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/systemDictionary.hpp"
  44 #include "classfile/vmSymbols.hpp"
  45 #include "code/codeCache.hpp"
  46 #include "compiler/compileBroker.hpp"
  47 #include "gc/shared/gcTraceTime.inline.hpp"
  48 #include "gc/shared/oopStorage.inline.hpp"
  49 #include "interpreter/bytecodeStream.hpp"
  50 #include "interpreter/interpreter.hpp"
  51 #include "jfr/jfrEvents.hpp"
  52 #include "logging/log.hpp"
  53 #include "logging/logStream.hpp"
  54 #include "memory/filemap.hpp"
  55 #include "memory/heapShared.hpp"
  56 #include "memory/metaspaceClosure.hpp"
  57 #include "memory/oopFactory.hpp"
  58 #include "memory/resourceArea.hpp"
  59 #include "oops/access.inline.hpp"
  60 #include "oops/instanceKlass.hpp"
  61 #include "oops/instanceRefKlass.hpp"
  62 #include "oops/klass.inline.hpp"
  63 #include "oops/method.inline.hpp"
  64 #include "oops/methodData.hpp"
  65 #include "oops/objArrayKlass.hpp"
  66 #include "oops/objArrayOop.inline.hpp"
  67 #include "oops/oop.inline.hpp"
  68 #include "oops/symbol.hpp"
  69 #include "oops/typeArrayKlass.hpp"
  70 #include "prims/jvmtiExport.hpp"
  71 #include "prims/methodHandles.hpp"
  72 #include "runtime/arguments.hpp"
  73 #include "runtime/biasedLocking.hpp"
  74 #include "runtime/fieldType.hpp"
  75 #include "runtime/handles.inline.hpp"
  76 #include "runtime/java.hpp"
  77 #include "runtime/javaCalls.hpp"
  78 #include "runtime/mutexLocker.hpp"
  79 #include "runtime/orderAccess.hpp"
  80 #include "runtime/sharedRuntime.hpp"
  81 #include "runtime/signature.hpp"
  82 #include "services/classLoadingService.hpp"
  83 #include "services/diagnosticCommand.hpp"
  84 #include "services/threadService.hpp"
  85 #include "utilities/macros.hpp"
  86 #if INCLUDE_CDS
  87 #include "classfile/systemDictionaryShared.hpp"
  88 #endif
  89 #if INCLUDE_JFR
  90 #include "jfr/jfr.hpp"
  91 #endif
  92 
  93 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  94 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  95 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  96 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
  97 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
  98 
  99 int         SystemDictionary::_number_of_modifications = 0;
 100 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 101 
 102 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 103                                                           =  { NULL /*, NULL...*/ };
 104 
 105 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 106 
 107 oop         SystemDictionary::_java_system_loader         =  NULL;
 108 oop         SystemDictionary::_java_platform_loader       =  NULL;
 109 
 110 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 111 
 112 // Default ProtectionDomainCacheSize value
 113 
 114 const int defaultProtectionDomainCacheSize = 1009;
 115 
 116 OopStorage* SystemDictionary::_vm_weak_oop_storage = NULL;
 117 
 118 
 119 // ----------------------------------------------------------------------------
 120 // Java-level SystemLoader and PlatformLoader
 121 
 122 oop SystemDictionary::java_system_loader() {
 123   return _java_system_loader;
 124 }
 125 
 126 oop SystemDictionary::java_platform_loader() {
 127   return _java_platform_loader;
 128 }
 129 
 130 void SystemDictionary::compute_java_loaders(TRAPS) {
 131   JavaValue result(T_OBJECT);
 132   InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
 133   JavaCalls::call_static(&result,
 134                          class_loader_klass,
 135                          vmSymbols::getSystemClassLoader_name(),
 136                          vmSymbols::void_classloader_signature(),
 137                          CHECK);
 138 
 139   _java_system_loader = (oop)result.get_jobject();
 140 
 141   JavaCalls::call_static(&result,
 142                          class_loader_klass,
 143                          vmSymbols::getPlatformClassLoader_name(),
 144                          vmSymbols::void_classloader_signature(),
 145                          CHECK);
 146 
 147   _java_platform_loader = (oop)result.get_jobject();
 148 }
 149 
 150 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
 151   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 152   return ClassLoaderDataGraph::find_or_create(class_loader);
 153 }
 154 
 155 // ----------------------------------------------------------------------------
 156 // Parallel class loading check
 157 
 158 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 159   if (class_loader.is_null()) return true;
 160   if (AlwaysLockClassLoader) return false;
 161   return java_lang_ClassLoader::parallelCapable(class_loader());
 162 }
 163 // ----------------------------------------------------------------------------
 164 // ParallelDefineClass flag does not apply to bootclass loader
 165 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 166    if (class_loader.is_null()) return false;
 167    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 168      return true;
 169    }
 170    return false;
 171 }
 172 
 173 // Returns true if the passed class loader is the builtin application class loader
 174 // or a custom system class loader. A customer system class loader can be
 175 // specified via -Djava.system.class.loader.
 176 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 177   if (class_loader == NULL) {
 178     return false;
 179   }
 180   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 181          oopDesc::equals(class_loader, _java_system_loader));
 182 }
 183 
 184 // Returns true if the passed class loader is the platform class loader.
 185 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 186   if (class_loader == NULL) {
 187     return false;
 188   }
 189   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 190 }
 191 
 192 // ----------------------------------------------------------------------------
 193 // Resolving of classes
 194 
 195 // Forwards to resolve_or_null
 196 
 197 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 198   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 199   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 200     // can return a null klass
 201     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 202   }
 203   return klass;
 204 }
 205 
 206 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 207                                                      bool throw_error,
 208                                                      Klass* klass, TRAPS) {
 209   if (HAS_PENDING_EXCEPTION) {
 210     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 211     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 212     // and if so convert it to a NoClassDefFoundError
 213     // And chain the original ClassNotFoundException
 214     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 215       ResourceMark rm(THREAD);
 216       assert(klass == NULL, "Should not have result with exception pending");
 217       Handle e(THREAD, PENDING_EXCEPTION);
 218       CLEAR_PENDING_EXCEPTION;
 219       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 220     } else {
 221       return NULL;
 222     }
 223   }
 224   // Class not found, throw appropriate error or exception depending on value of throw_error
 225   if (klass == NULL) {
 226     ResourceMark rm(THREAD);
 227     if (throw_error) {
 228       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 229     } else {
 230       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 231     }
 232   }
 233   return klass;
 234 }
 235 
 236 
 237 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 238                                            bool throw_error, TRAPS)
 239 {
 240   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 241 }
 242 
 243 
 244 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
 245 
 246 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 247   if (FieldType::is_array(class_name)) {
 248     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 249   } else {
 250     return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
 251   }
 252 }
 253 
 254 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
 255 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
 256                                                                        Handle class_loader,
 257                                                                        Handle protection_domain,
 258                                                                        TRAPS) {
 259   assert(class_name != NULL && !FieldType::is_array(class_name), "must be");
 260   if (FieldType::is_obj(class_name)) {
 261     ResourceMark rm(THREAD);
 262     // Ignore wrapping L and ;.
 263     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 264                                    class_name->utf8_length() - 2, CHECK_NULL);
 265     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 266   } else {
 267     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 268   }
 269 }
 270 
 271 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 272   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 273 }
 274 
 275 // Forwards to resolve_instance_class_or_null
 276 
 277 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 278                                                      Handle class_loader,
 279                                                      Handle protection_domain,
 280                                                      TRAPS) {
 281   assert(FieldType::is_array(class_name), "must be array");
 282   Klass* k = NULL;
 283   FieldArrayInfo fd;
 284   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 285   // of this call
 286   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 287   if (t == T_OBJECT) {
 288     // naked oop "k" is OK here -- we assign back into it
 289     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 290                                                          class_loader,
 291                                                          protection_domain,
 292                                                          CHECK_NULL);
 293     if (k != NULL) {
 294       k = k->array_klass(fd.dimension(), CHECK_NULL);
 295     }
 296   } else {
 297     k = Universe::typeArrayKlassObj(t);
 298     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 299   }
 300   return k;
 301 }
 302 
 303 
 304 // Must be called for any super-class or super-interface resolution
 305 // during class definition to allow class circularity checking
 306 // super-interface callers:
 307 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 308 // super-class callers:
 309 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 310 //   load_shared_class - while loading a class from shared archive
 311 //   resolve_instance_class_or_null:
 312 //     via: handle_parallel_super_load
 313 //      when resolving a class that has an existing placeholder with
 314 //      a saved superclass [i.e. a defineClass is currently in progress]
 315 //      if another thread is trying to resolve the class, it must do
 316 //      super-class checks on its own thread to catch class circularity
 317 // This last call is critical in class circularity checking for cases
 318 // where classloading is delegated to different threads and the
 319 // classloader lock is released.
 320 // Take the case: Base->Super->Base
 321 //   1. If thread T1 tries to do a defineClass of class Base
 322 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 323 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 324 //    so it tries to load Super
 325 //   3. If we load the class internally, or user classloader uses same thread
 326 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 327 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 328 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 329 //      3.4 calls resolve_super_or_fail Base
 330 //      3.5 finds T1,Base -> throws class circularity
 331 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 332 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 333 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 334 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 335 //      4.4 finds T2, Super -> throws class circularity
 336 // Must be called, even if superclass is null, since this is
 337 // where the placeholder entry is created which claims this
 338 // thread is loading this class/classloader.
 339 // Be careful when modifying this code: once you have run
 340 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 341 // you need to find_and_remove it before returning.
 342 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 343 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 344                                                        Symbol* super_name,
 345                                                        Handle class_loader,
 346                                                        Handle protection_domain,
 347                                                        bool is_superclass,
 348                                                        TRAPS) {
 349   assert(!FieldType::is_array(super_name), "invalid super class name");
 350 #if INCLUDE_CDS
 351   if (DumpSharedSpaces) {
 352     // Special processing for handling UNREGISTERED shared classes.
 353     InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 354         super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 355     if (k) {
 356       return k;
 357     }
 358   }
 359 #endif // INCLUDE_CDS
 360 
 361   // Double-check, if child class is already loaded, just return super-class,interface
 362   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 363   // dictionary.
 364   // Make sure there's a placeholder for the *child* before resolving.
 365   // Used as a claim that this thread is currently loading superclass/classloader
 366   // Used here for ClassCircularity checks and also for heap verification
 367   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 368   // Must check ClassCircularity before checking if super class is already loaded.
