Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "classfile/classLoaderData.inline.hpp"

 #include "classfile/dictionary.hpp"

 #include "classfile/javaClasses.hpp"

 #include "classfile/loaderConstraints.hpp"

 #include "classfile/placeholders.hpp"

 #include "classfile/resolutionErrors.hpp"

 #include "classfile/systemDictionary.hpp"

 #if INCLUDE_CDS

 #include "classfile/sharedClassUtil.hpp"

 #include "classfile/systemDictionaryShared.hpp"

 #endif

 #include "classfile/vmSymbols.hpp"

 #include "compiler/compileBroker.hpp"

 #include "interpreter/bytecodeStream.hpp"

 #include "interpreter/interpreter.hpp"

 #include "jfr/jfrEvents.hpp"

 #include "memory/filemap.hpp"

 #include "memory/gcLocker.hpp"

 #include "memory/oopFactory.hpp"

 #include "oops/instanceKlass.hpp"

 #include "oops/instanceRefKlass.hpp"

 #include "oops/klass.inline.hpp"

 #include "oops/methodData.hpp"

 #include "oops/objArrayKlass.hpp"

 #include "oops/oop.inline.hpp"

 #include "oops/oop.inline2.hpp"

 #include "oops/typeArrayKlass.hpp"

 #include "prims/jvmtiEnvBase.hpp"

 #include "prims/methodHandles.hpp"

 #include "runtime/arguments.hpp"

 #include "runtime/biasedLocking.hpp"

 #include "runtime/fieldType.hpp"

 #include "runtime/handles.inline.hpp"

 #include "runtime/java.hpp"

 #include "runtime/javaCalls.hpp"

 #include "runtime/mutexLocker.hpp"

 #include "runtime/orderAccess.inline.hpp"

 #include "runtime/signature.hpp"

 #include "services/classLoadingService.hpp"

 #include "services/threadService.hpp"

 #include "utilities/macros.hpp"

 #include "utilities/ticks.hpp"

 Dictionary*            SystemDictionary::_dictionary          = NULL;

 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;

 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;

 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;

 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;

 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;

 int         SystemDictionary::_number_of_modifications = 0;

 int         SystemDictionary::_sdgeneration               = 0;

 const int   SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,

               20201,40423,99991};

 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;

 Klass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]

                                                           =  { NULL /*, NULL...*/ };

 Klass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };

 oop         SystemDictionary::_java_system_loader         =  NULL;

 bool        SystemDictionary::_has_loadClassInternal      =  false;

 bool        SystemDictionary::_has_checkPackageAccess     =  false;

 // lazily initialized klass variables

 Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;

 // ----------------------------------------------------------------------------

 // Java-level SystemLoader

 oop SystemDictionary::java_system_loader() {

   return _java_system_loader;

 }

 void SystemDictionary::compute_java_system_loader(TRAPS) {

   KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));

   JavaValue result(T_OBJECT);

   JavaCalls::call_static(&result,

                          KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),

                          vmSymbols::getSystemClassLoader_name(),

                          vmSymbols::void_classloader_signature(),

                          CHECK);

   _java_system_loader = (oop)result.get_jobject();

   CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)

 }

 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {

   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();

   return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);

 }

 // ----------------------------------------------------------------------------

 // debugging

 #ifdef ASSERT

 // return true if class_name contains no '.' (internal format is '/')

 bool SystemDictionary::is_internal_format(Symbol* class_name) {

   if (class_name != NULL) {

     ResourceMark rm;

     char* name = class_name->as_C_string();

     return strchr(name, '.') == NULL;

   } else {

     return true;

   }

 }

 #endif

 #if INCLUDE_JFR

 #include "jfr/jfr.hpp"

 #endif

 // ----------------------------------------------------------------------------

 // Parallel class loading check

 bool SystemDictionary::is_parallelCapable(Handle class_loader) {

   if (UnsyncloadClass || class_loader.is_null()) return true;

   if (AlwaysLockClassLoader) return false;

   return java_lang_ClassLoader::parallelCapable(class_loader());

 }

 // ----------------------------------------------------------------------------

 // ParallelDefineClass flag does not apply to bootclass loader

 bool SystemDictionary::is_parallelDefine(Handle class_loader) {

    if (class_loader.is_null()) return false;

    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {

      return true;

    }

    return false;

 }

 /**

  * Returns true if the passed class loader is the extension class loader.

  */

 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {

   if (class_loader.is_null()) {

     return false;

   }

   return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());

 }

 // ----------------------------------------------------------------------------

 // Resolving of classes

 // Forwards to resolve_or_null

 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {

   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);

   if (HAS_PENDING_EXCEPTION || klass == NULL) {

     KlassHandle k_h(THREAD, klass);

     // can return a null klass

     klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);

   }

   return klass;

 }

 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {

   if (HAS_PENDING_EXCEPTION) {

     // If we have a pending exception we forward it to the caller, unless throw_error is true,

     // in which case we have to check whether the pending exception is a ClassNotFoundException,

     // and if so convert it to a NoClassDefFoundError

     // And chain the original ClassNotFoundException

     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {

       ResourceMark rm(THREAD);

       assert(klass_h() == NULL, "Should not have result with exception pending");

       Handle e(THREAD, PENDING_EXCEPTION);

       CLEAR_PENDING_EXCEPTION;

       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);

     } else {

       return NULL;

     }

   }

   // Class not found, throw appropriate error or exception depending on value of throw_error

   if (klass_h() == NULL) {

     ResourceMark rm(THREAD);

     if (throw_error) {

       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());

     } else {

       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());

     }

   }

   return (Klass*)klass_h();

 }

 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,

                                            bool throw_error, TRAPS)

 {

   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);

 }

 // Forwards to resolve_instance_class_or_null

 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {

   assert(!THREAD->is_Compiler_thread(),

          err_msg("can not load classes with compiler thread: class=%s, classloader=%s",

                  class_name->as_C_string(),

                  class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));

   if (FieldType::is_array(class_name)) {

     return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);

   } else if (FieldType::is_obj(class_name)) {

     ResourceMark rm(THREAD);

     // Ignore wrapping L and ;.

     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,

                                    class_name->utf8_length() - 2, CHECK_NULL);

     return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);

   } else {

     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);

   }

 }

 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {

   return resolve_or_null(class_name, Handle(), Handle(), THREAD);

 }

 // Forwards to resolve_instance_class_or_null

 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,

                                                        Handle class_loader,

                                                        Handle protection_domain,

                                                        TRAPS) {

   assert(FieldType::is_array(class_name), "must be array");

   Klass* k = NULL;

   FieldArrayInfo fd;

   // dimension and object_key in FieldArrayInfo are assigned as a side-effect

   // of this call

   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);

   if (t == T_OBJECT) {

     // naked oop "k" is OK here -- we assign back into it

     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),

                                                          class_loader,

                                                          protection_domain,

                                                          CHECK_NULL);

     if (k != NULL) {

       k = k->array_klass(fd.dimension(), CHECK_NULL);

     }

   } else {

     k = Universe::typeArrayKlassObj(t);

     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);

   }

   return k;

 }

 // Must be called for any super-class or super-interface resolution

 // during class definition to allow class circularity checking

 // super-interface callers:

 //    parse_interfaces - for defineClass & jvmtiRedefineClasses

 // super-class callers:

 //   ClassFileParser - for defineClass & jvmtiRedefineClasses

 //   load_shared_class - while loading a class from shared archive

 //   resolve_instance_class_or_null:

 //     via: handle_parallel_super_load

 //      when resolving a class that has an existing placeholder with

 //      a saved superclass [i.e. a defineClass is currently in progress]

 //      if another thread is trying to resolve the class, it must do

 //      super-class checks on its own thread to catch class circularity

 // This last call is critical in class circularity checking for cases

 // where classloading is delegated to different threads and the

 // classloader lock is released.

 // Take the case: Base->Super->Base

 //   1. If thread T1 tries to do a defineClass of class Base

 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)

 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super

 //    so it tries to load Super

 //   3. If we load the class internally, or user classloader uses same thread

 //      loadClassFromxxx or defineClass via parseClassFile Super ...

 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)

 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base

 //      3.4 calls resolve_super_or_fail Base

 //      3.5 finds T1,Base -> throws class circularity

 //OR 4. If T2 tries to resolve Super via defineClass Super ...

 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)

 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)

 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2

 //      4.4 finds T2, Super -> throws class circularity

 // Must be called, even if superclass is null, since this is

 // where the placeholder entry is created which claims this

 // thread is loading this class/classloader.

 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,

                                                  Symbol* class_name,

                                                  Handle class_loader,

                                                  Handle protection_domain,

                                                  bool is_superclass,

                                                  TRAPS) {

   // Double-check, if child class is already loaded, just return super-class,interface

   // Don't add a placedholder if already loaded, i.e. already in system dictionary

   // Make sure there's a placeholder for the *child* before resolving.

   // Used as a claim that this thread is currently loading superclass/classloader

   // Used here for ClassCircularity checks and also for heap verification

   // (every InstanceKlass in the heap needs to be in the system dictionary

   // or have a placeholder).

   // Must check ClassCircularity before checking if super class is already loaded

   //

   // We might not already have a placeholder if this child_name was

   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);

   // the name of the class might not be known until the stream is actually

   // parsed.

   // Bugs 4643874, 4715493

   // compute_hash can have a safepoint

   ClassLoaderData* loader_data = class_loader_data(class_loader);

   unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);

   int d_index = dictionary()->hash_to_index(d_hash);

   unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);

   int p_index = placeholders()->hash_to_index(p_hash);

   // can't throw error holding a lock

   bool child_already_loaded = false;

   bool throw_circularity_error = false;

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     Klass* childk = find_class(d_index, d_hash, child_name, loader_data);

     Klass* quicksuperk;

     // to support // loading: if child done loading, just return superclass

     // if class_name, & class_loader don't match:

     // if initial define, SD update will give LinkageError

     // if redefine: compare_class_versions will give HIERARCHY_CHANGED

     // so we don't throw an exception here.

