1 /*
   2  * Copyright (c) 1997, 2019, 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/classLoaderDataGraph.inline.hpp"
  33 #include "classfile/classLoaderExt.hpp"
  34 #include "classfile/dictionary.hpp"
  35 #include "classfile/javaClasses.inline.hpp"
  36 #include "classfile/klassFactory.hpp"
  37 #include "classfile/loaderConstraints.hpp"
  38 #include "classfile/packageEntry.hpp"
  39 #include "classfile/placeholders.hpp"
  40 #include "classfile/protectionDomainCache.hpp"
  41 #include "classfile/resolutionErrors.hpp"
  42 #include "classfile/stringTable.hpp"
  43 #include "classfile/symbolTable.hpp"
  44 #include "classfile/systemDictionary.hpp"
  45 #include "classfile/vmSymbols.hpp"
  46 #include "code/codeCache.hpp"
  47 #include "compiler/compileBroker.hpp"
  48 #include "gc/shared/gcTraceTime.inline.hpp"
  49 #include "gc/shared/oopStorage.inline.hpp"
  50 #include "gc/shared/oopStorageSet.hpp"
  51 #include "interpreter/bytecodeStream.hpp"
  52 #include "interpreter/interpreter.hpp"
  53 #include "jfr/jfrEvents.hpp"
  54 #include "logging/log.hpp"
  55 #include "logging/logStream.hpp"
  56 #include "memory/filemap.hpp"
  57 #include "memory/heapShared.hpp"
  58 #include "memory/metaspaceClosure.hpp"
  59 #include "memory/oopFactory.hpp"
  60 #include "memory/resourceArea.hpp"
  61 #include "memory/universe.hpp"
  62 #include "oops/access.inline.hpp"
  63 #include "oops/instanceKlass.hpp"
  64 #include "oops/instanceRefKlass.hpp"
  65 #include "oops/klass.inline.hpp"
  66 #include "oops/method.inline.hpp"
  67 #include "oops/methodData.hpp"
  68 #include "oops/objArrayKlass.hpp"
  69 #include "oops/objArrayOop.inline.hpp"
  70 #include "oops/oop.inline.hpp"
  71 #include "oops/symbol.hpp"
  72 #include "oops/typeArrayKlass.hpp"
  73 #include "prims/jvmtiExport.hpp"
  74 #include "prims/methodHandles.hpp"
  75 #include "runtime/arguments.hpp"
  76 #include "runtime/biasedLocking.hpp"
  77 #include "runtime/fieldType.hpp"
  78 #include "runtime/handles.inline.hpp"
  79 #include "runtime/java.hpp"
  80 #include "runtime/javaCalls.hpp"
  81 #include "runtime/mutexLocker.hpp"
  82 #include "runtime/orderAccess.hpp"
  83 #include "runtime/sharedRuntime.hpp"
  84 #include "runtime/signature.hpp"
  85 #include "services/classLoadingService.hpp"
  86 #include "services/diagnosticCommand.hpp"
  87 #include "services/threadService.hpp"
  88 #include "utilities/macros.hpp"
  89 #if INCLUDE_CDS
  90 #include "classfile/systemDictionaryShared.hpp"
  91 #endif
  92 #if INCLUDE_JFR
  93 #include "jfr/jfr.hpp"
  94 #endif
  95 
  96 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  97 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  98 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  99 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
 100 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
 101 
 102 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 103 
 104 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 105                                                           =  { NULL /*, NULL...*/ };
 106 
 107 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 108 
 109 oop         SystemDictionary::_java_system_loader         =  NULL;
 110 oop         SystemDictionary::_java_platform_loader       =  NULL;
 111 
 112 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 113 
 114 // Default ProtectionDomainCacheSize value
 115 
 116 const int defaultProtectionDomainCacheSize = 1009;
 117 
 118 // ----------------------------------------------------------------------------
 119 // Java-level SystemLoader and PlatformLoader
 120 
 121 oop SystemDictionary::java_system_loader() {
 122   return _java_system_loader;
 123 }
 124 
 125 oop SystemDictionary::java_platform_loader() {
 126   return _java_platform_loader;
 127 }
 128 
 129 void SystemDictionary::compute_java_loaders(TRAPS) {
 130   JavaValue result(T_OBJECT);
 131   InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
 132   JavaCalls::call_static(&result,
 133                          class_loader_klass,
 134                          vmSymbols::getSystemClassLoader_name(),
 135                          vmSymbols::void_classloader_signature(),
 136                          CHECK);
 137 
 138   _java_system_loader = (oop)result.get_jobject();
 139 
 140   JavaCalls::call_static(&result,
 141                          class_loader_klass,
 142                          vmSymbols::getPlatformClassLoader_name(),
 143                          vmSymbols::void_classloader_signature(),
 144                          CHECK);
 145 
 146   _java_platform_loader = (oop)result.get_jobject();
 147 }
 148 
 149 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
 150   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 151   return ClassLoaderDataGraph::find_or_create(class_loader);
 152 }
 153 
 154 // ----------------------------------------------------------------------------
 155 // Parallel class loading check
 156 
 157 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 158   if (class_loader.is_null()) return true;
 159   if (AlwaysLockClassLoader) return false;
 160   return java_lang_ClassLoader::parallelCapable(class_loader());
 161 }
 162 // ----------------------------------------------------------------------------
 163 // ParallelDefineClass flag does not apply to bootclass loader
 164 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 165    if (class_loader.is_null()) return false;
 166    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 167      return true;
 168    }
 169    return false;
 170 }
 171 
 172 // Returns true if the passed class loader is the builtin application class loader
 173 // or a custom system class loader. A customer system class loader can be
 174 // specified via -Djava.system.class.loader.
 175 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 176   if (class_loader == NULL) {
 177     return false;
 178   }
 179   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 180          class_loader == _java_system_loader);
 181 }
 182 
 183 // Returns true if the passed class loader is the platform class loader.
 184 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 185   if (class_loader == NULL) {
 186     return false;
 187   }
 188   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 189 }
 190 
 191 // ----------------------------------------------------------------------------
 192 // Resolving of classes
 193 
 194 // Forwards to resolve_or_null
 195 
 196 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 197   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 198   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 199     // can return a null klass
 200     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 201   }
 202   return klass;
 203 }
 204 
 205 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 206                                                      bool throw_error,
 207                                                      Klass* klass, TRAPS) {
 208   if (HAS_PENDING_EXCEPTION) {
 209     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 210     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 211     // and if so convert it to a NoClassDefFoundError
 212     // And chain the original ClassNotFoundException
 213     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 214       ResourceMark rm(THREAD);
 215       assert(klass == NULL, "Should not have result with exception pending");
 216       Handle e(THREAD, PENDING_EXCEPTION);
 217       CLEAR_PENDING_EXCEPTION;
 218       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 219     } else {
 220       return NULL;
 221     }
 222   }
 223   // Class not found, throw appropriate error or exception depending on value of throw_error
 224   if (klass == NULL) {
 225     ResourceMark rm(THREAD);
 226     if (throw_error) {
 227       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 228     } else {
 229       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 230     }
 231   }
 232   return klass;
 233 }
 234 
 235 
 236 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 237                                            bool throw_error, TRAPS)
 238 {
 239   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 240 }
 241 
 242 
 243 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
 244 
 245 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 246   if (FieldType::is_array(class_name)) {
 247     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 248   } else {
 249     return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
 250   }
 251 }
 252 
 253 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
 254 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
 255                                                                        Handle class_loader,
 256                                                                        Handle protection_domain,
 257                                                                        TRAPS) {
 258   assert(class_name != NULL && !FieldType::is_array(class_name), "must be");
 259   if (FieldType::is_obj(class_name)) {
 260     ResourceMark rm(THREAD);
 261     // Ignore wrapping L and ;.
 262     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 263                                                  class_name->utf8_length() - 2);
 264     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 265   } else {
 266     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 267   }
 268 }
 269 
 270 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 271   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 272 }
 273 
 274 // Forwards to resolve_instance_class_or_null
 275 
 276 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 277                                                      Handle class_loader,
 278                                                      Handle protection_domain,
 279                                                      TRAPS) {
 280   assert(FieldType::is_array(class_name), "must be array");
 281   Klass* k = NULL;
 282   FieldArrayInfo fd;
 283   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 284   // of this call
 285   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 286   if (t == T_OBJECT) {
 287     // naked oop "k" is OK here -- we assign back into it
 288     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 289                                                          class_loader,
 290                                                          protection_domain,
 291                                                          CHECK_NULL);
 292     if (k != NULL) {
 293       k = k->array_klass(fd.dimension(), CHECK_NULL);
 294     }
 295   } else {
 296     k = Universe::typeArrayKlassObj(t);
 297     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 298   }
 299   return k;
 300 }
 301 
 302 
 303 // Must be called for any super-class or super-interface resolution
 304 // during class definition to allow class circularity checking
 305 // super-interface callers:
 306 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 307 // super-class callers:
 308 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 309 //   load_shared_class - while loading a class from shared archive
 310 //   resolve_instance_class_or_null:
 311 //     via: handle_parallel_super_load
 312 //      when resolving a class that has an existing placeholder with
 313 //      a saved superclass [i.e. a defineClass is currently in progress]
 314 //      if another thread is trying to resolve the class, it must do
 315 //      super-class checks on its own thread to catch class circularity
 316 // This last call is critical in class circularity checking for cases
 317 // where classloading is delegated to different threads and the
 318 // classloader lock is released.
 319 // Take the case: Base->Super->Base
 320 //   1. If thread T1 tries to do a defineClass of class Base
 321 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 322 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 323 //    so it tries to load Super
 324 //   3. If we load the class internally, or user classloader uses same thread
 325 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 326 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 327 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 328 //      3.4 calls resolve_super_or_fail Base
 329 //      3.5 finds T1,Base -> throws class circularity
 330 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 331 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 332 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 333 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 334 //      4.4 finds T2, Super -> throws class circularity
 335 // Must be called, even if superclass is null, since this is
 336 // where the placeholder entry is created which claims this
 337 // thread is loading this class/classloader.
 338 // Be careful when modifying this code: once you have run
 339 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 340 // you need to find_and_remove it before returning.
 341 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 342 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 343                                                        Symbol* super_name,
 344                                                        Handle class_loader,
 345                                                        Handle protection_domain,
 346                                                        bool is_superclass,
 347                                                        TRAPS) {
 348   assert(!FieldType::is_array(super_name), "invalid super class name");
 349 #if INCLUDE_CDS
 350   if (DumpSharedSpaces) {
 351     // Special processing for handling UNREGISTERED shared classes.
 352     InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 353         super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 354     if (k) {
 355       return k;
 356     }
 357   }
 358 #endif // INCLUDE_CDS
 359 
 360   // Double-check, if child class is already loaded, just return super-class,interface
 361   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 362   // dictionary.
 363   // Make sure there's a placeholder for the *child* before resolving.
 364   // Used as a claim that this thread is currently loading superclass/classloader
 365   // Used here for ClassCircularity checks and also for heap verification
 366   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 367   // Must check ClassCircularity before checking if super class is already loaded.
 368   //
 369   // We might not already have a placeholder if this child_name was
 370   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 371   // the name of the class might not be known until the stream is actually
 372   // parsed.
 373   // Bugs 4643874, 4715493
 374 
 375   ClassLoaderData* loader_data = class_loader_data(class_loader);
 376   Dictionary* dictionary = loader_data->dictionary();
 377   unsigned int d_hash = dictionary->compute_hash(child_name);
 378   unsigned int p_hash = placeholders()->compute_hash(child_name);
 379   int p_index = placeholders()->hash_to_index(p_hash);
 380   // can't throw error holding a lock
 381   bool child_already_loaded = false;
 382   bool throw_circularity_error = false;
 383   {
 384     MutexLocker mu(SystemDictionary_lock, THREAD);
 385     InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
 386     InstanceKlass* quicksuperk;
 387     // to support // loading: if child done loading, just return superclass
 388     // if super_name, & class_loader don't match:
 389     // if initial define, SD update will give LinkageError
 390     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 391     // so we don't throw an exception here.