 369   //
 370   // We might not already have a placeholder if this child_name was
 371   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 372   // the name of the class might not be known until the stream is actually
 373   // parsed.
 374   // Bugs 4643874, 4715493
 375 
 376   ClassLoaderData* loader_data = class_loader_data(class_loader);
 377   Dictionary* dictionary = loader_data->dictionary();
 378   unsigned int d_hash = dictionary->compute_hash(child_name);
 379   unsigned int p_hash = placeholders()->compute_hash(child_name);
 380   int p_index = placeholders()->hash_to_index(p_hash);
 381   // can't throw error holding a lock
 382   bool child_already_loaded = false;
 383   bool throw_circularity_error = false;
 384   {
 385     MutexLocker mu(SystemDictionary_lock, THREAD);
 386     InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
 387     InstanceKlass* quicksuperk;
 388     // to support // loading: if child done loading, just return superclass
 389     // if super_name, & class_loader don't match:
 390     // if initial define, SD update will give LinkageError
 391     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 392     // so we don't throw an exception here.
 393     // see: nsk redefclass014 & java.lang.instrument Instrument032
 394     if ((childk != NULL ) && (is_superclass) &&
 395         ((quicksuperk = childk->java_super()) != NULL) &&
 396          ((quicksuperk->name() == super_name) &&
 397             (oopDesc::equals(quicksuperk->class_loader(), class_loader())))) {
 398            return quicksuperk;
 399     } else {
 400       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 401       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 402           throw_circularity_error = true;
 403       }
 404     }
 405     if (!throw_circularity_error) {
 406       // Be careful not to exit resolve_super
 407       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD);
 408     }
 409   }
 410   if (throw_circularity_error) {
 411       ResourceMark rm(THREAD);
 412       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 413   }
 414 
 415 // java.lang.Object should have been found above
 416   assert(super_name != NULL, "null super class for resolving");
 417   // Resolve the super class or interface, check results on return
 418   InstanceKlass* superk =
 419     SystemDictionary::resolve_instance_class_or_null_helper(super_name,
 420                                                             class_loader,
 421                                                             protection_domain,
 422                                                             THREAD);
 423 
 424   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 425   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 426   // or error. GC used to walk the placeholder table as strong roots.
 427   // The instanceKlass is kept alive because the class loader is on the stack,
 428   // which keeps the loader_data alive, as well as all instanceKlasses in
 429   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 430   {
 431     MutexLocker mu(SystemDictionary_lock, THREAD);
 432     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 433     SystemDictionary_lock->notify_all();
 434   }
 435   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 436     // can null superk
 437     Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
 438     assert(k == NULL || k == superk, "must be");
 439     if (k == NULL) {
 440       superk = NULL;
 441     }
 442   }
 443 
 444   return superk;
 445 }
 446 
 447 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 448                                                   Handle class_loader,
 449                                                   Handle protection_domain,
 450                                                   TRAPS) {
 451   if(!has_checkPackageAccess()) return;
 452 
 453   // Now we have to call back to java to check if the initating class has access
 454   JavaValue result(T_VOID);
 455   LogTarget(Debug, protectiondomain) lt;
 456   if (lt.is_enabled()) {
 457     ResourceMark rm;
 458     // Print out trace information
 459     LogStream ls(lt);
 460     ls.print_cr("Checking package access");
 461     if (class_loader() != NULL) {
 462       ls.print("class loader: ");
 463       class_loader()->print_value_on(&ls);
 464     } else {
 465       ls.print_cr("class loader: NULL");
 466     }
 467     if (protection_domain() != NULL) {
 468       ls.print(" protection domain: ");
 469       protection_domain()->print_value_on(&ls);
 470     } else {
 471       ls.print_cr(" protection domain: NULL");
 472     }
 473     ls.print(" loading: "); klass->print_value_on(&ls);
 474     ls.cr();
 475   }
 476 
 477   // This handle and the class_loader handle passed in keeps this class from
 478   // being unloaded through several GC points.
 479   // The class_loader handle passed in is the initiating loader.
 480   Handle mirror(THREAD, klass->java_mirror());
 481 
 482   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 483   JavaCalls::call_special(&result,
 484                          class_loader,
 485                          system_loader,
 486                          vmSymbols::checkPackageAccess_name(),
 487                          vmSymbols::class_protectiondomain_signature(),
 488                          mirror,
 489                          protection_domain,
 490                          THREAD);
 491 
 492   if (HAS_PENDING_EXCEPTION) {
 493     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 494   } else {
 495    log_debug(protectiondomain)("granted");
 496   }
 497 
 498   if (HAS_PENDING_EXCEPTION) return;
 499 
 500   // If no exception has been thrown, we have validated the protection domain
 501   // Insert the protection domain of the initiating class into the set.
 502   {
 503     ClassLoaderData* loader_data = class_loader_data(class_loader);
 504     Dictionary* dictionary = loader_data->dictionary();
 505 
 506     Symbol*  kn = klass->name();
 507     unsigned int d_hash = dictionary->compute_hash(kn);
 508 
 509     MutexLocker mu(SystemDictionary_lock, THREAD);
 510     int d_index = dictionary->hash_to_index(d_hash);
 511     dictionary->add_protection_domain(d_index, d_hash, klass,
 512                                       protection_domain, THREAD);
 513   }
 514 }
 515 
 516 // We only get here if this thread finds that another thread
 517 // has already claimed the placeholder token for the current operation,
 518 // but that other thread either never owned or gave up the
 519 // object lock
 520 // Waits on SystemDictionary_lock to indicate placeholder table updated
 521 // On return, caller must recheck placeholder table state
 522 //
 523 // We only get here if
 524 //  1) custom classLoader, i.e. not bootstrap classloader
 525 //  2) custom classLoader has broken the class loader objectLock
 526 //     so another thread got here in parallel
 527 //
 528 // lockObject must be held.
 529 // Complicated dance due to lock ordering:
 530 // Must first release the classloader object lock to
 531 // allow initial definer to complete the class definition
 532 // and to avoid deadlock
 533 // Reclaim classloader lock object with same original recursion count
 534 // Must release SystemDictionary_lock after notify, since
 535 // class loader lock must be claimed before SystemDictionary_lock
 536 // to prevent deadlocks
 537 //
 538 // The notify allows applications that did an untimed wait() on
 539 // the classloader object lock to not hang.
 540 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 541   assert_lock_strong(SystemDictionary_lock);
 542 
 543   bool calledholdinglock
 544       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 545   assert(calledholdinglock,"must hold lock for notify");
 546   assert((!oopDesc::equals(lockObject(), _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 547   ObjectSynchronizer::notifyall(lockObject, THREAD);
 548   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 549   SystemDictionary_lock->wait();
 550   SystemDictionary_lock->unlock();
 551   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 552   SystemDictionary_lock->lock();
 553 }
 554 
 555 // If the class in is in the placeholder table, class loading is in progress
 556 // For cases where the application changes threads to load classes, it
 557 // is critical to ClassCircularity detection that we try loading
 558 // the superclass on the same thread internally, so we do parallel
 559 // super class loading here.
 560 // This also is critical in cases where the original thread gets stalled
 561 // even in non-circularity situations.
 562 // Note: must call resolve_super_or_fail even if null super -
 563 // to force placeholder entry creation for this class for circularity detection
 564 // Caller must check for pending exception
 565 // Returns non-null Klass* if other thread has completed load
 566 // and we are done,
 567 // If return null Klass* and no pending exception, the caller must load the class
 568 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 569     Symbol* name, Symbol* superclassname, Handle class_loader,
 570     Handle protection_domain, Handle lockObject, TRAPS) {
 571 
 572   ClassLoaderData* loader_data = class_loader_data(class_loader);
 573   Dictionary* dictionary = loader_data->dictionary();
 574   unsigned int d_hash = dictionary->compute_hash(name);
 575   unsigned int p_hash = placeholders()->compute_hash(name);
 576   int p_index = placeholders()->hash_to_index(p_hash);
 577 
 578   // superk is not used, resolve_super called for circularity check only
 579   // This code is reached in two situations. One if this thread
 580   // is loading the same class twice (e.g. ClassCircularity, or
 581   // java.lang.instrument).
 582   // The second is if another thread started the resolve_super first
 583   // and has not yet finished.
 584   // In both cases the original caller will clean up the placeholder
 585   // entry on error.
 586   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 587                                                           superclassname,
 588                                                           class_loader,
 589                                                           protection_domain,
 590                                                           true,
 591                                                           CHECK_NULL);
 592 
 593   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 594   // Serial class loaders and bootstrap classloader do wait for superclass loads
 595  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 596     MutexLocker mu(SystemDictionary_lock, THREAD);
 597     // Check if classloading completed while we were loading superclass or waiting
 598     return find_class(d_hash, name, dictionary);
 599   }
 600 
 601   // must loop to both handle other placeholder updates
 602   // and spurious notifications
 603   bool super_load_in_progress = true;
 604   PlaceholderEntry* placeholder;
 605   while (super_load_in_progress) {
 606     MutexLocker mu(SystemDictionary_lock, THREAD);
 607     // Check if classloading completed while we were loading superclass or waiting
 608     InstanceKlass* check = find_class(d_hash, name, dictionary);
 609     if (check != NULL) {
 610       // Klass is already loaded, so just return it
 611       return check;
 612     } else {
 613       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 614       if (placeholder && placeholder->super_load_in_progress() ){
 615         // We only get here if the application has released the
 616         // classloader lock when another thread was in the middle of loading a
 617         // superclass/superinterface for this class, and now
 618         // this thread is also trying to load this class.
 619         // To minimize surprises, the first thread that started to
 620         // load a class should be the one to complete the loading
 621         // with the classfile it initially expected.
 622         // This logic has the current thread wait once it has done
 623         // all the superclass/superinterface loading it can, until
 624         // the original thread completes the class loading or fails
 625         // If it completes we will use the resulting InstanceKlass
 626         // which we will find below in the systemDictionary.
 627         // We also get here for parallel bootstrap classloader
 628         if (class_loader.is_null()) {
 629           SystemDictionary_lock->wait();
 630         } else {
 631           double_lock_wait(lockObject, THREAD);
 632         }
 633       } else {
 634         // If not in SD and not in PH, other thread's load must have failed
 635         super_load_in_progress = false;
 636       }
 637     }
 638   }
 639   return NULL;
 640 }
 641 
 642 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
 643   assert(event != NULL, "invariant");
 644   assert(k != NULL, "invariant");
 645   assert(event->should_commit(), "invariant");
 646   event->set_loadedClass(k);
 647   event->set_definingClassLoader(k->class_loader_data());
 648   event->set_initiatingClassLoader(init_cld);
 649   event->commit();
 650 }
 651 
 652 
 653 // Be careful when modifying this code: once you have run
 654 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 655 // you need to find_and_remove it before returning.