     // see: nsk redefclass014 & java.lang.instrument Instrument032

     if ((childk != NULL ) && (is_superclass) &&

        ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&

          ((quicksuperk->name() == class_name) &&

             (quicksuperk->class_loader()  == class_loader()))) {

            return quicksuperk;

     } else {

       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);

       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {

           throw_circularity_error = true;

       }

     }

     if (!throw_circularity_error) {

       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);

     }

   }

   if (throw_circularity_error) {

       ResourceMark rm(THREAD);

       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());

   }

 // java.lang.Object should have been found above

   assert(class_name != NULL, "null super class for resolving");

   // Resolve the super class or interface, check results on return

   Klass* superk = SystemDictionary::resolve_or_null(class_name,

                                                  class_loader,

                                                  protection_domain,

                                                  THREAD);

   KlassHandle superk_h(THREAD, superk);

   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up

   // It is no longer necessary to keep the placeholder table alive until update_dictionary

   // or error. GC used to walk the placeholder table as strong roots.

   // The instanceKlass is kept alive because the class loader is on the stack,

   // which keeps the loader_data alive, as well as all instanceKlasses in

   // the loader_data. parseClassFile adds the instanceKlass to loader_data.

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);

     SystemDictionary_lock->notify_all();

   }

   if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {

     // can null superk

     superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));

   }

   return superk_h();

 }

 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,

                                                   Handle class_loader,

                                                   Handle protection_domain,

                                                   TRAPS) {

   if(!has_checkPackageAccess()) return;

   // Now we have to call back to java to check if the initating class has access

   JavaValue result(T_VOID);

   if (TraceProtectionDomainVerification) {

     // Print out trace information

     tty->print_cr("Checking package access");

     tty->print(" - class loader:      "); class_loader()->print_value_on(tty);      tty->cr();

     tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();

     tty->print(" - loading:           "); klass()->print_value_on(tty);             tty->cr();

   }

   KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());

   JavaCalls::call_special(&result,

                          class_loader,

                          system_loader,

                          vmSymbols::checkPackageAccess_name(),

                          vmSymbols::class_protectiondomain_signature(),

                          Handle(THREAD, klass->java_mirror()),

                          protection_domain,

                          THREAD);

   if (TraceProtectionDomainVerification) {

     if (HAS_PENDING_EXCEPTION) {

       tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");

     } else {

      tty->print_cr(" -> granted");

     }

     tty->cr();

   }

   if (HAS_PENDING_EXCEPTION) return;

   // If no exception has been thrown, we have validated the protection domain

   // Insert the protection domain of the initiating class into the set.

   {

     // We recalculate the entry here -- we've called out to java since

     // the last time it was calculated.

     ClassLoaderData* loader_data = class_loader_data(class_loader);

     Symbol*  kn = klass->name();

     unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);

     int d_index = dictionary()->hash_to_index(d_hash);

     MutexLocker mu(SystemDictionary_lock, THREAD);

     {

       // Note that we have an entry, and entries can be deleted only during GC,

       // so we cannot allow GC to occur while we're holding this entry.

       // We're using a No_Safepoint_Verifier to catch any place where we

       // might potentially do a GC at all.

       // Dictionary::do_unloading() asserts that classes in SD are only

       // unloaded at a safepoint. Anonymous classes are not in SD.

       No_Safepoint_Verifier nosafepoint;

       dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,

                                           protection_domain, THREAD);

     }

   }

 }

 // We only get here if this thread finds that another thread

 // has already claimed the placeholder token for the current operation,

 // but that other thread either never owned or gave up the

 // object lock

 // Waits on SystemDictionary_lock to indicate placeholder table updated

 // On return, caller must recheck placeholder table state

 //

 // We only get here if

 //  1) custom classLoader, i.e. not bootstrap classloader

 //  2) UnsyncloadClass not set

 //  3) custom classLoader has broken the class loader objectLock

 //     so another thread got here in parallel

 //

 // lockObject must be held.

 // Complicated dance due to lock ordering:

 // Must first release the classloader object lock to

 // allow initial definer to complete the class definition

 // and to avoid deadlock

 // Reclaim classloader lock object with same original recursion count

 // Must release SystemDictionary_lock after notify, since

 // class loader lock must be claimed before SystemDictionary_lock

 // to prevent deadlocks

 //

 // The notify allows applications that did an untimed wait() on

 // the classloader object lock to not hang.

 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {

   assert_lock_strong(SystemDictionary_lock);

   bool calledholdinglock

       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);

   assert(calledholdinglock,"must hold lock for notify");

   assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");

   ObjectSynchronizer::notifyall(lockObject, THREAD);

   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);

   SystemDictionary_lock->wait();

   SystemDictionary_lock->unlock();

   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);

   SystemDictionary_lock->lock();

 }

 // If the class in is in the placeholder table, class loading is in progress

 // For cases where the application changes threads to load classes, it

 // is critical to ClassCircularity detection that we try loading

 // the superclass on the same thread internally, so we do parallel

 // super class loading here.

 // This also is critical in cases where the original thread gets stalled

 // even in non-circularity situations.

 // Note: must call resolve_super_or_fail even if null super -

 // to force placeholder entry creation for this class for circularity detection

 // Caller must check for pending exception

 // Returns non-null Klass* if other thread has completed load

 // and we are done,

 // If return null Klass* and no pending exception, the caller must load the class

 instanceKlassHandle SystemDictionary::handle_parallel_super_load(

     Symbol* name, Symbol* superclassname, Handle class_loader,

     Handle protection_domain, Handle lockObject, TRAPS) {

   instanceKlassHandle nh = instanceKlassHandle(); // null Handle

   ClassLoaderData* loader_data = class_loader_data(class_loader);

   unsigned int d_hash = dictionary()->compute_hash(name, loader_data);

   int d_index = dictionary()->hash_to_index(d_hash);

   unsigned int p_hash = placeholders()->compute_hash(name, loader_data);

   int p_index = placeholders()->hash_to_index(p_hash);

   // superk is not used, resolve_super called for circularity check only

   // This code is reached in two situations. One if this thread

   // is loading the same class twice (e.g. ClassCircularity, or

   // java.lang.instrument).

   // The second is if another thread started the resolve_super first

   // and has not yet finished.

   // In both cases the original caller will clean up the placeholder

   // entry on error.

   Klass* superk = SystemDictionary::resolve_super_or_fail(name,

                                                           superclassname,

                                                           class_loader,

                                                           protection_domain,

                                                           true,

                                                           CHECK_(nh));

   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete

   // Serial class loaders and bootstrap classloader do wait for superclass loads

  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // Check if classloading completed while we were loading superclass or waiting

     Klass* check = find_class(d_index, d_hash, name, loader_data);

     if (check != NULL) {

       // Klass is already loaded, so just return it

       return(instanceKlassHandle(THREAD, check));

     } else {

       return nh;

     }

   }

   // must loop to both handle other placeholder updates

   // and spurious notifications

   bool super_load_in_progress = true;

   PlaceholderEntry* placeholder;

   while (super_load_in_progress) {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // Check if classloading completed while we were loading superclass or waiting

     Klass* check = find_class(d_index, d_hash, name, loader_data);

     if (check != NULL) {

       // Klass is already loaded, so just return it

       return(instanceKlassHandle(THREAD, check));

     } else {

       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);

       if (placeholder && placeholder->super_load_in_progress() ){

         // Before UnsyncloadClass:

         // We only get here if the application has released the

         // classloader lock when another thread was in the middle of loading a

         // superclass/superinterface for this class, and now

         // this thread is also trying to load this class.

         // To minimize surprises, the first thread that started to

         // load a class should be the one to complete the loading

         // with the classfile it initially expected.

         // This logic has the current thread wait once it has done

         // all the superclass/superinterface loading it can, until

         // the original thread completes the class loading or fails

         // If it completes we will use the resulting InstanceKlass

         // which we will find below in the systemDictionary.

         // We also get here for parallel bootstrap classloader

         if (class_loader.is_null()) {

           SystemDictionary_lock->wait();

         } else {

           double_lock_wait(lockObject, THREAD);

         }

       } else {

         // If not in SD and not in PH, other thread's load must have failed

         super_load_in_progress = false;

       }

     }

   }

   return (nh);

 }

 // utility function for class load event

 static void post_class_load_event(EventClassLoad &event,

                                   instanceKlassHandle k,

                                   Handle initiating_loader) {

 #if INCLUDE_JFR

   if (event.should_commit()) {

     event.set_loadedClass(k());

     event.set_definingClassLoader(k->class_loader_data());

     oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();

     event.set_initiatingClassLoader(class_loader != NULL ?

                                     ClassLoaderData::class_loader_data_or_null(class_loader) :

                                     (ClassLoaderData*)NULL);

     event.commit();

   }

 #endif // INCLUDE_JFR

 }

 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,

                                                         Handle class_loader,

                                                         Handle protection_domain,

                                                         TRAPS) {

   assert(name != NULL && !FieldType::is_array(name) &&

          !FieldType::is_obj(name), "invalid class name");

   EventClassLoad class_load_start_event;

   // UseNewReflection

   // Fix for 4474172; see evaluation for more details

   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));

   ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);

   // Do lookup to see if class already exist and the protection domain

   // has the right access

   // This call uses find which checks protection domain already matches

   // All subsequent calls use find_class, and set has_loaded_class so that

   // before we return a result we call out to java to check for valid protection domain

   // to allow returning the Klass* and add it to the pd_set if it is valid

   unsigned int d_hash = dictionary()->compute_hash(name, loader_data);

   int d_index = dictionary()->hash_to_index(d_hash);

   Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,

                                       protection_domain, THREAD);

   if (probe != NULL) return probe;

   // Non-bootstrap class loaders will call out to class loader and

   // define via jvm/jni_DefineClass which will acquire the

   // class loader object lock to protect against multiple threads

   // defining the class in parallel by accident.

   // This lock must be acquired here so the waiter will find

   // any successful result in the SystemDictionary and not attempt

   // the define

   // ParallelCapable Classloaders and the bootstrap classloader,

   // or all classloaders with UnsyncloadClass do not acquire lock here

   bool DoObjectLock = true;

   if (is_parallelCapable(class_loader)) {

     DoObjectLock = false;

   }

   unsigned int p_hash = placeholders()->compute_hash(name, loader_data);

   int p_index = placeholders()->hash_to_index(p_hash);

   // Class is not in SystemDictionary so we have to do loading.

