353     Array<Klass*>* interfaces = ik->local_interfaces();
1354     int num_interfaces = interfaces->length();
1355     for (int index = 0; index < num_interfaces; index++) {
1356       Klass* k = interfaces->at(index);
1357       Symbol*  name  = k->name();
1358       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1359       if (k != i) {
1360         // The dynamically resolved interface class is not the same as the one we used during dump time,
1361         // so we cannot use ik.
1362         return NULL;
1363       } else {
1364         assert(i->is_shared(), "must be");
1365       }
1366     }
1367 
1368     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1369         ik, class_name, class_loader, protection_domain, CHECK_NULL);
1370     if (new_ik != NULL) {
1371       // The class is changed by CFLH. Return the new class. The shared class is
1372       // not used.
1373       return new_ik;
1374     }
1375 
1376     // Adjust methods to recover missing data.  They need addresses for
1377     // interpreter entry points and their default native method address
1378     // must be reset.
1379 
1380     // Updating methods must be done under a lock so multiple
1381     // threads don't update these in parallel
1382     //
1383     // Shared classes are all currently loaded by either the bootstrap or
1384     // internal parallel class loaders, so this will never cause a deadlock
1385     // on a custom class loader lock.
1386 
1387     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1388     {
1389       HandleMark hm(THREAD);
1390       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1391       check_loader_lock_contention(lockObject, THREAD);
1392       ObjectLocker ol(lockObject, THREAD, true);
1393       // prohibited package check assumes all classes loaded from archive call
1394       // restore_unshareable_info which calls ik->set_package()
1395       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1396     }
1397 
1398     ik->print_class_load_logging(loader_data, NULL, NULL);
1399 
1400     // For boot loader, ensure that GetSystemPackage knows that a class in this
1401     // package was loaded.
1402     if (class_loader.is_null()) {
1403       int path_index = ik->shared_classpath_index();
1404       ResourceMark rm;
1405       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1406     }
1407 
1408     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1409       // Only dump the classes that can be stored into CDS archive
1410       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1411         ResourceMark rm(THREAD);
1412         classlist_file->print_cr("%s", ik->name()->as_C_string());
1413         classlist_file->flush();
1414       }
1415     }
1416 
1417     // notify a class loaded from shared object
1418     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1419   }
1420 
1421   ik->set_has_passed_fingerprint_check(false);
1422   if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1423     uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1424     uint64_t cds_fp = ik->get_stored_fingerprint();
1425     if (aot_fp != 0 && aot_fp == cds_fp) {
1426       // This class matches with a class saved in an AOT library
1427       ik->set_has_passed_fingerprint_check(true);
1428     } else {
1429       ResourceMark rm;
1430       log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1431     }
1432   }
1433   return ik;
1434 }
1435 
1436 void SystemDictionary::clear_invoke_method_table() {
1437   SymbolPropertyEntry* spe = NULL;
1438   for (int index = 0; index < _invoke_method_table->table_size(); index++) {
1439     SymbolPropertyEntry* p = _invoke_method_table->bucket(index);
1440     while (p != NULL) {
1441       spe = p;
1442       p = p->next();
1443       _invoke_method_table->free_entry(spe);
1444     }
1445   }
1446 }
1447 #endif // INCLUDE_CDS
1448 
1449 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1450 
1451   if (class_loader.is_null()) {
1452     ResourceMark rm;
1453     PackageEntry* pkg_entry = NULL;
1454     bool search_only_bootloader_append = false;
1455     ClassLoaderData *loader_data = class_loader_data(class_loader);
1456 
1457     // Find the package in the boot loader's package entry table.
1458     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1459     if (pkg_name != NULL) {
1460       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1461     }
1462 
1463     // Prior to attempting to load the class, enforce the boot loader's
1464     // visibility boundaries.
1465     if (!Universe::is_module_initialized()) {
1466       // During bootstrapping, prior to module initialization, any
1467       // class attempting to be loaded must be checked against the
1468       // java.base packages in the boot loader's PackageEntryTable.
1469       // No class outside of java.base is allowed to be loaded during
1470       // this bootstrapping window.
1471       if (!DumpSharedSpaces) {
1472         if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1473           // Class is either in the unnamed package or in
1474           // a named package within the unnamed module.  Either
1475           // case is outside of java.base, do not attempt to
1476           // load the class post java.base definition.  If
1477           // java.base has not been defined, let the class load
1478           // and its package will be checked later by
1479           // ModuleEntryTable::verify_javabase_packages.
1480           if (ModuleEntryTable::javabase_defined()) {
1481             return NULL;
1482           }
1483         } else {
1484           // Check that the class' package is defined within java.base.
1485           ModuleEntry* mod_entry = pkg_entry->module();
1486           Symbol* mod_entry_name = mod_entry->name();
1487           if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1488             return NULL;
1489           }
1490         }
1491       }
1492     } else {
1493       // After the module system has been initialized, check if the class'
1494       // package is in a module defined to the boot loader.
1495       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1496         // Class is either in the unnamed package, in a named package
1497         // within a module not defined to the boot loader or in a
1498         // a named package within the unnamed module.  In all cases,
1499         // limit visibility to search for the class only in the boot
1500         // loader's append path.
1501         search_only_bootloader_append = true;
1502       }
1503     }
1504 
1505     // Prior to bootstrapping's module initialization, never load a class outside
1506     // of the boot loader's module path
1507     assert(Universe::is_module_initialized() || DumpSharedSpaces ||
1508            !search_only_bootloader_append,
1509            "Attempt to load a class outside of boot loader's module path");
1510 
1511     // Search the shared system dictionary for classes preloaded into the
1512     // shared spaces.
1513     InstanceKlass* k = NULL;
1514     {
1515 #if INCLUDE_CDS
1516       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1517       k = load_shared_class(class_name, class_loader, THREAD);
1518 #endif
1519     }
1520 
1521     if (k == NULL) {
1522       // Use VM class loader
1523       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1524       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1525     }
1526 
1527     // find_or_define_instance_class may return a different InstanceKlass
1528     if (k != NULL) {
1529       InstanceKlass* defined_k =
1530         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1531       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1532         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1533         assert(defined_k != NULL, "Should have a klass if there's no exception");
1534         loader_data->add_to_deallocate_list(k);
1535         k = defined_k;
1536       } else if (HAS_PENDING_EXCEPTION) {
1537         loader_data->add_to_deallocate_list(k);
1538         return NULL;
1539       }
1540     }
1541     return k;
1542   } else {
1543     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1544     ResourceMark rm(THREAD);
1545 
1546     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1547     JavaThread* jt = (JavaThread*) THREAD;
1548 
1549     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1550                                ClassLoader::perf_app_classload_selftime(),
1551                                ClassLoader::perf_app_classload_count(),
1552                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1553                                jt->get_thread_stat()->perf_timers_addr(),
1554                                PerfClassTraceTime::CLASS_LOAD);
1555 
1556     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1557     // Translate to external class name format, i.e., convert '/' chars to '.'
1558     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1559 
1560     JavaValue result(T_OBJECT);
1561 
1562     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1563 
1564     // Call public unsynchronized loadClass(String) directly for all class loaders
1565     // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1566     // acquire a class-name based lock rather than the class loader object lock.