 656 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 657 //
 658 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
 659 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 660                                                                 Handle class_loader,
 661                                                                 Handle protection_domain,
 662                                                                 TRAPS) {
 663   assert(name != NULL && !FieldType::is_array(name) &&
 664          !FieldType::is_obj(name), "invalid class name");
 665 
 666   EventClassLoad class_load_start_event;
 667 
 668   HandleMark hm(THREAD);
 669 
 670   // Fix for 4474172; see evaluation for more details
 671   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 672   ClassLoaderData* loader_data = register_loader(class_loader);
 673   Dictionary* dictionary = loader_data->dictionary();
 674   unsigned int d_hash = dictionary->compute_hash(name);
 675 
 676   // Do lookup to see if class already exist and the protection domain
 677   // has the right access
 678   // This call uses find which checks protection domain already matches
 679   // All subsequent calls use find_class, and set has_loaded_class so that
 680   // before we return a result we call out to java to check for valid protection domain
 681   // to allow returning the Klass* and add it to the pd_set if it is valid
 682   {
 683     InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
 684     if (probe != NULL) return probe;
 685   }
 686 
 687   // Non-bootstrap class loaders will call out to class loader and
 688   // define via jvm/jni_DefineClass which will acquire the
 689   // class loader object lock to protect against multiple threads
 690   // defining the class in parallel by accident.
 691   // This lock must be acquired here so the waiter will find
 692   // any successful result in the SystemDictionary and not attempt
 693   // the define.
 694   // ParallelCapable Classloaders and the bootstrap classloader
 695   // do not acquire lock here.
 696   bool DoObjectLock = true;
 697   if (is_parallelCapable(class_loader)) {
 698     DoObjectLock = false;
 699   }
 700 
 701   unsigned int p_hash = placeholders()->compute_hash(name);
 702   int p_index = placeholders()->hash_to_index(p_hash);
 703 
 704   // Class is not in SystemDictionary so we have to do loading.
 705   // Make sure we are synchronized on the class loader before we proceed
 706   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 707   check_loader_lock_contention(lockObject, THREAD);
 708   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 709 
 710   // Check again (after locking) if class already exist in SystemDictionary
 711   bool class_has_been_loaded   = false;
 712   bool super_load_in_progress  = false;
 713   bool havesupername = false;
 714   InstanceKlass* k = NULL;
 715   PlaceholderEntry* placeholder;
 716   Symbol* superclassname = NULL;
 717 
 718   assert(THREAD->can_call_java(),
 719          "can not load classes with compiler thread: class=%s, classloader=%s",
 720          name->as_C_string(),
 721          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 722   {
 723     MutexLocker mu(SystemDictionary_lock, THREAD);
 724     InstanceKlass* check = find_class(d_hash, name, dictionary);
 725     if (check != NULL) {
 726       // InstanceKlass is already loaded, so just return it
 727       class_has_been_loaded = true;
 728       k = check;
 729     } else {
 730       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 731       if (placeholder && placeholder->super_load_in_progress()) {
 732          super_load_in_progress = true;
 733          if (placeholder->havesupername() == true) {
 734            superclassname = placeholder->supername();
 735            havesupername = true;
 736          }
 737       }
 738     }
 739   }
 740 
 741   // If the class is in the placeholder table, class loading is in progress
 742   if (super_load_in_progress && havesupername==true) {
 743     k = handle_parallel_super_load(name,
 744                                    superclassname,
 745                                    class_loader,
 746                                    protection_domain,
 747                                    lockObject, THREAD);
 748     if (HAS_PENDING_EXCEPTION) {
 749       return NULL;
 750     }
 751     if (k != NULL) {
 752       class_has_been_loaded = true;
 753     }
 754   }
 755 
 756   bool throw_circularity_error = false;
 757   if (!class_has_been_loaded) {
 758     bool load_instance_added = false;
 759 
 760     // add placeholder entry to record loading instance class
 761     // Five cases:
 762     // All cases need to prevent modifying bootclasssearchpath
 763     // in parallel with a classload of same classname
 764     // Redefineclasses uses existence of the placeholder for the duration
 765     // of the class load to prevent concurrent redefinition of not completely
 766     // defined classes.
 767     // case 1. traditional classloaders that rely on the classloader object lock
 768     //   - no other need for LOAD_INSTANCE
 769     // case 2. traditional classloaders that break the classloader object lock
 770     //    as a deadlock workaround. Detection of this case requires that
 771     //    this check is done while holding the classloader object lock,
 772     //    and that lock is still held when calling classloader's loadClass.
 773     //    For these classloaders, we ensure that the first requestor
 774     //    completes the load and other requestors wait for completion.
 775     // case 3. Bootstrap classloader - don't own objectLocker
 776     //    This classloader supports parallelism at the classloader level,
 777     //    but only allows a single load of a class/classloader pair.
 778     //    No performance benefit and no deadlock issues.
 779     // case 4. parallelCapable user level classloaders - without objectLocker
 780     //    Allow parallel classloading of a class/classloader pair
 781 
 782     {
 783       MutexLocker mu(SystemDictionary_lock, THREAD);
 784       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 785         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 786         if (oldprobe) {
 787           // only need check_seen_thread once, not on each loop
 788           // 6341374 java/lang/Instrument with -Xcomp
 789           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 790             throw_circularity_error = true;
 791           } else {
 792             // case 1: traditional: should never see load_in_progress.
 793             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 794 
 795               // case 3: bootstrap classloader: prevent futile classloading,
 796               // wait on first requestor
 797               if (class_loader.is_null()) {
 798                 SystemDictionary_lock->wait();
 799               } else {
 800               // case 2: traditional with broken classloader lock. wait on first
 801               // requestor.
 802                 double_lock_wait(lockObject, THREAD);
 803               }
 804               // Check if classloading completed while we were waiting
 805               InstanceKlass* check = find_class(d_hash, name, dictionary);
 806               if (check != NULL) {
 807                 // Klass is already loaded, so just return it
 808                 k = check;
 809                 class_has_been_loaded = true;
 810               }
 811               // check if other thread failed to load and cleaned up
 812               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 813             }
 814           }
 815         }
 816       }
 817       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 818       // case 4: parallelCapable: allow competing threads to try
 819       // LOAD_INSTANCE in parallel
 820 
 821       if (!throw_circularity_error && !class_has_been_loaded) {
 822         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 823         load_instance_added = true;
 824         // For class loaders that do not acquire the classloader object lock,
 825         // if they did not catch another thread holding LOAD_INSTANCE,
 826         // need a check analogous to the acquire ObjectLocker/find_class
 827         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 828         // one final check if the load has already completed
 829         // class loaders holding the ObjectLock shouldn't find the class here
 830         InstanceKlass* check = find_class(d_hash, name, dictionary);
 831         if (check != NULL) {
 832         // Klass is already loaded, so return it after checking/adding protection domain
 833           k = check;
 834           class_has_been_loaded = true;
 835         }
 836       }
 837     }
 838 
 839     // must throw error outside of owning lock
 840     if (throw_circularity_error) {
 841       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 842       ResourceMark rm(THREAD);
 843       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 844     }
 845 
 846     if (!class_has_been_loaded) {
 847 
 848       // Do actual loading
 849       k = load_instance_class(name, class_loader, THREAD);
 850 
 851       // If everything was OK (no exceptions, no null return value), and
 852       // class_loader is NOT the defining loader, do a little more bookkeeping.
 853       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 854         !oopDesc::equals(k->class_loader(), class_loader())) {
 855 
 856         check_constraints(d_hash, k, class_loader, false, THREAD);
 857 
 858         // Need to check for a PENDING_EXCEPTION again; check_constraints
 859         // can throw but we may have to remove entry from the placeholder table below.
 860         if (!HAS_PENDING_EXCEPTION) {
 861           // Record dependency for non-parent delegation.
 862           // This recording keeps the defining class loader of the klass (k) found
 863           // from being unloaded while the initiating class loader is loaded
 864           // even if the reference to the defining class loader is dropped
 865           // before references to the initiating class loader.
 866           loader_data->record_dependency(k);
 867 
 868           { // Grabbing the Compile_lock prevents systemDictionary updates
 869             // during compilations.
 870             MutexLocker mu(Compile_lock, THREAD);
 871             update_dictionary(d_hash, p_index, p_hash,
 872               k, class_loader, THREAD);
 873           }
 874 
 875           if (JvmtiExport::should_post_class_load()) {
 876             Thread *thread = THREAD;
 877             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 878             JvmtiExport::post_class_load((JavaThread *) thread, k);
 879           }
 880         }
 881       }
 882     } // load_instance_class
 883 
 884     if (load_instance_added == true) {
 885       // clean up placeholder entries for LOAD_INSTANCE success or error
 886       // This brackets the SystemDictionary updates for both defining
 887       // and initiating loaders
 888       MutexLocker mu(SystemDictionary_lock, THREAD);
 889       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 890       SystemDictionary_lock->notify_all();
 891     }
 892   }
 893 
 894   if (HAS_PENDING_EXCEPTION || k == NULL) {
 895     return NULL;
 896   }
 897   if (class_load_start_event.should_commit()) {
 898     post_class_load_event(&class_load_start_event, k, loader_data);
 899   }
 900 #ifdef ASSERT
 901   {
 902     ClassLoaderData* loader_data = k->class_loader_data();
 903     MutexLocker mu(SystemDictionary_lock, THREAD);
 904     InstanceKlass* kk = find_class(name, loader_data);
 905     assert(kk == k, "should be present in dictionary");
 906   }
 907 #endif
 908 
 909   // return if the protection domain in NULL
 910   if (protection_domain() == NULL) return k;
 911 
 912   // Check the protection domain has the right access
 913   if (dictionary->is_valid_protection_domain(d_hash, name,
 914                                              protection_domain)) {
 915     return k;
 916   }
 917 
 918   // Verify protection domain. If it fails an exception is thrown
 919   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 920 
 921   return k;
 922 }
 923 
 924 
 925 // This routine does not lock the system dictionary.
