systemDictionary.cpp 115.6 KB
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/*
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 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
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 * 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.
 *
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 * 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.
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 *
 */

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#include "precompiled.hpp"
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#include "classfile/classLoaderData.inline.hpp"
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#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"
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#include "compiler/compileBroker.hpp"
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#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"
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#include "oops/methodData.hpp"
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#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"
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#include "runtime/orderAccess.inline.hpp"
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#include "runtime/signature.hpp"
#include "services/classLoadingService.hpp"
#include "services/threadService.hpp"
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#include "utilities/macros.hpp"
#include "utilities/ticks.hpp"
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#if INCLUDE_TRACE
 #include "trace/tracing.hpp"
#endif

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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;
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int         SystemDictionary::_number_of_modifications = 0;
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int         SystemDictionary::_sdgeneration               = 0;
const int   SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
              20201,40423,99991};
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oop         SystemDictionary::_system_loader_lock_obj     =  NULL;

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Klass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
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                                                          =  { NULL /*, NULL...*/ };

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

bool        SystemDictionary::_has_loadClassInternal      =  false;
bool        SystemDictionary::_has_checkPackageAccess     =  false;

// lazily initialized klass variables
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Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
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// ----------------------------------------------------------------------------
// Java-level SystemLoader

oop SystemDictionary::java_system_loader() {
  return _java_system_loader;
}

void SystemDictionary::compute_java_system_loader(TRAPS) {
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  KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
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  JavaValue result(T_OBJECT);
  JavaCalls::call_static(&result,
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                         KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
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                         vmSymbols::getSystemClassLoader_name(),
                         vmSymbols::void_classloader_signature(),
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                         CHECK);

  _java_system_loader = (oop)result.get_jobject();
}


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ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
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  if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
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  return ClassLoaderDataGraph::find_or_create(class_loader, CHECK_NULL);
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}

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// ----------------------------------------------------------------------------
// debugging

#ifdef ASSERT

// return true if class_name contains no '.' (internal format is '/')
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bool SystemDictionary::is_internal_format(Symbol* class_name) {
  if (class_name != NULL) {
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    ResourceMark rm;
    char* name = class_name->as_C_string();
    return strchr(name, '.') == NULL;
  } else {
    return true;
  }
}

#endif

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// ----------------------------------------------------------------------------
// Parallel class loading check

bool SystemDictionary::is_parallelCapable(Handle class_loader) {
  if (UnsyncloadClass || class_loader.is_null()) return true;
  if (AlwaysLockClassLoader) return false;
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  return java_lang_ClassLoader::parallelCapable(class_loader());
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}
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// ----------------------------------------------------------------------------
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// ParallelDefineClass flag does not apply to bootclass loader
bool SystemDictionary::is_parallelDefine(Handle class_loader) {
   if (class_loader.is_null()) return false;
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   if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
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     return true;
   }
   return false;
}
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/**
 * Returns true if the passed class loader is the extension class loader.
 */
bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
  if (class_loader.is_null()) {
    return false;
  }
  return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
}

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// ----------------------------------------------------------------------------
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// Resolving of classes

// Forwards to resolve_or_null

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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);
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  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;
}

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Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
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  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
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    if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
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      ResourceMark rm(THREAD);
      assert(klass_h() == NULL, "Should not have result with exception pending");
      Handle e(THREAD, PENDING_EXCEPTION);
      CLEAR_PENDING_EXCEPTION;
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      THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
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    } 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) {
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      THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
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    } else {
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      THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
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    }
  }
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  return (Klass*)klass_h();
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}


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Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
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                                           bool throw_error, TRAPS)
{
  return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
}


// Forwards to resolve_instance_class_or_null

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Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
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  assert(!THREAD->is_Compiler_thread(),
         err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
                 class_name->as_C_string(),
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                 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
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  if (FieldType::is_array(class_name)) {
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    return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
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  } 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);
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  } else {
    return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
  }
}

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Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
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  return resolve_or_null(class_name, Handle(), Handle(), THREAD);
}

// Forwards to resolve_instance_class_or_null

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Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
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                                                       Handle class_loader,
                                                       Handle protection_domain,
                                                       TRAPS) {
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  assert(FieldType::is_array(class_name), "must be array");
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  Klass* k = NULL;
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  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);
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  if (t == T_OBJECT) {
    // naked oop "k" is OK here -- we assign back into it
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    k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
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                                                         class_loader,
                                                         protection_domain,
                                                         CHECK_NULL);
    if (k != NULL) {
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      k = k->array_klass(fd.dimension(), CHECK_NULL);
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    }
  } else {
    k = Universe::typeArrayKlassObj(t);
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    k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
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  }
  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
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//   resolve_instance_class_or_null:
//     via: handle_parallel_super_load
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//      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.
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Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
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                                                 Symbol* class_name,
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                                                 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
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  // (every InstanceKlass in the heap needs to be in the system dictionary
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  // 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

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  ClassLoaderData* loader_data = class_loader_data(class_loader);
  unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
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  int d_index = dictionary()->hash_to_index(d_hash);
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  unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
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  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);
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    Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
    Klass* quicksuperk;
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    // 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) &&
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       ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&
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         ((quicksuperk->name() == class_name) &&
            (quicksuperk->class_loader()  == class_loader()))) {
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           return quicksuperk;
    } else {
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      PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
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      if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
          throw_circularity_error = true;
      }
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    }
    if (!throw_circularity_error) {
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      PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
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    }
  }
  if (throw_circularity_error) {
      ResourceMark rm(THREAD);
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      THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
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  }

// java.lang.Object should have been found above
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  assert(class_name != NULL, "null super class for resolving");
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  // Resolve the super class or interface, check results on return
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  Klass* superk = SystemDictionary::resolve_or_null(class_name,
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                                                 class_loader,
                                                 protection_domain,
                                                 THREAD);

