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, class_loader, protection_domain, throw_error, k_h, THREAD);
 189   }
 190   return klass;
 191 }
 192 
 193 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
 194   if (HAS_PENDING_EXCEPTION) {
 195     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 196     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 197     // and if so convert it to a NoClassDefFoundError
 198     // And chain the original ClassNotFoundException
 199     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 200       ResourceMark rm(THREAD);
 201       assert(klass_h() == NULL, "Should not have result with exception pending");
 202       Handle e(THREAD, PENDING_EXCEPTION);
 203       CLEAR_PENDING_EXCEPTION;
 204       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 205     } else {
 206       return NULL;
 207     }
 208   }
 209   // Class not found, throw appropriate error or exception depending on value of throw_error
 210   if (klass_h() == NULL) {
 211     ResourceMark rm(THREAD);
 212     if (throw_error) {
 213       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 214     } else {
 215       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 216     }
 217   }
 218   return (Klass*)klass_h();
 219 }
 220 
 221 
 222 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 223                                            bool throw_error, TRAPS)
 224 {
 225   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 226 }
 227 
 228 
 229 // Forwards to resolve_instance_class_or_null
 230 
 231 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 232   assert(!THREAD->is_Compiler_thread(),
 233          err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
 234                  class_name->as_C_string(),
 235                  class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
 236   if (FieldType::is_array(class_name)) {
 237     return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
 238   } else if (FieldType::is_obj(class_name)) {
 239     ResourceMark rm(THREAD);
 240     // Ignore wrapping L and ;.
 241     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 242                                    class_name->utf8_length() - 2, CHECK_NULL);
 243     return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
 244   } else {
 245     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
 246   }
 247 }
 248 
 249 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 250   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 251 }
 252 
 253 // Forwards to resolve_instance_class_or_null
 254 
 255 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 256                                                        Handle class_loader,
 257                                                        Handle protection_domain,
 258                                                        TRAPS) {
 259   assert(FieldType::is_array(class_name), "must be array");
 260   Klass* k = NULL;
 261   FieldArrayInfo fd;
 262   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 263   // of this call
 264   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 265   if (t == T_OBJECT) {
 266     // naked oop "k" is OK here -- we assign back into it
 267     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 268                                                          class_loader,
 269                                                          protection_domain,
 270                                                          CHECK_NULL);
 271     if (k != NULL) {
 272       k = k->array_klass(fd.dimension(), CHECK_NULL);
 273     }
 274   } else {
 275     k = Universe::typeArrayKlassObj(t);
 276     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 277   }
 278   return k;
 279 }
 280 
 281 
 282 // Must be called for any super-class or super-interface resolution
 283 // during class definition to allow class circularity checking
 284 // super-interface callers:
 285 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 286 // super-class callers:
 287 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 288 //   load_shared_class - while loading a class from shared archive
 289 //   resolve_instance_class_or_null:
 290 //     via: handle_parallel_super_load
 291 //      when resolving a class that has an existing placeholder with
 292 //      a saved superclass [i.e. a defineClass is currently in progress]
 293 //      if another thread is trying to resolve the class, it must do
 294 //      super-class checks on its own thread to catch class circularity
 295 // This last call is critical in class circularity checking for cases
 296 // where classloading is delegated to different threads and the
 297 // classloader lock is released.
 298 // Take the case: Base->Super->Base
 299 //   1. If thread T1 tries to do a defineClass of class Base
 300 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 301 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 302 //    so it tries to load Super
 303 //   3. If we load the class internally, or user classloader uses same thread
 304 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 305 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 306 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 307 //      3.4 calls resolve_super_or_fail Base
 308 //      3.5 finds T1,Base -> throws class circularity
 309 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 310 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 311 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 312 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 313 //      4.4 finds T2, Super -> throws class circularity
 314 // Must be called, even if superclass is null, since this is
 315 // where the placeholder entry is created which claims this
 316 // thread is loading this class/classloader.
 317 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 318                                                  Symbol* class_name,
 319                                                  Handle class_loader,
 320                                                  Handle protection_domain,
 321                                                  bool is_superclass,
 322                                                  TRAPS) {
 323   // Double-check, if child class is already loaded, just return super-class,interface
 324   // Don't add a placedholder if already loaded, i.e. already in system dictionary
 325   // Make sure there's a placeholder for the *child* before resolving.
 326   // Used as a claim that this thread is currently loading superclass/classloader
 327   // Used here for ClassCircularity checks and also for heap verification
 328   // (every InstanceKlass in the heap needs to be in the system dictionary
 329   // or have a placeholder).
 330   // Must check ClassCircularity before checking if super class is already loaded
 331   //
 332   // We might not already have a placeholder if this child_name was
 333   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 334   // the name of the class might not be known until the stream is actually
 335   // parsed.
 336   // Bugs 4643874, 4715493
 337   // compute_hash can have a safepoint
 338 
 339   ClassLoaderData* loader_data = class_loader_data(class_loader);
 340   unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
 341   int d_index = dictionary()->hash_to_index(d_hash);
 342   unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
 343   int p_index = placeholders()->hash_to_index(p_hash);
 344   // can't throw error holding a lock
 345   bool child_already_loaded = false;
 346   bool throw_circularity_error = false;
 347   {
 348     MutexLocker mu(SystemDictionary_lock, THREAD);
 349     Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
 350     Klass* quicksuperk;
 351     // to support // loading: if child done loading, just return superclass
 352     // if class_name, & class_loader don't match:
 353     // if initial define, SD update will give LinkageError
 354     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 355     // so we don't throw an exception here.
 356     // see: nsk redefclass014 & java.lang.instrument Instrument032
 357     if ((childk != NULL ) && (is_superclass) &&
 358        ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&
 359 
 360          ((quicksuperk->name() == class_name) &&
 361             (quicksuperk->class_loader()  == class_loader()))) {
 362            return quicksuperk;
 363     } else {
 364       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 365       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 366           throw_circularity_error = true;
 367       }
 368     }
 369     if (!throw_circularity_error) {
 370       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 371     }
 372   }
 373   if (throw_circularity_error) {
 374       ResourceMark rm(THREAD);
 375       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 376   }
 377 
 378 // java.lang.Object should have been found above
 379   assert(class_name != NULL, "null super class for resolving");
 380   // Resolve the super class or interface, check results on return
 381   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 382                                                  class_loader,
 383                                                  protection_domain,
 384                                                  THREAD);
 385 
 386   KlassHandle superk_h(THREAD, superk);
 387 
 388   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 389   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 390   // or error. GC used to walk the placeholder table as strong roots.
 391   // The instanceKlass is kept alive because the class loader is on the stack,
 392   // which keeps the loader_data alive, as well as all instanceKlasses in
 393   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 394   {
 395     MutexLocker mu(SystemDictionary_lock, THREAD);
 396     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 397     SystemDictionary_lock->notify_all();
 398   }
 399   if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
 400     // can null superk
 401     superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
 402   }
 403 
 404   return superk_h();
 405 }
 406 
 407 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
 408                                                   Handle class_loader,
 409                                                   Handle protection_domain,
 410                                                   TRAPS) {
 411   if(!has_checkPackageAccess()) return;
 412 
 413   // Now we have to call back to java to check if the initating class has access
 414   JavaValue result(T_VOID);
 415   if (TraceProtectionDomainVerification) {
 416     // Print out trace information
 417     tty->print_cr("Checking package access");
 418     tty->print(" - class loader:      "); class_loader()->print_value_on(tty);      tty->cr();
 419     tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
 420     tty->print(" - loading:           "); klass()->print_value_on(tty);             tty->cr();
 421   }
 422 
 423   KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
 424   JavaCalls::call_special(&result,
 425                          class_loader,
 426                          system_loader,
 427                          vmSymbols::checkPackageAccess_name(),
 428                          vmSymbols::class_protectiondomain_signature(),
 429                          Handle(THREAD, klass->java_mirror()),
 430                          protection_domain,
 431                          THREAD);
 432 
 433   if (TraceProtectionDomainVerification) {
 434     if (HAS_PENDING_EXCEPTION) {
 435       tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
 436     } else {
 437      tty->print_cr(" -> granted");
 438     }
 439     tty->cr();
 440   }
 441 
 442   if (HAS_PENDING_EXCEPTION) return;
 443 
 444   // If no exception has been thrown, we have validated the protection domain
 445   // Insert the protection domain of the initiating class into the set.
 446   {
 447     // We recalculate the entry here -- we've called out to java since
 448     // the last time it was calculated.
 449     ClassLoaderData* loader_data = class_loader_data(class_loader);
 450 
 451     Symbol*  kn = klass->name();
 452     unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
 453     int d_index = dictionary()->hash_to_index(d_hash);
 454 
 455     MutexLocker mu(SystemDictionary_lock, THREAD);
 456     {
 457       // Note that we have an entry, and entries can be deleted only during GC,
 458       // so we cannot allow GC to occur while we're holding this entry.
 459 
 460       // We're using a No_Safepoint_Verifier to catch any place where we
 461       // might potentially do a GC at all.
 462       // Dictionary::do_unloading() asserts that classes in SD are only
 463       // unloaded at a safepoint. Anonymous classes are not in SD.
 464       No_Safepoint_Verifier nosafepoint;
 465       dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
 466                                           protection_domain, THREAD);
 467     }
 468   }
 469 }
 470 
 471 // We only get here if this thread finds that another thread
 472 // has already claimed the placeholder token for the current operation,
 473 // but that other thread either never owned or gave up the
 474 // object lock
 475 // Waits on SystemDictionary_lock to indicate placeholder table updated
 476 // On return, caller must recheck placeholder table state
 477 //
 478 // We only get here if
 479 //  1) custom classLoader, i.e. not bootstrap classloader
 480 //  2) UnsyncloadClass not set
 481 //  3) custom classLoader has broken the class loader objectLock
 482 //     so another thread got here in parallel
 483 //
 484 // lockObject must be held.
 485 // Complicated dance due to lock ordering:
 486 // Must first release the classloader object lock to
 487 // allow initial definer to complete the class definition
 488 // and to avoid deadlock
 489 // Reclaim classloader lock object with same original recursion count
 490 // Must release SystemDictionary_lock after notify, since
 491 // class loader lock must be claimed before SystemDictionary_lock
 492 // to prevent deadlocks
 493 //
 494 // The notify allows applications that did an untimed wait() on
 495 // the classloader object lock to not hang.
 496 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 497   assert_lock_strong(SystemDictionary_lock);
 498 
 499   bool calledholdinglock
 500       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 501   assert(calledholdinglock,"must hold lock for notify");
 502   assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 503   ObjectSynchronizer::notifyall(lockObject, THREAD);
 504   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 505   SystemDictionary_lock->wait();
 506   SystemDictionary_lock->unlock();
 507   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 508   SystemDictionary_lock->lock();
 509 }
 510 
 511 // If the class in is in the placeholder table, class loading is in progress
 512 // For cases where the application changes threads to load classes, it
 513 // is critical to ClassCircularity detection that we try loading
 514 // the superclass on the same thread internally, so we do parallel
 515 // super class loading here.
 516 // This also is critical in cases where the original thread gets stalled
 517 // even in non-circularity situations.
 518 // Note: must call resolve_super_or_fail even if null super -
 519 // to force placeholder entry creation for this class for circularity detection
 520 // Caller must check for pending exception
 521 // Returns non-null Klass* if other thread has completed load
 522 // and we are done,
 523 // If return null Klass* and no pending exception, the caller must load the class
 524 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
 525     Symbol* name, Symbol* superclassname, Handle class_loader,
 526     Handle protection_domain, Handle lockObject, TRAPS) {
 527 
 528   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
 529   ClassLoaderData* loader_data = class_loader_data(class_loader);
 530   unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
 531   int d_index = dictionary()->hash_to_index(d_hash);
 532   unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
 533   int p_index = placeholders()->hash_to_index(p_hash);
 534 
 535   // superk is not used, resolve_super called for circularity check only
 536   // This code is reached in two situations. One if this thread
 537   // is loading the same class twice (e.g. ClassCircularity, or
 538   // java.lang.instrument).