 926 //
 927 // Since readers don't hold a lock, we must make sure that system
 928 // dictionary entries are only removed at a safepoint (when only one
 929 // thread is running), and are added to in a safe way (all links must
 930 // be updated in an MT-safe manner).
 931 //
 932 // Callers should be aware that an entry could be added just after
 933 // _dictionary->bucket(index) is read here, so the caller will not see
 934 // the new entry.
 935 
 936 Klass* SystemDictionary::find(Symbol* class_name,
 937                               Handle class_loader,
 938                               Handle protection_domain,
 939                               TRAPS) {
 940 
 941   // The result of this call should be consistent with the result
 942   // of the call to resolve_instance_class_or_null().
 943   // See evaluation 6790209 and 4474172 for more details.
 944   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 945   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 946 
 947   if (loader_data == NULL) {
 948     // If the ClassLoaderData has not been setup,
 949     // then the class loader has no entries in the dictionary.
 950     return NULL;
 951   }
 952 
 953   Dictionary* dictionary = loader_data->dictionary();
 954   unsigned int d_hash = dictionary->compute_hash(class_name);
 955   return dictionary->find(d_hash, class_name,
 956                           protection_domain);
 957 }
 958 
 959 
 960 // Look for a loaded instance or array klass by name.  Do not do any loading.
 961 // return NULL in case of error.
 962 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 963                                                       Handle class_loader,
 964                                                       Handle protection_domain,
 965                                                       TRAPS) {
 966   Klass* k = NULL;
 967   assert(class_name != NULL, "class name must be non NULL");
 968 
 969   if (FieldType::is_array(class_name)) {
 970     // The name refers to an array.  Parse the name.
 971     // dimension and object_key in FieldArrayInfo are assigned as a
 972     // side-effect of this call
 973     FieldArrayInfo fd;
 974     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 975     if (t != T_OBJECT) {
 976       k = Universe::typeArrayKlassObj(t);
 977     } else {
 978       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 979     }
 980     if (k != NULL) {
 981       k = k->array_klass_or_null(fd.dimension());
 982     }
 983   } else {
 984     k = find(class_name, class_loader, protection_domain, THREAD);
 985   }
 986   return k;
 987 }
 988 
 989 // Note: this method is much like resolve_from_stream, but
 990 // does not publish the classes via the SystemDictionary.
 991 // Handles unsafe_DefineAnonymousClass and redefineclasses
 992 // RedefinedClasses do not add to the class hierarchy
 993 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
 994                                               Handle class_loader,
 995                                               Handle protection_domain,
 996                                               ClassFileStream* st,
 997                                               const InstanceKlass* unsafe_anonymous_host,
 998                                               GrowableArray<Handle>* cp_patches,
 999                                               TRAPS) {
1000 
1001   EventClassLoad class_load_start_event;
1002 
1003   ClassLoaderData* loader_data;
1004   if (unsafe_anonymous_host != NULL) {
1005     // Create a new CLD for an unsafe anonymous class, that uses the same class loader
1006     // as the unsafe_anonymous_host
1007     guarantee(oopDesc::equals(unsafe_anonymous_host->class_loader(), class_loader()), "should be the same");
1008     loader_data = ClassLoaderData::unsafe_anonymous_class_loader_data(class_loader);
1009   } else {
1010     loader_data = ClassLoaderData::class_loader_data(class_loader());
1011   }
1012 
1013   assert(st != NULL, "invariant");
1014   assert(st->need_verify(), "invariant");
1015 
1016   // Parse stream and create a klass.
1017   // Note that we do this even though this klass might
1018   // already be present in the SystemDictionary, otherwise we would not
1019   // throw potential ClassFormatErrors.
1020 
1021   InstanceKlass* k = KlassFactory::create_from_stream(st,
1022                                                       class_name,
1023                                                       loader_data,
1024                                                       protection_domain,
1025                                                       unsafe_anonymous_host,
1026                                                       cp_patches,
1027                                                       CHECK_NULL);
1028 
1029   if (unsafe_anonymous_host != NULL && k != NULL) {
1030     // Unsafe anonymous classes must update ClassLoaderData holder (was unsafe_anonymous_host loader)
1031     // so that they can be unloaded when the mirror is no longer referenced.
1032     k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
1033 
1034     {
1035       MutexLocker mu_r(Compile_lock, THREAD);
1036 
1037       // Add to class hierarchy, initialize vtables, and do possible
1038       // deoptimizations.
1039       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1040 
1041       // But, do not add to dictionary.
1042 
1043       // compiled code dependencies need to be validated anyway
1044       notice_modification();
1045     }
1046 
1047     // Rewrite and patch constant pool here.
1048     k->link_class(CHECK_NULL);
1049     if (cp_patches != NULL) {
1050       k->constants()->patch_resolved_references(cp_patches);
1051     }
1052 
1053     // If it's anonymous, initialize it now, since nobody else will.
1054     k->eager_initialize(CHECK_NULL);
1055 
1056     // notify jvmti
1057     if (JvmtiExport::should_post_class_load()) {
1058         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1059         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1060     }
1061     if (class_load_start_event.should_commit()) {
1062       post_class_load_event(&class_load_start_event, k, loader_data);
1063     }
1064   }
1065   assert(unsafe_anonymous_host != NULL || NULL == cp_patches,
1066          "cp_patches only found with unsafe_anonymous_host");
1067 
1068   return k;
1069 }
1070 
1071 // Add a klass to the system from a stream (called by jni_DefineClass and
1072 // JVM_DefineClass).
1073 // Note: class_name can be NULL. In that case we do not know the name of
1074 // the class until we have parsed the stream.
1075 
1076 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1077                                                      Handle class_loader,
1078                                                      Handle protection_domain,
1079                                                      ClassFileStream* st,
1080                                                      TRAPS) {
1081 
1082   HandleMark hm(THREAD);
1083 
1084   // Classloaders that support parallelism, e.g. bootstrap classloader,
1085   // do not acquire lock here
1086   bool DoObjectLock = true;
1087   if (is_parallelCapable(class_loader)) {
1088     DoObjectLock = false;
1089   }
1090 
1091   ClassLoaderData* loader_data = register_loader(class_loader);
1092 
1093   // Make sure we are synchronized on the class loader before we proceed
1094   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1095   check_loader_lock_contention(lockObject, THREAD);
1096   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1097 
1098   assert(st != NULL, "invariant");
1099 
1100   // Parse the stream and create a klass.
1101   // Note that we do this even though this klass might
1102   // already be present in the SystemDictionary, otherwise we would not
1103   // throw potential ClassFormatErrors.
1104  InstanceKlass* k = NULL;
1105 
1106 #if INCLUDE_CDS
1107   if (!DumpSharedSpaces) {
1108     k = SystemDictionaryShared::lookup_from_stream(class_name,
1109                                                    class_loader,
1110                                                    protection_domain,
1111                                                    st,
1112                                                    CHECK_NULL);
1113   }
1114 #endif
1115 
1116   if (k == NULL) {
1117     if (st->buffer() == NULL) {
1118       return NULL;
1119     }
1120     k = KlassFactory::create_from_stream(st,
1121                                          class_name,
1122                                          loader_data,
1123                                          protection_domain,
1124                                          NULL, // unsafe_anonymous_host
1125                                          NULL, // cp_patches
1126                                          CHECK_NULL);
1127   }
1128 
1129   assert(k != NULL, "no klass created");
1130   Symbol* h_name = k->name();
1131   assert(class_name == NULL || class_name == h_name, "name mismatch");
1132 
1133   // Add class just loaded
1134   // If a class loader supports parallel classloading handle parallel define requests
1135   // find_or_define_instance_class may return a different InstanceKlass
1136   if (is_parallelCapable(class_loader)) {
1137     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1138     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1139       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1140       assert(defined_k != NULL, "Should have a klass if there's no exception");
1141       loader_data->add_to_deallocate_list(k);
1142       k = defined_k;
1143     }
1144   } else {
1145     define_instance_class(k, THREAD);
1146   }
1147 
1148   // If defining the class throws an exception register 'k' for cleanup.
1149   if (HAS_PENDING_EXCEPTION) {
1150     assert(k != NULL, "Must have an instance klass here!");
1151     loader_data->add_to_deallocate_list(k);
1152     return NULL;
1153   }
1154 
1155   // Make sure we have an entry in the SystemDictionary on success
1156   debug_only( {
1157     MutexLocker mu(SystemDictionary_lock, THREAD);
1158 
1159     Klass* check = find_class(h_name, k->class_loader_data());
1160     assert(check == k, "should be present in the dictionary");
1161   } );
1162 
1163   return k;
1164 }
1165 
1166 #if INCLUDE_CDS
1167 // Load a class for boot loader from the shared spaces. This also
1168 // forces the super class and all interfaces to be loaded.
1169 InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
1170                                                         TRAPS) {
1171   InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1172   if (ik != NULL && ik->is_shared_boot_class()) {
1173     return load_shared_class(ik, Handle(), Handle(), NULL, THREAD);
1174   }
1175   return NULL;
1176 }
1177 
1178 // Check if a shared class can be loaded by the specific classloader:
1179 //
1180 // NULL classloader:
1181 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1182 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1183 //     be defined in an unnamed module.
1184 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1185                                                InstanceKlass* ik,
1186                                                Handle class_loader, TRAPS) {
1187   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1188          "Cannot use sharing if java.base is patched");
1189   ResourceMark rm;
1190   int path_index = ik->shared_classpath_index();
1191   ClassLoaderData* loader_data = class_loader_data(class_loader);
1192   if (path_index < 0) {
1193     // path_index < 0 indicates that the class is intended for a custom loader
1194     // and should not be loaded by boot/platform/app loaders
1195     if (loader_data->is_builtin_class_loader_data()) {
1196       return false;
1197     } else {
1198       return true;
1199     }
1200   }
1201   SharedClassPathEntry* ent =
1202             (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1203   if (!Universe::is_module_initialized()) {
1204     assert(ent != NULL && ent->is_modules_image(),
1205            "Loading non-bootstrap classes before the module system is initialized");
1206     assert(class_loader.is_null(), "sanity");
1207     return true;
1208   }
1209   // Get the pkg_entry from the classloader
1210   TempNewSymbol pkg_name = NULL;
1211   PackageEntry* pkg_entry = NULL;
1212   ModuleEntry* mod_entry = NULL;
1213   const char* pkg_string = NULL;
1214   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1215   if (pkg_name != NULL) {
1216     pkg_string = pkg_name->as_C_string();
1217     if (loader_data != NULL) {
1218       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1219     }
1220     if (pkg_entry != NULL) {
1221       mod_entry = pkg_entry->module();
1222     }
1223   }
1224 
1225   // If the archived class is from a module that has been patched at runtime,
1226   // the class cannot be loaded from the archive.
