jdk8-mips64-public/hotspot: src/share/vm/classfile/systemDictionary.cpp@aefb345d3f5e (annotated)

src/share/vm/classfile/systemDictionary.cpp@aefb345d3f5e (annotated)

src/share/vm/classfile/systemDictionary.cpp

Thu, 10 Jan 2013 17:38:20 -0500

author: acorn
date: Thu, 10 Jan 2013 17:38:20 -0500
changeset 4425: aefb345d3f5e
parent 4304: 90273fc0a981
child 4492: 8b46b0196eb0
permissions: -rw-r--r--

7199207: NPG: Crash in PlaceholderTable::verify after StackOverflow
Summary: Reduce scope of placeholder table entries to improve cleanup
Reviewed-by: dholmes, coleenp

 /*
  * Copyright (c) 1997, 2013, 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"
 #include "classfile/vmSymbols.hpp"
 #include "compiler/compileBroker.hpp"
 #include "interpreter/bytecodeStream.hpp"
 #include "interpreter/interpreter.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/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/signature.hpp"
 #include "services/classLoadingService.hpp"
 #include "services/threadService.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,
 ,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();
 }
 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, CHECK_NULL);
 }
 // ----------------------------------------------------------------------------
 // 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
 // ----------------------------------------------------------------------------
 // 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;
 }
 // ----------------------------------------------------------------------------
 // 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);
 }
 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");
   // 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 and doesn't use the CHECK macro.
         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;
   }
 #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 = register_loader(class_loader, CHECK_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;
   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");
     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, "");
     k->set_host_klass(host_klass());
     // 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.
     }
     // 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());
     }
   }
   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.
   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
                                                              loader_data,
                                                              protection_domain,
                                                              parsed_name,
                                                              verify,
                                                              THREAD);
   const char* pkg = "java/";
   if (!HAS_PENDING_EXCEPTION &&
       !class_loader.is_null() &&
       parsed_name != NULL &&
       !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
     // 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, '/');
     *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");
     // 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();
 }
 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));
   return load_shared_class(ik, class_loader, THREAD);
 }
 // Note well!  Changes to this method may affect oop access order
 // in the shared archive.  Please take care to not make changes that
 // adversely affect cold start time by changing the oop access order
 // that is specified in dump.cpp MarkAndMoveOrderedReadOnly and
 // MarkAndMoveOrderedReadWrite closures.
 instanceKlassHandle SystemDictionary::load_shared_class(
                  instanceKlassHandle ik, Handle class_loader, TRAPS) {
   assert(class_loader.is_null(), "non-null classloader for shared class?");
   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();
       resolve_super_or_fail(class_name, cn,
                             class_loader, Handle(), true, CHECK_(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();
       resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(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 the bootstrap
     // classloader, so this will never cause a deadlock on
     // a custom class loader lock.
     {
       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
       check_loader_lock_contention(lockObject, THREAD);
       ObjectLocker ol(lockObject, THREAD, true);
       ik->restore_unshareable_info(CHECK_(nh));
     }
     if (TraceClassLoading) {
       ResourceMark rm;
       tty->print("[Loaded %s", ik->external_name());
       tty->print(" from shared objects file");
       tty->print_cr("]");
     }
     // notify a class loaded from shared object
     ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