  KlassHandle superk_h(THREAD, superk);

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  // 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.
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  {
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    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();
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  }
  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();
  }

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  KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
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  JavaCalls::call_special(&result,
                         class_loader,
                         system_loader,
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                         vmSymbols::checkPackageAccess_name(),
                         vmSymbols::class_protectiondomain_signature(),
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                         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.
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    ClassLoaderData* loader_data = class_loader_data(class_loader);

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    Symbol*  kn = klass->name();
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    unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
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    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.
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      // Dictionary::do_unloading() asserts that classes in SD are only
      // unloaded at a safepoint. Anonymous classes are not in SD.
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      No_Safepoint_Verifier nosafepoint;
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      dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
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                                          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");
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  assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
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  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 -
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// to force placeholder entry creation for this class for circularity detection
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// Caller must check for pending exception
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// Returns non-null Klass* if other thread has completed load
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// and we are done,
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// If return null Klass* and no pending exception, the caller must load the class
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instanceKlassHandle SystemDictionary::handle_parallel_super_load(
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    Symbol* name, Symbol* superclassname, Handle class_loader,
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    Handle protection_domain, Handle lockObject, TRAPS) {

  instanceKlassHandle nh = instanceKlassHandle(); // null Handle
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  ClassLoaderData* loader_data = class_loader_data(class_loader);
  unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
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  int d_index = dictionary()->hash_to_index(d_hash);
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  unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
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  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.
531
  Klass* superk = SystemDictionary::resolve_super_or_fail(name,
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                                                          superclassname,
                                                          class_loader,
                                                          protection_domain,
                                                          true,
                                                          CHECK_(nh));

538 539 540
  // 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)) {
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    MutexLocker mu(SystemDictionary_lock, THREAD);
    // Check if classloading completed while we were loading superclass or waiting
543
    Klass* check = find_class(d_index, d_hash, name, loader_data);
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    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
559
    Klass* check = find_class(d_index, d_hash, name, loader_data);
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    if (check != NULL) {
      // Klass is already loaded, so just return it
      return(instanceKlassHandle(THREAD, check));
    } else {
564
      placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
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      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
577
        // If it completes we will use the resulting InstanceKlass
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        // 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);
}


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Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
                                                        Handle class_loader,
                                                        Handle protection_domain,
                                                        TRAPS) {
599 600
  assert(name != NULL && !FieldType::is_array(name) &&
         !FieldType::is_obj(name), "invalid class name");
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602
  Ticks class_load_start_time = Ticks::now();
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  // UseNewReflection
  // Fix for 4474172; see evaluation for more details
  class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
607
  ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
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  // Do lookup to see if class already exist and the protection domain
  // has the right access
611 612 613 614
  // 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
615
  unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
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  int d_index = dictionary()->hash_to_index(d_hash);
617
  Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
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                                      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
629
  // ParallelCapable Classloaders and the bootstrap classloader,
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  // or all classloaders with UnsyncloadClass do not acquire lock here
  bool DoObjectLock = true;
632
  if (is_parallelCapable(class_loader)) {
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    DoObjectLock = false;
  }

636
  unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
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  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;
651
  Symbol* superclassname = NULL;
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  {
    MutexLocker mu(SystemDictionary_lock, THREAD);
655
    Klass* check = find_class(d_index, d_hash, name, loader_data);
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    if (check != NULL) {
      // Klass is already loaded, so just return it
      class_has_been_loaded = true;
      k = instanceKlassHandle(THREAD, check);
    } else {
661
      placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
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      if (placeholder && placeholder->super_load_in_progress()) {
         super_load_in_progress = true;
         if (placeholder->havesupername() == true) {
665
           superclassname = placeholder->supername();
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           havesupername = true;
         }
      }
    }
  }

672
  // If the class is in the placeholder table, class loading is in progress
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  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;
    }
  }

684
  bool throw_circularity_error = false;
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  if (!class_has_been_loaded) {
686
    bool load_instance_added = false;
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    // 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
692 693 694
    // Redefineclasses uses existence of the placeholder for the duration
    // of the class load to prevent concurrent redefinition of not completely
    // defined classes.
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    // 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.
710 711
    // case 5. parallelCapable user level classloaders - without objectLocker
    //    Allow parallel classloading of a class/classloader pair
712

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    {
      MutexLocker mu(SystemDictionary_lock, THREAD);
715
      if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
716
        PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
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        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
736
              Klass* check = find_class(d_index, d_hash, name, loader_data);
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              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
743
              oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
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            }
          }
        }
      }
748
      // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
749
      // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
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      // LOAD_INSTANCE in parallel
751

752
      if (!throw_circularity_error && !class_has_been_loaded) {
753
        PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
754
        load_instance_added = true;
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        // 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
760
        // class loaders holding the ObjectLock shouldn't find the class here
761
        Klass* check = find_class(d_index, d_hash, name, loader_data);
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        if (check != NULL) {
763
        // Klass is already loaded, so return it after checking/adding protection domain
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          k = instanceKlassHandle(THREAD, check);
          class_has_been_loaded = true;
        }
      }
    }
769

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    // must throw error outside of owning lock
    if (throw_circularity_error) {
772
      assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
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      ResourceMark rm(THREAD);
774
      THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
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    }

    if (!class_has_been_loaded) {

      // Do actual loading
      k = load_instance_class(name, class_loader, THREAD);

782
      // For UnsyncloadClass only
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      // 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
786
      // successfully loaded InstanceKlass
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      // Should not get here for classloaders that support parallelism
788
      // with the new cleaner mechanism, even with AllowParallelDefineClass
789
      // Bootstrap goes through here to allow for an extra guarantee check
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      if (UnsyncloadClass || (class_loader.is_null())) {
        if (k.is_null() && HAS_PENDING_EXCEPTION
792
          && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
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          MutexLocker mu(SystemDictionary_lock, THREAD);
794
          Klass* check = find_class(d_index, d_hash, name, loader_data);
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          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,
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                              k, class_loader, THREAD);
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          }
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          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());
          }
        }
      }
828 829 830 831 832 833 834
    } // 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);
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      placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
      SystemDictionary_lock->notify_all();
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    }
  }