1567     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1568     // so the call to loadClassInternal() was not required.
1569     //
1570     // UnsyncloadClass flag means both call loadClass(String) and do
1571     // not acquire the class loader lock even for class loaders that are
1572     // not parallelCapable. This was a risky transitional
1573     // flag for diagnostic purposes only. It is risky to call
1574     // custom class loaders without synchronization.
1575     // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1576     // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1577     // Do NOT assume this will be supported in future releases.
1578     //
1579     // Added MustCallLoadClassInternal in case we discover in the field
1580     // a customer that counts on this call
1581     if (MustCallLoadClassInternal && has_loadClassInternal()) {
1582       JavaCalls::call_special(&result,
1583                               class_loader,
1584                               spec_klass,
1585                               vmSymbols::loadClassInternal_name(),
1586                               vmSymbols::string_class_signature(),
1587                               string,
1588                               CHECK_NULL);
1589     } else {
1590       JavaCalls::call_virtual(&result,
1591                               class_loader,
1592                               spec_klass,
1593                               vmSymbols::loadClass_name(),
1594                               vmSymbols::string_class_signature(),
1595                               string,
1596                               CHECK_NULL);
1597     }
1598 
1599     assert(result.get_type() == T_OBJECT, "just checking");
1600     oop obj = (oop) result.get_jobject();
1601 
1602     // Primitive classes return null since forName() can not be
1603     // used to obtain any of the Class objects representing primitives or void
1604     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1605       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1606       // For user defined Java class loaders, check that the name returned is
1607       // the same as that requested.  This check is done for the bootstrap
1608       // loader when parsing the class file.
1609       if (class_name == k->name()) {
1610         return k;
1611       }
1612     }
1613     // Class is not found or has the wrong name, return NULL
1614     return NULL;
1615   }
1616 }
1617 
1618 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1619 
1620   HandleMark hm(THREAD);
1621   ClassLoaderData* loader_data = k->class_loader_data();
1622   Handle class_loader_h(THREAD, loader_data->class_loader());
1623 
1624  // for bootstrap and other parallel classloaders don't acquire lock,
1625  // use placeholder token
1626  // If a parallelCapable class loader calls define_instance_class instead of
1627  // find_or_define_instance_class to get here, we have a timing
1628  // hole with systemDictionary updates and check_constraints
1629  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1630     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1631          compute_loader_lock_object(class_loader_h, THREAD)),
1632          "define called without lock");
1633   }
1634 
1635   // Check class-loading constraints. Throw exception if violation is detected.
1636   // Grabs and releases SystemDictionary_lock
1637   // The check_constraints/find_class call and update_dictionary sequence
1638   // must be "atomic" for a specific class/classloader pair so we never
1639   // define two different instanceKlasses for that class/classloader pair.
1640   // Existing classloaders will call define_instance_class with the
1641   // classloader lock held
1642   // Parallel classloaders will call find_or_define_instance_class
1643   // which will require a token to perform the define class
1644   Symbol*  name_h = k->name();
1645   Dictionary* dictionary = loader_data->dictionary();
1646   unsigned int d_hash = dictionary->compute_hash(name_h);
1647   int d_index = dictionary->hash_to_index(d_hash);
1648   check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1649 
1650   // Register class just loaded with class loader (placed in Vector)
1651   // Note we do this before updating the dictionary, as this can
1652   // fail with an OutOfMemoryError (if it does, we will *not* put this
1653   // class in the dictionary and will not update the class hierarchy).
1654   // JVMTI FollowReferences needs to find the classes this way.
1655   if (k->class_loader() != NULL) {
1656     methodHandle m(THREAD, Universe::loader_addClass_method());
1657     JavaValue result(T_VOID);
1658     JavaCallArguments args(class_loader_h);
1659     args.push_oop(Handle(THREAD, k->java_mirror()));
1660     JavaCalls::call(&result, m, &args, CHECK);
1661   }
1662 
1663   // Add the new class. We need recompile lock during update of CHA.
1664   {
1665     unsigned int p_hash = placeholders()->compute_hash(name_h);
1666     int p_index = placeholders()->hash_to_index(p_hash);
1667 
1668     MutexLocker mu_r(Compile_lock, THREAD);
1669 
1670     // Add to class hierarchy, initialize vtables, and do possible
1671     // deoptimizations.
1672     add_to_hierarchy(k, CHECK); // No exception, but can block
1673 
1674     // Add to systemDictionary - so other classes can see it.
1675     // Grabs and releases SystemDictionary_lock
1676     update_dictionary(d_index, d_hash, p_index, p_hash,
1677                       k, class_loader_h, THREAD);
1678   }
1679   k->eager_initialize(THREAD);
1680 
1681   // notify jvmti
1682   if (JvmtiExport::should_post_class_load()) {
1683       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1684       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1685 
1686   }
1687   class_define_event(k, loader_data);
1688 }
1689 
1690 // Support parallel classloading
1691 // All parallel class loaders, including bootstrap classloader
1692 // lock a placeholder entry for this class/class_loader pair
1693 // to allow parallel defines of different classes for this class loader
1694 // With AllowParallelDefine flag==true, in case they do not synchronize around
1695 // FindLoadedClass/DefineClass, calls, we check for parallel
1696 // loading for them, wait if a defineClass is in progress
1697 // and return the initial requestor's results
1698 // This flag does not apply to the bootstrap classloader.
1699 // With AllowParallelDefine flag==false, call through to define_instance_class
1700 // which will throw LinkageError: duplicate class definition.
1701 // False is the requested default.
1702 // For better performance, the class loaders should synchronize
1703 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1704 // potentially waste time reading and parsing the bytestream.
1705 // Note: VM callers should ensure consistency of k/class_name,class_loader
1706 // Be careful when modifying this code: once you have run
1707 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1708 // you need to find_and_remove it before returning.