                                              true /* shared class */);
   }
   return ik;
 }
 #ifdef KERNEL
 // Some classes on the bootstrap class path haven't been installed on the
 // system yet.  Call the DownloadManager method to make them appear in the
 // bootstrap class path and try again to load the named class.
 // Note that with delegation class loaders all classes in another loader will
 // first try to call this so it'd better be fast!!
 static instanceKlassHandle download_and_retry_class_load(
                                                     Symbol* class_name,
                                                     TRAPS) {
   Klass* dlm = SystemDictionary::DownloadManager_klass();
   instanceKlassHandle nk;
   // If download manager class isn't loaded just return.
   if (dlm == NULL) return nk;
   { HandleMark hm(THREAD);
     ResourceMark rm(THREAD);
     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nk));
     Handle class_string = java_lang_String::externalize_classname(s, CHECK_(nk));
     // return value
     JavaValue result(T_OBJECT);
     // Call the DownloadManager.  We assume that it has a lock because
     // multiple classes could be not found and downloaded at the same time.
     // class sun.misc.DownloadManager;
     // public static String getBootClassPathEntryForClass(String className);
     JavaCalls::call_static(&result,
                        KlassHandle(THREAD, dlm),
                        vmSymbols::getBootClassPathEntryForClass_name(),
                        vmSymbols::string_string_signature(),
                        class_string,
                        CHECK_(nk));
     // Get result.string and add to bootclasspath
     assert(result.get_type() == T_OBJECT, "just checking");
     oop obj = (oop) result.get_jobject();
     if (obj == NULL) { return nk; }
     Handle h_obj(THREAD, obj);
     char* new_class_name = java_lang_String::as_platform_dependent_str(h_obj,
                                                                   CHECK_(nk));
     // lock the loader
     // we use this lock because JVMTI does.
     Handle loader_lock(THREAD, SystemDictionary::system_loader_lock());
     ObjectLocker ol(loader_lock, THREAD);
     // add the file to the bootclasspath
     ClassLoader::update_class_path_entry_list(new_class_name, true);
   } // end HandleMark
   if (TraceClassLoading) {
     ClassLoader::print_bootclasspath();
   }
   return ClassLoader::load_classfile(class_name, CHECK_(nk));
 }
 #endif // KERNEL
 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;
     {
       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
       k = load_shared_class(class_name, class_loader, THREAD);
     }
     if (k.is_null()) {
       // Use VM class loader
       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
       k = ClassLoader::load_classfile(class_name, CHECK_(nh));
     }
 #ifdef KERNEL
     // If the VM class loader has failed to load the class, call the
     // DownloadManager class to make it magically appear on the classpath
     // and try again.  This is only configured with the Kernel VM.
     if (k.is_null()) {
       k = download_and_retry_class_load(class_name, CHECK_(nh));
     }
 #endif // KERNEL
     // 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;
   }
 }
 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());
   }
 }
 // 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 ||
             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) {
   blk->do_oop(&_java_system_loader);
   blk->do_oop(&_system_loader_lock_obj);
   dictionary()->always_strong_oops_do(blk);
   // Visit extra methods
   invoke_method_table()->oops_do(blk);
 }
 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;
 }
 // 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) {
   // First, mark for unload all ClassLoaderData referencing a dead class loader.
   bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive);
   bool unloading_occurred = false;
   if (has_dead_loaders) {
     unloading_occurred = dictionary()->do_unloading();
     constraints()->purge_loader_constraints();
     resolution_errors()->purge_resolution_errors();
 }
   return unloading_occurred;
 }
 void SystemDictionary::oops_do(OopClosure* f) {
   f->do_oop(&_java_system_loader);
   f->do_oop(&_system_loader_lock_obj);
   // 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);
 }
 //   All classes, and their class loaders
 //   (added for helpers that use HandleMarks and ResourceMarks)
 // Don't iterate over placeholders
 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*, TRAPS), TRAPS) {
   dictionary()->classes_do(f, CHECK);
 }
 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);
 }
 // ----------------------------------------------------------------------------
 // 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
 
