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systemDictionary.cpp 
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/*
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 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "cds/cdsConfig.hpp"
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#include "cds/heapShared.hpp"
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#include "classfile/classFileParser.hpp"
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#include "classfile/classFileStream.hpp"
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#include "classfile/classLoader.hpp"
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#include "classfile/classLoaderData.inline.hpp"
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#include "classfile/classLoaderDataGraph.inline.hpp"
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#include "classfile/classLoaderExt.hpp"
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#include "classfile/classLoadInfo.hpp"
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#include "classfile/dictionary.hpp"
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#include "classfile/javaClasses.inline.hpp"
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#include "classfile/klassFactory.hpp"
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#include "classfile/loaderConstraints.hpp"
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#include "classfile/packageEntry.hpp"
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#include "classfile/placeholders.hpp"
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#include "classfile/protectionDomainCache.hpp"
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#include "classfile/resolutionErrors.hpp"
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#include "classfile/stringTable.hpp"
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#include "classfile/symbolTable.hpp"
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#include "classfile/systemDictionary.hpp"
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#include "classfile/vmClasses.hpp"
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#include "classfile/vmSymbols.hpp"
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#include "gc/shared/gcTraceTime.inline.hpp"
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#include "interpreter/bootstrapInfo.hpp"
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#include "jfr/jfrEvents.hpp"
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#include "jvm.h"
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#include "logging/log.hpp"
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#include "logging/logStream.hpp"
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#include "memory/metaspaceClosure.hpp"
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#include "memory/oopFactory.hpp"
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#include "memory/resourceArea.hpp"
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#include "memory/universe.hpp"
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#include "oops/access.inline.hpp"
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#include "oops/instanceKlass.hpp"
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#include "oops/klass.inline.hpp"
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#include "oops/method.inline.hpp"
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#include "oops/objArrayKlass.hpp"
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#include "oops/objArrayOop.inline.hpp"
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#include "oops/oop.inline.hpp"
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#include "oops/oop.hpp"
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#include "oops/oopHandle.hpp"
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#include "oops/oopHandle.inline.hpp"
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#include "oops/symbol.hpp"
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#include "oops/typeArrayKlass.hpp"
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#include "prims/jvmtiExport.hpp"
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#include "prims/methodHandles.hpp"
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#include "runtime/arguments.hpp"
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#include "runtime/atomic.hpp"
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#include "runtime/handles.inline.hpp"
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#include "runtime/java.hpp"
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#include "runtime/javaCalls.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "runtime/sharedRuntime.hpp"
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#include "runtime/signature.hpp"
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#include "runtime/synchronizer.hpp"
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#include "services/classLoadingService.hpp"
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#include "services/diagnosticCommand.hpp"
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#include "services/finalizerService.hpp"
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#include "services/threadService.hpp"
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#include "utilities/macros.hpp"
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#include "utilities/utf8.hpp"
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#if INCLUDE_CDS
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#include "classfile/systemDictionaryShared.hpp"
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#endif
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#if INCLUDE_JFR
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#include "jfr/jfr.hpp"
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#endif
93

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class InvokeMethodKey : public StackObj {
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  private:
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    Symbol* _symbol;
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    intptr_t _iid;
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  public:
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    InvokeMethodKey(Symbol* symbol, intptr_t iid) :
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        _symbol(symbol),
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        _iid(iid) {}
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    static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
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        return k1._symbol == k2._symbol && k1._iid == k2._iid;
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    }
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    static unsigned int compute_hash(const InvokeMethodKey &k) {
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        Symbol* sym = k._symbol;
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        intptr_t iid = k._iid;
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        unsigned int hash = (unsigned int) sym -> identity_hash();
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        return (unsigned int) (hash ^ iid);
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    }
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};
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using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
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                  InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
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static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
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using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
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static InvokeMethodTypeTable* _invoke_method_type_table;
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OopHandle   SystemDictionary::_java_system_loader;
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OopHandle   SystemDictionary::_java_platform_loader;
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// ----------------------------------------------------------------------------
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// Java-level SystemLoader and PlatformLoader
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oop SystemDictionary::java_system_loader() {
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  return _java_system_loader.resolve();
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}
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oop SystemDictionary::java_platform_loader() {
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  return _java_platform_loader.resolve();
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}
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void SystemDictionary::compute_java_loaders(TRAPS) {
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  if (_java_system_loader.is_empty()) {
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    oop system_loader = get_system_class_loader_impl(CHECK);
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    _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
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  } else {
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    // It must have been restored from the archived module graph
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    assert(CDSConfig::is_using_archive(), "must be");
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    assert(CDSConfig::is_using_full_module_graph(), "must be");
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    DEBUG_ONLY(
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      oop system_loader = get_system_class_loader_impl(CHECK);
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      assert(_java_system_loader.resolve() == system_loader, "must be");
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    )
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 }
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150
  if (_java_platform_loader.is_empty()) {
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    oop platform_loader = get_platform_class_loader_impl(CHECK);
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    _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
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  } else {
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    // It must have been restored from the archived module graph
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    assert(CDSConfig::is_using_archive(), "must be");
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    assert(CDSConfig::is_using_full_module_graph(), "must be");
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    DEBUG_ONLY(
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      oop platform_loader = get_platform_class_loader_impl(CHECK);
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      assert(_java_platform_loader.resolve() == platform_loader, "must be");
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    )
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  }
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}
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oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
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  JavaValue result(T_OBJECT);
166
  InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
167
  JavaCalls::call_static(&result,
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                         class_loader_klass,
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                         vmSymbols::getSystemClassLoader_name(),
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                         vmSymbols::void_classloader_signature(),
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                         CHECK_NULL);
172
  return result.get_oop();
173
}
174

175
oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
176
  JavaValue result(T_OBJECT);
177
  InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
178
  JavaCalls::call_static(&result,
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                         class_loader_klass,
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                         vmSymbols::getPlatformClassLoader_name(),
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                         vmSymbols::void_classloader_signature(),
182
                         CHECK_NULL);
183
  return result.get_oop();
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}
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186
// Helper function
187
inline ClassLoaderData* class_loader_data(Handle class_loader) {
188
  return ClassLoaderData::class_loader_data(class_loader());
189
}
190

191
ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
192
  if (create_mirror_cld) {
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    // Add a new class loader data to the graph.
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    return ClassLoaderDataGraph::add(class_loader, true);
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  } else {
196
    return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
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                                      ClassLoaderDataGraph::find_or_create(class_loader);
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  }
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}
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void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
202
  assert(_java_system_loader.is_empty(), "already set!");
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  _java_system_loader = cld->class_loader_handle();
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205
}
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void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
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  assert(_java_platform_loader.is_empty(), "already set!");
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  _java_platform_loader = cld->class_loader_handle();
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}
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212
// ----------------------------------------------------------------------------
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// Parallel class loading check
214

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static bool is_parallelCapable(Handle class_loader) {
216
  if (class_loader.is_null()) return true;
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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
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static bool is_parallelDefine(Handle class_loader) {
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   if (class_loader.is_null()) return false;
223
   if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
224
     return true;
225
   }
226
   return false;
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}
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// Returns true if the passed class loader is the builtin application class loader
230
// or a custom system class loader. A customer system class loader can be
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// specified via -Djava.system.class.loader.
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bool SystemDictionary::is_system_class_loader(oop class_loader) {
233
  if (class_loader == nullptr) {
234
    return false;
235
  }
236
  return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
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         class_loader == _java_system_loader.peek());
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}
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// Returns true if the passed class loader is the platform class loader.
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bool SystemDictionary::is_platform_class_loader(oop class_loader) {
242
  if (class_loader == nullptr) {
243
    return false;
244
  }
245
  return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
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}
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Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
249
  // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
250
  if (is_parallelCapable(class_loader)) {
251
    return Handle();
252
  } else {
253
    return class_loader;
254
  }
255
}
256

257
// ----------------------------------------------------------------------------
258
// Resolving of classes
259

260
Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
261
  if (name == nullptr) {
262
    THROW_MSG_0(exception, "No class name given");
263
  }
264
  if ((int)strlen(name) > Symbol::max_length()) {
265
    // It's impossible to create this class;  the name cannot fit
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    // into the constant pool.
267
    Exceptions::fthrow(THREAD_AND_LOCATION, exception,
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                       "Class name exceeds maximum length of %d: %s",
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                       Symbol::max_length(),
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                       name);
271
    return nullptr;
272
  }
273
  // Callers should ensure that the name is never an illegal UTF8 string.
274
  assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
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         "Class name is not a valid utf8 string.");
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277
  // Make a new symbol for the class name.
278
  return SymbolTable::new_symbol(name);
279
}
280

281
#ifdef ASSERT
282
// Used to verify that class loading succeeded in adding k to the dictionary.
283
static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
284
  MutexLocker mu(SystemDictionary_lock);
285
  ClassLoaderData* loader_data = k->class_loader_data();
286
  Dictionary* dictionary = loader_data->dictionary();
287
  assert(class_name == k->name(), "Must be the same");
288
  InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
289
  assert(kk == k, "should be present in dictionary");
290
}
291
#endif
292

293
static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
294
  if (HAS_PENDING_EXCEPTION) {
295
    // If we have a pending exception we forward it to the caller, unless throw_error is true,
296
    // in which case we have to check whether the pending exception is a ClassNotFoundException,
297
    // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
298
    if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
299
      ResourceMark rm(THREAD);
300
      Handle e(THREAD, PENDING_EXCEPTION);
301
      CLEAR_PENDING_EXCEPTION;
302
      THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
303
    } else {
304
      return; // the caller will throw the incoming exception
305
    }
306
  }
307
  // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
308
  // error or exception depending on the value of throw_error.
309
  ResourceMark rm(THREAD);
310
  if (throw_error) {
311
    THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
312
  } else {
313
    THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
314
  }
315
}
316

317
// Forwards to resolve_or_null
318

319
Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
320
                                         bool throw_error, TRAPS) {
321
  Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
322
  // Check for pending exception or null klass, and throw exception
323
  if (HAS_PENDING_EXCEPTION || klass == nullptr) {
324
    handle_resolution_exception(class_name, throw_error, CHECK_NULL);
325
  }
326
  return klass;
327
}
328

329
// Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
330

331
Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
332
  if (Signature::is_array(class_name)) {
333
    return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
334
  } else {
335
    assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
336
    if (Signature::has_envelope(class_name)) {
337
      ResourceMark rm(THREAD);
338
      // Ignore wrapping L and ;.
339
      TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
340
                                                   class_name->utf8_length() - 2);
341
      return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
342
    } else {
343
      return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
344
    }
345
  }
346
}
347