 539   // The second is if another thread started the resolve_super first
 540   // and has not yet finished.
 541   // In both cases the original caller will clean up the placeholder
 542   // entry on error.
 543   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 544                                                           superclassname,
 545                                                           class_loader,
 546                                                           protection_domain,
 547                                                           true,
 548                                                           CHECK_(nh));
 549 
 550   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 551   // Serial class loaders and bootstrap classloader do wait for superclass loads
 552  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 553     MutexLocker mu(SystemDictionary_lock, THREAD);
 554     // Check if classloading completed while we were loading superclass or waiting
 555     Klass* check = find_class(d_index, d_hash, name, loader_data);
 556     if (check != NULL) {
 557       // Klass is already loaded, so just return it
 558       return(instanceKlassHandle(THREAD, check));
 559     } else {
 560       return nh;
 561     }
 562   }
 563 
 564   // must loop to both handle other placeholder updates
 565   // and spurious notifications
 566   bool super_load_in_progress = true;
 567   PlaceholderEntry* placeholder;
 568   while (super_load_in_progress) {
 569     MutexLocker mu(SystemDictionary_lock, THREAD);
 570     // Check if classloading completed while we were loading superclass or waiting
 571     Klass* check = find_class(d_index, d_hash, name, loader_data);
 572     if (check != NULL) {
 573       // Klass is already loaded, so just return it
 574       return(instanceKlassHandle(THREAD, check));
 575     } else {
 576       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 577       if (placeholder && placeholder->super_load_in_progress() ){
 578         // Before UnsyncloadClass:
 579         // We only get here if the application has released the
 580         // classloader lock when another thread was in the middle of loading a
 581         // superclass/superinterface for this class, and now
 582         // this thread is also trying to load this class.
 583         // To minimize surprises, the first thread that started to
 584         // load a class should be the one to complete the loading
 585         // with the classfile it initially expected.
 586         // This logic has the current thread wait once it has done
 587         // all the superclass/superinterface loading it can, until
 588         // the original thread completes the class loading or fails
 589         // If it completes we will use the resulting InstanceKlass
 590         // which we will find below in the systemDictionary.
 591         // We also get here for parallel bootstrap classloader
 592         if (class_loader.is_null()) {
 593           SystemDictionary_lock->wait();
 594         } else {
 595           double_lock_wait(lockObject, THREAD);
 596         }
 597       } else {
 598         // If not in SD and not in PH, other thread's load must have failed
 599         super_load_in_progress = false;
 600       }
 601     }
 602   }
 603   return (nh);
 604 }
 605 
 606 // utility function for class load event
 607 static void post_class_load_event(EventClassLoad &event,
 608                                   instanceKlassHandle k,
 609                                   Handle initiating_loader) {
 610 #if INCLUDE_JFR
 611   if (event.should_commit()) {
 612     event.set_loadedClass(k());
 613     event.set_definingClassLoader(k->class_loader_data());
 614     oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
 615     event.set_initiatingClassLoader(class_loader != NULL ?
 616                                     ClassLoaderData::class_loader_data_or_null(class_loader) :
 617                                     (ClassLoaderData*)NULL);
 618     event.commit();
 619   }
 620 #endif
 621 }
 622 
 623 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 624                                                         Handle class_loader,
 625                                                         Handle protection_domain,
 626                                                         TRAPS) {
 627   assert(name != NULL && !FieldType::is_array(name) &&
 628          !FieldType::is_obj(name), "invalid class name");
 629 
 630   EventClassLoad class_load_start_event;
 631 
 632   // UseNewReflection
 633   // Fix for 4474172; see evaluation for more details
 634   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 635   ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
 636 
 637   // Do lookup to see if class already exist and the protection domain
 638   // has the right access
 639   // This call uses find which checks protection domain already matches
 640   // All subsequent calls use find_class, and set has_loaded_class so that
 641   // before we return a result we call out to java to check for valid protection domain
 642   // to allow returning the Klass* and add it to the pd_set if it is valid
 643   unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
 644   int d_index = dictionary()->hash_to_index(d_hash);
 645   Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
 646                                       protection_domain, THREAD);
 647   if (probe != NULL) return probe;
 648 
 649 
 650   // Non-bootstrap class loaders will call out to class loader and
 651   // define via jvm/jni_DefineClass which will acquire the
 652   // class loader object lock to protect against multiple threads
 653   // defining the class in parallel by accident.
 654   // This lock must be acquired here so the waiter will find
 655   // any successful result in the SystemDictionary and not attempt
 656   // the define
 657   // ParallelCapable Classloaders and the bootstrap classloader,
 658   // or all classloaders with UnsyncloadClass do not acquire lock here
 659   bool DoObjectLock = true;
 660   if (is_parallelCapable(class_loader)) {
 661     DoObjectLock = false;
 662   }
 663 
 664   unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
 665   int p_index = placeholders()->hash_to_index(p_hash);
 666 
 667   // Class is not in SystemDictionary so we have to do loading.
 668   // Make sure we are synchronized on the class loader before we proceed
 669   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 670   check_loader_lock_contention(lockObject, THREAD);
 671   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 672 
 673   // Check again (after locking) if class already exist in SystemDictionary
 674   bool class_has_been_loaded   = false;
 675   bool super_load_in_progress  = false;
 676   bool havesupername = false;
 677   instanceKlassHandle k;
 678   PlaceholderEntry* placeholder;
 679   Symbol* superclassname = NULL;
 680 
 681   {
 682     MutexLocker mu(SystemDictionary_lock, THREAD);
 683     Klass* check = find_class(d_index, d_hash, name, loader_data);
 684     if (check != NULL) {
 685       // Klass is already loaded, so just return it
 686       class_has_been_loaded = true;
 687       k = instanceKlassHandle(THREAD, check);
 688     } else {
 689       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 690       if (placeholder && placeholder->super_load_in_progress()) {
 691          super_load_in_progress = true;
 692          if (placeholder->havesupername() == true) {
 693            superclassname = placeholder->supername();
 694            havesupername = true;
 695          }
 696       }
 697     }
 698   }
 699 
 700   // If the class is in the placeholder table, class loading is in progress
 701   if (super_load_in_progress && havesupername==true) {
 702     k = SystemDictionary::handle_parallel_super_load(name, superclassname,
 703         class_loader, protection_domain, lockObject, THREAD);
 704     if (HAS_PENDING_EXCEPTION) {
 705       return NULL;
 706     }
 707     if (!k.is_null()) {
 708       class_has_been_loaded = true;
 709     }
 710   }
 711 
 712   bool throw_circularity_error = false;
 713   if (!class_has_been_loaded) {
 714     bool load_instance_added = false;
 715 
 716     // add placeholder entry to record loading instance class
 717     // Five cases:
 718     // All cases need to prevent modifying bootclasssearchpath
 719     // in parallel with a classload of same classname
 720     // Redefineclasses uses existence of the placeholder for the duration
 721     // of the class load to prevent concurrent redefinition of not completely
 722     // defined classes.
 723     // case 1. traditional classloaders that rely on the classloader object lock
 724     //   - no other need for LOAD_INSTANCE
 725     // case 2. traditional classloaders that break the classloader object lock
 726     //    as a deadlock workaround. Detection of this case requires that
 727     //    this check is done while holding the classloader object lock,
 728     //    and that lock is still held when calling classloader's loadClass.
 729     //    For these classloaders, we ensure that the first requestor
 730     //    completes the load and other requestors wait for completion.
 731     // case 3. UnsyncloadClass - don't use objectLocker
 732     //    With this flag, we allow parallel classloading of a
 733     //    class/classloader pair
 734     // case4. Bootstrap classloader - don't own objectLocker
 735     //    This classloader supports parallelism at the classloader level,
 736     //    but only allows a single load of a class/classloader pair.
 737     //    No performance benefit and no deadlock issues.
 738     // case 5. parallelCapable user level classloaders - without objectLocker
 739     //    Allow parallel classloading of a class/classloader pair
 740 
 741     {
 742       MutexLocker mu(SystemDictionary_lock, THREAD);
 743       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 744         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 745         if (oldprobe) {
 746           // only need check_seen_thread once, not on each loop
 747           // 6341374 java/lang/Instrument with -Xcomp
 748           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 749             throw_circularity_error = true;
 750           } else {
 751             // case 1: traditional: should never see load_in_progress.
 752             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 753 
 754               // case 4: bootstrap classloader: prevent futile classloading,
 755               // wait on first requestor
 756               if (class_loader.is_null()) {
 757                 SystemDictionary_lock->wait();
 758               } else {
 759               // case 2: traditional with broken classloader lock. wait on first
 760               // requestor.
 761                 double_lock_wait(lockObject, THREAD);
 762               }
 763               // Check if classloading completed while we were waiting
 764               Klass* check = find_class(d_index, d_hash, name, loader_data);
 765               if (check != NULL) {
 766                 // Klass is already loaded, so just return it
 767                 k = instanceKlassHandle(THREAD, check);
 768                 class_has_been_loaded = true;
 769               }
 770               // check if other thread failed to load and cleaned up
 771               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 772             }
 773           }
 774         }
 775       }
 776       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 777       // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
 778       // LOAD_INSTANCE in parallel
 779 
 780       if (!throw_circularity_error && !class_has_been_loaded) {
 781         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 782         load_instance_added = true;
 783         // For class loaders that do not acquire the classloader object lock,
 784         // if they did not catch another thread holding LOAD_INSTANCE,
 785         // need a check analogous to the acquire ObjectLocker/find_class
 786         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 787         // one final check if the load has already completed
 788         // class loaders holding the ObjectLock shouldn't find the class here
 789         Klass* check = find_class(d_index, d_hash, name, loader_data);
 790         if (check != NULL) {
 791         // Klass is already loaded, so return it after checking/adding protection domain
 792           k = instanceKlassHandle(THREAD, check);
 793           class_has_been_loaded = true;
 794         }
 795       }
 796     }
 797 
 798     // must throw error outside of owning lock
 799     if (throw_circularity_error) {
 800       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 801       ResourceMark rm(THREAD);
 802       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 803     }
 804 
 805     if (!class_has_been_loaded) {
 806 
 807       // Do actual loading
 808       k = load_instance_class(name, class_loader, THREAD);
 809 
 810       // For UnsyncloadClass only
 811       // If they got a linkageError, check if a parallel class load succeeded.
 812       // If it did, then for bytecode resolution the specification requires
 813       // that we return the same result we did for the other thread, i.e. the
 814       // successfully loaded InstanceKlass
 815       // Should not get here for classloaders that support parallelism
 816       // with the new cleaner mechanism, even with AllowParallelDefineClass
 817       // Bootstrap goes through here to allow for an extra guarantee check
 818       if (UnsyncloadClass || (class_loader.is_null())) {
 819         if (k.is_null() && HAS_PENDING_EXCEPTION
 820           && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
 821           MutexLocker mu(SystemDictionary_lock, THREAD);
 822           Klass* check = find_class(d_index, d_hash, name, loader_data);
 823           if (check != NULL) {
 824             // Klass is already loaded, so just use it
 825             k = instanceKlassHandle(THREAD, check);
 826             CLEAR_PENDING_EXCEPTION;
 827             guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
 828           }
 829         }
 830       }
 831 
 832       // If everything was OK (no exceptions, no null return value), and
 833       // class_loader is NOT the defining loader, do a little more bookkeeping.
 834       if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
 835         k->class_loader() != class_loader()) {
 836 
 837         check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
 838 
 839         // Need to check for a PENDING_EXCEPTION again; check_constraints
 840         // can throw but we may have to remove entry from the placeholder table below.
 841         if (!HAS_PENDING_EXCEPTION) {
 842           // Record dependency for non-parent delegation.