 392     // see: nsk redefclass014 & java.lang.instrument Instrument032
 393     if ((childk != NULL ) && (is_superclass) &&
 394         ((quicksuperk = childk->java_super()) != NULL) &&
 395          ((quicksuperk->name() == super_name) &&
 396             (quicksuperk->class_loader() == class_loader()))) {
 397            return quicksuperk;
 398     } else {
 399       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 400       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 401           throw_circularity_error = true;
 402       }
 403     }
 404     if (!throw_circularity_error) {
 405       // Be careful not to exit resolve_super
 406       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD);
 407     }
 408   }
 409   if (throw_circularity_error) {
 410       ResourceMark rm(THREAD);
 411       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 412   }
 413 
 414 // java.lang.Object should have been found above
 415   assert(super_name != NULL, "null super class for resolving");
 416   // Resolve the super class or interface, check results on return
 417   InstanceKlass* superk =
 418     SystemDictionary::resolve_instance_class_or_null_helper(super_name,
 419                                                             class_loader,
 420                                                             protection_domain,
 421                                                             THREAD);
 422 
 423   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 424   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 425   // or error. GC used to walk the placeholder table as strong roots.
 426   // The instanceKlass is kept alive because the class loader is on the stack,
 427   // which keeps the loader_data alive, as well as all instanceKlasses in
 428   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 429   {
 430     MutexLocker mu(SystemDictionary_lock, THREAD);
 431     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 432     SystemDictionary_lock->notify_all();
 433   }
 434   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 435     // can null superk
 436     Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
 437     assert(k == NULL || k == superk, "must be");
 438     if (k == NULL) {
 439       superk = NULL;
 440     }
 441   }
 442 
 443   return superk;
 444 }
 445 
 446 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 447                                                   Handle class_loader,
 448                                                   Handle protection_domain,
 449                                                   TRAPS) {
 450   if(!has_checkPackageAccess()) return;
 451 
 452   // Now we have to call back to java to check if the initating class has access
 453   JavaValue result(T_VOID);
 454   LogTarget(Debug, protectiondomain) lt;
 455   if (lt.is_enabled()) {
 456     ResourceMark rm;
 457     // Print out trace information
 458     LogStream ls(lt);
 459     ls.print_cr("Checking package access");
 460     if (class_loader() != NULL) {
 461       ls.print("class loader: ");
 462       class_loader()->print_value_on(&ls);
 463     } else {
 464       ls.print_cr("class loader: NULL");
 465     }
 466     if (protection_domain() != NULL) {
 467       ls.print(" protection domain: ");
 468       protection_domain()->print_value_on(&ls);
 469     } else {
 470       ls.print_cr(" protection domain: NULL");
 471     }
 472     ls.print(" loading: "); klass->print_value_on(&ls);
 473     ls.cr();
 474   }
 475 
 476   // This handle and the class_loader handle passed in keeps this class from
 477   // being unloaded through several GC points.
 478   // The class_loader handle passed in is the initiating loader.
 479   Handle mirror(THREAD, klass->java_mirror());
 480 
 481   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 482   JavaCalls::call_special(&result,
 483                          class_loader,
 484                          system_loader,
 485                          vmSymbols::checkPackageAccess_name(),
 486                          vmSymbols::class_protectiondomain_signature(),
 487                          mirror,
 488                          protection_domain,
 489                          THREAD);
 490 
 491   if (HAS_PENDING_EXCEPTION) {
 492     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 493   } else {
 494    log_debug(protectiondomain)("granted");
 495   }
 496 
 497   if (HAS_PENDING_EXCEPTION) return;
 498 
 499   // If no exception has been thrown, we have validated the protection domain
 500   // Insert the protection domain of the initiating class into the set.
 501   {
 502     ClassLoaderData* loader_data = class_loader_data(class_loader);
 503     Dictionary* dictionary = loader_data->dictionary();
 504 
 505     Symbol*  kn = klass->name();
 506     unsigned int d_hash = dictionary->compute_hash(kn);
 507 
 508     MutexLocker mu(SystemDictionary_lock, THREAD);
 509     int d_index = dictionary->hash_to_index(d_hash);
 510     dictionary->add_protection_domain(d_index, d_hash, klass,
 511                                       protection_domain, THREAD);
 512   }
 513 }
 514 
 515 // We only get here if this thread finds that another thread
 516 // has already claimed the placeholder token for the current operation,
 517 // but that other thread either never owned or gave up the
 518 // object lock
 519 // Waits on SystemDictionary_lock to indicate placeholder table updated
 520 // On return, caller must recheck placeholder table state
 521 //
 522 // We only get here if
 523 //  1) custom classLoader, i.e. not bootstrap classloader
 524 //  2) custom classLoader has broken the class loader objectLock
 525 //     so another thread got here in parallel
 526 //
 527 // lockObject must be held.
 528 // Complicated dance due to lock ordering:
 529 // Must first release the classloader object lock to
 530 // allow initial definer to complete the class definition
 531 // and to avoid deadlock
 532 // Reclaim classloader lock object with same original recursion count
 533 // Must release SystemDictionary_lock after notify, since
 534 // class loader lock must be claimed before SystemDictionary_lock
 535 // to prevent deadlocks
 536 //
 537 // The notify allows applications that did an untimed wait() on
 538 // the classloader object lock to not hang.
 539 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 540   assert_lock_strong(SystemDictionary_lock);
 541 
 542   bool calledholdinglock
 543       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 544   assert(calledholdinglock,"must hold lock for notify");
 545   assert((lockObject() != _system_loader_lock_obj && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 546   ObjectSynchronizer::notifyall(lockObject, THREAD);
 547   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 548   SystemDictionary_lock->wait();
 549   SystemDictionary_lock->unlock();
 550   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 551   SystemDictionary_lock->lock();
 552 }
 553 
 554 // If the class in is in the placeholder table, class loading is in progress
 555 // For cases where the application changes threads to load classes, it
 556 // is critical to ClassCircularity detection that we try loading
 557 // the superclass on the same thread internally, so we do parallel
 558 // super class loading here.
 559 // This also is critical in cases where the original thread gets stalled
 560 // even in non-circularity situations.
 561 // Note: must call resolve_super_or_fail even if null super -
 562 // to force placeholder entry creation for this class for circularity detection
 563 // Caller must check for pending exception
 564 // Returns non-null Klass* if other thread has completed load
 565 // and we are done,
 566 // If return null Klass* and no pending exception, the caller must load the class
 567 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 568     Symbol* name, Symbol* superclassname, Handle class_loader,
 569     Handle protection_domain, Handle lockObject, TRAPS) {
 570 
 571   ClassLoaderData* loader_data = class_loader_data(class_loader);
 572   Dictionary* dictionary = loader_data->dictionary();
 573   unsigned int d_hash = dictionary->compute_hash(name);
 574   unsigned int p_hash = placeholders()->compute_hash(name);
 575   int p_index = placeholders()->hash_to_index(p_hash);
 576 
 577   // superk is not used, resolve_super called for circularity check only
 578   // This code is reached in two situations. One if this thread
 579   // is loading the same class twice (e.g. ClassCircularity, or
 580   // java.lang.instrument).
 581   // The second is if another thread started the resolve_super first
 582   // and has not yet finished.
 583   // In both cases the original caller will clean up the placeholder
 584   // entry on error.
 585   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 586                                                           superclassname,
 587                                                           class_loader,
 588                                                           protection_domain,
 589                                                           true,
 590                                                           CHECK_NULL);
 591 
 592   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 593   // Serial class loaders and bootstrap classloader do wait for superclass loads
 594  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 595     MutexLocker mu(SystemDictionary_lock, THREAD);
 596     // Check if classloading completed while we were loading superclass or waiting
 597     return find_class(d_hash, name, dictionary);
 598   }
 599 
 600   // must loop to both handle other placeholder updates
 601   // and spurious notifications
 602   bool super_load_in_progress = true;
 603   PlaceholderEntry* placeholder;
 604   while (super_load_in_progress) {
 605     MutexLocker mu(SystemDictionary_lock, THREAD);
 606     // Check if classloading completed while we were loading superclass or waiting
 607     InstanceKlass* check = find_class(d_hash, name, dictionary);
 608     if (check != NULL) {
 609       // Klass is already loaded, so just return it
 610       return check;
 611     } else {
 612       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 613       if (placeholder && placeholder->super_load_in_progress() ){
 614         // We only get here if the application has released the
 615         // classloader lock when another thread was in the middle of loading a
 616         // superclass/superinterface for this class, and now
 617         // this thread is also trying to load this class.
 618         // To minimize surprises, the first thread that started to
 619         // load a class should be the one to complete the loading
 620         // with the classfile it initially expected.
 621         // This logic has the current thread wait once it has done
 622         // all the superclass/superinterface loading it can, until
 623         // the original thread completes the class loading or fails
 624         // If it completes we will use the resulting InstanceKlass
 625         // which we will find below in the systemDictionary.
 626         // We also get here for parallel bootstrap classloader
 627         if (class_loader.is_null()) {
 628           SystemDictionary_lock->wait();
 629         } else {
 630           double_lock_wait(lockObject, THREAD);
 631         }
 632       } else {
 633         // If not in SD and not in PH, other thread's load must have failed
 634         super_load_in_progress = false;
 635       }
 636     }
 637   }
 638   return NULL;
 639 }
 640 
 641 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
 642   assert(event != NULL, "invariant");
 643   assert(k != NULL, "invariant");
 644   assert(event->should_commit(), "invariant");
 645   event->set_loadedClass(k);
 646   event->set_definingClassLoader(k->class_loader_data());
 647   event->set_initiatingClassLoader(init_cld);
 648   event->commit();
 649 }
 650 
 651 
 652 // Be careful when modifying this code: once you have run
 653 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 654 // you need to find_and_remove it before returning.
 655 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 656 //
 657 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
 658 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 659                                                                 Handle class_loader,
 660                                                                 Handle protection_domain,
 661                                                                 TRAPS) {
 662   assert(name != NULL && !FieldType::is_array(name) &&
 663          !FieldType::is_obj(name), "invalid class name");
 664 
 665   EventClassLoad class_load_start_event;
 666 
 667   HandleMark hm(THREAD);
 668 
 669   // Fix for 4474172; see evaluation for more details
 670   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 671   ClassLoaderData* loader_data = register_loader(class_loader);
 672   Dictionary* dictionary = loader_data->dictionary();
 673   unsigned int d_hash = dictionary->compute_hash(name);
 674 
 675   // Do lookup to see if class already exist and the protection domain
 676   // has the right access
 677   // This call uses find which checks protection domain already matches
 678   // All subsequent calls use find_class, and set has_loaded_class so that
 679   // before we return a result we call out to java to check for valid protection domain
 680   // to allow returning the Klass* and add it to the pd_set if it is valid
 681   {
 682     InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
 683     if (probe != NULL) return probe;
 684   }
 685 
 686   // Non-bootstrap class loaders will call out to class loader and
 687   // define via jvm/jni_DefineClass which will acquire the
 688   // class loader object lock to protect against multiple threads
 689   // defining the class in parallel by accident.
 690   // This lock must be acquired here so the waiter will find
 691   // any successful result in the SystemDictionary and not attempt
 692   // the define.
 693   // ParallelCapable Classloaders and the bootstrap classloader
 694   // do not acquire lock here.
 695   bool DoObjectLock = true;
 696   if (is_parallelCapable(class_loader)) {
 697     DoObjectLock = false;
 698   }
 699 
 700   unsigned int p_hash = placeholders()->compute_hash(name);
 701   int p_index = placeholders()->hash_to_index(p_hash);
 702 
 703   // Class is not in SystemDictionary so we have to do loading.