348
// Forwards to resolve_instance_class_or_null
349

350
Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
351
                                                     Handle class_loader,
352
                                                     Handle protection_domain,
353
                                                     TRAPS) {
354
  assert(Signature::is_array(class_name), "must be array");
355
  ResourceMark rm(THREAD);
356
  SignatureStream ss(class_name, false);
357
  int ndims = ss.skip_array_prefix();  // skip all '['s
358
  Klass* k = nullptr;
359
  BasicType t = ss.type();
360
  if (ss.has_envelope()) {
361
    Symbol* obj_class = ss.as_symbol();
362
    k = SystemDictionary::resolve_instance_class_or_null(obj_class,
363
                                                         class_loader,
364
                                                         protection_domain,
365
                                                         CHECK_NULL);
366
    if (k != nullptr) {
367
      k = k->array_klass(ndims, CHECK_NULL);
368
    }
369
  } else {
370
    k = Universe::typeArrayKlass(t);
371
    k = k->array_klass(ndims, CHECK_NULL);
372
  }
373
  return k;
374
}
375

376
static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
377
  LogTarget(Debug, class, load, placeholders) lt;
378
  if (lt.is_enabled()) {
379
    ResourceMark rm;
380
    LogStream ls(lt);
381
    ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
382
    probe->print_on(&ls);
383
    ls.cr();
384
  }
385
}
386

387
// Must be called for any superclass or superinterface resolution
388
// during class definition to allow class circularity checking
389
// superinterface callers:
390
//    parse_interfaces - from defineClass
391
// superclass callers:
392
//   ClassFileParser - from defineClass
393
//   load_shared_class - while loading a class from shared archive
394
//   resolve_instance_class_or_null:
395
//     via: handle_parallel_super_load
396
//      when resolving a class that has an existing placeholder with
397
//      a saved superclass [i.e. a defineClass is currently in progress]
398
//      If another thread is trying to resolve the class, it must do
399
//      superclass checks on its own thread to catch class circularity and
400
//      to avoid deadlock.
401
//
402
// resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
403
// resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
404
// placeholder for the same thread, class, classloader is found.
405
// This can be seen with logging option: -Xlog:class+load+placeholders=debug.
406
//
407
InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
408
                                                       Symbol* super_name,
409
                                                       Handle class_loader,
410
                                                       Handle protection_domain,
411
                                                       bool is_superclass,
412
                                                       TRAPS) {
413

414
  assert(super_name != nullptr, "null superclass for resolving");
415
  assert(!Signature::is_array(super_name), "invalid superclass name");
416
#if INCLUDE_CDS
417
  if (CDSConfig::is_dumping_static_archive()) {
418
    // Special processing for handling UNREGISTERED shared classes.
419
    InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
420
                           super_name, is_superclass);
421
    if (k) {
422
      return k;
423
    }
424
  }
425
#endif // INCLUDE_CDS
426

427
  // If klass is already loaded, just return the superclass or superinterface.
428
  // Make sure there's a placeholder for the class_name before resolving.
429
  // This is used as a claim that this thread is currently loading superclass/classloader
430
  // and for ClassCircularity checks.
431

432
  ClassLoaderData* loader_data = class_loader_data(class_loader);
433
  Dictionary* dictionary = loader_data->dictionary();
434

435
  // can't throw error holding a lock
436
  bool throw_circularity_error = false;
437
  {
438
    MutexLocker mu(THREAD, SystemDictionary_lock);
439
    InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
440
    InstanceKlass* quicksuperk;
441
    // To support parallel loading: if class is done loading, just return the superclass
442
    // if the super_name matches class->super()->name() and if the class loaders match.
443
    // Otherwise, a LinkageError will be thrown later.
444
    if (klassk != nullptr && is_superclass &&
445
        ((quicksuperk = klassk->java_super()) != nullptr) &&
446
         ((quicksuperk->name() == super_name) &&
447
            (quicksuperk->class_loader() == class_loader()))) {
448
           return quicksuperk;
449
    } else {
450
      // Must check ClassCircularity before checking if superclass is already loaded.
451
      PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
452
      if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
453
          log_circularity_error(class_name, probe);
454
          throw_circularity_error = true;
455
      }
456
    }
457

458
    if (!throw_circularity_error) {
459
      // Be careful not to exit resolve_super without removing this placeholder.
460
      PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
461
                                                                  loader_data,
462
                                                                  PlaceholderTable::LOAD_SUPER,
463
                                                                  super_name, THREAD);
464
    }
465
  }
466

467
  if (throw_circularity_error) {
468
      ResourceMark rm(THREAD);
469
      THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
470
  }
471

472
  // Resolve the superclass or superinterface, check results on return
473
  InstanceKlass* superk =
474
    SystemDictionary::resolve_instance_class_or_null(super_name,
475
                                                     class_loader,
476
                                                     protection_domain,
477
                                                     THREAD);
478

479
  // Clean up placeholder entry.
480
  {
481
    MutexLocker mu(THREAD, SystemDictionary_lock);
482
    PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
483
    SystemDictionary_lock->notify_all();
484
  }
485

486
  // Check for pending exception or null superk, and throw exception
487
  if (HAS_PENDING_EXCEPTION || superk == nullptr) {
488
    handle_resolution_exception(super_name, true, CHECK_NULL);
489
  }
490

491
  return superk;
492
}
493

494
// If the class in is in the placeholder table, class loading is in progress.
495
// For cases where the application changes threads to load classes, it
496
// is critical to ClassCircularity detection that we try loading
497
// the superclass on the new thread internally, so we do parallel
498
// superclass loading here.  This avoids deadlock for ClassCircularity
499
// detection for parallelCapable class loaders that lock on a per-class lock.
500
static void handle_parallel_super_load(Symbol* name,
501
                                       Symbol* superclassname,
502
                                       Handle class_loader,
503
                                       Handle protection_domain, TRAPS) {
504

505
  // superk is not used; resolve_super_or_fail is called for circularity check only.
506
  Klass* superk = SystemDictionary::resolve_super_or_fail(name,
507
                                                          superclassname,
508
                                                          class_loader,
509
                                                          protection_domain,
510
                                                          true,
511
                                                          CHECK);
512
}
513

514
// Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
515
// wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
516
static bool needs_load_placeholder(Handle class_loader) {
517
  return class_loader.is_null() || !is_parallelCapable(class_loader);
518
}
519

520
// Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
521
static InstanceKlass* handle_parallel_loading(JavaThread* current,
522
                                              Symbol* name,
523
                                              ClassLoaderData* loader_data,
524
                                              bool must_wait_for_class_loading,
525
                                              bool* throw_circularity_error) {
526
  PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
527
  if (oldprobe != nullptr) {
528
    // -Xcomp calls load_signature_classes which might result in loading
529
    // a class that's already in the process of loading, so we detect CCE here also.
530
    // Only need check_seen_thread once, not on each loop
531
    if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
532
      log_circularity_error(name, oldprobe);
533
      *throw_circularity_error = true;
534
      return nullptr;
535
    } else if (must_wait_for_class_loading) {
536
      // Wait until the first thread has finished loading this class. Also wait until all the
537
      // threads trying to load its superclass have removed their placeholders.
538
      while (oldprobe != nullptr &&
539
             (oldprobe->instance_load_in_progress() || oldprobe->super_load_in_progress())) {
540

541
        // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
542
        // for the bootclass loader.
543
        SystemDictionary_lock->wait();
544

545
        // Check if classloading completed while we were waiting
546
        InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
547
        if (check != nullptr) {
548
          // Klass is already loaded, so just return it
549
          return check;
550
        }
551
        // check if other thread failed to load and cleaned up
552
        oldprobe = PlaceholderTable::get_entry(name, loader_data);
553
      }
554
    }
555
  }
556
  return nullptr;
557
}
558

559
void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
560
  assert(event != nullptr, "invariant");
561
  assert(k != nullptr, "invariant");
562
  event->set_loadedClass(k);
563
  event->set_definingClassLoader(k->class_loader_data());
564
  event->set_initiatingClassLoader(init_cld);
565
  event->commit();
566
}
567

568
// SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
569
// After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
570
// whether the thread must wait for loading in parallel.  It eventually calls load_instance_class,
571
// which will load the class via the bootstrap loader or call ClassLoader.loadClass().
572
// This can return null, an exception or an InstanceKlass.
573
InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
574
                                                                Handle class_loader,
575
                                                                Handle protection_domain,
576
                                                                TRAPS) {
577
  // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
578
  assert(name != nullptr && !Signature::is_array(name) &&
579
         !Signature::has_envelope(name), "invalid class name");
580

581
  EventClassLoad class_load_start_event;
582

583
  HandleMark hm(THREAD);
584

585
  // Fix for 4474172; see evaluation for more details
586
  class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
587
  ClassLoaderData* loader_data = register_loader(class_loader);
588
  Dictionary* dictionary = loader_data->dictionary();
589

590
  // Do lookup to see if class already exists and the protection domain
591
  // has the right access.
592
  // This call uses find which checks protection domain already matches
593
  // All subsequent calls use find_class, and set loaded_class so that
594
  // before we return a result, we call out to java to check for valid protection domain.
595
  InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
596
  if (probe != nullptr) return probe;
597

598
  // Non-bootstrap class loaders will call out to class loader and
599
  // define via jvm/jni_DefineClass which will acquire the
600
  // class loader object lock to protect against multiple threads
601
  // defining the class in parallel by accident.
602
  // This lock must be acquired here so the waiter will find
603
  // any successful result in the SystemDictionary and not attempt
604
  // the define.
605
  // ParallelCapable class loaders and the bootstrap classloader
606
  // do not acquire lock here.
607
  Handle lockObject = get_loader_lock_or_null(class_loader);
608
  ObjectLocker ol(lockObject, THREAD);
609

610
  bool super_load_in_progress  = false;
611
  InstanceKlass* loaded_class = nullptr;
612
  SymbolHandle superclassname; // Keep alive while loading in parallel thread.
613

614
  guarantee(THREAD->can_call_java(),
615
         "can not load classes with compiler thread: class=%s, classloader=%s",
616
         name->as_C_string(),
617
         class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
618

619
  // Check again (after locking) if the class already exists in SystemDictionary
620
  {
621
    MutexLocker mu(THREAD, SystemDictionary_lock);
622
    InstanceKlass* check = dictionary->find_class(THREAD, name);
623
    if (check != nullptr) {
624
      // InstanceKlass is already loaded, but we still need to check protection domain below.
625
      loaded_class = check;
626
    } else {
627
      PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
628
      if (placeholder != nullptr && placeholder->super_load_in_progress()) {
629
         super_load_in_progress = true;
630
         superclassname = placeholder->supername();
631
         assert(superclassname != nullptr, "superclass has to have a name");
632
      }
633
    }
634
  }
635

