1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderData.inline.hpp"
  27 #include "classfile/dictionary.hpp"
  28 #include "classfile/javaClasses.hpp"
  29 #include "classfile/loaderConstraints.hpp"
  30 #include "classfile/placeholders.hpp"
  31 #include "classfile/resolutionErrors.hpp"
  32 #include "classfile/systemDictionary.hpp"
  33 #if INCLUDE_CDS
  34 #include "classfile/sharedClassUtil.hpp"
  35 #include "classfile/systemDictionaryShared.hpp"
  36 #endif
  37 #include "classfile/vmSymbols.hpp"
  38 #include "compiler/compileBroker.hpp"
  39 #include "interpreter/bytecodeStream.hpp"
  40 #include "interpreter/interpreter.hpp"
  41 #include "jfr/jfrEvents.hpp"
  42 #include "jfr/jni/jfrUpcalls.hpp"
  43 #include "memory/filemap.hpp"
  44 #include "memory/gcLocker.hpp"
  45 #include "memory/oopFactory.hpp"
  46 #include "oops/instanceKlass.hpp"
  47 #include "oops/instanceRefKlass.hpp"
  48 #include "oops/klass.inline.hpp"
  49 #include "oops/methodData.hpp"
  50 #include "oops/objArrayKlass.hpp"
  51 #include "oops/oop.inline.hpp"
  52 #include "oops/oop.inline2.hpp"
  53 #include "oops/typeArrayKlass.hpp"
  54 #include "prims/jvmtiEnvBase.hpp"
  55 #include "prims/methodHandles.hpp"
  56 #include "runtime/arguments.hpp"
  57 #include "runtime/biasedLocking.hpp"
  58 #include "runtime/fieldType.hpp"
  59 #include "runtime/handles.inline.hpp"
  60 #include "runtime/java.hpp"
  61 #include "runtime/javaCalls.hpp"
  62 #include "runtime/mutexLocker.hpp"
  63 #include "runtime/orderAccess.inline.hpp"
  64 #include "runtime/signature.hpp"
  65 #include "services/classLoadingService.hpp"
  66 #include "services/threadService.hpp"
  67 #include "utilities/macros.hpp"
  68 #include "utilities/ticks.hpp"
  69 
  70 Dictionary*            SystemDictionary::_dictionary          = NULL;
  71 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  72 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;
  73 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  74 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  75 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
  76 
  77 
  78 int         SystemDictionary::_number_of_modifications = 0;
  79 int         SystemDictionary::_sdgeneration               = 0;
  80 const int   SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
  81               20201,40423,99991};
  82 
  83 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
  84 
  85 Klass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
  86                                                           =  { NULL /*, NULL...*/ };
  87 
  88 Klass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
  89 
  90 oop         SystemDictionary::_java_system_loader         =  NULL;
  91 
  92 bool        SystemDictionary::_has_loadClassInternal      =  false;
  93 bool        SystemDictionary::_has_checkPackageAccess     =  false;
  94 
  95 // lazily initialized klass variables
  96 Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
  97 
  98 #if INCLUDE_JFR
  99 static const Symbol* jfr_event_handler_proxy = NULL;
 100 #endif // INCLUDE_JFR
 101 
 102 // ----------------------------------------------------------------------------
 103 // Java-level SystemLoader
 104 
 105 oop SystemDictionary::java_system_loader() {
 106   return _java_system_loader;
 107 }
 108 
 109 void SystemDictionary::compute_java_system_loader(TRAPS) {
 110   KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
 111   JavaValue result(T_OBJECT);
 112   JavaCalls::call_static(&result,
 113                          KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
 114                          vmSymbols::getSystemClassLoader_name(),
 115                          vmSymbols::void_classloader_signature(),
 116                          CHECK);
 117 
 118   _java_system_loader = (oop)result.get_jobject();
 119 
 120   CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
 121 }
 122 
 123 
 124 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
 125   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 126   return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
 127 }
 128 
 129 // ----------------------------------------------------------------------------
 130 // debugging
 131 
 132 #ifdef ASSERT
 133 
 134 // return true if class_name contains no '.' (internal format is '/')
 135 bool SystemDictionary::is_internal_format(Symbol* class_name) {
 136   if (class_name != NULL) {
 137     ResourceMark rm;
 138     char* name = class_name->as_C_string();
 139     return strchr(name, '.') == NULL;
 140   } else {
 141     return true;
 142   }
 143 }
 144 
 145 #endif
 146 #if INCLUDE_JFR
 147 #include "jfr/jfr.hpp"
 148 #endif
 149 
 150 // ----------------------------------------------------------------------------
 151 // Parallel class loading check
 152 
 153 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 154   if (UnsyncloadClass || class_loader.is_null()) return true;
 155   if (AlwaysLockClassLoader) return false;
 156   return java_lang_ClassLoader::parallelCapable(class_loader());
 157 }
 158 // ----------------------------------------------------------------------------
 159 // ParallelDefineClass flag does not apply to bootclass loader
 160 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 161    if (class_loader.is_null()) return false;
 162    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 163      return true;
 164    }
 165    return false;
 166 }
 167 
 168 /**
 169  * Returns true if the passed class loader is the extension class loader.
 170  */
 171 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
 172   if (class_loader.is_null()) {
 173     return false;
 174   }
 175   return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
 176 }
 177 
 178 // ----------------------------------------------------------------------------
 179 // Resolving of classes
 180 
 181 // Forwards to resolve_or_null
 182 
 183 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 184   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 185   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 186     KlassHandle k_h(THREAD, klass);
 187     // can return a null klass
 188     klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD);
 189   }
 190   return klass;
 191 }
 192 
 193 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 194                                                      bool throw_error,
 195                                                      KlassHandle klass_h, TRAPS) {
 196   if (HAS_PENDING_EXCEPTION) {
 197     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 198     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 199     // and if so convert it to a NoClassDefFoundError
 200     // And chain the original ClassNotFoundException
 201     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 202       ResourceMark rm(THREAD);
 203       assert(klass_h() == NULL, "Should not have result with exception pending");
 204       Handle e(THREAD, PENDING_EXCEPTION);
 205       CLEAR_PENDING_EXCEPTION;
 206       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 207     } else {
 208       return NULL;
 209     }
 210   }
 211   // Class not found, throw appropriate error or exception depending on value of throw_error
 212   if (klass_h() == NULL) {
 213     ResourceMark rm(THREAD);
 214     if (throw_error) {
 215       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 216     } else {
 217       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 218     }
 219   }
 220   return (Klass*)klass_h();
 221 }
 222 
 223 
 224 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 225                                            bool throw_error, TRAPS)
 226 {
 227   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 228 }
 229 
 230 
 231 // Forwards to resolve_instance_class_or_null
 232 
 233 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 234   assert(!THREAD->is_Compiler_thread(),
 235          err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
 236                  class_name->as_C_string(),
 237                  class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
 238   if (FieldType::is_array(class_name)) {
 239     return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
 240   } else if (FieldType::is_obj(class_name)) {
 241     ResourceMark rm(THREAD);
 242     // Ignore wrapping L and ;.
 243     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 244                                    class_name->utf8_length() - 2, CHECK_NULL);
 245     return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
 246   } else {
 247     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
 248   }
 249 }
 250 
 251 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 252   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 253 }
 254 
 255 // Forwards to resolve_instance_class_or_null
 256 
 257 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 258                                                        Handle class_loader,
 259                                                        Handle protection_domain,
 260                                                        TRAPS) {
 261   assert(FieldType::is_array(class_name), "must be array");
 262   Klass* k = NULL;
 263   FieldArrayInfo fd;
 264   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 265   // of this call
 266   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 267   if (t == T_OBJECT) {
 268     // naked oop "k" is OK here -- we assign back into it
 269     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 270                                                          class_loader,
 271                                                          protection_domain,
 272                                                          CHECK_NULL);
 273     if (k != NULL) {
 274       k = k->array_klass(fd.dimension(), CHECK_NULL);
 275     }
 276   } else {
 277     k = Universe::typeArrayKlassObj(t);
 278     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 279   }
 280   return k;
 281 }
 282 
 283 
 284 // Must be called for any super-class or super-interface resolution
 285 // during class definition to allow class circularity checking
 286 // super-interface callers:
 287 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 288 // super-class callers:
 289 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 290 //   load_shared_class - while loading a class from shared archive
 291 //   resolve_instance_class_or_null:
 292 //     via: handle_parallel_super_load
 293 //      when resolving a class that has an existing placeholder with
 294 //      a saved superclass [i.e. a defineClass is currently in progress]
 295 //      if another thread is trying to resolve the class, it must do
 296 //      super-class checks on its own thread to catch class circularity
 297 // This last call is critical in class circularity checking for cases
 298 // where classloading is delegated to different threads and the
 299 // classloader lock is released.
 300 // Take the case: Base->Super->Base
 301 //   1. If thread T1 tries to do a defineClass of class Base
 302 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 303 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 304 //    so it tries to load Super
 305 //   3. If we load the class internally, or user classloader uses same thread
 306 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 307 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 308 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 309 //      3.4 calls resolve_super_or_fail Base
 310 //      3.5 finds T1,Base -> throws class circularity
 311 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 312 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 313 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 314 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 315 //      4.4 finds T2, Super -> throws class circularity
 316 // Must be called, even if superclass is null, since this is
 317 // where the placeholder entry is created which claims this
 318 // thread is loading this class/classloader.
 319 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 320                                                  Symbol* class_name,
 321                                                  Handle class_loader,
 322                                                  Handle protection_domain,
 323                                                  bool is_superclass,
 324                                                  TRAPS) {
 325   // Double-check, if child class is already loaded, just return super-class,interface
 326   // Don't add a placedholder if already loaded, i.e. already in system dictionary
 327   // Make sure there's a placeholder for the *child* before resolving.
 328   // Used as a claim that this thread is currently loading superclass/classloader
 329   // Used here for ClassCircularity checks and also for heap verification
 330   // (every InstanceKlass in the heap needs to be in the system dictionary
 331   // or have a placeholder).
 332   // Must check ClassCircularity before checking if super class is already loaded
 333   //
 334   // We might not already have a placeholder if this child_name was
 335   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 336   // the name of the class might not be known until the stream is actually
 337   // parsed.
 338   // Bugs 4643874, 4715493
 339   // compute_hash can have a safepoint
 340 
 341   ClassLoaderData* loader_data = class_loader_data(class_loader);
 342   unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
 343   int d_index = dictionary()->hash_to_index(d_hash);
 344   unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
 345   int p_index = placeholders()->hash_to_index(p_hash);
 346   // can't throw error holding a lock
 347   bool child_already_loaded = false;
 348   bool throw_circularity_error = false;
 349   {
 350     MutexLocker mu(SystemDictionary_lock, THREAD);
 351     Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
 352     Klass* quicksuperk;
 353     // to support // loading: if child done loading, just return superclass
 354     // if class_name, & class_loader don't match:
 355     // if initial define, SD update will give LinkageError
 356     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 357     // so we don't throw an exception here.
 358     // see: nsk redefclass014 & java.lang.instrument Instrument032
 359     if ((childk != NULL ) && (is_superclass) &&
 360        ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&
 361 
 362          ((quicksuperk->name() == class_name) &&
 363             (quicksuperk->class_loader()  == class_loader()))) {
 364            return quicksuperk;
 365     } else {
 366       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 367       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 368           throw_circularity_error = true;
 369       }
 370     }
 371     if (!throw_circularity_error) {
 372       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 373     }
 374   }
 375   if (throw_circularity_error) {
 376       ResourceMark rm(THREAD);
 377       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 378   }
 379 
 380 // java.lang.Object should have been found above
 381   assert(class_name != NULL, "null super class for resolving");
 382   // Resolve the super class or interface, check results on return
 383   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 384                                                  class_loader,
 385                                                  protection_domain,
 386                                                  THREAD);
 387 
 388   KlassHandle superk_h(THREAD, superk);
 389 
 390   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 391   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 392   // or error. GC used to walk the placeholder table as strong roots.