1709 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1710 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1711                                                                InstanceKlass* k, TRAPS) {
1712 
1713   Symbol*  name_h = k->name(); // passed in class_name may be null
1714   ClassLoaderData* loader_data = class_loader_data(class_loader);
1715   Dictionary* dictionary = loader_data->dictionary();
1716 
1717   unsigned int d_hash = dictionary->compute_hash(name_h);
1718   int d_index = dictionary->hash_to_index(d_hash);
1719 
1720   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1721   unsigned int p_hash = placeholders()->compute_hash(name_h);
1722   int p_index = placeholders()->hash_to_index(p_hash);
1723   PlaceholderEntry* probe;
1724 
1725   {
1726     MutexLocker mu(SystemDictionary_lock, THREAD);
1727     // First check if class already defined
1728     if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1729       InstanceKlass* check = find_class(d_index, d_hash, name_h, dictionary);
1730       if (check != NULL) {
1731         return check;
1732       }
1733     }
1734 
1735     // Acquire define token for this class/classloader
1736     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1737     // Wait if another thread defining in parallel
1738     // All threads wait - even those that will throw duplicate class: otherwise
1739     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1740     // if other thread has not finished updating dictionary
1741     while (probe->definer() != NULL) {
1742       SystemDictionary_lock->wait();
1743     }
1744     // Only special cases allow parallel defines and can use other thread's results
1745     // Other cases fall through, and may run into duplicate defines
1746     // caught by finding an entry in the SystemDictionary
1747     if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1748         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1749         SystemDictionary_lock->notify_all();
1750 #ifdef ASSERT
1751         InstanceKlass* check = find_class(d_index, d_hash, name_h, dictionary);
1752         assert(check != NULL, "definer missed recording success");
1753 #endif
1754         return probe->instance_klass();
1755     } else {
1756       // This thread will define the class (even if earlier thread tried and had an error)
1757       probe->set_definer(THREAD);
1758     }
1759   }
1760 
1761   define_instance_class(k, THREAD);
1762 
1763   Handle linkage_exception = Handle(); // null handle
1764 
1765   // definer must notify any waiting threads
1766   {
1767     MutexLocker mu(SystemDictionary_lock, THREAD);
1768     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1769     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1770     if (probe != NULL) {
1771       if (HAS_PENDING_EXCEPTION) {
1772         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1773         CLEAR_PENDING_EXCEPTION;
1774       } else {
1775         probe->set_instance_klass(k);
1776       }
1777       probe->set_definer(NULL);
1778       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1779       SystemDictionary_lock->notify_all();
1780     }
1781   }
1782 
1783   // Can't throw exception while holding lock due to rank ordering
1784   if (linkage_exception() != NULL) {
1785     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1786   }
1787 
1788   return k;
1789 }
1790 
1791 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1792   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1793   if (class_loader.is_null()) {
1794     return Handle(THREAD, _system_loader_lock_obj);
1795   } else {
1796     return class_loader;
1797   }
1798 }
1799 
1800 // This method is added to check how often we have to wait to grab loader
1801 // lock. The results are being recorded in the performance counters defined in
1802 // ClassLoader::_sync_systemLoaderLockContentionRate and
1803 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1804 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1805   if (!UsePerfData) {
1806     return;
1807   }
1808 
1809   assert(!loader_lock.is_null(), "NULL lock object");
1810 
1811   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1812       == ObjectSynchronizer::owner_other) {
1813     // contention will likely happen, so increment the corresponding
1814     // contention counter.
1815     if (loader_lock() == _system_loader_lock_obj) {
1816       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1817     } else {
1818       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1819     }
1820   }
1821 }
1822 
1823 // ----------------------------------------------------------------------------
1824 // Lookup
1825 
1826 InstanceKlass* SystemDictionary::find_class(int index, unsigned int hash,
1827                                             Symbol* class_name,
1828                                             Dictionary* dictionary) {
1829   assert_locked_or_safepoint(SystemDictionary_lock);

1830   return dictionary->find_class(index, hash, class_name);
1831 }
1832 
1833 
1834 // Basic find on classes in the midst of being loaded
1835 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1836                                            ClassLoaderData* loader_data) {
1837   assert_locked_or_safepoint(SystemDictionary_lock);
1838   unsigned int p_hash = placeholders()->compute_hash(class_name);
1839   int p_index = placeholders()->hash_to_index(p_hash);
1840   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1841 }
1842 
1843 
1844 // Used for assertions and verification only
1845 // Precalculating the hash and index is an optimization because there are many lookups
1846 // before adding the class.
1847 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1848   assert_locked_or_safepoint(SystemDictionary_lock);
1849   #ifndef ASSERT
1850   guarantee(VerifyBeforeGC      ||
1851             VerifyDuringGC      ||
1852             VerifyBeforeExit    ||
1853             VerifyDuringStartup ||
1854             VerifyAfterGC, "too expensive");
1855   #endif
1856 
1857   Dictionary* dictionary = loader_data->dictionary();
1858   unsigned int d_hash = dictionary->compute_hash(class_name);
1859   int d_index = dictionary->hash_to_index(d_hash);
1860   return find_class(d_index, d_hash, class_name, dictionary);
1861 }
1862 
1863 
1864 // ----------------------------------------------------------------------------
1865 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1866 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1867 // before a new class is used.
1868 
1869 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1870   assert(k != NULL, "just checking");
1871   assert_locked_or_safepoint(Compile_lock);
1872 
1873   // Link into hierachy. Make sure the vtables are initialized before linking into
1874   k->append_to_sibling_list();                    // add to superklass/sibling list
1875   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1876   k->set_init_state(InstanceKlass::loaded);
1877   // Now flush all code that depended on old class hierarchy.
1878   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1879   // Also, first reinitialize vtable because it may have gotten out of synch
1880   // while the new class wasn't connected to the class hierarchy.
1881   CodeCache::flush_dependents_on(k);
1882 }
1883 
1884 // ----------------------------------------------------------------------------
1885 // GC support
1886 
1887 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1888   roots_oops_do(blk, NULL);
1889 }
1890 
1891 
1892 #ifdef ASSERT
1893 class VerifySDReachableAndLiveClosure : public OopClosure {
1894 private:
1895   BoolObjectClosure* _is_alive;
1896 
1897   template <class T> void do_oop_work(T* p) {
1898     oop obj = oopDesc::load_decode_heap_oop(p);
1899     guarantee(_is_alive->do_object_b(obj), "Oop in protection domain cache table must be live");
1900   }
1901 
1902 public:
1903   VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1904 
1905   virtual void do_oop(oop* p)       { do_oop_work(p); }
1906   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1907 };
1908 #endif
1909 
1910 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1911 // Note: anonymous classes are not in the SD.
1912 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1913                                     GCTimer* gc_timer,
1914                                     bool do_cleaning) {
1915 
1916 
1917   bool unloading_occurred;
1918   {
1919     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1920 
1921     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1922     unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1923                                                             do_cleaning);
1924   }
1925 
1926   if (unloading_occurred) {
1927     GCTraceTime(Debug, gc, phases) t("Dictionary", gc_timer);
1928     constraints()->purge_loader_constraints();
1929     resolution_errors()->purge_resolution_errors();
1930   }
1931 
1932   {
1933     GCTraceTime(Debug, gc, phases) t("ProtectionDomainCacheTable", gc_timer);
1934     // Oops referenced by the protection domain cache table may get unreachable independently
1935     // of the class loader (eg. cached protection domain oops). So we need to
1936     // explicitly unlink them here.
1937     _pd_cache_table->unlink(is_alive);
1938 
1939 #ifdef ASSERT
1940     VerifySDReachableAndLiveClosure cl(is_alive);
1941     _pd_cache_table->oops_do(&cl);
1942 #endif
1943   }
1944 
1945   if (do_cleaning) {
1946     GCTraceTime(Debug, gc, phases) t("ResolvedMethodTable", gc_timer);
1947     ResolvedMethodTable::unlink(is_alive);
1948   }
1949 
1950   return unloading_occurred;
1951 }
1952 
1953 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1954   strong->do_oop(&_java_system_loader);
1955   strong->do_oop(&_java_platform_loader);
1956   strong->do_oop(&_system_loader_lock_obj);
1957   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1958 
1959   // Do strong roots marking if the closures are the same.
1960   if (strong == weak || !ClassUnloading) {
1961     // Only the protection domain oops contain references into the heap. Iterate
1962     // over all of them.