636
  // If the class is in the placeholder table with super_class set,
637
  // handle superclass loading in progress.
638
  if (super_load_in_progress) {
639
    handle_parallel_super_load(name, superclassname,
640
                               class_loader,
641
                               protection_domain,
642
                               CHECK_NULL);
643
  }
644

645
  bool throw_circularity_error = false;
646
  if (loaded_class == nullptr) {
647
    bool load_placeholder_added = false;
648

649
    // Add placeholder entry to record loading instance class
650
    // case 1. Bootstrap classloader
651
    //    This classloader supports parallelism at the classloader level
652
    //    but only allows a single thread to load a class/classloader pair.
653
    //    The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
654
    // case 2. parallelCapable user level classloaders
655
    //    These class loaders lock a per-class object lock when ClassLoader.loadClass()
656
    //    is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
657
    // case 3. traditional classloaders that rely on the classloader object lock
658
    //    There should be no need for need for LOAD_INSTANCE for mutual exclusion,
659
    //    except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
660
    //    TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
661
    {
662
      MutexLocker mu(THREAD, SystemDictionary_lock);
663
      if (needs_load_placeholder(class_loader)) {
664
        loaded_class = handle_parallel_loading(THREAD,
665
                                               name,
666
                                               loader_data,
667
                                               class_loader.is_null(),
668
                                               &throw_circularity_error);
669
      }
670

671
      // Recheck if the class has been loaded for all class loader cases and
672
      // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
673
      if (!throw_circularity_error && loaded_class == nullptr) {
674
        InstanceKlass* check = dictionary->find_class(THREAD, name);
675
        if (check != nullptr) {
676
          loaded_class = check;
677
        } else if (needs_load_placeholder(class_loader)) {
678
          // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
679
          PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
680
                                                                      PlaceholderTable::LOAD_INSTANCE,
681
                                                                      nullptr,
682
                                                                      THREAD);
683
          load_placeholder_added = true;
684
        }
685
      }
686
    }
687

688
    // Must throw error outside of owning lock
689
    if (throw_circularity_error) {
690
      assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
691
      ResourceMark rm(THREAD);
692
      THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
693
    }
694

695
    // Be careful when modifying this code: once you have run
696
    // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
697
    // you need to find_and_remove it before returning.
698
    // So be careful to not exit with a CHECK_ macro between these calls.
699

700
    if (loaded_class == nullptr) {
701
      // Do actual loading
702
      loaded_class = load_instance_class(name, class_loader, THREAD);
703
    }
704

705
    if (load_placeholder_added) {
706
      // clean up placeholder entries for LOAD_INSTANCE success or error
707
      // This brackets the SystemDictionary updates for both defining
708
      // and initiating loaders
709
      MutexLocker mu(THREAD, SystemDictionary_lock);
710
      PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
711
      SystemDictionary_lock->notify_all();
712
    }
713
  }
714

715
  if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
716
    return nullptr;
717
  }
718

719
  if (class_load_start_event.should_commit()) {
720
    post_class_load_event(&class_load_start_event, loaded_class, loader_data);
721
  }
722

723
  // Make sure we have the right class in the dictionary
724
  DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
725

726
  if (protection_domain() != nullptr) {
727
    // A SecurityManager (if installed) may prevent this protection_domain from accessing loaded_class
728
    // by throwing a SecurityException.
729
    dictionary->check_package_access(loaded_class, class_loader, protection_domain, CHECK_NULL);
730
  }
731

732
  return loaded_class;
733
}
734

735

736
// This routine does not lock the system dictionary.
737
//
738
// Since readers don't hold a lock, we must make sure that system
739
// dictionary entries are added to in a safe way (all links must
740
// be updated in an MT-safe manner). All entries are removed during class
741
// unloading, when this class loader is no longer referenced.
742
//
743
// Callers should be aware that an entry could be added just after
744
// Dictionary is read here, so the caller will not see
745
// the new entry.
746

747
InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
748
                                                     Symbol* class_name,
749
                                                     Handle class_loader,
750
                                                     Handle protection_domain) {
751

752
  // The result of this call should be consistent with the result
753
  // of the call to resolve_instance_class_or_null().
754
  // See evaluation 6790209 and 4474172 for more details.
755
  oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
756
  ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
757

758
  if (loader_data == nullptr) {
759
    // If the ClassLoaderData has not been setup,
760
    // then the class loader has no entries in the dictionary.
761
    return nullptr;
762
  }
763

764
  Dictionary* dictionary = loader_data->dictionary();
765
  return dictionary->find(current, class_name, protection_domain);
766
}
767

768
// Look for a loaded instance or array klass by name.  Do not do any loading.
769
// return null in case of error.
770
Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
771
                                                      Symbol* class_name,
772
                                                      Handle class_loader,
773
                                                      Handle protection_domain) {
774
  Klass* k = nullptr;
775
  assert(class_name != nullptr, "class name must be non nullptr");
776

777
  if (Signature::is_array(class_name)) {
778
    // The name refers to an array.  Parse the name.
779
    // dimension and object_key in FieldArrayInfo are assigned as a
780
    // side-effect of this call
781
    SignatureStream ss(class_name, false);
782
    int ndims = ss.skip_array_prefix();  // skip all '['s
783
    BasicType t = ss.type();
784
    if (t != T_OBJECT) {
785
      k = Universe::typeArrayKlass(t);
786
    } else {
787
      k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
788
    }
789
    if (k != nullptr) {
790
      k = k->array_klass_or_null(ndims);
791
    }
792
  } else {
793
    k = find_instance_klass(current, class_name, class_loader, protection_domain);
794
  }
795
  return k;
796
}
797

798
// Note: this method is much like resolve_class_from_stream, but
799
// does not publish the classes in the SystemDictionary.
800
// Handles Lookup.defineClass hidden.
801
InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
802
                                                     ClassFileStream* st,
803
                                                     Symbol* class_name,
804
                                                     Handle class_loader,
805
                                                     const ClassLoadInfo& cl_info,
806
                                                     TRAPS) {
807

808
  EventClassLoad class_load_start_event;
809
  ClassLoaderData* loader_data;
810

811
  // - for hidden classes that are not strong: create a new CLD that has a class holder and
812
  //                                           whose loader is the Lookup class's loader.
813
  // - for hidden class: add the class to the Lookup class's loader's CLD.
814
  assert (cl_info.is_hidden(), "only used for hidden classes");
815
  bool create_mirror_cld = !cl_info.is_strong_hidden();
816
  loader_data = register_loader(class_loader, create_mirror_cld);
817

818
  assert(st != nullptr, "invariant");
819
  assert(st->need_verify(), "invariant");
820

821
  // Parse stream and create a klass.
822
  InstanceKlass* k = KlassFactory::create_from_stream(st,
823
                                                      class_name,
824
                                                      loader_data,
825
                                                      cl_info,
826
                                                      CHECK_NULL);
827
  assert(k != nullptr, "no klass created");
828

829
  // Hidden classes that are not strong must update ClassLoaderData holder
830
  // so that they can be unloaded when the mirror is no longer referenced.
831
  if (!cl_info.is_strong_hidden()) {
832
    k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
833
  }
834

835
  // Add to class hierarchy, and do possible deoptimizations.
836
  k->add_to_hierarchy(THREAD);
837
  // But, do not add to dictionary.
838

839
  k->link_class(CHECK_NULL);
840

841
  // notify jvmti
842
  if (JvmtiExport::should_post_class_load()) {
843
    JvmtiExport::post_class_load(THREAD, k);
844
  }
845
  if (class_load_start_event.should_commit()) {
846
    post_class_load_event(&class_load_start_event, k, loader_data);
847
  }
848

849
  return k;
850
}
851

852
// Add a klass to the system from a stream (called by jni_DefineClass and
853
// JVM_DefineClass).
854
// Note: class_name can be null. In that case we do not know the name of
855
// the class until we have parsed the stream.
856
// This function either returns an InstanceKlass or throws an exception.  It does
857
// not return null without a pending exception.
858
InstanceKlass* SystemDictionary::resolve_class_from_stream(
859
                                                     ClassFileStream* st,
860
                                                     Symbol* class_name,
861
                                                     Handle class_loader,
862
                                                     const ClassLoadInfo& cl_info,
863
                                                     TRAPS) {
864

865
  HandleMark hm(THREAD);
866

867
  ClassLoaderData* loader_data = register_loader(class_loader);
868

869
  // Classloaders that support parallelism, e.g. bootstrap classloader,
870
  // do not acquire lock here
871
  Handle lockObject = get_loader_lock_or_null(class_loader);
872
  ObjectLocker ol(lockObject, THREAD);
873

874
  // Parse the stream and create a klass.
875
  // Note that we do this even though this klass might
876
  // already be present in the SystemDictionary, otherwise we would not
877
  // throw potential ClassFormatErrors.
878
 InstanceKlass* k = nullptr;
879

880
#if INCLUDE_CDS
881
  if (!CDSConfig::is_dumping_static_archive()) {
882
    k = SystemDictionaryShared::lookup_from_stream(class_name,
883
                                                   class_loader,
884
                                                   cl_info.protection_domain(),
885
                                                   st,
886
                                                   CHECK_NULL);
887
  }
888
#endif
889

890
  if (k == nullptr) {
891
    k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
892
  }
893

894
  assert(k != nullptr, "no klass created");
895
  Symbol* h_name = k->name();
896
  assert(class_name == nullptr || class_name == h_name, "name mismatch");
897

898
  // Add class just loaded
899
  // If a class loader supports parallel classloading, handle parallel define requests.
900
  // find_or_define_instance_class may return a different InstanceKlass,
901
  // in which case the old k would be deallocated
902
  if (is_parallelCapable(class_loader)) {
903
    k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
904
  } else {
905
    define_instance_class(k, class_loader, THREAD);
906

907
    // If defining the class throws an exception register 'k' for cleanup.
908
    if (HAS_PENDING_EXCEPTION) {
909
      assert(k != nullptr, "Must have an instance klass here!");
910
      loader_data->add_to_deallocate_list(k);
911
      return nullptr;
912
    }
913
  }
914

915
  // Make sure we have an entry in the SystemDictionary on success
916
  DEBUG_ONLY(verify_dictionary_entry(h_name, k));
917

918
  return k;
919
}
920

921
InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
922
                                                     Symbol* class_name,
923
                                                     Handle class_loader,
924
                                                     const ClassLoadInfo& cl_info,
925
                                                     TRAPS) {
926
  if (cl_info.is_hidden()) {
927
    return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
928
  } else {
929
    return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
930
  }
931
}
932