 393   // The instanceKlass is kept alive because the class loader is on the stack,
 394   // which keeps the loader_data alive, as well as all instanceKlasses in
 395   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 396   {
 397     MutexLocker mu(SystemDictionary_lock, THREAD);
 398     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 399     SystemDictionary_lock->notify_all();
 400   }
 401   if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
 402     // can null superk
 403     superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD));
 404   }
 405 
 406   return superk_h();
 407 }
 408 
 409 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
 410                                                   Handle class_loader,
 411                                                   Handle protection_domain,
 412                                                   TRAPS) {
 413   if(!has_checkPackageAccess()) return;
 414 
 415   // Now we have to call back to java to check if the initating class has access
 416   JavaValue result(T_VOID);
 417   if (TraceProtectionDomainVerification) {
 418     // Print out trace information
 419     tty->print_cr("Checking package access");
 420     tty->print(" - class loader:      "); class_loader()->print_value_on(tty);      tty->cr();
 421     tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
 422     tty->print(" - loading:           "); klass()->print_value_on(tty);             tty->cr();
 423   }
 424 
 425   KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
 426   JavaCalls::call_special(&result,
 427                          class_loader,
 428                          system_loader,
 429                          vmSymbols::checkPackageAccess_name(),
 430                          vmSymbols::class_protectiondomain_signature(),
 431                          Handle(THREAD, klass->java_mirror()),
 432                          protection_domain,
 433                          THREAD);
 434 
 435   if (TraceProtectionDomainVerification) {
 436     if (HAS_PENDING_EXCEPTION) {
 437       tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
 438     } else {
 439      tty->print_cr(" -> granted");
 440     }
 441     tty->cr();
 442   }
 443 
 444   if (HAS_PENDING_EXCEPTION) return;
 445 
 446   // If no exception has been thrown, we have validated the protection domain
 447   // Insert the protection domain of the initiating class into the set.
 448   {
 449     // We recalculate the entry here -- we've called out to java since
 450     // the last time it was calculated.
 451     ClassLoaderData* loader_data = class_loader_data(class_loader);
 452 
 453     Symbol*  kn = klass->name();
 454     unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
 455     int d_index = dictionary()->hash_to_index(d_hash);
 456 
 457     MutexLocker mu(SystemDictionary_lock, THREAD);
 458     {
 459       // Note that we have an entry, and entries can be deleted only during GC,
 460       // so we cannot allow GC to occur while we're holding this entry.
 461 
 462       // We're using a No_Safepoint_Verifier to catch any place where we
 463       // might potentially do a GC at all.
 464       // Dictionary::do_unloading() asserts that classes in SD are only
 465       // unloaded at a safepoint. Anonymous classes are not in SD.
 466       No_Safepoint_Verifier nosafepoint;
 467       dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
 468                                           protection_domain, THREAD);
 469     }
 470   }
 471 }
 472 
 473 // We only get here if this thread finds that another thread
 474 // has already claimed the placeholder token for the current operation,
 475 // but that other thread either never owned or gave up the
 476 // object lock
 477 // Waits on SystemDictionary_lock to indicate placeholder table updated
 478 // On return, caller must recheck placeholder table state
 479 //
 480 // We only get here if
 481 //  1) custom classLoader, i.e. not bootstrap classloader
 482 //  2) UnsyncloadClass not set
 483 //  3) custom classLoader has broken the class loader objectLock
 484 //     so another thread got here in parallel
 485 //
 486 // lockObject must be held.
 487 // Complicated dance due to lock ordering:
 488 // Must first release the classloader object lock to
 489 // allow initial definer to complete the class definition
 490 // and to avoid deadlock
 491 // Reclaim classloader lock object with same original recursion count
 492 // Must release SystemDictionary_lock after notify, since
 493 // class loader lock must be claimed before SystemDictionary_lock
 494 // to prevent deadlocks
 495 //
 496 // The notify allows applications that did an untimed wait() on
 497 // the classloader object lock to not hang.
 498 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 499   assert_lock_strong(SystemDictionary_lock);
 500 
 501   bool calledholdinglock
 502       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 503   assert(calledholdinglock,"must hold lock for notify");
 504   assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 505   ObjectSynchronizer::notifyall(lockObject, THREAD);
 506   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 507   SystemDictionary_lock->wait();
 508   SystemDictionary_lock->unlock();
 509   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 510   SystemDictionary_lock->lock();
 511 }
 512 
 513 // If the class in is in the placeholder table, class loading is in progress
 514 // For cases where the application changes threads to load classes, it
 515 // is critical to ClassCircularity detection that we try loading
 516 // the superclass on the same thread internally, so we do parallel
 517 // super class loading here.
 518 // This also is critical in cases where the original thread gets stalled
 519 // even in non-circularity situations.
 520 // Note: must call resolve_super_or_fail even if null super -
 521 // to force placeholder entry creation for this class for circularity detection
 522 // Caller must check for pending exception
 523 // Returns non-null Klass* if other thread has completed load
 524 // and we are done,
 525 // If return null Klass* and no pending exception, the caller must load the class
 526 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
 527     Symbol* name, Symbol* superclassname, Handle class_loader,
 528     Handle protection_domain, Handle lockObject, TRAPS) {
 529 
 530   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
 531   ClassLoaderData* loader_data = class_loader_data(class_loader);
 532   unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
 533   int d_index = dictionary()->hash_to_index(d_hash);
 534   unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
 535   int p_index = placeholders()->hash_to_index(p_hash);
 536 
 537   // superk is not used, resolve_super called for circularity check only
 538   // This code is reached in two situations. One if this thread
 539   // is loading the same class twice (e.g. ClassCircularity, or
 540   // java.lang.instrument).
 541   // The second is if another thread started the resolve_super first
 542   // and has not yet finished.
 543   // In both cases the original caller will clean up the placeholder
 544   // entry on error.
 545   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 546                                                           superclassname,
 547                                                           class_loader,
 548                                                           protection_domain,
 549                                                           true,
 550                                                           CHECK_(nh));
 551 
 552   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 553   // Serial class loaders and bootstrap classloader do wait for superclass loads
 554  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 555     MutexLocker mu(SystemDictionary_lock, THREAD);
 556     // Check if classloading completed while we were loading superclass or waiting
 557     Klass* check = find_class(d_index, d_hash, name, loader_data);
 558     if (check != NULL) {
 559       // Klass is already loaded, so just return it
 560       return(instanceKlassHandle(THREAD, check));
 561     } else {
 562       return nh;
 563     }
 564   }
 565 
 566   // must loop to both handle other placeholder updates
 567   // and spurious notifications
 568   bool super_load_in_progress = true;
 569   PlaceholderEntry* placeholder;
 570   while (super_load_in_progress) {
 571     MutexLocker mu(SystemDictionary_lock, THREAD);
 572     // Check if classloading completed while we were loading superclass or waiting
 573     Klass* check = find_class(d_index, d_hash, name, loader_data);
 574     if (check != NULL) {
 575       // Klass is already loaded, so just return it
 576       return(instanceKlassHandle(THREAD, check));
 577     } else {
 578       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 579       if (placeholder && placeholder->super_load_in_progress() ){
 580         // Before UnsyncloadClass:
 581         // We only get here if the application has released the
 582         // classloader lock when another thread was in the middle of loading a
 583         // superclass/superinterface for this class, and now
 584         // this thread is also trying to load this class.
 585         // To minimize surprises, the first thread that started to
 586         // load a class should be the one to complete the loading
 587         // with the classfile it initially expected.
 588         // This logic has the current thread wait once it has done
 589         // all the superclass/superinterface loading it can, until
 590         // the original thread completes the class loading or fails
 591         // If it completes we will use the resulting InstanceKlass
 592         // which we will find below in the systemDictionary.
 593         // We also get here for parallel bootstrap classloader
 594         if (class_loader.is_null()) {
 595           SystemDictionary_lock->wait();
 596         } else {
 597           double_lock_wait(lockObject, THREAD);
 598         }
 599       } else {
 600         // If not in SD and not in PH, other thread's load must have failed
 601         super_load_in_progress = false;
 602       }
 603     }
 604   }
 605   return (nh);
 606 }
 607 
 608 // utility function for class load event
 609 static void post_class_load_event(EventClassLoad &event,
 610                                   instanceKlassHandle k,
 611                                   Handle initiating_loader) {
 612 #if INCLUDE_JFR
 613   if (event.should_commit()) {
 614     event.set_loadedClass(k());
 615     event.set_definingClassLoader(k->class_loader_data());
 616     oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
 617     event.set_initiatingClassLoader(class_loader != NULL ?
 618                                     ClassLoaderData::class_loader_data_or_null(class_loader) :
 619                                     (ClassLoaderData*)NULL);
 620     event.commit();
 621   }
 622 #endif
 623 }
 624 
 625 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 626                                                         Handle class_loader,
 627                                                         Handle protection_domain,
 628                                                         TRAPS) {
 629   assert(name != NULL && !FieldType::is_array(name) &&
 630          !FieldType::is_obj(name), "invalid class name");
 631 
 632   EventClassLoad class_load_start_event;
 633 
 634   // UseNewReflection
 635   // Fix for 4474172; see evaluation for more details
 636   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 637   ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
 638 
 639   // Do lookup to see if class already exist and the protection domain
 640   // has the right access
 641   // This call uses find which checks protection domain already matches
 642   // All subsequent calls use find_class, and set has_loaded_class so that
 643   // before we return a result we call out to java to check for valid protection domain
 644   // to allow returning the Klass* and add it to the pd_set if it is valid
 645   unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
 646   int d_index = dictionary()->hash_to_index(d_hash);
 647   Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
 648                                       protection_domain, THREAD);
 649   if (probe != NULL) return probe;
 650 
 651 
 652   // Non-bootstrap class loaders will call out to class loader and
 653   // define via jvm/jni_DefineClass which will acquire the
 654   // class loader object lock to protect against multiple threads
 655   // defining the class in parallel by accident.
 656   // This lock must be acquired here so the waiter will find
 657   // any successful result in the SystemDictionary and not attempt
 658   // the define
 659   // ParallelCapable Classloaders and the bootstrap classloader,
 660   // or all classloaders with UnsyncloadClass do not acquire lock here
 661   bool DoObjectLock = true;
 662   if (is_parallelCapable(class_loader)) {
 663     DoObjectLock = false;
 664   }
 665 
 666   unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
 667   int p_index = placeholders()->hash_to_index(p_hash);
 668 
 669   // Class is not in SystemDictionary so we have to do loading.
 670   // Make sure we are synchronized on the class loader before we proceed
 671   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 672   check_loader_lock_contention(lockObject, THREAD);
 673   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 674 
 675   // Check again (after locking) if class already exist in SystemDictionary
 676   bool class_has_been_loaded   = false;
 677   bool super_load_in_progress  = false;
 678   bool havesupername = false;
 679   instanceKlassHandle k;
 680   PlaceholderEntry* placeholder;
 681   Symbol* superclassname = NULL;
 682 
 683   {
 684     MutexLocker mu(SystemDictionary_lock, THREAD);
 685     Klass* check = find_class(d_index, d_hash, name, loader_data);
 686     if (check != NULL) {
 687       // Klass is already loaded, so just return it
 688       class_has_been_loaded = true;
 689       k = instanceKlassHandle(THREAD, check);
 690     } else {
 691       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 692       if (placeholder && placeholder->super_load_in_progress()) {
 693          super_load_in_progress = true;
 694          if (placeholder->havesupername() == true) {
 695            superclassname = placeholder->supername();
 696            havesupername = true;
 697          }
 698       }
 699     }
 700   }
 701 
 702   // If the class is in the placeholder table, class loading is in progress
 703   if (super_load_in_progress && havesupername==true) {
 704     k = SystemDictionary::handle_parallel_super_load(name, superclassname,
 705         class_loader, protection_domain, lockObject, THREAD);
 706     if (HAS_PENDING_EXCEPTION) {
 707       return NULL;
 708     }
 709     if (!k.is_null()) {
 710       class_has_been_loaded = true;
 711     }
 712   }
 713 
 714   bool throw_circularity_error = false;
 715   if (!class_has_been_loaded) {
 716     bool load_instance_added = false;
 717 
 718     // add placeholder entry to record loading instance class
 719     // Five cases:
 720     // All cases need to prevent modifying bootclasssearchpath
 721     // in parallel with a classload of same classname
 722     // Redefineclasses uses existence of the placeholder for the duration
 723     // of the class load to prevent concurrent redefinition of not completely
 724     // defined classes.
 725     // case 1. traditional classloaders that rely on the classloader object lock
 726     //   - no other need for LOAD_INSTANCE
 727     // case 2. traditional classloaders that break the classloader object lock
 728     //    as a deadlock workaround. Detection of this case requires that
 729     //    this check is done while holding the classloader object lock,
 730     //    and that lock is still held when calling classloader's loadClass.
 731     //    For these classloaders, we ensure that the first requestor
 732     //    completes the load and other requestors wait for completion.
 733     // case 3. UnsyncloadClass - don't use objectLocker
 734     //    With this flag, we allow parallel classloading of a
 735     //    class/classloader pair
 736     // case4. Bootstrap classloader - don't own objectLocker
 737     //    This classloader supports parallelism at the classloader level,
 738     //    but only allows a single load of a class/classloader pair.