 };
 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);
   bool try_load  = true;
   if (init_opt == SystemDictionary::Opt_Kernel) {
 #ifndef KERNEL
     try_load = false;
 #endif //KERNEL
   }
   if ((*klassp) == NULL && try_load) {
     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(PhantomReference_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);
   // 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);
 #ifdef KERNEL
   if (DownloadManager_klass() == NULL) {
     warning("Cannot find sun/jkernel/DownloadManager");
   }
 #endif // KERNEL
   { // 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());
     }
   }
   // Assign a classid if one has not already been assigned.  The
   // counter does not need to be atomically incremented since this
   // is only done while holding the SystemDictionary_lock.
   // All loaded classes get a unique ID.
   TRACE_INIT_ID(k);
   // 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. The returned C string needs cleaning up
 // with a ResourceMark in the caller.  No exception except OOME is thrown.
 // Arrays are not added to the loader constraint table, their elements are.
 char* 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;
   }
   ResourceMark rm(THREAD);
   SignatureStream sig_strm(signature, is_method);
   while (!sig_strm.is_done()) {
     if (sig_strm.is_object()) {
       Symbol* s = sig_strm.as_symbol(CHECK_NULL);
       Symbol*  sig  = s;
       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
         return sig->as_C_string();
       }
     }
     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));
     CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier,
                                   methodHandle(), CompileThreshold, "MH", CHECK_(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, "");
   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": ", 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));
   if (false) {  // FIXME: Decide if the Java upcall should resolve signatures.
     method_type = java_lang_String::create_from_symbol(signature, 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, "");
   // 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);
 }
 // 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;
   bool is_on_bcp = true;  // keep this true as long as we can materialize from the boot classloader
   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 (is_on_bcp) {
       // Note:  class_loader & protection_domain are both null at this point.
       mirror = ss.as_java_mirror(class_loader, protection_domain,
                                  SignatureStream::ReturnNull, CHECK_(empty));
       if (mirror == NULL) {
         // fall back from BCP to accessing_klass
         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());
         }
         is_on_bcp = false;
       }
     }
     if (!is_on_bcp) {
       // Resolve, throwing a real error if it doesn't work.
       mirror = ss.as_java_mirror(class_loader, protection_domain,
                                  SignatureStream::NCDFError, CHECK_(empty));
     }
     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 (is_on_bcp) {
     // 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 {
     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));
   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;
   args.push_oop(caller->java_mirror());
   args.push_oop(bsm());
   args.push_oop(method_name());
   args.push_oop(method_type());
   args.push_oop(info());
   args.push_oop(appendix_box);
   JavaValue result(T_OBJECT);
   JavaCalls::call_static(&result,
                          SystemDictionary::MethodHandleNatives_klass(),
                          vmSymbols::linkCallSite_name(),
                          vmSymbols::linkCallSite_signature(),
                          &args, CHECK_(empty));
   Handle mname(THREAD, (oop) result.get_jobject());
   (*method_type_result) = method_type;
   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
 }
 // Since the identity hash code for symbols changes when the symbols are
 // moved from the regular perm gen (hash in the mark word) to the shared
 // spaces (hash is the address), the classes loaded into the dictionary
 // may be in the wrong buckets.
 void SystemDictionary::reorder_dictionary() {
   dictionary()->reorder_dictionary();
 }
 void SystemDictionary::copy_buckets(char** top, char* end) {
   dictionary()->copy_buckets(top, end);
 }
 void SystemDictionary::copy_table(char** top, char* end) {
   dictionary()->copy_table(top, end);
 }
 void SystemDictionary::reverse() {
   dictionary()->reverse();
 }
 int SystemDictionary::number_of_classes() {
   return dictionary()->number_of_entries();
 }
 // ----------------------------------------------------------------------------
 #ifndef PRODUCT
 void SystemDictionary::print() {
   dictionary()->print();
   // Placeholders
   GCMutexLocker mu(SystemDictionary_lock);
   placeholders()->print();
   // loader constraints - print under SD_lock
   constraints()->print();
 }
 #endif
 void SystemDictionary::verify() {
   guarantee(dictionary() != NULL, "Verify of system dictionary failed");
   guarantee(constraints() != NULL,
             "Verify of loader constraints failed");
   guarantee(dictionary()->number_of_entries() >= 0 &&
             placeholders()->number_of_entries() >= 0,
             "Verify of system dictionary failed");
   // Verify dictionary
   dictionary()->verify();
   GCMutexLocker mu(SystemDictionary_lock);
   placeholders()->verify();
   // Verify constraint table
   guarantee(constraints() != NULL, "Verify of loader constraints failed");
   constraints()->verify(dictionary(), placeholders());
 }
 void SystemDictionary::verify_obj_klass_present(Symbol* class_name,
                                                 ClassLoaderData* loader_data) {
   GCMutexLocker mu(SystemDictionary_lock);
   Symbol* name;
   Klass* probe = find_class(class_name, loader_data);
   if (probe == NULL) {
     probe = SystemDictionary::find_shared_class(class_name);
     if (probe == NULL) {
       name = find_placeholder(class_name, loader_data);
     }
   }
   guarantee(probe != NULL || name != NULL,
             "Loaded klasses should be in SystemDictionary");
 }
 #ifndef PRODUCT
 // statistics code
 class ClassStatistics: AllStatic {
  private:
   static int nclasses;        // number of classes
   static int nmethods;        // number of methods
   static int nmethoddata;     // number of methodData