 704   // Make sure we are synchronized on the class loader before we proceed
 705   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 706   check_loader_lock_contention(lockObject, THREAD);
 707   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 708 
 709   // Check again (after locking) if class already exist in SystemDictionary
 710   bool class_has_been_loaded   = false;
 711   bool super_load_in_progress  = false;
 712   bool havesupername = false;
 713   InstanceKlass* k = NULL;
 714   PlaceholderEntry* placeholder;
 715   Symbol* superclassname = NULL;
 716 
 717   assert(THREAD->can_call_java(),
 718          "can not load classes with compiler thread: class=%s, classloader=%s",
 719          name->as_C_string(),
 720          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 721   {
 722     MutexLocker mu(SystemDictionary_lock, THREAD);
 723     InstanceKlass* check = find_class(d_hash, name, dictionary);
 724     if (check != NULL) {
 725       // InstanceKlass is already loaded, so just return it
 726       class_has_been_loaded = true;
 727       k = check;
 728     } else {
 729       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 730       if (placeholder && placeholder->super_load_in_progress()) {
 731          super_load_in_progress = true;
 732          if (placeholder->havesupername() == true) {
 733            superclassname = placeholder->supername();
 734            havesupername = true;
 735          }
 736       }
 737     }
 738   }
 739 
 740   // If the class is in the placeholder table, class loading is in progress
 741   if (super_load_in_progress && havesupername==true) {
 742     k = handle_parallel_super_load(name,
 743                                    superclassname,
 744                                    class_loader,
 745                                    protection_domain,
 746                                    lockObject, THREAD);
 747     if (HAS_PENDING_EXCEPTION) {
 748       return NULL;
 749     }
 750     if (k != NULL) {
 751       class_has_been_loaded = true;
 752     }
 753   }
 754 
 755   bool throw_circularity_error = false;
 756   if (!class_has_been_loaded) {
 757     bool load_instance_added = false;
 758 
 759     // add placeholder entry to record loading instance class
 760     // Five cases:
 761     // All cases need to prevent modifying bootclasssearchpath
 762     // in parallel with a classload of same classname
 763     // Redefineclasses uses existence of the placeholder for the duration
 764     // of the class load to prevent concurrent redefinition of not completely
 765     // defined classes.
 766     // case 1. traditional classloaders that rely on the classloader object lock
 767     //   - no other need for LOAD_INSTANCE
 768     // case 2. traditional classloaders that break the classloader object lock
 769     //    as a deadlock workaround. Detection of this case requires that
 770     //    this check is done while holding the classloader object lock,
 771     //    and that lock is still held when calling classloader's loadClass.
 772     //    For these classloaders, we ensure that the first requestor
 773     //    completes the load and other requestors wait for completion.
 774     // case 3. Bootstrap classloader - don't own objectLocker
 775     //    This classloader supports parallelism at the classloader level,
 776     //    but only allows a single load of a class/classloader pair.
 777     //    No performance benefit and no deadlock issues.
 778     // case 4. parallelCapable user level classloaders - without objectLocker
 779     //    Allow parallel classloading of a class/classloader pair
 780 
 781     {
 782       MutexLocker mu(SystemDictionary_lock, THREAD);
 783       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 784         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 785         if (oldprobe) {
 786           // only need check_seen_thread once, not on each loop
 787           // 6341374 java/lang/Instrument with -Xcomp
 788           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 789             throw_circularity_error = true;
 790           } else {
 791             // case 1: traditional: should never see load_in_progress.
 792             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 793 
 794               // case 3: bootstrap classloader: prevent futile classloading,
 795               // wait on first requestor
 796               if (class_loader.is_null()) {
 797                 SystemDictionary_lock->wait();
 798               } else {
 799               // case 2: traditional with broken classloader lock. wait on first
 800               // requestor.
 801                 double_lock_wait(lockObject, THREAD);
 802               }
 803               // Check if classloading completed while we were waiting
 804               InstanceKlass* check = find_class(d_hash, name, dictionary);
 805               if (check != NULL) {
 806                 // Klass is already loaded, so just return it
 807                 k = check;
 808                 class_has_been_loaded = true;
 809               }
 810               // check if other thread failed to load and cleaned up
 811               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 812             }
 813           }
 814         }
 815       }
 816       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 817       // case 4: parallelCapable: allow competing threads to try
 818       // LOAD_INSTANCE in parallel
 819 
 820       if (!throw_circularity_error && !class_has_been_loaded) {
 821         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 822         load_instance_added = true;
 823         // For class loaders that do not acquire the classloader object lock,
 824         // if they did not catch another thread holding LOAD_INSTANCE,
 825         // need a check analogous to the acquire ObjectLocker/find_class
 826         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 827         // one final check if the load has already completed
 828         // class loaders holding the ObjectLock shouldn't find the class here
 829         InstanceKlass* check = find_class(d_hash, name, dictionary);
 830         if (check != NULL) {
 831         // Klass is already loaded, so return it after checking/adding protection domain
 832           k = check;
 833           class_has_been_loaded = true;
 834         }
 835       }
 836     }
 837 
 838     // must throw error outside of owning lock
 839     if (throw_circularity_error) {
 840       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 841       ResourceMark rm(THREAD);
 842       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 843     }
 844 
 845     if (!class_has_been_loaded) {
 846 
 847       // Do actual loading
 848       k = load_instance_class(name, class_loader, THREAD);
 849 
 850       // If everything was OK (no exceptions, no null return value), and
 851       // class_loader is NOT the defining loader, do a little more bookkeeping.
 852       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 853         k->class_loader() != class_loader()) {
 854 
 855         check_constraints(d_hash, k, class_loader, false, THREAD);
 856 
 857         // Need to check for a PENDING_EXCEPTION again; check_constraints
 858         // can throw but we may have to remove entry from the placeholder table below.
 859         if (!HAS_PENDING_EXCEPTION) {
 860           // Record dependency for non-parent delegation.
 861           // This recording keeps the defining class loader of the klass (k) found
 862           // from being unloaded while the initiating class loader is loaded
 863           // even if the reference to the defining class loader is dropped
 864           // before references to the initiating class loader.
 865           loader_data->record_dependency(k);
 866 
 867           { // Grabbing the Compile_lock prevents systemDictionary updates
 868             // during compilations.
 869             MutexLocker mu(Compile_lock, THREAD);
 870             update_dictionary(d_hash, p_index, p_hash,
 871               k, class_loader, THREAD);
 872           }
 873 
 874           if (JvmtiExport::should_post_class_load()) {
 875             Thread *thread = THREAD;
 876             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 877             JvmtiExport::post_class_load((JavaThread *) thread, k);
 878           }
 879         }
 880       }
 881     } // load_instance_class
 882 
 883     if (load_instance_added == true) {
 884       // clean up placeholder entries for LOAD_INSTANCE success or error
 885       // This brackets the SystemDictionary updates for both defining
 886       // and initiating loaders
 887       MutexLocker mu(SystemDictionary_lock, THREAD);
 888       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 889       SystemDictionary_lock->notify_all();
 890     }
 891   }
 892 
 893   if (HAS_PENDING_EXCEPTION || k == NULL) {
 894     return NULL;
 895   }
 896   if (class_load_start_event.should_commit()) {
 897     post_class_load_event(&class_load_start_event, k, loader_data);
 898   }
 899 #ifdef ASSERT
 900   {
 901     ClassLoaderData* loader_data = k->class_loader_data();
 902     MutexLocker mu(SystemDictionary_lock, THREAD);
 903     InstanceKlass* kk = find_class(name, loader_data);
 904     assert(kk == k, "should be present in dictionary");
 905   }
 906 #endif
 907 
 908   // return if the protection domain in NULL
 909   if (protection_domain() == NULL) return k;
 910 
 911   // Check the protection domain has the right access
 912   if (dictionary->is_valid_protection_domain(d_hash, name,
 913                                              protection_domain)) {
 914     return k;
 915   }
 916 
 917   // Verify protection domain. If it fails an exception is thrown
 918   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 919 
 920   return k;
 921 }
 922 
 923 
 924 // This routine does not lock the system dictionary.
 925 //
 926 // Since readers don't hold a lock, we must make sure that system
 927 // dictionary entries are only removed at a safepoint (when only one
 928 // thread is running), and are added to in a safe way (all links must
 929 // be updated in an MT-safe manner).
 930 //
 931 // Callers should be aware that an entry could be added just after
 932 // _dictionary->bucket(index) is read here, so the caller will not see
 933 // the new entry.
 934 
 935 Klass* SystemDictionary::find(Symbol* class_name,
 936                               Handle class_loader,
 937                               Handle protection_domain,
 938                               TRAPS) {
 939 
 940   // The result of this call should be consistent with the result
 941   // of the call to resolve_instance_class_or_null().
 942   // See evaluation 6790209 and 4474172 for more details.
 943   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 944   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 945 
 946   if (loader_data == NULL) {
 947     // If the ClassLoaderData has not been setup,
 948     // then the class loader has no entries in the dictionary.
 949     return NULL;
 950   }
 951 
 952   Dictionary* dictionary = loader_data->dictionary();
 953   unsigned int d_hash = dictionary->compute_hash(class_name);
 954   return dictionary->find(d_hash, class_name,
 955                           protection_domain);
 956 }
 957 
 958 
 959 // Look for a loaded instance or array klass by name.  Do not do any loading.
 960 // return NULL in case of error.
 961 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 962                                                       Handle class_loader,
 963                                                       Handle protection_domain,
 964                                                       TRAPS) {
 965   Klass* k = NULL;
 966   assert(class_name != NULL, "class name must be non NULL");
 967 
 968   if (FieldType::is_array(class_name)) {
 969     // The name refers to an array.  Parse the name.
 970     // dimension and object_key in FieldArrayInfo are assigned as a
 971     // side-effect of this call
 972     FieldArrayInfo fd;
 973     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 974     if (t != T_OBJECT) {
 975       k = Universe::typeArrayKlassObj(t);
 976     } else {
 977       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 978     }
 979     if (k != NULL) {
 980       k = k->array_klass_or_null(fd.dimension());
 981     }
 982   } else {
 983     k = find(class_name, class_loader, protection_domain, THREAD);
 984   }
 985   return k;
 986 }
 987 
 988 // Note: this method is much like resolve_from_stream, but
 989 // does not publish the classes via the SystemDictionary.
 990 // Handles unsafe_DefineAnonymousClass and redefineclasses
 991 // RedefinedClasses do not add to the class hierarchy
 992 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
 993                                               Handle class_loader,
 994                                               Handle protection_domain,
 995                                               ClassFileStream* st,
 996                                               const InstanceKlass* unsafe_anonymous_host,
 997                                               GrowableArray<Handle>* cp_patches,
 998                                               TRAPS) {
 999 
1000   EventClassLoad class_load_start_event;
1001 
1002   ClassLoaderData* loader_data;
1003   if (unsafe_anonymous_host != NULL) {
1004     // Create a new CLD for an unsafe anonymous class, that uses the same class loader
1005     // as the unsafe_anonymous_host
1006     guarantee(unsafe_anonymous_host->class_loader() == class_loader(), "should be the same");
1007     loader_data = ClassLoaderData::unsafe_anonymous_class_loader_data(class_loader);
1008   } else {
1009     loader_data = ClassLoaderData::class_loader_data(class_loader());
1010   }
1011 
1012   assert(st != NULL, "invariant");
1013   assert(st->need_verify(), "invariant");
1014 
1015   // Parse stream and create a klass.
1016   // Note that we do this even though this klass might
1017   // already be present in the SystemDictionary, otherwise we would not
1018   // throw potential ClassFormatErrors.
1019 
1020   InstanceKlass* k = KlassFactory::create_from_stream(st,
1021                                                       class_name,
1022                                                       loader_data,
1023                                                       protection_domain,
1024                                                       unsafe_anonymous_host,
1025                                                       cp_patches,
1026                                                       CHECK_NULL);
1027 
1028   if (unsafe_anonymous_host != NULL && k != NULL) {
1029     // Unsafe anonymous classes must update ClassLoaderData holder (was unsafe_anonymous_host loader)
1030     // so that they can be unloaded when the mirror is no longer referenced.