1963     _pd_cache_table->oops_do(strong);
1964   } else {
1965    if (weak != NULL) {
1966      _pd_cache_table->oops_do(weak);
1967    }
1968   }
1969 
1970   // Visit extra methods
1971   invoke_method_table()->oops_do(strong);
1972 
1973   if (weak != NULL) {
1974     ResolvedMethodTable::oops_do(weak);
1975   }
1976 }
1977 
1978 void SystemDictionary::oops_do(OopClosure* f) {
1979   f->do_oop(&_java_system_loader);
1980   f->do_oop(&_java_platform_loader);
1981   f->do_oop(&_system_loader_lock_obj);
1982   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1983 
1984   // Only the protection domain oops contain references into the heap. Iterate
1985   // over all of them.
1986   _pd_cache_table->oops_do(f);
1987 
1988   // Visit extra methods
1989   invoke_method_table()->oops_do(f);
1990 
1991   ResolvedMethodTable::oops_do(f);
1992 }
1993 
1994 // CDS: scan and relocate all classes in the system dictionary.
1995 void SystemDictionary::classes_do(MetaspaceClosure* it) {
1996   ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(it);
1997 }
1998 
1999 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
2000 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
2001   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
2002     it->push(well_known_klass_addr((WKID)id));
2003   }
2004 }
2005 
2006 void SystemDictionary::methods_do(void f(Method*)) {
2007   // Walk methods in loaded classes
2008   ClassLoaderDataGraph::methods_do(f);
2009   // Walk method handle intrinsics
2010   invoke_method_table()->methods_do(f);
2011 }
2012 
2013 class RemoveClassesClosure : public CLDClosure {
2014   public:
2015     void do_cld(ClassLoaderData* cld) {
2016       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
2017         cld->dictionary()->remove_classes_in_error_state();
2018       }
2019     }
2020 };
2021 
2022 void SystemDictionary::remove_classes_in_error_state() {
2023   ClassLoaderData::the_null_class_loader_data()->dictionary()->remove_classes_in_error_state();
2024   RemoveClassesClosure rcc;
2025   ClassLoaderDataGraph::cld_do(&rcc);
2026 }
2027 
2028 // ----------------------------------------------------------------------------
2029 // Lazily load klasses
2030 
2031 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
2032   // if multiple threads calling this function, only one thread will load
2033   // the class.  The other threads will find the loaded version once the
2034   // class is loaded.
2035   Klass* aos = _abstract_ownable_synchronizer_klass;
2036   if (aos == NULL) {
2037     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
2038     // Force a fence to prevent any read before the write completes
2039     OrderAccess::fence();
2040     _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
2041   }
2042 }
2043 
2044 // ----------------------------------------------------------------------------
2045 // Initialization
2046 
2047 void SystemDictionary::initialize(TRAPS) {
2048   // Allocate arrays
2049   _placeholders        = new PlaceholderTable(_placeholder_table_size);
2050   _number_of_modifications = 0;
2051   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
2052   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
2053   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
2054   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
2055 
2056   // Allocate private object used as system class loader lock
2057   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
2058   // Initialize basic classes
2059   initialize_preloaded_classes(CHECK);
2060 }
2061 
2062 // Compact table of directions on the initialization of klasses:
2063 static const short wk_init_info[] = {
2064   #define WK_KLASS_INIT_INFO(name, symbol, option) \
2065     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
2066           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
2067       | (int)SystemDictionary::option ),
2068   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
2069   #undef WK_KLASS_INIT_INFO
2070   0
2071 };
2072 
2073 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
2074   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2075   int  info = wk_init_info[id - FIRST_WKID];
2076   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
2077   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
2078   InstanceKlass** klassp = &_well_known_klasses[id];
2079 
2080   bool must_load;
2081 #if INCLUDE_JVMCI
2082   if (EnableJVMCI) {
2083     // If JVMCI is enabled we require its classes to be found.
2084     must_load = (init_opt < SystemDictionary::Opt) || (init_opt == SystemDictionary::Jvmci);
2085   } else
2086 #endif
2087   {
2088     must_load = (init_opt < SystemDictionary::Opt);
2089   }
2090 
2091   if ((*klassp) == NULL) {
2092     Klass* k;
2093     if (must_load) {
2094       k = resolve_or_fail(symbol, true, CHECK_0); // load required class
2095     } else {
2096       k = resolve_or_null(symbol,       CHECK_0); // load optional klass
2097     }
2098     (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
2099   }
2100   return ((*klassp) != NULL);
2101 }
2102 
2103 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
2104   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
2105   for (int id = (int)start_id; id < (int)limit_id; id++) {
2106     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2107     int info = wk_init_info[id - FIRST_WKID];
2108     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
2109     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
2110 
2111     initialize_wk_klass((WKID)id, opt, CHECK);
2112   }
2113 
2114   // move the starting value forward to the limit:
2115   start_id = limit_id;
2116 }
2117 
2118 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
2119   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
2120 
2121   // Create the ModuleEntry for java.base.  This call needs to be done here,
2122   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
2123   ClassLoader::classLoader_init2(CHECK);
2124 
2125   // Preload commonly used klasses
2126   WKID scan = FIRST_WKID;
2127   // first do Object, then String, Class
2128 #if INCLUDE_CDS
2129   if (UseSharedSpaces) {
2130     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
2131     // Initialize the constant pool for the Object_class
2132     Object_klass()->constants()->restore_unshareable_info(CHECK);
2133     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2134   } else
2135 #endif
2136   {
2137     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2138   }
2139 
2140   // Calculate offsets for String and Class classes since they are loaded and
2141   // can be used after this point.
2142   java_lang_String::compute_offsets();
2143   java_lang_Class::compute_offsets();
2144 
2145   // Fixup mirrors for classes loaded before java.lang.Class.
2146   // These calls iterate over the objects currently in the perm gen
2147   // so calling them at this point is matters (not before when there
2148   // are fewer objects and not later after there are more objects
2149   // in the perm gen.
2150   Universe::initialize_basic_type_mirrors(CHECK);
2151   Universe::fixup_mirrors(CHECK);
2152 
2153   // do a bunch more:
2154   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2155 
2156   // Preload ref klasses and set reference types
2157   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2158   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2159 
2160   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2161   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2162   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2163   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2164   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2165 
2166   // JSR 292 classes
2167   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2168   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2169   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
2170   initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
2171   initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
2172 
2173   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2174   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2175   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2176   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2177   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2178   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2179   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2180   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2181   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2182   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2183 
2184   { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2185     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2186     _has_loadClassInternal = (method != NULL);
2187   }
2188   { // Compute whether we should use checkPackageAccess or NOT
2189     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2190     _has_checkPackageAccess = (method != NULL);
2191   }
2192 }
2193 
2194 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2195 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2196 BasicType SystemDictionary::box_klass_type(Klass* k) {
2197   assert(k != NULL, "");
2198   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2199     if (_box_klasses[i] == k)
2200       return (BasicType)i;
2201   }
2202   return T_OBJECT;
2203 }
2204 
2205 // Constraints on class loaders. The details of the algorithm can be
2206 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2207 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2208 // that the dictionary needs to maintain a set of contraints that
2209 // must be satisfied by all classes in the dictionary.