933

934
#if INCLUDE_CDS
935
// Check if a shared class can be loaded by the specific classloader.
936
bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
937
                                               InstanceKlass* ik,
938
                                               PackageEntry* pkg_entry,
939
                                               Handle class_loader) {
940
  assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
941
         "Cannot use sharing if java.base is patched");
942

943
  // (1) Check if we are loading into the same loader as in dump time.
944

945
  if (ik->is_shared_boot_class()) {
946
    if (class_loader() != nullptr) {
947
      return false;
948
    }
949
  } else if (ik->is_shared_platform_class()) {
950
    if (class_loader() != java_platform_loader()) {
951
      return false;
952
    }
953
  } else if (ik->is_shared_app_class()) {
954
    if (class_loader() != java_system_loader()) {
955
      return false;
956
    }
957
  } else {
958
    // ik was loaded by a custom loader during dump time
959
    if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
960
      return false;
961
    } else {
962
      return true;
963
    }
964
  }
965

966
  // (2) Check if we are loading into the same module from the same location as in dump time.
967

968
  if (CDSConfig::is_using_optimized_module_handling()) {
969
    // Class visibility has not changed between dump time and run time, so a class
970
    // that was visible (and thus archived) during dump time is always visible during runtime.
971
    assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
972
           "visibility cannot change between dump time and runtime");
973
    return true;
974
  }
975
  return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
976
}
977

978
bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
979
                                                    InstanceKlass* ik,
980
                                                    PackageEntry* pkg_entry,
981
                                                    Handle class_loader) {
982
  int scp_index = ik->shared_classpath_index();
983
  assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
984
  assert(scp_index >= 0, "must be");
985
  SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
986
  if (!Universe::is_module_initialized()) {
987
    assert(scp_entry != nullptr, "must be");
988
    // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
989
    // has restricted the classes can be loaded at this step to be only:
990
    // [1] scp_entry->is_modules_image(): classes in java.base, or,
991
    // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
992
    assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
993
           "only these classes can be loaded before the module system is initialized");
994
    assert(class_loader.is_null(), "sanity");
995
    return true;
996
  }
997

998
  if (pkg_entry == nullptr) {
999
    // We might have looked up pkg_entry before the module system was initialized.
1000
    // Need to reload it now.
1001
    TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1002
    if (pkg_name != nullptr) {
1003
      pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1004
    }
1005
  }
1006

1007
  ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1008
  bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1009
  bool was_archived_from_named_module = scp_entry->in_named_module();
1010
  bool visible;
1011

1012
  if (was_archived_from_named_module) {
1013
    if (should_be_in_named_module) {
1014
      // Is the module loaded from the same location as during dump time?
1015
      visible = mod_entry->shared_path_index() == scp_index;
1016
      if (visible) {
1017
        assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1018
      }
1019
    } else {
1020
      // During dump time, this class was in a named module, but at run time, this class should be
1021
      // in an unnamed module.
1022
      visible = false;
1023
    }
1024
  } else {
1025
    if (should_be_in_named_module) {
1026
      // During dump time, this class was in an unnamed, but at run time, this class should be
1027
      // in a named module.
1028
      visible = false;
1029
    } else {
1030
      visible = true;
1031
    }
1032
  }
1033

1034
  return visible;
1035
}
1036

1037
bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1038
                                                     Handle class_loader,  Handle protection_domain,
1039
                                                     bool is_superclass, TRAPS) {
1040
  assert(super_type->is_shared(), "must be");
1041

1042
  // Quick check if the super type has been already loaded.
1043
  // + Don't do it for unregistered classes -- they can be unloaded so
1044
  //   super_type->class_loader_data() could be stale.
1045
  // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1046
  if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1047
    // Check if the superclass is loaded by the current class_loader
1048
    Symbol* name = super_type->name();
1049
    InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1050
    if (check == super_type) {
1051
      return true;
1052
    }
1053
  }
1054

1055
  Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
1056
                                       class_loader, protection_domain, is_superclass, CHECK_0);
1057
  if (found == super_type) {
1058
    return true;
1059
  } else {
1060
    // The dynamically resolved super type is not the same as the one we used during dump time,
1061
    // so we cannot use the class.
1062
    return false;
1063
  }
1064
}
1065

1066
bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1067
                                                      Handle protection_domain, TRAPS) {
1068
  // Check the superclass and interfaces. They must be the same
1069
  // as in dump time, because the layout of <ik> depends on
1070
  // the specific layout of ik->super() and ik->local_interfaces().
1071
  //
1072
  // If unexpected superclass or interfaces are found, we cannot
1073
  // load <ik> from the shared archive.
1074

1075
  if (ik->super() != nullptr &&
1076
      !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1077
                                     class_loader, protection_domain, true, THREAD)) {
1078
    return false;
1079
  }
1080

1081
  Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1082
  int num_interfaces = interfaces->length();
1083
  for (int index = 0; index < num_interfaces; index++) {
1084
    if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1085
      return false;
1086
    }
1087
  }
1088

1089
  return true;
1090
}
1091

1092
InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1093
                                                                Handle class_loader,
1094
                                                                Handle protection_domain,
1095
                                                                PackageEntry* pkg_entry,
1096
                                                                TRAPS) {
1097
  InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1098
  assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1099
  Symbol* cn = shared_nest_host->name();
1100
  Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1101
  if (s != shared_nest_host) {
1102
    // The dynamically resolved nest_host is not the same as the one we used during dump time,
1103
    // so we cannot use ik.
1104
    return nullptr;
1105
  } else {
1106
    assert(s->is_shared(), "must be");
1107
  }
1108

1109
  InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1110

1111
  if (loaded_ik != nullptr) {
1112
    assert(shared_nest_host->is_same_class_package(ik),
1113
           "lambda proxy class and its nest host must be in the same package");
1114
    // The lambda proxy class and its nest host have the same class loader and class loader data,
1115
    // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1116
    assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1117
    assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1118
    ik->set_nest_host(shared_nest_host);
1119
  }
1120

1121
  return loaded_ik;
1122
}
1123

1124
InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1125
                                                   Handle class_loader,
1126
                                                   Handle protection_domain,
1127
                                                   const ClassFileStream *cfs,
1128
                                                   PackageEntry* pkg_entry,
1129
                                                   TRAPS) {
1130
  assert(ik != nullptr, "sanity");
1131
  assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1132
  assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1133
  Symbol* class_name = ik->name();
1134

1135
  if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1136
    return nullptr;
1137
  }
1138

1139
  if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1140
    return nullptr;
1141
  }
1142

1143
  InstanceKlass* new_ik = nullptr;
1144
  // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1145
  // It will be skipped for shared VM hidden lambda proxy classes.
1146
  if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1147
    new_ik = KlassFactory::check_shared_class_file_load_hook(
1148
      ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1149
  }
1150
  if (new_ik != nullptr) {
1151
    // The class is changed by CFLH. Return the new class. The shared class is
1152
    // not used.
1153
    return new_ik;
1154
  }
1155

1156
  // Adjust methods to recover missing data.  They need addresses for
1157
  // interpreter entry points and their default native method address
1158
  // must be reset.
1159

1160
  // Shared classes are all currently loaded by either the bootstrap or
1161
  // internal parallel class loaders, so this will never cause a deadlock
1162
  // on a custom class loader lock.
1163
  // Since this class is already locked with parallel capable class
1164
  // loaders, including the bootstrap loader via the placeholder table,
1165
  // this lock is currently a nop.
1166

1167
  ClassLoaderData* loader_data = class_loader_data(class_loader);
1168
  {
1169
    HandleMark hm(THREAD);
1170
    Handle lockObject = get_loader_lock_or_null(class_loader);
1171
    ObjectLocker ol(lockObject, THREAD);
1172
    // prohibited package check assumes all classes loaded from archive call
1173
    // restore_unshareable_info which calls ik->set_package()
1174
    ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1175
  }
1176

1177
  load_shared_class_misc(ik, loader_data);
1178
  return ik;
1179
}
1180

1181
void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1182
  ik->print_class_load_logging(loader_data, nullptr, nullptr);
1183

1184
  // For boot loader, ensure that GetSystemPackage knows that a class in this
1185
  // package was loaded.
1186
  if (loader_data->is_the_null_class_loader_data()) {
1187
    s2 path_index = ik->shared_classpath_index();
1188
    ik->set_classpath_index(path_index);
1189
  }
1190

1191
  // notify a class loaded from shared object
1192
  ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1193
}
1194

1195
#endif // INCLUDE_CDS
1196

1197
InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1198

1199
  if (class_loader.is_null()) {
1200
    ResourceMark rm(THREAD);
1201
    PackageEntry* pkg_entry = nullptr;
1202
    bool search_only_bootloader_append = false;
1203

1204
    // Find the package in the boot loader's package entry table.
1205
    TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1206
    if (pkg_name != nullptr) {
1207
      pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1208
    }
1209

1210
    // Prior to attempting to load the class, enforce the boot loader's
1211
    // visibility boundaries.
1212
    if (!Universe::is_module_initialized()) {
1213
      // During bootstrapping, prior to module initialization, any
1214
      // class attempting to be loaded must be checked against the
1215
      // java.base packages in the boot loader's PackageEntryTable.
1216
      // No class outside of java.base is allowed to be loaded during
1217
      // this bootstrapping window.
1218
      if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1219
        // Class is either in the unnamed package or in
1220
        // a named package within the unnamed module.  Either
1221
        // case is outside of java.base, do not attempt to
1222
        // load the class post java.base definition.  If
1223
        // java.base has not been defined, let the class load
1224
        // and its package will be checked later by
1225
        // ModuleEntryTable::verify_javabase_packages.
1226
        if (ModuleEntryTable::javabase_defined()) {
1227
          return nullptr;
1228
        }
1229
      } else {
1230
        // Check that the class' package is defined within java.base.
1231
        ModuleEntry* mod_entry = pkg_entry->module();
1232
        Symbol* mod_entry_name = mod_entry->name();
1233
        if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1234
          return nullptr;
1235
        }
1236
      }
1237
    } else {
1238
      // After the module system has been initialized, check if the class'
1239
      // package is in a module defined to the boot loader.
1240
      if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1241
        // Class is either in the unnamed package, in a named package
1242
        // within a module not defined to the boot loader or in a
1243
        // a named package within the unnamed module.  In all cases,
1244
        // limit visibility to search for the class only in the boot
1245
        // loader's append path.
1246
        if (!ClassLoader::has_bootclasspath_append()) {
1247
           // If there is no bootclasspath append entry, no need to continue
1248
           // searching.
1249
           return nullptr;
1250
        }
1251
        search_only_bootloader_append = true;
1252
      }
1253
    }
1254

1255
    // Prior to bootstrapping's module initialization, never load a class outside
1256
    // of the boot loader's module path
1257
    assert(Universe::is_module_initialized() ||
1258
           !search_only_bootloader_append,
1259
           "Attempt to load a class outside of boot loader's module path");
1260