 739     //    No performance benefit and no deadlock issues.
 740     // case 5. parallelCapable user level classloaders - without objectLocker
 741     //    Allow parallel classloading of a class/classloader pair
 742 
 743     {
 744       MutexLocker mu(SystemDictionary_lock, THREAD);
 745       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 746         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 747         if (oldprobe) {
 748           // only need check_seen_thread once, not on each loop
 749           // 6341374 java/lang/Instrument with -Xcomp
 750           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 751             throw_circularity_error = true;
 752           } else {
 753             // case 1: traditional: should never see load_in_progress.
 754             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 755 
 756               // case 4: bootstrap classloader: prevent futile classloading,
 757               // wait on first requestor
 758               if (class_loader.is_null()) {
 759                 SystemDictionary_lock->wait();
 760               } else {
 761               // case 2: traditional with broken classloader lock. wait on first
 762               // requestor.
 763                 double_lock_wait(lockObject, THREAD);
 764               }
 765               // Check if classloading completed while we were waiting
 766               Klass* check = find_class(d_index, d_hash, name, loader_data);
 767               if (check != NULL) {
 768                 // Klass is already loaded, so just return it
 769                 k = instanceKlassHandle(THREAD, check);
 770                 class_has_been_loaded = true;
 771               }
 772               // check if other thread failed to load and cleaned up
 773               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 774             }
 775           }
 776         }
 777       }
 778       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 779       // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
 780       // LOAD_INSTANCE in parallel
 781 
 782       if (!throw_circularity_error && !class_has_been_loaded) {
 783         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 784         load_instance_added = true;
 785         // For class loaders that do not acquire the classloader object lock,
 786         // if they did not catch another thread holding LOAD_INSTANCE,
 787         // need a check analogous to the acquire ObjectLocker/find_class
 788         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 789         // one final check if the load has already completed
 790         // class loaders holding the ObjectLock shouldn't find the class here
 791         Klass* check = find_class(d_index, d_hash, name, loader_data);
 792         if (check != NULL) {
 793         // Klass is already loaded, so return it after checking/adding protection domain
 794           k = instanceKlassHandle(THREAD, check);
 795           class_has_been_loaded = true;
 796         }
 797       }
 798     }
 799 
 800     // must throw error outside of owning lock
 801     if (throw_circularity_error) {
 802       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 803       ResourceMark rm(THREAD);
 804       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 805     }
 806 
 807     if (!class_has_been_loaded) {
 808 
 809       // Do actual loading
 810       k = load_instance_class(name, class_loader, THREAD);
 811 
 812       // For UnsyncloadClass only
 813       // If they got a linkageError, check if a parallel class load succeeded.
 814       // If it did, then for bytecode resolution the specification requires
 815       // that we return the same result we did for the other thread, i.e. the
 816       // successfully loaded InstanceKlass
 817       // Should not get here for classloaders that support parallelism
 818       // with the new cleaner mechanism, even with AllowParallelDefineClass
 819       // Bootstrap goes through here to allow for an extra guarantee check
 820       if (UnsyncloadClass || (class_loader.is_null())) {
 821         if (k.is_null() && HAS_PENDING_EXCEPTION
 822           && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
 823           MutexLocker mu(SystemDictionary_lock, THREAD);
 824           Klass* check = find_class(d_index, d_hash, name, loader_data);
 825           if (check != NULL) {
 826             // Klass is already loaded, so just use it
 827             k = instanceKlassHandle(THREAD, check);
 828             CLEAR_PENDING_EXCEPTION;
 829             guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
 830           }
 831         }
 832       }
 833 
 834       // If everything was OK (no exceptions, no null return value), and
 835       // class_loader is NOT the defining loader, do a little more bookkeeping.
 836       if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
 837         k->class_loader() != class_loader()) {
 838 
 839         check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
 840 
 841         // Need to check for a PENDING_EXCEPTION again; check_constraints
 842         // can throw but we may have to remove entry from the placeholder table below.
 843         if (!HAS_PENDING_EXCEPTION) {
 844           // Record dependency for non-parent delegation.
 845           // This recording keeps the defining class loader of the klass (k) found
 846           // from being unloaded while the initiating class loader is loaded
 847           // even if the reference to the defining class loader is dropped
 848           // before references to the initiating class loader.
 849           loader_data->record_dependency(k(), THREAD);
 850         }
 851 
 852         if (!HAS_PENDING_EXCEPTION) {
 853           { // Grabbing the Compile_lock prevents systemDictionary updates
 854             // during compilations.
 855             MutexLocker mu(Compile_lock, THREAD);
 856             update_dictionary(d_index, d_hash, p_index, p_hash,
 857                               k, class_loader, THREAD);
 858           }
 859 
 860           if (JvmtiExport::should_post_class_load()) {
 861             Thread *thread = THREAD;
 862             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 863             JvmtiExport::post_class_load((JavaThread *) thread, k());
 864           }
 865         }
 866       }
 867     } // load_instance_class loop
 868 
 869     if (load_instance_added == true) {
 870       // clean up placeholder entries for LOAD_INSTANCE success or error
 871       // This brackets the SystemDictionary updates for both defining
 872       // and initiating loaders
 873       MutexLocker mu(SystemDictionary_lock, THREAD);
 874       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 875       SystemDictionary_lock->notify_all();
 876     }
 877   }
 878 
 879   if (HAS_PENDING_EXCEPTION || k.is_null()) {
 880     return NULL;
 881   }
 882 
 883   post_class_load_event(class_load_start_event, k, class_loader);
 884 
 885 #ifdef ASSERT
 886   {
 887     ClassLoaderData* loader_data = k->class_loader_data();
 888     MutexLocker mu(SystemDictionary_lock, THREAD);
 889     Klass* kk = find_class(name, loader_data);
 890     assert(kk == k(), "should be present in dictionary");
 891   }
 892 #endif
 893 
 894   // return if the protection domain in NULL
 895   if (protection_domain() == NULL) return k();
 896 
 897   // Check the protection domain has the right access
 898   {
 899     MutexLocker mu(SystemDictionary_lock, THREAD);
 900     // Note that we have an entry, and entries can be deleted only during GC,
 901     // so we cannot allow GC to occur while we're holding this entry.
 902     // We're using a No_Safepoint_Verifier to catch any place where we
 903     // might potentially do a GC at all.
 904     // Dictionary::do_unloading() asserts that classes in SD are only
 905     // unloaded at a safepoint. Anonymous classes are not in SD.
 906     No_Safepoint_Verifier nosafepoint;
 907     if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
 908                                                  loader_data,
 909                                                  protection_domain)) {
 910       return k();
 911     }
 912   }
 913 
 914   // Verify protection domain. If it fails an exception is thrown
 915   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 916 
 917   return k();
 918 }
 919 
 920 
 921 // This routine does not lock the system dictionary.
 922 //
 923 // Since readers don't hold a lock, we must make sure that system
 924 // dictionary entries are only removed at a safepoint (when only one
 925 // thread is running), and are added to in a safe way (all links must
 926 // be updated in an MT-safe manner).
 927 //
 928 // Callers should be aware that an entry could be added just after
 929 // _dictionary->bucket(index) is read here, so the caller will not see
 930 // the new entry.
 931 
 932 Klass* SystemDictionary::find(Symbol* class_name,
 933                               Handle class_loader,
 934                               Handle protection_domain,
 935                               TRAPS) {
 936 
 937   // UseNewReflection
 938   // The result of this call should be consistent with the result
 939   // of the call to resolve_instance_class_or_null().
 940   // See evaluation 6790209 and 4474172 for more details.
 941   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 942   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 943 
 944   if (loader_data == NULL) {
 945     // If the ClassLoaderData has not been setup,
 946     // then the class loader has no entries in the dictionary.
 947     return NULL;
 948   }
 949 
 950   unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
 951   int d_index = dictionary()->hash_to_index(d_hash);
 952 
 953   {
 954     // Note that we have an entry, and entries can be deleted only during GC,
 955     // so we cannot allow GC to occur while we're holding this entry.
 956     // We're using a No_Safepoint_Verifier to catch any place where we
 957     // might potentially do a GC at all.
 958     // Dictionary::do_unloading() asserts that classes in SD are only
 959     // unloaded at a safepoint. Anonymous classes are not in SD.
 960     No_Safepoint_Verifier nosafepoint;
 961     return dictionary()->find(d_index, d_hash, class_name, loader_data,
 962                               protection_domain, THREAD);
 963   }
 964 }
 965 
 966 
 967 // Look for a loaded instance or array klass by name.  Do not do any loading.
 968 // return NULL in case of error.
 969 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 970                                                       Handle class_loader,
 971                                                       Handle protection_domain,
 972                                                       TRAPS) {
 973   Klass* k = NULL;
 974   assert(class_name != NULL, "class name must be non NULL");
 975 
 976   if (FieldType::is_array(class_name)) {
 977     // The name refers to an array.  Parse the name.
 978     // dimension and object_key in FieldArrayInfo are assigned as a
 979     // side-effect of this call
 980     FieldArrayInfo fd;
 981     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 982     if (t != T_OBJECT) {
 983       k = Universe::typeArrayKlassObj(t);
 984     } else {
 985       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 986     }
 987     if (k != NULL) {
 988       k = k->array_klass_or_null(fd.dimension());
 989     }
 990   } else {
 991     k = find(class_name, class_loader, protection_domain, THREAD);
 992   }
 993   return k;
 994 }
 995 
 996 // Note: this method is much like resolve_from_stream, but
 997 // updates no supplemental data structures.
 998 // TODO consolidate the two methods with a helper routine?
 999 Klass* SystemDictionary::parse_stream(Symbol* class_name,
1000                                       Handle class_loader,
1001                                       Handle protection_domain,
1002                                       ClassFileStream* st,
1003                                       KlassHandle host_klass,
1004                                       GrowableArray<Handle>* cp_patches,
1005                                       TRAPS) {
1006   TempNewSymbol parsed_name = NULL;
1007 
1008   EventClassLoad class_load_start_event;
1009 
1010   ClassLoaderData* loader_data;
1011   if (host_klass.not_null()) {
1012     // Create a new CLD for anonymous class, that uses the same class loader
1013     // as the host_klass
1014     assert(EnableInvokeDynamic, "");
1015     guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1016     guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
1017     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1018     loader_data->record_dependency(host_klass(), CHECK_NULL);
1019   } else {
1020     loader_data = ClassLoaderData::class_loader_data(class_loader());
1021   }
1022 
1023   // Parse the stream. Note that we do this even though this klass might
1024   // already be present in the SystemDictionary, otherwise we would not
1025   // throw potential ClassFormatErrors.
1026   //
1027   // Note: "name" is updated.
1028 
1029   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1030                                                              loader_data,
1031                                                              protection_domain,
1032                                                              host_klass,
1033                                                              cp_patches,
1034                                                              parsed_name,
1035                                                              true,
1036                                                              THREAD);
1037 
1038 
1039   if (host_klass.not_null() && k.not_null()) {
1040     assert(EnableInvokeDynamic, "");
1041     // If it's anonymous, initialize it now, since nobody else will.
1042 
1043     {
1044       MutexLocker mu_r(Compile_lock, THREAD);
1045 
1046       // Add to class hierarchy, initialize vtables, and do possible
1047       // deoptimizations.
1048       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1049 
1050       // But, do not add to system dictionary.
1051 
1052       // compiled code dependencies need to be validated anyway
1053       notice_modification();
1054     }
1055 
1056     // Rewrite and patch constant pool here.
1057     k->link_class(CHECK_NULL);
1058     if (cp_patches != NULL) {
1059       k->constants()->patch_resolved_references(cp_patches);
1060     }
1061     k->eager_initialize(CHECK_NULL);
1062 
1063     // notify jvmti
1064     if (JvmtiExport::should_post_class_load()) {
1065         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1066         JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1067     }
1068 
1069     post_class_load_event(class_load_start_event, k, class_loader);
1070   }
1071   assert(host_klass.not_null() || cp_patches == NULL,
1072          "cp_patches only found with host_klass");
1073 
1074   return k();
1075 }
1076 
1077 // Add a klass to the system from a stream (called by jni_DefineClass and
1078 // JVM_DefineClass).
1079 // Note: class_name can be NULL. In that case we do not know the name of
1080 // the class until we have parsed the stream.
