1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "aot/aotLoader.hpp"
  28 #include "classfile/classFileParser.hpp"
  29 #include "classfile/classFileStream.hpp"
  30 #include "classfile/classLoader.hpp"
  31 #include "classfile/classLoaderData.inline.hpp"
  32 #include "classfile/classLoaderExt.hpp"
  33 #include "classfile/dictionary.hpp"
  34 #include "classfile/javaClasses.inline.hpp"
  35 #include "classfile/klassFactory.hpp"
  36 #include "classfile/loaderConstraints.hpp"
  37 #include "classfile/packageEntry.hpp"
  38 #include "classfile/placeholders.hpp"
  39 #include "classfile/protectionDomainCache.hpp"
  40 #include "classfile/resolutionErrors.hpp"
  41 #include "classfile/stringTable.hpp"
  42 #include "classfile/systemDictionary.hpp"
  43 #include "classfile/vmSymbols.hpp"
  44 #include "code/codeCache.hpp"
  45 #include "compiler/compileBroker.hpp"
  46 #include "gc/shared/gcTraceTime.inline.hpp"
  47 #include "gc/shared/oopStorage.inline.hpp"
  48 #include "interpreter/bytecodeStream.hpp"
  49 #include "interpreter/interpreter.hpp"
  50 #include "jfr/jfrEvents.hpp"
  51 #include "logging/log.hpp"
  52 #include "logging/logStream.hpp"
  53 #include "memory/filemap.hpp"
  54 #include "memory/metaspaceClosure.hpp"
  55 #include "memory/oopFactory.hpp"
  56 #include "memory/resourceArea.hpp"
  57 #include "oops/access.inline.hpp"
  58 #include "oops/instanceKlass.hpp"
  59 #include "oops/instanceRefKlass.hpp"
  60 #include "oops/klass.inline.hpp"
  61 #include "oops/method.inline.hpp"
  62 #include "oops/methodData.hpp"
  63 #include "oops/objArrayKlass.hpp"
  64 #include "oops/objArrayOop.inline.hpp"
  65 #include "oops/oop.inline.hpp"
  66 #include "oops/symbol.hpp"
  67 #include "oops/typeArrayKlass.hpp"
  68 #include "prims/jvmtiEnvBase.hpp"
  69 #include "prims/resolvedMethodTable.hpp"
  70 #include "prims/methodHandles.hpp"
  71 #include "runtime/arguments.hpp"
  72 #include "runtime/arguments_ext.hpp"
  73 #include "runtime/biasedLocking.hpp"
  74 #include "runtime/fieldType.hpp"
  75 #include "runtime/handles.inline.hpp"
  76 #include "runtime/java.hpp"
  77 #include "runtime/javaCalls.hpp"
  78 #include "runtime/mutexLocker.hpp"
  79 #include "runtime/orderAccess.hpp"
  80 #include "runtime/sharedRuntime.hpp"
  81 #include "runtime/signature.hpp"
  82 #include "services/classLoadingService.hpp"
  83 #include "services/diagnosticCommand.hpp"
  84 #include "services/threadService.hpp"
  85 #include "utilities/macros.hpp"
  86 #if INCLUDE_CDS
  87 #include "classfile/systemDictionaryShared.hpp"
  88 #endif
  89 #if INCLUDE_JVMCI
  90 #include "jvmci/jvmciRuntime.hpp"
  91 #endif
  92 
  93 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  94 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;
  95 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  96 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  97 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
  98 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
  99 
 100 int         SystemDictionary::_number_of_modifications = 0;
 101 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 102 
 103 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 104                                                           =  { NULL /*, NULL...*/ };
 105 
 106 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 107 
 108 oop         SystemDictionary::_java_system_loader         =  NULL;
 109 oop         SystemDictionary::_java_platform_loader       =  NULL;
 110 
 111 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 112 
 113 // Default ProtectionDomainCacheSize value
 114 
 115 const int defaultProtectionDomainCacheSize = 1009;
 116 
 117 OopStorage* SystemDictionary::_vm_weak_oop_storage = NULL;
 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 
 151 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
 152   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 153   return ClassLoaderDataGraph::find_or_create(class_loader);
 154 }
 155 
 156 // ----------------------------------------------------------------------------
 157 // Parallel class loading check
 158 
 159 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 160   if (class_loader.is_null()) return true;
 161   if (AlwaysLockClassLoader) return false;
 162   return java_lang_ClassLoader::parallelCapable(class_loader());
 163 }
 164 // ----------------------------------------------------------------------------
 165 // ParallelDefineClass flag does not apply to bootclass loader
 166 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 167    if (class_loader.is_null()) return false;
 168    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 169      return true;
 170    }
 171    return false;
 172 }
 173 
 174 // Returns true if the passed class loader is the builtin application class loader
 175 // or a custom system class loader. A customer system class loader can be
 176 // specified via -Djava.system.class.loader.
 177 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 178   if (class_loader == NULL) {
 179     return false;
 180   }
 181   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 182          oopDesc::equals(class_loader, _java_system_loader));
 183 }
 184 
 185 // Returns true if the passed class loader is the platform class loader.
 186 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 187   if (class_loader == NULL) {
 188     return false;
 189   }
 190   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 191 }
 192 
 193 // ----------------------------------------------------------------------------
 194 // Resolving of classes
 195 
 196 // Forwards to resolve_or_null
 197 
 198 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 199   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 200   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 201     // can return a null klass
 202     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 203   }
 204   return klass;
 205 }
 206 
 207 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 208                                                      bool throw_error,
 209                                                      Klass* klass, TRAPS) {
 210   if (HAS_PENDING_EXCEPTION) {
 211     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 212     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 213     // and if so convert it to a NoClassDefFoundError
 214     // And chain the original ClassNotFoundException
 215     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 216       ResourceMark rm(THREAD);
 217       assert(klass == NULL, "Should not have result with exception pending");
 218       Handle e(THREAD, PENDING_EXCEPTION);
 219       CLEAR_PENDING_EXCEPTION;
 220       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 221     } else {
 222       return NULL;
 223     }
 224   }
 225   // Class not found, throw appropriate error or exception depending on value of throw_error
 226   if (klass == NULL) {
 227     ResourceMark rm(THREAD);
 228     if (throw_error) {
 229       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 230     } else {
 231       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 232     }
 233   }
 234   return klass;
 235 }
 236 
 237 
 238 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 239                                            bool throw_error, TRAPS)
 240 {
 241   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 242 }
 243 
 244 
 245 // Forwards to resolve_instance_class_or_null
 246 
 247 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 248   if (FieldType::is_array(class_name)) {
 249     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 250   } else if (FieldType::is_obj(class_name)) {
 251     ResourceMark rm(THREAD);
 252     // Ignore wrapping L and ;.
 253     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 254                                    class_name->utf8_length() - 2, CHECK_NULL);
 255     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 256   } else {
 257     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 258   }
 259 }
 260 
 261 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 262   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 263 }
 264 
 265 // Forwards to resolve_instance_class_or_null
 266 
 267 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 268                                                      Handle class_loader,
 269                                                      Handle protection_domain,
 270                                                      TRAPS) {
 271   assert(FieldType::is_array(class_name), "must be array");
 272   Klass* k = NULL;
 273   FieldArrayInfo fd;
 274   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 275   // of this call
 276   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 277   if (t == T_OBJECT) {
 278     // naked oop "k" is OK here -- we assign back into it
 279     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 280                                                          class_loader,
 281                                                          protection_domain,
 282                                                          CHECK_NULL);
 283     if (k != NULL) {
 284       k = k->array_klass(fd.dimension(), CHECK_NULL);
 285     }
 286   } else {
 287     k = Universe::typeArrayKlassObj(t);
 288     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 289   }
 290   return k;
 291 }
 292 
 293 
 294 // Must be called for any super-class or super-interface resolution
 295 // during class definition to allow class circularity checking
 296 // super-interface callers:
 297 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 298 // super-class callers:
 299 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 300 //   load_shared_class - while loading a class from shared archive
 301 //   resolve_instance_class_or_null:
 302 //     via: handle_parallel_super_load
 303 //      when resolving a class that has an existing placeholder with
 304 //      a saved superclass [i.e. a defineClass is currently in progress]
 305 //      if another thread is trying to resolve the class, it must do
 306 //      super-class checks on its own thread to catch class circularity
 307 // This last call is critical in class circularity checking for cases
 308 // where classloading is delegated to different threads and the
 309 // classloader lock is released.
 310 // Take the case: Base->Super->Base
 311 //   1. If thread T1 tries to do a defineClass of class Base
 312 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 313 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 314 //    so it tries to load Super
 315 //   3. If we load the class internally, or user classloader uses same thread
 316 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 317 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 318 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 319 //      3.4 calls resolve_super_or_fail Base
 320 //      3.5 finds T1,Base -> throws class circularity
 321 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 322 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 323 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 324 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 325 //      4.4 finds T2, Super -> throws class circularity
 326 // Must be called, even if superclass is null, since this is
 327 // where the placeholder entry is created which claims this
 328 // thread is loading this class/classloader.
 329 // Be careful when modifying this code: once you have run
 330 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 331 // you need to find_and_remove it before returning.
 332 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 333 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 334                                                  Symbol* class_name,
 335                                                  Handle class_loader,
 336                                                  Handle protection_domain,
 337                                                  bool is_superclass,
 338                                                  TRAPS) {
 339 #if INCLUDE_CDS
 340   if (DumpSharedSpaces) {
 341     // Special processing for CDS dump time.
 342     Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 343         class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 344     if (k) {
 345       return k;
 346     }
 347   }
 348 #endif // INCLUDE_CDS
 349 
 350   // Double-check, if child class is already loaded, just return super-class,interface
 351   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 352   // dictionary.
 353   // Make sure there's a placeholder for the *child* before resolving.
 354   // Used as a claim that this thread is currently loading superclass/classloader
 355   // Used here for ClassCircularity checks and also for heap verification
 356   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 357   // Must check ClassCircularity before checking if super class is already loaded.
 358   //
 359   // We might not already have a placeholder if this child_name was
 360   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 361   // the name of the class might not be known until the stream is actually
 362   // parsed.
 363   // Bugs 4643874, 4715493
 364 
 365   ClassLoaderData* loader_data = class_loader_data(class_loader);
 366   Dictionary* dictionary = loader_data->dictionary();
 367   unsigned int d_hash = dictionary->compute_hash(child_name);
 368   unsigned int p_hash = placeholders()->compute_hash(child_name);
 369   int p_index = placeholders()->hash_to_index(p_hash);
 370   // can't throw error holding a lock
 371   bool child_already_loaded = false;
 372   bool throw_circularity_error = false;
 373   {
 374     MutexLocker mu(SystemDictionary_lock, THREAD);
 375     Klass* childk = find_class(d_hash, child_name, dictionary);
 376     Klass* quicksuperk;
 377     // to support // loading: if child done loading, just return superclass
 378     // if class_name, & class_loader don't match:
 379     // if initial define, SD update will give LinkageError
 380     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 381     // so we don't throw an exception here.
 382     // see: nsk redefclass014 & java.lang.instrument Instrument032
 383     if ((childk != NULL ) && (is_superclass) &&
 384        ((quicksuperk = childk->super()) != NULL) &&
 385 
 386          ((quicksuperk->name() == class_name) &&
 387             (oopDesc::equals(quicksuperk->class_loader(), class_loader())))) {
 388            return quicksuperk;
 389     } else {
 390       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 391       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 392           throw_circularity_error = true;
 393       }
 394     }
 395     if (!throw_circularity_error) {
 396       // Be careful not to exit resolve_super
 397       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 398     }
 399   }
 400   if (throw_circularity_error) {
 401       ResourceMark rm(THREAD);
 402       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 403   }
 404 
 405 // java.lang.Object should have been found above
 406   assert(class_name != NULL, "null super class for resolving");
 407   // Resolve the super class or interface, check results on return
 408   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 409                                                     class_loader,
 410                                                     protection_domain,
 411                                                     THREAD);
 412 
 413   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 414   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 415   // or error. GC used to walk the placeholder table as strong roots.
 416   // The instanceKlass is kept alive because the class loader is on the stack,
 417   // which keeps the loader_data alive, as well as all instanceKlasses in
 418   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 419   {
 420     MutexLocker mu(SystemDictionary_lock, THREAD);
 421     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 422     SystemDictionary_lock->notify_all();
 423   }
 424   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 425     // can null superk
 426     superk = handle_resolution_exception(class_name, true, superk, THREAD);
 427   }
 428 
 429   return superk;
 430 }
 431 
 432 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 433                                                   Handle class_loader,
 434                                                   Handle protection_domain,
 435                                                   TRAPS) {
 436   if(!has_checkPackageAccess()) return;
 437 
 438   // Now we have to call back to java to check if the initating class has access
 439   JavaValue result(T_VOID);
 440   LogTarget(Debug, protectiondomain) lt;
 441   if (lt.is_enabled()) {
 442     ResourceMark rm;
 443     // Print out trace information
 444     LogStream ls(lt);
 445     ls.print_cr("Checking package access");
 446     ls.print("class loader: "); class_loader()->print_value_on(&ls);
 447     ls.print(" protection domain: "); protection_domain()->print_value_on(&ls);
 448     ls.print(" loading: "); klass->print_value_on(&ls);
 449     ls.cr();
 450   }
 451 
 452   // This handle and the class_loader handle passed in keeps this class from
 453   // being unloaded through several GC points.