1261
    // Search for classes in the CDS archive.
1262
    InstanceKlass* k = nullptr;
1263

1264
#if INCLUDE_CDS
1265
    if (CDSConfig::is_using_archive())
1266
    {
1267
      PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1268
      InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1269
      if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1270
        SharedClassLoadingMark slm(THREAD, ik);
1271
        k = load_shared_class(ik, class_loader, Handle(), nullptr,  pkg_entry, CHECK_NULL);
1272
      }
1273
    }
1274
#endif
1275

1276
    if (k == nullptr) {
1277
      // Use VM class loader
1278
      PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1279
      k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1280
    }
1281

1282
    // find_or_define_instance_class may return a different InstanceKlass
1283
    if (k != nullptr) {
1284
      CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1285
      k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1286
    }
1287
    return k;
1288
  } else {
1289
    // Use user specified class loader to load class. Call loadClass operation on class_loader.
1290
    ResourceMark rm(THREAD);
1291

1292
    JavaThread* jt = THREAD;
1293

1294
    PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1295
                               ClassLoader::perf_app_classload_selftime(),
1296
                               ClassLoader::perf_app_classload_count(),
1297
                               jt->get_thread_stat()->perf_recursion_counts_addr(),
1298
                               jt->get_thread_stat()->perf_timers_addr(),
1299
                               PerfClassTraceTime::CLASS_LOAD);
1300

1301
    // Translate to external class name format, i.e., convert '/' chars to '.'
1302
    Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1303

1304
    JavaValue result(T_OBJECT);
1305

1306
    InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1307

1308
    // Call public unsynchronized loadClass(String) directly for all class loaders.
1309
    // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1310
    // acquire a class-name based lock rather than the class loader object lock.
1311
    // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1312
    JavaCalls::call_virtual(&result,
1313
                            class_loader,
1314
                            spec_klass,
1315
                            vmSymbols::loadClass_name(),
1316
                            vmSymbols::string_class_signature(),
1317
                            string,
1318
                            CHECK_NULL);
1319

1320
    assert(result.get_type() == T_OBJECT, "just checking");
1321
    oop obj = result.get_oop();
1322

1323
    // Primitive classes return null since forName() can not be
1324
    // used to obtain any of the Class objects representing primitives or void
1325
    if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1326
      InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1327
      // For user defined Java class loaders, check that the name returned is
1328
      // the same as that requested.  This check is done for the bootstrap
1329
      // loader when parsing the class file.
1330
      if (class_name == k->name()) {
1331
        return k;
1332
      }
1333
    }
1334
    // Class is not found or has the wrong name, return null
1335
    return nullptr;
1336
  }
1337
}
1338

1339
InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1340
                                                     Handle class_loader,
1341
                                                     TRAPS) {
1342

1343
  InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1344

1345
  // If everything was OK (no exceptions, no null return value), and
1346
  // class_loader is NOT the defining loader, do a little more bookkeeping.
1347
  if (loaded_class != nullptr &&
1348
      loaded_class->class_loader() != class_loader()) {
1349

1350
    ClassLoaderData* loader_data = class_loader_data(class_loader);
1351
    check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1352

1353
    // Record dependency for non-parent delegation.
1354
    // This recording keeps the defining class loader of the klass (loaded_class) found
1355
    // from being unloaded while the initiating class loader is loaded
1356
    // even if the reference to the defining class loader is dropped
1357
    // before references to the initiating class loader.
1358
    loader_data->record_dependency(loaded_class);
1359

1360
    update_dictionary(THREAD, loaded_class, loader_data);
1361

1362
    if (JvmtiExport::should_post_class_load()) {
1363
      JvmtiExport::post_class_load(THREAD, loaded_class);
1364
    }
1365
  }
1366
  return loaded_class;
1367
}
1368

1369
static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1370
  EventClassDefine event;
1371
  if (event.should_commit()) {
1372
    event.set_definedClass(k);
1373
    event.set_definingClassLoader(def_cld);
1374
    event.commit();
1375
  }
1376
}
1377

1378
void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1379

1380
  ClassLoaderData* loader_data = k->class_loader_data();
1381
  assert(loader_data->class_loader() == class_loader(), "they must be the same");
1382

1383
  // Bootstrap and other parallel classloaders don't acquire a lock,
1384
  // they use placeholder token.
1385
  // If a parallelCapable class loader calls define_instance_class instead of
1386
  // find_or_define_instance_class to get here, we have a timing
1387
  // hole with systemDictionary updates and check_constraints
1388
  if (!is_parallelCapable(class_loader)) {
1389
    assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1390
           get_loader_lock_or_null(class_loader)),
1391
           "define called without lock");
1392
  }
1393

1394
  // Check class-loading constraints. Throw exception if violation is detected.
1395
  // Grabs and releases SystemDictionary_lock
1396
  // The check_constraints/find_class call and update_dictionary sequence
1397
  // must be "atomic" for a specific class/classloader pair so we never
1398
  // define two different instanceKlasses for that class/classloader pair.
1399
  // Existing classloaders will call define_instance_class with the
1400
  // classloader lock held
1401
  // Parallel classloaders will call find_or_define_instance_class
1402
  // which will require a token to perform the define class
1403
  check_constraints(k, loader_data, true, CHECK);
1404

1405
  // Register class just loaded with class loader (placed in ArrayList)
1406
  // Note we do this before updating the dictionary, as this can
1407
  // fail with an OutOfMemoryError (if it does, we will *not* put this
1408
  // class in the dictionary and will not update the class hierarchy).
1409
  // JVMTI FollowReferences needs to find the classes this way.
1410
  if (k->class_loader() != nullptr) {
1411
    methodHandle m(THREAD, Universe::loader_addClass_method());
1412
    JavaValue result(T_VOID);
1413
    JavaCallArguments args(class_loader);
1414
    args.push_oop(Handle(THREAD, k->java_mirror()));
1415
    JavaCalls::call(&result, m, &args, CHECK);
1416
  }
1417

1418
  // Add to class hierarchy, and do possible deoptimizations.
1419
  k->add_to_hierarchy(THREAD);
1420

1421
  // Add to systemDictionary - so other classes can see it.
1422
  // Grabs and releases SystemDictionary_lock
1423
  update_dictionary(THREAD, k, loader_data);
1424

1425
  // notify jvmti
1426
  if (JvmtiExport::should_post_class_load()) {
1427
    JvmtiExport::post_class_load(THREAD, k);
1428
  }
1429
  post_class_define_event(k, loader_data);
1430
}
1431

1432
// Support parallel classloading
1433
// All parallel class loaders, including bootstrap classloader
1434
// lock a placeholder entry for this class/class_loader pair
1435
// to allow parallel defines of different classes for this class loader
1436
// With AllowParallelDefine flag==true, in case they do not synchronize around
1437
// FindLoadedClass/DefineClass, calls, we check for parallel
1438
// loading for them, wait if a defineClass is in progress
1439
// and return the initial requestor's results
1440
// This flag does not apply to the bootstrap classloader.
1441
// With AllowParallelDefine flag==false, call through to define_instance_class
1442
// which will throw LinkageError: duplicate class definition.
1443
// False is the requested default.
1444
// For better performance, the class loaders should synchronize
1445
// findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1446
// potentially waste time reading and parsing the bytestream.
1447
// Note: VM callers should ensure consistency of k/class_name,class_loader
1448
// Be careful when modifying this code: once you have run
1449
// PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1450
// you need to find_and_remove it before returning.
1451
// So be careful to not exit with a CHECK_ macro between these calls.
1452
InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1453
                                                       InstanceKlass* k, TRAPS) {
1454

1455
  Symbol* name_h = k->name();
1456
  ClassLoaderData* loader_data = class_loader_data(class_loader);
1457
  Dictionary* dictionary = loader_data->dictionary();
1458

1459
  // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1460
  {
1461
    MutexLocker mu(THREAD, SystemDictionary_lock);
1462
    // First check if class already defined
1463
    if (is_parallelDefine(class_loader)) {
1464
      InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1465
      if (check != nullptr) {
1466
        return check;
1467
      }
1468
    }
1469

1470
    // Acquire define token for this class/classloader
1471
    PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1472
                                                             PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1473
    // Wait if another thread defining in parallel
1474
    // All threads wait - even those that will throw duplicate class: otherwise
1475
    // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1476
    // if other thread has not finished updating dictionary
1477
    while (probe->definer() != nullptr) {
1478
      SystemDictionary_lock->wait();
1479
    }
1480
    // Only special cases allow parallel defines and can use other thread's results
1481
    // Other cases fall through, and may run into duplicate defines
1482
    // caught by finding an entry in the SystemDictionary
1483
    if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1484
      InstanceKlass* ik = probe->instance_klass();
1485
      PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1486
      SystemDictionary_lock->notify_all();
1487
#ifdef ASSERT
1488
      InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1489
      assert(check != nullptr, "definer missed recording success");
1490
#endif
1491
      return ik;
1492
    } else {
1493
      // This thread will define the class (even if earlier thread tried and had an error)
1494
      probe->set_definer(THREAD);
1495
    }
1496
  }
1497

1498
  define_instance_class(k, class_loader, THREAD);
1499

1500
  // definer must notify any waiting threads
1501
  {
1502
    MutexLocker mu(THREAD, SystemDictionary_lock);
1503
    PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1504
    assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1505
    if (!HAS_PENDING_EXCEPTION) {
1506
      probe->set_instance_klass(k);
1507
    }
1508
    probe->set_definer(nullptr);
1509
    PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1510
    SystemDictionary_lock->notify_all();
1511
  }
1512

1513
  return HAS_PENDING_EXCEPTION ? nullptr : k;
1514
}
1515

1516
// If a class loader supports parallel classloading handle parallel define requests.
1517
// find_or_define_instance_class may return a different InstanceKlass
1518
InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1519
                                                               InstanceKlass* k, TRAPS) {
1520
  InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1521
  // Clean up original InstanceKlass if duplicate or error
1522
  if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1523
    // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1524
    assert(defined_k != nullptr, "Should have a klass if there's no exception");
1525
    k->class_loader_data()->add_to_deallocate_list(k);
1526
  } else if (HAS_PENDING_EXCEPTION) {
1527
    // Remove this InstanceKlass from the LoaderConstraintTable if added.
1528
    LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1529
    assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1530
    k->class_loader_data()->add_to_deallocate_list(k);
1531
  }
1532
  return defined_k;
1533
}
1534

1535

1536
// ----------------------------------------------------------------------------
1537
// GC support
1538

1539
// Assumes classes in the SystemDictionary are only unloaded at a safepoint
1540
bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1541