   // Make sure we are synchronized on the class loader before we proceed

   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);

   check_loader_lock_contention(lockObject, THREAD);

   ObjectLocker ol(lockObject, THREAD, DoObjectLock);

   // Check again (after locking) if class already exist in SystemDictionary

   bool class_has_been_loaded   = false;

   bool super_load_in_progress  = false;

   bool havesupername = false;

   instanceKlassHandle k;

   PlaceholderEntry* placeholder;

   Symbol* superclassname = NULL;

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     Klass* check = find_class(d_index, d_hash, name, loader_data);

     if (check != NULL) {

       // Klass is already loaded, so just return it

       class_has_been_loaded = true;

       k = instanceKlassHandle(THREAD, check);

     } else {

       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);

       if (placeholder && placeholder->super_load_in_progress()) {

          super_load_in_progress = true;

          if (placeholder->havesupername() == true) {

            superclassname = placeholder->supername();

            havesupername = true;

          }

       }

     }

   }

   // If the class is in the placeholder table, class loading is in progress

   if (super_load_in_progress && havesupername==true) {

     k = SystemDictionary::handle_parallel_super_load(name, superclassname,

         class_loader, protection_domain, lockObject, THREAD);

     if (HAS_PENDING_EXCEPTION) {

       return NULL;

     }

     if (!k.is_null()) {

       class_has_been_loaded = true;

     }

   }

   bool throw_circularity_error = false;

   if (!class_has_been_loaded) {

     bool load_instance_added = false;

     // add placeholder entry to record loading instance class

     // Five cases:

     // All cases need to prevent modifying bootclasssearchpath

     // in parallel with a classload of same classname

     // Redefineclasses uses existence of the placeholder for the duration

     // of the class load to prevent concurrent redefinition of not completely

     // defined classes.

     // case 1. traditional classloaders that rely on the classloader object lock

     //   - no other need for LOAD_INSTANCE

     // case 2. traditional classloaders that break the classloader object lock

     //    as a deadlock workaround. Detection of this case requires that

     //    this check is done while holding the classloader object lock,

     //    and that lock is still held when calling classloader's loadClass.

     //    For these classloaders, we ensure that the first requestor

     //    completes the load and other requestors wait for completion.

     // case 3. UnsyncloadClass - don't use objectLocker

     //    With this flag, we allow parallel classloading of a

     //    class/classloader pair

     // case4. Bootstrap classloader - don't own objectLocker

     //    This classloader supports parallelism at the classloader level,

     //    but only allows a single load of a class/classloader pair.

     //    No performance benefit and no deadlock issues.

     // case 5. parallelCapable user level classloaders - without objectLocker

     //    Allow parallel classloading of a class/classloader pair

     {

       MutexLocker mu(SystemDictionary_lock, THREAD);

       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {

         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);

         if (oldprobe) {

           // only need check_seen_thread once, not on each loop

           // 6341374 java/lang/Instrument with -Xcomp

           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {

             throw_circularity_error = true;

           } else {

             // case 1: traditional: should never see load_in_progress.

             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {

               // case 4: bootstrap classloader: prevent futile classloading,

               // wait on first requestor

               if (class_loader.is_null()) {

                 SystemDictionary_lock->wait();

               } else {

               // case 2: traditional with broken classloader lock. wait on first

               // requestor.

                 double_lock_wait(lockObject, THREAD);

               }

               // Check if classloading completed while we were waiting

               Klass* check = find_class(d_index, d_hash, name, loader_data);

               if (check != NULL) {

                 // Klass is already loaded, so just return it

                 k = instanceKlassHandle(THREAD, check);

                 class_has_been_loaded = true;

               }

               // check if other thread failed to load and cleaned up

               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);

             }

           }

         }

       }

       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock

       // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try

       // LOAD_INSTANCE in parallel

       if (!throw_circularity_error && !class_has_been_loaded) {

         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);

         load_instance_added = true;

         // For class loaders that do not acquire the classloader object lock,

         // if they did not catch another thread holding LOAD_INSTANCE,

         // need a check analogous to the acquire ObjectLocker/find_class

         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL

         // one final check if the load has already completed

         // class loaders holding the ObjectLock shouldn't find the class here

         Klass* check = find_class(d_index, d_hash, name, loader_data);

         if (check != NULL) {

         // Klass is already loaded, so return it after checking/adding protection domain

           k = instanceKlassHandle(THREAD, check);

           class_has_been_loaded = true;

         }

       }

     }

     // must throw error outside of owning lock

     if (throw_circularity_error) {

       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");

       ResourceMark rm(THREAD);

       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());

     }

     if (!class_has_been_loaded) {

       // Do actual loading

       k = load_instance_class(name, class_loader, THREAD);

       // For UnsyncloadClass only

       // If they got a linkageError, check if a parallel class load succeeded.

       // If it did, then for bytecode resolution the specification requires

       // that we return the same result we did for the other thread, i.e. the

       // successfully loaded InstanceKlass

       // Should not get here for classloaders that support parallelism

       // with the new cleaner mechanism, even with AllowParallelDefineClass

       // Bootstrap goes through here to allow for an extra guarantee check

       if (UnsyncloadClass || (class_loader.is_null())) {

         if (k.is_null() && HAS_PENDING_EXCEPTION

           && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {

           MutexLocker mu(SystemDictionary_lock, THREAD);

           Klass* check = find_class(d_index, d_hash, name, loader_data);

           if (check != NULL) {

             // Klass is already loaded, so just use it

             k = instanceKlassHandle(THREAD, check);

             CLEAR_PENDING_EXCEPTION;

             guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");

           }

         }

       }

       // If everything was OK (no exceptions, no null return value), and

       // class_loader is NOT the defining loader, do a little more bookkeeping.

       if (!HAS_PENDING_EXCEPTION && !k.is_null() &&

         k->class_loader() != class_loader()) {

         check_constraints(d_index, d_hash, k, class_loader, false, THREAD);

         // Need to check for a PENDING_EXCEPTION again; check_constraints

         // can throw but we may have to remove entry from the placeholder table below.

         if (!HAS_PENDING_EXCEPTION) {

           // Record dependency for non-parent delegation.

           // This recording keeps the defining class loader of the klass (k) found

           // from being unloaded while the initiating class loader is loaded

           // even if the reference to the defining class loader is dropped

           // before references to the initiating class loader.

           loader_data->record_dependency(k(), THREAD);

         }

         if (!HAS_PENDING_EXCEPTION) {

           { // Grabbing the Compile_lock prevents systemDictionary updates

             // during compilations.

             MutexLocker mu(Compile_lock, THREAD);

             update_dictionary(d_index, d_hash, p_index, p_hash,

                               k, class_loader, THREAD);

           }

           if (JvmtiExport::should_post_class_load()) {

             Thread *thread = THREAD;

             assert(thread->is_Java_thread(), "thread->is_Java_thread()");

             JvmtiExport::post_class_load((JavaThread *) thread, k());

           }

         }

       }

     } // load_instance_class loop

     if (load_instance_added == true) {

       // clean up placeholder entries for LOAD_INSTANCE success or error

       // This brackets the SystemDictionary updates for both defining

       // and initiating loaders

       MutexLocker mu(SystemDictionary_lock, THREAD);

       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);

       SystemDictionary_lock->notify_all();

     }

   }

   if (HAS_PENDING_EXCEPTION || k.is_null()) {

     return NULL;

   }

   post_class_load_event(class_load_start_event, k, class_loader);

 #ifdef ASSERT

   {

     ClassLoaderData* loader_data = k->class_loader_data();

     MutexLocker mu(SystemDictionary_lock, THREAD);

     Klass* kk = find_class(name, loader_data);

     assert(kk == k(), "should be present in dictionary");

   }

 #endif

   // return if the protection domain in NULL

   if (protection_domain() == NULL) return k();

   // Check the protection domain has the right access

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // Note that we have an entry, and entries can be deleted only during GC,

     // so we cannot allow GC to occur while we're holding this entry.

     // We're using a No_Safepoint_Verifier to catch any place where we

     // might potentially do a GC at all.

     // Dictionary::do_unloading() asserts that classes in SD are only

     // unloaded at a safepoint. Anonymous classes are not in SD.

     No_Safepoint_Verifier nosafepoint;

     if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,

                                                  loader_data,

                                                  protection_domain)) {

       return k();

     }

   }

   // Verify protection domain. If it fails an exception is thrown

   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);

   return k();

 }

 // This routine does not lock the system dictionary.

 //

 // Since readers don't hold a lock, we must make sure that system

 // dictionary entries are only removed at a safepoint (when only one

 // thread is running), and are added to in a safe way (all links must

 // be updated in an MT-safe manner).

 //

 // Callers should be aware that an entry could be added just after

 // _dictionary->bucket(index) is read here, so the caller will not see

 // the new entry.

 Klass* SystemDictionary::find(Symbol* class_name,

                               Handle class_loader,

                               Handle protection_domain,

                               TRAPS) {

   // UseNewReflection

   // The result of this call should be consistent with the result

   // of the call to resolve_instance_class_or_null().

   // See evaluation 6790209 and 4474172 for more details.

   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));

   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());

   if (loader_data == NULL) {

     // If the ClassLoaderData has not been setup,

     // then the class loader has no entries in the dictionary.

     return NULL;

   }

   unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);

   int d_index = dictionary()->hash_to_index(d_hash);

   {

     // Note that we have an entry, and entries can be deleted only during GC,

     // so we cannot allow GC to occur while we're holding this entry.

     // We're using a No_Safepoint_Verifier to catch any place where we

     // might potentially do a GC at all.

     // Dictionary::do_unloading() asserts that classes in SD are only

     // unloaded at a safepoint. Anonymous classes are not in SD.

     No_Safepoint_Verifier nosafepoint;

     return dictionary()->find(d_index, d_hash, class_name, loader_data,

                               protection_domain, THREAD);

   }

 }

 // Look for a loaded instance or array klass by name.  Do not do any loading.

 // return NULL in case of error.

 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,

                                                       Handle class_loader,

                                                       Handle protection_domain,

                                                       TRAPS) {

   Klass* k = NULL;

   assert(class_name != NULL, "class name must be non NULL");

   if (FieldType::is_array(class_name)) {

     // The name refers to an array.  Parse the name.