 454   // The class_loader handle passed in is the initiating loader.
 455   Handle mirror(THREAD, klass->java_mirror());
 456 
 457   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 458   JavaCalls::call_special(&result,
 459                          class_loader,
 460                          system_loader,
 461                          vmSymbols::checkPackageAccess_name(),
 462                          vmSymbols::class_protectiondomain_signature(),
 463                          mirror,
 464                          protection_domain,
 465                          THREAD);
 466 
 467   if (HAS_PENDING_EXCEPTION) {
 468     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 469   } else {
 470    log_debug(protectiondomain)("granted");
 471   }
 472 
 473   if (HAS_PENDING_EXCEPTION) return;
 474 
 475   // If no exception has been thrown, we have validated the protection domain
 476   // Insert the protection domain of the initiating class into the set.
 477   {
 478     ClassLoaderData* loader_data = class_loader_data(class_loader);
 479     Dictionary* dictionary = loader_data->dictionary();
 480 
 481     Symbol*  kn = klass->name();
 482     unsigned int d_hash = dictionary->compute_hash(kn);
 483 
 484     MutexLocker mu(SystemDictionary_lock, THREAD);
 485     int d_index = dictionary->hash_to_index(d_hash);
 486     dictionary->add_protection_domain(d_index, d_hash, klass,
 487                                       protection_domain, THREAD);
 488   }
 489 }
 490 
 491 // We only get here if this thread finds that another thread
 492 // has already claimed the placeholder token for the current operation,
 493 // but that other thread either never owned or gave up the
 494 // object lock
 495 // Waits on SystemDictionary_lock to indicate placeholder table updated
 496 // On return, caller must recheck placeholder table state
 497 //
 498 // We only get here if
 499 //  1) custom classLoader, i.e. not bootstrap classloader
 500 //  2) custom classLoader has broken the class loader objectLock
 501 //     so another thread got here in parallel
 502 //
 503 // lockObject must be held.
 504 // Complicated dance due to lock ordering:
 505 // Must first release the classloader object lock to
 506 // allow initial definer to complete the class definition
 507 // and to avoid deadlock
 508 // Reclaim classloader lock object with same original recursion count
 509 // Must release SystemDictionary_lock after notify, since
 510 // class loader lock must be claimed before SystemDictionary_lock
 511 // to prevent deadlocks
 512 //
 513 // The notify allows applications that did an untimed wait() on
 514 // the classloader object lock to not hang.
 515 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 516   assert_lock_strong(SystemDictionary_lock);
 517 
 518   bool calledholdinglock
 519       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 520   assert(calledholdinglock,"must hold lock for notify");
 521   assert((!oopDesc::equals(lockObject(), _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 522   ObjectSynchronizer::notifyall(lockObject, THREAD);
 523   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 524   SystemDictionary_lock->wait();
 525   SystemDictionary_lock->unlock();
 526   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 527   SystemDictionary_lock->lock();
 528 }
 529 
 530 // If the class in is in the placeholder table, class loading is in progress
 531 // For cases where the application changes threads to load classes, it
 532 // is critical to ClassCircularity detection that we try loading
 533 // the superclass on the same thread internally, so we do parallel
 534 // super class loading here.
 535 // This also is critical in cases where the original thread gets stalled
 536 // even in non-circularity situations.
 537 // Note: must call resolve_super_or_fail even if null super -
 538 // to force placeholder entry creation for this class for circularity detection
 539 // Caller must check for pending exception
 540 // Returns non-null Klass* if other thread has completed load
 541 // and we are done,
 542 // If return null Klass* and no pending exception, the caller must load the class
 543 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 544     Symbol* name, Symbol* superclassname, Handle class_loader,
 545     Handle protection_domain, Handle lockObject, TRAPS) {
 546 
 547   ClassLoaderData* loader_data = class_loader_data(class_loader);
 548   Dictionary* dictionary = loader_data->dictionary();
 549   unsigned int d_hash = dictionary->compute_hash(name);
 550   unsigned int p_hash = placeholders()->compute_hash(name);
 551   int p_index = placeholders()->hash_to_index(p_hash);
 552 
 553   // superk is not used, resolve_super called for circularity check only
 554   // This code is reached in two situations. One if this thread
 555   // is loading the same class twice (e.g. ClassCircularity, or
 556   // java.lang.instrument).
 557   // The second is if another thread started the resolve_super first
 558   // and has not yet finished.
 559   // In both cases the original caller will clean up the placeholder
 560   // entry on error.
 561   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 562                                                           superclassname,
 563                                                           class_loader,
 564                                                           protection_domain,
 565                                                           true,
 566                                                           CHECK_NULL);
 567 
 568   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 569   // Serial class loaders and bootstrap classloader do wait for superclass loads
 570  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 571     MutexLocker mu(SystemDictionary_lock, THREAD);
 572     // Check if classloading completed while we were loading superclass or waiting
 573     return find_class(d_hash, name, dictionary);
 574   }
 575 
 576   // must loop to both handle other placeholder updates
 577   // and spurious notifications
 578   bool super_load_in_progress = true;
 579   PlaceholderEntry* placeholder;
 580   while (super_load_in_progress) {
 581     MutexLocker mu(SystemDictionary_lock, THREAD);
 582     // Check if classloading completed while we were loading superclass or waiting
 583     InstanceKlass* check = find_class(d_hash, name, dictionary);
 584     if (check != NULL) {
 585       // Klass is already loaded, so just return it
 586       return check;
 587     } else {
 588       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 589       if (placeholder && placeholder->super_load_in_progress() ){
 590         // We only get here if the application has released the
 591         // classloader lock when another thread was in the middle of loading a
 592         // superclass/superinterface for this class, and now
 593         // this thread is also trying to load this class.
 594         // To minimize surprises, the first thread that started to
 595         // load a class should be the one to complete the loading
 596         // with the classfile it initially expected.
 597         // This logic has the current thread wait once it has done
 598         // all the superclass/superinterface loading it can, until
 599         // the original thread completes the class loading or fails
 600         // If it completes we will use the resulting InstanceKlass
 601         // which we will find below in the systemDictionary.
 602         // We also get here for parallel bootstrap classloader
 603         if (class_loader.is_null()) {
 604           SystemDictionary_lock->wait();
 605         } else {
 606           double_lock_wait(lockObject, THREAD);
 607         }
 608       } else {
 609         // If not in SD and not in PH, other thread's load must have failed
 610         super_load_in_progress = false;
 611       }
 612     }
 613   }
 614   return NULL;
 615 }
 616 
 617 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
 618   assert(event != NULL, "invariant");
 619   assert(k != NULL, "invariant");
 620   assert(event->should_commit(), "invariant");
 621   event->set_loadedClass(k);
 622   event->set_definingClassLoader(k->class_loader_data());
 623   event->set_initiatingClassLoader(init_cld);
 624   event->commit();
 625 }
 626 
 627 
 628 // Be careful when modifying this code: once you have run
 629 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 630 // you need to find_and_remove it before returning.
 631 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 632 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 633                                                         Handle class_loader,
 634                                                         Handle protection_domain,
 635                                                         TRAPS) {
 636   assert(name != NULL && !FieldType::is_array(name) &&
 637          !FieldType::is_obj(name), "invalid class name");
 638 
 639   EventClassLoad class_load_start_event;
 640 
 641   HandleMark hm(THREAD);
 642 
 643   // Fix for 4474172; see evaluation for more details
 644   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 645   ClassLoaderData* loader_data = register_loader(class_loader);
 646   Dictionary* dictionary = loader_data->dictionary();
 647   unsigned int d_hash = dictionary->compute_hash(name);
 648 
 649   // Do lookup to see if class already exist and the protection domain
 650   // has the right access
 651   // This call uses find which checks protection domain already matches
 652   // All subsequent calls use find_class, and set has_loaded_class so that
 653   // before we return a result we call out to java to check for valid protection domain
 654   // to allow returning the Klass* and add it to the pd_set if it is valid
 655   {
 656     Klass* probe = dictionary->find(d_hash, name, protection_domain);
 657     if (probe != NULL) return probe;
 658   }
 659 
 660   // Non-bootstrap class loaders will call out to class loader and
 661   // define via jvm/jni_DefineClass which will acquire the
 662   // class loader object lock to protect against multiple threads
 663   // defining the class in parallel by accident.
 664   // This lock must be acquired here so the waiter will find
 665   // any successful result in the SystemDictionary and not attempt
 666   // the define.
 667   // ParallelCapable Classloaders and the bootstrap classloader
 668   // do not acquire lock here.
 669   bool DoObjectLock = true;
 670   if (is_parallelCapable(class_loader)) {
 671     DoObjectLock = false;
 672   }
 673 
 674   unsigned int p_hash = placeholders()->compute_hash(name);
 675   int p_index = placeholders()->hash_to_index(p_hash);
 676 
 677   // Class is not in SystemDictionary so we have to do loading.
 678   // Make sure we are synchronized on the class loader before we proceed
 679   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 680   check_loader_lock_contention(lockObject, THREAD);
 681   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 682 
 683   // Check again (after locking) if class already exist in SystemDictionary
 684   bool class_has_been_loaded   = false;
 685   bool super_load_in_progress  = false;
 686   bool havesupername = false;
 687   InstanceKlass* k = NULL;
 688   PlaceholderEntry* placeholder;
 689   Symbol* superclassname = NULL;
 690 
 691   assert(THREAD->can_call_java(),
 692          "can not load classes with compiler thread: class=%s, classloader=%s",
 693          name->as_C_string(),
 694          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 695   {
 696     MutexLocker mu(SystemDictionary_lock, THREAD);
 697     InstanceKlass* check = find_class(d_hash, name, dictionary);
 698     if (check != NULL) {
 699       // Klass is already loaded, so just return it
 700       class_has_been_loaded = true;
 701       k = check;
 702     } else {
 703       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 704       if (placeholder && placeholder->super_load_in_progress()) {
 705          super_load_in_progress = true;
 706          if (placeholder->havesupername() == true) {
 707            superclassname = placeholder->supername();
 708            havesupername = true;
 709          }
 710       }
 711     }
 712   }
 713 
 714   // If the class is in the placeholder table, class loading is in progress
 715   if (super_load_in_progress && havesupername==true) {
 716     k = handle_parallel_super_load(name,
 717                                    superclassname,
 718                                    class_loader,
 719                                    protection_domain,
 720                                    lockObject, THREAD);
 721     if (HAS_PENDING_EXCEPTION) {
 722       return NULL;
 723     }
 724     if (k != NULL) {
 725       class_has_been_loaded = true;
 726     }
 727   }
 728 
 729   bool throw_circularity_error = false;
 730   if (!class_has_been_loaded) {
 731     bool load_instance_added = false;
 732 
 733     // add placeholder entry to record loading instance class
 734     // Five cases:
 735     // All cases need to prevent modifying bootclasssearchpath
 736     // in parallel with a classload of same classname
 737     // Redefineclasses uses existence of the placeholder for the duration
 738     // of the class load to prevent concurrent redefinition of not completely
 739     // defined classes.
 740     // case 1. traditional classloaders that rely on the classloader object lock
 741     //   - no other need for LOAD_INSTANCE
 742     // case 2. traditional classloaders that break the classloader object lock
 743     //    as a deadlock workaround. Detection of this case requires that
 744     //    this check is done while holding the classloader object lock,
 745     //    and that lock is still held when calling classloader's loadClass.
 746     //    For these classloaders, we ensure that the first requestor
 747     //    completes the load and other requestors wait for completion.
 748     // case 3. Bootstrap classloader - don't own objectLocker
 749     //    This classloader supports parallelism at the classloader level,
 750     //    but only allows a single load of a class/classloader pair.
 751     //    No performance benefit and no deadlock issues.
 752     // case 4. parallelCapable user level classloaders - without objectLocker
 753     //    Allow parallel classloading of a class/classloader pair
 754 
 755     {
 756       MutexLocker mu(SystemDictionary_lock, THREAD);
 757       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 758         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 759         if (oldprobe) {
 760           // only need check_seen_thread once, not on each loop
 761           // 6341374 java/lang/Instrument with -Xcomp
 762           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 763             throw_circularity_error = true;
 764           } else {
 765             // case 1: traditional: should never see load_in_progress.