 843           // This recording keeps the defining class loader of the klass (k) found
 844           // from being unloaded while the initiating class loader is loaded
 845           // even if the reference to the defining class loader is dropped
 846           // before references to the initiating class loader.
 847           loader_data->record_dependency(k(), THREAD);
 848         }
 849 
 850         if (!HAS_PENDING_EXCEPTION) {
 851           { // Grabbing the Compile_lock prevents systemDictionary updates
 852             // during compilations.
 853             MutexLocker mu(Compile_lock, THREAD);
 854             update_dictionary(d_index, d_hash, p_index, p_hash,
 855                               k, class_loader, THREAD);
 856           }
 857 
 858           if (JvmtiExport::should_post_class_load()) {
 859             Thread *thread = THREAD;
 860             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 861             JvmtiExport::post_class_load((JavaThread *) thread, k());
 862           }
 863         }
 864       }
 865     } // load_instance_class loop
 866 
 867     if (load_instance_added == true) {
 868       // clean up placeholder entries for LOAD_INSTANCE success or error
 869       // This brackets the SystemDictionary updates for both defining
 870       // and initiating loaders
 871       MutexLocker mu(SystemDictionary_lock, THREAD);
 872       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 873       SystemDictionary_lock->notify_all();
 874     }
 875   }
 876 
 877   if (HAS_PENDING_EXCEPTION || k.is_null()) {
 878     return NULL;
 879   }
 880 
 881   post_class_load_event(class_load_start_event, k, class_loader);
 882 
 883 #ifdef ASSERT
 884   {
 885     ClassLoaderData* loader_data = k->class_loader_data();
 886     MutexLocker mu(SystemDictionary_lock, THREAD);
 887     Klass* kk = find_class(name, loader_data);
 888     assert(kk == k(), "should be present in dictionary");
 889   }
 890 #endif
 891 
 892   // return if the protection domain in NULL
 893   if (protection_domain() == NULL) return k();
 894 
 895   // Check the protection domain has the right access
 896   {
 897     MutexLocker mu(SystemDictionary_lock, THREAD);
 898     // Note that we have an entry, and entries can be deleted only during GC,
 899     // so we cannot allow GC to occur while we're holding this entry.
 900     // We're using a No_Safepoint_Verifier to catch any place where we
 901     // might potentially do a GC at all.
 902     // Dictionary::do_unloading() asserts that classes in SD are only
 903     // unloaded at a safepoint. Anonymous classes are not in SD.
 904     No_Safepoint_Verifier nosafepoint;
 905     if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
 906                                                  loader_data,
 907                                                  protection_domain)) {
 908       return k();
 909     }
 910   }
 911 
 912   // Verify protection domain. If it fails an exception is thrown
 913   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 914 
 915   return k();
 916 }
 917 
 918 
 919 // This routine does not lock the system dictionary.
 920 //
 921 // Since readers don't hold a lock, we must make sure that system
 922 // dictionary entries are only removed at a safepoint (when only one
 923 // thread is running), and are added to in a safe way (all links must
 924 // be updated in an MT-safe manner).
 925 //
 926 // Callers should be aware that an entry could be added just after
 927 // _dictionary->bucket(index) is read here, so the caller will not see
 928 // the new entry.
 929 
 930 Klass* SystemDictionary::find(Symbol* class_name,
 931                               Handle class_loader,
 932                               Handle protection_domain,
 933                               TRAPS) {
 934 
 935   // UseNewReflection
 936   // The result of this call should be consistent with the result
 937   // of the call to resolve_instance_class_or_null().
 938   // See evaluation 6790209 and 4474172 for more details.
 939   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 940   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 941 
 942   if (loader_data == NULL) {
 943     // If the ClassLoaderData has not been setup,
 944     // then the class loader has no entries in the dictionary.
 945     return NULL;
 946   }
 947 
 948   unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
 949   int d_index = dictionary()->hash_to_index(d_hash);
 950 
 951   {
 952     // Note that we have an entry, and entries can be deleted only during GC,
 953     // so we cannot allow GC to occur while we're holding this entry.
 954     // We're using a No_Safepoint_Verifier to catch any place where we
 955     // might potentially do a GC at all.
 956     // Dictionary::do_unloading() asserts that classes in SD are only
 957     // unloaded at a safepoint. Anonymous classes are not in SD.
 958     No_Safepoint_Verifier nosafepoint;
 959     return dictionary()->find(d_index, d_hash, class_name, loader_data,
 960                               protection_domain, THREAD);
 961   }
 962 }
 963 
 964 
 965 // Look for a loaded instance or array klass by name.  Do not do any loading.
 966 // return NULL in case of error.
 967 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 968                                                       Handle class_loader,
 969                                                       Handle protection_domain,
 970                                                       TRAPS) {
 971   Klass* k = NULL;
 972   assert(class_name != NULL, "class name must be non NULL");
 973 
 974   if (FieldType::is_array(class_name)) {
 975     // The name refers to an array.  Parse the name.
 976     // dimension and object_key in FieldArrayInfo are assigned as a
 977     // side-effect of this call
 978     FieldArrayInfo fd;
 979     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 980     if (t != T_OBJECT) {
 981       k = Universe::typeArrayKlassObj(t);
 982     } else {
 983       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 984     }
 985     if (k != NULL) {
 986       k = k->array_klass_or_null(fd.dimension());
 987     }
 988   } else {
 989     k = find(class_name, class_loader, protection_domain, THREAD);
 990   }
 991   return k;
 992 }
 993 
 994 // Note: this method is much like resolve_from_stream, but
 995 // updates no supplemental data structures.
 996 // TODO consolidate the two methods with a helper routine?
 997 Klass* SystemDictionary::parse_stream(Symbol* class_name,
 998                                       Handle class_loader,
 999                                       Handle protection_domain,
1000                                       ClassFileStream* st,
1001                                       KlassHandle host_klass,
1002                                       GrowableArray<Handle>* cp_patches,
1003                                       TRAPS) {
1004   TempNewSymbol parsed_name = NULL;
1005 
1006   EventClassLoad class_load_start_event;
1007 
1008   ClassLoaderData* loader_data;
1009   if (host_klass.not_null()) {
1010     // Create a new CLD for anonymous class, that uses the same class loader
1011     // as the host_klass
1012     assert(EnableInvokeDynamic, "");
1013     guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1014     guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
1015     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1016     loader_data->record_dependency(host_klass(), CHECK_NULL);
1017   } else {
1018     loader_data = ClassLoaderData::class_loader_data(class_loader());
1019   }
1020 
1021   // Parse the stream. Note that we do this even though this klass might
1022   // already be present in the SystemDictionary, otherwise we would not
1023   // throw potential ClassFormatErrors.
1024   //
1025   // Note: "name" is updated.
1026 
1027   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1028                                                              loader_data,
1029                                                              protection_domain,
1030                                                              host_klass,
1031                                                              cp_patches,
1032                                                              parsed_name,
1033                                                              true,
1034                                                              THREAD);
1035 
1036 
1037   if (host_klass.not_null() && k.not_null()) {
1038     assert(EnableInvokeDynamic, "");
1039     // If it's anonymous, initialize it now, since nobody else will.
1040 
1041     {
1042       MutexLocker mu_r(Compile_lock, THREAD);
1043 
1044       // Add to class hierarchy, initialize vtables, and do possible
1045       // deoptimizations.
1046       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1047 
1048       // But, do not add to system dictionary.
1049 
1050       // compiled code dependencies need to be validated anyway
1051       notice_modification();
1052     }
1053 
1054     // Rewrite and patch constant pool here.
1055     k->link_class(CHECK_NULL);
1056     if (cp_patches != NULL) {
1057       k->constants()->patch_resolved_references(cp_patches);
1058     }
1059     k->eager_initialize(CHECK_NULL);
1060 
1061     // notify jvmti
1062     if (JvmtiExport::should_post_class_load()) {
1063         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1064         JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1065     }
1066 
1067     post_class_load_event(class_load_start_event, k, class_loader);
1068   }
1069   assert(host_klass.not_null() || cp_patches == NULL,
1070          "cp_patches only found with host_klass");
1071 
1072   return k();
1073 }
1074 
1075 // Add a klass to the system from a stream (called by jni_DefineClass and
1076 // JVM_DefineClass).
1077 // Note: class_name can be NULL. In that case we do not know the name of
1078 // the class until we have parsed the stream.
1079 
1080 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1081                                              Handle class_loader,
1082                                              Handle protection_domain,
1083                                              ClassFileStream* st,
1084                                              bool verify,
1085                                              TRAPS) {
1086 
1087   // Classloaders that support parallelism, e.g. bootstrap classloader,
1088   // or all classloaders with UnsyncloadClass do not acquire lock here
1089   bool DoObjectLock = true;
1090   if (is_parallelCapable(class_loader)) {
1091     DoObjectLock = false;
1092   }
1093 
1094   ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1095 
1096   // Make sure we are synchronized on the class loader before we proceed
1097   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1098   check_loader_lock_contention(lockObject, THREAD);
1099   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1100 
1101   TempNewSymbol parsed_name = NULL;
1102 
1103   // Parse the stream. Note that we do this even though this klass might
1104   // already be present in the SystemDictionary, otherwise we would not
1105   // throw potential ClassFormatErrors.
1106   //
1107   // Note: "name" is updated.
1108 
1109   ClassFileParser parser(st);
1110   instanceKlassHandle k = parser.parseClassFile(class_name,
1111                                                 loader_data,
1112                                                 protection_domain,
1113                                                 parsed_name,
1114                                                 verify,
1115                                                 THREAD);
1116 
1117   const char* pkg = "java/";
1118   size_t pkglen = strlen(pkg);
1119   if (!HAS_PENDING_EXCEPTION &&
1120       !class_loader.is_null() &&
1121       parsed_name != NULL &&
1122       parsed_name->utf8_length() >= (int)pkglen &&
1123       !strncmp((const char*)parsed_name->bytes(), pkg, pkglen)) {
1124     // It is illegal to define classes in the "java." package from
1125     // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1126     ResourceMark rm(THREAD);
1127     char* name = parsed_name->as_C_string();
1128     char* index = strrchr(name, '/');
1129     assert(index != NULL, "must be");
1130     *index = '\0'; // chop to just the package name
1131     while ((index = strchr(name, '/')) != NULL) {
1132       *index = '.'; // replace '/' with '.' in package name
1133     }
1134     const char* fmt = "Prohibited package name: %s";
1135     size_t len = strlen(fmt) + strlen(name);
1136     char* message = NEW_RESOURCE_ARRAY(char, len);
1137     jio_snprintf(message, len, fmt, name);
1138     Exceptions::_throw_msg(THREAD_AND_LOCATION,
1139       vmSymbols::java_lang_SecurityException(), message);
1140   }
1141 
1142   if (!HAS_PENDING_EXCEPTION) {
1143     assert(parsed_name != NULL, "Sanity");
1144     assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1145     // Verification prevents us from creating names with dots in them, this
1146     // asserts that that's the case.
1147     assert(is_internal_format(parsed_name),
1148            "external class name format used internally");
1149 
1150 #if INCLUDE_JFR
1151     {
1152       InstanceKlass* ik = k();
1153       ON_KLASS_CREATION(ik, parser, THREAD);
1154       k = instanceKlassHandle(ik);
1155     }
1156 #endif
1157 
1158     // Add class just loaded
1159     // If a class loader supports parallel classloading handle parallel define requests
1160     // find_or_define_instance_class may return a different InstanceKlass
1161     if (is_parallelCapable(class_loader)) {
1162       k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1163     } else {
1164       define_instance_class(k, THREAD);
1165     }
1166   }
1167 
1168   // Make sure we have an entry in the SystemDictionary on success
1169   debug_only( {
1170     if (!HAS_PENDING_EXCEPTION) {
1171       assert(parsed_name != NULL, "parsed_name is still null?");
1172       Symbol*  h_name    = k->name();
1173       ClassLoaderData *defining_loader_data = k->class_loader_data();
1174 
1175       MutexLocker mu(SystemDictionary_lock, THREAD);
1176 
1177       Klass* check = find_class(parsed_name, loader_data);
1178       assert(check == k(), "should be present in the dictionary");
1179 
1180       Klass* check2 = find_class(h_name, defining_loader_data);
1181       assert(check == check2, "name inconsistancy in SystemDictionary");
1182     }
1183   } );
1184 
1185   return k();
1186 }
1187 
1188 #if INCLUDE_CDS
1189 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1190                                              int number_of_entries) {
1191   assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1192          "bad shared dictionary size.");
1193   _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1194 }
1195 
1196 
1197 // If there is a shared dictionary, then find the entry for the
1198 // given shared system class, if any.