2210 // if defining is true, then LinkageError if already in dictionary
2211 // if initiating loader, then ok if InstanceKlass matches existing entry
2212 
2213 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2214                                          InstanceKlass* k,
2215                                          Handle class_loader, bool defining,
2216                                          TRAPS) {
2217   const char *linkage_error1 = NULL;
2218   const char *linkage_error2 = NULL;
2219   {
2220     Symbol*  name  = k->name();
2221     ClassLoaderData *loader_data = class_loader_data(class_loader);
2222 
2223     MutexLocker mu(SystemDictionary_lock, THREAD);
2224 
2225     InstanceKlass* check = find_class(d_index, d_hash, name, loader_data->dictionary());
2226     if (check != NULL) {
2227       // if different InstanceKlass - duplicate class definition,
2228       // else - ok, class loaded by a different thread in parallel,
2229       // we should only have found it if it was done loading and ok to use
2230       // dictionary only holds instance classes, placeholders
2231       // also holds array classes
2232 
2233       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2234       if ((defining == true) || (k != check)) {
2235         linkage_error1 = "loader (instance of ";
2236         linkage_error2 = "): attempted duplicate class definition for name: \"";
2237       } else {
2238         return;
2239       }
2240     }
2241 
2242 #ifdef ASSERT
2243     Symbol* ph_check = find_placeholder(name, loader_data);
2244     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2245 #endif
2246 
2247     if (linkage_error1 == NULL) {
2248       if (constraints()->check_or_update(k, class_loader, name) == false) {
2249         linkage_error1 = "loader constraint violation: loader (instance of ";
2250         linkage_error2 = ") previously initiated loading for a different type with name \"";
2251       }
2252     }
2253   }
2254 
2255   // Throw error now if needed (cannot throw while holding
2256   // SystemDictionary_lock because of rank ordering)
2257 
2258   if (linkage_error1) {
2259     ResourceMark rm(THREAD);
2260     const char* class_loader_name = loader_name(class_loader());
2261     char* type_name = k->name()->as_C_string();
2262     size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2263       strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2264     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2265     jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2266     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2267   }
2268 }
2269 
2270 
2271 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2272 // have been called.
2273 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2274                                          int p_index, unsigned int p_hash,
2275                                          InstanceKlass* k,
2276                                          Handle class_loader,
2277                                          TRAPS) {
2278   // Compile_lock prevents systemDictionary updates during compilations
2279   assert_locked_or_safepoint(Compile_lock);
2280   Symbol*  name  = k->name();
2281   ClassLoaderData *loader_data = class_loader_data(class_loader);
2282 
2283   {
2284     MutexLocker mu1(SystemDictionary_lock, THREAD);
2285 
2286     // See whether biased locking is enabled and if so set it for this
2287     // klass.
2288     // Note that this must be done past the last potential blocking
2289     // point / safepoint. We enable biased locking lazily using a
2290     // VM_Operation to iterate the SystemDictionary and installing the
2291     // biasable mark word into each InstanceKlass's prototype header.
2292     // To avoid race conditions where we accidentally miss enabling the
2293     // optimization for one class in the process of being added to the
2294     // dictionary, we must not safepoint after the test of
2295     // BiasedLocking::enabled().
2296     if (UseBiasedLocking && BiasedLocking::enabled()) {
2297       // Set biased locking bit for all loaded classes; it will be
2298       // cleared if revocation occurs too often for this type
2299       // NOTE that we must only do this when the class is initally
2300       // defined, not each time it is referenced from a new class loader
2301       if (k->class_loader() == class_loader()) {
2302         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2303       }
2304     }
2305 
2306     // Make a new dictionary entry.
2307     Dictionary* dictionary = loader_data->dictionary();
2308     InstanceKlass* sd_check = find_class(d_index, d_hash, name, dictionary);
2309     if (sd_check == NULL) {
2310       dictionary->add_klass(d_index, d_hash, name, k);
2311       notice_modification();
2312     }
2313   #ifdef ASSERT
2314     sd_check = find_class(d_index, d_hash, name, dictionary);
2315     assert (sd_check != NULL, "should have entry in dictionary");
2316     // Note: there may be a placeholder entry: for circularity testing
2317     // or for parallel defines
2318   #endif
2319     SystemDictionary_lock->notify_all();
2320   }
2321 }
2322 
2323 
2324 // Try to find a class name using the loader constraints.  The
2325 // loader constraints might know about a class that isn't fully loaded
2326 // yet and these will be ignored.
2327 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2328                     Symbol* class_name, Handle class_loader, TRAPS) {
2329 
2330   // First see if it has been loaded directly.
2331   // Force the protection domain to be null.  (This removes protection checks.)
2332   Handle no_protection_domain;
2333   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2334                                               no_protection_domain, CHECK_NULL);
2335   if (klass != NULL)
2336     return klass;
2337 
2338   // Now look to see if it has been loaded elsewhere, and is subject to
2339   // a loader constraint that would require this loader to return the
2340   // klass that is already loaded.
2341   if (FieldType::is_array(class_name)) {
2342     // For array classes, their Klass*s are not kept in the
2343     // constraint table. The element Klass*s are.
2344     FieldArrayInfo fd;
2345     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2346     if (t != T_OBJECT) {
2347       klass = Universe::typeArrayKlassObj(t);
2348     } else {
2349       MutexLocker mu(SystemDictionary_lock, THREAD);
2350       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2351     }
2352     // If element class already loaded, allocate array klass
2353     if (klass != NULL) {
2354       klass = klass->array_klass_or_null(fd.dimension());
2355     }
2356   } else {
2357     MutexLocker mu(SystemDictionary_lock, THREAD);
2358     // Non-array classes are easy: simply check the constraint table.
2359     klass = constraints()->find_constrained_klass(class_name, class_loader);
2360   }
2361 
2362   return klass;
2363 }
2364 
2365 
2366 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2367                                              Handle class_loader1,
2368                                              Handle class_loader2,
2369                                              Thread* THREAD) {
2370   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2371   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2372 
2373   Symbol* constraint_name = NULL;
2374   if (!FieldType::is_array(class_name)) {
2375     constraint_name = class_name;
2376   } else {
2377     // For array classes, their Klass*s are not kept in the
2378     // constraint table. The element classes are.
2379     FieldArrayInfo fd;
2380     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2381     // primitive types always pass
2382     if (t != T_OBJECT) {
2383       return true;
2384     } else {
2385       constraint_name = fd.object_key();
2386     }
2387   }
2388 
2389   Dictionary* dictionary1 = loader_data1->dictionary();
2390   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2391   int d_index1 = dictionary1->hash_to_index(d_hash1);
2392 
2393   Dictionary* dictionary2 = loader_data2->dictionary();
2394   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2395   int d_index2 = dictionary2->hash_to_index(d_hash2);
2396 
2397   {
2398     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2399     InstanceKlass* klass1 = find_class(d_index1, d_hash1, constraint_name, dictionary1);
2400     InstanceKlass* klass2 = find_class(d_index2, d_hash2, constraint_name, dictionary2);
2401     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2402                                     klass2, class_loader2);
2403   }
2404 }
2405 
2406 // Add entry to resolution error table to record the error when the first
2407 // attempt to resolve a reference to a class has failed.
2408 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2409                                             Symbol* error, Symbol* message) {
2410   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2411   int index = resolution_errors()->hash_to_index(hash);
2412   {
2413     MutexLocker ml(SystemDictionary_lock, Thread::current());
2414     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2415   }
2416 }
2417 
2418 // Delete a resolution error for RedefineClasses for a constant pool is going away
2419 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2420   resolution_errors()->delete_entry(pool);
2421 }
2422 
2423 // Lookup resolution error table. Returns error if found, otherwise NULL.