 766             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 767 
 768               // case 3: bootstrap classloader: prevent futile classloading,
 769               // wait on first requestor
 770               if (class_loader.is_null()) {
 771                 SystemDictionary_lock->wait();
 772               } else {
 773               // case 2: traditional with broken classloader lock. wait on first
 774               // requestor.
 775                 double_lock_wait(lockObject, THREAD);
 776               }
 777               // Check if classloading completed while we were waiting
 778               InstanceKlass* check = find_class(d_hash, name, dictionary);
 779               if (check != NULL) {
 780                 // Klass is already loaded, so just return it
 781                 k = check;
 782                 class_has_been_loaded = true;
 783               }
 784               // check if other thread failed to load and cleaned up
 785               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 786             }
 787           }
 788         }
 789       }
 790       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 791       // case 4: parallelCapable: allow competing threads to try
 792       // LOAD_INSTANCE in parallel
 793 
 794       if (!throw_circularity_error && !class_has_been_loaded) {
 795         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 796         load_instance_added = true;
 797         // For class loaders that do not acquire the classloader object lock,
 798         // if they did not catch another thread holding LOAD_INSTANCE,
 799         // need a check analogous to the acquire ObjectLocker/find_class
 800         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 801         // one final check if the load has already completed
 802         // class loaders holding the ObjectLock shouldn't find the class here
 803         InstanceKlass* check = find_class(d_hash, name, dictionary);
 804         if (check != NULL) {
 805         // Klass is already loaded, so return it after checking/adding protection domain
 806           k = check;
 807           class_has_been_loaded = true;
 808         }
 809       }
 810     }
 811 
 812     // must throw error outside of owning lock
 813     if (throw_circularity_error) {
 814       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 815       ResourceMark rm(THREAD);
 816       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 817     }
 818 
 819     if (!class_has_been_loaded) {
 820 
 821       // Do actual loading
 822       k = load_instance_class(name, class_loader, THREAD);
 823 
 824       // If everything was OK (no exceptions, no null return value), and
 825       // class_loader is NOT the defining loader, do a little more bookkeeping.
 826       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 827         !oopDesc::equals(k->class_loader(), class_loader())) {
 828 
 829         check_constraints(d_hash, k, class_loader, false, THREAD);
 830 
 831         // Need to check for a PENDING_EXCEPTION again; check_constraints
 832         // can throw and doesn't use the CHECK macro.
 833         if (!HAS_PENDING_EXCEPTION) {
 834           { // Grabbing the Compile_lock prevents systemDictionary updates
 835             // during compilations.
 836             MutexLocker mu(Compile_lock, THREAD);
 837             update_dictionary(d_hash, p_index, p_hash,
 838               k, class_loader, THREAD);
 839           }
 840 
 841           if (JvmtiExport::should_post_class_load()) {
 842             Thread *thread = THREAD;
 843             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 844             JvmtiExport::post_class_load((JavaThread *) thread, k);
 845           }
 846         }
 847       }
 848     } // load_instance_class
 849 
 850     if (load_instance_added == true) {
 851       // clean up placeholder entries for LOAD_INSTANCE success or error
 852       // This brackets the SystemDictionary updates for both defining
 853       // and initiating loaders
 854       MutexLocker mu(SystemDictionary_lock, THREAD);
 855       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 856       SystemDictionary_lock->notify_all();
 857     }
 858   }
 859 
 860   if (HAS_PENDING_EXCEPTION || k == NULL) {
 861     return NULL;
 862   }
 863   if (class_load_start_event.should_commit()) {
 864     post_class_load_event(&class_load_start_event, k, loader_data);
 865   }
 866 #ifdef ASSERT
 867   {
 868     ClassLoaderData* loader_data = k->class_loader_data();
 869     MutexLocker mu(SystemDictionary_lock, THREAD);
 870     Klass* kk = find_class(name, loader_data);
 871     assert(kk == k, "should be present in dictionary");
 872   }
 873 #endif
 874 
 875   // return if the protection domain in NULL
 876   if (protection_domain() == NULL) return k;
 877 
 878   // Check the protection domain has the right access
 879   if (dictionary->is_valid_protection_domain(d_hash, name,
 880                                              protection_domain)) {
 881     return k;
 882   }
 883 
 884   // Verify protection domain. If it fails an exception is thrown
 885   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 886 
 887   return k;
 888 }
 889 
 890 
 891 // This routine does not lock the system dictionary.
 892 //
 893 // Since readers don't hold a lock, we must make sure that system
 894 // dictionary entries are only removed at a safepoint (when only one
 895 // thread is running), and are added to in a safe way (all links must
 896 // be updated in an MT-safe manner).
 897 //
 898 // Callers should be aware that an entry could be added just after
 899 // _dictionary->bucket(index) is read here, so the caller will not see
 900 // the new entry.
 901 
 902 Klass* SystemDictionary::find(Symbol* class_name,
 903                               Handle class_loader,
 904                               Handle protection_domain,
 905                               TRAPS) {
 906 
 907   // The result of this call should be consistent with the result
 908   // of the call to resolve_instance_class_or_null().
 909   // See evaluation 6790209 and 4474172 for more details.
 910   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 911   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 912 
 913   if (loader_data == NULL) {
 914     // If the ClassLoaderData has not been setup,
 915     // then the class loader has no entries in the dictionary.
 916     return NULL;
 917   }
 918 
 919   Dictionary* dictionary = loader_data->dictionary();
 920   unsigned int d_hash = dictionary->compute_hash(class_name);
 921   return dictionary->find(d_hash, class_name,
 922                           protection_domain);
 923 }
 924 
 925 
 926 // Look for a loaded instance or array klass by name.  Do not do any loading.
 927 // return NULL in case of error.
 928 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 929                                                       Handle class_loader,
 930                                                       Handle protection_domain,
 931                                                       TRAPS) {
 932   Klass* k = NULL;
 933   assert(class_name != NULL, "class name must be non NULL");
 934 
 935   if (FieldType::is_array(class_name)) {
 936     // The name refers to an array.  Parse the name.
 937     // dimension and object_key in FieldArrayInfo are assigned as a
 938     // side-effect of this call
 939     FieldArrayInfo fd;
 940     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 941     if (t != T_OBJECT) {
 942       k = Universe::typeArrayKlassObj(t);
 943     } else {
 944       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 945     }
 946     if (k != NULL) {
 947       k = k->array_klass_or_null(fd.dimension());
 948     }
 949   } else {
 950     k = find(class_name, class_loader, protection_domain, THREAD);
 951   }
 952   return k;
 953 }
 954 
 955 // Note: this method is much like resolve_from_stream, but
 956 // does not publish the classes via the SystemDictionary.
 957 // Handles unsafe_DefineAnonymousClass and redefineclasses
 958 // RedefinedClasses do not add to the class hierarchy
 959 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
 960                                               Handle class_loader,
 961                                               Handle protection_domain,
 962                                               ClassFileStream* st,
 963                                               const InstanceKlass* host_klass,
 964                                               GrowableArray<Handle>* cp_patches,
 965                                               TRAPS) {
 966 
 967   EventClassLoad class_load_start_event;
 968 
 969   ClassLoaderData* loader_data;
 970   if (host_klass != NULL) {
 971     // Create a new CLD for anonymous class, that uses the same class loader
 972     // as the host_klass
 973     guarantee(oopDesc::equals(host_klass->class_loader(), class_loader()), "should be the same");
 974     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader);
 975   } else {
 976     loader_data = ClassLoaderData::class_loader_data(class_loader());
 977   }
 978 
 979   assert(st != NULL, "invariant");
 980   assert(st->need_verify(), "invariant");
 981 
 982   // Parse stream and create a klass.
 983   // Note that we do this even though this klass might
 984   // already be present in the SystemDictionary, otherwise we would not
 985   // throw potential ClassFormatErrors.
 986 
 987   InstanceKlass* k = KlassFactory::create_from_stream(st,
 988                                                       class_name,
 989                                                       loader_data,
 990                                                       protection_domain,
 991                                                       host_klass,
 992                                                       cp_patches,
 993                                                       CHECK_NULL);
 994 
 995   if (host_klass != NULL && k != NULL) {
 996     // Anonymous classes must update ClassLoaderData holder (was host_klass loader)
 997     // so that they can be unloaded when the mirror is no longer referenced.
 998     k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
 999 
1000     {
1001       MutexLocker mu_r(Compile_lock, THREAD);
1002 
1003       // Add to class hierarchy, initialize vtables, and do possible
1004       // deoptimizations.
1005       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1006 
1007       // But, do not add to dictionary.
1008 
1009       // compiled code dependencies need to be validated anyway
1010       notice_modification();
1011     }
1012 
1013     // Rewrite and patch constant pool here.
1014     k->link_class(CHECK_NULL);
1015     if (cp_patches != NULL) {
1016       k->constants()->patch_resolved_references(cp_patches);
1017     }
1018 
1019     // If it's anonymous, initialize it now, since nobody else will.
1020     k->eager_initialize(CHECK_NULL);
1021 
1022     // notify jvmti
1023     if (JvmtiExport::should_post_class_load()) {
1024         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1025         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1026     }
1027     if (class_load_start_event.should_commit()) {
1028       post_class_load_event(&class_load_start_event, k, loader_data);
1029     }
1030   }
1031   assert(host_klass != NULL || NULL == cp_patches,
1032          "cp_patches only found with host_klass");
1033 
1034   return k;
1035 }
1036 
1037 // Add a klass to the system from a stream (called by jni_DefineClass and
1038 // JVM_DefineClass).
1039 // Note: class_name can be NULL. In that case we do not know the name of
1040 // the class until we have parsed the stream.
1041 
1042 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1043                                                      Handle class_loader,
1044                                                      Handle protection_domain,
1045                                                      ClassFileStream* st,
1046                                                      TRAPS) {
1047 
1048   HandleMark hm(THREAD);
1049 
1050   // Classloaders that support parallelism, e.g. bootstrap classloader,
1051   // do not acquire lock here
1052   bool DoObjectLock = true;
1053   if (is_parallelCapable(class_loader)) {
1054     DoObjectLock = false;
1055   }
1056 
1057   ClassLoaderData* loader_data = register_loader(class_loader);
1058 
1059   // Make sure we are synchronized on the class loader before we proceed
1060   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1061   check_loader_lock_contention(lockObject, THREAD);
1062   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1063 
1064   assert(st != NULL, "invariant");
1065 
1066   // Parse the stream and create a klass.
1067   // Note that we do this even though this klass might
1068   // already be present in the SystemDictionary, otherwise we would not
1069   // throw potential ClassFormatErrors.
1070  InstanceKlass* k = NULL;
1071 
1072 #if INCLUDE_CDS
1073   if (!DumpSharedSpaces) {
1074     k = SystemDictionaryShared::lookup_from_stream(class_name,
1075                                                    class_loader,
1076                                                    protection_domain,
1077                                                    st,
1078                                                    CHECK_NULL);
1079   }
1080 #endif
1081 
1082   if (k == NULL) {
1083     if (st->buffer() == NULL) {
1084       return NULL;
1085     }
1086     k = KlassFactory::create_from_stream(st,
1087                                          class_name,
1088                                          loader_data,
1089                                          protection_domain,
1090                                          NULL, // host_klass
1091                                          NULL, // cp_patches
1092                                          CHECK_NULL);
1093   }
1094 
1095   assert(k != NULL, "no klass created");
1096   Symbol* h_name = k->name();
1097   assert(class_name == NULL || class_name == h_name, "name mismatch");
1098 
1099   // Add class just loaded
1100   // If a class loader supports parallel classloading handle parallel define requests
1101   // find_or_define_instance_class may return a different InstanceKlass
1102   if (is_parallelCapable(class_loader)) {
1103     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1104     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1105       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1106       assert(defined_k != NULL, "Should have a klass if there's no exception");
1107       loader_data->add_to_deallocate_list(k);
1108       k = defined_k;
1109     }
1110   } else {
1111     define_instance_class(k, THREAD);
1112   }
1113 
1114   // If defining the class throws an exception register 'k' for cleanup.
1115   if (HAS_PENDING_EXCEPTION) {
1116     assert(k != NULL, "Must have an instance klass here!");
1117     loader_data->add_to_deallocate_list(k);
1118     return NULL;
1119   }
1120 
1121   // Make sure we have an entry in the SystemDictionary on success
1122   debug_only( {
1123     MutexLocker mu(SystemDictionary_lock, THREAD);
1124 
1125     Klass* check = find_class(h_name, k->class_loader_data());
1126     assert(check == k, "should be present in the dictionary");
1127   } );
1128 
1129   return k;
1130 }
1131 
1132 #if INCLUDE_CDS
1133 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1134                                              int number_of_entries) {
1135   assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>),
1136          "bad shared dictionary size.");
1137   _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(),
1138                                       _shared_dictionary_size, t, number_of_entries);
1139 }
1140 
1141 
1142 // If there is a shared dictionary, then find the entry for the
1143 // given shared system class, if any.