840 841 842 843
  if (HAS_PENDING_EXCEPTION || k.is_null()) {
    return NULL;
  }

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  post_class_load_event(class_load_start_time, k, class_loader);

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#ifdef ASSERT
  {
848
    ClassLoaderData* loader_data = k->class_loader_data();
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    MutexLocker mu(SystemDictionary_lock, THREAD);
850
    Klass* kk = find_class(name, loader_data);
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    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.
865 866
    // Dictionary::do_unloading() asserts that classes in SD are only
    // unloaded at a safepoint. Anonymous classes are not in SD.
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    No_Safepoint_Verifier nosafepoint;
    if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
869
                                                 loader_data,
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                                                 protection_domain)) {
      return k();
    }
  }

  // Verify protection domain. If it fails an exception is thrown
876
  validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
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  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.

893
Klass* SystemDictionary::find(Symbol* class_name,
894 895 896
                              Handle class_loader,
                              Handle protection_domain,
                              TRAPS) {
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898 899 900 901 902
  // 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()));
903 904 905 906 907 908 909
  ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());

  if (loader_data == NULL) {
    // If the ClassLoaderData has not been setup,
    // then the class loader has no entries in the dictionary.
    return NULL;
  }
910

911
  unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
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  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.
919 920
    // Dictionary::do_unloading() asserts that classes in SD are only
    // unloaded at a safepoint. Anonymous classes are not in SD.
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    No_Safepoint_Verifier nosafepoint;
922
    return dictionary()->find(d_index, d_hash, class_name, loader_data,
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                              protection_domain, THREAD);
  }
}


// Look for a loaded instance or array klass by name.  Do not do any loading.
// return NULL in case of error.
930
Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
931 932 933
                                                      Handle class_loader,
                                                      Handle protection_domain,
                                                      TRAPS) {
934
  Klass* k = NULL;
935
  assert(class_name != NULL, "class name must be non NULL");
936

937
  if (FieldType::is_array(class_name)) {
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    // The name refers to an array.  Parse the name.
939 940 941 942
    // 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));
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    if (t != T_OBJECT) {
      k = Universe::typeArrayKlassObj(t);
    } else {
946
      k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
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    }
    if (k != NULL) {
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      k = k->array_klass_or_null(fd.dimension());
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    }
  } 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?
960
Klass* SystemDictionary::parse_stream(Symbol* class_name,
961 962 963 964 965 966
                                      Handle class_loader,
                                      Handle protection_domain,
                                      ClassFileStream* st,
                                      KlassHandle host_klass,
                                      GrowableArray<Handle>* cp_patches,
                                      TRAPS) {
967
  TempNewSymbol parsed_name = NULL;
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969
  Ticks class_load_start_time = Ticks::now();
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971 972 973 974 975 976 977 978 979 980 981 982
  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());
  }

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  // 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,
990
                                                             loader_data,
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                                                             protection_domain,
992 993
                                                             host_klass,
                                                             cp_patches,
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                                                             parsed_name,
995
                                                             true,
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                                                             THREAD);


999
  if (host_klass.not_null() && k.not_null()) {
1000
    assert(EnableInvokeDynamic, "");
1001
    // If it's anonymous, initialize it now, since nobody else will.
1002 1003 1004 1005 1006 1007 1008 1009 1010

    {
      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.
1011 1012 1013

      // compiled code dependencies need to be validated anyway
      notice_modification();
1014 1015
    }

1016
    // Rewrite and patch constant pool here.
1017
    k->link_class(CHECK_NULL);
1018 1019 1020
    if (cp_patches != NULL) {
      k->constants()->patch_resolved_references(cp_patches);
    }
1021
    k->eager_initialize(CHECK_NULL);
1022 1023 1024 1025 1026 1027

    // notify jvmti
    if (JvmtiExport::should_post_class_load()) {
        assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
        JvmtiExport::post_class_load((JavaThread *) THREAD, k());
    }
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    post_class_load_event(class_load_start_time, k, class_loader);
1030
  }
1031 1032
  assert(host_klass.not_null() || cp_patches == NULL,
         "cp_patches only found with host_klass");
1033

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  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.

1042
Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1043 1044 1045 1046 1047
                                             Handle class_loader,
                                             Handle protection_domain,
                                             ClassFileStream* st,
                                             bool verify,
                                             TRAPS) {
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1049 1050 1051 1052 1053 1054 1055
  // 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;
  }

1056
  ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1057

1058
  // Make sure we are synchronized on the class loader before we proceed
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  Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
  check_loader_lock_contention(lockObject, THREAD);
1061
  ObjectLocker ol(lockObject, THREAD, DoObjectLock);
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1063
  TempNewSymbol parsed_name = NULL;
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  // 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,
1072
                                                             loader_data,
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                                                             protection_domain,
                                                             parsed_name,
1075
                                                             verify,
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                                                             THREAD);

  const char* pkg = "java/";
  if (!HAS_PENDING_EXCEPTION &&
      !class_loader.is_null() &&
1081
      parsed_name != NULL &&
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      !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) {
1101 1102
    assert(parsed_name != NULL, "Sanity");
    assert(class_name == NULL || class_name == parsed_name, "name mismatch");
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    // 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
1109
    // If a class loader supports parallel classloading handle parallel define requests
1110
    // find_or_define_instance_class may return a different InstanceKlass
1111 1112 1113 1114 1115
    if (is_parallelCapable(class_loader)) {
      k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
    } else {
      define_instance_class(k, THREAD);
    }
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  }

1118
  // Make sure we have an entry in the SystemDictionary on success
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  debug_only( {
    if (!HAS_PENDING_EXCEPTION) {
1121 1122
      assert(parsed_name != NULL, "parsed_name is still null?");
      Symbol*  h_name    = k->name();
1123
      ClassLoaderData *defining_loader_data = k->class_loader_data();
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      MutexLocker mu(SystemDictionary_lock, THREAD);

1127
      Klass* check = find_class(parsed_name, loader_data);
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      assert(check == k(), "should be present in the dictionary");

1130
      Klass* check2 = find_class(h_name, defining_loader_data);
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      assert(check == check2, "name inconsistancy in SystemDictionary");
    }
  } );

  return k();
}


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void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
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                                             int number_of_entries) {
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  assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
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         "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.