1081 
1082 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1083                                              Handle class_loader,
1084                                              Handle protection_domain,
1085                                              ClassFileStream* st,
1086                                              bool verify,
1087                                              TRAPS) {
1088 
1089   // Classloaders that support parallelism, e.g. bootstrap classloader,
1090   // or all classloaders with UnsyncloadClass do not acquire lock here
1091   bool DoObjectLock = true;
1092   if (is_parallelCapable(class_loader)) {
1093     DoObjectLock = false;
1094   }
1095 
1096   ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1097 
1098   // Make sure we are synchronized on the class loader before we proceed
1099   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1100   check_loader_lock_contention(lockObject, THREAD);
1101   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1102 
1103   TempNewSymbol parsed_name = NULL;
1104 
1105   // Parse the stream. Note that we do this even though this klass might
1106   // already be present in the SystemDictionary, otherwise we would not
1107   // throw potential ClassFormatErrors.
1108   //
1109   // Note: "name" is updated.
1110 
1111   ClassFileParser parser(st);
1112   instanceKlassHandle k = parser.parseClassFile(class_name,
1113                                                 loader_data,
1114                                                 protection_domain,
1115                                                 parsed_name,
1116                                                 verify,
1117                                                 THREAD);
1118 
1119   const char* pkg = "java/";
1120   size_t pkglen = strlen(pkg);
1121   if (!HAS_PENDING_EXCEPTION &&
1122       !class_loader.is_null() &&
1123       parsed_name != NULL &&
1124       parsed_name->utf8_length() >= (int)pkglen &&
1125       !strncmp((const char*)parsed_name->bytes(), pkg, pkglen)) {
1126     // It is illegal to define classes in the "java." package from
1127     // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1128     ResourceMark rm(THREAD);
1129     char* name = parsed_name->as_C_string();
1130     char* index = strrchr(name, '/');
1131     assert(index != NULL, "must be");
1132     *index = '\0'; // chop to just the package name
1133     while ((index = strchr(name, '/')) != NULL) {
1134       *index = '.'; // replace '/' with '.' in package name
1135     }
1136     const char* fmt = "Prohibited package name: %s";
1137     size_t len = strlen(fmt) + strlen(name);
1138     char* message = NEW_RESOURCE_ARRAY(char, len);
1139     jio_snprintf(message, len, fmt, name);
1140     Exceptions::_throw_msg(THREAD_AND_LOCATION,
1141       vmSymbols::java_lang_SecurityException(), message);
1142   }
1143 
1144   if (!HAS_PENDING_EXCEPTION) {
1145     assert(parsed_name != NULL, "Sanity");
1146     assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1147     // Verification prevents us from creating names with dots in them, this
1148     // asserts that that's the case.
1149     assert(is_internal_format(parsed_name),
1150            "external class name format used internally");
1151 
1152 #if INCLUDE_JFR
1153     {
1154       InstanceKlass* ik = k();
1155       ON_KLASS_CREATION(ik, parser, THREAD);
1156       k = instanceKlassHandle(ik);
1157     }
1158 #endif
1159 
1160     // Add class just loaded
1161     // If a class loader supports parallel classloading handle parallel define requests
1162     // find_or_define_instance_class may return a different InstanceKlass
1163     if (is_parallelCapable(class_loader)) {
1164       k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1165     } else {
1166       define_instance_class(k, THREAD);
1167     }
1168   }
1169 
1170   // Make sure we have an entry in the SystemDictionary on success
1171   debug_only( {
1172     if (!HAS_PENDING_EXCEPTION) {
1173       assert(parsed_name != NULL, "parsed_name is still null?");
1174       Symbol*  h_name    = k->name();
1175       ClassLoaderData *defining_loader_data = k->class_loader_data();
1176 
1177       MutexLocker mu(SystemDictionary_lock, THREAD);
1178 
1179       Klass* check = find_class(parsed_name, loader_data);
1180       assert(check == k(), "should be present in the dictionary");
1181 
1182       Klass* check2 = find_class(h_name, defining_loader_data);
1183       assert(check == check2, "name inconsistancy in SystemDictionary");
1184     }
1185   } );
1186 
1187   return k();
1188 }
1189 
1190 #if INCLUDE_CDS
1191 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1192                                              int number_of_entries) {
1193   assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1194          "bad shared dictionary size.");
1195   _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1196 }
1197 
1198 
1199 // If there is a shared dictionary, then find the entry for the
1200 // given shared system class, if any.
1201 
1202 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1203   if (shared_dictionary() != NULL) {
1204     unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1205     int d_index = shared_dictionary()->hash_to_index(d_hash);
1206 
1207     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1208   } else {
1209     return NULL;
1210   }
1211 }
1212 
1213 
1214 // Load a class from the shared spaces (found through the shared system
1215 // dictionary).  Force the superclass and all interfaces to be loaded.
1216 // Update the class definition to include sibling classes and no
1217 // subclasses (yet).  [Classes in the shared space are not part of the
1218 // object hierarchy until loaded.]
1219 
1220 instanceKlassHandle SystemDictionary::load_shared_class(
1221                  Symbol* class_name, Handle class_loader, TRAPS) {
1222   instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1223   // Make sure we only return the boot class for the NULL classloader.
1224   if (ik.not_null() &&
1225       SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1226     Handle protection_domain;
1227     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1228   }
1229   return instanceKlassHandle();
1230 }
1231 
1232 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1233                                                         Handle class_loader,
1234                                                         Handle protection_domain, TRAPS) {
1235   if (ik.not_null()) {
1236     instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1237     Symbol* class_name = ik->name();
1238 
1239     // Found the class, now load the superclass and interfaces.  If they
1240     // are shared, add them to the main system dictionary and reset
1241     // their hierarchy references (supers, subs, and interfaces).
1242 
1243     if (ik->super() != NULL) {
1244       Symbol*  cn = ik->super()->name();
1245       Klass *s = resolve_super_or_fail(class_name, cn,
1246                                        class_loader, protection_domain, true, CHECK_(nh));
1247       if (s != ik->super()) {
1248         // The dynamically resolved super class is not the same as the one we used during dump time,
1249         // so we cannot use ik.
1250         return nh;
1251       }
1252     }
1253 
1254     Array<Klass*>* interfaces = ik->local_interfaces();
1255     int num_interfaces = interfaces->length();
1256     for (int index = 0; index < num_interfaces; index++) {
1257       Klass* k = interfaces->at(index);
1258 
1259       // Note: can not use InstanceKlass::cast here because
1260       // interfaces' InstanceKlass's C++ vtbls haven't been
1261       // reinitialized yet (they will be once the interface classes
1262       // are loaded)
1263       Symbol*  name  = k->name();
1264       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1265       if (k != i) {
1266         // The dynamically resolved interface class is not the same as the one we used during dump time,
1267         // so we cannot use ik.
1268         return nh;
1269       }
1270     }
1271 
1272     // Adjust methods to recover missing data.  They need addresses for
1273     // interpreter entry points and their default native method address
1274     // must be reset.
1275 
1276     // Updating methods must be done under a lock so multiple
1277     // threads don't update these in parallel
1278     //
1279     // Shared classes are all currently loaded by either the bootstrap or
1280     // internal parallel class loaders, so this will never cause a deadlock
1281     // on a custom class loader lock.
1282 
1283     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1284     {
1285       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1286       check_loader_lock_contention(lockObject, THREAD);
1287       ObjectLocker ol(lockObject, THREAD, true);
1288       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1289     }
1290 
1291     if (TraceClassLoading) {
1292       ResourceMark rm;
1293       tty->print("[Loaded %s", ik->external_name());
1294       tty->print(" from shared objects file");
1295       if (class_loader.not_null()) {
1296         tty->print(" by %s", loader_data->loader_name());
1297       }
1298       tty->print_cr("]");
1299     }
1300 
1301     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1302       // Only dump the classes that can be stored into CDS archive
1303       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1304         ResourceMark rm(THREAD);
1305         classlist_file->print_cr("%s", ik->name()->as_C_string());
1306         classlist_file->flush();
1307       }
1308     }
1309 
1310     // notify a class loaded from shared object
1311     ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
1312                                              true /* shared class */);
1313   }
1314   return ik;
1315 }
1316 #endif // INCLUDE_CDS
1317 
1318 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1319   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1320   if (class_loader.is_null()) {
1321 
1322     // Search the shared system dictionary for classes preloaded into the
1323     // shared spaces.
1324     instanceKlassHandle k;
1325     {
1326 #if INCLUDE_CDS
1327       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1328       k = load_shared_class(class_name, class_loader, THREAD);
1329 #endif
1330     }
1331 
1332     if (k.is_null()) {
1333       // Use VM class loader
1334       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1335       k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1336     }
1337 
1338     // find_or_define_instance_class may return a different InstanceKlass
1339     if (!k.is_null()) {
1340       k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1341     }
1342 
1343 #if INCLUDE_JFR
1344     if (k.is_null() && (class_name == jfr_event_handler_proxy)) {
1345       assert(jfr_event_handler_proxy != NULL, "invariant");
1346       // EventHandlerProxy class is generated dynamically in
1347       // EventHandlerProxyCreator::makeEventHandlerProxyClass
1348       // method, so we generate a Java call from here.
1349       //
1350       // EventHandlerProxy class will finally be defined in
1351       // SystemDictionary::resolve_from_stream method, down
1352       // the call stack. Bootstrap classloader is parallel-capable,
1353       // so no concurrency issues are expected.
1354       CLEAR_PENDING_EXCEPTION;
1355       k = JfrUpcalls::load_event_handler_proxy_class(THREAD);
1356       assert(!k.is_null(), "invariant");
1357     }
1358 #endif
1359 
1360     return k;
1361   } else {
1362     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1363     ResourceMark rm(THREAD);
1364 
1365     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1366     JavaThread* jt = (JavaThread*) THREAD;
1367 
1368     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1369                                ClassLoader::perf_app_classload_selftime(),
1370                                ClassLoader::perf_app_classload_count(),
1371                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1372                                jt->get_thread_stat()->perf_timers_addr(),
1373                                PerfClassTraceTime::CLASS_LOAD);
1374 
1375     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1376     // Translate to external class name format, i.e., convert '/' chars to '.'
1377     Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1378 
1379     JavaValue result(T_OBJECT);
1380 
1381     KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1382 
1383     // Call public unsynchronized loadClass(String) directly for all class loaders
1384     // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1385     // acquire a class-name based lock rather than the class loader object lock.
1386     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1387     // so the call to loadClassInternal() was not required.
1388     //
1389     // UnsyncloadClass flag means both call loadClass(String) and do
1390     // not acquire the class loader lock even for class loaders that are
1391     // not parallelCapable. This was a risky transitional
1392     // flag for diagnostic purposes only. It is risky to call
1393     // custom class loaders without synchronization.
1394     // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1395     // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1396     // Do NOT assume this will be supported in future releases.
1397     //
1398     // Added MustCallLoadClassInternal in case we discover in the field
1399     // a customer that counts on this call
1400     if (MustCallLoadClassInternal && has_loadClassInternal()) {
1401       JavaCalls::call_special(&result,
1402                               class_loader,
1403                               spec_klass,
1404                               vmSymbols::loadClassInternal_name(),
1405                               vmSymbols::string_class_signature(),
1406                               string,
1407                               CHECK_(nh));
1408     } else {
1409       JavaCalls::call_virtual(&result,
1410                               class_loader,
1411                               spec_klass,
1412                               vmSymbols::loadClass_name(),
1413                               vmSymbols::string_class_signature(),
1414                               string,
1415                               CHECK_(nh));
1416     }
1417 
1418     assert(result.get_type() == T_OBJECT, "just checking");
1419     oop obj = (oop) result.get_jobject();
1420 
1421     // Primitive classes return null since forName() can not be
1422     // used to obtain any of the Class objects representing primitives or void
1423     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1424       instanceKlassHandle k =
1425                 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1426       // For user defined Java class loaders, check that the name returned is
1427       // the same as that requested.  This check is done for the bootstrap
1428       // loader when parsing the class file.
1429       if (class_name == k->name()) {
1430         return k;
1431       }
1432     }
1433     // Class is not found or has the wrong name, return NULL
1434     return nh;
1435   }
1436 }
1437 
1438 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1439   EventClassDefine event;
1440   if (event.should_commit()) {
1441     event.set_definedClass(k);
1442     event.set_definingClassLoader(def_cld);
1443     event.commit();
1444   }
1445 }
1446 
1447 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1448 
1449   ClassLoaderData* loader_data = k->class_loader_data();
1450   Handle class_loader_h(THREAD, loader_data->class_loader());
1451 
1452   for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
1453 
1454  // for bootstrap and other parallel classloaders don't acquire lock,
1455  // use placeholder token
1456  // If a parallelCapable class loader calls define_instance_class instead of
1457  // find_or_define_instance_class to get here, we have a timing
1458  // hole with systemDictionary updates and check_constraints
1459  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1460     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1461          compute_loader_lock_object(class_loader_h, THREAD)),
1462          "define called without lock");
1463   }
1464 
1465   // Check class-loading constraints. Throw exception if violation is detected.