1227   if (mod_entry != NULL && mod_entry->is_patched()) {
1228     return false;
1229   }
1230 
1231   if (class_loader.is_null()) {
1232     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1233     // The NULL classloader can load archived class originated from the
1234     // "modules" jimage and the -Xbootclasspath/a. For class from the
1235     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1236     // by the NULL classloader.
1237     if (mod_entry != NULL) {
1238       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1239       // ModuleEntry's location agrees with the archived class' origination.
1240       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1241         return true; // Module class from the "module" jimage
1242       }
1243     }
1244 
1245     // If the archived class is not from the "module" jimage, the class can be
1246     // loaded by the NULL classloader if
1247     //
1248     // 1. the class is from the unamed package
1249     // 2. or, the class is not from a module defined in the NULL classloader
1250     // 3. or, the class is from an unamed module
1251     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1252       // the class is from the -Xbootclasspath/a
1253       if (pkg_string == NULL ||
1254           pkg_entry == NULL ||
1255           pkg_entry->in_unnamed_module()) {
1256         assert(mod_entry == NULL ||
1257                mod_entry == loader_data->unnamed_module(),
1258                "the unnamed module is not defined in the classloader");
1259         return true;
1260       }
1261     }
1262     return false;
1263   } else {
1264     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1265               ik, class_loader, pkg_string, pkg_name,
1266               pkg_entry, mod_entry, CHECK_(false));
1267     return res;
1268   }
1269 }
1270 
1271 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1272                                                    Handle class_loader,
1273                                                    Handle protection_domain,
1274                                                    const ClassFileStream *cfs,
1275                                                    TRAPS) {
1276 
1277   if (ik != NULL) {
1278     Symbol* class_name = ik->name();
1279 
1280     bool visible = is_shared_class_visible(
1281                             class_name, ik, class_loader, CHECK_NULL);
1282     if (!visible) {
1283       return NULL;
1284     }
1285 
1286     // Resolve the superclass and interfaces. They must be the same
1287     // as in dump time, because the layout of <ik> depends on
1288     // the specific layout of ik->super() and ik->local_interfaces().
1289     //
1290     // If unexpected superclass or interfaces are found, we cannot
1291     // load <ik> from the shared archive.
1292 
1293     if (ik->super() != NULL) {
1294       Symbol*  cn = ik->super()->name();
1295       Klass *s = resolve_super_or_fail(class_name, cn,
1296                                        class_loader, protection_domain, true, CHECK_NULL);
1297       if (s != ik->super()) {
1298         // The dynamically resolved super class is not the same as the one we used during dump time,
1299         // so we cannot use ik.
1300         return NULL;
1301       } else {
1302         assert(s->is_shared(), "must be");
1303       }
1304     }
1305 
1306     Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1307     int num_interfaces = interfaces->length();
1308     for (int index = 0; index < num_interfaces; index++) {
1309       InstanceKlass* k = interfaces->at(index);
1310       Symbol* name  = k->name();
1311       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1312       if (k != i) {
1313         // The dynamically resolved interface class is not the same as the one we used during dump time,
1314         // so we cannot use ik.
1315         return NULL;
1316       } else {
1317         assert(i->is_shared(), "must be");
1318       }
1319     }
1320 
1321     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1322         ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1323     if (new_ik != NULL) {
1324       // The class is changed by CFLH. Return the new class. The shared class is
1325       // not used.
1326       return new_ik;
1327     }
1328 
1329     // Adjust methods to recover missing data.  They need addresses for
1330     // interpreter entry points and their default native method address
1331     // must be reset.
1332 
1333     // Updating methods must be done under a lock so multiple
1334     // threads don't update these in parallel
1335     //
1336     // Shared classes are all currently loaded by either the bootstrap or
1337     // internal parallel class loaders, so this will never cause a deadlock
1338     // on a custom class loader lock.
1339 
1340     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1341     {
1342       HandleMark hm(THREAD);
1343       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1344       check_loader_lock_contention(lockObject, THREAD);
1345       ObjectLocker ol(lockObject, THREAD, true);
1346       // prohibited package check assumes all classes loaded from archive call
1347       // restore_unshareable_info which calls ik->set_package()
1348       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1349     }
1350 
1351     ik->print_class_load_logging(loader_data, NULL, NULL);
1352 
1353     // For boot loader, ensure that GetSystemPackage knows that a class in this
1354     // package was loaded.
1355     if (class_loader.is_null()) {
1356       int path_index = ik->shared_classpath_index();
1357       ResourceMark rm;
1358       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1359     }
1360 
1361     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1362       // Only dump the classes that can be stored into CDS archive
1363       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1364         ResourceMark rm(THREAD);
1365         classlist_file->print_cr("%s", ik->name()->as_C_string());
1366         classlist_file->flush();
1367       }
1368     }
1369 
1370     // notify a class loaded from shared object
1371     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1372 
1373     ik->set_has_passed_fingerprint_check(false);
1374     if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1375       uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1376       uint64_t cds_fp = ik->get_stored_fingerprint();
1377       if (aot_fp != 0 && aot_fp == cds_fp) {
1378         // This class matches with a class saved in an AOT library
1379         ik->set_has_passed_fingerprint_check(true);
1380       } else {
1381         ResourceMark rm;
1382         log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1383       }
1384     }
1385   }
1386   return ik;
1387 }
1388 #endif // INCLUDE_CDS
1389 
1390 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1391 
1392   if (class_loader.is_null()) {
1393     ResourceMark rm;
1394     PackageEntry* pkg_entry = NULL;
1395     bool search_only_bootloader_append = false;
1396     ClassLoaderData *loader_data = class_loader_data(class_loader);
1397 
1398     // Find the package in the boot loader's package entry table.
1399     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1400     if (pkg_name != NULL) {
1401       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1402     }
1403 
1404     // Prior to attempting to load the class, enforce the boot loader's
1405     // visibility boundaries.
1406     if (!Universe::is_module_initialized()) {
1407       // During bootstrapping, prior to module initialization, any
1408       // class attempting to be loaded must be checked against the
1409       // java.base packages in the boot loader's PackageEntryTable.
1410       // No class outside of java.base is allowed to be loaded during
1411       // this bootstrapping window.
1412       if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1413         // Class is either in the unnamed package or in
1414         // a named package within the unnamed module.  Either
1415         // case is outside of java.base, do not attempt to
1416         // load the class post java.base definition.  If
1417         // java.base has not been defined, let the class load
1418         // and its package will be checked later by
1419         // ModuleEntryTable::verify_javabase_packages.
1420         if (ModuleEntryTable::javabase_defined()) {
1421           return NULL;
1422         }
1423       } else {
1424         // Check that the class' package is defined within java.base.
1425         ModuleEntry* mod_entry = pkg_entry->module();
1426         Symbol* mod_entry_name = mod_entry->name();
1427         if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1428           return NULL;
1429         }
1430       }
1431     } else {
1432       // After the module system has been initialized, check if the class'
1433       // package is in a module defined to the boot loader.
1434       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1435         // Class is either in the unnamed package, in a named package
1436         // within a module not defined to the boot loader or in a
1437         // a named package within the unnamed module.  In all cases,
1438         // limit visibility to search for the class only in the boot
1439         // loader's append path.
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 (oopDesc::equals(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) {
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 
1860 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1861 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1862   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1863     it->push(well_known_klass_addr((WKID)id));
1864   }
1865 }
1866 
1867 void SystemDictionary::methods_do(void f(Method*)) {
1868   // Walk methods in loaded classes
1869   MutexLocker ml(ClassLoaderDataGraph_lock);
1870   ClassLoaderDataGraph::methods_do(f);
1871   // Walk method handle intrinsics
1872   invoke_method_table()->methods_do(f);
1873 }
1874 
1875 // ----------------------------------------------------------------------------
1876 // Initialization
1877 
1878 void SystemDictionary::initialize(TRAPS) {
1879   // Allocate arrays
1880   _placeholders        = new PlaceholderTable(_placeholder_table_size);
1881   _number_of_modifications = 0;
1882   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1883   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1884   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1885   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1886 
1887   // Allocate private object used as system class loader lock
1888   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1889   // Initialize basic classes
1890   resolve_well_known_classes(CHECK);
1891 }
1892 
1893 // Compact table of directions on the initialization of klasses:
1894 static const short wk_init_info[] = {
1895   #define WK_KLASS_INIT_INFO(name, symbol) \
1896     ((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
1897 
1898   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1899   #undef WK_KLASS_INIT_INFO
1900   0
1901 };
1902 
1903 #ifdef ASSERT
1904 bool SystemDictionary::is_well_known_klass(Symbol* class_name) {
1905   int sid;
1906   for (int i = 0; (sid = wk_init_info[i]) != 0; i++) {
1907     Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1908     if (class_name == symbol) {
1909       return true;
1910     }
1911   }
1912   return false;
1913 }
1914 #endif
1915 
1916 bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
1917   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1918   int sid = wk_init_info[id - FIRST_WKID];
1919   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1920   InstanceKlass** klassp = &_well_known_klasses[id];
1921 
1922   if ((*klassp) == NULL) {
1923     Klass* k = resolve_or_fail(symbol, true, CHECK_0);
1924     (*klassp) = InstanceKlass::cast(k);
1925   }
1926   return ((*klassp) != NULL);
1927 }
1928 
1929 void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1930   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1931   for (int id = (int)start_id; id < (int)limit_id; id++) {
1932     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1933     resolve_wk_klass((WKID)id, CHECK);
1934   }
1935 
1936   // move the starting value forward to the limit:
1937   start_id = limit_id;
1938 }
1939 
1940 void SystemDictionary::resolve_well_known_classes(TRAPS) {
1941   assert(WK_KLASS(Object_klass) == NULL, "well-known classes should only be initialized once");
1942 
1943   // Create the ModuleEntry for java.base.  This call needs to be done here,
1944   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
1945   ClassLoader::classLoader_init2(CHECK);
1946 
1947   // Preload commonly used klasses
1948   WKID scan = FIRST_WKID;
1949   // first do Object, then String, Class
1950 #if INCLUDE_CDS
1951   if (UseSharedSpaces) {
1952     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1953 
1954     // It's unsafe to access the archived heap regions before they
1955     // are fixed up, so we must do the fixup as early as possible
1956     // before the archived java objects are accessed by functions
1957     // such as java_lang_Class::restore_archived_mirror and
1958     // ConstantPool::restore_unshareable_info (restores the archived
1959     // resolved_references array object).