1150
Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
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  if (shared_dictionary() != NULL) {
1152
    unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1153
    int d_index = shared_dictionary()->hash_to_index(d_hash);
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    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(
1169
                 Symbol* class_name, Handle class_loader, TRAPS) {
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  instanceKlassHandle ik (THREAD, find_shared_class(class_name));
  return load_shared_class(ik, class_loader, THREAD);
}

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
1179
    Symbol*  class_name = ik->name();
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    // 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) {
1186
      Symbol*  cn = ik->super()->name();
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      resolve_super_or_fail(class_name, cn,
                            class_loader, Handle(), true, CHECK_(nh));
    }

1191
    Array<Klass*>* interfaces = ik->local_interfaces();
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    int num_interfaces = interfaces->length();
    for (int index = 0; index < num_interfaces; index++) {
1194
      Klass* k = interfaces->at(index);
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1196 1197
      // Note: can not use InstanceKlass::cast here because
      // interfaces' InstanceKlass's C++ vtbls haven't been
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      // reinitialized yet (they will be once the interface classes
      // are loaded)
1200
      Symbol*  name  = k->name();
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      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);
1218
      ik->restore_unshareable_info(CHECK_(nh));
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    }

    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
1228
    ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
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                                             true /* shared class */);
  }
  return ik;
}


1235
instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
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  instanceKlassHandle nh = instanceKlassHandle(); // null Handle
  if (class_loader.is_null()) {
1238

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    // Search the shared system dictionary for classes preloaded into the
    // shared spaces.
    instanceKlassHandle k;
1242 1243 1244 1245
    {
      PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
      k = load_shared_class(class_name, class_loader, THREAD);
    }
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    if (k.is_null()) {
      // Use VM class loader
1249
      PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
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      k = ClassLoader::load_classfile(class_name, CHECK_(nh));
    }

1253
    // find_or_define_instance_class may return a different InstanceKlass
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    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);

1262 1263 1264 1265 1266 1267 1268 1269 1270 1271
    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);

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    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);

1278
    KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
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1280 1281 1282 1283 1284 1285 1286 1287 1288 1289
    // 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
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    // custom class loaders without synchronization.
    // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1292
    // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
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    // Do NOT assume this will be supported in future releases.
1294 1295 1296 1297
    //
    // Added MustCallLoadClassInternal in case we discover in the field
    // a customer that counts on this call
    if (MustCallLoadClassInternal && has_loadClassInternal()) {
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      JavaCalls::call_special(&result,
                              class_loader,
                              spec_klass,
1301 1302
                              vmSymbols::loadClassInternal_name(),
                              vmSymbols::string_class_signature(),
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                              string,
                              CHECK_(nh));
    } else {
      JavaCalls::call_virtual(&result,
                              class_loader,
                              spec_klass,
1309 1310
                              vmSymbols::loadClass_name(),
                              vmSymbols::string_class_signature(),
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                              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 =
1322
                instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
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      // 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.
1326
      if (class_name == k->name()) {
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        return k;
      }
    }
    // Class is not found or has the wrong name, return NULL
    return nh;
  }
}

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

1337 1338 1339 1340
  ClassLoaderData* loader_data = k->class_loader_data();
  Handle class_loader_h(THREAD, loader_data->class_loader());

  for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
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1342 1343 1344 1345 1346 1347
 // 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)) {
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    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
1362
  Symbol*  name_h = k->name();
1363
  unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
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  int d_index = dictionary()->hash_to_index(d_hash);
  check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);

1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379
  // 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);
  }

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  // Add the new class. We need recompile lock during update of CHA.
  {
1382
    unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
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    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());

  }
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}

// Support parallel classloading
1408 1409 1410
// 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
1411 1412
// With AllowParallelDefine flag==true, in case they do not synchronize around
// FindLoadedClass/DefineClass, calls, we check for parallel
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// loading for them, wait if a defineClass is in progress
// and return the initial requestor's results
1415
// This flag does not apply to the bootstrap classloader.
1416 1417
// With AllowParallelDefine flag==false, call through to define_instance_class
// which will throw LinkageError: duplicate class definition.
1418
// False is the requested default.
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// For better performance, the class loaders should synchronize
1420
// findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
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// potentially waste time reading and parsing the bytestream.
// Note: VM callers should ensure consistency of k/class_name,class_loader
1423
instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
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1424 1425

  instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1426
  Symbol*  name_h = k->name(); // passed in class_name may be null
1427
  ClassLoaderData* loader_data = class_loader_data(class_loader);
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1429
  unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
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  int d_index = dictionary()->hash_to_index(d_hash);

// Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1433
  unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
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  int p_index = placeholders()->hash_to_index(p_hash);
  PlaceholderEntry* probe;

  {
    MutexLocker mu(SystemDictionary_lock, THREAD);
    // First check if class already defined
1440
    if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1441
      Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1442 1443 1444
      if (check != NULL) {
        return(instanceKlassHandle(THREAD, check));
      }
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    }