1466   // Grabs and releases SystemDictionary_lock
1467   // The check_constraints/find_class call and update_dictionary sequence
1468   // must be "atomic" for a specific class/classloader pair so we never
1469   // define two different instanceKlasses for that class/classloader pair.
1470   // Existing classloaders will call define_instance_class with the
1471   // classloader lock held
1472   // Parallel classloaders will call find_or_define_instance_class
1473   // which will require a token to perform the define class
1474   Symbol*  name_h = k->name();
1475   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1476   int d_index = dictionary()->hash_to_index(d_hash);
1477   check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1478 
1479   // Register class just loaded with class loader (placed in Vector)
1480   // Note we do this before updating the dictionary, as this can
1481   // fail with an OutOfMemoryError (if it does, we will *not* put this
1482   // class in the dictionary and will not update the class hierarchy).
1483   // JVMTI FollowReferences needs to find the classes this way.
1484   if (k->class_loader() != NULL) {
1485     methodHandle m(THREAD, Universe::loader_addClass_method());
1486     JavaValue result(T_VOID);
1487     JavaCallArguments args(class_loader_h);
1488     args.push_oop(Handle(THREAD, k->java_mirror()));
1489     JavaCalls::call(&result, m, &args, CHECK);
1490   }
1491 
1492   // Add the new class. We need recompile lock during update of CHA.
1493   {
1494     unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1495     int p_index = placeholders()->hash_to_index(p_hash);
1496 
1497     MutexLocker mu_r(Compile_lock, THREAD);
1498 
1499     // Add to class hierarchy, initialize vtables, and do possible
1500     // deoptimizations.
1501     add_to_hierarchy(k, CHECK); // No exception, but can block
1502 
1503     // Add to systemDictionary - so other classes can see it.
1504     // Grabs and releases SystemDictionary_lock
1505     update_dictionary(d_index, d_hash, p_index, p_hash,
1506                       k, class_loader_h, THREAD);
1507   }
1508   k->eager_initialize(THREAD);
1509 
1510   // notify jvmti
1511   if (JvmtiExport::should_post_class_load()) {
1512       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1513       JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1514 
1515   }
1516 
1517   post_class_define_event(k(), loader_data);
1518 }
1519 
1520 // Support parallel classloading
1521 // All parallel class loaders, including bootstrap classloader
1522 // lock a placeholder entry for this class/class_loader pair
1523 // to allow parallel defines of different classes for this class loader
1524 // With AllowParallelDefine flag==true, in case they do not synchronize around
1525 // FindLoadedClass/DefineClass, calls, we check for parallel
1526 // loading for them, wait if a defineClass is in progress
1527 // and return the initial requestor's results
1528 // This flag does not apply to the bootstrap classloader.
1529 // With AllowParallelDefine flag==false, call through to define_instance_class
1530 // which will throw LinkageError: duplicate class definition.
1531 // False is the requested default.
1532 // For better performance, the class loaders should synchronize
1533 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1534 // potentially waste time reading and parsing the bytestream.
1535 // Note: VM callers should ensure consistency of k/class_name,class_loader
1536 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1537 
1538   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1539   Symbol*  name_h = k->name(); // passed in class_name may be null
1540   ClassLoaderData* loader_data = class_loader_data(class_loader);
1541 
1542   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1543   int d_index = dictionary()->hash_to_index(d_hash);
1544 
1545 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1546   unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1547   int p_index = placeholders()->hash_to_index(p_hash);
1548   PlaceholderEntry* probe;
1549 
1550   {
1551     MutexLocker mu(SystemDictionary_lock, THREAD);
1552     // First check if class already defined
1553     if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1554       Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1555       if (check != NULL) {
1556         return(instanceKlassHandle(THREAD, check));
1557       }
1558     }
1559 
1560     // Acquire define token for this class/classloader
1561     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1562     // Wait if another thread defining in parallel
1563     // All threads wait - even those that will throw duplicate class: otherwise
1564     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1565     // if other thread has not finished updating dictionary
1566     while (probe->definer() != NULL) {
1567       SystemDictionary_lock->wait();
1568     }
1569     // Only special cases allow parallel defines and can use other thread's results
1570     // Other cases fall through, and may run into duplicate defines
1571     // caught by finding an entry in the SystemDictionary
1572     if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1573         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1574         SystemDictionary_lock->notify_all();
1575 #ifdef ASSERT
1576         Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1577         assert(check != NULL, "definer missed recording success");
1578 #endif
1579         return(instanceKlassHandle(THREAD, probe->instance_klass()));
1580     } else {
1581       // This thread will define the class (even if earlier thread tried and had an error)
1582       probe->set_definer(THREAD);
1583     }
1584   }
1585 
1586   define_instance_class(k, THREAD);
1587 
1588   Handle linkage_exception = Handle(); // null handle
1589 
1590   // definer must notify any waiting threads
1591   {
1592     MutexLocker mu(SystemDictionary_lock, THREAD);
1593     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1594     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1595     if (probe != NULL) {
1596       if (HAS_PENDING_EXCEPTION) {
1597         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1598         CLEAR_PENDING_EXCEPTION;
1599       } else {
1600         probe->set_instance_klass(k());
1601       }
1602       probe->set_definer(NULL);
1603       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1604       SystemDictionary_lock->notify_all();
1605     }
1606   }
1607 
1608   // Can't throw exception while holding lock due to rank ordering
1609   if (linkage_exception() != NULL) {
1610     THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1611   }
1612 
1613   return k;
1614 }
1615 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1616   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1617   if (class_loader.is_null()) {
1618     return Handle(THREAD, _system_loader_lock_obj);
1619   } else {
1620     return class_loader;
1621   }
1622 }
1623 
1624 // This method is added to check how often we have to wait to grab loader
1625 // lock. The results are being recorded in the performance counters defined in
1626 // ClassLoader::_sync_systemLoaderLockContentionRate and
1627 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1628 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1629   if (!UsePerfData) {
1630     return;
1631   }
1632 
1633   assert(!loader_lock.is_null(), "NULL lock object");
1634 
1635   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1636       == ObjectSynchronizer::owner_other) {
1637     // contention will likely happen, so increment the corresponding
1638     // contention counter.
1639     if (loader_lock() == _system_loader_lock_obj) {
1640       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1641     } else {
1642       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1643     }
1644   }
1645 }
1646 
1647 // ----------------------------------------------------------------------------
1648 // Lookup
1649 
1650 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1651                                       Symbol* class_name,
1652                                       ClassLoaderData* loader_data) {
1653   assert_locked_or_safepoint(SystemDictionary_lock);
1654   assert (index == dictionary()->index_for(class_name, loader_data),
1655           "incorrect index?");
1656 
1657   Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1658   return k;
1659 }
1660 
1661 
1662 // Basic find on classes in the midst of being loaded
1663 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1664                                            ClassLoaderData* loader_data) {
1665   assert_locked_or_safepoint(SystemDictionary_lock);
1666   unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1667   int p_index = placeholders()->hash_to_index(p_hash);
1668   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1669 }
1670 
1671 
1672 // Used for assertions and verification only
1673 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1674   #ifndef ASSERT
1675   guarantee(VerifyBeforeGC      ||
1676             VerifyDuringGC      ||
1677             VerifyBeforeExit    ||
1678             VerifyDuringStartup ||
1679             VerifyAfterGC, "too expensive");
1680   #endif
1681   assert_locked_or_safepoint(SystemDictionary_lock);
1682 
1683   // First look in the loaded class array
1684   unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1685   int d_index = dictionary()->hash_to_index(d_hash);
1686   return find_class(d_index, d_hash, class_name, loader_data);
1687 }
1688 
1689 
1690 // Get the next class in the diictionary.
1691 Klass* SystemDictionary::try_get_next_class() {
1692   return dictionary()->try_get_next_class();
1693 }
1694 
1695 
1696 // ----------------------------------------------------------------------------
1697 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1698 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1699 // before a new class is used.
1700 
1701 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1702   assert(k.not_null(), "just checking");
1703   assert_locked_or_safepoint(Compile_lock);
1704 
1705   // Link into hierachy. Make sure the vtables are initialized before linking into
1706   k->append_to_sibling_list();                    // add to superklass/sibling list
1707   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1708   k->set_init_state(InstanceKlass::loaded);
1709   // Now flush all code that depended on old class hierarchy.
1710   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1711   // Also, first reinitialize vtable because it may have gotten out of synch
1712   // while the new class wasn't connected to the class hierarchy.
1713   Universe::flush_dependents_on(k);
1714 }
1715 
1716 // ----------------------------------------------------------------------------
1717 // GC support
1718 
1719 // Following roots during mark-sweep is separated in two phases.
1720 //
1721 // The first phase follows preloaded classes and all other system
1722 // classes, since these will never get unloaded anyway.
1723 //
1724 // The second phase removes (unloads) unreachable classes from the
1725 // system dictionary and follows the remaining classes' contents.
1726 
1727 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1728   roots_oops_do(blk, NULL);
1729 }
1730 
1731 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1732   // Follow all system classes and temporary placeholders in dictionary
1733   dictionary()->always_strong_classes_do(closure);
1734 
1735   // Placeholders. These represent classes we're actively loading.
1736   placeholders()->classes_do(closure);
1737 }
1738 
1739 // Calculate a "good" systemdictionary size based
1740 // on predicted or current loaded classes count
1741 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1742   int newsize = _old_default_sdsize;
1743   if ((classcount > 0)  && !DumpSharedSpaces) {
1744     int desiredsize = classcount/_average_depth_goal;
1745     for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1746          newsize = _primelist[++_sdgeneration]) {
1747       if (desiredsize <=  newsize) {
1748         break;
1749       }
1750     }
1751   }
1752   return newsize;
1753 }
1754 
1755 #ifdef ASSERT
1756 class VerifySDReachableAndLiveClosure : public OopClosure {
1757 private:
1758   BoolObjectClosure* _is_alive;
1759 
1760   template <class T> void do_oop_work(T* p) {
1761     oop obj = oopDesc::load_decode_heap_oop(p);
1762     guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1763   }
1764 
1765 public:
1766   VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1767 
1768   virtual void do_oop(oop* p)       { do_oop_work(p); }
1769   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1770 };
1771 #endif
1772 
1773 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1774 // Note: anonymous classes are not in the SD.
1775 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive, bool clean_alive) {
1776   // First, mark for unload all ClassLoaderData referencing a dead class loader.
1777   bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive, clean_alive);
1778   if (unloading_occurred) {
1779     JFR_ONLY(Jfr::on_unloading_classes();)
1780     dictionary()->do_unloading();
1781     constraints()->purge_loader_constraints();
1782     resolution_errors()->purge_resolution_errors();
1783   }
1784   // Oops referenced by the system dictionary may get unreachable independently
1785   // of the class loader (eg. cached protection domain oops). So we need to
1786   // explicitly unlink them here instead of in Dictionary::do_unloading.
1787   dictionary()->unlink(is_alive);
1788 #ifdef ASSERT
1789   VerifySDReachableAndLiveClosure cl(is_alive);
1790   dictionary()->oops_do(&cl);
1791 #endif
1792   return unloading_occurred;
1793 }
1794 
1795 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1796   strong->do_oop(&_java_system_loader);
1797   strong->do_oop(&_system_loader_lock_obj);
1798   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1799 
1800   // Adjust dictionary
1801   dictionary()->roots_oops_do(strong, weak);
1802 
1803   // Visit extra methods
1804   invoke_method_table()->oops_do(strong);
1805 }
1806 
1807 void SystemDictionary::oops_do(OopClosure* f) {
1808   f->do_oop(&_java_system_loader);
1809   f->do_oop(&_system_loader_lock_obj);
1810   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1811 
1812   // Adjust dictionary
1813   dictionary()->oops_do(f);
1814 
1815   // Visit extra methods
1816   invoke_method_table()->oops_do(f);
1817 }
1818 
1819 // Extended Class redefinition support.
1820 // If one of these classes is replaced, we need to replace it in these places.
1821 // KlassClosure::do_klass should take the address of a class but we can
1822 // change that later.