1199 
1200 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1201   if (shared_dictionary() != NULL) {
1202     unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1203     int d_index = shared_dictionary()->hash_to_index(d_hash);
1204 
1205     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1206   } else {
1207     return NULL;
1208   }
1209 }
1210 
1211 
1212 // Load a class from the shared spaces (found through the shared system
1213 // dictionary).  Force the superclass and all interfaces to be loaded.
1214 // Update the class definition to include sibling classes and no
1215 // subclasses (yet).  [Classes in the shared space are not part of the
1216 // object hierarchy until loaded.]
1217 
1218 instanceKlassHandle SystemDictionary::load_shared_class(
1219                  Symbol* class_name, Handle class_loader, TRAPS) {
1220   instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1221   // Make sure we only return the boot class for the NULL classloader.
1222   if (ik.not_null() &&
1223       SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1224     Handle protection_domain;
1225     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1226   }
1227   return instanceKlassHandle();
1228 }
1229 
1230 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1231                                                         Handle class_loader,
1232                                                         Handle protection_domain, TRAPS) {
1233   if (ik.not_null()) {
1234     instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1235     Symbol* class_name = ik->name();
1236 
1237     // Found the class, now load the superclass and interfaces.  If they
1238     // are shared, add them to the main system dictionary and reset
1239     // their hierarchy references (supers, subs, and interfaces).
1240 
1241     if (ik->super() != NULL) {
1242       Symbol*  cn = ik->super()->name();
1243       Klass *s = resolve_super_or_fail(class_name, cn,
1244                                        class_loader, protection_domain, true, CHECK_(nh));
1245       if (s != ik->super()) {
1246         // The dynamically resolved super class is not the same as the one we used during dump time,
1247         // so we cannot use ik.
1248         return nh;
1249       }
1250     }
1251 
1252     Array<Klass*>* interfaces = ik->local_interfaces();
1253     int num_interfaces = interfaces->length();
1254     for (int index = 0; index < num_interfaces; index++) {
1255       Klass* k = interfaces->at(index);
1256 
1257       // Note: can not use InstanceKlass::cast here because
1258       // interfaces' InstanceKlass's C++ vtbls haven't been
1259       // reinitialized yet (they will be once the interface classes
1260       // are loaded)
1261       Symbol*  name  = k->name();
1262       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1263       if (k != i) {
1264         // The dynamically resolved interface class is not the same as the one we used during dump time,
1265         // so we cannot use ik.
1266         return nh;
1267       }
1268     }
1269 
1270     // Adjust methods to recover missing data.  They need addresses for
1271     // interpreter entry points and their default native method address
1272     // must be reset.
1273 
1274     // Updating methods must be done under a lock so multiple
1275     // threads don't update these in parallel
1276     //
1277     // Shared classes are all currently loaded by either the bootstrap or
1278     // internal parallel class loaders, so this will never cause a deadlock
1279     // on a custom class loader lock.
1280 
1281     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1282     {
1283       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1284       check_loader_lock_contention(lockObject, THREAD);
1285       ObjectLocker ol(lockObject, THREAD, true);
1286       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1287     }
1288 
1289     if (TraceClassLoading) {
1290       ResourceMark rm;
1291       tty->print("[Loaded %s", ik->external_name());
1292       tty->print(" from shared objects file");
1293       if (class_loader.not_null()) {
1294         tty->print(" by %s", loader_data->loader_name());
1295       }
1296       tty->print_cr("]");
1297     }
1298 
1299     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1300       // Only dump the classes that can be stored into CDS archive
1301       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1302         ResourceMark rm(THREAD);
1303         classlist_file->print_cr("%s", ik->name()->as_C_string());
1304         classlist_file->flush();
1305       }
1306     }
1307 
1308     // notify a class loaded from shared object
1309     ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
1310                                              true /* shared class */);
1311   }
1312   return ik;
1313 }
1314 #endif // INCLUDE_CDS
1315 
1316 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1317   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1318   if (class_loader.is_null()) {
1319 
1320     // Search the shared system dictionary for classes preloaded into the
1321     // shared spaces.
1322     instanceKlassHandle k;
1323     {
1324 #if INCLUDE_CDS
1325       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1326       k = load_shared_class(class_name, class_loader, THREAD);
1327 #endif
1328     }
1329 
1330     if (k.is_null()) {
1331       // Use VM class loader
1332       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1333       k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1334     }
1335 
1336     // find_or_define_instance_class may return a different InstanceKlass
1337     if (!k.is_null()) {
1338       k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1339     }
1340 
1341 #if INCLUDE_JFR
1342     if (k.is_null() && (class_name == jfr_event_handler_proxy)) {
1343       assert(jfr_event_handler_proxy != NULL, "invariant");
1344       // EventHandlerProxy class is generated dynamically in
1345       // EventHandlerProxyCreator::makeEventHandlerProxyClass
1346       // method, so we generate a Java call from here.
1347       //
1348       // EventHandlerProxy class will finally be defined in
1349       // SystemDictionary::resolve_from_stream method, down
1350       // the call stack. Bootstrap classloader is parallel-capable,
1351       // so no concurrency issues are expected.
1352       CLEAR_PENDING_EXCEPTION;
1353       k = JfrUpcalls::load_event_handler_proxy_class(THREAD);
1354       assert(!k.is_null(), "invariant");
1355     }
1356 #endif
1357 
1358     return k;
1359   } else {
1360     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1361     ResourceMark rm(THREAD);
1362 
1363     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1364     JavaThread* jt = (JavaThread*) THREAD;
1365 
1366     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1367                                ClassLoader::perf_app_classload_selftime(),
1368                                ClassLoader::perf_app_classload_count(),
1369                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1370                                jt->get_thread_stat()->perf_timers_addr(),
1371                                PerfClassTraceTime::CLASS_LOAD);
1372 
1373     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1374     // Translate to external class name format, i.e., convert '/' chars to '.'
1375     Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1376 
1377     JavaValue result(T_OBJECT);
1378 
1379     KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1380 
1381     // Call public unsynchronized loadClass(String) directly for all class loaders
1382     // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1383     // acquire a class-name based lock rather than the class loader object lock.
1384     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1385     // so the call to loadClassInternal() was not required.
1386     //
1387     // UnsyncloadClass flag means both call loadClass(String) and do
1388     // not acquire the class loader lock even for class loaders that are
1389     // not parallelCapable. This was a risky transitional
1390     // flag for diagnostic purposes only. It is risky to call
1391     // custom class loaders without synchronization.
1392     // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1393     // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1394     // Do NOT assume this will be supported in future releases.
1395     //
1396     // Added MustCallLoadClassInternal in case we discover in the field
1397     // a customer that counts on this call
1398     if (MustCallLoadClassInternal && has_loadClassInternal()) {
1399       JavaCalls::call_special(&result,
1400                               class_loader,
1401                               spec_klass,
1402                               vmSymbols::loadClassInternal_name(),
1403                               vmSymbols::string_class_signature(),
1404                               string,
1405                               CHECK_(nh));
1406     } else {
1407       JavaCalls::call_virtual(&result,
1408                               class_loader,
1409                               spec_klass,
1410                               vmSymbols::loadClass_name(),
1411                               vmSymbols::string_class_signature(),
1412                               string,
1413                               CHECK_(nh));
1414     }
1415 
1416     assert(result.get_type() == T_OBJECT, "just checking");
1417     oop obj = (oop) result.get_jobject();
1418 
1419     // Primitive classes return null since forName() can not be
1420     // used to obtain any of the Class objects representing primitives or void
1421     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1422       instanceKlassHandle k =
1423                 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1424       // For user defined Java class loaders, check that the name returned is
1425       // the same as that requested.  This check is done for the bootstrap
1426       // loader when parsing the class file.
1427       if (class_name == k->name()) {
1428         return k;
1429       }
1430     }
1431     // Class is not found or has the wrong name, return NULL
1432     return nh;
1433   }
1434 }
1435 
1436 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1437   EventClassDefine event;
1438   if (event.should_commit()) {
1439     event.set_definedClass(k);
1440     event.set_definingClassLoader(def_cld);
1441     event.commit();
1442   }
1443 }
1444 
1445 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1446 
1447   ClassLoaderData* loader_data = k->class_loader_data();
1448   Handle class_loader_h(THREAD, loader_data->class_loader());
1449 
1450   for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
1451 
1452  // for bootstrap and other parallel classloaders don't acquire lock,
1453  // use placeholder token
1454  // If a parallelCapable class loader calls define_instance_class instead of
1455  // find_or_define_instance_class to get here, we have a timing
1456  // hole with systemDictionary updates and check_constraints
1457  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1458     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1459          compute_loader_lock_object(class_loader_h, THREAD)),
1460          "define called without lock");
1461   }
1462 
1463   // Check class-loading constraints. Throw exception if violation is detected.
1464   // Grabs and releases SystemDictionary_lock
1465   // The check_constraints/find_class call and update_dictionary sequence
1466   // must be "atomic" for a specific class/classloader pair so we never
1467   // define two different instanceKlasses for that class/classloader pair.
1468   // Existing classloaders will call define_instance_class with the
1469   // classloader lock held
1470   // Parallel classloaders will call find_or_define_instance_class
1471   // which will require a token to perform the define class
1472   Symbol*  name_h = k->name();
1473   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1474   int d_index = dictionary()->hash_to_index(d_hash);
1475   check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1476 
1477   // Register class just loaded with class loader (placed in Vector)
1478   // Note we do this before updating the dictionary, as this can
1479   // fail with an OutOfMemoryError (if it does, we will *not* put this
1480   // class in the dictionary and will not update the class hierarchy).
1481   // JVMTI FollowReferences needs to find the classes this way.
1482   if (k->class_loader() != NULL) {
1483     methodHandle m(THREAD, Universe::loader_addClass_method());
1484     JavaValue result(T_VOID);
1485     JavaCallArguments args(class_loader_h);
1486     args.push_oop(Handle(THREAD, k->java_mirror()));
1487     JavaCalls::call(&result, m, &args, CHECK);
1488   }
1489 
1490   // Add the new class. We need recompile lock during update of CHA.
1491   {
1492     unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1493     int p_index = placeholders()->hash_to_index(p_hash);
1494 
1495     MutexLocker mu_r(Compile_lock, THREAD);
1496 
1497     // Add to class hierarchy, initialize vtables, and do possible
1498     // deoptimizations.
1499     add_to_hierarchy(k, CHECK); // No exception, but can block
1500 
1501     // Add to systemDictionary - so other classes can see it.
1502     // Grabs and releases SystemDictionary_lock
1503     update_dictionary(d_index, d_hash, p_index, p_hash,
1504                       k, class_loader_h, THREAD);
1505   }
1506   k->eager_initialize(THREAD);
1507 
1508   // notify jvmti
1509   if (JvmtiExport::should_post_class_load()) {
1510       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1511       JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1512 
1513   }
1514 
1515   post_class_define_event(k(), loader_data);
1516 }
1517 
1518 // Support parallel classloading
1519 // All parallel class loaders, including bootstrap classloader
1520 // lock a placeholder entry for this class/class_loader pair
1521 // to allow parallel defines of different classes for this class loader
1522 // With AllowParallelDefine flag==true, in case they do not synchronize around
1523 // FindLoadedClass/DefineClass, calls, we check for parallel
1524 // loading for them, wait if a defineClass is in progress
1525 // and return the initial requestor's results
1526 // This flag does not apply to the bootstrap classloader.