    // Acquire define token for this class/classloader
1448
    probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1449 1450 1451 1452 1453 1454 1455 1456 1457 1458
    // 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
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    if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1460
        placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1461
        SystemDictionary_lock->notify_all();
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#ifdef ASSERT
1463
        Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1464
        assert(check != NULL, "definer missed recording success");
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#endif
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        return(instanceKlassHandle(THREAD, probe->instance_klass()));
1467 1468 1469
    } else {
      // This thread will define the class (even if earlier thread tried and had an error)
      probe->set_definer(THREAD);
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    }
  }

  define_instance_class(k, THREAD);

  Handle linkage_exception = Handle(); // null handle

  // definer must notify any waiting threads
  {
    MutexLocker mu(SystemDictionary_lock, THREAD);
1480
    PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
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    assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
    if (probe != NULL) {
      if (HAS_PENDING_EXCEPTION) {
        linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
        CLEAR_PENDING_EXCEPTION;
      } else {
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        probe->set_instance_klass(k());
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      }
      probe->set_definer(NULL);
1490
      placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
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      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

1537
Klass* SystemDictionary::find_class(int index, unsigned int hash,
1538
                                      Symbol* class_name,
1539
                                      ClassLoaderData* loader_data) {
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  assert_locked_or_safepoint(SystemDictionary_lock);
1541
  assert (index == dictionary()->index_for(class_name, loader_data),
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          "incorrect index?");

1544
  Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
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  return k;
}


// Basic find on classes in the midst of being loaded
1550
Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1551
                                           ClassLoaderData* loader_data) {
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  assert_locked_or_safepoint(SystemDictionary_lock);
1553
  unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1554
  int p_index = placeholders()->hash_to_index(p_hash);
1555
  return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
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}


// Used for assertions and verification only
1560
Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
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  #ifndef ASSERT
1562 1563 1564 1565
  guarantee(VerifyBeforeGC      ||
            VerifyDuringGC      ||
            VerifyBeforeExit    ||
            VerifyDuringStartup ||
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            VerifyAfterGC, "too expensive");
  #endif
  assert_locked_or_safepoint(SystemDictionary_lock);

  // First look in the loaded class array
1571
  unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
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  int d_index = dictionary()->hash_to_index(d_hash);
1573
  return find_class(d_index, d_hash, class_name, loader_data);
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}


// Get the next class in the diictionary.
1578
Klass* SystemDictionary::try_get_next_class() {
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  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");
1590 1591
  assert_locked_or_safepoint(Compile_lock);

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  // 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
1595
  k->set_init_state(InstanceKlass::loaded);
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  // 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) {
1616
  roots_oops_do(blk, NULL);
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}

1619 1620 1621
void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
  // Follow all system classes and temporary placeholders in dictionary
  dictionary()->always_strong_classes_do(closure);
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1623 1624
  // Placeholders. These represent classes we're actively loading.
  placeholders()->classes_do(closure);
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}

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// 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;
}
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1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660
#ifdef ASSERT
class VerifySDReachableAndLiveClosure : public OopClosure {
private:
  BoolObjectClosure* _is_alive;

  template <class T> void do_oop_work(T* p) {
    oop obj = oopDesc::load_decode_heap_oop(p);
    guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
  }

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

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

1661 1662
// Assumes classes in the SystemDictionary are only unloaded at a safepoint
// Note: anonymous classes are not in the SD.
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bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
1664
  // First, mark for unload all ClassLoaderData referencing a dead class loader.
1665 1666 1667
  bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive);
  if (unloading_occurred) {
    dictionary()->do_unloading();
1668 1669
    constraints()->purge_loader_constraints();
    resolution_errors()->purge_resolution_errors();
1670 1671 1672 1673 1674 1675 1676 1677 1678
  }
  // Oops referenced by the system dictionary may get unreachable independently
  // of the class loader (eg. cached protection domain oops). So we need to
  // explicitly unlink them here instead of in Dictionary::do_unloading.
  dictionary()->unlink(is_alive);
#ifdef ASSERT
  VerifySDReachableAndLiveClosure cl(is_alive);
  dictionary()->oops_do(&cl);
#endif
1679
  return unloading_occurred;
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}

1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692
void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
  strong->do_oop(&_java_system_loader);
  strong->do_oop(&_system_loader_lock_obj);

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

  // Visit extra methods
  invoke_method_table()->oops_do(strong);
}

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void SystemDictionary::oops_do(OopClosure* f) {
  f->do_oop(&_java_system_loader);
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  f->do_oop(&_system_loader_lock_obj);
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  // Adjust dictionary
  dictionary()->oops_do(f);

1700
  // Visit extra methods
1701
  invoke_method_table()->oops_do(f);
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}

1704 1705 1706 1707 1708
// 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) {
1709
  for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1710
    f->do_klass(_well_known_klasses[k]);
1711 1712
  }

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  {
    for (int i = 0; i < T_VOID+1; i++) {
      if (_box_klasses[i] != NULL) {
        assert(i >= T_BOOLEAN, "checking");
1717
        f->do_klass(_box_klasses[i]);
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      }
    }
  }

1722
  FilteredFieldsMap::classes_do(f);
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}

1725 1726
void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
  f->do_klass(_abstract_ownable_synchronizer_klass);
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}

// Just the classes from defining class loaders
// Don't iterate over placeholders
1731
void SystemDictionary::classes_do(void f(Klass*)) {
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  dictionary()->classes_do(f);
}

// Added for initialize_itable_for_klass
//   Just the classes from defining class loaders
// Don't iterate over placeholders
1738
void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
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  dictionary()->classes_do(f, CHECK);
}

//   All classes, and their class loaders
// Don't iterate over placeholders
1744
void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
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  dictionary()->classes_do(f);
}

1748
void SystemDictionary::placeholders_do(void f(Symbol*)) {
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  placeholders()->entries_do(f);
}

1752
void SystemDictionary::methods_do(void f(Method*)) {
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  dictionary()->methods_do(f);
1754
  invoke_method_table()->methods_do(f);
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}