1823 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1824   for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1825     f->do_klass(_well_known_klasses[k]);
1826   }
1827 
1828   {
1829     for (int i = 0; i < T_VOID+1; i++) {
1830       if (_box_klasses[i] != NULL) {
1831         assert(i >= T_BOOLEAN, "checking");
1832         f->do_klass(_box_klasses[i]);
1833       }
1834     }
1835   }
1836 
1837   FilteredFieldsMap::classes_do(f);
1838 }
1839 
1840 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1841   f->do_klass(_abstract_ownable_synchronizer_klass);
1842 }
1843 
1844 // Just the classes from defining class loaders
1845 // Don't iterate over placeholders
1846 void SystemDictionary::classes_do(void f(Klass*)) {
1847   dictionary()->classes_do(f);
1848 }
1849 
1850 // Added for initialize_itable_for_klass
1851 //   Just the classes from defining class loaders
1852 // Don't iterate over placeholders
1853 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1854   dictionary()->classes_do(f, CHECK);
1855 }
1856 
1857 //   All classes, and their class loaders
1858 // Don't iterate over placeholders
1859 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1860   dictionary()->classes_do(f);
1861 }
1862 
1863 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1864   placeholders()->entries_do(f);
1865 }
1866 
1867 void SystemDictionary::methods_do(void f(Method*)) {
1868   dictionary()->methods_do(f);
1869   invoke_method_table()->methods_do(f);
1870 }
1871 
1872 void SystemDictionary::remove_classes_in_error_state() {
1873   dictionary()->remove_classes_in_error_state();
1874 }
1875 
1876 // ----------------------------------------------------------------------------
1877 // Lazily load klasses
1878 
1879 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1880   assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1881 
1882   // if multiple threads calling this function, only one thread will load
1883   // the class.  The other threads will find the loaded version once the
1884   // class is loaded.
1885   Klass* aos = _abstract_ownable_synchronizer_klass;
1886   if (aos == NULL) {
1887     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1888     // Force a fence to prevent any read before the write completes
1889     OrderAccess::fence();
1890     _abstract_ownable_synchronizer_klass = k;
1891   }
1892 }
1893 
1894 // ----------------------------------------------------------------------------
1895 // Initialization
1896 
1897 void SystemDictionary::initialize(TRAPS) {
1898   // Allocate arrays
1899   assert(dictionary() == NULL,
1900          "SystemDictionary should only be initialized once");
1901   _sdgeneration        = 0;
1902   _dictionary          = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1903   _placeholders        = new PlaceholderTable(_nof_buckets);
1904   _number_of_modifications = 0;
1905   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1906   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1907   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1908 
1909   // Allocate private object used as system class loader lock
1910   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1911   // Initialize basic classes
1912   initialize_preloaded_classes(CHECK);
1913 #if INCLUDE_JFR
1914   jfr_event_handler_proxy = SymbolTable::new_permanent_symbol("jdk/jfr/proxy/internal/EventHandlerProxy", CHECK);
1915 #endif // INCLUDE_JFR
1916 }
1917 
1918 // Compact table of directions on the initialization of klasses:
1919 static const short wk_init_info[] = {
1920   #define WK_KLASS_INIT_INFO(name, symbol, option) \
1921     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1922           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1923       | (int)SystemDictionary::option ),
1924   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1925   #undef WK_KLASS_INIT_INFO
1926   0
1927 };
1928 
1929 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1930   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1931   int  info = wk_init_info[id - FIRST_WKID];
1932   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
1933   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1934   Klass**    klassp = &_well_known_klasses[id];
1935   bool must_load = (init_opt < SystemDictionary::Opt);
1936   if ((*klassp) == NULL) {
1937     if (must_load) {
1938       (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1939     } else {
1940       (*klassp) = resolve_or_null(symbol,       CHECK_0); // load optional klass
1941     }
1942   }
1943   return ((*klassp) != NULL);
1944 }
1945 
1946 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1947   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1948   for (int id = (int)start_id; id < (int)limit_id; id++) {
1949     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1950     int info = wk_init_info[id - FIRST_WKID];
1951     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
1952     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1953 
1954     initialize_wk_klass((WKID)id, opt, CHECK);
1955   }
1956 
1957   // move the starting value forward to the limit:
1958   start_id = limit_id;
1959 }
1960 
1961 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1962   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1963   // Preload commonly used klasses
1964   WKID scan = FIRST_WKID;
1965   // first do Object, then String, Class
1966   if (UseSharedSpaces) {
1967     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1968     // Initialize the constant pool for the Object_class
1969     InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1970     ik->constants()->restore_unshareable_info(CHECK);
1971     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1972   } else {
1973     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1974   }
1975 
1976   // Calculate offsets for String and Class classes since they are loaded and
1977   // can be used after this point.
1978   java_lang_String::compute_offsets();
1979   java_lang_Class::compute_offsets();
1980 
1981   // Fixup mirrors for classes loaded before java.lang.Class.
1982   // These calls iterate over the objects currently in the perm gen
1983   // so calling them at this point is matters (not before when there
1984   // are fewer objects and not later after there are more objects
1985   // in the perm gen.
1986   Universe::initialize_basic_type_mirrors(CHECK);
1987   Universe::fixup_mirrors(CHECK);
1988 
1989   // do a bunch more:
1990   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1991 
1992   // Preload ref klasses and set reference types
1993   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1994   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1995 
1996   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
1997   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1998   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1999   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2000   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2001   InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
2002 
2003   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(ReferenceQueue_klass), scan, CHECK);
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   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
2009   if (EnableInvokeDynamic) {
2010     initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
2011   } else {
2012     // Skip the JSR 292 classes, if not enabled.
2013     scan = WKID(jsr292_group_end + 1);
2014   }
2015 
2016   initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
2017 
2018   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2019   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2020   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2021   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2022   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2023   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2024   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2025   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2026   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2027   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2028 
2029   { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2030     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2031     _has_loadClassInternal = (method != NULL);
2032   }
2033   { // Compute whether we should use checkPackageAccess or NOT
2034     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2035     _has_checkPackageAccess = (method != NULL);
2036   }
2037 }
2038 
2039 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2040 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2041 BasicType SystemDictionary::box_klass_type(Klass* k) {
2042   assert(k != NULL, "");
2043   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2044     if (_box_klasses[i] == k)
2045       return (BasicType)i;
2046   }
2047   return T_OBJECT;
2048 }
2049 
2050 // Constraints on class loaders. The details of the algorithm can be
2051 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2052 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2053 // that the system dictionary needs to maintain a set of contraints that
2054 // must be satisfied by all classes in the dictionary.
2055 // if defining is true, then LinkageError if already in systemDictionary
2056 // if initiating loader, then ok if InstanceKlass matches existing entry
2057 
2058 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2059                                          instanceKlassHandle k,
2060                                          Handle class_loader, bool defining,
2061                                          TRAPS) {
2062   const char *linkage_error = NULL;
2063   {
2064     Symbol*  name  = k->name();
2065     ClassLoaderData *loader_data = class_loader_data(class_loader);
2066 
2067     MutexLocker mu(SystemDictionary_lock, THREAD);
2068 
2069     Klass* check = find_class(d_index, d_hash, name, loader_data);
2070     if (check != (Klass*)NULL) {
2071       // if different InstanceKlass - duplicate class definition,
2072       // else - ok, class loaded by a different thread in parallel,
2073       // we should only have found it if it was done loading and ok to use
2074       // system dictionary only holds instance classes, placeholders
2075       // also holds array classes
2076 
2077       assert(check->oop_is_instance(), "noninstance in systemdictionary");
2078       if ((defining == true) || (k() != check)) {
2079         linkage_error = "loader (instance of  %s): attempted  duplicate class "
2080           "definition for name: \"%s\"";
2081       } else {
2082         return;
2083       }
2084     }
2085 
2086 #ifdef ASSERT
2087     Symbol* ph_check = find_placeholder(name, loader_data);
2088     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2089 #endif
2090 
2091     if (linkage_error == NULL) {
2092       if (constraints()->check_or_update(k, class_loader, name) == false) {
2093         linkage_error = "loader constraint violation: loader (instance of %s)"
2094           " previously initiated loading for a different type with name \"%s\"";
2095       }
2096     }
2097   }
2098 
2099   // Throw error now if needed (cannot throw while holding
2100   // SystemDictionary_lock because of rank ordering)
2101 
2102   if (linkage_error) {
2103     ResourceMark rm(THREAD);
2104     const char* class_loader_name = loader_name(class_loader());
2105     char* type_name = k->name()->as_C_string();
2106     size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
2107       strlen(type_name);
2108     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2109     jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
2110     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2111   }
2112 }
2113 
2114 
2115 // Update system dictionary - done after check_constraint and add_to_hierachy
2116 // have been called.
2117 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2118                                          int p_index, unsigned int p_hash,
2119                                          instanceKlassHandle k,
2120                                          Handle class_loader,
2121                                          TRAPS) {
2122   // Compile_lock prevents systemDictionary updates during compilations
2123   assert_locked_or_safepoint(Compile_lock);
2124   Symbol*  name  = k->name();
2125   ClassLoaderData *loader_data = class_loader_data(class_loader);
2126 
2127   {
2128   MutexLocker mu1(SystemDictionary_lock, THREAD);
2129 
2130   // See whether biased locking is enabled and if so set it for this
2131   // klass.
2132   // Note that this must be done past the last potential blocking
2133   // point / safepoint. We enable biased locking lazily using a
2134   // VM_Operation to iterate the SystemDictionary and installing the
2135   // biasable mark word into each InstanceKlass's prototype header.
2136   // To avoid race conditions where we accidentally miss enabling the
2137   // optimization for one class in the process of being added to the
2138   // dictionary, we must not safepoint after the test of
2139   // BiasedLocking::enabled().
2140   if (UseBiasedLocking && BiasedLocking::enabled()) {
2141     // Set biased locking bit for all loaded classes; it will be
2142     // cleared if revocation occurs too often for this type
2143     // NOTE that we must only do this when the class is initally
2144     // defined, not each time it is referenced from a new class loader
2145     if (k->class_loader() == class_loader()) {
2146       k->set_prototype_header(markOopDesc::biased_locking_prototype());
2147     }
2148   }
2149 
2150   // Make a new system dictionary entry.
2151   Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2152   if (sd_check == NULL) {
2153     dictionary()->add_klass(name, loader_data, k);
2154     notice_modification();
2155   }
2156 #ifdef ASSERT
2157   sd_check = find_class(d_index, d_hash, name, loader_data);
2158   assert (sd_check != NULL, "should have entry in system dictionary");
2159   // Note: there may be a placeholder entry: for circularity testing
2160   // or for parallel defines
2161 #endif
2162     SystemDictionary_lock->notify_all();
2163   }
2164 }
2165 
2166 
2167 // Try to find a class name using the loader constraints.  The
2168 // loader constraints might know about a class that isn't fully loaded
2169 // yet and these will be ignored.
2170 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2171                     Symbol* class_name, Handle class_loader, TRAPS) {
2172 
2173   // First see if it has been loaded directly.
2174   // Force the protection domain to be null.  (This removes protection checks.)
2175   Handle no_protection_domain;
2176   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2177                                               no_protection_domain, CHECK_NULL);
2178   if (klass != NULL)
2179     return klass;
2180 
2181   // Now look to see if it has been loaded elsewhere, and is subject to
2182   // a loader constraint that would require this loader to return the
2183   // klass that is already loaded.
2184   if (FieldType::is_array(class_name)) {
2185     // For array classes, their Klass*s are not kept in the
2186     // constraint table. The element Klass*s are.
2187     FieldArrayInfo fd;
2188     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2189     if (t != T_OBJECT) {
2190       klass = Universe::typeArrayKlassObj(t);
2191     } else {
2192       MutexLocker mu(SystemDictionary_lock, THREAD);
2193       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2194     }
2195     // If element class already loaded, allocate array klass
2196     if (klass != NULL) {
2197       klass = klass->array_klass_or_null(fd.dimension());
2198     }
2199   } else {
2200     MutexLocker mu(SystemDictionary_lock, THREAD);
2201     // Non-array classes are easy: simply check the constraint table.
2202     klass = constraints()->find_constrained_klass(class_name, class_loader);
2203   }
2204 
2205   return klass;
2206 }
2207 
2208 
2209 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2210                                              Handle class_loader1,
2211                                              Handle class_loader2,
2212                                              Thread* THREAD) {
2213   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2214   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2215 
2216   Symbol* constraint_name = NULL;
2217   if (!FieldType::is_array(class_name)) {
2218     constraint_name = class_name;
2219   } else {
2220     // For array classes, their Klass*s are not kept in the
2221     // constraint table. The element classes are.