1960     //
1961     // HeapShared::fixup_mapped_heap_regions() fills the empty
1962     // spaces in the archived heap regions and may use
1963     // SystemDictionary::Object_klass(), so we can do this only after
1964     // Object_klass is resolved. See the above resolve_wk_klasses_through()
1965     // call. No mirror objects are accessed/restored in the above call.
1966     // Mirrors are restored after java.lang.Class is loaded.
1967     HeapShared::fixup_mapped_heap_regions();
1968 
1969     // Initialize the constant pool for the Object_class
1970     assert(Object_klass()->is_shared(), "must be");
1971     Object_klass()->constants()->restore_unshareable_info(CHECK);
1972     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1973   } else
1974 #endif
1975   {
1976     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1977   }
1978 
1979   // Calculate offsets for String and Class classes since they are loaded and
1980   // can be used after this point.
1981   java_lang_String::compute_offsets();
1982   java_lang_Class::compute_offsets();
1983 
1984   // Fixup mirrors for classes loaded before java.lang.Class.
1985   // These calls iterate over the objects currently in the perm gen
1986   // so calling them at this point is matters (not before when there
1987   // are fewer objects and not later after there are more objects
1988   // in the perm gen.
1989   Universe::initialize_basic_type_mirrors(CHECK);
1990   Universe::fixup_mirrors(CHECK);
1991 
1992   // do a bunch more:
1993   resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1994 
1995   // Preload ref klasses and set reference types
1996   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1997   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1998 
1999   resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2000   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2001   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2002   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2003   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2004 
2005   // JSR 292 classes
2006   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2007   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2008   resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
2009   resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
2010   WKID last = WKID_LIMIT;
2011   resolve_wk_klasses_until(last, scan, CHECK);
2012 
2013   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2014   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2015   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2016   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2017   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2018   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2019   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2020   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2021   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2022   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2023 
2024   { // Compute whether we should use checkPackageAccess or NOT
2025     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2026     _has_checkPackageAccess = (method != NULL);
2027   }
2028 
2029 #ifdef ASSERT
2030   if (UseSharedSpaces) {
2031     assert(JvmtiExport::is_early_phase(),
2032            "All well known classes must be resolved in JVMTI early phase");
2033     for (int i = FIRST_WKID; i < last; i++) {
2034       InstanceKlass* k = _well_known_klasses[i];
2035       assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
2036     }
2037   }
2038 #endif
2039 }
2040 
2041 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2042 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2043 BasicType SystemDictionary::box_klass_type(Klass* k) {
2044   assert(k != NULL, "");
2045   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2046     if (_box_klasses[i] == k)
2047       return (BasicType)i;
2048   }
2049   return T_OBJECT;
2050 }
2051 
2052 // Constraints on class loaders. The details of the algorithm can be
2053 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2054 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2055 // that the dictionary needs to maintain a set of contraints that
2056 // must be satisfied by all classes in the dictionary.
2057 // if defining is true, then LinkageError if already in dictionary
2058 // if initiating loader, then ok if InstanceKlass matches existing entry
2059 
2060 void SystemDictionary::check_constraints(unsigned int d_hash,
2061                                          InstanceKlass* k,
2062                                          Handle class_loader,
2063                                          bool defining,
2064                                          TRAPS) {
2065   ResourceMark rm(THREAD);
2066   stringStream ss;
2067   bool throwException = false;
2068 
2069   {
2070     Symbol *name = k->name();
2071     ClassLoaderData *loader_data = class_loader_data(class_loader);
2072 
2073     MutexLocker mu(SystemDictionary_lock, THREAD);
2074 
2075     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2076     if (check != NULL) {
2077       // If different InstanceKlass - duplicate class definition,
2078       // else - ok, class loaded by a different thread in parallel.
2079       // We should only have found it if it was done loading and ok to use.
2080       // The dictionary only holds instance classes, placeholders
2081       // also hold array classes.
2082 
2083       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2084       if ((defining == true) || (k != check)) {
2085         throwException = true;
2086         ss.print("loader %s", loader_data->loader_name_and_id());
2087         ss.print(" attempted duplicate %s definition for %s. (%s)",
2088                  k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
2089       } else {
2090         return;
2091       }
2092     }
2093 
2094 #ifdef ASSERT
2095     Symbol* ph_check = find_placeholder(name, loader_data);
2096     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2097 #endif
2098 
2099     if (throwException == false) {
2100       if (constraints()->check_or_update(k, class_loader, name) == false) {
2101         throwException = true;
2102         ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
2103         ss.print(" wants to load %s %s.",
2104                  k->external_kind(), k->external_name());
2105         Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2106         if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
2107           ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
2108                    existing_klass->external_kind(),
2109                    existing_klass->class_loader_data()->loader_name_and_id(),
2110                    existing_klass->class_in_module_of_loader(false, true));
2111         } else {
2112           ss.print(" (%s)", k->class_in_module_of_loader(false, true));
2113         }
2114       }
2115     }
2116   }
2117 
2118   // Throw error now if needed (cannot throw while holding
2119   // SystemDictionary_lock because of rank ordering)
2120   if (throwException == true) {
2121     THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2122   }
2123 }
2124 
2125 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2126 // have been called.
2127 void SystemDictionary::update_dictionary(unsigned int d_hash,
2128                                          int p_index, unsigned int p_hash,
2129                                          InstanceKlass* k,
2130                                          Handle class_loader,
2131                                          TRAPS) {
2132   // Compile_lock prevents systemDictionary updates during compilations
2133   assert_locked_or_safepoint(Compile_lock);
2134   Symbol*  name  = k->name();
2135   ClassLoaderData *loader_data = class_loader_data(class_loader);
2136 
2137   {
2138     MutexLocker mu1(SystemDictionary_lock, THREAD);
2139 
2140     // See whether biased locking is enabled and if so set it for this
2141     // klass.
2142     // Note that this must be done past the last potential blocking
2143     // point / safepoint. We enable biased locking lazily using a
2144     // VM_Operation to iterate the SystemDictionary and installing the
2145     // biasable mark word into each InstanceKlass's prototype header.
2146     // To avoid race conditions where we accidentally miss enabling the
2147     // optimization for one class in the process of being added to the
2148     // dictionary, we must not safepoint after the test of
2149     // BiasedLocking::enabled().
2150     if (UseBiasedLocking && BiasedLocking::enabled()) {
2151       // Set biased locking bit for all loaded classes; it will be
2152       // cleared if revocation occurs too often for this type
2153       // NOTE that we must only do this when the class is initally
2154       // defined, not each time it is referenced from a new class loader
2155       if (oopDesc::equals(k->class_loader(), class_loader())) {
2156         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2157       }
2158     }
2159 
2160     // Make a new dictionary entry.
2161     Dictionary* dictionary = loader_data->dictionary();
2162     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2163     if (sd_check == NULL) {
2164       dictionary->add_klass(d_hash, name, k);
2165 
2166       notice_modification();
2167     }
2168   #ifdef ASSERT
2169     sd_check = find_class(d_hash, name, dictionary);
2170     assert (sd_check != NULL, "should have entry in dictionary");
2171     // Note: there may be a placeholder entry: for circularity testing
2172     // or for parallel defines
2173   #endif
2174     SystemDictionary_lock->notify_all();
2175   }
2176 }
2177 
2178 
2179 // Try to find a class name using the loader constraints.  The
2180 // loader constraints might know about a class that isn't fully loaded
2181 // yet and these will be ignored.
2182 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2183                     Symbol* class_name, Handle class_loader, TRAPS) {
2184 
2185   // First see if it has been loaded directly.
2186   // Force the protection domain to be null.  (This removes protection checks.)
2187   Handle no_protection_domain;
2188   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2189                                               no_protection_domain, CHECK_NULL);
2190   if (klass != NULL)
2191     return klass;
2192 
2193   // Now look to see if it has been loaded elsewhere, and is subject to
2194   // a loader constraint that would require this loader to return the
2195   // klass that is already loaded.
2196   if (FieldType::is_array(class_name)) {
2197     // For array classes, their Klass*s are not kept in the
2198     // constraint table. The element Klass*s are.
2199     FieldArrayInfo fd;
2200     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2201     if (t != T_OBJECT) {
2202       klass = Universe::typeArrayKlassObj(t);
2203     } else {
2204       MutexLocker mu(SystemDictionary_lock, THREAD);
2205       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2206     }
2207     // If element class already loaded, allocate array klass
2208     if (klass != NULL) {
2209       klass = klass->array_klass_or_null(fd.dimension());
2210     }
2211   } else {
2212     MutexLocker mu(SystemDictionary_lock, THREAD);
2213     // Non-array classes are easy: simply check the constraint table.
2214     klass = constraints()->find_constrained_klass(class_name, class_loader);
2215   }
2216 
2217   return klass;
2218 }
2219 
2220 
2221 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2222                                              Handle class_loader1,
2223                                              Handle class_loader2,
2224                                              Thread* THREAD) {
2225   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2226   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2227 
2228   Symbol* constraint_name = NULL;
2229   // Needs to be in same scope as constraint_name in case a Symbol is created and
2230   // assigned to constraint_name.
2231   FieldArrayInfo fd;
2232   if (!FieldType::is_array(class_name)) {
2233     constraint_name = class_name;
2234   } else {
2235     // For array classes, their Klass*s are not kept in the
2236     // constraint table. The element classes are.
2237     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2238     // primitive types always pass
2239     if (t != T_OBJECT) {
2240       return true;
2241     } else {
2242       constraint_name = fd.object_key();
2243     }
2244   }
2245 
2246   Dictionary* dictionary1 = loader_data1->dictionary();
2247   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2248 
2249   Dictionary* dictionary2 = loader_data2->dictionary();
2250   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2251 
2252   {
2253     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2254     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2255     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2256     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2257                                     klass2, class_loader2);
2258   }
2259 }
2260 
2261 // Add entry to resolution error table to record the error when the first
2262 // attempt to resolve a reference to a class has failed.
2263 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2264                                             Symbol* error, Symbol* message) {
2265   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2266   int index = resolution_errors()->hash_to_index(hash);
2267   {
2268     MutexLocker ml(SystemDictionary_lock, Thread::current());
2269     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2270   }
2271 }
2272 
2273 // Delete a resolution error for RedefineClasses for a constant pool is going away
2274 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2275   resolution_errors()->delete_entry(pool);
2276 }
2277 
2278 // Lookup resolution error table. Returns error if found, otherwise NULL.