2424 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2425                                                 Symbol** message) {
2426   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2427   int index = resolution_errors()->hash_to_index(hash);
2428   {
2429     MutexLocker ml(SystemDictionary_lock, Thread::current());
2430     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2431     if (entry != NULL) {
2432       *message = entry->message();
2433       return entry->error();
2434     } else {
2435       return NULL;
2436     }
2437   }
2438 }
2439 
2440 
2441 // Signature constraints ensure that callers and callees agree about
2442 // the meaning of type names in their signatures.  This routine is the
2443 // intake for constraints.  It collects them from several places:
2444 //
2445 //  * LinkResolver::resolve_method (if check_access is true) requires
2446 //    that the resolving class (the caller) and the defining class of
2447 //    the resolved method (the callee) agree on each type in the
2448 //    method's signature.
2449 //
2450 //  * LinkResolver::resolve_interface_method performs exactly the same
2451 //    checks.
2452 //
2453 //  * LinkResolver::resolve_field requires that the constant pool
2454 //    attempting to link to a field agree with the field's defining
2455 //    class about the type of the field signature.
2456 //
2457 //  * klassVtable::initialize_vtable requires that, when a class
2458 //    overrides a vtable entry allocated by a superclass, that the
2459 //    overriding method (i.e., the callee) agree with the superclass
2460 //    on each type in the method's signature.
2461 //
2462 //  * klassItable::initialize_itable requires that, when a class fills
2463 //    in its itables, for each non-abstract method installed in an
2464 //    itable, the method (i.e., the callee) agree with the interface
2465 //    on each type in the method's signature.
2466 //
2467 // All those methods have a boolean (check_access, checkconstraints)
2468 // which turns off the checks.  This is used from specialized contexts
2469 // such as bootstrapping, dumping, and debugging.
2470 //
2471 // No direct constraint is placed between the class and its
2472 // supertypes.  Constraints are only placed along linked relations
2473 // between callers and callees.  When a method overrides or implements
2474 // an abstract method in a supertype (superclass or interface), the
2475 // constraints are placed as if the supertype were the caller to the
2476 // overriding method.  (This works well, since callers to the
2477 // supertype have already established agreement between themselves and
2478 // the supertype.)  As a result of all this, a class can disagree with
2479 // its supertype about the meaning of a type name, as long as that
2480 // class neither calls a relevant method of the supertype, nor is
2481 // called (perhaps via an override) from the supertype.
2482 //
2483 //
2484 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2485 //
2486 // Make sure all class components (including arrays) in the given
2487 // signature will be resolved to the same class in both loaders.
2488 // Returns the name of the type that failed a loader constraint check, or
2489 // NULL if no constraint failed.  No exception except OOME is thrown.
2490 // Arrays are not added to the loader constraint table, their elements are.
2491 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2492                                                Handle loader1, Handle loader2,
2493                                                bool is_method, TRAPS)  {
2494   // Nothing to do if loaders are the same.
2495   if (loader1() == loader2()) {
2496     return NULL;
2497   }
2498 
2499   SignatureStream sig_strm(signature, is_method);
2500   while (!sig_strm.is_done()) {
2501     if (sig_strm.is_object()) {
2502       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2503       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2504         return sig;
2505       }
2506     }
2507     sig_strm.next();
2508   }
2509   return NULL;
2510 }
2511 
2512 
2513 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2514                                                             Symbol* signature,
2515                                                             TRAPS) {
2516   methodHandle empty;
2517   assert(MethodHandles::is_signature_polymorphic(iid) &&
2518          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2519          iid != vmIntrinsics::_invokeGeneric,
2520          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2521 
2522   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2523   int          index = invoke_method_table()->hash_to_index(hash);
2524   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2525   methodHandle m;
2526   if (spe == NULL || spe->method() == NULL) {
2527     spe = NULL;
2528     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2529     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2530     if (!Arguments::is_interpreter_only()) {
2531       // Generate a compiled form of the MH intrinsic.
2532       AdapterHandlerLibrary::create_native_wrapper(m);
2533       // Check if have the compiled code.
2534       if (!m->has_compiled_code()) {
2535         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2536                    "Out of space in CodeCache for method handle intrinsic", empty);
2537       }
2538     }
2539     // Now grab the lock.  We might have to throw away the new method,
2540     // if a racing thread has managed to install one at the same time.
2541     {
2542       MutexLocker ml(SystemDictionary_lock, THREAD);
2543       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2544       if (spe == NULL)
2545         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2546       if (spe->method() == NULL)
2547         spe->set_method(m());
2548     }
2549   }
2550 
2551   assert(spe != NULL && spe->method() != NULL, "");
2552   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2553          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2554          "MH intrinsic invariant");
2555   return spe->method();
2556 }
2557 
2558 // Helper for unpacking the return value from linkMethod and linkCallSite.
2559 static methodHandle unpack_method_and_appendix(Handle mname,
2560                                                Klass* accessing_klass,
2561                                                objArrayHandle appendix_box,
2562                                                Handle* appendix_result,
2563                                                TRAPS) {
2564   methodHandle empty;
2565   if (mname.not_null()) {
2566     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2567     if (m != NULL) {
2568       oop appendix = appendix_box->obj_at(0);
2569       if (TraceMethodHandles) {
2570     #ifndef PRODUCT
2571         ttyLocker ttyl;
2572         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2573         m->print();
2574         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2575         tty->cr();
2576     #endif //PRODUCT
2577       }
2578       (*appendix_result) = Handle(THREAD, appendix);
2579       // the target is stored in the cpCache and if a reference to this
2580       // MethodName is dropped we need a way to make sure the
2581       // class_loader containing this method is kept alive.
2582       // FIXME: the appendix might also preserve this dependency.
2583       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2584       this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2585       return methodHandle(THREAD, m);
2586     }
2587   }
2588   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2589   return empty;
2590 }
2591 
2592 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2593                                                           Symbol* name,
2594                                                           Symbol* signature,
2595                                                           Klass* accessing_klass,
2596                                                           Handle *appendix_result,
2597                                                           Handle *method_type_result,
2598                                                           TRAPS) {
2599   methodHandle empty;
2600   assert(THREAD->can_call_java() ,"");
2601   Handle method_type =
2602     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2603 
2604   int ref_kind = JVM_REF_invokeVirtual;
2605   oop name_oop = StringTable::intern(name, CHECK_(empty));
2606   Handle name_str (THREAD, name_oop);
2607   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2608   assert(appendix_box->obj_at(0) == NULL, "");
2609 
2610   // This should not happen.  JDK code should take care of that.