1031     k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
1032 
1033     {
1034       MutexLocker mu_r(Compile_lock, THREAD);
1035 
1036       // Add to class hierarchy, initialize vtables, and do possible
1037       // deoptimizations.
1038       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1039       // But, do not add to dictionary.
1040     }
1041 
1042     // Rewrite and patch constant pool here.
1043     k->link_class(CHECK_NULL);
1044     if (cp_patches != NULL) {
1045       k->constants()->patch_resolved_references(cp_patches);
1046     }
1047 
1048     // If it's anonymous, initialize it now, since nobody else will.
1049     k->eager_initialize(CHECK_NULL);
1050 
1051     // notify jvmti
1052     if (JvmtiExport::should_post_class_load()) {
1053         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1054         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1055     }
1056     if (class_load_start_event.should_commit()) {
1057       post_class_load_event(&class_load_start_event, k, loader_data);
1058     }
1059   }
1060   assert(unsafe_anonymous_host != NULL || NULL == cp_patches,
1061          "cp_patches only found with unsafe_anonymous_host");
1062 
1063   return k;
1064 }
1065 
1066 // Add a klass to the system from a stream (called by jni_DefineClass and
1067 // JVM_DefineClass).
1068 // Note: class_name can be NULL. In that case we do not know the name of
1069 // the class until we have parsed the stream.
1070 
1071 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1072                                                      Handle class_loader,
1073                                                      Handle protection_domain,
1074                                                      ClassFileStream* st,
1075                                                      TRAPS) {
1076 
1077   HandleMark hm(THREAD);
1078 
1079   // Classloaders that support parallelism, e.g. bootstrap classloader,
1080   // do not acquire lock here
1081   bool DoObjectLock = true;
1082   if (is_parallelCapable(class_loader)) {
1083     DoObjectLock = false;
1084   }
1085 
1086   ClassLoaderData* loader_data = register_loader(class_loader);
1087 
1088   // Make sure we are synchronized on the class loader before we proceed
1089   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1090   check_loader_lock_contention(lockObject, THREAD);
1091   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1092 
1093   assert(st != NULL, "invariant");
1094 
1095   // Parse the stream and create a klass.
1096   // Note that we do this even though this klass might
1097   // already be present in the SystemDictionary, otherwise we would not
1098   // throw potential ClassFormatErrors.
1099  InstanceKlass* k = NULL;
1100 
1101 #if INCLUDE_CDS
1102   if (!DumpSharedSpaces) {
1103     k = SystemDictionaryShared::lookup_from_stream(class_name,
1104                                                    class_loader,
1105                                                    protection_domain,
1106                                                    st,
1107                                                    CHECK_NULL);
1108   }
1109 #endif
1110 
1111   if (k == NULL) {
1112     if (st->buffer() == NULL) {
1113       return NULL;
1114     }
1115     k = KlassFactory::create_from_stream(st,
1116                                          class_name,
1117                                          loader_data,
1118                                          protection_domain,
1119                                          NULL, // unsafe_anonymous_host
1120                                          NULL, // cp_patches
1121                                          CHECK_NULL);
1122   }
1123 
1124   assert(k != NULL, "no klass created");
1125   Symbol* h_name = k->name();
1126   assert(class_name == NULL || class_name == h_name, "name mismatch");
1127 
1128   // Add class just loaded
1129   // If a class loader supports parallel classloading handle parallel define requests
1130   // find_or_define_instance_class may return a different InstanceKlass
1131   if (is_parallelCapable(class_loader)) {
1132     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1133     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1134       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1135       assert(defined_k != NULL, "Should have a klass if there's no exception");
1136       loader_data->add_to_deallocate_list(k);
1137       k = defined_k;
1138     }
1139   } else {
1140     define_instance_class(k, THREAD);
1141   }
1142 
1143   // If defining the class throws an exception register 'k' for cleanup.
1144   if (HAS_PENDING_EXCEPTION) {
1145     assert(k != NULL, "Must have an instance klass here!");
1146     loader_data->add_to_deallocate_list(k);
1147     return NULL;
1148   }
1149 
1150   // Make sure we have an entry in the SystemDictionary on success
1151   debug_only( {
1152     MutexLocker mu(SystemDictionary_lock, THREAD);
1153 
1154     Klass* check = find_class(h_name, k->class_loader_data());
1155     assert(check == k, "should be present in the dictionary");
1156   } );
1157 
1158   return k;
1159 }
1160 
1161 #if INCLUDE_CDS
1162 // Load a class for boot loader from the shared spaces. This also
1163 // forces the super class and all interfaces to be loaded.
1164 InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
1165                                                         TRAPS) {
1166   InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1167   if (ik != NULL && ik->is_shared_boot_class()) {
1168     return load_shared_class(ik, Handle(), Handle(), NULL, THREAD);
1169   }
1170   return NULL;
1171 }
1172 
1173 // Check if a shared class can be loaded by the specific classloader:
1174 //
1175 // NULL classloader:
1176 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1177 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1178 //     be defined in an unnamed module.
1179 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1180                                                InstanceKlass* ik,
1181                                                Handle class_loader, TRAPS) {
1182   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1183          "Cannot use sharing if java.base is patched");
1184   ResourceMark rm;
1185   int path_index = ik->shared_classpath_index();
1186   ClassLoaderData* loader_data = class_loader_data(class_loader);
1187   if (path_index < 0) {
1188     // path_index < 0 indicates that the class is intended for a custom loader
1189     // and should not be loaded by boot/platform/app loaders
1190     if (loader_data->is_builtin_class_loader_data()) {
1191       return false;
1192     } else {
1193       return true;
1194     }
1195   }
1196   SharedClassPathEntry* ent =
1197             (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1198   if (!Universe::is_module_initialized()) {
1199     assert(ent != NULL && ent->is_modules_image(),
1200            "Loading non-bootstrap classes before the module system is initialized");
1201     assert(class_loader.is_null(), "sanity");
1202     return true;
1203   }
1204   // Get the pkg_entry from the classloader
1205   TempNewSymbol pkg_name = NULL;
1206   PackageEntry* pkg_entry = NULL;
1207   ModuleEntry* mod_entry = NULL;
1208   const char* pkg_string = NULL;
1209   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1210   if (pkg_name != NULL) {
1211     pkg_string = pkg_name->as_C_string();
1212     if (loader_data != NULL) {
1213       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1214     }
1215     if (pkg_entry != NULL) {
1216       mod_entry = pkg_entry->module();
1217     }
1218   }
1219 
1220   // If the archived class is from a module that has been patched at runtime,
1221   // the class cannot be loaded from the archive.
1222   if (mod_entry != NULL && mod_entry->is_patched()) {
1223     return false;
1224   }
1225 
1226   if (class_loader.is_null()) {
1227     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1228     // The NULL classloader can load archived class originated from the
1229     // "modules" jimage and the -Xbootclasspath/a. For class from the
1230     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1231     // by the NULL classloader.
1232     if (mod_entry != NULL) {
1233       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1234       // ModuleEntry's location agrees with the archived class' origination.
1235       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1236         return true; // Module class from the "module" jimage
1237       }
1238     }
1239 
1240     // If the archived class is not from the "module" jimage, the class can be
1241     // loaded by the NULL classloader if
1242     //
1243     // 1. the class is from the unamed package
1244     // 2. or, the class is not from a module defined in the NULL classloader
1245     // 3. or, the class is from an unamed module
1246     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1247       // the class is from the -Xbootclasspath/a
1248       if (pkg_string == NULL ||
1249           pkg_entry == NULL ||
1250           pkg_entry->in_unnamed_module()) {
1251         assert(mod_entry == NULL ||
1252                mod_entry == loader_data->unnamed_module(),
1253                "the unnamed module is not defined in the classloader");
1254         return true;
1255       }
1256     }
1257     return false;
1258   } else {
1259     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1260               ik, class_loader, pkg_string, pkg_name,
1261               pkg_entry, mod_entry, CHECK_(false));
1262     return res;
1263   }
1264 }
1265 
1266 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1267                                                    Handle class_loader,
1268                                                    Handle protection_domain,
1269                                                    const ClassFileStream *cfs,
1270                                                    TRAPS) {
1271   assert(ik != NULL, "sanity");
1272   assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
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<InstanceKlass*>* interfaces = ik->local_interfaces();
1302   int num_interfaces = interfaces->length();
1303   for (int index = 0; index < num_interfaces; index++) {
1304     InstanceKlass* 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, cfs, 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   ik->set_has_passed_fingerprint_check(false);
1369   if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1370     uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1371     uint64_t cds_fp = ik->get_stored_fingerprint();
1372     if (aot_fp != 0 && aot_fp == cds_fp) {
1373       // This class matches with a class saved in an AOT library
1374       ik->set_has_passed_fingerprint_check(true);
1375     } else {
1376       ResourceMark rm;
1377       log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1378     }
1379   }
1380 
1381   return ik;
1382 }
1383 #endif // INCLUDE_CDS
1384 
1385 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1386 
1387   if (class_loader.is_null()) {
1388     ResourceMark rm;
1389     PackageEntry* pkg_entry = NULL;
1390     bool search_only_bootloader_append = false;
1391     ClassLoaderData *loader_data = class_loader_data(class_loader);
1392 
1393     // Find the package in the boot loader's package entry table.
1394     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1395     if (pkg_name != NULL) {
1396       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1397     }
1398 
1399     // Prior to attempting to load the class, enforce the boot loader's
1400     // visibility boundaries.
1401     if (!Universe::is_module_initialized()) {
1402       // During bootstrapping, prior to module initialization, any
1403       // class attempting to be loaded must be checked against the
1404       // java.base packages in the boot loader's PackageEntryTable.
1405       // No class outside of java.base is allowed to be loaded during
1406       // this bootstrapping window.
1407       if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1408         // Class is either in the unnamed package or in
1409         // a named package within the unnamed module.  Either
1410         // case is outside of java.base, do not attempt to
1411         // load the class post java.base definition.  If
1412         // java.base has not been defined, let the class load
1413         // and its package will be checked later by
1414         // ModuleEntryTable::verify_javabase_packages.
1415         if (ModuleEntryTable::javabase_defined()) {
1416           return NULL;
1417         }
1418       } else {
1419         // Check that the class' package is defined within java.base.
1420         ModuleEntry* mod_entry = pkg_entry->module();
1421         Symbol* mod_entry_name = mod_entry->name();
1422         if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1423           return NULL;
1424         }
1425       }
1426     } else {
1427       // After the module system has been initialized, check if the class'
1428       // package is in a module defined to the boot loader.
1429       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1430         // Class is either in the unnamed package, in a named package
1431         // within a module not defined to the boot loader or in a
1432         // a named package within the unnamed module.  In all cases,
1433         // limit visibility to search for the class only in the boot
1434         // loader's append path.
1435         if (!ClassLoader::has_bootclasspath_append()) {
1436            // If there is no bootclasspath append entry, no need to continue
1437            // searching.
1438            return NULL;
1439         }
1440         search_only_bootloader_append = true;
1441       }
1442     }
1443 
1444     // Prior to bootstrapping's module initialization, never load a class outside
1445     // of the boot loader's module path
1446     assert(Universe::is_module_initialized() ||
1447            !search_only_bootloader_append,
1448            "Attempt to load a class outside of boot loader's module path");
1449 
1450     // Search for classes in the CDS archive.