2222     FieldArrayInfo fd;
2223     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2224     // primitive types always pass
2225     if (t != T_OBJECT) {
2226       return true;
2227     } else {
2228       constraint_name = fd.object_key();
2229     }
2230   }
2231   unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2232   int d_index1 = dictionary()->hash_to_index(d_hash1);
2233 
2234   unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2235   int d_index2 = dictionary()->hash_to_index(d_hash2);
2236   {
2237   MutexLocker mu_s(SystemDictionary_lock, THREAD);
2238 
2239   // Better never do a GC while we're holding these oops
2240   No_Safepoint_Verifier nosafepoint;
2241 
2242   Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2243   Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2244   return constraints()->add_entry(constraint_name, klass1, class_loader1,
2245                                   klass2, class_loader2);
2246   }
2247 }
2248 
2249 // Add entry to resolution error table to record the error when the first
2250 // attempt to resolve a reference to a class has failed.
2251 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which,
2252                                             Symbol* error, Symbol* message) {
2253   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2254   int index = resolution_errors()->hash_to_index(hash);
2255   {
2256     MutexLocker ml(SystemDictionary_lock, Thread::current());
2257     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2258   }
2259 }
2260 
2261 // Delete a resolution error for RedefineClasses for a constant pool is going away
2262 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2263   resolution_errors()->delete_entry(pool);
2264 }
2265 
2266 // Lookup resolution error table. Returns error if found, otherwise NULL.
2267 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which,
2268                                                 Symbol** message) {
2269   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2270   int index = resolution_errors()->hash_to_index(hash);
2271   {
2272     MutexLocker ml(SystemDictionary_lock, Thread::current());
2273     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2274     if (entry != NULL) {
2275       *message = entry->message();
2276       return entry->error();
2277     } else {
2278       return NULL;
2279     }
2280   }
2281 }
2282 
2283 
2284 // Signature constraints ensure that callers and callees agree about
2285 // the meaning of type names in their signatures.  This routine is the
2286 // intake for constraints.  It collects them from several places:
2287 //
2288 //  * LinkResolver::resolve_method (if check_access is true) requires
2289 //    that the resolving class (the caller) and the defining class of
2290 //    the resolved method (the callee) agree on each type in the
2291 //    method's signature.
2292 //
2293 //  * LinkResolver::resolve_interface_method performs exactly the same
2294 //    checks.
2295 //
2296 //  * LinkResolver::resolve_field requires that the constant pool
2297 //    attempting to link to a field agree with the field's defining
2298 //    class about the type of the field signature.
2299 //
2300 //  * klassVtable::initialize_vtable requires that, when a class
2301 //    overrides a vtable entry allocated by a superclass, that the
2302 //    overriding method (i.e., the callee) agree with the superclass
2303 //    on each type in the method's signature.
2304 //
2305 //  * klassItable::initialize_itable requires that, when a class fills
2306 //    in its itables, for each non-abstract method installed in an
2307 //    itable, the method (i.e., the callee) agree with the interface
2308 //    on each type in the method's signature.
2309 //
2310 // All those methods have a boolean (check_access, checkconstraints)
2311 // which turns off the checks.  This is used from specialized contexts
2312 // such as bootstrapping, dumping, and debugging.
2313 //
2314 // No direct constraint is placed between the class and its
2315 // supertypes.  Constraints are only placed along linked relations
2316 // between callers and callees.  When a method overrides or implements
2317 // an abstract method in a supertype (superclass or interface), the
2318 // constraints are placed as if the supertype were the caller to the
2319 // overriding method.  (This works well, since callers to the
2320 // supertype have already established agreement between themselves and
2321 // the supertype.)  As a result of all this, a class can disagree with
2322 // its supertype about the meaning of a type name, as long as that
2323 // class neither calls a relevant method of the supertype, nor is
2324 // called (perhaps via an override) from the supertype.
2325 //
2326 //
2327 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2328 //
2329 // Make sure all class components (including arrays) in the given
2330 // signature will be resolved to the same class in both loaders.
2331 // Returns the name of the type that failed a loader constraint check, or
2332 // NULL if no constraint failed.  No exception except OOME is thrown.
2333 // Arrays are not added to the loader constraint table, their elements are.
2334 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2335                                                Handle loader1, Handle loader2,
2336                                                bool is_method, TRAPS)  {
2337   // Nothing to do if loaders are the same.
2338   if (loader1() == loader2()) {
2339     return NULL;
2340   }
2341 
2342   SignatureStream sig_strm(signature, is_method);
2343   while (!sig_strm.is_done()) {
2344     if (sig_strm.is_object()) {
2345       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2346       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2347         return sig;
2348       }
2349     }
2350     sig_strm.next();
2351   }
2352   return NULL;
2353 }
2354 
2355 
2356 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2357                                                             Symbol* signature,
2358                                                             TRAPS) {
2359   methodHandle empty;
2360   assert(EnableInvokeDynamic, "");
2361   assert(MethodHandles::is_signature_polymorphic(iid) &&
2362          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2363          iid != vmIntrinsics::_invokeGeneric,
2364          err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));
2365 
2366   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2367   int          index = invoke_method_table()->hash_to_index(hash);
2368   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2369   methodHandle m;
2370   if (spe == NULL || spe->method() == NULL) {
2371     spe = NULL;
2372     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2373     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2374     if (!Arguments::is_interpreter_only()) {
2375       // Generate a compiled form of the MH intrinsic.
2376       AdapterHandlerLibrary::create_native_wrapper(m);
2377       // Check if have the compiled code.
2378       if (!m->has_compiled_code()) {
2379         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2380                    "out of space in CodeCache for method handle intrinsic", empty);
2381       }
2382     }
2383     // Now grab the lock.  We might have to throw away the new method,
2384     // if a racing thread has managed to install one at the same time.
2385     {
2386       MutexLocker ml(SystemDictionary_lock, THREAD);
2387       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2388       if (spe == NULL)
2389         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2390       if (spe->method() == NULL)
2391         spe->set_method(m());
2392     }
2393   }
2394 
2395   assert(spe != NULL && spe->method() != NULL, "");
2396   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2397          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2398          "MH intrinsic invariant");
2399   return spe->method();
2400 }
2401 
2402 // Helper for unpacking the return value from linkMethod and linkCallSite.
2403 static methodHandle unpack_method_and_appendix(Handle mname,
2404                                                KlassHandle accessing_klass,
2405                                                objArrayHandle appendix_box,
2406                                                Handle* appendix_result,
2407                                                TRAPS) {
2408   methodHandle empty;
2409   if (mname.not_null()) {
2410     Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2411     if (vmtarget != NULL && vmtarget->is_method()) {
2412       Method* m = (Method*)vmtarget;
2413       oop appendix = appendix_box->obj_at(0);
2414       if (TraceMethodHandles) {
2415     #ifndef PRODUCT
2416         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2417         m->print();
2418         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2419         tty->cr();
2420     #endif //PRODUCT
2421       }
2422       (*appendix_result) = Handle(THREAD, appendix);
2423       // the target is stored in the cpCache and if a reference to this
2424       // MethodName is dropped we need a way to make sure the
2425       // class_loader containing this method is kept alive.
2426       // FIXME: the appendix might also preserve this dependency.
2427       ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2428       this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2429       return methodHandle(THREAD, m);
2430     }
2431   }
2432   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2433   return empty;
2434 }
2435 
2436 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2437                                                           Symbol* signature,
2438                                                           KlassHandle accessing_klass,
2439                                                           Handle *appendix_result,
2440                                                           Handle *method_type_result,
2441                                                           TRAPS) {
2442   methodHandle empty;
2443   assert(EnableInvokeDynamic, "");
2444   assert(!THREAD->is_Compiler_thread(), "");
2445   Handle method_type =
2446     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2447 
2448   KlassHandle  mh_klass = SystemDictionary::MethodHandle_klass();
2449   int ref_kind = JVM_REF_invokeVirtual;
2450   Handle name_str = StringTable::intern(name, CHECK_(empty));
2451   objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2452   assert(appendix_box->obj_at(0) == NULL, "");
2453 
2454   // This should not happen.  JDK code should take care of that.
2455   if (accessing_klass.is_null() || method_type.is_null()) {
2456     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2457   }
2458 
2459   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2460   JavaCallArguments args;
2461   args.push_oop(accessing_klass()->java_mirror());
2462   args.push_int(ref_kind);
2463   args.push_oop(mh_klass()->java_mirror());
2464   args.push_oop(name_str());
2465   args.push_oop(method_type());
2466   args.push_oop(appendix_box());
2467   JavaValue result(T_OBJECT);
2468   JavaCalls::call_static(&result,
2469                          SystemDictionary::MethodHandleNatives_klass(),
2470                          vmSymbols::linkMethod_name(),
2471                          vmSymbols::linkMethod_signature(),
2472                          &args, CHECK_(empty));
2473   Handle mname(THREAD, (oop) result.get_jobject());
2474   (*method_type_result) = method_type;
2475   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2476 }
2477 
2478 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2479 // We must ensure that all class loaders everywhere will reach this class, for any client.
2480 // This is a safe bet for public classes in java.lang, such as Object and String.
2481 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2482 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2483 static bool is_always_visible_class(oop mirror) {
2484   Klass* klass = java_lang_Class::as_Klass(mirror);
2485   if (klass->oop_is_objArray()) {
2486     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2487   }
2488   if (klass->oop_is_typeArray()) {
2489     return true; // primitive array
2490   }
2491   assert(klass->oop_is_instance(), klass->external_name());
2492   return klass->is_public() &&
2493          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2494           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2495 }
2496 
2497 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2498 // signature, as interpreted relative to the given class loader.
2499 // Because of class loader constraints, all method handle usage must be
2500 // consistent with this loader.
2501 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2502                                                  KlassHandle accessing_klass,
2503                                                  TRAPS) {
2504   Handle empty;
2505   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2506   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2507   int          index = invoke_method_table()->hash_to_index(hash);
2508   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2509   if (spe != NULL && spe->method_type() != NULL) {
2510     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2511     return Handle(THREAD, spe->method_type());
2512   } else if (THREAD->is_Compiler_thread()) {
2513     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2514     return Handle();  // do not attempt from within compiler, unless it was cached
2515   }
2516 
2517   Handle class_loader, protection_domain;
2518   if (accessing_klass.not_null()) {
2519     class_loader      = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2520     protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2521   }
2522   bool can_be_cached = true;
2523   int npts = ArgumentCount(signature).size();
2524   objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2525   int arg = 0;
2526   Handle rt; // the return type from the signature
2527   ResourceMark rm(THREAD);
2528   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2529     oop mirror = NULL;
2530     if (can_be_cached) {
2531       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2532       mirror = ss.as_java_mirror(Handle(), Handle(),
2533                                  SignatureStream::ReturnNull, CHECK_(empty));
2534       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2535         // Fall back to accessing_klass context.
2536         can_be_cached = false;
2537       }
2538     }
2539     if (!can_be_cached) {
2540       // Resolve, throwing a real error if it doesn't work.
2541       mirror = ss.as_java_mirror(class_loader, protection_domain,
2542                                  SignatureStream::NCDFError, CHECK_(empty));
2543     }
2544     assert(!oopDesc::is_null(mirror), ss.as_symbol(THREAD)->as_C_string());
2545     if (ss.at_return_type())
2546       rt = Handle(THREAD, mirror);
2547     else
2548       pts->obj_at_put(arg++, mirror);
2549 
2550     // Check accessibility.
2551     if (ss.is_object() && accessing_klass.not_null()) {
2552       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2553       mirror = NULL;  // safety
2554       // Emulate ConstantPool::verify_constant_pool_resolve.
2555       if (sel_klass->oop_is_objArray())
2556         sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2557       if (sel_klass->oop_is_instance()) {
2558         KlassHandle sel_kh(THREAD, sel_klass);
2559         LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2560       }
2561     }
2562   }
2563   assert(arg == npts, "");
2564 
2565   // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2566   JavaCallArguments args(Handle(THREAD, rt()));
2567   args.push_oop(pts());
2568   JavaValue result(T_OBJECT);
2569   JavaCalls::call_static(&result,
2570                          SystemDictionary::MethodHandleNatives_klass(),
2571                          vmSymbols::findMethodHandleType_name(),
2572                          vmSymbols::findMethodHandleType_signature(),
2573                          &args, CHECK_(empty));
2574   Handle method_type(THREAD, (oop) result.get_jobject());
2575 
2576   if (can_be_cached) {
2577     // We can cache this MethodType inside the JVM.