1527 // With AllowParallelDefine flag==false, call through to define_instance_class
1528 // which will throw LinkageError: duplicate class definition.
1529 // False is the requested default.
1530 // For better performance, the class loaders should synchronize
1531 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1532 // potentially waste time reading and parsing the bytestream.
1533 // Note: VM callers should ensure consistency of k/class_name,class_loader
1534 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1535 
1536   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1537   Symbol*  name_h = k->name(); // passed in class_name may be null
1538   ClassLoaderData* loader_data = class_loader_data(class_loader);
1539 
1540   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1541   int d_index = dictionary()->hash_to_index(d_hash);
1542 
1543 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1544   unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1545   int p_index = placeholders()->hash_to_index(p_hash);
1546   PlaceholderEntry* probe;
1547 
1548   {
1549     MutexLocker mu(SystemDictionary_lock, THREAD);
1550     // First check if class already defined
1551     if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1552       Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1553       if (check != NULL) {
1554         return(instanceKlassHandle(THREAD, check));
1555       }
1556     }
1557 
1558     // Acquire define token for this class/classloader
1559     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1560     // Wait if another thread defining in parallel
1561     // All threads wait - even those that will throw duplicate class: otherwise
1562     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1563     // if other thread has not finished updating dictionary
1564     while (probe->definer() != NULL) {
1565       SystemDictionary_lock->wait();
1566     }
1567     // Only special cases allow parallel defines and can use other thread's results
1568     // Other cases fall through, and may run into duplicate defines
1569     // caught by finding an entry in the SystemDictionary
1570     if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1571         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1572         SystemDictionary_lock->notify_all();
1573 #ifdef ASSERT
1574         Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1575         assert(check != NULL, "definer missed recording success");
1576 #endif
1577         return(instanceKlassHandle(THREAD, probe->instance_klass()));
1578     } else {
1579       // This thread will define the class (even if earlier thread tried and had an error)
1580       probe->set_definer(THREAD);
1581     }
1582   }
1583 
1584   define_instance_class(k, THREAD);
1585 
1586   Handle linkage_exception = Handle(); // null handle
1587 
1588   // definer must notify any waiting threads
1589   {
1590     MutexLocker mu(SystemDictionary_lock, THREAD);
1591     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1592     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1593     if (probe != NULL) {
1594       if (HAS_PENDING_EXCEPTION) {
1595         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1596         CLEAR_PENDING_EXCEPTION;
1597       } else {
1598         probe->set_instance_klass(k());
1599       }
1600       probe->set_definer(NULL);
1601       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1602       SystemDictionary_lock->notify_all();
1603     }
1604   }
1605 
1606   // Can't throw exception while holding lock due to rank ordering
1607   if (linkage_exception() != NULL) {
1608     THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1609   }
1610 
1611   return k;
1612 }
1613 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1614   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1615   if (class_loader.is_null()) {
1616     return Handle(THREAD, _system_loader_lock_obj);
1617   } else {
1618     return class_loader;
1619   }
1620 }
1621 
1622 // This method is added to check how often we have to wait to grab loader
1623 // lock. The results are being recorded in the performance counters defined in
1624 // ClassLoader::_sync_systemLoaderLockContentionRate and
1625 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1626 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1627   if (!UsePerfData) {
1628     return;
1629   }
1630 
1631   assert(!loader_lock.is_null(), "NULL lock object");
1632 
1633   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1634       == ObjectSynchronizer::owner_other) {
1635     // contention will likely happen, so increment the corresponding
1636     // contention counter.
1637     if (loader_lock() == _system_loader_lock_obj) {
1638       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1639     } else {
1640       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1641     }
1642   }
1643 }
1644 
1645 // ----------------------------------------------------------------------------
1646 // Lookup
1647 
1648 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1649                                       Symbol* class_name,
1650                                       ClassLoaderData* loader_data) {
1651   assert_locked_or_safepoint(SystemDictionary_lock);
1652   assert (index == dictionary()->index_for(class_name, loader_data),
1653           "incorrect index?");
1654 
1655   Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1656   return k;
1657 }
1658 
1659 
1660 // Basic find on classes in the midst of being loaded
1661 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1662                                            ClassLoaderData* loader_data) {
1663   assert_locked_or_safepoint(SystemDictionary_lock);
1664   unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1665   int p_index = placeholders()->hash_to_index(p_hash);
1666   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1667 }
1668 
1669 
1670 // Used for assertions and verification only
1671 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1672   #ifndef ASSERT
1673   guarantee(VerifyBeforeGC      ||
1674             VerifyDuringGC      ||
1675             VerifyBeforeExit    ||
1676             VerifyDuringStartup ||
1677             VerifyAfterGC, "too expensive");
1678   #endif
1679   assert_locked_or_safepoint(SystemDictionary_lock);
1680 
1681   // First look in the loaded class array
1682   unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1683   int d_index = dictionary()->hash_to_index(d_hash);
1684   return find_class(d_index, d_hash, class_name, loader_data);
1685 }
1686 
1687 
1688 // Get the next class in the diictionary.
1689 Klass* SystemDictionary::try_get_next_class() {
1690   return dictionary()->try_get_next_class();
1691 }
1692 
1693 
1694 // ----------------------------------------------------------------------------
1695 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1696 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1697 // before a new class is used.
1698 
1699 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1700   assert(k.not_null(), "just checking");
1701   assert_locked_or_safepoint(Compile_lock);
1702 
1703   // Link into hierachy. Make sure the vtables are initialized before linking into
1704   k->append_to_sibling_list();                    // add to superklass/sibling list
1705   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1706   k->set_init_state(InstanceKlass::loaded);
1707   // Now flush all code that depended on old class hierarchy.
1708   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1709   // Also, first reinitialize vtable because it may have gotten out of synch
1710   // while the new class wasn't connected to the class hierarchy.
1711   Universe::flush_dependents_on(k);
1712 }
1713 
1714 // ----------------------------------------------------------------------------
1715 // GC support
1716 
1717 // Following roots during mark-sweep is separated in two phases.
1718 //
1719 // The first phase follows preloaded classes and all other system
1720 // classes, since these will never get unloaded anyway.
1721 //
1722 // The second phase removes (unloads) unreachable classes from the
1723 // system dictionary and follows the remaining classes' contents.
1724 
1725 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1726   roots_oops_do(blk, NULL);
1727 }
1728 
1729 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1730   // Follow all system classes and temporary placeholders in dictionary
1731   dictionary()->always_strong_classes_do(closure);
1732 
1733   // Placeholders. These represent classes we're actively loading.
1734   placeholders()->classes_do(closure);
1735 }
1736 
1737 // Calculate a "good" systemdictionary size based
1738 // on predicted or current loaded classes count
1739 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1740   int newsize = _old_default_sdsize;
1741   if ((classcount > 0)  && !DumpSharedSpaces) {
1742     int desiredsize = classcount/_average_depth_goal;
1743     for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1744          newsize = _primelist[++_sdgeneration]) {
1745       if (desiredsize <=  newsize) {
1746         break;
1747       }
1748     }
1749   }
1750   return newsize;
1751 }
1752 
1753 #ifdef ASSERT
1754 class VerifySDReachableAndLiveClosure : public OopClosure {
1755 private:
1756   BoolObjectClosure* _is_alive;
1757 
1758   template <class T> void do_oop_work(T* p) {
1759     oop obj = oopDesc::load_decode_heap_oop(p);
1760     guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1761   }
1762 
1763 public:
1764   VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1765 
1766   virtual void do_oop(oop* p)       { do_oop_work(p); }
1767   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1768 };
1769 #endif
1770 
1771 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1772 // Note: anonymous classes are not in the SD.
1773 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive, bool clean_alive) {
1774   // First, mark for unload all ClassLoaderData referencing a dead class loader.
1775   bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive, clean_alive);
1776   if (unloading_occurred) {
1777     JFR_ONLY(Jfr::on_unloading_classes();)
1778     dictionary()->do_unloading();
1779     constraints()->purge_loader_constraints();
1780     resolution_errors()->purge_resolution_errors();
1781   }
1782   // Oops referenced by the system dictionary may get unreachable independently
1783   // of the class loader (eg. cached protection domain oops). So we need to
1784   // explicitly unlink them here instead of in Dictionary::do_unloading.
1785   dictionary()->unlink(is_alive);
1786 #ifdef ASSERT
1787   VerifySDReachableAndLiveClosure cl(is_alive);
1788   dictionary()->oops_do(&cl);
1789 #endif
1790   return unloading_occurred;
1791 }
1792 
1793 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1794   strong->do_oop(&_java_system_loader);
1795   strong->do_oop(&_system_loader_lock_obj);
1796   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1797 
1798   // Adjust dictionary
1799   dictionary()->roots_oops_do(strong, weak);
1800 
1801   // Visit extra methods
1802   invoke_method_table()->oops_do(strong);
1803 }
1804 
1805 void SystemDictionary::oops_do(OopClosure* f) {
1806   f->do_oop(&_java_system_loader);
1807   f->do_oop(&_system_loader_lock_obj);
1808   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1809 
1810   // Adjust dictionary
1811   dictionary()->oops_do(f);
1812 
1813   // Visit extra methods
1814   invoke_method_table()->oops_do(f);
1815 }
1816 
1817 // Extended Class redefinition support.
1818 // If one of these classes is replaced, we need to replace it in these places.
1819 // KlassClosure::do_klass should take the address of a class but we can
1820 // change that later.
1821 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1822   for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1823     f->do_klass(_well_known_klasses[k]);
1824   }
1825 
1826   {
1827     for (int i = 0; i < T_VOID+1; i++) {
1828       if (_box_klasses[i] != NULL) {
1829         assert(i >= T_BOOLEAN, "checking");
1830         f->do_klass(_box_klasses[i]);
1831       }
1832     }
1833   }
1834 
1835   FilteredFieldsMap::classes_do(f);
1836 }
1837 
1838 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1839   f->do_klass(_abstract_ownable_synchronizer_klass);
1840 }
1841 
1842 // Just the classes from defining class loaders
1843 // Don't iterate over placeholders
1844 void SystemDictionary::classes_do(void f(Klass*)) {
1845   dictionary()->classes_do(f);
1846 }
1847 
1848 // Added for initialize_itable_for_klass
1849 //   Just the classes from defining class loaders
1850 // Don't iterate over placeholders
1851 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1852   dictionary()->classes_do(f, CHECK);
1853 }
1854 
1855 //   All classes, and their class loaders
1856 // Don't iterate over placeholders
1857 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1858   dictionary()->classes_do(f);
1859 }
1860 
1861 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1862   placeholders()->entries_do(f);
1863 }
1864 
1865 void SystemDictionary::methods_do(void f(Method*)) {
1866   dictionary()->methods_do(f);
1867   invoke_method_table()->methods_do(f);
1868 }
1869 
1870 void SystemDictionary::remove_classes_in_error_state() {
1871   dictionary()->remove_classes_in_error_state();
1872 }
1873 
1874 // ----------------------------------------------------------------------------
1875 // Lazily load klasses
1876 
1877 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1878   assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1879 
1880   // if multiple threads calling this function, only one thread will load
1881   // the class.  The other threads will find the loaded version once the
1882   // class is loaded.