     // dimension and object_key in FieldArrayInfo are assigned as a

     // side-effect of this call

     FieldArrayInfo fd;

     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));

     if (t != T_OBJECT) {

       k = Universe::typeArrayKlassObj(t);

     } else {

       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);

     }

     if (k != NULL) {

       k = k->array_klass_or_null(fd.dimension());

     }

   } else {

     k = find(class_name, class_loader, protection_domain, THREAD);

   }

   return k;

 }

 // Note: this method is much like resolve_from_stream, but

 // updates no supplemental data structures.

 // TODO consolidate the two methods with a helper routine?

 Klass* SystemDictionary::parse_stream(Symbol* class_name,

                                       Handle class_loader,

                                       Handle protection_domain,

                                       ClassFileStream* st,

                                       KlassHandle host_klass,

                                       GrowableArray<Handle>* cp_patches,

                                       TRAPS) {

   TempNewSymbol parsed_name = NULL;

   EventClassLoad class_load_start_event;

   ClassLoaderData* loader_data;

   if (host_klass.not_null()) {

     // Create a new CLD for anonymous class, that uses the same class loader

     // as the host_klass

     assert(EnableInvokeDynamic, "");

     guarantee(host_klass->class_loader() == class_loader(), "should be the same");

     guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");

     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);

     loader_data->record_dependency(host_klass(), CHECK_NULL);

   } else {

     loader_data = ClassLoaderData::class_loader_data(class_loader());

   }

   // Parse the stream. Note that we do this even though this klass might

   // already be present in the SystemDictionary, otherwise we would not

   // throw potential ClassFormatErrors.

   //

   // Note: "name" is updated.

   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,

                                                              loader_data,

                                                              protection_domain,

                                                              host_klass,

                                                              cp_patches,

                                                              parsed_name,

                                                              true,

                                                              THREAD);

   if (host_klass.not_null() && k.not_null()) {

     assert(EnableInvokeDynamic, "");

     // If it's anonymous, initialize it now, since nobody else will.

     {

       MutexLocker mu_r(Compile_lock, THREAD);

       // Add to class hierarchy, initialize vtables, and do possible

       // deoptimizations.

       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block

       // But, do not add to system dictionary.

       // compiled code dependencies need to be validated anyway

       notice_modification();

     }

     // Rewrite and patch constant pool here.

     k->link_class(CHECK_NULL);

     if (cp_patches != NULL) {

       k->constants()->patch_resolved_references(cp_patches);

     }

     k->eager_initialize(CHECK_NULL);

     // notify jvmti

     if (JvmtiExport::should_post_class_load()) {

         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");

         JvmtiExport::post_class_load((JavaThread *) THREAD, k());

     }

     post_class_load_event(class_load_start_event, k, class_loader);

   }

   assert(host_klass.not_null() || cp_patches == NULL,

          "cp_patches only found with host_klass");

   return k();

 }

 // Add a klass to the system from a stream (called by jni_DefineClass and

 // JVM_DefineClass).

 // Note: class_name can be NULL. In that case we do not know the name of

 // the class until we have parsed the stream.

 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,

                                              Handle class_loader,

                                              Handle protection_domain,

                                              ClassFileStream* st,

                                              bool verify,

                                              TRAPS) {

   // Classloaders that support parallelism, e.g. bootstrap classloader,

   // or all classloaders with UnsyncloadClass do not acquire lock here

   bool DoObjectLock = true;

   if (is_parallelCapable(class_loader)) {

     DoObjectLock = false;

   }

   ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);

   // Make sure we are synchronized on the class loader before we proceed

   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);

   check_loader_lock_contention(lockObject, THREAD);

   ObjectLocker ol(lockObject, THREAD, DoObjectLock);

   TempNewSymbol parsed_name = NULL;

   // Parse the stream. Note that we do this even though this klass might

   // already be present in the SystemDictionary, otherwise we would not

   // throw potential ClassFormatErrors.

   //

   // Note: "name" is updated.

   ClassFileParser parser(st);

   instanceKlassHandle k = parser.parseClassFile(class_name,

                                                 loader_data,

                                                 protection_domain,

                                                 parsed_name,

                                                 verify,

                                                 THREAD);

   const char* pkg = "java/";

   size_t pkglen = strlen(pkg);

   if (!HAS_PENDING_EXCEPTION &&

       !class_loader.is_null() &&

       parsed_name != NULL &&

       parsed_name->utf8_length() >= (int)pkglen &&

       !strncmp((const char*)parsed_name->bytes(), pkg, pkglen)) {

     // It is illegal to define classes in the "java." package from

     // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader

     ResourceMark rm(THREAD);

     char* name = parsed_name->as_C_string();

     char* index = strrchr(name, '/');

     assert(index != NULL, "must be");

     *index = '\0'; // chop to just the package name

     while ((index = strchr(name, '/')) != NULL) {

       *index = '.'; // replace '/' with '.' in package name

     }

     const char* fmt = "Prohibited package name: %s";

     size_t len = strlen(fmt) + strlen(name);

     char* message = NEW_RESOURCE_ARRAY(char, len);

     jio_snprintf(message, len, fmt, name);

     Exceptions::_throw_msg(THREAD_AND_LOCATION,

       vmSymbols::java_lang_SecurityException(), message);

   }

   if (!HAS_PENDING_EXCEPTION) {

     assert(parsed_name != NULL, "Sanity");

     assert(class_name == NULL || class_name == parsed_name, "name mismatch");

     // Verification prevents us from creating names with dots in them, this

     // asserts that that's the case.

     assert(is_internal_format(parsed_name),

            "external class name format used internally");

 #if INCLUDE_JFR

     {

       InstanceKlass* ik = k();

       ON_KLASS_CREATION(ik, parser, THREAD);

       k = instanceKlassHandle(ik);

     }

 #endif

     // Add class just loaded

     // If a class loader supports parallel classloading handle parallel define requests

     // find_or_define_instance_class may return a different InstanceKlass

     if (is_parallelCapable(class_loader)) {

       k = find_or_define_instance_class(class_name, class_loader, k, THREAD);

     } else {

       define_instance_class(k, THREAD);

     }

   }

   // Make sure we have an entry in the SystemDictionary on success

   debug_only( {

     if (!HAS_PENDING_EXCEPTION) {

       assert(parsed_name != NULL, "parsed_name is still null?");

       Symbol*  h_name    = k->name();

       ClassLoaderData *defining_loader_data = k->class_loader_data();

       MutexLocker mu(SystemDictionary_lock, THREAD);

       Klass* check = find_class(parsed_name, loader_data);

       assert(check == k(), "should be present in the dictionary");

       Klass* check2 = find_class(h_name, defining_loader_data);

       assert(check == check2, "name inconsistancy in SystemDictionary");

     }

   } );

   return k();

 }

 #if INCLUDE_CDS

 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,

                                              int number_of_entries) {

   assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),

          "bad shared dictionary size.");

   _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);

 }

 // If there is a shared dictionary, then find the entry for the

 // given shared system class, if any.

 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {

   if (shared_dictionary() != NULL) {

     unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);

     int d_index = shared_dictionary()->hash_to_index(d_hash);

     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);

   } else {

     return NULL;

   }

 }

 // Load a class from the shared spaces (found through the shared system

 // dictionary).  Force the superclass and all interfaces to be loaded.

 // Update the class definition to include sibling classes and no

 // subclasses (yet).  [Classes in the shared space are not part of the

 // object hierarchy until loaded.]

 instanceKlassHandle SystemDictionary::load_shared_class(

                  Symbol* class_name, Handle class_loader, TRAPS) {

   instanceKlassHandle ik (THREAD, find_shared_class(class_name));

   // Make sure we only return the boot class for the NULL classloader.

   if (ik.not_null() &&

       SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {

     Handle protection_domain;

     return load_shared_class(ik, class_loader, protection_domain, THREAD);

   }

   return instanceKlassHandle();

 }

 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,

                                                         Handle class_loader,

                                                         Handle protection_domain, TRAPS) {

   if (ik.not_null()) {

     instanceKlassHandle nh = instanceKlassHandle(); // null Handle

     Symbol* class_name = ik->name();

     // Found the class, now load the superclass and interfaces.  If they

     // are shared, add them to the main system dictionary and reset

     // their hierarchy references (supers, subs, and interfaces).

     if (ik->super() != NULL) {

       Symbol*  cn = ik->super()->name();

       Klass *s = resolve_super_or_fail(class_name, cn,

                                        class_loader, protection_domain, true, CHECK_(nh));

       if (s != ik->super()) {

         // The dynamically resolved super class is not the same as the one we used during dump time,

         // so we cannot use ik.

         return nh;

       }

     }

     Array<Klass*>* interfaces = ik->local_interfaces();

     int num_interfaces = interfaces->length();

     for (int index = 0; index < num_interfaces; index++) {

       Klass* k = interfaces->at(index);

       // Note: can not use InstanceKlass::cast here because

       // interfaces' InstanceKlass's C++ vtbls haven't been

       // reinitialized yet (they will be once the interface classes

       // are loaded)

       Symbol*  name  = k->name();

       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));

       if (k != i) {

         // The dynamically resolved interface class is not the same as the one we used during dump time,

         // so we cannot use ik.

         return nh;

       }

     }

     // Adjust methods to recover missing data.  They need addresses for

     // interpreter entry points and their default native method address

     // must be reset.

     // Updating methods must be done under a lock so multiple

     // threads don't update these in parallel

     //

     // Shared classes are all currently loaded by either the bootstrap or

     // internal parallel class loaders, so this will never cause a deadlock

     // on a custom class loader lock.