1451     InstanceKlass* k = NULL;
1452     {
1453 #if INCLUDE_CDS
1454       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1455       k = load_shared_boot_class(class_name, THREAD);
1456 #endif
1457     }
1458 
1459     if (k == NULL) {
1460       // Use VM class loader
1461       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1462       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1463     }
1464 
1465     // find_or_define_instance_class may return a different InstanceKlass
1466     if (k != NULL) {
1467       InstanceKlass* defined_k =
1468         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1469       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1470         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1471         assert(defined_k != NULL, "Should have a klass if there's no exception");
1472         loader_data->add_to_deallocate_list(k);
1473         k = defined_k;
1474       } else if (HAS_PENDING_EXCEPTION) {
1475         loader_data->add_to_deallocate_list(k);
1476         return NULL;
1477       }
1478     }
1479     return k;
1480   } else {
1481     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1482     ResourceMark rm(THREAD);
1483 
1484     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1485     JavaThread* jt = (JavaThread*) THREAD;
1486 
1487     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1488                                ClassLoader::perf_app_classload_selftime(),
1489                                ClassLoader::perf_app_classload_count(),
1490                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1491                                jt->get_thread_stat()->perf_timers_addr(),
1492                                PerfClassTraceTime::CLASS_LOAD);
1493 
1494     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1495     // Translate to external class name format, i.e., convert '/' chars to '.'
1496     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1497 
1498     JavaValue result(T_OBJECT);
1499 
1500     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1501 
1502     // Call public unsynchronized loadClass(String) directly for all class loaders.
1503     // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1504     // acquire a class-name based lock rather than the class loader object lock.
1505     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1506     JavaCalls::call_virtual(&result,
1507                             class_loader,
1508                             spec_klass,
1509                             vmSymbols::loadClass_name(),
1510                             vmSymbols::string_class_signature(),
1511                             string,
1512                             CHECK_NULL);
1513 
1514     assert(result.get_type() == T_OBJECT, "just checking");
1515     oop obj = (oop) result.get_jobject();
1516 
1517     // Primitive classes return null since forName() can not be
1518     // used to obtain any of the Class objects representing primitives or void
1519     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1520       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1521       // For user defined Java class loaders, check that the name returned is
1522       // the same as that requested.  This check is done for the bootstrap
1523       // loader when parsing the class file.
1524       if (class_name == k->name()) {
1525         return k;
1526       }
1527     }
1528     // Class is not found or has the wrong name, return NULL
1529     return NULL;
1530   }
1531 }
1532 
1533 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1534   EventClassDefine event;
1535   if (event.should_commit()) {
1536     event.set_definedClass(k);
1537     event.set_definingClassLoader(def_cld);
1538     event.commit();
1539   }
1540 }
1541 
1542 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1543 
1544   HandleMark hm(THREAD);
1545   ClassLoaderData* loader_data = k->class_loader_data();
1546   Handle class_loader_h(THREAD, loader_data->class_loader());
1547 
1548  // for bootstrap and other parallel classloaders don't acquire lock,
1549  // use placeholder token
1550  // If a parallelCapable class loader calls define_instance_class instead of
1551  // find_or_define_instance_class to get here, we have a timing
1552  // hole with systemDictionary updates and check_constraints
1553  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1554     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1555          compute_loader_lock_object(class_loader_h, THREAD)),
1556          "define called without lock");
1557   }
1558 
1559   // Check class-loading constraints. Throw exception if violation is detected.
1560   // Grabs and releases SystemDictionary_lock
1561   // The check_constraints/find_class call and update_dictionary sequence
1562   // must be "atomic" for a specific class/classloader pair so we never
1563   // define two different instanceKlasses for that class/classloader pair.
1564   // Existing classloaders will call define_instance_class with the
1565   // classloader lock held
1566   // Parallel classloaders will call find_or_define_instance_class
1567   // which will require a token to perform the define class
1568   Symbol*  name_h = k->name();
1569   Dictionary* dictionary = loader_data->dictionary();
1570   unsigned int d_hash = dictionary->compute_hash(name_h);
1571   check_constraints(d_hash, k, class_loader_h, true, CHECK);
1572 
1573   // Register class just loaded with class loader (placed in Vector)
1574   // Note we do this before updating the dictionary, as this can
1575   // fail with an OutOfMemoryError (if it does, we will *not* put this
1576   // class in the dictionary and will not update the class hierarchy).
1577   // JVMTI FollowReferences needs to find the classes this way.
1578   if (k->class_loader() != NULL) {
1579     methodHandle m(THREAD, Universe::loader_addClass_method());
1580     JavaValue result(T_VOID);
1581     JavaCallArguments args(class_loader_h);
1582     args.push_oop(Handle(THREAD, k->java_mirror()));
1583     JavaCalls::call(&result, m, &args, CHECK);
1584   }
1585 
1586   // Add the new class. We need recompile lock during update of CHA.
1587   {
1588     unsigned int p_hash = placeholders()->compute_hash(name_h);
1589     int p_index = placeholders()->hash_to_index(p_hash);
1590 
1591     MutexLocker mu_r(Compile_lock, THREAD);
1592 
1593     // Add to class hierarchy, initialize vtables, and do possible
1594     // deoptimizations.
1595     add_to_hierarchy(k, CHECK); // No exception, but can block
1596 
1597     // Add to systemDictionary - so other classes can see it.
1598     // Grabs and releases SystemDictionary_lock
1599     update_dictionary(d_hash, p_index, p_hash,
1600                       k, class_loader_h, THREAD);
1601   }
1602   k->eager_initialize(THREAD);
1603 
1604   // notify jvmti
1605   if (JvmtiExport::should_post_class_load()) {
1606       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1607       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1608 
1609   }
1610   post_class_define_event(k, loader_data);
1611 }
1612 
1613 // Support parallel classloading
1614 // All parallel class loaders, including bootstrap classloader
1615 // lock a placeholder entry for this class/class_loader pair
1616 // to allow parallel defines of different classes for this class loader
1617 // With AllowParallelDefine flag==true, in case they do not synchronize around
1618 // FindLoadedClass/DefineClass, calls, we check for parallel
1619 // loading for them, wait if a defineClass is in progress
1620 // and return the initial requestor's results
1621 // This flag does not apply to the bootstrap classloader.
1622 // With AllowParallelDefine flag==false, call through to define_instance_class
1623 // which will throw LinkageError: duplicate class definition.
1624 // False is the requested default.
1625 // For better performance, the class loaders should synchronize
1626 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1627 // potentially waste time reading and parsing the bytestream.
1628 // Note: VM callers should ensure consistency of k/class_name,class_loader
1629 // Be careful when modifying this code: once you have run
1630 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1631 // you need to find_and_remove it before returning.
1632 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1633 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1634                                                                InstanceKlass* k, TRAPS) {
1635 
1636   Symbol*  name_h = k->name(); // passed in class_name may be null
1637   ClassLoaderData* loader_data = class_loader_data(class_loader);
1638   Dictionary* dictionary = loader_data->dictionary();
1639 
1640   unsigned int d_hash = dictionary->compute_hash(name_h);
1641 
1642   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1643   unsigned int p_hash = placeholders()->compute_hash(name_h);
1644   int p_index = placeholders()->hash_to_index(p_hash);
1645   PlaceholderEntry* probe;
1646 
1647   {
1648     MutexLocker mu(SystemDictionary_lock, THREAD);
1649     // First check if class already defined
1650     if (is_parallelDefine(class_loader)) {
1651       InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1652       if (check != NULL) {
1653         return check;
1654       }
1655     }
1656 
1657     // Acquire define token for this class/classloader
1658     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1659     // Wait if another thread defining in parallel
1660     // All threads wait - even those that will throw duplicate class: otherwise
1661     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1662     // if other thread has not finished updating dictionary
1663     while (probe->definer() != NULL) {
1664       SystemDictionary_lock->wait();
1665     }
1666     // Only special cases allow parallel defines and can use other thread's results
1667     // Other cases fall through, and may run into duplicate defines
1668     // caught by finding an entry in the SystemDictionary
1669     if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1670         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1671         SystemDictionary_lock->notify_all();
1672 #ifdef ASSERT
1673         InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1674         assert(check != NULL, "definer missed recording success");
1675 #endif
1676         return probe->instance_klass();
1677     } else {
1678       // This thread will define the class (even if earlier thread tried and had an error)
1679       probe->set_definer(THREAD);
1680     }
1681   }
1682 
1683   define_instance_class(k, THREAD);
1684 
1685   Handle linkage_exception = Handle(); // null handle
1686 
1687   // definer must notify any waiting threads
1688   {
1689     MutexLocker mu(SystemDictionary_lock, THREAD);
1690     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1691     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1692     if (probe != NULL) {
1693       if (HAS_PENDING_EXCEPTION) {
1694         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1695         CLEAR_PENDING_EXCEPTION;
1696       } else {
1697         probe->set_instance_klass(k);
1698       }
1699       probe->set_definer(NULL);
1700       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1701       SystemDictionary_lock->notify_all();
1702     }
1703   }
1704 
1705   // Can't throw exception while holding lock due to rank ordering
1706   if (linkage_exception() != NULL) {
1707     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1708   }
1709 
1710   return k;
1711 }
1712 
1713 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1714   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1715   if (class_loader.is_null()) {
1716     return Handle(THREAD, _system_loader_lock_obj);
1717   } else {
1718     return class_loader;
1719   }
1720 }
1721 
1722 // This method is added to check how often we have to wait to grab loader
1723 // lock. The results are being recorded in the performance counters defined in
1724 // ClassLoader::_sync_systemLoaderLockContentionRate and
1725 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1726 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1727   if (!UsePerfData) {
1728     return;
1729   }
1730 
1731   assert(!loader_lock.is_null(), "NULL lock object");
1732 
1733   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1734       == ObjectSynchronizer::owner_other) {
1735     // contention will likely happen, so increment the corresponding
1736     // contention counter.
1737     if (loader_lock() == _system_loader_lock_obj) {
1738       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1739     } else {
1740       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1741     }
1742   }
1743 }
1744 
1745 // ----------------------------------------------------------------------------
1746 // Lookup
1747 
1748 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1749                                             Symbol* class_name,
1750                                             Dictionary* dictionary) {
1751   assert_locked_or_safepoint(SystemDictionary_lock);
1752   int index = dictionary->hash_to_index(hash);
1753   return dictionary->find_class(index, hash, class_name);
1754 }
1755 
1756 
1757 // Basic find on classes in the midst of being loaded
1758 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1759                                            ClassLoaderData* loader_data) {
1760   assert_locked_or_safepoint(SystemDictionary_lock);
1761   unsigned int p_hash = placeholders()->compute_hash(class_name);
1762   int p_index = placeholders()->hash_to_index(p_hash);
1763   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1764 }
1765 
1766 
1767 // Used for assertions and verification only
1768 // Precalculating the hash and index is an optimization because there are many lookups
1769 // before adding the class.
1770 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1771   assert_locked_or_safepoint(SystemDictionary_lock);
1772   #ifndef ASSERT
1773   guarantee(VerifyBeforeGC      ||
1774             VerifyDuringGC      ||
1775             VerifyBeforeExit    ||
1776             VerifyDuringStartup ||
1777             VerifyAfterGC, "too expensive");
1778   #endif
1779 
1780   Dictionary* dictionary = loader_data->dictionary();
1781   unsigned int d_hash = dictionary->compute_hash(class_name);
1782   return find_class(d_hash, class_name, dictionary);
1783 }
1784 
1785 
1786 // ----------------------------------------------------------------------------
1787 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1788 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1789 // before a new class is used.
1790 
1791 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1792   assert(k != NULL, "just checking");
1793   assert_locked_or_safepoint(Compile_lock);
1794 
1795   k->set_init_state(InstanceKlass::loaded);
1796   // make sure init_state store is already done.
1797   // The compiler reads the hierarchy outside of the Compile_lock.
1798   // Access ordering is used to add to hierarchy.
1799 
1800   // Link into hierachy.
1801   k->append_to_sibling_list();                    // add to superklass/sibling list
1802   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1803 
1804   // Now flush all code that depended on old class hierarchy.
1805   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1806   CodeCache::flush_dependents_on(k);
1807 }
1808 
1809 // ----------------------------------------------------------------------------
1810 // GC support
1811 
1812 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1813 // Note: anonymous classes are not in the SD.
1814 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1815 
1816   bool unloading_occurred;
1817   bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1818   {
1819     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1820     assert_locked_or_safepoint(ClassLoaderDataGraph_lock);  // caller locks.