1883   Klass* aos = _abstract_ownable_synchronizer_klass;
1884   if (aos == NULL) {
1885     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1886     // Force a fence to prevent any read before the write completes
1887     OrderAccess::fence();
1888     _abstract_ownable_synchronizer_klass = k;
1889   }
1890 }
1891 
1892 // ----------------------------------------------------------------------------
1893 // Initialization
1894 
1895 void SystemDictionary::initialize(TRAPS) {
1896   // Allocate arrays
1897   assert(dictionary() == NULL,
1898          "SystemDictionary should only be initialized once");
1899   _sdgeneration        = 0;
1900   _dictionary          = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1901   _placeholders        = new PlaceholderTable(_nof_buckets);
1902   _number_of_modifications = 0;
1903   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1904   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1905   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1906 
1907   // Allocate private object used as system class loader lock
1908   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1909   // Initialize basic classes
1910   initialize_preloaded_classes(CHECK);
1911 #if INCLUDE_JFR
1912   jfr_event_handler_proxy = SymbolTable::new_permanent_symbol("jdk/jfr/proxy/internal/EventHandlerProxy", CHECK);
1913 #endif // INCLUDE_JFR
1914 }
1915 
1916 // Compact table of directions on the initialization of klasses:
1917 static const short wk_init_info[] = {
1918   #define WK_KLASS_INIT_INFO(name, symbol, option) \
1919     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1920           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1921       | (int)SystemDictionary::option ),
1922   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1923   #undef WK_KLASS_INIT_INFO
1924   0
1925 };
1926 
1927 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1928   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1929   int  info = wk_init_info[id - FIRST_WKID];
1930   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
1931   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1932   Klass**    klassp = &_well_known_klasses[id];
1933   bool must_load = (init_opt < SystemDictionary::Opt);
1934   if ((*klassp) == NULL) {
1935     if (must_load) {
1936       (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1937     } else {
1938       (*klassp) = resolve_or_null(symbol,       CHECK_0); // load optional klass
1939     }
1940   }
1941   return ((*klassp) != NULL);
1942 }
1943 
1944 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1945   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1946   for (int id = (int)start_id; id < (int)limit_id; id++) {
1947     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1948     int info = wk_init_info[id - FIRST_WKID];
1949     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
1950     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1951 
1952     initialize_wk_klass((WKID)id, opt, CHECK);
1953   }
1954 
1955   // move the starting value forward to the limit:
1956   start_id = limit_id;
1957 }
1958 
1959 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1960   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1961   // Preload commonly used klasses
1962   WKID scan = FIRST_WKID;
1963   // first do Object, then String, Class
1964   if (UseSharedSpaces) {
1965     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1966     // Initialize the constant pool for the Object_class
1967     InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1968     ik->constants()->restore_unshareable_info(CHECK);
1969     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1970   } else {
1971     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1972   }
1973 
1974   // Calculate offsets for String and Class classes since they are loaded and
1975   // can be used after this point.
1976   java_lang_String::compute_offsets();
1977   java_lang_Class::compute_offsets();
1978 
1979   // Fixup mirrors for classes loaded before java.lang.Class.
1980   // These calls iterate over the objects currently in the perm gen
1981   // so calling them at this point is matters (not before when there
1982   // are fewer objects and not later after there are more objects
1983   // in the perm gen.
1984   Universe::initialize_basic_type_mirrors(CHECK);
1985   Universe::fixup_mirrors(CHECK);
1986 
1987   // do a bunch more:
1988   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1989 
1990   // Preload ref klasses and set reference types
1991   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1992   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1993 
1994   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
1995   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1996   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1997   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1998   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1999   InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
2000 
2001   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(ReferenceQueue_klass), scan, CHECK);
2002 
2003   // JSR 292 classes
2004   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2005   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2006   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
2007   if (EnableInvokeDynamic) {
2008     initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
2009   } else {
2010     // Skip the JSR 292 classes, if not enabled.
2011     scan = WKID(jsr292_group_end + 1);
2012   }
2013 
2014   initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
2015 
2016   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2017   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2018   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2019   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2020   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2021   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2022   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2023   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2024   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2025   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2026 
2027   { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2028     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2029     _has_loadClassInternal = (method != NULL);
2030   }
2031   { // Compute whether we should use checkPackageAccess or NOT
2032     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2033     _has_checkPackageAccess = (method != NULL);
2034   }
2035 }
2036 
2037 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2038 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2039 BasicType SystemDictionary::box_klass_type(Klass* k) {
2040   assert(k != NULL, "");
2041   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2042     if (_box_klasses[i] == k)
2043       return (BasicType)i;
2044   }
2045   return T_OBJECT;
2046 }
2047 
2048 // Constraints on class loaders. The details of the algorithm can be
2049 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2050 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2051 // that the system dictionary needs to maintain a set of contraints that
2052 // must be satisfied by all classes in the dictionary.
2053 // if defining is true, then LinkageError if already in systemDictionary
2054 // if initiating loader, then ok if InstanceKlass matches existing entry
2055 
2056 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2057                                          instanceKlassHandle k,
2058                                          Handle class_loader, bool defining,
2059                                          TRAPS) {
2060   const char *linkage_error = NULL;
2061   {
2062     Symbol*  name  = k->name();
2063     ClassLoaderData *loader_data = class_loader_data(class_loader);
2064 
2065     MutexLocker mu(SystemDictionary_lock, THREAD);
2066 
2067     Klass* check = find_class(d_index, d_hash, name, loader_data);
2068     if (check != (Klass*)NULL) {
2069       // if different InstanceKlass - duplicate class definition,
2070       // else - ok, class loaded by a different thread in parallel,
2071       // we should only have found it if it was done loading and ok to use
2072       // system dictionary only holds instance classes, placeholders
2073       // also holds array classes
2074 
2075       assert(check->oop_is_instance(), "noninstance in systemdictionary");
2076       if ((defining == true) || (k() != check)) {
2077         linkage_error = "loader (instance of  %s): attempted  duplicate class "
2078           "definition for name: \"%s\"";
2079       } else {
2080         return;
2081       }
2082     }
2083 
2084 #ifdef ASSERT
2085     Symbol* ph_check = find_placeholder(name, loader_data);
2086     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2087 #endif
2088 
2089     if (linkage_error == NULL) {
2090       if (constraints()->check_or_update(k, class_loader, name) == false) {
2091         linkage_error = "loader constraint violation: loader (instance of %s)"
2092           " previously initiated loading for a different type with name \"%s\"";
2093       }
2094     }
2095   }
2096 
2097   // Throw error now if needed (cannot throw while holding
2098   // SystemDictionary_lock because of rank ordering)
2099 
2100   if (linkage_error) {
2101     ResourceMark rm(THREAD);
2102     const char* class_loader_name = loader_name(class_loader());
2103     char* type_name = k->name()->as_C_string();
2104     size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
2105       strlen(type_name);
2106     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2107     jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
2108     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2109   }
2110 }
2111 
2112 
2113 // Update system dictionary - done after check_constraint and add_to_hierachy
2114 // have been called.
2115 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2116                                          int p_index, unsigned int p_hash,
2117                                          instanceKlassHandle k,
2118                                          Handle class_loader,
2119                                          TRAPS) {
2120   // Compile_lock prevents systemDictionary updates during compilations
2121   assert_locked_or_safepoint(Compile_lock);
2122   Symbol*  name  = k->name();
2123   ClassLoaderData *loader_data = class_loader_data(class_loader);
2124 
2125   {
2126   MutexLocker mu1(SystemDictionary_lock, THREAD);
2127 
2128   // See whether biased locking is enabled and if so set it for this
2129   // klass.
2130   // Note that this must be done past the last potential blocking
2131   // point / safepoint. We enable biased locking lazily using a
2132   // VM_Operation to iterate the SystemDictionary and installing the
2133   // biasable mark word into each InstanceKlass's prototype header.
2134   // To avoid race conditions where we accidentally miss enabling the
2135   // optimization for one class in the process of being added to the
2136   // dictionary, we must not safepoint after the test of
2137   // BiasedLocking::enabled().
2138   if (UseBiasedLocking && BiasedLocking::enabled()) {
2139     // Set biased locking bit for all loaded classes; it will be
2140     // cleared if revocation occurs too often for this type
2141     // NOTE that we must only do this when the class is initally
2142     // defined, not each time it is referenced from a new class loader
2143     if (k->class_loader() == class_loader()) {
2144       k->set_prototype_header(markOopDesc::biased_locking_prototype());
2145     }
2146   }
2147 
2148   // Make a new system dictionary entry.
2149   Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2150   if (sd_check == NULL) {
2151     dictionary()->add_klass(name, loader_data, k);
2152     notice_modification();
2153   }
2154 #ifdef ASSERT
2155   sd_check = find_class(d_index, d_hash, name, loader_data);
2156   assert (sd_check != NULL, "should have entry in system dictionary");
2157   // Note: there may be a placeholder entry: for circularity testing
2158   // or for parallel defines
2159 #endif
2160     SystemDictionary_lock->notify_all();
2161   }
2162 }
2163 
2164 
2165 // Try to find a class name using the loader constraints.  The
2166 // loader constraints might know about a class that isn't fully loaded
2167 // yet and these will be ignored.
2168 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2169                     Symbol* class_name, Handle class_loader, TRAPS) {
2170 
2171   // First see if it has been loaded directly.
2172   // Force the protection domain to be null.  (This removes protection checks.)
2173   Handle no_protection_domain;
2174   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2175                                               no_protection_domain, CHECK_NULL);
2176   if (klass != NULL)
2177     return klass;
2178 
2179   // Now look to see if it has been loaded elsewhere, and is subject to
2180   // a loader constraint that would require this loader to return the
2181   // klass that is already loaded.
2182   if (FieldType::is_array(class_name)) {
2183     // For array classes, their Klass*s are not kept in the
2184     // constraint table. The element Klass*s are.
2185     FieldArrayInfo fd;
2186     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2187     if (t != T_OBJECT) {
2188       klass = Universe::typeArrayKlassObj(t);
2189     } else {
2190       MutexLocker mu(SystemDictionary_lock, THREAD);
2191       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2192     }
2193     // If element class already loaded, allocate array klass
2194     if (klass != NULL) {
2195       klass = klass->array_klass_or_null(fd.dimension());
2196     }
2197   } else {
2198     MutexLocker mu(SystemDictionary_lock, THREAD);
2199     // Non-array classes are easy: simply check the constraint table.
2200     klass = constraints()->find_constrained_klass(class_name, class_loader);
2201   }
2202 
2203   return klass;
2204 }
2205 
2206 
2207 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2208                                              Handle class_loader1,
2209                                              Handle class_loader2,
2210                                              Thread* THREAD) {
2211   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2212   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2213 
2214   Symbol* constraint_name = NULL;
2215   if (!FieldType::is_array(class_name)) {
2216     constraint_name = class_name;
2217   } else {
2218     // For array classes, their Klass*s are not kept in the
2219     // constraint table. The element classes are.
2220     FieldArrayInfo fd;
2221     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2222     // primitive types always pass
2223     if (t != T_OBJECT) {
2224       return true;
2225     } else {
2226       constraint_name = fd.object_key();
2227     }
2228   }
2229   unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2230   int d_index1 = dictionary()->hash_to_index(d_hash1);
2231 
2232   unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2233   int d_index2 = dictionary()->hash_to_index(d_hash2);
2234   {
2235   MutexLocker mu_s(SystemDictionary_lock, THREAD);
2236 
2237   // Better never do a GC while we're holding these oops
2238   No_Safepoint_Verifier nosafepoint;
2239 
2240   Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2241   Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2242   return constraints()->add_entry(constraint_name, klass1, class_loader1,
2243                                   klass2, class_loader2);
2244   }
2245 }
2246 
2247 // Add entry to resolution error table to record the error when the first
2248 // attempt to resolve a reference to a class has failed.
2249 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {
2250   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2251   int index = resolution_errors()->hash_to_index(hash);
2252   {
2253     MutexLocker ml(SystemDictionary_lock, Thread::current());
2254     resolution_errors()->add_entry(index, hash, pool, which, error);
2255   }
2256 }
2257 
2258 // Delete a resolution error for RedefineClasses for a constant pool is going away
2259 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2260   resolution_errors()->delete_entry(pool);
2261 }
2262 
2263 // Lookup resolution error table. Returns error if found, otherwise NULL.