1144 
1145 InstanceKlass* SystemDictionary::find_shared_class(Symbol* class_name) {
1146   if (shared_dictionary() != NULL) {
1147     unsigned int d_hash = shared_dictionary()->compute_hash(class_name);
1148     int d_index = shared_dictionary()->hash_to_index(d_hash);
1149 
1150     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1151   } else {
1152     return NULL;
1153   }
1154 }
1155 
1156 
1157 // Load a class from the shared spaces (found through the shared system
1158 // dictionary).  Force the superclass and all interfaces to be loaded.
1159 // Update the class definition to include sibling classes and no
1160 // subclasses (yet).  [Classes in the shared space are not part of the
1161 // object hierarchy until loaded.]
1162 
1163 InstanceKlass* SystemDictionary::load_shared_class(
1164                  Symbol* class_name, Handle class_loader, TRAPS) {
1165   InstanceKlass* ik = find_shared_class(class_name);
1166   // Make sure we only return the boot class for the NULL classloader.
1167   if (ik != NULL &&
1168       ik->is_shared_boot_class() && class_loader.is_null()) {
1169     Handle protection_domain;
1170     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1171   }
1172   return NULL;
1173 }
1174 
1175 // Check if a shared class can be loaded by the specific classloader:
1176 //
1177 // NULL classloader:
1178 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1179 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1180 //     be defined in an unnamed module.
1181 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1182                                                InstanceKlass* ik,
1183                                                Handle class_loader, TRAPS) {
1184   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1185          "Cannot use sharing if java.base is patched");
1186   ResourceMark rm;
1187   int path_index = ik->shared_classpath_index();
1188   ClassLoaderData* loader_data = class_loader_data(class_loader);
1189   if (path_index < 0) {
1190     // path_index < 0 indicates that the class is intended for a custom loader
1191     // and should not be loaded by boot/platform/app loaders
1192     if (loader_data->is_builtin_class_loader_data()) {
1193       return false;
1194     } else {
1195       return true;
1196     }
1197   }
1198   SharedClassPathEntry* ent =
1199             (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1200   if (!Universe::is_module_initialized()) {
1201     assert(ent != NULL && ent->is_modules_image(),
1202            "Loading non-bootstrap classes before the module system is initialized");
1203     assert(class_loader.is_null(), "sanity");
1204     return true;
1205   }
1206   // Get the pkg_entry from the classloader
1207   TempNewSymbol pkg_name = NULL;
1208   PackageEntry* pkg_entry = NULL;
1209   ModuleEntry* mod_entry = NULL;
1210   const char* pkg_string = NULL;
1211   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1212   if (pkg_name != NULL) {
1213     pkg_string = pkg_name->as_C_string();
1214     if (loader_data != NULL) {
1215       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1216     }
1217     if (pkg_entry != NULL) {
1218       mod_entry = pkg_entry->module();
1219     }
1220   }
1221 
1222   // If the archived class is from a module that has been patched at runtime,
1223   // the class cannot be loaded from the archive.
1224   if (mod_entry != NULL && mod_entry->is_patched()) {
1225     return false;
1226   }
1227 
1228   if (class_loader.is_null()) {
1229     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1230     // The NULL classloader can load archived class originated from the
1231     // "modules" jimage and the -Xbootclasspath/a. For class from the
1232     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1233     // by the NULL classloader.
1234     if (mod_entry != NULL) {
1235       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1236       // ModuleEntry's location agrees with the archived class' origination.
1237       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1238         return true; // Module class from the "module" jimage
1239       }
1240     }
1241 
1242     // If the archived class is not from the "module" jimage, the class can be
1243     // loaded by the NULL classloader if
1244     //
1245     // 1. the class is from the unamed package
1246     // 2. or, the class is not from a module defined in the NULL classloader
1247     // 3. or, the class is from an unamed module
1248     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1249       // the class is from the -Xbootclasspath/a
1250       if (pkg_string == NULL ||
1251           pkg_entry == NULL ||
1252           pkg_entry->in_unnamed_module()) {
1253         assert(mod_entry == NULL ||
1254                mod_entry == loader_data->unnamed_module(),
1255                "the unnamed module is not defined in the classloader");
1256         return true;
1257       }
1258     }
1259     return false;
1260   } else {
1261     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1262               ik, class_loader, pkg_string, pkg_name,
1263               pkg_entry, mod_entry, CHECK_(false));
1264     return res;
1265   }
1266 }
1267 
1268 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1269                                                    Handle class_loader,
1270                                                    Handle protection_domain, TRAPS) {
1271 
1272   if (ik != NULL) {
1273     Symbol* class_name = ik->name();
1274 
1275     bool visible = is_shared_class_visible(
1276                             class_name, ik, class_loader, CHECK_NULL);
1277     if (!visible) {
1278       return NULL;
1279     }
1280 
1281     // Resolve the superclass and interfaces. They must be the same
1282     // as in dump time, because the layout of <ik> depends on
1283     // the specific layout of ik->super() and ik->local_interfaces().
1284     //
1285     // If unexpected superclass or interfaces are found, we cannot
1286     // load <ik> from the shared archive.
1287 
1288     if (ik->super() != NULL) {
1289       Symbol*  cn = ik->super()->name();
1290       Klass *s = resolve_super_or_fail(class_name, cn,
1291                                        class_loader, protection_domain, true, CHECK_NULL);
1292       if (s != ik->super()) {
1293         // The dynamically resolved super class is not the same as the one we used during dump time,
1294         // so we cannot use ik.
1295         return NULL;
1296       } else {
1297         assert(s->is_shared(), "must be");
1298       }
1299     }
1300 
1301     Array<Klass*>* interfaces = ik->local_interfaces();
1302     int num_interfaces = interfaces->length();
1303     for (int index = 0; index < num_interfaces; index++) {
1304       Klass* k = interfaces->at(index);
1305       Symbol*  name  = k->name();
1306       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1307       if (k != i) {
1308         // The dynamically resolved interface class is not the same as the one we used during dump time,
1309         // so we cannot use ik.
1310         return NULL;
1311       } else {
1312         assert(i->is_shared(), "must be");
1313       }
1314     }
1315 
1316     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1317         ik, class_name, class_loader, protection_domain, CHECK_NULL);
1318     if (new_ik != NULL) {
1319       // The class is changed by CFLH. Return the new class. The shared class is
1320       // not used.
1321       return new_ik;
1322     }
1323 
1324     // Adjust methods to recover missing data.  They need addresses for
1325     // interpreter entry points and their default native method address
1326     // must be reset.
1327 
1328     // Updating methods must be done under a lock so multiple
1329     // threads don't update these in parallel
1330     //
1331     // Shared classes are all currently loaded by either the bootstrap or
1332     // internal parallel class loaders, so this will never cause a deadlock
1333     // on a custom class loader lock.
1334 
1335     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1336     {
1337       HandleMark hm(THREAD);
1338       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1339       check_loader_lock_contention(lockObject, THREAD);
1340       ObjectLocker ol(lockObject, THREAD, true);
1341       // prohibited package check assumes all classes loaded from archive call
1342       // restore_unshareable_info which calls ik->set_package()
1343       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1344     }
1345 
1346     ik->print_class_load_logging(loader_data, NULL, NULL);
1347 
1348     // For boot loader, ensure that GetSystemPackage knows that a class in this
1349     // package was loaded.
1350     if (class_loader.is_null()) {
1351       int path_index = ik->shared_classpath_index();
1352       ResourceMark rm;
1353       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1354     }
1355 
1356     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1357       // Only dump the classes that can be stored into CDS archive
1358       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1359         ResourceMark rm(THREAD);
1360         classlist_file->print_cr("%s", ik->name()->as_C_string());
1361         classlist_file->flush();
1362       }
1363     }
1364 
1365     // notify a class loaded from shared object
1366     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1367   }
1368 
1369   ik->set_has_passed_fingerprint_check(false);
1370   if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1371     uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1372     uint64_t cds_fp = ik->get_stored_fingerprint();
1373     if (aot_fp != 0 && aot_fp == cds_fp) {
1374       // This class matches with a class saved in an AOT library
1375       ik->set_has_passed_fingerprint_check(true);
1376     } else {
1377       ResourceMark rm;
1378       log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1379     }
1380   }
1381   return ik;
1382 }
1383 
1384 void SystemDictionary::clear_invoke_method_table() {
1385   SymbolPropertyEntry* spe = NULL;
1386   for (int index = 0; index < _invoke_method_table->table_size(); index++) {
1387     SymbolPropertyEntry* p = _invoke_method_table->bucket(index);
1388     while (p != NULL) {
1389       spe = p;
1390       p = p->next();
1391       _invoke_method_table->free_entry(spe);
1392     }
1393   }
1394 }
1395 #endif // INCLUDE_CDS
1396 
1397 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1398 
1399   if (class_loader.is_null()) {
1400     ResourceMark rm;
1401     PackageEntry* pkg_entry = NULL;
1402     bool search_only_bootloader_append = false;
1403     ClassLoaderData *loader_data = class_loader_data(class_loader);
1404 
1405     // Find the package in the boot loader's package entry table.
1406     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1407     if (pkg_name != NULL) {
1408       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1409     }
1410 
1411     // Prior to attempting to load the class, enforce the boot loader's
1412     // visibility boundaries.
1413     if (!Universe::is_module_initialized()) {
1414       // During bootstrapping, prior to module initialization, any
1415       // class attempting to be loaded must be checked against the
1416       // java.base packages in the boot loader's PackageEntryTable.
1417       // No class outside of java.base is allowed to be loaded during
1418       // this bootstrapping window.
1419       if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1420         // Class is either in the unnamed package or in
1421         // a named package within the unnamed module.  Either
1422         // case is outside of java.base, do not attempt to
1423         // load the class post java.base definition.  If
1424         // java.base has not been defined, let the class load
1425         // and its package will be checked later by
1426         // ModuleEntryTable::verify_javabase_packages.
1427         if (ModuleEntryTable::javabase_defined()) {
1428           return NULL;
1429         }
1430       } else {
1431         // Check that the class' package is defined within java.base.
1432         ModuleEntry* mod_entry = pkg_entry->module();
1433         Symbol* mod_entry_name = mod_entry->name();
1434         if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1435           return NULL;
1436         }
1437       }
1438     } else {
1439       // After the module system has been initialized, check if the class'
1440       // package is in a module defined to the boot loader.
1441       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1442         // Class is either in the unnamed package, in a named package
1443         // within a module not defined to the boot loader or in a
1444         // a named package within the unnamed module.  In all cases,
1445         // limit visibility to search for the class only in the boot
1446         // loader's append path.
1447         search_only_bootloader_append = true;
1448       }
1449     }
1450 
1451     // Prior to bootstrapping's module initialization, never load a class outside
1452     // of the boot loader's module path
1453     assert(Universe::is_module_initialized() ||
1454            !search_only_bootloader_append,
1455            "Attempt to load a class outside of boot loader's module path");
1456 
1457     // Search the shared system dictionary for classes preloaded into the
1458     // shared spaces.
1459     InstanceKlass* k = NULL;
1460     {
1461 #if INCLUDE_CDS
1462       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1463       k = load_shared_class(class_name, class_loader, THREAD);
1464 #endif
1465     }
1466 
1467     if (k == NULL) {
1468       // Use VM class loader
1469       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1470       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1471     }
1472 
1473     // find_or_define_instance_class may return a different InstanceKlass
1474     if (k != NULL) {
1475       InstanceKlass* defined_k =
1476         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1477       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1478         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1479         assert(defined_k != NULL, "Should have a klass if there's no exception");
1480         loader_data->add_to_deallocate_list(k);
1481         k = defined_k;
1482       } else if (HAS_PENDING_EXCEPTION) {
1483         loader_data->add_to_deallocate_list(k);
1484         return NULL;
1485       }
1486     }
1487     return k;
1488   } else {
1489     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1490     ResourceMark rm(THREAD);
1491 
1492     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1493     JavaThread* jt = (JavaThread*) THREAD;
1494 
1495     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1496                                ClassLoader::perf_app_classload_selftime(),
1497                                ClassLoader::perf_app_classload_count(),
1498                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1499                                jt->get_thread_stat()->perf_timers_addr(),
1500                                PerfClassTraceTime::CLASS_LOAD);
1501 
1502     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1503     // Translate to external class name format, i.e., convert '/' chars to '.'
1504     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1505 
1506     JavaValue result(T_OBJECT);
1507 
1508     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1509 
1510     // Call public unsynchronized loadClass(String) directly for all class loaders.
1511     // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1512     // acquire a class-name based lock rather than the class loader object lock.