// ----------------------------------------------------------------------------
// 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.
1766
  Klass* aos = _abstract_ownable_synchronizer_klass;
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  if (aos == NULL) {
1768
    Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
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    // 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");
1782 1783
  _sdgeneration        = 0;
  _dictionary          = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1784
  _placeholders        = new PlaceholderTable(_nof_buckets);
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  _number_of_modifications = 0;
1786 1787 1788
  _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
  _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
  _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
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  // Allocate private object used as system class loader lock
1791
  _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
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  // Initialize basic classes
  initialize_preloaded_classes(CHECK);
}

1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810
// Compact table of directions on the initialization of klasses:
static const short wk_init_info[] = {
  #define WK_KLASS_INIT_INFO(name, symbol, option) \
    ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
          << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
      | (int)SystemDictionary::option ),
  WK_KLASSES_DO(WK_KLASS_INIT_INFO)
  #undef WK_KLASS_INIT_INFO
  0
};

bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
  assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
  int  info = wk_init_info[id - FIRST_WKID];
  int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
1811
  Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1812
  Klass**    klassp = &_well_known_klasses[id];
1813
  bool must_load = (init_opt < SystemDictionary::Opt);
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  if ((*klassp) == NULL) {
1815 1816 1817 1818 1819 1820
    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
    }
  }
1821
  return ((*klassp) != NULL);
1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833
}

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);
  }
1834 1835 1836

  // move the starting value forward to the limit:
  start_id = limit_id;
1837 1838
}

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void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1840
  assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
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  // Preload commonly used klasses
1842
  WKID scan = FIRST_WKID;
1843 1844 1845 1846 1847 1848
  // 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);
1849
    initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1850 1851 1852
  } else {
    initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
  }
1853

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  // Calculate offsets for String and Class classes since they are loaded and
  // can be used after this point.
  java_lang_String::compute_offsets();
1857
  java_lang_Class::compute_offsets();
1858

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  // 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);

1867
  // do a bunch more:
1868
  initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
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  // Preload ref klasses and set reference types
1871
  InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1872
  InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1873

1874
  initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
1875 1876 1877 1878
  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);
1879

1880 1881
  // JSR 292 classes
  WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1882
  WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1883
  initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1884
  if (EnableInvokeDynamic) {
1885 1886 1887 1888
    initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
  } else {
    // Skip the JSR 292 classes, if not enabled.
    scan = WKID(jsr292_group_end + 1);
1889
  }
1890

1891 1892
  initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);

1893 1894 1895 1896 1897 1898 1899 1900
  _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);
1901 1902 1903
  //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
  //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);

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  { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1905
    Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
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    _has_loadClassInternal = (method != NULL);
  }
  { // Compute whether we should use checkPackageAccess or NOT
1909
    Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
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    _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.
1916
BasicType SystemDictionary::box_klass_type(Klass* k) {
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  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
1931
// if initiating loader, then ok if InstanceKlass matches existing entry
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void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
                                         instanceKlassHandle k,
                                         Handle class_loader, bool defining,
                                         TRAPS) {
  const char *linkage_error = NULL;
  {
1939
    Symbol*  name  = k->name();
1940 1941
    ClassLoaderData *loader_data = class_loader_data(class_loader);

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    MutexLocker mu(SystemDictionary_lock, THREAD);

1944 1945 1946
    Klass* check = find_class(d_index, d_hash, name, loader_data);
    if (check != (Klass*)NULL) {
      // if different InstanceKlass - duplicate class definition,
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      // 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

1952
      assert(check->oop_is_instance(), "noninstance in systemdictionary");
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      if ((defining == true) || (k() != check)) {
        linkage_error = "loader (instance of  %s): attempted  duplicate class "
          "definition for name: \"%s\"";
      } else {
        return;
      }
    }

#ifdef ASSERT
1962
    Symbol* ph_check = find_placeholder(name, loader_data);
1963
    assert(ph_check == NULL || ph_check == name, "invalid symbol");
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#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);
1999
  Symbol*  name  = k->name();
2000
  ClassLoaderData *loader_data = class_loader_data(class_loader);
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  {
  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
2010
  // biasable mark word into each InstanceKlass's prototype header.
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  // 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());
    }
  }

2025
  // Make a new system dictionary entry.
2026
  Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
D
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2027
  if (sd_check == NULL) {
2028
    dictionary()->add_klass(name, loader_data, k);
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2029 2030 2031
    notice_modification();
  }
#ifdef ASSERT
2032
  sd_check = find_class(d_index, d_hash, name, loader_data);
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2033
  assert (sd_check != NULL, "should have entry in system dictionary");
2034 2035
  // Note: there may be a placeholder entry: for circularity testing
  // or for parallel defines
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2036 2037 2038 2039 2040 2041
#endif
    SystemDictionary_lock->notify_all();
  }
}


2042 2043 2044
// 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.
2045
Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2046
                    Symbol* class_name, Handle class_loader, TRAPS) {
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2047 2048 2049 2050

  // First see if it has been loaded directly.
  // Force the protection domain to be null.  (This removes protection checks.)
  Handle no_protection_domain;
2051
  Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2052
                                              no_protection_domain, CHECK_NULL);
D
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2053 2054 2055 2056 2057 2058
  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.
2059
  if (FieldType::is_array(class_name)) {
2060 2061
    // For array classes, their Klass*s are not kept in the
    // constraint table. The element Klass*s are.
2062 2063
    FieldArrayInfo fd;
    BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
D
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2064 2065 2066 2067
    if (t != T_OBJECT) {
      klass = Universe::typeArrayKlassObj(t);
    } else {
      MutexLocker mu(SystemDictionary_lock, THREAD);
2068
      klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
D
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2069
    }
2070
    // If element class already loaded, allocate array klass
D
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2071
    if (klass != NULL) {
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2072
      klass = klass->array_klass_or_null(fd.dimension());
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2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083
    }
  } 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;
}