2279 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2280                                                 Symbol** message) {
2281   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2282   int index = resolution_errors()->hash_to_index(hash);
2283   {
2284     MutexLocker ml(SystemDictionary_lock, Thread::current());
2285     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2286     if (entry != NULL) {
2287       *message = entry->message();
2288       return entry->error();
2289     } else {
2290       return NULL;
2291     }
2292   }
2293 }
2294 
2295 
2296 // Signature constraints ensure that callers and callees agree about
2297 // the meaning of type names in their signatures.  This routine is the
2298 // intake for constraints.  It collects them from several places:
2299 //
2300 //  * LinkResolver::resolve_method (if check_access is true) requires
2301 //    that the resolving class (the caller) and the defining class of
2302 //    the resolved method (the callee) agree on each type in the
2303 //    method's signature.
2304 //
2305 //  * LinkResolver::resolve_interface_method performs exactly the same
2306 //    checks.
2307 //
2308 //  * LinkResolver::resolve_field requires that the constant pool
2309 //    attempting to link to a field agree with the field's defining
2310 //    class about the type of the field signature.
2311 //
2312 //  * klassVtable::initialize_vtable requires that, when a class
2313 //    overrides a vtable entry allocated by a superclass, that the
2314 //    overriding method (i.e., the callee) agree with the superclass
2315 //    on each type in the method's signature.
2316 //
2317 //  * klassItable::initialize_itable requires that, when a class fills
2318 //    in its itables, for each non-abstract method installed in an
2319 //    itable, the method (i.e., the callee) agree with the interface
2320 //    on each type in the method's signature.
2321 //
2322 // All those methods have a boolean (check_access, checkconstraints)
2323 // which turns off the checks.  This is used from specialized contexts
2324 // such as bootstrapping, dumping, and debugging.
2325 //
2326 // No direct constraint is placed between the class and its
2327 // supertypes.  Constraints are only placed along linked relations
2328 // between callers and callees.  When a method overrides or implements
2329 // an abstract method in a supertype (superclass or interface), the
2330 // constraints are placed as if the supertype were the caller to the
2331 // overriding method.  (This works well, since callers to the
2332 // supertype have already established agreement between themselves and
2333 // the supertype.)  As a result of all this, a class can disagree with
2334 // its supertype about the meaning of a type name, as long as that
2335 // class neither calls a relevant method of the supertype, nor is
2336 // called (perhaps via an override) from the supertype.
2337 //
2338 //
2339 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2340 //
2341 // Make sure all class components (including arrays) in the given
2342 // signature will be resolved to the same class in both loaders.
2343 // Returns the name of the type that failed a loader constraint check, or
2344 // NULL if no constraint failed.  No exception except OOME is thrown.
2345 // Arrays are not added to the loader constraint table, their elements are.
2346 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2347                                                Handle loader1, Handle loader2,
2348                                                bool is_method, TRAPS)  {
2349   // Nothing to do if loaders are the same.
2350   if (oopDesc::equals(loader1(), loader2())) {
2351     return NULL;
2352   }
2353 
2354   SignatureStream sig_strm(signature, is_method);
2355   while (!sig_strm.is_done()) {
2356     if (sig_strm.is_object()) {
2357       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2358       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2359         return sig;
2360       }
2361     }
2362     sig_strm.next();
2363   }
2364   return NULL;
2365 }
2366 
2367 
2368 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2369                                                             Symbol* signature,
2370                                                             TRAPS) {
2371   methodHandle empty;
2372   assert(MethodHandles::is_signature_polymorphic(iid) &&
2373          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2374          iid != vmIntrinsics::_invokeGeneric,
2375          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2376 
2377   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2378   int          index = invoke_method_table()->hash_to_index(hash);
2379   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2380   methodHandle m;
2381   if (spe == NULL || spe->method() == NULL) {
2382     spe = NULL;
2383     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2384     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2385     if (!Arguments::is_interpreter_only()) {
2386       // Generate a compiled form of the MH intrinsic.
2387       AdapterHandlerLibrary::create_native_wrapper(m);
2388       // Check if have the compiled code.
2389       if (!m->has_compiled_code()) {
2390         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2391                    "Out of space in CodeCache for method handle intrinsic", empty);
2392       }
2393     }
2394     // Now grab the lock.  We might have to throw away the new method,
2395     // if a racing thread has managed to install one at the same time.
2396     {
2397       MutexLocker ml(SystemDictionary_lock, THREAD);
2398       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2399       if (spe == NULL)
2400         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2401       if (spe->method() == NULL)
2402         spe->set_method(m());
2403     }
2404   }
2405 
2406   assert(spe != NULL && spe->method() != NULL, "");
2407   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2408          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2409          "MH intrinsic invariant");
2410   return spe->method();
2411 }
2412 
2413 // Helper for unpacking the return value from linkMethod and linkCallSite.
2414 static methodHandle unpack_method_and_appendix(Handle mname,
2415                                                Klass* accessing_klass,
2416                                                objArrayHandle appendix_box,
2417                                                Handle* appendix_result,
2418                                                TRAPS) {
2419   methodHandle empty;
2420   if (mname.not_null()) {
2421     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2422     if (m != NULL) {
2423       oop appendix = appendix_box->obj_at(0);
2424       if (TraceMethodHandles) {
2425     #ifndef PRODUCT
2426         ttyLocker ttyl;
2427         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2428         m->print();
2429         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2430         tty->cr();
2431     #endif //PRODUCT
2432       }
2433       (*appendix_result) = Handle(THREAD, appendix);
2434       // the target is stored in the cpCache and if a reference to this
2435       // MemberName is dropped we need a way to make sure the
2436       // class_loader containing this method is kept alive.
2437       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2438       this_key->record_dependency(m->method_holder());
2439       return methodHandle(THREAD, m);
2440     }
2441   }
2442   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2443   return empty;
2444 }
2445 
2446 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2447                                                           Symbol* name,
2448                                                           Symbol* signature,
2449                                                           Klass* accessing_klass,
2450                                                           Handle *appendix_result,
2451                                                           TRAPS) {
2452   methodHandle empty;
2453   assert(THREAD->can_call_java() ,"");
2454   Handle method_type =
2455     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2456 
2457   int ref_kind = JVM_REF_invokeVirtual;
2458   oop name_oop = StringTable::intern(name, CHECK_(empty));
2459   Handle name_str (THREAD, name_oop);
2460   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2461   assert(appendix_box->obj_at(0) == NULL, "");
2462 
2463   // This should not happen.  JDK code should take care of that.
2464   if (accessing_klass == NULL || method_type.is_null()) {
2465     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2466   }
2467 
2468   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2469   JavaCallArguments args;
2470   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2471   args.push_int(ref_kind);
2472   args.push_oop(Handle(THREAD, klass->java_mirror()));
2473   args.push_oop(name_str);
2474   args.push_oop(method_type);
2475   args.push_oop(appendix_box);
2476   JavaValue result(T_OBJECT);
2477   JavaCalls::call_static(&result,
2478                          SystemDictionary::MethodHandleNatives_klass(),
2479                          vmSymbols::linkMethod_name(),
2480                          vmSymbols::linkMethod_signature(),
2481                          &args, CHECK_(empty));
2482   Handle mname(THREAD, (oop) result.get_jobject());
2483   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2484 }
2485 
2486 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2487 // We must ensure that all class loaders everywhere will reach this class, for any client.
2488 // This is a safe bet for public classes in java.lang, such as Object and String.
2489 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2490 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2491 static bool is_always_visible_class(oop mirror) {
2492   Klass* klass = java_lang_Class::as_Klass(mirror);
2493   if (klass->is_objArray_klass()) {
2494     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2495   }
2496   if (klass->is_typeArray_klass()) {
2497     return true; // primitive array
2498   }
2499   assert(klass->is_instance_klass(), "%s", klass->external_name());
2500   return klass->is_public() &&
2501          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2502           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2503 }
2504 
2505 
2506 // Return the Java mirror (java.lang.Class instance) for a single-character
2507 // descriptor.  This result, when available, is the same as produced by the
2508 // heavier API point of the same name that takes a Symbol.
2509 oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
2510   return java_lang_Class::primitive_mirror(char2type(signature_char));
2511 }
2512 
2513 // Find or construct the Java mirror (java.lang.Class instance) for a
2514 // for the given field type signature, as interpreted relative to the
2515 // given class loader.  Handles primitives, void, references, arrays,
2516 // and all other reflectable types, except method types.
2517 // N.B.  Code in reflection should use this entry point.
2518 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2519                                                    Klass* accessing_klass,
2520                                                    Handle class_loader,
2521                                                    Handle protection_domain,
2522                                                    SignatureStream::FailureMode failure_mode,
2523                                                    TRAPS) {
2524   Handle empty;
2525 
2526   assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2527          "one or the other, or perhaps neither");
2528 
2529   Symbol* type = signature;
2530 
2531   // What we have here must be a valid field descriptor,
2532   // and all valid field descriptors are supported.
2533   // Produce the same java.lang.Class that reflection reports.
2534   if (type->utf8_length() == 1) {
2535 
2536     // It's a primitive.  (Void has a primitive mirror too.)
2537     char ch = type->char_at(0);
2538     assert(is_java_primitive(char2type(ch)) || ch == 'V', "");
2539     return Handle(THREAD, find_java_mirror_for_type(ch));
2540 
2541   } else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
2542 
2543     // It's a reference type.
2544     if (accessing_klass != NULL) {
2545       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2546       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2547     }
2548     Klass* constant_type_klass;
2549     if (failure_mode == SignatureStream::ReturnNull) {
2550       constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
2551                                             CHECK_(empty));
2552     } else {
2553       bool throw_error = (failure_mode == SignatureStream::NCDFError);
2554       constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
2555                                             throw_error, CHECK_(empty));
2556     }
2557     if (constant_type_klass == NULL) {
2558       return Handle();  // report failure this way
2559     }
2560     Handle mirror(THREAD, constant_type_klass->java_mirror());
2561 
2562     // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2563     if (accessing_klass != NULL) {
2564       Klass* sel_klass = constant_type_klass;
2565       bool fold_type_to_class = true;
2566       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2567                                               fold_type_to_class, CHECK_(empty));
2568     }
2569 
2570     return mirror;
2571 
2572   }
2573 
2574   // Fall through to an error.