1821     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1822     unloading_occurred = ClassLoaderDataGraph::do_unloading();
1823     if (unloading_occurred) {
1824       MutexLocker ml2(is_concurrent ? Module_lock : NULL);
1825       JFR_ONLY(Jfr::on_unloading_classes();)
1826 
1827       MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL);
1828       ClassLoaderDataGraph::clean_module_and_package_info();
1829       constraints()->purge_loader_constraints();
1830       resolution_errors()->purge_resolution_errors();
1831     }
1832   }
1833 
1834   GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1835 
1836   if (unloading_occurred) {
1837     SymbolTable::trigger_cleanup();
1838 
1839     // Oops referenced by the protection domain cache table may get unreachable independently
1840     // of the class loader (eg. cached protection domain oops). So we need to
1841     // explicitly unlink them here.
1842     // All protection domain oops are linked to the caller class, so if nothing
1843     // unloads, this is not needed.
1844     _pd_cache_table->trigger_cleanup();
1845   }
1846 
1847   return unloading_occurred;
1848 }
1849 
1850 void SystemDictionary::oops_do(OopClosure* f, bool include_handles) {
1851   f->do_oop(&_java_system_loader);
1852   f->do_oop(&_java_platform_loader);
1853   f->do_oop(&_system_loader_lock_obj);
1854   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1855 
1856   // Visit extra methods
1857   invoke_method_table()->oops_do(f);
1858 
1859   if (include_handles) {
1860     OopStorageSet::vm_global()->oops_do(f);
1861   }
1862 }
1863 
1864 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1865 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1866   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1867     it->push(well_known_klass_addr((WKID)id));
1868   }
1869 }
1870 
1871 void SystemDictionary::methods_do(void f(Method*)) {
1872   // Walk methods in loaded classes
1873   MutexLocker ml(ClassLoaderDataGraph_lock);
1874   ClassLoaderDataGraph::methods_do(f);
1875   // Walk method handle intrinsics
1876   invoke_method_table()->methods_do(f);
1877 }
1878 
1879 // ----------------------------------------------------------------------------
1880 // Initialization
1881 
1882 void SystemDictionary::initialize(TRAPS) {
1883   // Allocate arrays
1884   _placeholders        = new PlaceholderTable(_placeholder_table_size);
1885   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1886   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1887   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1888   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1889 
1890   // Allocate private object used as system class loader lock
1891   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1892   // Initialize basic classes
1893   resolve_well_known_classes(CHECK);
1894 }
1895 
1896 // Compact table of directions on the initialization of klasses:
1897 static const short wk_init_info[] = {
1898   #define WK_KLASS_INIT_INFO(name, symbol) \
1899     ((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
1900 
1901   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1902   #undef WK_KLASS_INIT_INFO
1903   0
1904 };
1905 
1906 #ifdef ASSERT
1907 bool SystemDictionary::is_well_known_klass(Symbol* class_name) {
1908   int sid;
1909   for (int i = 0; (sid = wk_init_info[i]) != 0; i++) {
1910     Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1911     if (class_name == symbol) {
1912       return true;
1913     }
1914   }
1915   return false;
1916 }
1917 #endif
1918 
1919 bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
1920   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1921   int sid = wk_init_info[id - FIRST_WKID];
1922   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1923   InstanceKlass** klassp = &_well_known_klasses[id];
1924 
1925   if ((*klassp) == NULL) {
1926     Klass* k = resolve_or_fail(symbol, true, CHECK_0);
1927     (*klassp) = InstanceKlass::cast(k);
1928   }
1929   return ((*klassp) != NULL);
1930 }
1931 
1932 void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1933   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1934   for (int id = (int)start_id; id < (int)limit_id; id++) {
1935     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1936     resolve_wk_klass((WKID)id, CHECK);
1937   }
1938 
1939   // move the starting value forward to the limit:
1940   start_id = limit_id;
1941 }
1942 
1943 void SystemDictionary::resolve_well_known_classes(TRAPS) {
1944   assert(WK_KLASS(Object_klass) == NULL, "well-known classes should only be initialized once");
1945 
1946   // Create the ModuleEntry for java.base.  This call needs to be done here,
1947   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
1948   ClassLoader::classLoader_init2(CHECK);
1949 
1950   // Preload commonly used klasses
1951   WKID scan = FIRST_WKID;
1952   // first do Object, then String, Class
1953 #if INCLUDE_CDS
1954   if (UseSharedSpaces) {
1955     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1956 
1957     // It's unsafe to access the archived heap regions before they
1958     // are fixed up, so we must do the fixup as early as possible
1959     // before the archived java objects are accessed by functions
1960     // such as java_lang_Class::restore_archived_mirror and
1961     // ConstantPool::restore_unshareable_info (restores the archived
1962     // resolved_references array object).
1963     //
1964     // HeapShared::fixup_mapped_heap_regions() fills the empty
1965     // spaces in the archived heap regions and may use
1966     // SystemDictionary::Object_klass(), so we can do this only after
1967     // Object_klass is resolved. See the above resolve_wk_klasses_through()
1968     // call. No mirror objects are accessed/restored in the above call.
1969     // Mirrors are restored after java.lang.Class is loaded.
1970     HeapShared::fixup_mapped_heap_regions();
1971 
1972     // Initialize the constant pool for the Object_class
1973     assert(Object_klass()->is_shared(), "must be");
1974     Object_klass()->constants()->restore_unshareable_info(CHECK);
1975     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1976   } else
1977 #endif
1978   {
1979     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1980   }
1981 
1982   // Calculate offsets for String and Class classes since they are loaded and
1983   // can be used after this point.
1984   java_lang_String::compute_offsets();
1985   java_lang_Class::compute_offsets();
1986 
1987   // Fixup mirrors for classes loaded before java.lang.Class.
1988   // These calls iterate over the objects currently in the perm gen
1989   // so calling them at this point is matters (not before when there
1990   // are fewer objects and not later after there are more objects
1991   // in the perm gen.
1992   Universe::initialize_basic_type_mirrors(CHECK);
1993   Universe::fixup_mirrors(CHECK);
1994 
1995   // do a bunch more:
1996   resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1997 
1998   // Preload ref klasses and set reference types
1999   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2000   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2001 
2002   resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2003   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2004   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2005   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2006   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2007 
2008   // JSR 292 classes
2009   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2010   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2011   resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
2012   resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
2013   WKID last = WKID_LIMIT;
2014   resolve_wk_klasses_until(last, scan, CHECK);
2015 
2016   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2017   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2018   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2019   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2020   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2021   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2022   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2023   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2024   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2025   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2026 
2027   { // Compute whether we should use checkPackageAccess or NOT
2028     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2029     _has_checkPackageAccess = (method != NULL);
2030   }
2031 
2032 #ifdef ASSERT
2033   if (UseSharedSpaces) {
2034     assert(JvmtiExport::is_early_phase(),
2035            "All well known classes must be resolved in JVMTI early phase");
2036     for (int i = FIRST_WKID; i < last; i++) {
2037       InstanceKlass* k = _well_known_klasses[i];
2038       assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
2039     }
2040   }
2041 #endif
2042 }
2043 
2044 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2045 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2046 BasicType SystemDictionary::box_klass_type(Klass* k) {
2047   assert(k != NULL, "");
2048   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2049     if (_box_klasses[i] == k)
2050       return (BasicType)i;
2051   }
2052   return T_OBJECT;
2053 }
2054 
2055 // Constraints on class loaders. The details of the algorithm can be
2056 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2057 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2058 // that the dictionary needs to maintain a set of contraints that
2059 // must be satisfied by all classes in the dictionary.
2060 // if defining is true, then LinkageError if already in dictionary
2061 // if initiating loader, then ok if InstanceKlass matches existing entry
2062 
2063 void SystemDictionary::check_constraints(unsigned int d_hash,
2064                                          InstanceKlass* k,
2065                                          Handle class_loader,
2066                                          bool defining,
2067                                          TRAPS) {
2068   ResourceMark rm(THREAD);
2069   stringStream ss;
2070   bool throwException = false;
2071 
2072   {
2073     Symbol *name = k->name();
2074     ClassLoaderData *loader_data = class_loader_data(class_loader);
2075 
2076     MutexLocker mu(SystemDictionary_lock, THREAD);
2077 
2078     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2079     if (check != NULL) {
2080       // If different InstanceKlass - duplicate class definition,
2081       // else - ok, class loaded by a different thread in parallel.
2082       // We should only have found it if it was done loading and ok to use.
2083       // The dictionary only holds instance classes, placeholders
2084       // also hold array classes.
2085 
2086       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2087       if ((defining == true) || (k != check)) {
2088         throwException = true;
2089         ss.print("loader %s", loader_data->loader_name_and_id());
2090         ss.print(" attempted duplicate %s definition for %s. (%s)",
2091                  k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
2092       } else {
2093         return;
2094       }
2095     }
2096 
2097 #ifdef ASSERT
2098     Symbol* ph_check = find_placeholder(name, loader_data);
2099     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2100 #endif
2101 
2102     if (throwException == false) {
2103       if (constraints()->check_or_update(k, class_loader, name) == false) {
2104         throwException = true;
2105         ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
2106         ss.print(" wants to load %s %s.",
2107                  k->external_kind(), k->external_name());
2108         Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2109         if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
2110           ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
2111                    existing_klass->external_kind(),
2112                    existing_klass->class_loader_data()->loader_name_and_id(),
2113                    existing_klass->class_in_module_of_loader(false, true));
2114         } else {
2115           ss.print(" (%s)", k->class_in_module_of_loader(false, true));
2116         }
2117       }
2118     }
2119   }
2120 
2121   // Throw error now if needed (cannot throw while holding
2122   // SystemDictionary_lock because of rank ordering)
2123   if (throwException == true) {
2124     THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2125   }
2126 }
2127 
2128 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2129 // have been called.
2130 void SystemDictionary::update_dictionary(unsigned int d_hash,
2131                                          int p_index, unsigned int p_hash,
2132                                          InstanceKlass* k,
2133                                          Handle class_loader,
2134                                          TRAPS) {
2135   // Compile_lock prevents systemDictionary updates during compilations
2136   assert_locked_or_safepoint(Compile_lock);
2137   Symbol*  name  = k->name();
2138   ClassLoaderData *loader_data = class_loader_data(class_loader);
2139 
2140   {
2141     MutexLocker mu1(SystemDictionary_lock, THREAD);
2142 
2143     // See whether biased locking is enabled and if so set it for this
2144     // klass.
2145     // Note that this must be done past the last potential blocking
2146     // point / safepoint. We might enable biased locking lazily using a
2147     // VM_Operation to iterate the SystemDictionary and installing the
2148     // biasable mark word into each InstanceKlass's prototype header.
2149     // To avoid race conditions where we accidentally miss enabling the
2150     // optimization for one class in the process of being added to the
2151     // dictionary, we must not safepoint after the test of
2152     // BiasedLocking::enabled().
2153     if (UseBiasedLocking && BiasedLocking::enabled()) {
2154       // Set biased locking bit for all loaded classes; it will be
2155       // cleared if revocation occurs too often for this type
2156       // NOTE that we must only do this when the class is initally
2157       // defined, not each time it is referenced from a new class loader
2158       if (k->class_loader() == class_loader()) {
2159         k->set_prototype_header(markWord::biased_locking_prototype());
2160       }
2161     }
2162 
2163     // Make a new dictionary entry.
2164     Dictionary* dictionary = loader_data->dictionary();
2165     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2166     if (sd_check == NULL) {
2167       dictionary->add_klass(d_hash, name, k);
2168     }
2169   #ifdef ASSERT
2170     sd_check = find_class(d_hash, name, dictionary);
2171     assert (sd_check != NULL, "should have entry in dictionary");
2172     // Note: there may be a placeholder entry: for circularity testing
2173     // or for parallel defines
2174   #endif
2175     SystemDictionary_lock->notify_all();
2176   }
2177 }
2178 
2179 
2180 // Try to find a class name using the loader constraints.  The
2181 // loader constraints might know about a class that isn't fully loaded
2182 // yet and these will be ignored.