     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());

     {

       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);

       check_loader_lock_contention(lockObject, THREAD);

       ObjectLocker ol(lockObject, THREAD, true);

       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));

     }

     if (TraceClassLoading) {

       ResourceMark rm;

       tty->print("[Loaded %s", ik->external_name());

       tty->print(" from shared objects file");

       if (class_loader.not_null()) {

         tty->print(" by %s", loader_data->loader_name());

       }

       tty->print_cr("]");

     }

     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {

       // Only dump the classes that can be stored into CDS archive

       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {

         ResourceMark rm(THREAD);

         classlist_file->print_cr("%s", ik->name()->as_C_string());

         classlist_file->flush();

       }

     }

     // notify a class loaded from shared object

     ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),

                                              true /* shared class */);

   }

   return ik;

 }

 #endif // INCLUDE_CDS

 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {

   instanceKlassHandle nh = instanceKlassHandle(); // null Handle

   if (class_loader.is_null()) {

     // Search the shared system dictionary for classes preloaded into the

     // shared spaces.

     instanceKlassHandle k;

     {

 #if INCLUDE_CDS

       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());

       k = load_shared_class(class_name, class_loader, THREAD);

 #endif

     }

     if (k.is_null()) {

       // Use VM class loader

       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());

       k = ClassLoader::load_classfile(class_name, CHECK_(nh));

     }

     // find_or_define_instance_class may return a different InstanceKlass

     if (!k.is_null()) {

       k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));

     }

     return k;

   } else {

     // Use user specified class loader to load class. Call loadClass operation on class_loader.

     ResourceMark rm(THREAD);

     assert(THREAD->is_Java_thread(), "must be a JavaThread");

     JavaThread* jt = (JavaThread*) THREAD;

     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),

                                ClassLoader::perf_app_classload_selftime(),

                                ClassLoader::perf_app_classload_count(),

                                jt->get_thread_stat()->perf_recursion_counts_addr(),

                                jt->get_thread_stat()->perf_timers_addr(),

                                PerfClassTraceTime::CLASS_LOAD);

     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));

     // Translate to external class name format, i.e., convert '/' chars to '.'

     Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));

     JavaValue result(T_OBJECT);

     KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());

     // Call public unsynchronized loadClass(String) directly for all class loaders

     // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will

     // acquire a class-name based lock rather than the class loader object lock.

     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),

     // so the call to loadClassInternal() was not required.

     //

     // UnsyncloadClass flag means both call loadClass(String) and do

     // not acquire the class loader lock even for class loaders that are

     // not parallelCapable. This was a risky transitional

     // flag for diagnostic purposes only. It is risky to call

     // custom class loaders without synchronization.

     // WARNING If a custom class loader does NOT synchronizer findClass, or callers of

     // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.

     // Do NOT assume this will be supported in future releases.

     //

     // Added MustCallLoadClassInternal in case we discover in the field

     // a customer that counts on this call

     if (MustCallLoadClassInternal && has_loadClassInternal()) {

       JavaCalls::call_special(&result,

                               class_loader,

                               spec_klass,

                               vmSymbols::loadClassInternal_name(),

                               vmSymbols::string_class_signature(),

                               string,

                               CHECK_(nh));

     } else {

       JavaCalls::call_virtual(&result,

                               class_loader,

                               spec_klass,

                               vmSymbols::loadClass_name(),

                               vmSymbols::string_class_signature(),

                               string,

                               CHECK_(nh));

     }

     assert(result.get_type() == T_OBJECT, "just checking");

     oop obj = (oop) result.get_jobject();

     // Primitive classes return null since forName() can not be

     // used to obtain any of the Class objects representing primitives or void

     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {

       instanceKlassHandle k =

                 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));

       // For user defined Java class loaders, check that the name returned is

       // the same as that requested.  This check is done for the bootstrap

       // loader when parsing the class file.

       if (class_name == k->name()) {

         return k;

       }

     }

     // Class is not found or has the wrong name, return NULL

     return nh;

   }

 }

 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {

   EventClassDefine event;

   if (event.should_commit()) {

     event.set_definedClass(k);

     event.set_definingClassLoader(def_cld);

     event.commit();

   }

 }

 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {

   ClassLoaderData* loader_data = k->class_loader_data();

   Handle class_loader_h(THREAD, loader_data->class_loader());

   for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}

  // for bootstrap and other parallel classloaders don't acquire lock,

  // use placeholder token

  // If a parallelCapable class loader calls define_instance_class instead of

  // find_or_define_instance_class to get here, we have a timing

  // hole with systemDictionary updates and check_constraints

  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {

     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,

          compute_loader_lock_object(class_loader_h, THREAD)),

          "define called without lock");

   }

   // Check class-loading constraints. Throw exception if violation is detected.

   // Grabs and releases SystemDictionary_lock

   // The check_constraints/find_class call and update_dictionary sequence

   // must be "atomic" for a specific class/classloader pair so we never

   // define two different instanceKlasses for that class/classloader pair.

   // Existing classloaders will call define_instance_class with the

   // classloader lock held

   // Parallel classloaders will call find_or_define_instance_class

   // which will require a token to perform the define class

   Symbol*  name_h = k->name();

   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);

   int d_index = dictionary()->hash_to_index(d_hash);

   check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);

   // Register class just loaded with class loader (placed in Vector)

   // Note we do this before updating the dictionary, as this can

   // fail with an OutOfMemoryError (if it does, we will *not* put this

   // class in the dictionary and will not update the class hierarchy).

   // JVMTI FollowReferences needs to find the classes this way.

   if (k->class_loader() != NULL) {

     methodHandle m(THREAD, Universe::loader_addClass_method());

     JavaValue result(T_VOID);

     JavaCallArguments args(class_loader_h);

     args.push_oop(Handle(THREAD, k->java_mirror()));

     JavaCalls::call(&result, m, &args, CHECK);

   }

   // Add the new class. We need recompile lock during update of CHA.

   {

     unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);

     int p_index = placeholders()->hash_to_index(p_hash);

     MutexLocker mu_r(Compile_lock, THREAD);

     // Add to class hierarchy, initialize vtables, and do possible

     // deoptimizations.

     add_to_hierarchy(k, CHECK); // No exception, but can block

     // Add to systemDictionary - so other classes can see it.

     // Grabs and releases SystemDictionary_lock

     update_dictionary(d_index, d_hash, p_index, p_hash,

                       k, class_loader_h, THREAD);

   }

   k->eager_initialize(THREAD);

   // notify jvmti

   if (JvmtiExport::should_post_class_load()) {

       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");

       JvmtiExport::post_class_load((JavaThread *) THREAD, k());

   }

   post_class_define_event(k(), loader_data);

 }

 // Support parallel classloading

 // All parallel class loaders, including bootstrap classloader

 // lock a placeholder entry for this class/class_loader pair

 // to allow parallel defines of different classes for this class loader

 // With AllowParallelDefine flag==true, in case they do not synchronize around

 // FindLoadedClass/DefineClass, calls, we check for parallel

 // loading for them, wait if a defineClass is in progress

 // and return the initial requestor's results

 // This flag does not apply to the bootstrap classloader.

 // With AllowParallelDefine flag==false, call through to define_instance_class

 // which will throw LinkageError: duplicate class definition.

 // False is the requested default.

 // For better performance, the class loaders should synchronize

 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they

 // potentially waste time reading and parsing the bytestream.

 // Note: VM callers should ensure consistency of k/class_name,class_loader

 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {

   instanceKlassHandle nh = instanceKlassHandle(); // null Handle

   Symbol*  name_h = k->name(); // passed in class_name may be null

   ClassLoaderData* loader_data = class_loader_data(class_loader);

   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);

   int d_index = dictionary()->hash_to_index(d_hash);

 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS

   unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);

   int p_index = placeholders()->hash_to_index(p_hash);

   PlaceholderEntry* probe;

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // First check if class already defined

     if (UnsyncloadClass || (is_parallelDefine(class_loader))) {

       Klass* check = find_class(d_index, d_hash, name_h, loader_data);

       if (check != NULL) {

         return(instanceKlassHandle(THREAD, check));

       }

     }

     // Acquire define token for this class/classloader

     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);

     // Wait if another thread defining in parallel

     // All threads wait - even those that will throw duplicate class: otherwise

     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails

     // if other thread has not finished updating dictionary

     while (probe->definer() != NULL) {

       SystemDictionary_lock->wait();

     }

     // Only special cases allow parallel defines and can use other thread's results

     // Other cases fall through, and may run into duplicate defines

     // caught by finding an entry in the SystemDictionary

     if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {

         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);

         SystemDictionary_lock->notify_all();

 #ifdef ASSERT

         Klass* check = find_class(d_index, d_hash, name_h, loader_data);

         assert(check != NULL, "definer missed recording success");

 #endif

         return(instanceKlassHandle(THREAD, probe->instance_klass()));

     } else {

       // This thread will define the class (even if earlier thread tried and had an error)

       probe->set_definer(THREAD);

     }

   }

   define_instance_class(k, THREAD);

   Handle linkage_exception = Handle(); // null handle

   // definer must notify any waiting threads

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);

     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");

     if (probe != NULL) {

       if (HAS_PENDING_EXCEPTION) {

         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);

         CLEAR_PENDING_EXCEPTION;

       } else {

         probe->set_instance_klass(k());

       }

       probe->set_definer(NULL);

       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);

       SystemDictionary_lock->notify_all();

     }

   }

   // Can't throw exception while holding lock due to rank ordering

   if (linkage_exception() != NULL) {

     THROW_OOP_(linkage_exception(), nh); // throws exception and returns

   }

   return k;

 }

 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {

   // If class_loader is NULL we synchronize on _system_loader_lock_obj

   if (class_loader.is_null()) {

     return Handle(THREAD, _system_loader_lock_obj);

   } else {

     return class_loader;

   }

 }

 // This method is added to check how often we have to wait to grab loader

 // lock. The results are being recorded in the performance counters defined in

 // ClassLoader::_sync_systemLoaderLockContentionRate and

 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.