2611   if (accessing_klass == NULL || method_type.is_null()) {
2612     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2613   }
2614 
2615   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2616   JavaCallArguments args;
2617   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2618   args.push_int(ref_kind);
2619   args.push_oop(Handle(THREAD, klass->java_mirror()));
2620   args.push_oop(name_str);
2621   args.push_oop(method_type);
2622   args.push_oop(appendix_box);
2623   JavaValue result(T_OBJECT);
2624   JavaCalls::call_static(&result,
2625                          SystemDictionary::MethodHandleNatives_klass(),
2626                          vmSymbols::linkMethod_name(),
2627                          vmSymbols::linkMethod_signature(),
2628                          &args, CHECK_(empty));
2629   Handle mname(THREAD, (oop) result.get_jobject());
2630   (*method_type_result) = method_type;
2631   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2632 }
2633 
2634 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2635 // We must ensure that all class loaders everywhere will reach this class, for any client.
2636 // This is a safe bet for public classes in java.lang, such as Object and String.
2637 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2638 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2639 static bool is_always_visible_class(oop mirror) {
2640   Klass* klass = java_lang_Class::as_Klass(mirror);
2641   if (klass->is_objArray_klass()) {
2642     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2643   }
2644   if (klass->is_typeArray_klass()) {
2645     return true; // primitive array
2646   }
2647   assert(klass->is_instance_klass(), "%s", klass->external_name());
2648   return klass->is_public() &&
2649          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2650           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2651 }
2652 
2653 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2654 // signature, as interpreted relative to the given class loader.
2655 // Because of class loader constraints, all method handle usage must be
2656 // consistent with this loader.
2657 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2658                                                  Klass* accessing_klass,
2659                                                  TRAPS) {
2660   Handle empty;
2661   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2662   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2663   int          index = invoke_method_table()->hash_to_index(hash);
2664   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2665   if (spe != NULL && spe->method_type() != NULL) {
2666     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2667     return Handle(THREAD, spe->method_type());
2668   } else if (!THREAD->can_call_java()) {
2669     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2670     return Handle();  // do not attempt from within compiler, unless it was cached
2671   }
2672 
2673   Handle class_loader, protection_domain;
2674   if (accessing_klass != NULL) {
2675     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2676     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2677   }
2678   bool can_be_cached = true;
2679   int npts = ArgumentCount(signature).size();
2680   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2681   int arg = 0;
2682   Handle rt; // the return type from the signature
2683   ResourceMark rm(THREAD);
2684   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2685     oop mirror = NULL;
2686     if (can_be_cached) {
2687       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2688       mirror = ss.as_java_mirror(Handle(), Handle(),
2689                                  SignatureStream::ReturnNull, CHECK_(empty));
2690       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2691         // Fall back to accessing_klass context.
2692         can_be_cached = false;
2693       }
2694     }
2695     if (!can_be_cached) {
2696       // Resolve, throwing a real error if it doesn't work.
2697       mirror = ss.as_java_mirror(class_loader, protection_domain,
2698                                  SignatureStream::NCDFError, CHECK_(empty));
2699     }
2700     assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2701     if (ss.at_return_type())
2702       rt = Handle(THREAD, mirror);
2703     else
2704       pts->obj_at_put(arg++, mirror);
2705 
2706     // Check accessibility.
2707     if (ss.is_object() && accessing_klass != NULL) {
2708       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2709       mirror = NULL;  // safety
2710       // Emulate ConstantPool::verify_constant_pool_resolve.
2711       if (sel_klass->is_objArray_klass())
2712         sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2713       if (sel_klass->is_instance_klass()) {
2714         LinkResolver::check_klass_accessability(accessing_klass, sel_klass, CHECK_(empty));
2715       }
2716     }
2717   }
2718   assert(arg == npts, "");
2719 
2720   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2721   JavaCallArguments args(Handle(THREAD, rt()));
2722   args.push_oop(pts);
2723   JavaValue result(T_OBJECT);
2724   JavaCalls::call_static(&result,
2725                          SystemDictionary::MethodHandleNatives_klass(),
2726                          vmSymbols::findMethodHandleType_name(),
2727                          vmSymbols::findMethodHandleType_signature(),
2728                          &args, CHECK_(empty));
2729   Handle method_type(THREAD, (oop) result.get_jobject());
2730 
2731   if (can_be_cached) {
2732     // We can cache this MethodType inside the JVM.
2733     MutexLocker ml(SystemDictionary_lock, THREAD);
2734     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2735     if (spe == NULL)
2736       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2737     if (spe->method_type() == NULL) {
2738       spe->set_method_type(method_type());
2739     }
2740   }
2741 
2742   // report back to the caller with the MethodType
2743   return method_type;
2744 }
2745 
2746 // Ask Java code to find or construct a method handle constant.
2747 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2748                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2749                                                      Klass* callee,
2750                                                      Symbol* name_sym,
2751                                                      Symbol* signature,
2752                                                      TRAPS) {
2753   Handle empty;
2754   Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2755   Handle type;
2756   if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2757     type = find_method_handle_type(signature, caller, CHECK_(empty));
2758   } else if (caller == NULL) {
2759     // This should not happen.  JDK code should take care of that.
2760     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2761   } else {
2762     ResourceMark rm(THREAD);
2763     SignatureStream ss(signature, false);
2764     if (!ss.is_done()) {
2765       oop mirror = ss.as_java_mirror(Handle(THREAD, caller->class_loader()),
2766                                      Handle(THREAD, caller->protection_domain()),
2767                                      SignatureStream::NCDFError, CHECK_(empty));
2768       type = Handle(THREAD, mirror);
2769       ss.next();
2770       if (!ss.is_done())  type = Handle();  // error!
2771     }
2772   }
2773   if (type.is_null()) {
2774     THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2775   }
2776 
2777   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2778   JavaCallArguments args;
2779   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2780   args.push_int(ref_kind);
2781   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2782   args.push_oop(name);
2783   args.push_oop(type);
2784   JavaValue result(T_OBJECT);
2785   JavaCalls::call_static(&result,
2786                          SystemDictionary::MethodHandleNatives_klass(),
2787                          vmSymbols::linkMethodHandleConstant_name(),
2788                          vmSymbols::linkMethodHandleConstant_signature(),
2789                          &args, CHECK_(empty));
2790   return Handle(THREAD, (oop) result.get_jobject());
2791 }
2792 
2793 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2794 // name and signature, as interpreted relative to the given class loader.
2795 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller,
2796                                                               Handle bootstrap_specifier,
2797                                                               Symbol* name,
2798                                                               Symbol* type,
2799                                                               Handle *appendix_result,
2800                                                               Handle *method_type_result,
2801                                                               TRAPS) {
2802   methodHandle empty;
2803   Handle bsm, info;
2804   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2805     bsm = bootstrap_specifier;
2806   } else {
2807     assert(bootstrap_specifier->is_objArray(), "");
2808     objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2809     int len = args->length();
2810     assert(len >= 1, "");
2811     bsm = Handle(THREAD, args->obj_at(0));
2812     if (len > 1) {
2813       objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2814       for (int i = 1; i < len; i++)
2815         args1->obj_at_put(i-1, args->obj_at(i));
2816       info = Handle(THREAD, args1);
2817     }
2818   }
2819   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2820             "caller must supply a valid BSM");
2821 
2822   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2823   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2824 
2825   // This should not happen.  JDK code should take care of that.