1542
  bool unloading_occurred;
1543
  bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1544
  {
1545
    GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1546
    assert_locked_or_safepoint(ClassLoaderDataGraph_lock);  // caller locks.
1547
    // First, mark for unload all ClassLoaderData referencing a dead class loader.
1548
    unloading_occurred = ClassLoaderDataGraph::do_unloading();
1549
    if (unloading_occurred) {
1550
      ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1551
      JFR_ONLY(Jfr::on_unloading_classes();)
1552
      MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1553
      ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1554
      ClassLoaderDataGraph::clean_module_and_package_info();
1555
      LoaderConstraintTable::purge_loader_constraints();
1556
      ResolutionErrorTable::purge_resolution_errors();
1557
    }
1558
  }
1559

1560
  GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1561

1562
  if (unloading_occurred) {
1563
    SymbolTable::trigger_cleanup();
1564

1565
    if (java_lang_System::allow_security_manager()) {
1566
      // Oops referenced by the protection domain cache table may get unreachable independently
1567
      // of the class loader (eg. cached protection domain oops). So we need to
1568
      // explicitly unlink them here.
1569
      // All protection domain oops are linked to the caller class, so if nothing
1570
      // unloads, this is not needed.
1571
      ProtectionDomainCacheTable::trigger_cleanup();
1572
    } else {
1573
      assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1574
    }
1575

1576
    ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1577
    InstanceKlass::clean_initialization_error_table();
1578
  }
1579

1580
  return unloading_occurred;
1581
}
1582

1583
void SystemDictionary::methods_do(void f(Method*)) {
1584
  // Walk methods in loaded classes
1585

1586
  {
1587
    MutexLocker ml(ClassLoaderDataGraph_lock);
1588
    ClassLoaderDataGraph::methods_do(f);
1589
  }
1590

1591
  auto doit = [&] (InvokeMethodKey key, Method* method) {
1592
    if (method != nullptr) {
1593
      f(method);
1594
    }
1595
  };
1596

1597
  {
1598
    MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1599
    _invoke_method_intrinsic_table->iterate_all(doit);
1600
  }
1601

1602
}
1603

1604
// ----------------------------------------------------------------------------
1605
// Initialization
1606

1607
void SystemDictionary::initialize(TRAPS) {
1608
  _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1609
  _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1610
  ResolutionErrorTable::initialize();
1611
  LoaderConstraintTable::initialize();
1612
  PlaceholderTable::initialize();
1613
  ProtectionDomainCacheTable::initialize();
1614
#if INCLUDE_CDS
1615
  SystemDictionaryShared::initialize();
1616
#endif
1617
  // Resolve basic classes
1618
  vmClasses::resolve_all(CHECK);
1619
  // Resolve classes used by archived heap objects
1620
  if (CDSConfig::is_using_archive()) {
1621
    HeapShared::resolve_classes(THREAD);
1622
  }
1623
}
1624

1625
// Constraints on class loaders. The details of the algorithm can be
1626
// found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1627
// Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
1628
// that the dictionary needs to maintain a set of constraints that
1629
// must be satisfied by all classes in the dictionary.
1630
// if defining is true, then LinkageError if already in dictionary
1631
// if initiating loader, then ok if InstanceKlass matches existing entry
1632

1633
void SystemDictionary::check_constraints(InstanceKlass* k,
1634
                                         ClassLoaderData* loader_data,
1635
                                         bool defining,
1636
                                         TRAPS) {
1637
  ResourceMark rm(THREAD);
1638
  stringStream ss;
1639
  bool throwException = false;
1640

1641
  {
1642
    Symbol* name = k->name();
1643

1644
    MutexLocker mu(THREAD, SystemDictionary_lock);
1645

1646
    InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1647
    if (check != nullptr) {
1648
      // If different InstanceKlass - duplicate class definition,
1649
      // else - ok, class loaded by a different thread in parallel.
1650
      // We should only have found it if it was done loading and ok to use.
1651

1652
      if ((defining == true) || (k != check)) {
1653
        throwException = true;
1654
        ss.print("loader %s", loader_data->loader_name_and_id());
1655
        ss.print(" attempted duplicate %s definition for %s. (%s)",
1656
                 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1657
      } else {
1658
        return;
1659
      }
1660
    }
1661

1662
    if (throwException == false) {
1663
      if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1664
        throwException = true;
1665
        ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1666
        ss.print(" wants to load %s %s.",
1667
                 k->external_kind(), k->external_name());
1668
        Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1669
        if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1670
          ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1671
                   existing_klass->external_kind(),
1672
                   existing_klass->class_loader_data()->loader_name_and_id(),
1673
                   existing_klass->class_in_module_of_loader(false, true));
1674
        } else {
1675
          ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1676
        }
1677
      }
1678
    }
1679
  }
1680

1681
  // Throw error now if needed (cannot throw while holding
1682
  // SystemDictionary_lock because of rank ordering)
1683
  if (throwException == true) {
1684
    THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1685
  }
1686
}
1687

1688
// Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1689
// have been called.
1690
void SystemDictionary::update_dictionary(JavaThread* current,
1691
                                         InstanceKlass* k,
1692
                                         ClassLoaderData* loader_data) {
1693
  MonitorLocker mu1(SystemDictionary_lock);
1694

1695
  // Make a new dictionary entry.
1696
  Symbol* name  = k->name();
1697
  Dictionary* dictionary = loader_data->dictionary();
1698
  InstanceKlass* sd_check = dictionary->find_class(current, name);
1699
  if (sd_check == nullptr) {
1700
    dictionary->add_klass(current, name, k);
1701
  }
1702
  mu1.notify_all();
1703
}
1704

1705

1706
// Try to find a class name using the loader constraints.  The
1707
// loader constraints might know about a class that isn't fully loaded
1708
// yet and these will be ignored.
1709
Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1710
                    Thread* current, Symbol* class_name, Handle class_loader) {
1711

1712
  // First see if it has been loaded directly.
1713
  // Force the protection domain to be null.  (This removes protection checks.)
1714
  Handle no_protection_domain;
1715
  Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1716
                                              no_protection_domain);
1717
  if (klass != nullptr)
1718
    return klass;
1719

1720
  // Now look to see if it has been loaded elsewhere, and is subject to
1721
  // a loader constraint that would require this loader to return the
1722
  // klass that is already loaded.
1723
  if (Signature::is_array(class_name)) {
1724
    // For array classes, their Klass*s are not kept in the
1725
    // constraint table. The element Klass*s are.
1726
    SignatureStream ss(class_name, false);
1727
    int ndims = ss.skip_array_prefix();  // skip all '['s
1728
    BasicType t = ss.type();
1729
    if (t != T_OBJECT) {
1730
      klass = Universe::typeArrayKlass(t);
1731
    } else {
1732
      MutexLocker mu(current, SystemDictionary_lock);
1733
      klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1734
    }
1735
    // If element class already loaded, allocate array klass
1736
    if (klass != nullptr) {
1737
      klass = klass->array_klass_or_null(ndims);
1738
    }
1739
  } else {
1740
    MutexLocker mu(current, SystemDictionary_lock);
1741
    // Non-array classes are easy: simply check the constraint table.
1742
    klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1743
  }
1744

1745
  return klass;
1746
}
1747

1748
bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1749
                                             Klass* klass_being_linked,
1750
                                             Handle class_loader1,
1751
                                             Handle class_loader2) {
1752
  ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1753
  ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1754

1755
  Symbol* constraint_name = nullptr;
1756

1757
  if (!Signature::is_array(class_name)) {
1758
    constraint_name = class_name;
1759
  } else {
1760
    // For array classes, their Klass*s are not kept in the
1761
    // constraint table. The element classes are.
1762
    SignatureStream ss(class_name, false);
1763
    ss.skip_array_prefix();  // skip all '['s
1764
    if (!ss.has_envelope()) {
1765
      return true;     // primitive types always pass
1766
    }
1767
    constraint_name = ss.as_symbol();
1768
    // Increment refcount to keep constraint_name alive after
1769
    // SignatureStream is destructed. It will be decremented below
1770
    // before returning.
1771
    constraint_name->increment_refcount();
1772
  }
1773

1774
  Dictionary* dictionary1 = loader_data1->dictionary();
1775
  Dictionary* dictionary2 = loader_data2->dictionary();
1776

1777
  JavaThread* current = JavaThread::current();
1778
  {
1779
    MutexLocker mu_s(SystemDictionary_lock);
1780
    InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1781
    InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1782
    bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1783
                                                   klass2, loader_data2);
1784
#if INCLUDE_CDS
1785
    if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1786
        !klass_being_linked->is_shared()) {
1787
         SystemDictionaryShared::record_linking_constraint(constraint_name,
1788
                                     InstanceKlass::cast(klass_being_linked),
1789
                                     class_loader1, class_loader2);
1790
    }
1791
#endif // INCLUDE_CDS
1792
    if (Signature::is_array(class_name)) {
1793
      constraint_name->decrement_refcount();
1794
    }
1795
    return result;
1796
  }
1797
}
1798

1799
// Add entry to resolution error table to record the error when the first
1800
// attempt to resolve a reference to a class has failed.
1801
void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1802
                                            Symbol* error, const char* message,
1803
                                            Symbol* cause, const char* cause_msg) {
1804
  {
1805
    MutexLocker ml(Thread::current(), SystemDictionary_lock);
1806
    ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1807
    if (entry == nullptr) {
1808
      ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1809
    }
1810
  }
1811
}
1812

1813
// Delete a resolution error for RedefineClasses for a constant pool is going away
1814
void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1815
  ResolutionErrorTable::delete_entry(pool);
1816
}
1817

1818
// Lookup resolution error table. Returns error if found, otherwise null.
1819
Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1820
                                                const char** message,
1821
                                                Symbol** cause, const char** cause_msg) {
1822

1823
  {
1824
    MutexLocker ml(Thread::current(), SystemDictionary_lock);
1825
    ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1826
    if (entry != nullptr) {
1827
      *message = entry->message();
1828
      *cause = entry->cause();
1829
      *cause_msg = entry->cause_msg();
1830
      return entry->error();
1831
    } else {
1832
      return nullptr;
1833
    }
1834
  }
1835
}
1836

1837
// Add an entry to resolution error table to record an error in resolving or
1838
// validating a nest host. This is used to construct informative error
1839
// messages when IllegalAccessError's occur. If an entry already exists it will
1840
// be updated with the nest host error message.
1841