1513     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1514     JavaCalls::call_virtual(&result,
1515                             class_loader,
1516                             spec_klass,
1517                             vmSymbols::loadClass_name(),
1518                             vmSymbols::string_class_signature(),
1519                             string,
1520                             CHECK_NULL);
1521 
1522     assert(result.get_type() == T_OBJECT, "just checking");
1523     oop obj = (oop) result.get_jobject();
1524 
1525     // Primitive classes return null since forName() can not be
1526     // used to obtain any of the Class objects representing primitives or void
1527     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1528       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1529       // For user defined Java class loaders, check that the name returned is
1530       // the same as that requested.  This check is done for the bootstrap
1531       // loader when parsing the class file.
1532       if (class_name == k->name()) {
1533         return k;
1534       }
1535     }
1536     // Class is not found or has the wrong name, return NULL
1537     return NULL;
1538   }
1539 }
1540 
1541 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1542   EventClassDefine event;
1543   if (event.should_commit()) {
1544     event.set_definedClass(k);
1545     event.set_definingClassLoader(def_cld);
1546     event.commit();
1547   }
1548 }
1549 
1550 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1551 
1552   HandleMark hm(THREAD);
1553   ClassLoaderData* loader_data = k->class_loader_data();
1554   Handle class_loader_h(THREAD, loader_data->class_loader());
1555 
1556  // for bootstrap and other parallel classloaders don't acquire lock,
1557  // use placeholder token
1558  // If a parallelCapable class loader calls define_instance_class instead of
1559  // find_or_define_instance_class to get here, we have a timing
1560  // hole with systemDictionary updates and check_constraints
1561  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1562     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1563          compute_loader_lock_object(class_loader_h, THREAD)),
1564          "define called without lock");
1565   }
1566 
1567   // Check class-loading constraints. Throw exception if violation is detected.
1568   // Grabs and releases SystemDictionary_lock
1569   // The check_constraints/find_class call and update_dictionary sequence
1570   // must be "atomic" for a specific class/classloader pair so we never
1571   // define two different instanceKlasses for that class/classloader pair.
1572   // Existing classloaders will call define_instance_class with the
1573   // classloader lock held
1574   // Parallel classloaders will call find_or_define_instance_class
1575   // which will require a token to perform the define class
1576   Symbol*  name_h = k->name();
1577   Dictionary* dictionary = loader_data->dictionary();
1578   unsigned int d_hash = dictionary->compute_hash(name_h);
1579   check_constraints(d_hash, k, class_loader_h, true, CHECK);
1580 
1581   // Register class just loaded with class loader (placed in Vector)
1582   // Note we do this before updating the dictionary, as this can
1583   // fail with an OutOfMemoryError (if it does, we will *not* put this
1584   // class in the dictionary and will not update the class hierarchy).
1585   // JVMTI FollowReferences needs to find the classes this way.
1586   if (k->class_loader() != NULL) {
1587     methodHandle m(THREAD, Universe::loader_addClass_method());
1588     JavaValue result(T_VOID);
1589     JavaCallArguments args(class_loader_h);
1590     args.push_oop(Handle(THREAD, k->java_mirror()));
1591     JavaCalls::call(&result, m, &args, CHECK);
1592   }
1593 
1594   // Add the new class. We need recompile lock during update of CHA.
1595   {
1596     unsigned int p_hash = placeholders()->compute_hash(name_h);
1597     int p_index = placeholders()->hash_to_index(p_hash);
1598 
1599     MutexLocker mu_r(Compile_lock, THREAD);
1600 
1601     // Add to class hierarchy, initialize vtables, and do possible
1602     // deoptimizations.
1603     add_to_hierarchy(k, CHECK); // No exception, but can block
1604 
1605     // Add to systemDictionary - so other classes can see it.
1606     // Grabs and releases SystemDictionary_lock
1607     update_dictionary(d_hash, p_index, p_hash,
1608                       k, class_loader_h, THREAD);
1609   }
1610   k->eager_initialize(THREAD);
1611 
1612   // notify jvmti
1613   if (JvmtiExport::should_post_class_load()) {
1614       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1615       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1616 
1617   }
1618   post_class_define_event(k, loader_data);
1619 }
1620 
1621 // Support parallel classloading
1622 // All parallel class loaders, including bootstrap classloader
1623 // lock a placeholder entry for this class/class_loader pair
1624 // to allow parallel defines of different classes for this class loader
1625 // With AllowParallelDefine flag==true, in case they do not synchronize around
1626 // FindLoadedClass/DefineClass, calls, we check for parallel
1627 // loading for them, wait if a defineClass is in progress
1628 // and return the initial requestor's results
1629 // This flag does not apply to the bootstrap classloader.
1630 // With AllowParallelDefine flag==false, call through to define_instance_class
1631 // which will throw LinkageError: duplicate class definition.
1632 // False is the requested default.
1633 // For better performance, the class loaders should synchronize
1634 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1635 // potentially waste time reading and parsing the bytestream.
1636 // Note: VM callers should ensure consistency of k/class_name,class_loader
1637 // Be careful when modifying this code: once you have run
1638 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1639 // you need to find_and_remove it before returning.
1640 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1641 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1642                                                                InstanceKlass* k, TRAPS) {
1643 
1644   Symbol*  name_h = k->name(); // passed in class_name may be null
1645   ClassLoaderData* loader_data = class_loader_data(class_loader);
1646   Dictionary* dictionary = loader_data->dictionary();
1647 
1648   unsigned int d_hash = dictionary->compute_hash(name_h);
1649 
1650   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1651   unsigned int p_hash = placeholders()->compute_hash(name_h);
1652   int p_index = placeholders()->hash_to_index(p_hash);
1653   PlaceholderEntry* probe;
1654 
1655   {
1656     MutexLocker mu(SystemDictionary_lock, THREAD);
1657     // First check if class already defined
1658     if (is_parallelDefine(class_loader)) {
1659       InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1660       if (check != NULL) {
1661         return check;
1662       }
1663     }
1664 
1665     // Acquire define token for this class/classloader
1666     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1667     // Wait if another thread defining in parallel
1668     // All threads wait - even those that will throw duplicate class: otherwise
1669     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1670     // if other thread has not finished updating dictionary
1671     while (probe->definer() != NULL) {
1672       SystemDictionary_lock->wait();
1673     }
1674     // Only special cases allow parallel defines and can use other thread's results
1675     // Other cases fall through, and may run into duplicate defines
1676     // caught by finding an entry in the SystemDictionary
1677     if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1678         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1679         SystemDictionary_lock->notify_all();
1680 #ifdef ASSERT
1681         InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1682         assert(check != NULL, "definer missed recording success");
1683 #endif
1684         return probe->instance_klass();
1685     } else {
1686       // This thread will define the class (even if earlier thread tried and had an error)
1687       probe->set_definer(THREAD);
1688     }
1689   }
1690 
1691   define_instance_class(k, THREAD);
1692 
1693   Handle linkage_exception = Handle(); // null handle
1694 
1695   // definer must notify any waiting threads
1696   {
1697     MutexLocker mu(SystemDictionary_lock, THREAD);
1698     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1699     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1700     if (probe != NULL) {
1701       if (HAS_PENDING_EXCEPTION) {
1702         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1703         CLEAR_PENDING_EXCEPTION;
1704       } else {
1705         probe->set_instance_klass(k);
1706       }
1707       probe->set_definer(NULL);
1708       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1709       SystemDictionary_lock->notify_all();
1710     }
1711   }
1712 
1713   // Can't throw exception while holding lock due to rank ordering
1714   if (linkage_exception() != NULL) {
1715     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1716   }
1717 
1718   return k;
1719 }
1720 
1721 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1722   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1723   if (class_loader.is_null()) {
1724     return Handle(THREAD, _system_loader_lock_obj);
1725   } else {
1726     return class_loader;
1727   }
1728 }
1729 
1730 // This method is added to check how often we have to wait to grab loader
1731 // lock. The results are being recorded in the performance counters defined in
1732 // ClassLoader::_sync_systemLoaderLockContentionRate and
1733 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1734 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1735   if (!UsePerfData) {
1736     return;
1737   }
1738 
1739   assert(!loader_lock.is_null(), "NULL lock object");
1740 
1741   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1742       == ObjectSynchronizer::owner_other) {
1743     // contention will likely happen, so increment the corresponding
1744     // contention counter.
1745     if (oopDesc::equals(loader_lock(), _system_loader_lock_obj)) {
1746       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1747     } else {
1748       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1749     }
1750   }
1751 }
1752 
1753 // ----------------------------------------------------------------------------
1754 // Lookup
1755 
1756 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1757                                             Symbol* class_name,
1758                                             Dictionary* dictionary) {
1759   assert_locked_or_safepoint(SystemDictionary_lock);
1760   int index = dictionary->hash_to_index(hash);
1761   return dictionary->find_class(index, hash, class_name);
1762 }
1763 
1764 
1765 // Basic find on classes in the midst of being loaded
1766 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1767                                            ClassLoaderData* loader_data) {
1768   assert_locked_or_safepoint(SystemDictionary_lock);
1769   unsigned int p_hash = placeholders()->compute_hash(class_name);
1770   int p_index = placeholders()->hash_to_index(p_hash);
1771   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1772 }
1773 
1774 
1775 // Used for assertions and verification only
1776 // Precalculating the hash and index is an optimization because there are many lookups
1777 // before adding the class.
1778 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1779   assert_locked_or_safepoint(SystemDictionary_lock);
1780   #ifndef ASSERT
1781   guarantee(VerifyBeforeGC      ||
1782             VerifyDuringGC      ||
1783             VerifyBeforeExit    ||
1784             VerifyDuringStartup ||
1785             VerifyAfterGC, "too expensive");
1786   #endif
1787 
1788   Dictionary* dictionary = loader_data->dictionary();
1789   unsigned int d_hash = dictionary->compute_hash(class_name);
1790   return find_class(d_hash, class_name, dictionary);
1791 }
1792 
1793 
1794 // ----------------------------------------------------------------------------
1795 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1796 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1797 // before a new class is used.
1798 
1799 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1800   assert(k != NULL, "just checking");
1801   assert_locked_or_safepoint(Compile_lock);
1802 
1803   // Link into hierachy. Make sure the vtables are initialized before linking into
1804   k->append_to_sibling_list();                    // add to superklass/sibling list
1805   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1806   k->set_init_state(InstanceKlass::loaded);
1807   // Now flush all code that depended on old class hierarchy.
1808   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1809   // Also, first reinitialize vtable because it may have gotten out of synch
1810   // while the new class wasn't connected to the class hierarchy.
1811   CodeCache::flush_dependents_on(k);
1812 }
1813 
1814 // ----------------------------------------------------------------------------
1815 // GC support
1816 
1817 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1818 // Note: anonymous classes are not in the SD.
1819 bool SystemDictionary::do_unloading(GCTimer* gc_timer,
1820                                     bool do_cleaning) {
1821 
1822   bool unloading_occurred;
1823   {
1824     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1825 
1826     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1827     unloading_occurred = ClassLoaderDataGraph::do_unloading(do_cleaning);
1828   }
1829 
1830   if (unloading_occurred) {
1831     GCTraceTime(Debug, gc, phases) t("Dictionary", gc_timer);
1832     constraints()->purge_loader_constraints();
1833     resolution_errors()->purge_resolution_errors();
1834   }
1835 
1836   {
1837     GCTraceTime(Debug, gc, phases) t("ProtectionDomainCacheTable", gc_timer);
1838     // Oops referenced by the protection domain cache table may get unreachable independently
1839     // of the class loader (eg. cached protection domain oops). So we need to
1840     // explicitly unlink them here.
1841     _pd_cache_table->unlink();
1842   }
1843 
1844   if (do_cleaning) {
1845     GCTraceTime(Debug, gc, phases) t("ResolvedMethodTable", gc_timer);
1846     ResolvedMethodTable::unlink();
1847   }
1848 
1849   return unloading_occurred;
1850 }
1851 
1852 void SystemDictionary::oops_do(OopClosure* f) {
1853   f->do_oop(&_java_system_loader);
1854   f->do_oop(&_java_platform_loader);
1855   f->do_oop(&_system_loader_lock_obj);
1856   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1857 
1858   // Visit extra methods
1859   invoke_method_table()->oops_do(f);
1860 }
1861 
1862 // CDS: scan and relocate all classes in the system dictionary.