2578     MutexLocker ml(SystemDictionary_lock, THREAD);
2579     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2580     if (spe == NULL)
2581       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2582     if (spe->method_type() == NULL) {
2583       spe->set_method_type(method_type());
2584     }
2585   }
2586 
2587   // report back to the caller with the MethodType
2588   return method_type;
2589 }
2590 
2591 // Ask Java code to find or construct a method handle constant.
2592 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2593                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2594                                                      KlassHandle callee,
2595                                                      Symbol* name_sym,
2596                                                      Symbol* signature,
2597                                                      TRAPS) {
2598   Handle empty;
2599   Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2600   Handle type;
2601   if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2602     type = find_method_handle_type(signature, caller, CHECK_(empty));
2603   } else if (caller.is_null()) {
2604     // This should not happen.  JDK code should take care of that.
2605     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2606   } else {
2607     ResourceMark rm(THREAD);
2608     SignatureStream ss(signature, false);
2609     if (!ss.is_done()) {
2610       oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2611                                      SignatureStream::NCDFError, CHECK_(empty));
2612       type = Handle(THREAD, mirror);
2613       ss.next();
2614       if (!ss.is_done())  type = Handle();  // error!
2615     }
2616   }
2617   if (type.is_null()) {
2618     THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2619   }
2620 
2621   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2622   JavaCallArguments args;
2623   args.push_oop(caller->java_mirror());  // the referring class
2624   args.push_int(ref_kind);
2625   args.push_oop(callee->java_mirror());  // the target class
2626   args.push_oop(name());
2627   args.push_oop(type());
2628   JavaValue result(T_OBJECT);
2629   JavaCalls::call_static(&result,
2630                          SystemDictionary::MethodHandleNatives_klass(),
2631                          vmSymbols::linkMethodHandleConstant_name(),
2632                          vmSymbols::linkMethodHandleConstant_signature(),
2633                          &args, CHECK_(empty));
2634   return Handle(THREAD, (oop) result.get_jobject());
2635 }
2636 
2637 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2638 // name and signature, as interpreted relative to the given class loader.
2639 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2640                                                               Handle bootstrap_specifier,
2641                                                               Symbol* name,
2642                                                               Symbol* type,
2643                                                               Handle *appendix_result,
2644                                                               Handle *method_type_result,
2645                                                               TRAPS) {
2646   methodHandle empty;
2647   Handle bsm, info;
2648   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2649     bsm = bootstrap_specifier;
2650   } else {
2651     assert(bootstrap_specifier->is_objArray(), "");
2652     objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2653     int len = args->length();
2654     assert(len >= 1, "");
2655     bsm = Handle(THREAD, args->obj_at(0));
2656     if (len > 1) {
2657       objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2658       for (int i = 1; i < len; i++)
2659         args1->obj_at_put(i-1, args->obj_at(i));
2660       info = Handle(THREAD, args1);
2661     }
2662   }
2663   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2664             "caller must supply a valid BSM");
2665 
2666   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2667   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2668 
2669   // This should not happen.  JDK code should take care of that.
2670   if (caller.is_null() || method_type.is_null()) {
2671     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2672   }
2673 
2674   objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2675   assert(appendix_box->obj_at(0) == NULL, "");
2676 
2677   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2678   JavaCallArguments args;
2679   args.push_oop(caller->java_mirror());
2680   args.push_oop(bsm());
2681   args.push_oop(method_name());
2682   args.push_oop(method_type());
2683   args.push_oop(info());
2684   args.push_oop(appendix_box);
2685   JavaValue result(T_OBJECT);
2686   JavaCalls::call_static(&result,
2687                          SystemDictionary::MethodHandleNatives_klass(),
2688                          vmSymbols::linkCallSite_name(),
2689                          vmSymbols::linkCallSite_signature(),
2690                          &args, CHECK_(empty));
2691   Handle mname(THREAD, (oop) result.get_jobject());
2692   (*method_type_result) = method_type;
2693   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2694 }
2695 
2696 // Since the identity hash code for symbols changes when the symbols are
2697 // moved from the regular perm gen (hash in the mark word) to the shared
2698 // spaces (hash is the address), the classes loaded into the dictionary
2699 // may be in the wrong buckets.
2700 
2701 void SystemDictionary::reorder_dictionary() {
2702   dictionary()->reorder_dictionary();
2703 }
2704 
2705 
2706 void SystemDictionary::copy_buckets(char** top, char* end) {
2707   dictionary()->copy_buckets(top, end);
2708 }
2709 
2710 
2711 void SystemDictionary::copy_table(char** top, char* end) {
2712   dictionary()->copy_table(top, end);
2713 }
2714 
2715 
2716 void SystemDictionary::reverse() {
2717   dictionary()->reverse();
2718 }
2719 
2720 int SystemDictionary::number_of_classes() {
2721   return dictionary()->number_of_entries();
2722 }
2723 
2724 
2725 // ----------------------------------------------------------------------------
2726 void SystemDictionary::print_shared(bool details) {
2727   shared_dictionary()->print(details);
2728 }
2729 
2730 void SystemDictionary::print(bool details) {
2731   dictionary()->print(details);
2732 
2733   // Placeholders
2734   GCMutexLocker mu(SystemDictionary_lock);
2735   placeholders()->print();
2736 
2737   // loader constraints - print under SD_lock
2738   constraints()->print();
2739 }
2740 
2741 
2742 void SystemDictionary::verify() {
2743   guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2744   guarantee(constraints() != NULL,
2745             "Verify of loader constraints failed");
2746   guarantee(dictionary()->number_of_entries() >= 0 &&
2747             placeholders()->number_of_entries() >= 0,
2748             "Verify of system dictionary failed");
2749 
2750   // Verify dictionary
2751   dictionary()->verify();
2752 
2753   GCMutexLocker mu(SystemDictionary_lock);
2754   placeholders()->verify();
2755 
2756   // Verify constraint table
2757   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2758   constraints()->verify(dictionary(), placeholders());
2759 }
2760 
2761 #ifndef PRODUCT
2762 
2763 // statistics code
2764 class ClassStatistics: AllStatic {
2765  private:
2766   static int nclasses;        // number of classes
2767   static int nmethods;        // number of methods
2768   static int nmethoddata;     // number of methodData
2769   static int class_size;      // size of class objects in words
2770   static int method_size;     // size of method objects in words
2771   static int debug_size;      // size of debug info in methods
2772   static int methoddata_size; // size of methodData objects in words
2773 
2774   static void do_class(Klass* k) {
2775     nclasses++;
2776     class_size += k->size();
2777     if (k->oop_is_instance()) {
2778       InstanceKlass* ik = (InstanceKlass*)k;
2779       class_size += ik->methods()->size();
2780       class_size += ik->constants()->size();
2781       class_size += ik->local_interfaces()->size();
2782       class_size += ik->transitive_interfaces()->size();
2783       // We do not have to count implementors, since we only store one!
2784       // SSS: How should these be accounted now that they have moved?
2785       // class_size += ik->fields()->length();
2786     }
2787   }
2788 
2789   static void do_method(Method* m) {
2790     nmethods++;
2791     method_size += m->size();
2792     // class loader uses same objArray for empty vectors, so don't count these
2793     if (m->has_stackmap_table()) {
2794       method_size += m->stackmap_data()->size();
2795     }
2796 
2797     MethodData* mdo = m->method_data();
2798     if (mdo != NULL) {
2799       nmethoddata++;
2800       methoddata_size += mdo->size();
2801     }
2802   }
2803 
2804  public:
2805   static void print() {
2806     SystemDictionary::classes_do(do_class);
2807     SystemDictionary::methods_do(do_method);
2808     tty->print_cr("Class statistics:");
2809     tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2810     tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2811                   (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2812     tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2813   }
2814 };
2815 
2816 
2817 int ClassStatistics::nclasses        = 0;
2818 int ClassStatistics::nmethods        = 0;
2819 int ClassStatistics::nmethoddata     = 0;
2820 int ClassStatistics::class_size      = 0;
2821 int ClassStatistics::method_size     = 0;
2822 int ClassStatistics::debug_size      = 0;
2823 int ClassStatistics::methoddata_size = 0;
2824 
2825 void SystemDictionary::print_class_statistics() {
2826   ResourceMark rm;
2827   ClassStatistics::print();
2828 }
2829 
2830 
2831 class MethodStatistics: AllStatic {
2832  public:
2833   enum {
2834     max_parameter_size = 10
2835   };
2836  private:
2837 
2838   static int _number_of_methods;
2839   static int _number_of_final_methods;
2840   static int _number_of_static_methods;
2841   static int _number_of_native_methods;
2842   static int _number_of_synchronized_methods;
2843   static int _number_of_profiled_methods;
2844   static int _number_of_bytecodes;
2845   static int _parameter_size_profile[max_parameter_size];
2846   static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2847 
2848   static void initialize() {
2849     _number_of_methods        = 0;
2850     _number_of_final_methods  = 0;
2851     _number_of_static_methods = 0;
2852     _number_of_native_methods = 0;
2853     _number_of_synchronized_methods = 0;
2854     _number_of_profiled_methods = 0;
2855     _number_of_bytecodes      = 0;
2856     for (int i = 0; i < max_parameter_size             ; i++) _parameter_size_profile[i] = 0;
2857     for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile     [j] = 0;
2858   };
2859 
2860   static void do_method(Method* m) {
2861     _number_of_methods++;
2862     // collect flag info
2863     if (m->is_final()       ) _number_of_final_methods++;
2864     if (m->is_static()      ) _number_of_static_methods++;
2865     if (m->is_native()      ) _number_of_native_methods++;
2866     if (m->is_synchronized()) _number_of_synchronized_methods++;
2867     if (m->method_data() != NULL) _number_of_profiled_methods++;
2868     // collect parameter size info (add one for receiver, if any)
2869     _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2870     // collect bytecodes info
2871     {
2872       Thread *thread = Thread::current();
2873       HandleMark hm(thread);
2874       BytecodeStream s(methodHandle(thread, m));
2875       Bytecodes::Code c;
2876       while ((c = s.next()) >= 0) {
2877         _number_of_bytecodes++;
2878         _bytecodes_profile[c]++;
2879       }
2880     }
2881   }
2882 
2883  public:
2884   static void print() {
2885     initialize();
2886     SystemDictionary::methods_do(do_method);
2887     // generate output
2888     tty->cr();
2889     tty->print_cr("Method statistics (static):");
2890     // flag distribution
2891     tty->cr();
2892     tty->print_cr("%6d final        methods  %6.1f%%", _number_of_final_methods       , _number_of_final_methods        * 100.0F / _number_of_methods);
2893     tty->print_cr("%6d static       methods  %6.1f%%", _number_of_static_methods      , _number_of_static_methods       * 100.0F / _number_of_methods);
2894     tty->print_cr("%6d native       methods  %6.1f%%", _number_of_native_methods      , _number_of_native_methods       * 100.0F / _number_of_methods);
2895     tty->print_cr("%6d synchronized methods  %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2896     tty->print_cr("%6d profiled     methods  %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2897     // parameter size profile
2898     tty->cr();
2899     { int tot = 0;
2900       int avg = 0;
2901       for (int i = 0; i < max_parameter_size; i++) {
2902         int n = _parameter_size_profile[i];
2903         tot += n;
2904         avg += n*i;
2905         tty->print_cr("parameter size = %1d: %6d methods  %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2906       }
2907       assert(tot == _number_of_methods, "should be the same");
2908       tty->print_cr("                    %6d methods  100.0%%", _number_of_methods);
2909       tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2910     }
2911     // bytecodes profile
2912     tty->cr();
2913     { int tot = 0;
2914       for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2915         if (Bytecodes::is_defined(i)) {
2916           Bytecodes::Code c = Bytecodes::cast(i);
2917           int n = _bytecodes_profile[c];
2918           tot += n;
2919           tty->print_cr("%9d  %7.3f%%  %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2920         }
2921       }
2922       assert(tot == _number_of_bytecodes, "should be the same");
2923       tty->print_cr("%9d  100.000%%", _number_of_bytecodes);
2924     }
2925     tty->cr();
2926   }
2927 };
2928 
2929 int MethodStatistics::_number_of_methods;
2930 int MethodStatistics::_number_of_final_methods;
2931 int MethodStatistics::_number_of_static_methods;
2932 int MethodStatistics::_number_of_native_methods;
2933 int MethodStatistics::_number_of_synchronized_methods;
2934 int MethodStatistics::_number_of_profiled_methods;
2935 int MethodStatistics::_number_of_bytecodes;
2936 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2937 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2938 
2939 
2940 void SystemDictionary::print_method_statistics() {
2941   MethodStatistics::print();
2942 }
2943 
2944 #endif // PRODUCT