 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {

   if (!UsePerfData) {

     return;

   }

   assert(!loader_lock.is_null(), "NULL lock object");

   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)

       == ObjectSynchronizer::owner_other) {

     // contention will likely happen, so increment the corresponding

     // contention counter.

     if (loader_lock() == _system_loader_lock_obj) {

       ClassLoader::sync_systemLoaderLockContentionRate()->inc();

     } else {

       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();

     }

   }

 }

 // ----------------------------------------------------------------------------

 // Lookup

 Klass* SystemDictionary::find_class(int index, unsigned int hash,

                                       Symbol* class_name,

                                       ClassLoaderData* loader_data) {

   assert_locked_or_safepoint(SystemDictionary_lock);

   assert (index == dictionary()->index_for(class_name, loader_data),

           "incorrect index?");

   Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);

   return k;

 }

 // Basic find on classes in the midst of being loaded

 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,

                                            ClassLoaderData* loader_data) {

   assert_locked_or_safepoint(SystemDictionary_lock);

   unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);

   int p_index = placeholders()->hash_to_index(p_hash);

   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);

 }

 // Used for assertions and verification only

 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {

   #ifndef ASSERT

   guarantee(VerifyBeforeGC      ||

             VerifyDuringGC      ||

             VerifyBeforeExit    ||

             VerifyDuringStartup ||

             VerifyAfterGC, "too expensive");

   #endif

   assert_locked_or_safepoint(SystemDictionary_lock);

   // First look in the loaded class array

   unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);

   int d_index = dictionary()->hash_to_index(d_hash);

   return find_class(d_index, d_hash, class_name, loader_data);

 }

 // Get the next class in the diictionary.

 Klass* SystemDictionary::try_get_next_class() {

   return dictionary()->try_get_next_class();

 }

 // ----------------------------------------------------------------------------

 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock

 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in

 // before a new class is used.

 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {

   assert(k.not_null(), "just checking");

   assert_locked_or_safepoint(Compile_lock);

   // Link into hierachy. Make sure the vtables are initialized before linking into

   k->append_to_sibling_list();                    // add to superklass/sibling list

   k->process_interfaces(THREAD);                  // handle all "implements" declarations

   k->set_init_state(InstanceKlass::loaded);

   // Now flush all code that depended on old class hierarchy.

   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)

   // Also, first reinitialize vtable because it may have gotten out of synch

   // while the new class wasn't connected to the class hierarchy.

   Universe::flush_dependents_on(k);

 }

 // ----------------------------------------------------------------------------

 // GC support

 // Following roots during mark-sweep is separated in two phases.

 //

 // The first phase follows preloaded classes and all other system

 // classes, since these will never get unloaded anyway.

 //

 // The second phase removes (unloads) unreachable classes from the

 // system dictionary and follows the remaining classes' contents.

 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {

   roots_oops_do(blk, NULL);

 }

 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {

   // Follow all system classes and temporary placeholders in dictionary

   dictionary()->always_strong_classes_do(closure);

   // Placeholders. These represent classes we're actively loading.

   placeholders()->classes_do(closure);

 }

 // Calculate a "good" systemdictionary size based

 // on predicted or current loaded classes count

 int SystemDictionary::calculate_systemdictionary_size(int classcount) {

   int newsize = _old_default_sdsize;

   if ((classcount > 0)  && !DumpSharedSpaces) {

     int desiredsize = classcount/_average_depth_goal;

     for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;

          newsize = _primelist[++_sdgeneration]) {

       if (desiredsize <=  newsize) {

         break;

       }

     }

   }

   return newsize;

 }

 #ifdef ASSERT

 class VerifySDReachableAndLiveClosure : public OopClosure {

 private:

   BoolObjectClosure* _is_alive;

   template <class T> void do_oop_work(T* p) {

     oop obj = oopDesc::load_decode_heap_oop(p);

     guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");

   }

 public:

   VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }

   virtual void do_oop(oop* p)       { do_oop_work(p); }

   virtual void do_oop(narrowOop* p) { do_oop_work(p); }

 };

 #endif

 // Assumes classes in the SystemDictionary are only unloaded at a safepoint

 // Note: anonymous classes are not in the SD.

 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive, bool clean_alive) {

   // First, mark for unload all ClassLoaderData referencing a dead class loader.

   bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive, clean_alive);

   if (unloading_occurred) {

     JFR_ONLY(Jfr::on_unloading_classes();)

     dictionary()->do_unloading();

     constraints()->purge_loader_constraints();

     resolution_errors()->purge_resolution_errors();

   }

   // Oops referenced by the system dictionary may get unreachable independently

   // of the class loader (eg. cached protection domain oops). So we need to

   // explicitly unlink them here instead of in Dictionary::do_unloading.

   dictionary()->unlink(is_alive);

 #ifdef ASSERT

   VerifySDReachableAndLiveClosure cl(is_alive);

   dictionary()->oops_do(&cl);

 #endif

   return unloading_occurred;

 }

 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {

   strong->do_oop(&_java_system_loader);

   strong->do_oop(&_system_loader_lock_obj);

   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)

   // Adjust dictionary

   dictionary()->roots_oops_do(strong, weak);

   // Visit extra methods

   invoke_method_table()->oops_do(strong);

 }

 void SystemDictionary::oops_do(OopClosure* f) {

   f->do_oop(&_java_system_loader);

   f->do_oop(&_system_loader_lock_obj);

   CDS_ONLY(SystemDictionaryShared::oops_do(f);)

   // Adjust dictionary

   dictionary()->oops_do(f);

   // Visit extra methods

   invoke_method_table()->oops_do(f);

 }

 // Extended Class redefinition support.

 // If one of these classes is replaced, we need to replace it in these places.

 // KlassClosure::do_klass should take the address of a class but we can

 // change that later.

 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {

   for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {

     f->do_klass(_well_known_klasses[k]);

   }

   {

     for (int i = 0; i < T_VOID+1; i++) {

       if (_box_klasses[i] != NULL) {

         assert(i >= T_BOOLEAN, "checking");

         f->do_klass(_box_klasses[i]);

       }

     }

   }

   FilteredFieldsMap::classes_do(f);

 }

 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {

   f->do_klass(_abstract_ownable_synchronizer_klass);

 }

 // Just the classes from defining class loaders

 // Don't iterate over placeholders

 void SystemDictionary::classes_do(void f(Klass*)) {

   dictionary()->classes_do(f);

 }

 // Added for initialize_itable_for_klass

 //   Just the classes from defining class loaders

 // Don't iterate over placeholders

 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {

   dictionary()->classes_do(f, CHECK);

 }

 //   All classes, and their class loaders

 // Don't iterate over placeholders

 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {

   dictionary()->classes_do(f);

 }

 void SystemDictionary::placeholders_do(void f(Symbol*)) {

   placeholders()->entries_do(f);

 }

 void SystemDictionary::methods_do(void f(Method*)) {

   dictionary()->methods_do(f);

   invoke_method_table()->methods_do(f);

 }

 void SystemDictionary::remove_classes_in_error_state() {

   dictionary()->remove_classes_in_error_state();

 }

 // ----------------------------------------------------------------------------

 // Lazily load klasses

 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {

   assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");

   // if multiple threads calling this function, only one thread will load

   // the class.  The other threads will find the loaded version once the

   // class is loaded.

   Klass* aos = _abstract_ownable_synchronizer_klass;

   if (aos == NULL) {

     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);

     // Force a fence to prevent any read before the write completes

     OrderAccess::fence();

     _abstract_ownable_synchronizer_klass = k;

   }

 }

 // ----------------------------------------------------------------------------

 // Initialization

 void SystemDictionary::initialize(TRAPS) {

   // Allocate arrays

   assert(dictionary() == NULL,

          "SystemDictionary should only be initialized once");

   _sdgeneration        = 0;

   _dictionary          = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));

   _placeholders        = new PlaceholderTable(_nof_buckets);

   _number_of_modifications = 0;

   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);

   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);

   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);

   // Allocate private object used as system class loader lock

   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);

   // Initialize basic classes

   initialize_preloaded_classes(CHECK);

 }

 // Compact table of directions on the initialization of klasses:

 static const short wk_init_info[] = {

   #define WK_KLASS_INIT_INFO(name, symbol, option) \

     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \

           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \

       | (int)SystemDictionary::option ),

   WK_KLASSES_DO(WK_KLASS_INIT_INFO)

   #undef WK_KLASS_INIT_INFO

   0

 };

 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {

   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");

   int  info = wk_init_info[id - FIRST_WKID];

   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);

   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);

   Klass**    klassp = &_well_known_klasses[id];

   bool must_load = (init_opt < SystemDictionary::Opt);

   if ((*klassp) == NULL) {

     if (must_load) {

       (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class

     } else {

       (*klassp) = resolve_or_null(symbol,       CHECK_0); // load optional klass

     }

   }

   return ((*klassp) != NULL);

 }

 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {

   assert((int)start_id <= (int)limit_id, "IDs are out of order!");

   for (int id = (int)start_id; id < (int)limit_id; id++) {

     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");

     int info = wk_init_info[id - FIRST_WKID];

     int sid  = (info >> CEIL_LG_OPTION_LIMIT);

     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));

     initialize_wk_klass((WKID)id, opt, CHECK);

   }

   // move the starting value forward to the limit:

   start_id = limit_id;

 }

 void SystemDictionary::initialize_preloaded_classes(TRAPS) {

   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");

   // Preload commonly used klasses

   WKID scan = FIRST_WKID;

   // first do Object, then String, Class

   if (UseSharedSpaces) {

     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);

     // Initialize the constant pool for the Object_class

     InstanceKlass* ik = InstanceKlass::cast(Object_klass());

     ik->constants()->restore_unshareable_info(CHECK);

     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);

   } else {

     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);

   }

   // Calculate offsets for String and Class classes since they are loaded and

   // can be used after this point.

   java_lang_String::compute_offsets();

   java_lang_Class::compute_offsets();

   // Fixup mirrors for classes loaded before java.lang.Class.

   // These calls iterate over the objects currently in the perm gen

   // so calling them at this point is matters (not before when there

   // are fewer objects and not later after there are more objects

   // in the perm gen.

   Universe::initialize_basic_type_mirrors(CHECK);

   Universe::fixup_mirrors(CHECK);

   // do a bunch more:

   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);

   // Preload ref klasses and set reference types

   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);

   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));

   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);

   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);

   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);

   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);

   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);

   InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);

   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(ReferenceQueue_klass), scan, CHECK);

   // JSR 292 classes

   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);

   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);

   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);

   if (EnableInvokeDynamic) {

     initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);

   } else {

     // Skip the JSR 292 classes, if not enabled.

     scan = WKID(jsr292_group_end + 1);

   }

   initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);

   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);

   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);

   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);

   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);

   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);

   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);

   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);

   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);

   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);

   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);

   { // Compute whether we should use loadClass or loadClassInternal when loading classes.

     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());

     _has_loadClassInternal = (method != NULL);

   }

   { // Compute whether we should use checkPackageAccess or NOT

     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());

     _has_checkPackageAccess = (method != NULL);

   }

 }

 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).