2084
bool SystemDictionary::add_loader_constraint(Symbol* class_name,
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2085 2086 2087
                                             Handle class_loader1,
                                             Handle class_loader2,
                                             Thread* THREAD) {
2088 2089 2090
  ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
  ClassLoaderData* loader_data2 = class_loader_data(class_loader2);

2091 2092
  Symbol* constraint_name = NULL;
  if (!FieldType::is_array(class_name)) {
2093 2094
    constraint_name = class_name;
  } else {
2095
    // For array classes, their Klass*s are not kept in the
2096
    // constraint table. The element classes are.
2097 2098
    FieldArrayInfo fd;
    BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2099 2100 2101 2102
    // primitive types always pass
    if (t != T_OBJECT) {
      return true;
    } else {
2103
      constraint_name = fd.object_key();
2104 2105
    }
  }
2106
  unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
D
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2107 2108
  int d_index1 = dictionary()->hash_to_index(d_hash1);

2109
  unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
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2110 2111
  int d_index2 = dictionary()->hash_to_index(d_hash2);
  {
2112
  MutexLocker mu_s(SystemDictionary_lock, THREAD);
D
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2113

2114 2115
  // Better never do a GC while we're holding these oops
  No_Safepoint_Verifier nosafepoint;
D
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2116

2117 2118
  Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
  Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2119 2120
  return constraints()->add_entry(constraint_name, klass1, class_loader1,
                                  klass2, class_loader2);
D
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2121 2122 2123 2124 2125
  }
}

// Add entry to resolution error table to record the error when the first
// attempt to resolve a reference to a class has failed.
2126
void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {
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2127 2128 2129 2130 2131 2132 2133 2134
  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);
  }
}

2135 2136 2137 2138 2139
// 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);
}

D
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2140
// Lookup resolution error table. Returns error if found, otherwise NULL.
2141
Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
D
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2142 2143 2144 2145 2146
  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);
2147
    return (entry != NULL) ? entry->error() : (Symbol*)NULL;
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2148 2149 2150 2151
  }
}


2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196
// 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)
//
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2197 2198 2199
// 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
2200
// NULL if no constraint failed.  No exception except OOME is thrown.
2201
// Arrays are not added to the loader constraint table, their elements are.
2202
Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
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2203 2204 2205 2206 2207 2208 2209 2210 2211 2212
                                               Handle loader1, Handle loader2,
                                               bool is_method, TRAPS)  {
  // Nothing to do if loaders are the same.
  if (loader1() == loader2()) {
    return NULL;
  }

  SignatureStream sig_strm(signature, is_method);
  while (!sig_strm.is_done()) {
    if (sig_strm.is_object()) {
2213
      Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
D
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2214
      if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2215
        return sig;
D
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2216 2217 2218 2219 2220 2221 2222 2223
      }
    }
    sig_strm.next();
  }
  return NULL;
}


2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234
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);
2235
  int          index = invoke_method_table()->hash_to_index(hash);
2236 2237
  SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
  methodHandle m;
2238
  if (spe == NULL || spe->method() == NULL) {
2239
    spe = NULL;
2240
    // Must create lots of stuff here, but outside of the SystemDictionary lock.
2241
    m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2242 2243 2244
    CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier,
                                  methodHandle(), CompileThreshold, "MH", CHECK_(empty));

2245 2246
    // 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.
2247 2248 2249
    {
      MutexLocker ml(SystemDictionary_lock, THREAD);
      spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2250
      if (spe == NULL)
2251
        spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2252 2253
      if (spe->method() == NULL)
        spe->set_method(m());
2254 2255 2256
    }
  }

2257 2258
  assert(spe != NULL && spe->method() != NULL, "");
  return spe->method();
2259 2260 2261 2262
}

// Helper for unpacking the return value from linkMethod and linkCallSite.
static methodHandle unpack_method_and_appendix(Handle mname,
2263
                                               KlassHandle accessing_klass,
2264 2265 2266 2267 2268
                                               objArrayHandle appendix_box,
                                               Handle* appendix_result,
                                               TRAPS) {
  methodHandle empty;
  if (mname.not_null()) {
2269
    Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2270
    if (vmtarget != NULL && vmtarget->is_method()) {
2271
      Method* m = (Method*)vmtarget;
2272 2273 2274
      oop appendix = appendix_box->obj_at(0);
      if (TraceMethodHandles) {
    #ifndef PRODUCT
2275
        tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2276 2277 2278 2279
        m->print();
        if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
        tty->cr();
    #endif //PRODUCT
2280
      }
2281
      (*appendix_result) = Handle(THREAD, appendix);
2282 2283 2284 2285 2286 2287
      // 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
2288
      return methodHandle(THREAD, m);
2289 2290
    }
  }
2291 2292 2293 2294 2295 2296 2297
  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,
2298 2299
                                                          Handle *appendix_result,
                                                          Handle *method_type_result,
2300 2301 2302 2303 2304 2305 2306 2307
                                                          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));
2308
  }
2309

2310
  KlassHandle  mh_klass = SystemDictionary::MethodHandle_klass();
2311 2312 2313 2314 2315
  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, "");

2316 2317 2318 2319 2320
  // This should not happen.  JDK code should take care of that.
  if (accessing_klass.is_null() || method_type.is_null()) {
    THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
  }

2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335
  // 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());
2336
  (*method_type_result) = method_type;
2337
  return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2338 2339
}

2340

2341
// Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2342 2343 2344
// signature, as interpreted relative to the given class loader.
// Because of class loader constraints, all method handle usage must be
// consistent with this loader.
2345
Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2346
                                                 KlassHandle accessing_klass,
2347
                                                 TRAPS) {
2348 2349 2350 2351 2352
  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);
2353 2354 2355
  if (spe != NULL && spe->method_type() != NULL) {
    assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
    return Handle(THREAD, spe->method_type());
2356 2357 2358 2359 2360
  } 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
  }