1863 void SystemDictionary::classes_do(MetaspaceClosure* it) {
1864   ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(it);
1865 }
1866 
1867 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1868 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1869   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1870     it->push(well_known_klass_addr((WKID)id));
1871   }
1872 }
1873 
1874 void SystemDictionary::methods_do(void f(Method*)) {
1875   // Walk methods in loaded classes
1876   ClassLoaderDataGraph::methods_do(f);
1877   // Walk method handle intrinsics
1878   invoke_method_table()->methods_do(f);
1879 }
1880 
1881 class RemoveClassesClosure : public CLDClosure {
1882   public:
1883     void do_cld(ClassLoaderData* cld) {
1884       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
1885         cld->dictionary()->remove_classes_in_error_state();
1886       }
1887     }
1888 };
1889 
1890 void SystemDictionary::remove_classes_in_error_state() {
1891   ClassLoaderData::the_null_class_loader_data()->dictionary()->remove_classes_in_error_state();
1892   RemoveClassesClosure rcc;
1893   ClassLoaderDataGraph::cld_do(&rcc);
1894 }
1895 
1896 // ----------------------------------------------------------------------------
1897 // Initialization
1898 
1899 void SystemDictionary::initialize(TRAPS) {
1900   // Allocate arrays
1901   _placeholders        = new PlaceholderTable(_placeholder_table_size);
1902   _number_of_modifications = 0;
1903   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1904   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1905   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1906   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1907 
1908   // Allocate private object used as system class loader lock
1909   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1910   // Initialize basic classes
1911   initialize_preloaded_classes(CHECK);
1912 }
1913 
1914 // Compact table of directions on the initialization of klasses:
1915 static const short wk_init_info[] = {
1916   #define WK_KLASS_INIT_INFO(name, symbol, option) \
1917     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1918           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1919       | (int)SystemDictionary::option ),
1920   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1921   #undef WK_KLASS_INIT_INFO
1922   0
1923 };
1924 
1925 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1926   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1927   int  info = wk_init_info[id - FIRST_WKID];
1928   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
1929   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1930   InstanceKlass** klassp = &_well_known_klasses[id];
1931 
1932   bool must_load;
1933 #if INCLUDE_JVMCI
1934   if (EnableJVMCI) {
1935     // If JVMCI is enabled we require its classes to be found.
1936     must_load = (init_opt < SystemDictionary::Opt) || (init_opt == SystemDictionary::Jvmci);
1937   } else
1938 #endif
1939   {
1940     must_load = (init_opt < SystemDictionary::Opt);
1941   }
1942 
1943   if ((*klassp) == NULL) {
1944     Klass* k;
1945     if (must_load) {
1946       k = resolve_or_fail(symbol, true, CHECK_0); // load required class
1947     } else {
1948       k = resolve_or_null(symbol,       CHECK_0); // load optional klass
1949     }
1950     (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
1951   }
1952   return ((*klassp) != NULL);
1953 }
1954 
1955 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1956   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1957   for (int id = (int)start_id; id < (int)limit_id; id++) {
1958     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1959     int info = wk_init_info[id - FIRST_WKID];
1960     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
1961     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1962 
1963     initialize_wk_klass((WKID)id, opt, CHECK);
1964   }
1965 
1966   // move the starting value forward to the limit:
1967   start_id = limit_id;
1968 }
1969 
1970 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1971   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1972 
1973   // Create the ModuleEntry for java.base.  This call needs to be done here,
1974   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
1975   ClassLoader::classLoader_init2(CHECK);
1976 
1977   // Preload commonly used klasses
1978   WKID scan = FIRST_WKID;
1979   // first do Object, then String, Class
1980 #if INCLUDE_CDS
1981   if (UseSharedSpaces) {
1982     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1983     // Initialize the constant pool for the Object_class
1984     Object_klass()->constants()->restore_unshareable_info(CHECK);
1985     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1986   } else
1987 #endif
1988   {
1989     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1990   }
1991 
1992   // Calculate offsets for String and Class classes since they are loaded and
1993   // can be used after this point.
1994   java_lang_String::compute_offsets();
1995   java_lang_Class::compute_offsets();
1996 
1997   // Fixup mirrors for classes loaded before java.lang.Class.
1998   // These calls iterate over the objects currently in the perm gen
1999   // so calling them at this point is matters (not before when there
2000   // are fewer objects and not later after there are more objects
2001   // in the perm gen.
2002   Universe::initialize_basic_type_mirrors(CHECK);
2003   Universe::fixup_mirrors(CHECK);
2004 
2005   // do a bunch more:
2006   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2007 
2008   // Preload ref klasses and set reference types
2009   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2010   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2011 
2012   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2013   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2014   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2015   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2016   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2017 
2018   // JSR 292 classes
2019   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2020   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2021   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
2022   initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
2023   initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
2024 
2025   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2026   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2027   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2028   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2029   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2030   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2031   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2032   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2033   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2034   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2035 
2036   { // Compute whether we should use checkPackageAccess or NOT
2037     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2038     _has_checkPackageAccess = (method != NULL);
2039   }
2040 }
2041 
2042 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2043 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2044 BasicType SystemDictionary::box_klass_type(Klass* k) {
2045   assert(k != NULL, "");
2046   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2047     if (_box_klasses[i] == k)
2048       return (BasicType)i;
2049   }
2050   return T_OBJECT;
2051 }
2052 
2053 // Constraints on class loaders. The details of the algorithm can be
2054 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2055 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2056 // that the dictionary needs to maintain a set of contraints that
2057 // must be satisfied by all classes in the dictionary.
2058 // if defining is true, then LinkageError if already in dictionary
2059 // if initiating loader, then ok if InstanceKlass matches existing entry
2060 
2061 void SystemDictionary::check_constraints(unsigned int d_hash,
2062                                          InstanceKlass* k,
2063                                          Handle class_loader,
2064                                          bool defining,
2065                                          TRAPS) {
2066   ResourceMark rm(THREAD);
2067   stringStream ss;
2068   bool throwException = false;
2069 
2070   {
2071     Symbol *name = k->name();
2072     ClassLoaderData *loader_data = class_loader_data(class_loader);
2073 
2074     MutexLocker mu(SystemDictionary_lock, THREAD);
2075 
2076     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2077     if (check != NULL) {
2078       // If different InstanceKlass - duplicate class definition,
2079       // else - ok, class loaded by a different thread in parallel.
2080       // We should only have found it if it was done loading and ok to use.
2081       // The dictionary only holds instance classes, placeholders
2082       // also hold array classes.
2083 
2084       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2085       if ((defining == true) || (k != check)) {
2086         throwException = true;
2087         ss.print("loader %s", java_lang_ClassLoader::describe_external(class_loader()));
2088         ss.print(" attempted duplicate %s definition for %s.",
2089                  k->external_kind(), k->external_name());
2090       } else {
2091         return;
2092       }
2093     }
2094 
2095 #ifdef ASSERT
2096     Symbol* ph_check = find_placeholder(name, loader_data);
2097     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2098 #endif
2099 
2100     if (throwException == false) {
2101       if (constraints()->check_or_update(k, class_loader, name) == false) {
2102         throwException = true;
2103         ss.print("loader constraint violation: loader %s",
2104                  java_lang_ClassLoader::describe_external(class_loader()));
2105         ss.print(" wants to load %s %s.",
2106                  k->external_kind(), k->external_name());
2107         Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2108         if (existing_klass->class_loader() != class_loader()) {
2109           ss.print(" A different %s with the same name was previously loaded by %s.",
2110                    existing_klass->external_kind(),
2111                    java_lang_ClassLoader::describe_external(existing_klass->class_loader()));



2112         }
2113       }
2114     }
2115   }
2116 
2117   // Throw error now if needed (cannot throw while holding
2118   // SystemDictionary_lock because of rank ordering)
2119   if (throwException == true) {
2120     THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2121   }
2122 }
2123 
2124 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2125 // have been called.
2126 void SystemDictionary::update_dictionary(unsigned int d_hash,
2127                                          int p_index, unsigned int p_hash,
2128                                          InstanceKlass* k,
2129                                          Handle class_loader,
2130                                          TRAPS) {
2131   // Compile_lock prevents systemDictionary updates during compilations
2132   assert_locked_or_safepoint(Compile_lock);
2133   Symbol*  name  = k->name();
2134   ClassLoaderData *loader_data = class_loader_data(class_loader);
2135 
2136   {
2137     MutexLocker mu1(SystemDictionary_lock, THREAD);
2138 
2139     // See whether biased locking is enabled and if so set it for this
2140     // klass.
2141     // Note that this must be done past the last potential blocking
2142     // point / safepoint. We enable biased locking lazily using a
2143     // VM_Operation to iterate the SystemDictionary and installing the
2144     // biasable mark word into each InstanceKlass's prototype header.
2145     // To avoid race conditions where we accidentally miss enabling the
2146     // optimization for one class in the process of being added to the
2147     // dictionary, we must not safepoint after the test of
2148     // BiasedLocking::enabled().
2149     if (UseBiasedLocking && BiasedLocking::enabled()) {
2150       // Set biased locking bit for all loaded classes; it will be
2151       // cleared if revocation occurs too often for this type
2152       // NOTE that we must only do this when the class is initally
2153       // defined, not each time it is referenced from a new class loader
2154       if (oopDesc::equals(k->class_loader(), class_loader())) {
2155         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2156       }
2157     }
2158 
2159     // Make a new dictionary entry.
2160     Dictionary* dictionary = loader_data->dictionary();
2161     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2162     if (sd_check == NULL) {
2163       dictionary->add_klass(d_hash, name, k);
2164       notice_modification();
2165     }
2166   #ifdef ASSERT
2167     sd_check = find_class(d_hash, name, dictionary);
2168     assert (sd_check != NULL, "should have entry in dictionary");
2169     // Note: there may be a placeholder entry: for circularity testing
2170     // or for parallel defines
2171   #endif
2172     SystemDictionary_lock->notify_all();
2173   }
2174 }
2175 
2176 
2177 // Try to find a class name using the loader constraints.  The
2178 // loader constraints might know about a class that isn't fully loaded
2179 // yet and these will be ignored.
2180 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2181                     Symbol* class_name, Handle class_loader, TRAPS) {
2182 
2183   // First see if it has been loaded directly.
2184   // Force the protection domain to be null.  (This removes protection checks.)
2185   Handle no_protection_domain;
2186   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2187                                               no_protection_domain, CHECK_NULL);
2188   if (klass != NULL)
2189     return klass;
2190 
2191   // Now look to see if it has been loaded elsewhere, and is subject to
2192   // a loader constraint that would require this loader to return the
2193   // klass that is already loaded.
2194   if (FieldType::is_array(class_name)) {
2195     // For array classes, their Klass*s are not kept in the
2196     // constraint table. The element Klass*s are.
2197     FieldArrayInfo fd;
2198     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2199     if (t != T_OBJECT) {
2200       klass = Universe::typeArrayKlassObj(t);
2201     } else {
2202       MutexLocker mu(SystemDictionary_lock, THREAD);
2203       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2204     }
2205     // If element class already loaded, allocate array klass
2206     if (klass != NULL) {
2207       klass = klass->array_klass_or_null(fd.dimension());
2208     }
2209   } else {
2210     MutexLocker mu(SystemDictionary_lock, THREAD);
2211     // Non-array classes are easy: simply check the constraint table.
2212     klass = constraints()->find_constrained_klass(class_name, class_loader);
2213   }
2214 
2215   return klass;
2216 }
2217 
2218 
2219 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2220                                              Handle class_loader1,
2221                                              Handle class_loader2,
2222                                              Thread* THREAD) {
2223   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2224   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2225 
2226   Symbol* constraint_name = NULL;
2227   if (!FieldType::is_array(class_name)) {
2228     constraint_name = class_name;
2229   } else {
2230     // For array classes, their Klass*s are not kept in the
2231     // constraint table. The element classes are.
2232     FieldArrayInfo fd;
2233     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2234     // primitive types always pass
2235     if (t != T_OBJECT) {
2236       return true;
2237     } else {
2238       constraint_name = fd.object_key();
2239     }
2240   }
2241 
2242   Dictionary* dictionary1 = loader_data1->dictionary();
2243   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2244 
2245   Dictionary* dictionary2 = loader_data2->dictionary();
2246   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2247 
2248   {
2249     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2250     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2251     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2252     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2253                                     klass2, class_loader2);
2254   }
2255 }
2256 
2257 // Add entry to resolution error table to record the error when the first
2258 // attempt to resolve a reference to a class has failed.
2259 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2260                                             Symbol* error, Symbol* message) {
2261   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2262   int index = resolution_errors()->hash_to_index(hash);
2263   {
2264     MutexLocker ml(SystemDictionary_lock, Thread::current());
2265     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2266   }
2267 }
2268 
2269 // Delete a resolution error for RedefineClasses for a constant pool is going away
2270 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2271   resolution_errors()->delete_entry(pool);
2272 }
2273 
2274 // Lookup resolution error table. Returns error if found, otherwise NULL.
2275 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2276                                                 Symbol** message) {
2277   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2278   int index = resolution_errors()->hash_to_index(hash);
2279   {
2280     MutexLocker ml(SystemDictionary_lock, Thread::current());
2281     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2282     if (entry != NULL) {
2283       *message = entry->message();
2284       return entry->error();
2285     } else {
2286       return NULL;
2287     }
2288   }
2289 }
2290 
2291 
2292 // Signature constraints ensure that callers and callees agree about
2293 // the meaning of type names in their signatures.  This routine is the
2294 // intake for constraints.  It collects them from several places:
2295 //
2296 //  * LinkResolver::resolve_method (if check_access is true) requires
2297 //    that the resolving class (the caller) and the defining class of
2298 //    the resolved method (the callee) agree on each type in the
2299 //    method's signature.