2183 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2184                     Symbol* class_name, Handle class_loader, TRAPS) {
2185 
2186   // First see if it has been loaded directly.
2187   // Force the protection domain to be null.  (This removes protection checks.)
2188   Handle no_protection_domain;
2189   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2190                                               no_protection_domain, CHECK_NULL);
2191   if (klass != NULL)
2192     return klass;
2193 
2194   // Now look to see if it has been loaded elsewhere, and is subject to
2195   // a loader constraint that would require this loader to return the
2196   // klass that is already loaded.
2197   if (FieldType::is_array(class_name)) {
2198     // For array classes, their Klass*s are not kept in the
2199     // constraint table. The element Klass*s are.
2200     FieldArrayInfo fd;
2201     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2202     if (t != T_OBJECT) {
2203       klass = Universe::typeArrayKlassObj(t);
2204     } else {
2205       MutexLocker mu(SystemDictionary_lock, THREAD);
2206       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2207     }
2208     // If element class already loaded, allocate array klass
2209     if (klass != NULL) {
2210       klass = klass->array_klass_or_null(fd.dimension());
2211     }
2212   } else {
2213     MutexLocker mu(SystemDictionary_lock, THREAD);
2214     // Non-array classes are easy: simply check the constraint table.
2215     klass = constraints()->find_constrained_klass(class_name, class_loader);
2216   }
2217 
2218   return klass;
2219 }
2220 
2221 
2222 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2223                                              Handle class_loader1,
2224                                              Handle class_loader2,
2225                                              Thread* THREAD) {
2226   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2227   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2228 
2229   Symbol* constraint_name = NULL;
2230   // Needs to be in same scope as constraint_name in case a Symbol is created and
2231   // assigned to constraint_name.
2232   FieldArrayInfo fd;
2233   if (!FieldType::is_array(class_name)) {
2234     constraint_name = class_name;
2235   } else {
2236     // For array classes, their Klass*s are not kept in the
2237     // constraint table. The element classes are.
2238     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2239     // primitive types always pass
2240     if (t != T_OBJECT) {
2241       return true;
2242     } else {
2243       constraint_name = fd.object_key();
2244     }
2245   }
2246 
2247   Dictionary* dictionary1 = loader_data1->dictionary();
2248   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2249 
2250   Dictionary* dictionary2 = loader_data2->dictionary();
2251   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2252 
2253   {
2254     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2255     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2256     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2257     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2258                                     klass2, class_loader2);
2259   }
2260 }
2261 
2262 // Add entry to resolution error table to record the error when the first
2263 // attempt to resolve a reference to a class has failed.
2264 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2265                                             Symbol* error, Symbol* message) {
2266   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2267   int index = resolution_errors()->hash_to_index(hash);
2268   {
2269     MutexLocker ml(SystemDictionary_lock, Thread::current());
2270     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2271   }
2272 }
2273 
2274 // Delete a resolution error for RedefineClasses for a constant pool is going away
2275 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2276   resolution_errors()->delete_entry(pool);
2277 }
2278 
2279 // Lookup resolution error table. Returns error if found, otherwise NULL.
2280 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2281                                                 Symbol** message) {
2282   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2283   int index = resolution_errors()->hash_to_index(hash);
2284   {
2285     MutexLocker ml(SystemDictionary_lock, Thread::current());
2286     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2287     if (entry != NULL) {
2288       *message = entry->message();
2289       return entry->error();
2290     } else {
2291       return NULL;
2292     }
2293   }
2294 }
2295 
2296 
2297 // Signature constraints ensure that callers and callees agree about
2298 // the meaning of type names in their signatures.  This routine is the
2299 // intake for constraints.  It collects them from several places:
2300 //
2301 //  * LinkResolver::resolve_method (if check_access is true) requires
2302 //    that the resolving class (the caller) and the defining class of
2303 //    the resolved method (the callee) agree on each type in the
2304 //    method's signature.
2305 //
2306 //  * LinkResolver::resolve_interface_method performs exactly the same
2307 //    checks.
2308 //
2309 //  * LinkResolver::resolve_field requires that the constant pool
2310 //    attempting to link to a field agree with the field's defining
2311 //    class about the type of the field signature.
2312 //
2313 //  * klassVtable::initialize_vtable requires that, when a class
2314 //    overrides a vtable entry allocated by a superclass, that the
2315 //    overriding method (i.e., the callee) agree with the superclass
2316 //    on each type in the method's signature.
2317 //
2318 //  * klassItable::initialize_itable requires that, when a class fills
2319 //    in its itables, for each non-abstract method installed in an
2320 //    itable, the method (i.e., the callee) agree with the interface
2321 //    on each type in the method's signature.
2322 //
2323 // All those methods have a boolean (check_access, checkconstraints)
2324 // which turns off the checks.  This is used from specialized contexts
2325 // such as bootstrapping, dumping, and debugging.
2326 //
2327 // No direct constraint is placed between the class and its
2328 // supertypes.  Constraints are only placed along linked relations
2329 // between callers and callees.  When a method overrides or implements
2330 // an abstract method in a supertype (superclass or interface), the
2331 // constraints are placed as if the supertype were the caller to the
2332 // overriding method.  (This works well, since callers to the
2333 // supertype have already established agreement between themselves and
2334 // the supertype.)  As a result of all this, a class can disagree with
2335 // its supertype about the meaning of a type name, as long as that
2336 // class neither calls a relevant method of the supertype, nor is
2337 // called (perhaps via an override) from the supertype.
2338 //
2339 //
2340 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2341 //
2342 // Make sure all class components (including arrays) in the given
2343 // signature will be resolved to the same class in both loaders.
2344 // Returns the name of the type that failed a loader constraint check, or
2345 // NULL if no constraint failed.  No exception except OOME is thrown.
2346 // Arrays are not added to the loader constraint table, their elements are.
2347 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2348                                                Handle loader1, Handle loader2,
2349                                                bool is_method, TRAPS)  {
2350   // Nothing to do if loaders are the same.
2351   if (loader1() == loader2()) {
2352     return NULL;
2353   }
2354 
2355   SignatureStream sig_strm(signature, is_method);
2356   while (!sig_strm.is_done()) {
2357     if (sig_strm.is_object()) {
2358       Symbol* sig = sig_strm.as_symbol();
2359       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2360         return sig;
2361       }
2362     }
2363     sig_strm.next();
2364   }
2365   return NULL;
2366 }
2367 
2368 
2369 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2370                                                             Symbol* signature,
2371                                                             TRAPS) {
2372   methodHandle empty;
2373   assert(MethodHandles::is_signature_polymorphic(iid) &&
2374          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2375          iid != vmIntrinsics::_invokeGeneric,
2376          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2377 
2378   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2379   int          index = invoke_method_table()->hash_to_index(hash);
2380   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2381   methodHandle m;
2382   if (spe == NULL || spe->method() == NULL) {
2383     spe = NULL;
2384     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2385     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2386     if (!Arguments::is_interpreter_only()) {
2387       // Generate a compiled form of the MH intrinsic.
2388       AdapterHandlerLibrary::create_native_wrapper(m);
2389       // Check if have the compiled code.
2390       if (!m->has_compiled_code()) {
2391         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2392                    "Out of space in CodeCache for method handle intrinsic", empty);
2393       }
2394     }
2395     // Now grab the lock.  We might have to throw away the new method,
2396     // if a racing thread has managed to install one at the same time.
2397     {
2398       MutexLocker ml(SystemDictionary_lock, THREAD);
2399       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2400       if (spe == NULL)
2401         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2402       if (spe->method() == NULL)
2403         spe->set_method(m());
2404     }
2405   }
2406 
2407   assert(spe != NULL && spe->method() != NULL, "");
2408   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2409          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2410          "MH intrinsic invariant");
2411   return spe->method();
2412 }
2413 
2414 // Helper for unpacking the return value from linkMethod and linkCallSite.
2415 static methodHandle unpack_method_and_appendix(Handle mname,
2416                                                Klass* accessing_klass,
2417                                                objArrayHandle appendix_box,
2418                                                Handle* appendix_result,
2419                                                TRAPS) {
2420   methodHandle empty;
2421   if (mname.not_null()) {
2422     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2423     if (m != NULL) {
2424       oop appendix = appendix_box->obj_at(0);
2425       if (TraceMethodHandles) {
2426     #ifndef PRODUCT
2427         ttyLocker ttyl;
2428         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2429         m->print();
2430         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2431         tty->cr();
2432     #endif //PRODUCT
2433       }
2434       (*appendix_result) = Handle(THREAD, appendix);
2435       // the target is stored in the cpCache and if a reference to this
2436       // MemberName is dropped we need a way to make sure the
2437       // class_loader containing this method is kept alive.
2438       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2439       this_key->record_dependency(m->method_holder());
2440       return methodHandle(THREAD, m);
2441     }
2442   }
2443   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2444   return empty;
2445 }
2446 
2447 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2448                                                           Symbol* name,
2449                                                           Symbol* signature,
2450                                                           Klass* accessing_klass,
2451                                                           Handle *appendix_result,
2452                                                           TRAPS) {
2453   methodHandle empty;
2454   assert(THREAD->can_call_java() ,"");
2455   Handle method_type =
2456     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2457 
2458   int ref_kind = JVM_REF_invokeVirtual;
2459   oop name_oop = StringTable::intern(name, CHECK_(empty));
2460   Handle name_str (THREAD, name_oop);
2461   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2462   assert(appendix_box->obj_at(0) == NULL, "");
2463 
2464   // This should not happen.  JDK code should take care of that.
2465   if (accessing_klass == NULL || method_type.is_null()) {
2466     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2467   }
2468 
2469   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2470   JavaCallArguments args;
2471   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2472   args.push_int(ref_kind);
2473   args.push_oop(Handle(THREAD, klass->java_mirror()));
2474   args.push_oop(name_str);
2475   args.push_oop(method_type);
2476   args.push_oop(appendix_box);
2477   JavaValue result(T_OBJECT);
2478   JavaCalls::call_static(&result,
2479                          SystemDictionary::MethodHandleNatives_klass(),
2480                          vmSymbols::linkMethod_name(),
2481                          vmSymbols::linkMethod_signature(),
2482                          &args, CHECK_(empty));
2483   Handle mname(THREAD, (oop) result.get_jobject());
2484   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2485 }
2486 
2487 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2488 // We must ensure that all class loaders everywhere will reach this class, for any client.
2489 // This is a safe bet for public classes in java.lang, such as Object and String.
2490 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2491 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2492 static bool is_always_visible_class(oop mirror) {
2493   Klass* klass = java_lang_Class::as_Klass(mirror);
2494   if (klass->is_objArray_klass()) {
2495     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2496   }
2497   if (klass->is_typeArray_klass()) {
2498     return true; // primitive array
2499   }
2500   assert(klass->is_instance_klass(), "%s", klass->external_name());
2501   return klass->is_public() &&
2502          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2503           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2504 }
2505 
2506 
2507 // Return the Java mirror (java.lang.Class instance) for a single-character
2508 // descriptor.  This result, when available, is the same as produced by the
2509 // heavier API point of the same name that takes a Symbol.
2510 oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
2511   return java_lang_Class::primitive_mirror(char2type(signature_char));
2512 }
2513 
2514 // Find or construct the Java mirror (java.lang.Class instance) for a
2515 // for the given field type signature, as interpreted relative to the
2516 // given class loader.  Handles primitives, void, references, arrays,
2517 // and all other reflectable types, except method types.
2518 // N.B.  Code in reflection should use this entry point.
2519 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2520                                                    Klass* accessing_klass,
2521                                                    Handle class_loader,
2522                                                    Handle protection_domain,
2523                                                    SignatureStream::FailureMode failure_mode,
2524                                                    TRAPS) {
2525   Handle empty;
2526 
2527   assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2528          "one or the other, or perhaps neither");
2529 
2530   Symbol* type = signature;
2531 
2532   // What we have here must be a valid field descriptor,
2533   // and all valid field descriptors are supported.