2575   assert(false, "unsupported mirror syntax");
2576   THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2577 }
2578 
2579 
2580 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2581 // signature, as interpreted relative to the given class loader.
2582 // Because of class loader constraints, all method handle usage must be
2583 // consistent with this loader.
2584 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2585                                                  Klass* accessing_klass,
2586                                                  TRAPS) {
2587   Handle empty;
2588   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2589   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2590   int          index = invoke_method_table()->hash_to_index(hash);
2591   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2592   if (spe != NULL && spe->method_type() != NULL) {
2593     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2594     return Handle(THREAD, spe->method_type());
2595   } else if (!THREAD->can_call_java()) {
2596     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2597     return Handle();  // do not attempt from within compiler, unless it was cached
2598   }
2599 
2600   Handle class_loader, protection_domain;
2601   if (accessing_klass != NULL) {
2602     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2603     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2604   }
2605   bool can_be_cached = true;
2606   int npts = ArgumentCount(signature).size();
2607   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2608   int arg = 0;
2609   Handle rt; // the return type from the signature
2610   ResourceMark rm(THREAD);
2611   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2612     oop mirror = NULL;
2613     if (can_be_cached) {
2614       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2615       mirror = ss.as_java_mirror(Handle(), Handle(),
2616                                  SignatureStream::ReturnNull, CHECK_(empty));
2617       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2618         // Fall back to accessing_klass context.
2619         can_be_cached = false;
2620       }
2621     }
2622     if (!can_be_cached) {
2623       // Resolve, throwing a real error if it doesn't work.
2624       mirror = ss.as_java_mirror(class_loader, protection_domain,
2625                                  SignatureStream::NCDFError, CHECK_(empty));
2626     }
2627     assert(mirror != NULL, "%s", ss.as_symbol(THREAD)->as_C_string());
2628     if (ss.at_return_type())
2629       rt = Handle(THREAD, mirror);
2630     else
2631       pts->obj_at_put(arg++, mirror);
2632 
2633     // Check accessibility.
2634     if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2635       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2636       mirror = NULL;  // safety
2637       // Emulate ConstantPool::verify_constant_pool_resolve.
2638       bool fold_type_to_class = true;
2639       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2640                                               fold_type_to_class, CHECK_(empty));
2641     }
2642   }
2643   assert(arg == npts, "");
2644 
2645   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2646   JavaCallArguments args(Handle(THREAD, rt()));
2647   args.push_oop(pts);
2648   JavaValue result(T_OBJECT);
2649   JavaCalls::call_static(&result,
2650                          SystemDictionary::MethodHandleNatives_klass(),
2651                          vmSymbols::findMethodHandleType_name(),
2652                          vmSymbols::findMethodHandleType_signature(),
2653                          &args, CHECK_(empty));
2654   Handle method_type(THREAD, (oop) result.get_jobject());
2655 
2656   if (can_be_cached) {
2657     // We can cache this MethodType inside the JVM.
2658     MutexLocker ml(SystemDictionary_lock, THREAD);
2659     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2660     if (spe == NULL)
2661       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2662     if (spe->method_type() == NULL) {
2663       spe->set_method_type(method_type());
2664     }
2665   }
2666 
2667   // report back to the caller with the MethodType
2668   return method_type;
2669 }
2670 
2671 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2672                                                 Klass* accessing_klass,
2673                                                 TRAPS) {
2674   Handle empty;
2675   ResourceMark rm(THREAD);
2676   SignatureStream ss(signature, /*is_method=*/ false);
2677   if (!ss.is_done()) {
2678     Handle class_loader, protection_domain;
2679     if (accessing_klass != NULL) {
2680       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2681       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2682     }
2683     oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2684     ss.next();
2685     if (ss.is_done()) {
2686       return Handle(THREAD, mirror);
2687     }
2688   }
2689   return empty;
2690 }
2691 
2692 // Ask Java code to find or construct a method handle constant.
2693 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2694                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2695                                                      Klass* callee,
2696                                                      Symbol* name,
2697                                                      Symbol* signature,
2698                                                      TRAPS) {
2699   Handle empty;
2700   if (caller == NULL) {
2701     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2702   }
2703   Handle name_str      = java_lang_String::create_from_symbol(name,      CHECK_(empty));
2704   Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2705 
2706   // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2707   Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2708   java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2709   java_lang_invoke_MemberName::set_name (mname(), name_str());
2710   java_lang_invoke_MemberName::set_type (mname(), signature_str());
2711   java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2712 
2713   if (ref_kind == JVM_REF_invokeVirtual &&
2714       MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2715     // Skip resolution for public signature polymorphic methods such as
2716     // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2717     // They require appendix argument which MemberName resolution doesn't handle.
2718     // There's special logic on JDK side to handle them
2719     // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2720   } else {
2721     MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2722   }
2723 
2724   // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2725   Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2726 
2727   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2728   JavaCallArguments args;
2729   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2730   args.push_int(ref_kind);
2731   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2732   args.push_oop(name_str);
2733   args.push_oop(type);
2734   JavaValue result(T_OBJECT);
2735   JavaCalls::call_static(&result,
2736                          SystemDictionary::MethodHandleNatives_klass(),
2737                          vmSymbols::linkMethodHandleConstant_name(),
2738                          vmSymbols::linkMethodHandleConstant_signature(),
2739                          &args, CHECK_(empty));
2740   return Handle(THREAD, (oop) result.get_jobject());
2741 }
2742 
2743 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2744 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2745 // with linkage results being stored back into the bootstrap specifier.
2746 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2747   // Resolve the bootstrap specifier, its name, type, and static arguments
2748   bootstrap_specifier.resolve_bsm(CHECK);
2749 
2750   // This should not happen.  JDK code should take care of that.
2751   if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
2752     THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2753   }
2754 
2755   bool is_indy = bootstrap_specifier.is_method_call();
2756   objArrayHandle appendix_box;
2757   if (is_indy) {
2758     // Some method calls may require an appendix argument.  Arrange to receive it.
2759     appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK);
2760     assert(appendix_box->obj_at(0) == NULL, "");
2761   }
2762 
2763   // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, condy_index, bsm, type, info)
2764   //       indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2765   JavaCallArguments args;
2766   args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2767   args.push_int(bootstrap_specifier.bss_index());
2768   args.push_oop(bootstrap_specifier.bsm());
2769   args.push_oop(bootstrap_specifier.name_arg());
2770   args.push_oop(bootstrap_specifier.type_arg());
2771   args.push_oop(bootstrap_specifier.arg_values());
2772   if (is_indy) {
2773     args.push_oop(appendix_box);
2774   }
2775   JavaValue result(T_OBJECT);
2776   JavaCalls::call_static(&result,
2777                          SystemDictionary::MethodHandleNatives_klass(),
2778                          is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2779                          is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2780                          &args, CHECK);
2781 
2782   Handle value(THREAD, (oop) result.get_jobject());
2783   if (is_indy) {
2784     Handle appendix;
2785     methodHandle method = unpack_method_and_appendix(value,
2786                                                      bootstrap_specifier.caller(),
2787                                                      appendix_box,
2788                                                      &appendix, CHECK);
2789     bootstrap_specifier.set_resolved_method(method, appendix);
2790   } else {
2791     bootstrap_specifier.set_resolved_value(value);
2792   }
2793 
2794   // sanity check
2795   assert(bootstrap_specifier.is_resolved() ||
2796          (bootstrap_specifier.is_method_call() &&
2797           bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2798 }
2799 
2800 // Protection domain cache table handling
2801 
2802 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2803   return _pd_cache_table->get(protection_domain);
2804 }
2805 
2806 // ----------------------------------------------------------------------------
2807 
2808 void SystemDictionary::print_on(outputStream *st) {
2809   CDS_ONLY(SystemDictionaryShared::print_on(st));
2810   GCMutexLocker mu(SystemDictionary_lock);
2811 
2812   ClassLoaderDataGraph::print_dictionary(st);
2813 
2814   // Placeholders
2815   placeholders()->print_on(st);
2816   st->cr();
2817 
2818   // loader constraints - print under SD_lock
2819   constraints()->print_on(st);
2820   st->cr();
2821 
2822   _pd_cache_table->print_on(st);
2823   st->cr();
2824 }
2825 
2826 void SystemDictionary::verify() {
2827   guarantee(constraints() != NULL,
2828             "Verify of loader constraints failed");
2829   guarantee(placeholders()->number_of_entries() >= 0,
2830             "Verify of placeholders failed");
2831 
2832   GCMutexLocker mu(SystemDictionary_lock);
2833 
2834   // Verify dictionary
2835   ClassLoaderDataGraph::verify_dictionary();
2836 
2837   placeholders()->verify();
2838 
2839   // Verify constraint table
2840   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2841   constraints()->verify(placeholders());
2842 
2843   _pd_cache_table->verify();
2844 }
2845 
2846 void SystemDictionary::dump(outputStream *st, bool verbose) {
2847   assert_locked_or_safepoint(SystemDictionary_lock);
2848   if (verbose) {
2849     print_on(st);
2850   } else {
2851     CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2852     ClassLoaderDataGraph::print_dictionary_statistics(st);
2853     placeholders()->print_table_statistics(st, "Placeholder Table");
2854     constraints()->print_table_statistics(st, "LoaderConstraints Table");
2855     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
2856   }
2857 }
2858 
2859 // Utility for dumping dictionaries.
2860 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2861                                  DCmdWithParser(output, heap),
2862   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2863            "BOOLEAN", false, "false") {
2864   _dcmdparser.add_dcmd_option(&_verbose);
2865 }
2866 
2867 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2868   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2869                          _verbose.value());
2870   VMThread::execute(&dumper);
2871 }
2872 
2873 int SystemDictionaryDCmd::num_arguments() {
2874   ResourceMark rm;
2875   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
2876   if (dcmd != NULL) {
2877     DCmdMark mark(dcmd);
2878     return dcmd->_dcmdparser.num_arguments();
2879   } else {
2880     return 0;
2881   }
2882 }
2883 
2884 void SystemDictionary::initialize_oop_storage() {
2885   _vm_weak_oop_storage =
2886     new OopStorage("VM Weak Oop Handles",
2887                    VMWeakAlloc_lock,
2888                    VMWeakActive_lock);
2889 }
2890 
2891 OopStorage* SystemDictionary::vm_weak_oop_storage() {
2892   assert(_vm_weak_oop_storage != NULL, "Uninitialized");
2893   return _vm_weak_oop_storage;
2894 }