2826   if (caller == NULL || method_type.is_null()) {
2827     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2828   }
2829 
2830   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2831   assert(appendix_box->obj_at(0) == NULL, "");
2832 
2833   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2834   JavaCallArguments args;
2835   args.push_oop(Handle(THREAD, caller->java_mirror()));
2836   args.push_oop(bsm);
2837   args.push_oop(method_name);
2838   args.push_oop(method_type);
2839   args.push_oop(info);
2840   args.push_oop(appendix_box);
2841   JavaValue result(T_OBJECT);
2842   JavaCalls::call_static(&result,
2843                          SystemDictionary::MethodHandleNatives_klass(),
2844                          vmSymbols::linkCallSite_name(),
2845                          vmSymbols::linkCallSite_signature(),
2846                          &args, CHECK_(empty));
2847   Handle mname(THREAD, (oop) result.get_jobject());
2848   (*method_type_result) = method_type;
2849   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2850 }
2851 
2852 // Protection domain cache table handling
2853 
2854 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2855   return _pd_cache_table->get(protection_domain);
2856 }
2857 
2858 void SystemDictionary::reorder_dictionary_for_sharing() {
2859   ClassLoaderData::the_null_class_loader_data()->dictionary()->reorder_dictionary_for_sharing();
2860 }
2861 
2862 size_t SystemDictionary::count_bytes_for_buckets() {
2863   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_buckets();
2864 }
2865 
2866 size_t SystemDictionary::count_bytes_for_table() {
2867   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_table();
2868 }
2869 
2870 void SystemDictionary::copy_buckets(char* top, char* end) {
2871   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_buckets(top, end);
2872 }
2873 
2874 void SystemDictionary::copy_table(char* top, char* end) {
2875   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_table(top, end);
2876 }
2877 
2878 // ----------------------------------------------------------------------------
2879 void SystemDictionary::print_shared(outputStream *st) {
2880   shared_dictionary()->print_on(st);
2881 }
2882 
2883 void SystemDictionary::print_on(outputStream *st) {
2884   if (shared_dictionary() != NULL) {
2885     st->print_cr("Shared Dictionary");
2886     shared_dictionary()->print_on(st);
2887     st->cr();
2888   }
2889 
2890   GCMutexLocker mu(SystemDictionary_lock);
2891 
2892   ClassLoaderDataGraph::print_dictionary(st);
2893 
2894   // Placeholders
2895   placeholders()->print_on(st);
2896   st->cr();
2897 
2898   // loader constraints - print under SD_lock
2899   constraints()->print_on(st);
2900   st->cr();
2901 
2902   _pd_cache_table->print_on(st);
2903   st->cr();
2904 }
2905 
2906 void SystemDictionary::verify() {
2907   guarantee(constraints() != NULL,
2908             "Verify of loader constraints failed");
2909   guarantee(placeholders()->number_of_entries() >= 0,
2910             "Verify of placeholders failed");
2911 
2912   GCMutexLocker mu(SystemDictionary_lock);
2913 
2914   // Verify dictionary
2915   ClassLoaderDataGraph::verify_dictionary();
2916 
2917   placeholders()->verify();
2918 
2919   // Verify constraint table
2920   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2921   constraints()->verify(placeholders());
2922 
2923   _pd_cache_table->verify();
2924 }
2925 
2926 void SystemDictionary::dump(outputStream *st, bool verbose) {
2927   assert_locked_or_safepoint(SystemDictionary_lock);
2928   if (verbose) {
2929     print_on(st);
2930   } else {
2931     if (shared_dictionary() != NULL) {
2932       shared_dictionary()->print_table_statistics(st, "Shared Dictionary");
2933     }
2934     ClassLoaderDataGraph::print_dictionary_statistics(st);
2935     placeholders()->print_table_statistics(st, "Placeholder Table");
2936     constraints()->print_table_statistics(st, "LoaderConstraints Table");
2937     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
2938   }
2939 }
2940 
2941 // Utility for dumping dictionaries.
2942 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2943                                  DCmdWithParser(output, heap),
2944   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2945            "BOOLEAN", false, "false") {
2946   _dcmdparser.add_dcmd_option(&_verbose);
2947 }
2948 
2949 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2950   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2951                          _verbose.value());
2952   VMThread::execute(&dumper);
2953 }
2954 
2955 int SystemDictionaryDCmd::num_arguments() {
2956   ResourceMark rm;
2957   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
2958   if (dcmd != NULL) {
2959     DCmdMark mark(dcmd);
2960     return dcmd->_dcmdparser.num_arguments();
2961   } else {
2962     return 0;
2963   }
2964 }
2965 
2966 class CombineDictionariesClosure : public CLDClosure {
2967   private:
2968     Dictionary* _master_dictionary;
2969   public:
2970     CombineDictionariesClosure(Dictionary* master_dictionary) :
2971       _master_dictionary(master_dictionary) {}
2972     void do_cld(ClassLoaderData* cld) {
2973       ResourceMark rm;
2974       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
2975         for (int i = 0; i < cld->dictionary()->table_size(); ++i) {
2976           Dictionary* curr_dictionary = cld->dictionary();
2977           DictionaryEntry* p = curr_dictionary->bucket(i);
2978           while (p != NULL) {
2979             Symbol* name = p->instance_klass()->name();
2980             unsigned int d_hash = _master_dictionary->compute_hash(name);
2981             int d_index = _master_dictionary->hash_to_index(d_hash);
2982             DictionaryEntry* next = p->next();
2983             if (p->literal()->class_loader_data() != cld) {
2984               // This is an initiating class loader entry; don't use it
2985               log_trace(cds)("Skipping initiating cl entry: %s", name->as_C_string());
2986               curr_dictionary->free_entry(p);
2987             } else {
2988               log_trace(cds)("Moved to boot dictionary: %s", name->as_C_string());
2989               curr_dictionary->unlink_entry(p);
2990               p->set_pd_set(NULL); // pd_set is runtime only information and will be reconstructed.
2991               _master_dictionary->add_entry(d_index, p);
2992             }
2993             p = next;
2994           }
2995           *curr_dictionary->bucket_addr(i) = NULL;
2996         }
2997       }
2998     }
2999 };
3000 
3001 // Combining platform and system loader dictionaries into boot loader dictionaries.
3002 // During run time, we only have one shared dictionary.
3003 void SystemDictionary::combine_shared_dictionaries() {
3004   assert(DumpSharedSpaces, "dump time only");
3005   Dictionary* master_dictionary = ClassLoaderData::the_null_class_loader_data()->dictionary();
3006   CombineDictionariesClosure cdc(master_dictionary);
3007   ClassLoaderDataGraph::cld_do(&cdc);
3008 
3009   // These tables are no longer valid or necessary. Keeping them around will
3010   // cause SystemDictionary::verify() to fail. Let's empty them.
3011   _placeholders        = new PlaceholderTable(_placeholder_table_size);
3012   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
3013 
3014   NOT_PRODUCT(SystemDictionary::verify());
3015 }
3016 
3017 // caller needs ResourceMark
3018 const char* SystemDictionary::loader_name(const oop loader) {
3019   return ((loader) == NULL ? "<bootloader>" :
3020           InstanceKlass::cast((loader)->klass())->name()->as_C_string());
3021 }
3022 
3023 // caller needs ResourceMark
3024 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) {
3025   return (loader_data->class_loader() == NULL ? "<bootloader>" :
3026           SystemDictionary::loader_name(loader_data->class_loader()));
3027 }
--- EOF ---