2300 //
2301 //  * LinkResolver::resolve_interface_method performs exactly the same
2302 //    checks.
2303 //
2304 //  * LinkResolver::resolve_field requires that the constant pool
2305 //    attempting to link to a field agree with the field's defining
2306 //    class about the type of the field signature.
2307 //
2308 //  * klassVtable::initialize_vtable requires that, when a class
2309 //    overrides a vtable entry allocated by a superclass, that the
2310 //    overriding method (i.e., the callee) agree with the superclass
2311 //    on each type in the method's signature.
2312 //
2313 //  * klassItable::initialize_itable requires that, when a class fills
2314 //    in its itables, for each non-abstract method installed in an
2315 //    itable, the method (i.e., the callee) agree with the interface
2316 //    on each type in the method's signature.
2317 //
2318 // All those methods have a boolean (check_access, checkconstraints)
2319 // which turns off the checks.  This is used from specialized contexts
2320 // such as bootstrapping, dumping, and debugging.
2321 //
2322 // No direct constraint is placed between the class and its
2323 // supertypes.  Constraints are only placed along linked relations
2324 // between callers and callees.  When a method overrides or implements
2325 // an abstract method in a supertype (superclass or interface), the
2326 // constraints are placed as if the supertype were the caller to the
2327 // overriding method.  (This works well, since callers to the
2328 // supertype have already established agreement between themselves and
2329 // the supertype.)  As a result of all this, a class can disagree with
2330 // its supertype about the meaning of a type name, as long as that
2331 // class neither calls a relevant method of the supertype, nor is
2332 // called (perhaps via an override) from the supertype.
2333 //
2334 //
2335 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2336 //
2337 // Make sure all class components (including arrays) in the given
2338 // signature will be resolved to the same class in both loaders.
2339 // Returns the name of the type that failed a loader constraint check, or
2340 // NULL if no constraint failed.  No exception except OOME is thrown.
2341 // Arrays are not added to the loader constraint table, their elements are.
2342 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2343                                                Handle loader1, Handle loader2,
2344                                                bool is_method, TRAPS)  {
2345   // Nothing to do if loaders are the same.
2346   if (oopDesc::equals(loader1(), loader2())) {
2347     return NULL;
2348   }
2349 
2350   SignatureStream sig_strm(signature, is_method);
2351   while (!sig_strm.is_done()) {
2352     if (sig_strm.is_object()) {
2353       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2354       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2355         return sig;
2356       }
2357     }
2358     sig_strm.next();
2359   }
2360   return NULL;
2361 }
2362 
2363 
2364 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2365                                                             Symbol* signature,
2366                                                             TRAPS) {
2367   methodHandle empty;
2368   assert(MethodHandles::is_signature_polymorphic(iid) &&
2369          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2370          iid != vmIntrinsics::_invokeGeneric,
2371          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2372 
2373   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2374   int          index = invoke_method_table()->hash_to_index(hash);
2375   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2376   methodHandle m;
2377   if (spe == NULL || spe->method() == NULL) {
2378     spe = NULL;
2379     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2380     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2381     if (!Arguments::is_interpreter_only()) {
2382       // Generate a compiled form of the MH intrinsic.
2383       AdapterHandlerLibrary::create_native_wrapper(m);
2384       // Check if have the compiled code.
2385       if (!m->has_compiled_code()) {
2386         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2387                    "Out of space in CodeCache for method handle intrinsic", empty);
2388       }
2389     }
2390     // Now grab the lock.  We might have to throw away the new method,
2391     // if a racing thread has managed to install one at the same time.
2392     {
2393       MutexLocker ml(SystemDictionary_lock, THREAD);
2394       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2395       if (spe == NULL)
2396         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2397       if (spe->method() == NULL)
2398         spe->set_method(m());
2399     }
2400   }
2401 
2402   assert(spe != NULL && spe->method() != NULL, "");
2403   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2404          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2405          "MH intrinsic invariant");
2406   return spe->method();
2407 }
2408 
2409 // Helper for unpacking the return value from linkMethod and linkCallSite.
2410 static methodHandle unpack_method_and_appendix(Handle mname,
2411                                                Klass* accessing_klass,
2412                                                objArrayHandle appendix_box,
2413                                                Handle* appendix_result,
2414                                                TRAPS) {
2415   methodHandle empty;
2416   if (mname.not_null()) {
2417     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2418     if (m != NULL) {
2419       oop appendix = appendix_box->obj_at(0);
2420       if (TraceMethodHandles) {
2421     #ifndef PRODUCT
2422         ttyLocker ttyl;
2423         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2424         m->print();
2425         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2426         tty->cr();
2427     #endif //PRODUCT
2428       }
2429       (*appendix_result) = Handle(THREAD, appendix);
2430       // the target is stored in the cpCache and if a reference to this
2431       // MemberName is dropped we need a way to make sure the
2432       // class_loader containing this method is kept alive.
2433       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2434       this_key->record_dependency(m->method_holder());
2435       return methodHandle(THREAD, m);
2436     }
2437   }
2438   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2439   return empty;
2440 }
2441 
2442 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2443                                                           Symbol* name,
2444                                                           Symbol* signature,
2445                                                           Klass* accessing_klass,
2446                                                           Handle *appendix_result,
2447                                                           Handle *method_type_result,
2448                                                           TRAPS) {
2449   methodHandle empty;
2450   assert(THREAD->can_call_java() ,"");
2451   Handle method_type =
2452     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2453 
2454   int ref_kind = JVM_REF_invokeVirtual;
2455   oop name_oop = StringTable::intern(name, CHECK_(empty));
2456   Handle name_str (THREAD, name_oop);
2457   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2458   assert(appendix_box->obj_at(0) == NULL, "");
2459 
2460   // This should not happen.  JDK code should take care of that.
2461   if (accessing_klass == NULL || method_type.is_null()) {
2462     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2463   }
2464 
2465   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2466   JavaCallArguments args;
2467   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2468   args.push_int(ref_kind);
2469   args.push_oop(Handle(THREAD, klass->java_mirror()));
2470   args.push_oop(name_str);
2471   args.push_oop(method_type);
2472   args.push_oop(appendix_box);
2473   JavaValue result(T_OBJECT);
2474   JavaCalls::call_static(&result,
2475                          SystemDictionary::MethodHandleNatives_klass(),
2476                          vmSymbols::linkMethod_name(),
2477                          vmSymbols::linkMethod_signature(),
2478                          &args, CHECK_(empty));
2479   Handle mname(THREAD, (oop) result.get_jobject());
2480   (*method_type_result) = method_type;
2481   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2482 }
2483 
2484 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2485 // We must ensure that all class loaders everywhere will reach this class, for any client.
2486 // This is a safe bet for public classes in java.lang, such as Object and String.
2487 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2488 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2489 static bool is_always_visible_class(oop mirror) {
2490   Klass* klass = java_lang_Class::as_Klass(mirror);
2491   if (klass->is_objArray_klass()) {
2492     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2493   }
2494   if (klass->is_typeArray_klass()) {
2495     return true; // primitive array
2496   }
2497   assert(klass->is_instance_klass(), "%s", klass->external_name());
2498   return klass->is_public() &&
2499          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2500           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2501 }
2502 
2503 
2504 // Return the Java mirror (java.lang.Class instance) for a single-character
2505 // descriptor.  This result, when available, is the same as produced by the
2506 // heavier API point of the same name that takes a Symbol.
2507 oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
2508   return java_lang_Class::primitive_mirror(char2type(signature_char));
2509 }
2510 
2511 // Find or construct the Java mirror (java.lang.Class instance) for a
2512 // for the given field type signature, as interpreted relative to the
2513 // given class loader.  Handles primitives, void, references, arrays,
2514 // and all other reflectable types, except method types.
2515 // N.B.  Code in reflection should use this entry point.
2516 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2517                                                    Klass* accessing_klass,
2518                                                    Handle class_loader,
2519                                                    Handle protection_domain,
2520                                                    SignatureStream::FailureMode failure_mode,
2521                                                    TRAPS) {
2522   Handle empty;
2523 
2524   assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2525          "one or the other, or perhaps neither");
2526 
2527   Symbol* type = signature;
2528 
2529   // What we have here must be a valid field descriptor,
2530   // and all valid field descriptors are supported.
2531   // Produce the same java.lang.Class that reflection reports.
2532   if (type->utf8_length() == 1) {
2533 
2534     // It's a primitive.  (Void has a primitive mirror too.)
2535     char ch = (char) type->byte_at(0);
2536     assert(is_java_primitive(char2type(ch)) || ch == 'V', "");
2537     return Handle(THREAD, find_java_mirror_for_type(ch));
2538 
2539   } else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
2540 
2541     // It's a reference type.
2542     if (accessing_klass != NULL) {
2543       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2544       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2545     }
2546     Klass* constant_type_klass;
2547     if (failure_mode == SignatureStream::ReturnNull) {
2548       constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
2549                                             CHECK_(empty));
2550     } else {
2551       bool throw_error = (failure_mode == SignatureStream::NCDFError);
2552       constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
2553                                             throw_error, CHECK_(empty));
2554     }
2555     if (constant_type_klass == NULL) {
2556       return Handle();  // report failure this way
2557     }
2558     Handle mirror(THREAD, constant_type_klass->java_mirror());
2559 
2560     // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2561     if (accessing_klass != NULL) {
2562       Klass* sel_klass = constant_type_klass;
2563       bool fold_type_to_class = true;
2564       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2565                                               fold_type_to_class, CHECK_(empty));
2566     }
2567 
2568     return mirror;
2569 
2570   }
2571 
2572   // Fall through to an error.
2573   assert(false, "unsupported mirror syntax");
2574   THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2575 }
2576 
2577 
2578 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2579 // signature, as interpreted relative to the given class loader.
2580 // Because of class loader constraints, all method handle usage must be
2581 // consistent with this loader.
2582 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2583                                                  Klass* accessing_klass,
2584                                                  TRAPS) {
2585   Handle empty;
2586   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2587   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2588   int          index = invoke_method_table()->hash_to_index(hash);
2589   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2590   if (spe != NULL && spe->method_type() != NULL) {
2591     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2592     return Handle(THREAD, spe->method_type());
2593   } else if (!THREAD->can_call_java()) {
2594     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2595     return Handle();  // do not attempt from within compiler, unless it was cached
2596   }
2597 
2598   Handle class_loader, protection_domain;
2599   if (accessing_klass != NULL) {
2600     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2601     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2602   }
2603   bool can_be_cached = true;
2604   int npts = ArgumentCount(signature).size();
2605   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2606   int arg = 0;
2607   Handle rt; // the return type from the signature
2608   ResourceMark rm(THREAD);
2609   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2610     oop mirror = NULL;
2611     if (can_be_cached) {
2612       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2613       mirror = ss.as_java_mirror(Handle(), Handle(),
2614                                  SignatureStream::ReturnNull, CHECK_(empty));
2615       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2616         // Fall back to accessing_klass context.
2617         can_be_cached = false;
2618       }
2619     }
2620     if (!can_be_cached) {
2621       // Resolve, throwing a real error if it doesn't work.
2622       mirror = ss.as_java_mirror(class_loader, protection_domain,
2623                                  SignatureStream::NCDFError, CHECK_(empty));
2624     }
2625     assert(mirror != NULL, "%s", ss.as_symbol(THREAD)->as_C_string());
2626     if (ss.at_return_type())
2627       rt = Handle(THREAD, mirror);
2628     else
2629       pts->obj_at_put(arg++, mirror);
2630 
2631     // Check accessibility.
2632     if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2633       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2634       mirror = NULL;  // safety
2635       // Emulate ConstantPool::verify_constant_pool_resolve.
2636       bool fold_type_to_class = true;
2637       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2638                                               fold_type_to_class, CHECK_(empty));
2639     }
2640   }
2641   assert(arg == npts, "");
2642 
2643   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2644   JavaCallArguments args(Handle(THREAD, rt()));
2645   args.push_oop(pts);
2646   JavaValue result(T_OBJECT);
2647   JavaCalls::call_static(&result,
2648                          SystemDictionary::MethodHandleNatives_klass(),
2649                          vmSymbols::findMethodHandleType_name(),
2650                          vmSymbols::findMethodHandleType_signature(),
2651                          &args, CHECK_(empty));
2652   Handle method_type(THREAD, (oop) result.get_jobject());
2653 
2654   if (can_be_cached) {
2655     // We can cache this MethodType inside the JVM.