2264 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2265   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2266   int index = resolution_errors()->hash_to_index(hash);
2267   {
2268     MutexLocker ml(SystemDictionary_lock, Thread::current());
2269     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2270     return (entry != NULL) ? entry->error() : (Symbol*)NULL;
2271   }
2272 }
2273 
2274 
2275 // Signature constraints ensure that callers and callees agree about
2276 // the meaning of type names in their signatures.  This routine is the
2277 // intake for constraints.  It collects them from several places:
2278 //
2279 //  * LinkResolver::resolve_method (if check_access is true) requires
2280 //    that the resolving class (the caller) and the defining class of
2281 //    the resolved method (the callee) agree on each type in the
2282 //    method's signature.
2283 //
2284 //  * LinkResolver::resolve_interface_method performs exactly the same
2285 //    checks.
2286 //
2287 //  * LinkResolver::resolve_field requires that the constant pool
2288 //    attempting to link to a field agree with the field's defining
2289 //    class about the type of the field signature.
2290 //
2291 //  * klassVtable::initialize_vtable requires that, when a class
2292 //    overrides a vtable entry allocated by a superclass, that the
2293 //    overriding method (i.e., the callee) agree with the superclass
2294 //    on each type in the method's signature.
2295 //
2296 //  * klassItable::initialize_itable requires that, when a class fills
2297 //    in its itables, for each non-abstract method installed in an
2298 //    itable, the method (i.e., the callee) agree with the interface
2299 //    on each type in the method's signature.
2300 //
2301 // All those methods have a boolean (check_access, checkconstraints)
2302 // which turns off the checks.  This is used from specialized contexts
2303 // such as bootstrapping, dumping, and debugging.
2304 //
2305 // No direct constraint is placed between the class and its
2306 // supertypes.  Constraints are only placed along linked relations
2307 // between callers and callees.  When a method overrides or implements
2308 // an abstract method in a supertype (superclass or interface), the
2309 // constraints are placed as if the supertype were the caller to the
2310 // overriding method.  (This works well, since callers to the
2311 // supertype have already established agreement between themselves and
2312 // the supertype.)  As a result of all this, a class can disagree with
2313 // its supertype about the meaning of a type name, as long as that
2314 // class neither calls a relevant method of the supertype, nor is
2315 // called (perhaps via an override) from the supertype.
2316 //
2317 //
2318 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2319 //
2320 // Make sure all class components (including arrays) in the given
2321 // signature will be resolved to the same class in both loaders.
2322 // Returns the name of the type that failed a loader constraint check, or
2323 // NULL if no constraint failed.  No exception except OOME is thrown.
2324 // Arrays are not added to the loader constraint table, their elements are.
2325 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2326                                                Handle loader1, Handle loader2,
2327                                                bool is_method, TRAPS)  {
2328   // Nothing to do if loaders are the same.
2329   if (loader1() == loader2()) {
2330     return NULL;
2331   }
2332 
2333   SignatureStream sig_strm(signature, is_method);
2334   while (!sig_strm.is_done()) {
2335     if (sig_strm.is_object()) {
2336       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2337       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2338         return sig;
2339       }
2340     }
2341     sig_strm.next();
2342   }
2343   return NULL;
2344 }
2345 
2346 
2347 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2348                                                             Symbol* signature,
2349                                                             TRAPS) {
2350   methodHandle empty;
2351   assert(EnableInvokeDynamic, "");
2352   assert(MethodHandles::is_signature_polymorphic(iid) &&
2353          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2354          iid != vmIntrinsics::_invokeGeneric,
2355          err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));
2356 
2357   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2358   int          index = invoke_method_table()->hash_to_index(hash);
2359   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2360   methodHandle m;
2361   if (spe == NULL || spe->method() == NULL) {
2362     spe = NULL;
2363     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2364     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2365     if (!Arguments::is_interpreter_only()) {
2366       // Generate a compiled form of the MH intrinsic.
2367       AdapterHandlerLibrary::create_native_wrapper(m);
2368       // Check if have the compiled code.
2369       if (!m->has_compiled_code()) {
2370         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2371                    "out of space in CodeCache for method handle intrinsic", empty);
2372       }
2373     }
2374     // Now grab the lock.  We might have to throw away the new method,
2375     // if a racing thread has managed to install one at the same time.
2376     {
2377       MutexLocker ml(SystemDictionary_lock, THREAD);
2378       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2379       if (spe == NULL)
2380         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2381       if (spe->method() == NULL)
2382         spe->set_method(m());
2383     }
2384   }
2385 
2386   assert(spe != NULL && spe->method() != NULL, "");
2387   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2388          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2389          "MH intrinsic invariant");
2390   return spe->method();
2391 }
2392 
2393 // Helper for unpacking the return value from linkMethod and linkCallSite.
2394 static methodHandle unpack_method_and_appendix(Handle mname,
2395                                                KlassHandle accessing_klass,
2396                                                objArrayHandle appendix_box,
2397                                                Handle* appendix_result,
2398                                                TRAPS) {
2399   methodHandle empty;
2400   if (mname.not_null()) {
2401     Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2402     if (vmtarget != NULL && vmtarget->is_method()) {
2403       Method* m = (Method*)vmtarget;
2404       oop appendix = appendix_box->obj_at(0);
2405       if (TraceMethodHandles) {
2406     #ifndef PRODUCT
2407         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2408         m->print();
2409         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2410         tty->cr();
2411     #endif //PRODUCT
2412       }
2413       (*appendix_result) = Handle(THREAD, appendix);
2414       // the target is stored in the cpCache and if a reference to this
2415       // MethodName is dropped we need a way to make sure the
2416       // class_loader containing this method is kept alive.
2417       // FIXME: the appendix might also preserve this dependency.
2418       ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2419       this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2420       return methodHandle(THREAD, m);
2421     }
2422   }
2423   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2424   return empty;
2425 }
2426 
2427 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2428                                                           Symbol* signature,
2429                                                           KlassHandle accessing_klass,
2430                                                           Handle *appendix_result,
2431                                                           Handle *method_type_result,
2432                                                           TRAPS) {
2433   methodHandle empty;
2434   assert(EnableInvokeDynamic, "");
2435   assert(!THREAD->is_Compiler_thread(), "");
2436   Handle method_type =
2437     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2438 
2439   KlassHandle  mh_klass = SystemDictionary::MethodHandle_klass();
2440   int ref_kind = JVM_REF_invokeVirtual;
2441   Handle name_str = StringTable::intern(name, CHECK_(empty));
2442   objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2443   assert(appendix_box->obj_at(0) == NULL, "");
2444 
2445   // This should not happen.  JDK code should take care of that.
2446   if (accessing_klass.is_null() || method_type.is_null()) {
2447     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2448   }
2449 
2450   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2451   JavaCallArguments args;
2452   args.push_oop(accessing_klass()->java_mirror());
2453   args.push_int(ref_kind);
2454   args.push_oop(mh_klass()->java_mirror());
2455   args.push_oop(name_str());
2456   args.push_oop(method_type());
2457   args.push_oop(appendix_box());
2458   JavaValue result(T_OBJECT);
2459   JavaCalls::call_static(&result,
2460                          SystemDictionary::MethodHandleNatives_klass(),
2461                          vmSymbols::linkMethod_name(),
2462                          vmSymbols::linkMethod_signature(),
2463                          &args, CHECK_(empty));
2464   Handle mname(THREAD, (oop) result.get_jobject());
2465   (*method_type_result) = method_type;
2466   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2467 }
2468 
2469 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2470 // We must ensure that all class loaders everywhere will reach this class, for any client.
2471 // This is a safe bet for public classes in java.lang, such as Object and String.
2472 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2473 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2474 static bool is_always_visible_class(oop mirror) {
2475   Klass* klass = java_lang_Class::as_Klass(mirror);
2476   if (klass->oop_is_objArray()) {
2477     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2478   }
2479   if (klass->oop_is_typeArray()) {
2480     return true; // primitive array
2481   }
2482   assert(klass->oop_is_instance(), klass->external_name());
2483   return klass->is_public() &&
2484          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2485           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2486 }
2487 
2488 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2489 // signature, as interpreted relative to the given class loader.
2490 // Because of class loader constraints, all method handle usage must be
2491 // consistent with this loader.
2492 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2493                                                  KlassHandle accessing_klass,
2494                                                  TRAPS) {
2495   Handle empty;
2496   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2497   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2498   int          index = invoke_method_table()->hash_to_index(hash);
2499   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2500   if (spe != NULL && spe->method_type() != NULL) {
2501     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2502     return Handle(THREAD, spe->method_type());
2503   } else if (THREAD->is_Compiler_thread()) {
2504     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2505     return Handle();  // do not attempt from within compiler, unless it was cached
2506   }
2507 
2508   Handle class_loader, protection_domain;
2509   if (accessing_klass.not_null()) {
2510     class_loader      = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2511     protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2512   }
2513   bool can_be_cached = true;
2514   int npts = ArgumentCount(signature).size();
2515   objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2516   int arg = 0;
2517   Handle rt; // the return type from the signature
2518   ResourceMark rm(THREAD);
2519   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2520     oop mirror = NULL;
2521     if (can_be_cached) {
2522       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2523       mirror = ss.as_java_mirror(Handle(), Handle(),
2524                                  SignatureStream::ReturnNull, CHECK_(empty));
2525       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2526         // Fall back to accessing_klass context.
2527         can_be_cached = false;
2528       }
2529     }
2530     if (!can_be_cached) {
2531       // Resolve, throwing a real error if it doesn't work.
2532       mirror = ss.as_java_mirror(class_loader, protection_domain,
2533                                  SignatureStream::NCDFError, CHECK_(empty));
2534     }
2535     assert(!oopDesc::is_null(mirror), ss.as_symbol(THREAD)->as_C_string());
2536     if (ss.at_return_type())
2537       rt = Handle(THREAD, mirror);
2538     else
2539       pts->obj_at_put(arg++, mirror);
2540 
2541     // Check accessibility.
2542     if (ss.is_object() && accessing_klass.not_null()) {
2543       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2544       mirror = NULL;  // safety
2545       // Emulate ConstantPool::verify_constant_pool_resolve.
2546       if (sel_klass->oop_is_objArray())
2547         sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2548       if (sel_klass->oop_is_instance()) {
2549         KlassHandle sel_kh(THREAD, sel_klass);
2550         LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2551       }
2552     }
2553   }
2554   assert(arg == npts, "");
2555 
2556   // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2557   JavaCallArguments args(Handle(THREAD, rt()));
2558   args.push_oop(pts());
2559   JavaValue result(T_OBJECT);
2560   JavaCalls::call_static(&result,
2561                          SystemDictionary::MethodHandleNatives_klass(),
2562                          vmSymbols::findMethodHandleType_name(),
2563                          vmSymbols::findMethodHandleType_signature(),
2564                          &args, CHECK_(empty));
2565   Handle method_type(THREAD, (oop) result.get_jobject());
2566 
2567   if (can_be_cached) {
2568     // We can cache this MethodType inside the JVM.
2569     MutexLocker ml(SystemDictionary_lock, THREAD);
2570     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2571     if (spe == NULL)
2572       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2573     if (spe->method_type() == NULL) {
2574       spe->set_method_type(method_type());
2575     }
2576   }
2577 
2578   // report back to the caller with the MethodType
2579   return method_type;
2580 }
2581 
2582 // Ask Java code to find or construct a method handle constant.
2583 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2584                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2585                                                      KlassHandle callee,
2586                                                      Symbol* name_sym,
2587                                                      Symbol* signature,
2588                                                      TRAPS) {
2589   Handle empty;
2590   Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2591   Handle type;
2592   if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2593     type = find_method_handle_type(signature, caller, CHECK_(empty));
2594   } else if (caller.is_null()) {
2595     // This should not happen.  JDK code should take care of that.