2361 2362
  Handle class_loader, protection_domain;
  bool is_on_bcp = true;  // keep this true as long as we can materialize from the boot classloader
2363
  int npts = ArgumentCount(signature).size();
2364
  objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2365 2366
  int arg = 0;
  Handle rt;                            // the return type from the signature
2367 2368
  ResourceMark rm(THREAD);
  for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2369 2370
    oop mirror = NULL;
    if (is_on_bcp) {
2371
      // Note:  class_loader & protection_domain are both null at this point.
2372 2373 2374 2375 2376
      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()) {
2377 2378
          class_loader      = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
          protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2379 2380 2381 2382 2383 2384 2385 2386
        }
        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));
2387 2388 2389 2390 2391
    }
    if (ss.at_return_type())
      rt = Handle(THREAD, mirror);
    else
      pts->obj_at_put(arg++, mirror);
2392

2393 2394
    // Check accessibility.
    if (ss.is_object() && accessing_klass.not_null()) {
2395
      Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2396
      mirror = NULL;  // safety
2397
      // Emulate ConstantPool::verify_constant_pool_resolve.
H
hseigel 已提交
2398
      if (sel_klass->oop_is_objArray())
2399
        sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
H
hseigel 已提交
2400
      if (sel_klass->oop_is_instance()) {
2401 2402 2403 2404
        KlassHandle sel_kh(THREAD, sel_klass);
        LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
      }
    }
2405 2406 2407
  }
  assert(arg == npts, "");

2408
  // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2409 2410 2411 2412
  JavaCallArguments args(Handle(THREAD, rt()));
  args.push_oop(pts());
  JavaValue result(T_OBJECT);
  JavaCalls::call_static(&result,
2413 2414
                         SystemDictionary::MethodHandleNatives_klass(),
                         vmSymbols::findMethodHandleType_name(),
2415
                         vmSymbols::findMethodHandleType_signature(),
2416
                         &args, CHECK_(empty));
2417 2418
  Handle method_type(THREAD, (oop) result.get_jobject());

2419 2420 2421 2422 2423 2424
  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);
2425 2426
    if (spe->method_type() == NULL) {
      spe->set_method_type(method_type());
2427 2428
    }
  }
2429

2430
  // report back to the caller with the MethodType
2431
  return method_type;
2432 2433
}

2434 2435 2436 2437
// 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,
2438 2439
                                                     Symbol* name_sym,
                                                     Symbol* signature,
2440 2441
                                                     TRAPS) {
  Handle empty;
2442
  Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2443 2444
  Handle type;
  if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2445
    type = find_method_handle_type(signature, caller, CHECK_(empty));
2446 2447 2448
  } else if (caller.is_null()) {
    // This should not happen.  JDK code should take care of that.
    THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2449
  } else {
2450 2451
    ResourceMark rm(THREAD);
    SignatureStream ss(signature, false);
2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463
    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);
  }

2464
  // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2465 2466 2467 2468 2469 2470 2471 2472 2473 2474
  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(),
2475
                         vmSymbols::linkMethodHandleConstant_signature(),
2476 2477 2478
                         &args, CHECK_(empty));
  return Handle(THREAD, (oop) result.get_jobject());
}
2479

2480
// Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2481
// name and signature, as interpreted relative to the given class loader.
2482 2483 2484 2485
methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
                                                              Handle bootstrap_specifier,
                                                              Symbol* name,
                                                              Symbol* type,
2486 2487
                                                              Handle *appendix_result,
                                                              Handle *method_type_result,
2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506
                                                              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()),
2507 2508
            "caller must supply a valid BSM");

2509 2510 2511
  Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
  Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));

2512 2513 2514 2515 2516
  // This should not happen.  JDK code should take care of that.
  if (caller.is_null() || method_type.is_null()) {
    THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
  }

2517 2518
  objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
  assert(appendix_box->obj_at(0) == NULL, "");
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  // 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());
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  args.push_oop(info());
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  args.push_oop(appendix_box);
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  JavaValue result(T_OBJECT);
  JavaCalls::call_static(&result,
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                         SystemDictionary::MethodHandleNatives_klass(),
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                         vmSymbols::linkCallSite_name(),
                         vmSymbols::linkCallSite_signature(),
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                         &args, CHECK_(empty));
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  Handle mname(THREAD, (oop) result.get_jobject());
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  (*method_type_result) = method_type;
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  return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
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}

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// 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");
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  constraints()->verify(dictionary(), placeholders());
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}

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// utility function for class load event
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void SystemDictionary::post_class_load_event(const Ticks& start_time,
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                                             instanceKlassHandle k,
                                             Handle initiating_loader) {
#if INCLUDE_TRACE
  EventClassLoad event(UNTIMED);
  if (event.should_commit()) {
    event.set_starttime(start_time);
    event.set_loadedClass(k());
    oop defining_class_loader = k->class_loader();
    event.set_definingClassLoader(defining_class_loader !=  NULL ?
                                    defining_class_loader->klass() : (Klass*)NULL);
    oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
    event.set_initiatingClassLoader(class_loader != NULL ?
                                      class_loader->klass() : (Klass*)NULL);
    event.commit();
  }
#endif /* INCLUDE_TRACE */
}

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#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

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  static void do_class(Klass* k) {
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    nclasses++;
    class_size += k->size();
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    if (k->oop_is_instance()) {
      InstanceKlass* ik = (InstanceKlass*)k;
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      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!
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      // SSS: How should these be accounted now that they have moved?
      // class_size += ik->fields()->length();
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    }
  }

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  static void do_method(Method* m) {
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    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();
    }

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    MethodData* mdo = m->method_data();
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    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;
  };

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  static void do_method(Method* m) {
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    _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