2656     MutexLocker ml(SystemDictionary_lock, THREAD);
2657     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2658     if (spe == NULL)
2659       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2660     if (spe->method_type() == NULL) {
2661       spe->set_method_type(method_type());
2662     }
2663   }
2664 
2665   // report back to the caller with the MethodType
2666   return method_type;
2667 }
2668 
2669 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2670                                                 Klass* accessing_klass,
2671                                                 TRAPS) {
2672   Handle empty;
2673   ResourceMark rm(THREAD);
2674   SignatureStream ss(signature, /*is_method=*/ false);
2675   if (!ss.is_done()) {
2676     Handle class_loader, protection_domain;
2677     if (accessing_klass != NULL) {
2678       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2679       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2680     }
2681     oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2682     ss.next();
2683     if (ss.is_done()) {
2684       return Handle(THREAD, mirror);
2685     }
2686   }
2687   return empty;
2688 }
2689 
2690 // Ask Java code to find or construct a method handle constant.
2691 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2692                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2693                                                      Klass* callee,
2694                                                      Symbol* name,
2695                                                      Symbol* signature,
2696                                                      TRAPS) {
2697   Handle empty;
2698   if (caller == NULL) {
2699     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2700   }
2701   Handle name_str      = java_lang_String::create_from_symbol(name,      CHECK_(empty));
2702   Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2703 
2704   // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2705   Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2706   java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2707   java_lang_invoke_MemberName::set_name (mname(), name_str());
2708   java_lang_invoke_MemberName::set_type (mname(), signature_str());
2709   java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2710 
2711   if (ref_kind == JVM_REF_invokeVirtual &&
2712       MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2713     // Skip resolution for public signature polymorphic methods such as
2714     // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2715     // They require appendix argument which MemberName resolution doesn't handle.
2716     // There's special logic on JDK side to handle them
2717     // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2718   } else {
2719     MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2720   }
2721 
2722   // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2723   Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2724 
2725   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2726   JavaCallArguments args;
2727   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2728   args.push_int(ref_kind);
2729   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2730   args.push_oop(name_str);
2731   args.push_oop(type);
2732   JavaValue result(T_OBJECT);
2733   JavaCalls::call_static(&result,
2734                          SystemDictionary::MethodHandleNatives_klass(),
2735                          vmSymbols::linkMethodHandleConstant_name(),
2736                          vmSymbols::linkMethodHandleConstant_signature(),
2737                          &args, CHECK_(empty));
2738   return Handle(THREAD, (oop) result.get_jobject());
2739 }
2740 
2741 // Ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry
2742 Handle SystemDictionary::link_dynamic_constant(Klass* caller,
2743                                                int condy_index,
2744                                                Handle bootstrap_specifier,
2745                                                Symbol* name,
2746                                                Symbol* type,
2747                                                TRAPS) {
2748   Handle empty;
2749   Handle bsm, info;
2750   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2751     bsm = bootstrap_specifier;
2752   } else {
2753     assert(bootstrap_specifier->is_objArray(), "");
2754     objArrayOop args = (objArrayOop) bootstrap_specifier();
2755     assert(args->length() == 2, "");
2756     bsm  = Handle(THREAD, args->obj_at(0));
2757     info = Handle(THREAD, args->obj_at(1));
2758   }
2759   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2760             "caller must supply a valid BSM");
2761 
2762   // This should not happen.  JDK code should take care of that.
2763   if (caller == NULL) {
2764     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad dynamic constant", empty);
2765   }
2766 
2767   Handle constant_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2768 
2769   // Resolve the constant type in the context of the caller class
2770   Handle type_mirror = find_java_mirror_for_type(type, caller, SignatureStream::NCDFError,
2771                                                  CHECK_(empty));
2772 
2773   // call java.lang.invoke.MethodHandleNatives::linkConstantDyanmic(caller, condy_index, bsm, type, info)
2774   JavaCallArguments args;
2775   args.push_oop(Handle(THREAD, caller->java_mirror()));
2776   args.push_int(condy_index);
2777   args.push_oop(bsm);
2778   args.push_oop(constant_name);
2779   args.push_oop(type_mirror);
2780   args.push_oop(info);
2781   JavaValue result(T_OBJECT);
2782   JavaCalls::call_static(&result,
2783                          SystemDictionary::MethodHandleNatives_klass(),
2784                          vmSymbols::linkDynamicConstant_name(),
2785                          vmSymbols::linkDynamicConstant_signature(),
2786                          &args, CHECK_(empty));
2787 
2788   return Handle(THREAD, (oop) result.get_jobject());
2789 }
2790 
2791 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2792 // name and signature, as interpreted relative to the given class loader.
2793 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller,
2794                                                               int indy_index,
2795                                                               Handle bootstrap_specifier,
2796                                                               Symbol* name,
2797                                                               Symbol* type,
2798                                                               Handle *appendix_result,
2799                                                               Handle *method_type_result,
2800                                                               TRAPS) {
2801   methodHandle empty;
2802   Handle bsm, info;
2803   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2804     bsm = bootstrap_specifier;
2805   } else {
2806     objArrayOop args = (objArrayOop) bootstrap_specifier();
2807     assert(args->length() == 2, "");
2808     bsm  = Handle(THREAD, args->obj_at(0));
2809     info = Handle(THREAD, args->obj_at(1));
2810   }
2811   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2812             "caller must supply a valid BSM");
2813 
2814   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2815   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2816 
2817   // This should not happen.  JDK code should take care of that.
2818   if (caller == NULL || method_type.is_null()) {
2819     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2820   }
2821 
2822   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2823   assert(appendix_box->obj_at(0) == NULL, "");
2824 
2825   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2826   JavaCallArguments args;
2827   args.push_oop(Handle(THREAD, caller->java_mirror()));
2828   args.push_int(indy_index);
2829   args.push_oop(bsm);
2830   args.push_oop(method_name);
2831   args.push_oop(method_type);
2832   args.push_oop(info);
2833   args.push_oop(appendix_box);
2834   JavaValue result(T_OBJECT);
2835   JavaCalls::call_static(&result,
2836                          SystemDictionary::MethodHandleNatives_klass(),
2837                          vmSymbols::linkCallSite_name(),
2838                          vmSymbols::linkCallSite_signature(),
2839                          &args, CHECK_(empty));
2840   Handle mname(THREAD, (oop) result.get_jobject());
2841   (*method_type_result) = method_type;
2842   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2843 }
2844 
2845 // Protection domain cache table handling
2846 
2847 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2848   return _pd_cache_table->get(protection_domain);
2849 }
2850 
2851 #if INCLUDE_CDS
2852 void SystemDictionary::reorder_dictionary_for_sharing() {
2853   ClassLoaderData::the_null_class_loader_data()->dictionary()->reorder_dictionary_for_sharing();
2854 }
2855 #endif
2856 
2857 size_t SystemDictionary::count_bytes_for_buckets() {
2858   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_buckets();
2859 }
2860 
2861 size_t SystemDictionary::count_bytes_for_table() {
2862   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_table();
2863 }
2864 
2865 void SystemDictionary::copy_buckets(char* top, char* end) {
2866   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_buckets(top, end);
2867 }
2868 
2869 void SystemDictionary::copy_table(char* top, char* end) {
2870   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_table(top, end);
2871 }
2872 
2873 // ----------------------------------------------------------------------------
2874 void SystemDictionary::print_shared(outputStream *st) {
2875   shared_dictionary()->print_on(st);
2876 }
2877 
2878 void SystemDictionary::print_on(outputStream *st) {
2879   if (shared_dictionary() != NULL) {
2880     st->print_cr("Shared Dictionary");
2881     shared_dictionary()->print_on(st);
2882     st->cr();
2883   }
2884 
2885   GCMutexLocker mu(SystemDictionary_lock);
2886 
2887   ClassLoaderDataGraph::print_dictionary(st);
2888 
2889   // Placeholders
2890   placeholders()->print_on(st);
2891   st->cr();
2892 
2893   // loader constraints - print under SD_lock
2894   constraints()->print_on(st);
2895   st->cr();
2896 
2897   _pd_cache_table->print_on(st);
2898   st->cr();
2899 }
2900 
2901 void SystemDictionary::verify() {
2902   guarantee(constraints() != NULL,
2903             "Verify of loader constraints failed");
2904   guarantee(placeholders()->number_of_entries() >= 0,
2905             "Verify of placeholders failed");
2906 
2907   GCMutexLocker mu(SystemDictionary_lock);
2908 
2909   // Verify dictionary
2910   ClassLoaderDataGraph::verify_dictionary();
2911 
2912   placeholders()->verify();
2913 
2914   // Verify constraint table
2915   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2916   constraints()->verify(placeholders());
2917 
2918   _pd_cache_table->verify();
2919 }
2920 
2921 void SystemDictionary::dump(outputStream *st, bool verbose) {
2922   assert_locked_or_safepoint(SystemDictionary_lock);
2923   if (verbose) {
2924     print_on(st);
2925   } else {
2926     if (shared_dictionary() != NULL) {
2927       shared_dictionary()->print_table_statistics(st, "Shared Dictionary");
2928     }
2929     ClassLoaderDataGraph::print_dictionary_statistics(st);
2930     placeholders()->print_table_statistics(st, "Placeholder Table");
2931     constraints()->print_table_statistics(st, "LoaderConstraints Table");
2932     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
2933   }
2934 }
2935 
2936 // Utility for dumping dictionaries.
2937 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2938                                  DCmdWithParser(output, heap),
2939   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2940            "BOOLEAN", false, "false") {
2941   _dcmdparser.add_dcmd_option(&_verbose);
2942 }
2943 
2944 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2945   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2946                          _verbose.value());
2947   VMThread::execute(&dumper);
2948 }
2949 
2950 int SystemDictionaryDCmd::num_arguments() {
2951   ResourceMark rm;
2952   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
2953   if (dcmd != NULL) {
2954     DCmdMark mark(dcmd);
2955     return dcmd->_dcmdparser.num_arguments();
2956   } else {
2957     return 0;
2958   }
2959 }
2960 
2961 class CombineDictionariesClosure : public CLDClosure {
2962   private:
2963     Dictionary* _master_dictionary;
2964   public:
2965     CombineDictionariesClosure(Dictionary* master_dictionary) :
2966       _master_dictionary(master_dictionary) {}
2967     void do_cld(ClassLoaderData* cld) {
2968       ResourceMark rm;
2969       if (cld->is_anonymous()) {
2970         return;
2971       }
2972       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
2973         for (int i = 0; i < cld->dictionary()->table_size(); ++i) {
2974           Dictionary* curr_dictionary = cld->dictionary();
2975           DictionaryEntry* p = curr_dictionary->bucket(i);
2976           while (p != NULL) {
2977             Symbol* name = p->instance_klass()->name();
2978             unsigned int d_hash = _master_dictionary->compute_hash(name);
2979             int d_index = _master_dictionary->hash_to_index(d_hash);
2980             DictionaryEntry* next = p->next();
2981             if (p->literal()->class_loader_data() != cld) {
2982               // This is an initiating class loader entry; don't use it
2983               log_trace(cds)("Skipping initiating cl entry: %s", name->as_C_string());
2984               curr_dictionary->free_entry(p);
2985             } else {
2986               log_trace(cds)("Moved to boot dictionary: %s", name->as_C_string());
2987               curr_dictionary->unlink_entry(p);
2988               p->set_pd_set(NULL); // pd_set is runtime only information and will be reconstructed.
2989               _master_dictionary->add_entry(d_index, p);
2990             }
2991             p = next;
2992           }
2993           *curr_dictionary->bucket_addr(i) = NULL;
2994         }
2995       }
2996     }
2997 };
2998 
2999 // Combining platform and system loader dictionaries into boot loader dictionary.
3000 // During run time, we only have one shared dictionary.
3001 void SystemDictionary::combine_shared_dictionaries() {
3002   assert(DumpSharedSpaces, "dump time only");
3003   Dictionary* master_dictionary = ClassLoaderData::the_null_class_loader_data()->dictionary();
3004   CombineDictionariesClosure cdc(master_dictionary);
3005   ClassLoaderDataGraph::cld_do(&cdc);
3006 
3007   // These tables are no longer valid or necessary. Keeping them around will
3008   // cause SystemDictionary::verify() to fail. Let's empty them.
3009   _placeholders        = new PlaceholderTable(_placeholder_table_size);
3010   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
3011 
3012   NOT_PRODUCT(SystemDictionary::verify());
3013 }
3014 
3015 void SystemDictionary::initialize_oop_storage() {
3016   _vm_weak_oop_storage =
3017     new OopStorage("VM Weak Oop Handles",
3018                    VMWeakAlloc_lock,
3019                    VMWeakActive_lock);
3020 }
3021 
3022 OopStorage* SystemDictionary::vm_weak_oop_storage() {
3023   assert(_vm_weak_oop_storage != NULL, "Uninitialized");
3024   return _vm_weak_oop_storage;
3025 }
--- EOF ---