2534   // Produce the same java.lang.Class that reflection reports.
2535   if (type->utf8_length() == 1) {
2536 
2537     // It's a primitive.  (Void has a primitive mirror too.)
2538     char ch = type->char_at(0);
2539     assert(is_java_primitive(char2type(ch)) || ch == 'V', "");
2540     return Handle(THREAD, find_java_mirror_for_type(ch));
2541 
2542   } else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
2543 
2544     // It's a reference type.
2545     if (accessing_klass != NULL) {
2546       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2547       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2548     }
2549     Klass* constant_type_klass;
2550     if (failure_mode == SignatureStream::ReturnNull) {
2551       constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
2552                                             CHECK_(empty));
2553     } else {
2554       bool throw_error = (failure_mode == SignatureStream::NCDFError);
2555       constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
2556                                             throw_error, CHECK_(empty));
2557     }
2558     if (constant_type_klass == NULL) {
2559       return Handle();  // report failure this way
2560     }
2561     Handle mirror(THREAD, constant_type_klass->java_mirror());
2562 
2563     // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2564     if (accessing_klass != NULL) {
2565       Klass* sel_klass = constant_type_klass;
2566       bool fold_type_to_class = true;
2567       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2568                                               fold_type_to_class, CHECK_(empty));
2569     }
2570 
2571     return mirror;
2572 
2573   }
2574 
2575   // Fall through to an error.
2576   assert(false, "unsupported mirror syntax");
2577   THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2578 }
2579 
2580 
2581 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2582 // signature, as interpreted relative to the given class loader.
2583 // Because of class loader constraints, all method handle usage must be
2584 // consistent with this loader.
2585 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2586                                                  Klass* accessing_klass,
2587                                                  TRAPS) {
2588   Handle empty;
2589   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2590   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2591   int          index = invoke_method_table()->hash_to_index(hash);
2592   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2593   if (spe != NULL && spe->method_type() != NULL) {
2594     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2595     return Handle(THREAD, spe->method_type());
2596   } else if (!THREAD->can_call_java()) {
2597     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2598     return Handle();  // do not attempt from within compiler, unless it was cached
2599   }
2600 
2601   Handle class_loader, protection_domain;
2602   if (accessing_klass != NULL) {
2603     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2604     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2605   }
2606   bool can_be_cached = true;
2607   int npts = ArgumentCount(signature).size();
2608   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2609   int arg = 0;
2610   Handle rt; // the return type from the signature
2611   ResourceMark rm(THREAD);
2612   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2613     oop mirror = NULL;
2614     if (can_be_cached) {
2615       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2616       mirror = ss.as_java_mirror(Handle(), Handle(),
2617                                  SignatureStream::ReturnNull, CHECK_(empty));
2618       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2619         // Fall back to accessing_klass context.
2620         can_be_cached = false;
2621       }
2622     }
2623     if (!can_be_cached) {
2624       // Resolve, throwing a real error if it doesn't work.
2625       mirror = ss.as_java_mirror(class_loader, protection_domain,
2626                                  SignatureStream::NCDFError, CHECK_(empty));
2627     }
2628     assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string());
2629     if (ss.at_return_type())
2630       rt = Handle(THREAD, mirror);
2631     else
2632       pts->obj_at_put(arg++, mirror);
2633 
2634     // Check accessibility.
2635     if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2636       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2637       mirror = NULL;  // safety
2638       // Emulate ConstantPool::verify_constant_pool_resolve.
2639       bool fold_type_to_class = true;
2640       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2641                                               fold_type_to_class, CHECK_(empty));
2642     }
2643   }
2644   assert(arg == npts, "");
2645 
2646   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2647   JavaCallArguments args(Handle(THREAD, rt()));
2648   args.push_oop(pts);
2649   JavaValue result(T_OBJECT);
2650   JavaCalls::call_static(&result,
2651                          SystemDictionary::MethodHandleNatives_klass(),
2652                          vmSymbols::findMethodHandleType_name(),
2653                          vmSymbols::findMethodHandleType_signature(),
2654                          &args, CHECK_(empty));
2655   Handle method_type(THREAD, (oop) result.get_jobject());
2656 
2657   if (can_be_cached) {
2658     // We can cache this MethodType inside the JVM.
2659     MutexLocker ml(SystemDictionary_lock, THREAD);
2660     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2661     if (spe == NULL)
2662       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2663     if (spe->method_type() == NULL) {
2664       spe->set_method_type(method_type());
2665     }
2666   }
2667 
2668   // report back to the caller with the MethodType
2669   return method_type;
2670 }
2671 
2672 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2673                                                 Klass* accessing_klass,
2674                                                 TRAPS) {
2675   Handle empty;
2676   ResourceMark rm(THREAD);
2677   SignatureStream ss(signature, /*is_method=*/ false);
2678   if (!ss.is_done()) {
2679     Handle class_loader, protection_domain;
2680     if (accessing_klass != NULL) {
2681       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2682       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2683     }
2684     oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2685     ss.next();
2686     if (ss.is_done()) {
2687       return Handle(THREAD, mirror);
2688     }
2689   }
2690   return empty;
2691 }
2692 
2693 // Ask Java code to find or construct a method handle constant.
2694 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2695                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2696                                                      Klass* callee,
2697                                                      Symbol* name,
2698                                                      Symbol* signature,
2699                                                      TRAPS) {
2700   Handle empty;
2701   if (caller == NULL) {
2702     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2703   }
2704   Handle name_str      = java_lang_String::create_from_symbol(name,      CHECK_(empty));
2705   Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2706 
2707   // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2708   Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2709   java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2710   java_lang_invoke_MemberName::set_name (mname(), name_str());
2711   java_lang_invoke_MemberName::set_type (mname(), signature_str());
2712   java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2713 
2714   if (ref_kind == JVM_REF_invokeVirtual &&
2715       MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2716     // Skip resolution for public signature polymorphic methods such as
2717     // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2718     // They require appendix argument which MemberName resolution doesn't handle.
2719     // There's special logic on JDK side to handle them
2720     // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2721   } else {
2722     MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2723   }
2724 
2725   // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2726   Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2727 
2728   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2729   JavaCallArguments args;
2730   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2731   args.push_int(ref_kind);
2732   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2733   args.push_oop(name_str);
2734   args.push_oop(type);
2735   JavaValue result(T_OBJECT);
2736   JavaCalls::call_static(&result,
2737                          SystemDictionary::MethodHandleNatives_klass(),
2738                          vmSymbols::linkMethodHandleConstant_name(),
2739                          vmSymbols::linkMethodHandleConstant_signature(),
2740                          &args, CHECK_(empty));
2741   return Handle(THREAD, (oop) result.get_jobject());
2742 }
2743 
2744 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2745 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2746 // with linkage results being stored back into the bootstrap specifier.
2747 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2748   // Resolve the bootstrap specifier, its name, type, and static arguments
2749   bootstrap_specifier.resolve_bsm(CHECK);
2750 
2751   // This should not happen.  JDK code should take care of that.
2752   if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
2753     THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2754   }
2755 
2756   bool is_indy = bootstrap_specifier.is_method_call();
2757   objArrayHandle appendix_box;
2758   if (is_indy) {
2759     // Some method calls may require an appendix argument.  Arrange to receive it.
2760     appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK);
2761     assert(appendix_box->obj_at(0) == NULL, "");
2762   }
2763 
2764   // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, condy_index, bsm, type, info)
2765   //       indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2766   JavaCallArguments args;
2767   args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2768   args.push_int(bootstrap_specifier.bss_index());
2769   args.push_oop(bootstrap_specifier.bsm());
2770   args.push_oop(bootstrap_specifier.name_arg());
2771   args.push_oop(bootstrap_specifier.type_arg());
2772   args.push_oop(bootstrap_specifier.arg_values());
2773   if (is_indy) {
2774     args.push_oop(appendix_box);
2775   }
2776   JavaValue result(T_OBJECT);
2777   JavaCalls::call_static(&result,
2778                          SystemDictionary::MethodHandleNatives_klass(),
2779                          is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2780                          is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2781                          &args, CHECK);
2782 
2783   Handle value(THREAD, (oop) result.get_jobject());
2784   if (is_indy) {
2785     Handle appendix;
2786     methodHandle method = unpack_method_and_appendix(value,
2787                                                      bootstrap_specifier.caller(),
2788                                                      appendix_box,
2789                                                      &appendix, CHECK);
2790     bootstrap_specifier.set_resolved_method(method, appendix);
2791   } else {
2792     bootstrap_specifier.set_resolved_value(value);
2793   }
2794 
2795   // sanity check
2796   assert(bootstrap_specifier.is_resolved() ||
2797          (bootstrap_specifier.is_method_call() &&
2798           bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2799 }
2800 
2801 // Protection domain cache table handling
2802 
2803 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2804   return _pd_cache_table->get(protection_domain);
2805 }
2806 
2807 // ----------------------------------------------------------------------------
2808 
2809 void SystemDictionary::print_on(outputStream *st) {
2810   CDS_ONLY(SystemDictionaryShared::print_on(st));
2811   GCMutexLocker mu(SystemDictionary_lock);
2812 
2813   ClassLoaderDataGraph::print_dictionary(st);
2814 
2815   // Placeholders
2816   placeholders()->print_on(st);
2817   st->cr();
2818 
2819   // loader constraints - print under SD_lock
2820   constraints()->print_on(st);
2821   st->cr();
2822 
2823   _pd_cache_table->print_on(st);
2824   st->cr();
2825 }
2826 
2827 void SystemDictionary::print() { print_on(tty); }
2828 
2829 void SystemDictionary::verify() {
2830   guarantee(constraints() != NULL,
2831             "Verify of loader constraints failed");
2832   guarantee(placeholders()->number_of_entries() >= 0,
2833             "Verify of placeholders failed");
2834 
2835   GCMutexLocker mu(SystemDictionary_lock);
2836 
2837   // Verify dictionary
2838   ClassLoaderDataGraph::verify_dictionary();
2839 
2840   placeholders()->verify();
2841 
2842   // Verify constraint table
2843   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2844   constraints()->verify(placeholders());
2845 
2846   _pd_cache_table->verify();
2847 }
2848 
2849 void SystemDictionary::dump(outputStream *st, bool verbose) {
2850   assert_locked_or_safepoint(SystemDictionary_lock);
2851   if (verbose) {
2852     print_on(st);
2853   } else {
2854     CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2855     ClassLoaderDataGraph::print_table_statistics(st);
2856     placeholders()->print_table_statistics(st, "Placeholder Table");
2857     constraints()->print_table_statistics(st, "LoaderConstraints Table");
2858     pd_cache_table()->print_table_statistics(st, "ProtectionDomainCache Table");
2859   }
2860 }
2861 
2862 TableStatistics SystemDictionary::placeholders_statistics() {
2863   MutexLocker ml(SystemDictionary_lock);
2864   return placeholders()->statistics_calculate();
2865 }
2866 
2867 TableStatistics SystemDictionary::loader_constraints_statistics() {
2868   MutexLocker ml(SystemDictionary_lock);
2869   return constraints()->statistics_calculate();
2870 }
2871 
2872 TableStatistics SystemDictionary::protection_domain_cache_statistics() {
2873   MutexLocker ml(SystemDictionary_lock);
2874   return pd_cache_table()->statistics_calculate();
2875 }
2876 
2877 // Utility for dumping dictionaries.
2878 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2879                                  DCmdWithParser(output, heap),
2880   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2881            "BOOLEAN", false, "false") {
2882   _dcmdparser.add_dcmd_option(&_verbose);
2883 }
2884 
2885 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2886   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2887                          _verbose.value());
2888   VMThread::execute(&dumper);
2889 }
2890 
2891 int SystemDictionaryDCmd::num_arguments() {
2892   ResourceMark rm;
2893   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
2894   if (dcmd != NULL) {
2895     DCmdMark mark(dcmd);
2896     return dcmd->_dcmdparser.num_arguments();
2897   } else {
2898     return 0;
2899   }
2900 }