1842
void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1843
                                           int which,
1844
                                           const char* message) {
1845
  {
1846
    MutexLocker ml(Thread::current(), SystemDictionary_lock);
1847
    ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1848
    if (entry != nullptr && entry->nest_host_error() == nullptr) {
1849
      // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1850
      // still want to add the error message for the higher-level access checks to report. We should
1851
      // only reach here under the same error condition, so we can ignore the potential race with setting
1852
      // the message. If we see it is already set then we can ignore it.
1853
      entry->set_nest_host_error(message);
1854
    } else {
1855
      ResolutionErrorTable::add_entry(pool, which, message);
1856
    }
1857
  }
1858
}
1859

1860
// Lookup any nest host error
1861
const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1862
  {
1863
    MutexLocker ml(Thread::current(), SystemDictionary_lock);
1864
    ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1865
    if (entry != nullptr) {
1866
      return entry->nest_host_error();
1867
    } else {
1868
      return nullptr;
1869
    }
1870
  }
1871
}
1872

1873
// Signature constraints ensure that callers and callees agree about
1874
// the meaning of type names in their signatures.  This routine is the
1875
// intake for constraints.  It collects them from several places:
1876
//
1877
//  * LinkResolver::resolve_method (if check_access is true) requires
1878
//    that the resolving class (the caller) and the defining class of
1879
//    the resolved method (the callee) agree on each type in the
1880
//    method's signature.
1881
//
1882
//  * LinkResolver::resolve_interface_method performs exactly the same
1883
//    checks.
1884
//
1885
//  * LinkResolver::resolve_field requires that the constant pool
1886
//    attempting to link to a field agree with the field's defining
1887
//    class about the type of the field signature.
1888
//
1889
//  * klassVtable::initialize_vtable requires that, when a class
1890
//    overrides a vtable entry allocated by a superclass, that the
1891
//    overriding method (i.e., the callee) agree with the superclass
1892
//    on each type in the method's signature.
1893
//
1894
//  * klassItable::initialize_itable requires that, when a class fills
1895
//    in its itables, for each non-abstract method installed in an
1896
//    itable, the method (i.e., the callee) agree with the interface
1897
//    on each type in the method's signature.
1898
//
1899
// All those methods have a boolean (check_access, checkconstraints)
1900
// which turns off the checks.  This is used from specialized contexts
1901
// such as bootstrapping, dumping, and debugging.
1902
//
1903
// No direct constraint is placed between the class and its
1904
// supertypes.  Constraints are only placed along linked relations
1905
// between callers and callees.  When a method overrides or implements
1906
// an abstract method in a supertype (superclass or interface), the
1907
// constraints are placed as if the supertype were the caller to the
1908
// overriding method.  (This works well, since callers to the
1909
// supertype have already established agreement between themselves and
1910
// the supertype.)  As a result of all this, a class can disagree with
1911
// its supertype about the meaning of a type name, as long as that
1912
// class neither calls a relevant method of the supertype, nor is
1913
// called (perhaps via an override) from the supertype.
1914
//
1915
//
1916
// SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1917
//
1918
// Make sure all class components (including arrays) in the given
1919
// signature will be resolved to the same class in both loaders.
1920
// Returns the name of the type that failed a loader constraint check, or
1921
// null if no constraint failed.  No exception except OOME is thrown.
1922
// Arrays are not added to the loader constraint table, their elements are.
1923
Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1924
                                                  Klass* klass_being_linked,
1925
                                                  Handle loader1, Handle loader2,
1926
                                                  bool is_method)  {
1927
  // Nothing to do if loaders are the same.
1928
  if (loader1() == loader2()) {
1929
    return nullptr;
1930
  }
1931

1932
  for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1933
    if (ss.is_reference()) {
1934
      Symbol* sig = ss.as_symbol();
1935
      // Note: In the future, if template-like types can take
1936
      // arguments, we will want to recognize them and dig out class
1937
      // names hiding inside the argument lists.
1938
      if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1939
        return sig;
1940
      }
1941
    }
1942
  }
1943
  return nullptr;
1944
}
1945

1946
Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1947
                                                       Symbol* signature,
1948
                                                       TRAPS) {
1949

1950
  const int iid_as_int = vmIntrinsics::as_int(iid);
1951
  assert(MethodHandles::is_signature_polymorphic(iid) &&
1952
         MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1953
         iid != vmIntrinsics::_invokeGeneric,
1954
         "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1955

1956
  InvokeMethodKey key(signature, iid_as_int);
1957
  Method** met = nullptr;
1958

1959
  // We only want one entry in the table for this (signature/id, method) pair but the code
1960
  // to create the intrinsic method needs to be outside the lock.
1961
  // The first thread claims the entry by adding the key and the other threads wait, until the
1962
  // Method has been added as the value.
1963
  {
1964
    MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1965
    while (true) {
1966
      bool created;
1967
      met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
1968
      assert(met != nullptr, "either created or found");
1969
      if (*met != nullptr) {
1970
        return *met;
1971
      } else if (created) {
1972
        // The current thread won the race and will try to create the full entry.
1973
        break;
1974
      } else {
1975
        // Another thread beat us to it, so wait for them to complete
1976
        // and return *met; or if they hit an error we get another try.
1977
        ml.wait();
1978
        // Note it is not safe to read *met here as that entry could have
1979
        // been deleted, so we must loop and try put_if_absent again.
1980
      }
1981
    }
1982
  }
1983

1984
  methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
1985
  bool throw_error = HAS_PENDING_EXCEPTION;
1986
  if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
1987
    // Generate a compiled form of the MH intrinsic
1988
    // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
1989
    AdapterHandlerLibrary::create_native_wrapper(m);
1990
    // Check if have the compiled code.
1991
    throw_error = (!m->has_compiled_code());
1992
  }
1993

1994
  {
1995
    MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1996
    if (throw_error) {
1997
      // Remove the entry and let another thread try, or get the same exception.
1998
      bool removed = _invoke_method_intrinsic_table->remove(key);
1999
      assert(removed, "must be the owner");
2000
      ml.notify_all();
2001
    } else {
2002
      signature->make_permanent(); // The signature is never unloaded.
2003
      assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2004
             m->code()->entry_point() == m->from_compiled_entry()),
2005
             "MH intrinsic invariant");
2006
      *met = m(); // insert the element
2007
      ml.notify_all();
2008
      return m();
2009
    }
2010
  }
2011

2012
  // Throw OOM or the pending exception in the JavaThread
2013
  if (throw_error && !HAS_PENDING_EXCEPTION) {
2014
    THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2015
                   "Out of space in CodeCache for method handle intrinsic");
2016
  }
2017
  return nullptr;
2018
}
2019

2020
// Helper for unpacking the return value from linkMethod and linkCallSite.
2021
static Method* unpack_method_and_appendix(Handle mname,
2022
                                          Klass* accessing_klass,
2023
                                          objArrayHandle appendix_box,
2024
                                          Handle* appendix_result,
2025
                                          TRAPS) {
2026
  if (mname.not_null()) {
2027
    Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2028
    if (m != nullptr) {
2029
      oop appendix = appendix_box->obj_at(0);
2030
      LogTarget(Info, methodhandles) lt;
2031
      if (lt.develop_is_enabled()) {
2032
        ResourceMark rm(THREAD);
2033
        LogStream ls(lt);
2034
        ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2035
        m->print_on(&ls);
2036
        if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2037
        ls.cr();
2038
      }
2039

2040
      (*appendix_result) = Handle(THREAD, appendix);
2041
      // the target is stored in the cpCache and if a reference to this
2042
      // MemberName is dropped we need a way to make sure the
2043
      // class_loader containing this method is kept alive.
2044
      methodHandle mh(THREAD, m); // record_dependency can safepoint.
2045
      ClassLoaderData* this_key = accessing_klass->class_loader_data();
2046
      this_key->record_dependency(m->method_holder());
2047
      return mh();
2048
    }
2049
  }
2050
  THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2051
}
2052

2053
Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2054
                                                     Symbol* name,
2055
                                                     Symbol* signature,
2056
                                                     Klass* accessing_klass,
2057
                                                     Handle* appendix_result,
2058
                                                     TRAPS) {
2059
  guarantee(THREAD->can_call_java(), "");
2060
  Handle method_type =
2061
    SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2062

2063
  int ref_kind = JVM_REF_invokeVirtual;
2064
  oop name_oop = StringTable::intern(name, CHECK_NULL);
2065
  Handle name_str (THREAD, name_oop);
2066
  objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2067
  assert(appendix_box->obj_at(0) == nullptr, "");
2068

2069
  // This should not happen.  JDK code should take care of that.
2070
  if (accessing_klass == nullptr || method_type.is_null()) {
2071
    THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2072
  }
2073

2074
  // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2075
  JavaCallArguments args;
2076
  args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2077
  args.push_int(ref_kind);
2078
  args.push_oop(Handle(THREAD, klass->java_mirror()));
2079
  args.push_oop(name_str);
2080
  args.push_oop(method_type);
2081
  args.push_oop(appendix_box);
2082
  JavaValue result(T_OBJECT);
2083
  JavaCalls::call_static(&result,
2084
                         vmClasses::MethodHandleNatives_klass(),
2085
                         vmSymbols::linkMethod_name(),
2086
                         vmSymbols::linkMethod_signature(),
2087
                         &args, CHECK_NULL);
2088
  Handle mname(THREAD, result.get_oop());
2089
  return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2090
}
2091

2092
// Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2093
// We must ensure that all class loaders everywhere will reach this class, for any client.
2094
// This is a safe bet for public classes in java.lang, such as Object and String.
2095
// We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2096
// Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2097
static bool is_always_visible_class(oop mirror) {
2098
  Klass* klass = java_lang_Class::as_Klass(mirror);
2099
  if (klass->is_objArray_klass()) {
2100
    klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2101
  }
2102
  if (klass->is_typeArray_klass()) {
2103
    return true; // primitive array
2104
  }
2105
  assert(klass->is_instance_klass(), "%s", klass->external_name());
2106
  return klass->is_public() &&
2107
         (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) ||       // java.lang
2108
          InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass()));  // java.lang.invoke
2109
}
2110

2111
// Find or construct the Java mirror (java.lang.Class instance) for
2112
// the given field type signature, as interpreted relative to the
2113
// given class loader.  Handles primitives, void, references, arrays,
2114
// and all other reflectable types, except method types.
2115
// N.B.  Code in reflection should use this entry point.
2116
Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2117
                                                   Klass* accessing_klass,
2118
                                                   Handle class_loader,
2119
                                                   Handle protection_domain,
2120
                                                   SignatureStream::FailureMode failure_mode,
2121
                                                   TRAPS) {
2122
  assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2123
         "one or the other, or perhaps neither");
2124

2125
  // What we have here must be a valid field descriptor,
2126
  // and all valid field descriptors are supported.
2127
  // Produce the same java.lang.Class that reflection reports.
2128
  if (accessing_klass != nullptr) {
2129
    class_loader      = Handle(THREAD, accessing_klass->class_loader());
2130
    protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2131
  }
2132
  ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2133
  oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2134
  if (mirror_oop == nullptr) {
2135
    return Handle();  // report failure this way
2136
  }
2137
  Handle mirror(THREAD, mirror_oop);
2138