 // If so, returns the basic type it holds.  If not, returns T_OBJECT.

 BasicType SystemDictionary::box_klass_type(Klass* k) {

   assert(k != NULL, "");

   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {

     if (_box_klasses[i] == k)

       return (BasicType)i;

   }

   return T_OBJECT;

 }

 // Constraints on class loaders. The details of the algorithm can be

 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java

 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is

 // that the system dictionary needs to maintain a set of contraints that

 // must be satisfied by all classes in the dictionary.

 // if defining is true, then LinkageError if already in systemDictionary

 // if initiating loader, then ok if InstanceKlass matches existing entry

 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,

                                          instanceKlassHandle k,

                                          Handle class_loader, bool defining,

                                          TRAPS) {

   const char *linkage_error = NULL;

   {

     Symbol*  name  = k->name();

     ClassLoaderData *loader_data = class_loader_data(class_loader);

     MutexLocker mu(SystemDictionary_lock, THREAD);

     Klass* check = find_class(d_index, d_hash, name, loader_data);

     if (check != (Klass*)NULL) {

       // if different InstanceKlass - duplicate class definition,

       // else - ok, class loaded by a different thread in parallel,

       // we should only have found it if it was done loading and ok to use

       // system dictionary only holds instance classes, placeholders

       // also holds array classes

       assert(check->oop_is_instance(), "noninstance in systemdictionary");

       if ((defining == true) || (k() != check)) {

         linkage_error = "loader (instance of  %s): attempted  duplicate class "

           "definition for name: \"%s\"";

       } else {

         return;

       }

     }

 #ifdef ASSERT

     Symbol* ph_check = find_placeholder(name, loader_data);

     assert(ph_check == NULL || ph_check == name, "invalid symbol");

 #endif

     if (linkage_error == NULL) {

       if (constraints()->check_or_update(k, class_loader, name) == false) {

         linkage_error = "loader constraint violation: loader (instance of %s)"

           " previously initiated loading for a different type with name \"%s\"";

       }

     }

   }

   // Throw error now if needed (cannot throw while holding

   // SystemDictionary_lock because of rank ordering)

   if (linkage_error) {

     ResourceMark rm(THREAD);

     const char* class_loader_name = loader_name(class_loader());

     char* type_name = k->name()->as_C_string();

     size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +

       strlen(type_name);

     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);

     jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);

     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);

   }

 }

 // Update system dictionary - done after check_constraint and add_to_hierachy

 // have been called.

 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,

                                          int p_index, unsigned int p_hash,

                                          instanceKlassHandle k,

                                          Handle class_loader,

                                          TRAPS) {

   // Compile_lock prevents systemDictionary updates during compilations

   assert_locked_or_safepoint(Compile_lock);

   Symbol*  name  = k->name();

   ClassLoaderData *loader_data = class_loader_data(class_loader);

   {

   MutexLocker mu1(SystemDictionary_lock, THREAD);

   // See whether biased locking is enabled and if so set it for this

   // klass.

   // Note that this must be done past the last potential blocking

   // point / safepoint. We enable biased locking lazily using a

   // VM_Operation to iterate the SystemDictionary and installing the

   // biasable mark word into each InstanceKlass's prototype header.

   // To avoid race conditions where we accidentally miss enabling the

   // optimization for one class in the process of being added to the

   // dictionary, we must not safepoint after the test of

   // BiasedLocking::enabled().

   if (UseBiasedLocking && BiasedLocking::enabled()) {

     // Set biased locking bit for all loaded classes; it will be

     // cleared if revocation occurs too often for this type

     // NOTE that we must only do this when the class is initally

     // defined, not each time it is referenced from a new class loader

     if (k->class_loader() == class_loader()) {

       k->set_prototype_header(markOopDesc::biased_locking_prototype());

     }

   }

   // Make a new system dictionary entry.

   Klass* sd_check = find_class(d_index, d_hash, name, loader_data);

   if (sd_check == NULL) {

     dictionary()->add_klass(name, loader_data, k);

     notice_modification();

   }

 #ifdef ASSERT

   sd_check = find_class(d_index, d_hash, name, loader_data);

   assert (sd_check != NULL, "should have entry in system dictionary");

   // Note: there may be a placeholder entry: for circularity testing

   // or for parallel defines

 #endif

     SystemDictionary_lock->notify_all();

   }

 }

 // Try to find a class name using the loader constraints.  The

 // loader constraints might know about a class that isn't fully loaded

 // yet and these will be ignored.

 Klass* SystemDictionary::find_constrained_instance_or_array_klass(

                     Symbol* class_name, Handle class_loader, TRAPS) {

   // First see if it has been loaded directly.

   // Force the protection domain to be null.  (This removes protection checks.)

   Handle no_protection_domain;

   Klass* klass = find_instance_or_array_klass(class_name, class_loader,

                                               no_protection_domain, CHECK_NULL);

   if (klass != NULL)

     return klass;

   // Now look to see if it has been loaded elsewhere, and is subject to

   // a loader constraint that would require this loader to return the

   // klass that is already loaded.

   if (FieldType::is_array(class_name)) {

     // For array classes, their Klass*s are not kept in the

     // constraint table. The element Klass*s are.

     FieldArrayInfo fd;

     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));

     if (t != T_OBJECT) {

       klass = Universe::typeArrayKlassObj(t);

     } else {

       MutexLocker mu(SystemDictionary_lock, THREAD);

       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);

     }

     // If element class already loaded, allocate array klass

     if (klass != NULL) {

       klass = klass->array_klass_or_null(fd.dimension());

     }

   } else {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // Non-array classes are easy: simply check the constraint table.

     klass = constraints()->find_constrained_klass(class_name, class_loader);

   }

   return klass;

 }

 bool SystemDictionary::add_loader_constraint(Symbol* class_name,

                                              Handle class_loader1,

                                              Handle class_loader2,

                                              Thread* THREAD) {

   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);

   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);

   Symbol* constraint_name = NULL;

   if (!FieldType::is_array(class_name)) {

     constraint_name = class_name;

   } else {

     // For array classes, their Klass*s are not kept in the

     // constraint table. The element classes are.

     FieldArrayInfo fd;

     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));

     // primitive types always pass

     if (t != T_OBJECT) {

       return true;

     } else {

       constraint_name = fd.object_key();

     }

   }

   unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);

   int d_index1 = dictionary()->hash_to_index(d_hash1);

   unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);

   int d_index2 = dictionary()->hash_to_index(d_hash2);

   {

   MutexLocker mu_s(SystemDictionary_lock, THREAD);

   // Better never do a GC while we're holding these oops

   No_Safepoint_Verifier nosafepoint;

   Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);

   Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);

   return constraints()->add_entry(constraint_name, klass1, class_loader1,

                                   klass2, class_loader2);

   }

 }

 // Add entry to resolution error table to record the error when the first

 // attempt to resolve a reference to a class has failed.

 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {

   unsigned int hash = resolution_errors()->compute_hash(pool, which);

   int index = resolution_errors()->hash_to_index(hash);

   {

     MutexLocker ml(SystemDictionary_lock, Thread::current());

     resolution_errors()->add_entry(index, hash, pool, which, error);

   }

 }

 // Delete a resolution error for RedefineClasses for a constant pool is going away

 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {

   resolution_errors()->delete_entry(pool);

 }

 // Lookup resolution error table. Returns error if found, otherwise NULL.

 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {

   unsigned int hash = resolution_errors()->compute_hash(pool, which);

   int index = resolution_errors()->hash_to_index(hash);

   {

     MutexLocker ml(SystemDictionary_lock, Thread::current());

     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);

     return (entry != NULL) ? entry->error() : (Symbol*)NULL;

   }

 }

 // Signature constraints ensure that callers and callees agree about

 // the meaning of type names in their signatures.  This routine is the

 // intake for constraints.  It collects them from several places:

 //

 //  * LinkResolver::resolve_method (if check_access is true) requires

 //    that the resolving class (the caller) and the defining class of

 //    the resolved method (the callee) agree on each type in the

 //    method's signature.

 //

 //  * LinkResolver::resolve_interface_method performs exactly the same

 //    checks.

 //

 //  * LinkResolver::resolve_field requires that the constant pool

 //    attempting to link to a field agree with the field's defining

 //    class about the type of the field signature.

 //

 //  * klassVtable::initialize_vtable requires that, when a class

 //    overrides a vtable entry allocated by a superclass, that the

 //    overriding method (i.e., the callee) agree with the superclass

 //    on each type in the method's signature.

 //

 //  * klassItable::initialize_itable requires that, when a class fills

 //    in its itables, for each non-abstract method installed in an

 //    itable, the method (i.e., the callee) agree with the interface

 //    on each type in the method's signature.

 //

 // All those methods have a boolean (check_access, checkconstraints)

 // which turns off the checks.  This is used from specialized contexts

 // such as bootstrapping, dumping, and debugging.

 //

 // No direct constraint is placed between the class and its

 // supertypes.  Constraints are only placed along linked relations

 // between callers and callees.  When a method overrides or implements

 // an abstract method in a supertype (superclass or interface), the

 // constraints are placed as if the supertype were the caller to the

 // overriding method.  (This works well, since callers to the

 // supertype have already established agreement between themselves and

 // the supertype.)  As a result of all this, a class can disagree with

 // its supertype about the meaning of a type name, as long as that

 // class neither calls a relevant method of the supertype, nor is

 // called (perhaps via an override) from the supertype.

 //

 //

 // SystemDictionary::check_signature_loaders(sig, l1, l2)

 //

 // Make sure all class components (including arrays) in the given

 // signature will be resolved to the same class in both loaders.

 // Returns the name of the type that failed a loader constraint check, or

 // NULL if no constraint failed.  No exception except OOME is thrown.

 // Arrays are not added to the loader constraint table, their elements are.