2596     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2597   } else {
2598     ResourceMark rm(THREAD);
2599     SignatureStream ss(signature, false);
2600     if (!ss.is_done()) {
2601       oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2602                                      SignatureStream::NCDFError, CHECK_(empty));
2603       type = Handle(THREAD, mirror);
2604       ss.next();
2605       if (!ss.is_done())  type = Handle();  // error!
2606     }
2607   }
2608   if (type.is_null()) {
2609     THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2610   }
2611 
2612   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2613   JavaCallArguments args;
2614   args.push_oop(caller->java_mirror());  // the referring class
2615   args.push_int(ref_kind);
2616   args.push_oop(callee->java_mirror());  // the target class
2617   args.push_oop(name());
2618   args.push_oop(type());
2619   JavaValue result(T_OBJECT);
2620   JavaCalls::call_static(&result,
2621                          SystemDictionary::MethodHandleNatives_klass(),
2622                          vmSymbols::linkMethodHandleConstant_name(),
2623                          vmSymbols::linkMethodHandleConstant_signature(),
2624                          &args, CHECK_(empty));
2625   return Handle(THREAD, (oop) result.get_jobject());
2626 }
2627 
2628 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2629 // name and signature, as interpreted relative to the given class loader.
2630 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2631                                                               Handle bootstrap_specifier,
2632                                                               Symbol* name,
2633                                                               Symbol* type,
2634                                                               Handle *appendix_result,
2635                                                               Handle *method_type_result,
2636                                                               TRAPS) {
2637   methodHandle empty;
2638   Handle bsm, info;
2639   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2640     bsm = bootstrap_specifier;
2641   } else {
2642     assert(bootstrap_specifier->is_objArray(), "");
2643     objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2644     int len = args->length();
2645     assert(len >= 1, "");
2646     bsm = Handle(THREAD, args->obj_at(0));
2647     if (len > 1) {
2648       objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2649       for (int i = 1; i < len; i++)
2650         args1->obj_at_put(i-1, args->obj_at(i));
2651       info = Handle(THREAD, args1);
2652     }
2653   }
2654   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2655             "caller must supply a valid BSM");
2656 
2657   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2658   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2659 
2660   // This should not happen.  JDK code should take care of that.
2661   if (caller.is_null() || method_type.is_null()) {
2662     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2663   }
2664 
2665   objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2666   assert(appendix_box->obj_at(0) == NULL, "");
2667 
2668   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2669   JavaCallArguments args;
2670   args.push_oop(caller->java_mirror());
2671   args.push_oop(bsm());
2672   args.push_oop(method_name());
2673   args.push_oop(method_type());
2674   args.push_oop(info());
2675   args.push_oop(appendix_box);
2676   JavaValue result(T_OBJECT);
2677   JavaCalls::call_static(&result,
2678                          SystemDictionary::MethodHandleNatives_klass(),
2679                          vmSymbols::linkCallSite_name(),
2680                          vmSymbols::linkCallSite_signature(),
2681                          &args, CHECK_(empty));
2682   Handle mname(THREAD, (oop) result.get_jobject());
2683   (*method_type_result) = method_type;
2684   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2685 }
2686 
2687 // Since the identity hash code for symbols changes when the symbols are
2688 // moved from the regular perm gen (hash in the mark word) to the shared
2689 // spaces (hash is the address), the classes loaded into the dictionary
2690 // may be in the wrong buckets.
2691 
2692 void SystemDictionary::reorder_dictionary() {
2693   dictionary()->reorder_dictionary();
2694 }
2695 
2696 
2697 void SystemDictionary::copy_buckets(char** top, char* end) {
2698   dictionary()->copy_buckets(top, end);
2699 }
2700 
2701 
2702 void SystemDictionary::copy_table(char** top, char* end) {
2703   dictionary()->copy_table(top, end);
2704 }
2705 
2706 
2707 void SystemDictionary::reverse() {
2708   dictionary()->reverse();
2709 }
2710 
2711 int SystemDictionary::number_of_classes() {
2712   return dictionary()->number_of_entries();
2713 }
2714 
2715 
2716 // ----------------------------------------------------------------------------
2717 void SystemDictionary::print_shared(bool details) {
2718   shared_dictionary()->print(details);
2719 }
2720 
2721 void SystemDictionary::print(bool details) {
2722   dictionary()->print(details);
2723 
2724   // Placeholders
2725   GCMutexLocker mu(SystemDictionary_lock);
2726   placeholders()->print();
2727 
2728   // loader constraints - print under SD_lock
2729   constraints()->print();
2730 }
2731 
2732 
2733 void SystemDictionary::verify() {
2734   guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2735   guarantee(constraints() != NULL,
2736             "Verify of loader constraints failed");
2737   guarantee(dictionary()->number_of_entries() >= 0 &&
2738             placeholders()->number_of_entries() >= 0,
2739             "Verify of system dictionary failed");
2740 
2741   // Verify dictionary
2742   dictionary()->verify();
2743 
2744   GCMutexLocker mu(SystemDictionary_lock);
2745   placeholders()->verify();
2746 
2747   // Verify constraint table
2748   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2749   constraints()->verify(dictionary(), placeholders());
2750 }
2751 
2752 #ifndef PRODUCT
2753 
2754 // statistics code
2755 class ClassStatistics: AllStatic {
2756  private:
2757   static int nclasses;        // number of classes
2758   static int nmethods;        // number of methods
2759   static int nmethoddata;     // number of methodData
2760   static int class_size;      // size of class objects in words
2761   static int method_size;     // size of method objects in words
2762   static int debug_size;      // size of debug info in methods
2763   static int methoddata_size; // size of methodData objects in words
2764 
2765   static void do_class(Klass* k) {
2766     nclasses++;
2767     class_size += k->size();
2768     if (k->oop_is_instance()) {
2769       InstanceKlass* ik = (InstanceKlass*)k;
2770       class_size += ik->methods()->size();
2771       class_size += ik->constants()->size();
2772       class_size += ik->local_interfaces()->size();
2773       class_size += ik->transitive_interfaces()->size();
2774       // We do not have to count implementors, since we only store one!
2775       // SSS: How should these be accounted now that they have moved?
2776       // class_size += ik->fields()->length();
2777     }
2778   }
2779 
2780   static void do_method(Method* m) {
2781     nmethods++;
2782     method_size += m->size();
2783     // class loader uses same objArray for empty vectors, so don't count these
2784     if (m->has_stackmap_table()) {
2785       method_size += m->stackmap_data()->size();
2786     }
2787 
2788     MethodData* mdo = m->method_data();
2789     if (mdo != NULL) {
2790       nmethoddata++;
2791       methoddata_size += mdo->size();
2792     }
2793   }
2794 
2795  public:
2796   static void print() {
2797     SystemDictionary::classes_do(do_class);
2798     SystemDictionary::methods_do(do_method);
2799     tty->print_cr("Class statistics:");
2800     tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2801     tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2802                   (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2803     tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2804   }
2805 };
2806 
2807 
2808 int ClassStatistics::nclasses        = 0;
2809 int ClassStatistics::nmethods        = 0;
2810 int ClassStatistics::nmethoddata     = 0;
2811 int ClassStatistics::class_size      = 0;
2812 int ClassStatistics::method_size     = 0;
2813 int ClassStatistics::debug_size      = 0;
2814 int ClassStatistics::methoddata_size = 0;
2815 
2816 void SystemDictionary::print_class_statistics() {
2817   ResourceMark rm;
2818   ClassStatistics::print();
2819 }
2820 
2821 
2822 class MethodStatistics: AllStatic {
2823  public:
2824   enum {
2825     max_parameter_size = 10
2826   };
2827  private:
2828 
2829   static int _number_of_methods;
2830   static int _number_of_final_methods;
2831   static int _number_of_static_methods;
2832   static int _number_of_native_methods;
2833   static int _number_of_synchronized_methods;
2834   static int _number_of_profiled_methods;
2835   static int _number_of_bytecodes;
2836   static int _parameter_size_profile[max_parameter_size];
2837   static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2838 
2839   static void initialize() {
2840     _number_of_methods        = 0;
2841     _number_of_final_methods  = 0;
2842     _number_of_static_methods = 0;
2843     _number_of_native_methods = 0;
2844     _number_of_synchronized_methods = 0;
2845     _number_of_profiled_methods = 0;
2846     _number_of_bytecodes      = 0;
2847     for (int i = 0; i < max_parameter_size             ; i++) _parameter_size_profile[i] = 0;
2848     for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile     [j] = 0;
2849   };
2850 
2851   static void do_method(Method* m) {
2852     _number_of_methods++;
2853     // collect flag info
2854     if (m->is_final()       ) _number_of_final_methods++;
2855     if (m->is_static()      ) _number_of_static_methods++;
2856     if (m->is_native()      ) _number_of_native_methods++;
2857     if (m->is_synchronized()) _number_of_synchronized_methods++;
2858     if (m->method_data() != NULL) _number_of_profiled_methods++;
2859     // collect parameter size info (add one for receiver, if any)
2860     _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2861     // collect bytecodes info
2862     {
2863       Thread *thread = Thread::current();
2864       HandleMark hm(thread);
2865       BytecodeStream s(methodHandle(thread, m));
2866       Bytecodes::Code c;
2867       while ((c = s.next()) >= 0) {
2868         _number_of_bytecodes++;
2869         _bytecodes_profile[c]++;
2870       }
2871     }
2872   }
2873 
2874  public:
2875   static void print() {
2876     initialize();
2877     SystemDictionary::methods_do(do_method);
2878     // generate output
2879     tty->cr();
2880     tty->print_cr("Method statistics (static):");
2881     // flag distribution
2882     tty->cr();
2883     tty->print_cr("%6d final        methods  %6.1f%%", _number_of_final_methods       , _number_of_final_methods        * 100.0F / _number_of_methods);
2884     tty->print_cr("%6d static       methods  %6.1f%%", _number_of_static_methods      , _number_of_static_methods       * 100.0F / _number_of_methods);
2885     tty->print_cr("%6d native       methods  %6.1f%%", _number_of_native_methods      , _number_of_native_methods       * 100.0F / _number_of_methods);
2886     tty->print_cr("%6d synchronized methods  %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2887     tty->print_cr("%6d profiled     methods  %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2888     // parameter size profile
2889     tty->cr();
2890     { int tot = 0;
2891       int avg = 0;
2892       for (int i = 0; i < max_parameter_size; i++) {
2893         int n = _parameter_size_profile[i];
2894         tot += n;
2895         avg += n*i;
2896         tty->print_cr("parameter size = %1d: %6d methods  %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2897       }
2898       assert(tot == _number_of_methods, "should be the same");
2899       tty->print_cr("                    %6d methods  100.0%%", _number_of_methods);
2900       tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2901     }
2902     // bytecodes profile
2903     tty->cr();
2904     { int tot = 0;
2905       for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2906         if (Bytecodes::is_defined(i)) {
2907           Bytecodes::Code c = Bytecodes::cast(i);
2908           int n = _bytecodes_profile[c];
2909           tot += n;
2910           tty->print_cr("%9d  %7.3f%%  %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2911         }
2912       }
2913       assert(tot == _number_of_bytecodes, "should be the same");
2914       tty->print_cr("%9d  100.000%%", _number_of_bytecodes);
2915     }
2916     tty->cr();
2917   }
2918 };
2919 
2920 int MethodStatistics::_number_of_methods;
2921 int MethodStatistics::_number_of_final_methods;
2922 int MethodStatistics::_number_of_static_methods;
2923 int MethodStatistics::_number_of_native_methods;
2924 int MethodStatistics::_number_of_synchronized_methods;
2925 int MethodStatistics::_number_of_profiled_methods;
2926 int MethodStatistics::_number_of_bytecodes;
2927 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2928 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2929 
2930 
2931 void SystemDictionary::print_method_statistics() {
2932   MethodStatistics::print();
2933 }
2934 
2935 #endif // PRODUCT