   static int class_size;      // size of class objects in words
   static int method_size;     // size of method objects in words
   static int debug_size;      // size of debug info in methods
   static int methoddata_size; // size of methodData objects in words
   static void do_class(Klass* k) {
     nclasses++;
     class_size += k->size();
     if (k->oop_is_instance()) {
       InstanceKlass* ik = (InstanceKlass*)k;
       class_size += ik->methods()->size();
       class_size += ik->constants()->size();
       class_size += ik->local_interfaces()->size();
       class_size += ik->transitive_interfaces()->size();
       // We do not have to count implementors, since we only store one!
       // SSS: How should these be accounted now that they have moved?
       // class_size += ik->fields()->length();
     }
   }
   static void do_method(Method* m) {
     nmethods++;
     method_size += m->size();
     // class loader uses same objArray for empty vectors, so don't count these
     if (m->has_stackmap_table()) {
       method_size += m->stackmap_data()->size();
     }
     MethodData* mdo = m->method_data();
     if (mdo != NULL) {
       nmethoddata++;
       methoddata_size += mdo->size();
     }
   }
  public:
   static void print() {
     SystemDictionary::classes_do(do_class);
     SystemDictionary::methods_do(do_method);
     tty->print_cr("Class statistics:");
     tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
     tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
                   (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
     tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
   }
 };
 int ClassStatistics::nclasses        = 0;
 int ClassStatistics::nmethods        = 0;
 int ClassStatistics::nmethoddata     = 0;
 int ClassStatistics::class_size      = 0;
 int ClassStatistics::method_size     = 0;
 int ClassStatistics::debug_size      = 0;
 int ClassStatistics::methoddata_size = 0;
 void SystemDictionary::print_class_statistics() {
   ResourceMark rm;
   ClassStatistics::print();
 }
 class MethodStatistics: AllStatic {
  public:
   enum {
     max_parameter_size = 10
   };
  private:
   static int _number_of_methods;
   static int _number_of_final_methods;
   static int _number_of_static_methods;
   static int _number_of_native_methods;
   static int _number_of_synchronized_methods;
   static int _number_of_profiled_methods;
   static int _number_of_bytecodes;
   static int _parameter_size_profile[max_parameter_size];
   static int _bytecodes_profile[Bytecodes::number_of_java_codes];
   static void initialize() {
     _number_of_methods        = 0;
     _number_of_final_methods  = 0;
     _number_of_static_methods = 0;
     _number_of_native_methods = 0;
     _number_of_synchronized_methods = 0;
     _number_of_profiled_methods = 0;
     _number_of_bytecodes      = 0;
     for (int i = 0; i < max_parameter_size             ; i++) _parameter_size_profile[i] = 0;
     for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile     [j] = 0;
   };
   static void do_method(Method* m) {
     _number_of_methods++;
     // collect flag info
     if (m->is_final()       ) _number_of_final_methods++;
     if (m->is_static()      ) _number_of_static_methods++;
     if (m->is_native()      ) _number_of_native_methods++;
     if (m->is_synchronized()) _number_of_synchronized_methods++;
     if (m->method_data() != NULL) _number_of_profiled_methods++;
     // collect parameter size info (add one for receiver, if any)
     _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
     // collect bytecodes info
     {
       Thread *thread = Thread::current();
       HandleMark hm(thread);
       BytecodeStream s(methodHandle(thread, m));
       Bytecodes::Code c;
       while ((c = s.next()) >= 0) {
         _number_of_bytecodes++;
         _bytecodes_profile[c]++;
       }
     }
   }
  public:
   static void print() {
     initialize();
     SystemDictionary::methods_do(do_method);
     // generate output
     tty->cr();
     tty->print_cr("Method statistics (static):");
     // flag distribution
     tty->cr();
     tty->print_cr("%6d final        methods  %6.1f%%", _number_of_final_methods       , _number_of_final_methods        * 100.0F / _number_of_methods);
     tty->print_cr("%6d static       methods  %6.1f%%", _number_of_static_methods      , _number_of_static_methods       * 100.0F / _number_of_methods);
     tty->print_cr("%6d native       methods  %6.1f%%", _number_of_native_methods      , _number_of_native_methods       * 100.0F / _number_of_methods);
     tty->print_cr("%6d synchronized methods  %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
     tty->print_cr("%6d profiled     methods  %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
     // parameter size profile
     tty->cr();
     { int tot = 0;
       int avg = 0;
       for (int i = 0; i < max_parameter_size; i++) {
         int n = _parameter_size_profile[i];
         tot += n;
         avg += n*i;
         tty->print_cr("parameter size = %1d: %6d methods  %5.1f%%", i, n, n * 100.0F / _number_of_methods);
       }
       assert(tot == _number_of_methods, "should be the same");
       tty->print_cr("                    %6d methods  100.0%%", _number_of_methods);
       tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
     }
     // bytecodes profile
     tty->cr();
     { int tot = 0;
       for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
         if (Bytecodes::is_defined(i)) {
           Bytecodes::Code c = Bytecodes::cast(i);
           int n = _bytecodes_profile[c];
           tot += n;
           tty->print_cr("%9d  %7.3f%%  %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
         }
       }
       assert(tot == _number_of_bytecodes, "should be the same");
       tty->print_cr("%9d  100.000%%", _number_of_bytecodes);
     }
     tty->cr();
   }
 };
 int MethodStatistics::_number_of_methods;
 int MethodStatistics::_number_of_final_methods;
 int MethodStatistics::_number_of_static_methods;
 int MethodStatistics::_number_of_native_methods;
 int MethodStatistics::_number_of_synchronized_methods;
 int MethodStatistics::_number_of_profiled_methods;
 int MethodStatistics::_number_of_bytecodes;
 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
 void SystemDictionary::print_method_statistics() {
   MethodStatistics::print();
 }
 #endif // PRODUCT

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/classfile/systemDictionary.cpp@aefb345d3f5e (annotated)

src/share/vm/classfile/systemDictionary.cpp