 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,

                                                Handle loader1, Handle loader2,

                                                bool is_method, TRAPS)  {

   // Nothing to do if loaders are the same.

   if (loader1() == loader2()) {

     return NULL;

   }

   SignatureStream sig_strm(signature, is_method);

   while (!sig_strm.is_done()) {

     if (sig_strm.is_object()) {

       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);

       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {

         return sig;

       }

     }

     sig_strm.next();

   }

   return NULL;

 }

 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,

                                                             Symbol* signature,

                                                             TRAPS) {

   methodHandle empty;

   assert(EnableInvokeDynamic, "");

   assert(MethodHandles::is_signature_polymorphic(iid) &&

          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&

          iid != vmIntrinsics::_invokeGeneric,

          err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));

   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);

   int          index = invoke_method_table()->hash_to_index(hash);

   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);

   methodHandle m;

   if (spe == NULL || spe->method() == NULL) {

     spe = NULL;

     // Must create lots of stuff here, but outside of the SystemDictionary lock.

     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));

     if (!Arguments::is_interpreter_only()) {

       // Generate a compiled form of the MH intrinsic.

       AdapterHandlerLibrary::create_native_wrapper(m);

       // Check if have the compiled code.

       if (!m->has_compiled_code()) {

         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),

                    "out of space in CodeCache for method handle intrinsic", empty);

       }

     }

     // Now grab the lock.  We might have to throw away the new method,

     // if a racing thread has managed to install one at the same time.

     {

       MutexLocker ml(SystemDictionary_lock, THREAD);

       spe = invoke_method_table()->find_entry(index, hash, signature, iid);

       if (spe == NULL)

         spe = invoke_method_table()->add_entry(index, hash, signature, iid);

       if (spe->method() == NULL)

         spe->set_method(m());

     }

   }

   assert(spe != NULL && spe->method() != NULL, "");

   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&

          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),

          "MH intrinsic invariant");

   return spe->method();

 }

 // Helper for unpacking the return value from linkMethod and linkCallSite.

 static methodHandle unpack_method_and_appendix(Handle mname,

                                                KlassHandle accessing_klass,

                                                objArrayHandle appendix_box,

                                                Handle* appendix_result,

                                                TRAPS) {

   methodHandle empty;

   if (mname.not_null()) {

     Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());

     if (vmtarget != NULL && vmtarget->is_method()) {

       Method* m = (Method*)vmtarget;

       oop appendix = appendix_box->obj_at(0);

       if (TraceMethodHandles) {

     #ifndef PRODUCT

         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));

         m->print();

         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }

         tty->cr();

     #endif //PRODUCT

       }

       (*appendix_result) = Handle(THREAD, appendix);

       // the target is stored in the cpCache and if a reference to this

       // MethodName is dropped we need a way to make sure the

       // class_loader containing this method is kept alive.

       // FIXME: the appendix might also preserve this dependency.

       ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();

       this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM

       return methodHandle(THREAD, m);

     }

   }

   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);

   return empty;

 }

 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,

                                                           Symbol* signature,

                                                           KlassHandle accessing_klass,

                                                           Handle *appendix_result,

                                                           Handle *method_type_result,

                                                           TRAPS) {

   methodHandle empty;

   assert(EnableInvokeDynamic, "");

   assert(!THREAD->is_Compiler_thread(), "");

   Handle method_type =

     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));

   KlassHandle  mh_klass = SystemDictionary::MethodHandle_klass();

   int ref_kind = JVM_REF_invokeVirtual;

   Handle name_str = StringTable::intern(name, CHECK_(empty));

   objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));

   assert(appendix_box->obj_at(0) == NULL, "");

   // This should not happen.  JDK code should take care of that.

   if (accessing_klass.is_null() || method_type.is_null()) {

     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);

   }

   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName

   JavaCallArguments args;

   args.push_oop(accessing_klass()->java_mirror());

   args.push_int(ref_kind);

   args.push_oop(mh_klass()->java_mirror());

   args.push_oop(name_str());

   args.push_oop(method_type());

   args.push_oop(appendix_box());

   JavaValue result(T_OBJECT);

   JavaCalls::call_static(&result,

                          SystemDictionary::MethodHandleNatives_klass(),

                          vmSymbols::linkMethod_name(),

                          vmSymbols::linkMethod_signature(),

                          &args, CHECK_(empty));

   Handle mname(THREAD, (oop) result.get_jobject());

   (*method_type_result) = method_type;

   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);

 }

 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.

 // We must ensure that all class loaders everywhere will reach this class, for any client.

 // This is a safe bet for public classes in java.lang, such as Object and String.

 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.

 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.

 static bool is_always_visible_class(oop mirror) {

   Klass* klass = java_lang_Class::as_Klass(mirror);

   if (klass->oop_is_objArray()) {

     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type

   }

   if (klass->oop_is_typeArray()) {

     return true; // primitive array

   }

   assert(klass->oop_is_instance(), klass->external_name());

   return klass->is_public() &&

          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang

           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke

 }

 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given

 // signature, as interpreted relative to the given class loader.

 // Because of class loader constraints, all method handle usage must be

 // consistent with this loader.

 Handle SystemDictionary::find_method_handle_type(Symbol* signature,

                                                  KlassHandle accessing_klass,

                                                  TRAPS) {

   Handle empty;

   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics

   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);

   int          index = invoke_method_table()->hash_to_index(hash);

   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);

   if (spe != NULL && spe->method_type() != NULL) {

     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");

     return Handle(THREAD, spe->method_type());

   } else if (THREAD->is_Compiler_thread()) {

     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME

     return Handle();  // do not attempt from within compiler, unless it was cached

   }

   Handle class_loader, protection_domain;

   if (accessing_klass.not_null()) {

     class_loader      = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());

     protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());

   }

   bool can_be_cached = true;

   int npts = ArgumentCount(signature).size();

   objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));

   int arg = 0;

   Handle rt; // the return type from the signature

   ResourceMark rm(THREAD);

   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {

     oop mirror = NULL;

     if (can_be_cached) {

       // Use neutral class loader to lookup candidate classes to be placed in the cache.

       mirror = ss.as_java_mirror(Handle(), Handle(),

                                  SignatureStream::ReturnNull, CHECK_(empty));

       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {

         // Fall back to accessing_klass context.

         can_be_cached = false;

       }

     }

     if (!can_be_cached) {

       // Resolve, throwing a real error if it doesn't work.

       mirror = ss.as_java_mirror(class_loader, protection_domain,

                                  SignatureStream::NCDFError, CHECK_(empty));

     }

     assert(!oopDesc::is_null(mirror), ss.as_symbol(THREAD)->as_C_string());

     if (ss.at_return_type())

       rt = Handle(THREAD, mirror);

     else

       pts->obj_at_put(arg++, mirror);

     // Check accessibility.

     if (ss.is_object() && accessing_klass.not_null()) {

       Klass* sel_klass = java_lang_Class::as_Klass(mirror);

       mirror = NULL;  // safety

       // Emulate ConstantPool::verify_constant_pool_resolve.

       if (sel_klass->oop_is_objArray())

         sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();

       if (sel_klass->oop_is_instance()) {

         KlassHandle sel_kh(THREAD, sel_klass);

         LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));

       }

     }

   }

   assert(arg == npts, "");

   // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType

   JavaCallArguments args(Handle(THREAD, rt()));

   args.push_oop(pts());

   JavaValue result(T_OBJECT);

   JavaCalls::call_static(&result,

                          SystemDictionary::MethodHandleNatives_klass(),

                          vmSymbols::findMethodHandleType_name(),

                          vmSymbols::findMethodHandleType_signature(),

                          &args, CHECK_(empty));

   Handle method_type(THREAD, (oop) result.get_jobject());

   if (can_be_cached) {

     // We can cache this MethodType inside the JVM.

     MutexLocker ml(SystemDictionary_lock, THREAD);

     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);

     if (spe == NULL)

       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);

     if (spe->method_type() == NULL) {

       spe->set_method_type(method_type());

     }

   }

   // report back to the caller with the MethodType

   return method_type;

 }

 // Ask Java code to find or construct a method handle constant.

 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,

                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual

                                                      KlassHandle callee,

                                                      Symbol* name_sym,

                                                      Symbol* signature,

                                                      TRAPS) {

   Handle empty;

   Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));

   Handle type;

   if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {

     type = find_method_handle_type(signature, caller, CHECK_(empty));

   } else if (caller.is_null()) {

     // This should not happen.  JDK code should take care of that.

     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);

   } else {

     ResourceMark rm(THREAD);

     SignatureStream ss(signature, false);

     if (!ss.is_done()) {

       oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),

                                      SignatureStream::NCDFError, CHECK_(empty));

       type = Handle(THREAD, mirror);

       ss.next();

       if (!ss.is_done())  type = Handle();  // error!

     }

   }

   if (type.is_null()) {

     THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);

   }

   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle

   JavaCallArguments args;

   args.push_oop(caller->java_mirror());  // the referring class

   args.push_int(ref_kind);

   args.push_oop(callee->java_mirror());  // the target class

   args.push_oop(name());

   args.push_oop(type());

   JavaValue result(T_OBJECT);

   JavaCalls::call_static(&result,

                          SystemDictionary::MethodHandleNatives_klass(),

                          vmSymbols::linkMethodHandleConstant_name(),

                          vmSymbols::linkMethodHandleConstant_signature(),

                          &args, CHECK_(empty));

   return Handle(THREAD, (oop) result.get_jobject());

 }

 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given

 // name and signature, as interpreted relative to the given class loader.

 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,

                                                               Handle bootstrap_specifier,

                                                               Symbol* name,

                                                               Symbol* type,

                                                               Handle *appendix_result,

                                                               Handle *method_type_result,

                                                               TRAPS) {

   methodHandle empty;

   Handle bsm, info;

   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {

     bsm = bootstrap_specifier;

   } else {

     assert(bootstrap_specifier->is_objArray(), "");

     objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());

     int len = args->length();

     assert(len >= 1, "");

     bsm = Handle(THREAD, args->obj_at(0));

     if (len > 1) {

       objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));

       for (int i = 1; i < len; i++)

         args1->obj_at_put(i-1, args->obj_at(i));

       info = Handle(THREAD, args1);

     }

   }

   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),

             "caller must supply a valid BSM");

   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));

   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));

   // This should not happen.  JDK code should take care of that.

   if (caller.is_null() || method_type.is_null()) {

     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);

   }

   objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));

   assert(appendix_box->obj_at(0) == NULL, "");

   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)

   JavaCallArguments args;