2139
  if (accessing_klass != nullptr) {
2140
    // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2141
    Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2142
    if (sel_klass != nullptr) {
2143
      LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2144
    }
2145
  }
2146
  return mirror;
2147
}
2148

2149

2150
// Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2151
// signature, as interpreted relative to the given class loader.
2152
// Because of class loader constraints, all method handle usage must be
2153
// consistent with this loader.
2154
Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2155
                                                 Klass* accessing_klass,
2156
                                                 TRAPS) {
2157
  Handle empty;
2158
  OopHandle* o;
2159
  {
2160
    MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2161
    o = _invoke_method_type_table->get(signature);
2162
  }
2163

2164
  if (o != nullptr) {
2165
    oop mt = o->resolve();
2166
    assert(java_lang_invoke_MethodType::is_instance(mt), "");
2167
    return Handle(THREAD, mt);
2168
  } else if (!THREAD->can_call_java()) {
2169
    warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2170
    return Handle();  // do not attempt from within compiler, unless it was cached
2171
  }
2172

2173
  Handle class_loader, protection_domain;
2174
  if (accessing_klass != nullptr) {
2175
    class_loader      = Handle(THREAD, accessing_klass->class_loader());
2176
    protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2177
  }
2178
  bool can_be_cached = true;
2179
  int npts = ArgumentCount(signature).size();
2180
  objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2181
  int arg = 0;
2182
  Handle rt; // the return type from the signature
2183
  ResourceMark rm(THREAD);
2184
  for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2185
    oop mirror = nullptr;
2186
    if (can_be_cached) {
2187
      // Use neutral class loader to lookup candidate classes to be placed in the cache.
2188
      mirror = ss.as_java_mirror(Handle(), Handle(),
2189
                                 SignatureStream::ReturnNull, CHECK_(empty));
2190
      if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2191
        // Fall back to accessing_klass context.
2192
        can_be_cached = false;
2193
      }
2194
    }
2195
    if (!can_be_cached) {
2196
      // Resolve, throwing a real error if it doesn't work.
2197
      mirror = ss.as_java_mirror(class_loader, protection_domain,
2198
                                 SignatureStream::NCDFError, CHECK_(empty));
2199
    }
2200
    assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2201
    if (ss.at_return_type())
2202
      rt = Handle(THREAD, mirror);
2203
    else
2204
      pts->obj_at_put(arg++, mirror);
2205

2206
    // Check accessibility.
2207
    if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2208
      Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2209
      mirror = nullptr;  // safety
2210
      // Emulate ConstantPool::verify_constant_pool_resolve.
2211
      LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2212
    }
2213
  }
2214
  assert(arg == npts, "");
2215

2216
  // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2217
  JavaCallArguments args(Handle(THREAD, rt()));
2218
  args.push_oop(pts);
2219
  JavaValue result(T_OBJECT);
2220
  JavaCalls::call_static(&result,
2221
                         vmClasses::MethodHandleNatives_klass(),
2222
                         vmSymbols::findMethodHandleType_name(),
2223
                         vmSymbols::findMethodHandleType_signature(),
2224
                         &args, CHECK_(empty));
2225
  Handle method_type(THREAD, result.get_oop());
2226

2227
  if (can_be_cached) {
2228
    // We can cache this MethodType inside the JVM.
2229
    MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2230
    bool created = false;
2231
    assert(method_type != nullptr, "unexpected null");
2232
    OopHandle* h = _invoke_method_type_table->get(signature);
2233
    if (h == nullptr) {
2234
      signature->make_permanent(); // The signature is never unloaded.
2235
      OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2236
      bool created = _invoke_method_type_table->put(signature, elem);
2237
      assert(created, "better be created");
2238
    }
2239
  }
2240
  // report back to the caller with the MethodType
2241
  return method_type;
2242
}
2243

2244
Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2245
                                                Klass* accessing_klass,
2246
                                                TRAPS) {
2247
  Handle empty;
2248
  ResourceMark rm(THREAD);
2249
  SignatureStream ss(signature, /*is_method=*/ false);
2250
  if (!ss.is_done()) {
2251
    Handle class_loader, protection_domain;
2252
    if (accessing_klass != nullptr) {
2253
      class_loader      = Handle(THREAD, accessing_klass->class_loader());
2254
      protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2255
    }
2256
    oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2257
    ss.next();
2258
    if (ss.is_done()) {
2259
      return Handle(THREAD, mirror);
2260
    }
2261
  }
2262
  return empty;
2263
}
2264

2265
// Ask Java code to find or construct a method handle constant.
2266
Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2267
                                                     int ref_kind, //e.g., JVM_REF_invokeVirtual
2268
                                                     Klass* callee,
2269
                                                     Symbol* name,
2270
                                                     Symbol* signature,
2271
                                                     TRAPS) {
2272
  Handle empty;
2273
  if (caller == nullptr) {
2274
    THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2275
  }
2276
  Handle name_str      = java_lang_String::create_from_symbol(name,      CHECK_(empty));
2277
  Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2278

2279
  // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2280
  Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2281
  java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2282
  java_lang_invoke_MemberName::set_name (mname(), name_str());
2283
  java_lang_invoke_MemberName::set_type (mname(), signature_str());
2284
  java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2285

2286
  if (ref_kind == JVM_REF_invokeVirtual &&
2287
      MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2288
    // Skip resolution for public signature polymorphic methods such as
2289
    // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2290
    // They require appendix argument which MemberName resolution doesn't handle.
2291
    // There's special logic on JDK side to handle them
2292
    // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2293
  } else {
2294
    MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2295
  }
2296

2297
  // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2298
  Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2299

2300
  // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2301
  JavaCallArguments args;
2302
  args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2303
  args.push_int(ref_kind);
2304
  args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2305
  args.push_oop(name_str);
2306
  args.push_oop(type);
2307
  JavaValue result(T_OBJECT);
2308
  JavaCalls::call_static(&result,
2309
                         vmClasses::MethodHandleNatives_klass(),
2310
                         vmSymbols::linkMethodHandleConstant_name(),
2311
                         vmSymbols::linkMethodHandleConstant_signature(),
2312
                         &args, CHECK_(empty));
2313
  return Handle(THREAD, result.get_oop());
2314
}
2315

2316
// Ask Java to run a bootstrap method, in order to create a dynamic call site
2317
// while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2318
// with linkage results being stored back into the bootstrap specifier.
2319
void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2320
  // Resolve the bootstrap specifier, its name, type, and static arguments
2321
  bootstrap_specifier.resolve_bsm(CHECK);
2322

2323
  // This should not happen.  JDK code should take care of that.
2324
  if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2325
    THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2326
  }
2327

2328
  bool is_indy = bootstrap_specifier.is_method_call();
2329
  objArrayHandle appendix_box;
2330
  if (is_indy) {
2331
    // Some method calls may require an appendix argument.  Arrange to receive it.
2332
    appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2333
    assert(appendix_box->obj_at(0) == nullptr, "");
2334
  }
2335

2336
  // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2337
  //       indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2338
  JavaCallArguments args;
2339
  args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2340
  args.push_oop(bootstrap_specifier.bsm());
2341
  args.push_oop(bootstrap_specifier.name_arg());
2342
  args.push_oop(bootstrap_specifier.type_arg());
2343
  args.push_oop(bootstrap_specifier.arg_values());
2344
  if (is_indy) {
2345
    args.push_oop(appendix_box);
2346
  }
2347
  JavaValue result(T_OBJECT);
2348
  JavaCalls::call_static(&result,
2349
                         vmClasses::MethodHandleNatives_klass(),
2350
                         is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2351
                         is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2352
                         &args, CHECK);
2353

2354
  Handle value(THREAD, result.get_oop());
2355
  if (is_indy) {
2356
    Handle appendix;
2357
    Method* method = unpack_method_and_appendix(value,
2358
                                                bootstrap_specifier.caller(),
2359
                                                appendix_box,
2360
                                                &appendix, CHECK);
2361
    methodHandle mh(THREAD, method);
2362
    bootstrap_specifier.set_resolved_method(mh, appendix);
2363
  } else {
2364
    bootstrap_specifier.set_resolved_value(value);
2365
  }
2366

2367
  // sanity check
2368
  assert(bootstrap_specifier.is_resolved() ||
2369
         (bootstrap_specifier.is_method_call() &&
2370
          bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2371
}
2372

2373

2374
bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2375
  assert(m != nullptr, "Unexpected nullptr Method*");
2376
  return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2377
}
2378

2379
// ----------------------------------------------------------------------------
2380

2381
void SystemDictionary::print_on(outputStream *st) {
2382
  CDS_ONLY(SystemDictionaryShared::print_on(st));
2383
  GCMutexLocker mu(SystemDictionary_lock);
2384

2385
  ClassLoaderDataGraph::print_dictionary(st);
2386

2387
  // Placeholders
2388
  PlaceholderTable::print_on(st);
2389
  st->cr();
2390

2391
  // loader constraints - print under SD_lock
2392
  LoaderConstraintTable::print_on(st);
2393
  st->cr();
2394

2395
  ProtectionDomainCacheTable::print_on(st);
2396
  st->cr();
2397
}
2398

2399
void SystemDictionary::print() { print_on(tty); }
2400

2401
void SystemDictionary::verify() {
2402

2403
  GCMutexLocker mu(SystemDictionary_lock);
2404

2405
  // Verify dictionary
2406
  ClassLoaderDataGraph::verify_dictionary();
2407

2408
  // Verify constraint table
2409
  LoaderConstraintTable::verify();
2410

2411
  // Verify protection domain table
2412
  ProtectionDomainCacheTable::verify();
2413
}
2414

2415
void SystemDictionary::dump(outputStream *st, bool verbose) {
2416
  assert_locked_or_safepoint(SystemDictionary_lock);
2417
  if (verbose) {
2418
    print_on(st);
2419
  } else {
2420
    CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2421
    ClassLoaderDataGraph::print_table_statistics(st);
2422
    LoaderConstraintTable::print_table_statistics(st);
2423
    ProtectionDomainCacheTable::print_table_statistics(st);
2424
  }
2425
}
2426

2427
// Utility for dumping dictionaries.
2428
SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2429
                                 DCmdWithParser(output, heap),
2430
  _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2431
           "BOOLEAN", false, "false") {
2432
  _dcmdparser.add_dcmd_option(&_verbose);
2433
}
2434

2435
void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2436
  VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2437
                         _verbose.value());
2438
  VMThread::execute(&dumper);
2439
}
2440

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