1 /*
   2  * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "cds/aotClassInitializer.hpp"
  26 #include "cds/aotMetaspace.hpp"
  27 #include "cds/archiveUtils.hpp"
  28 #include "cds/cdsConfig.hpp"
  29 #include "cds/cdsEnumKlass.hpp"
  30 #include "cds/classListWriter.hpp"
  31 #include "cds/heapShared.hpp"
  32 #include "classfile/classFileParser.hpp"
  33 #include "classfile/classFileStream.hpp"
  34 #include "classfile/classLoader.hpp"
  35 #include "classfile/classLoaderData.inline.hpp"
  36 #include "classfile/javaClasses.hpp"
  37 #include "classfile/moduleEntry.hpp"
  38 #include "classfile/systemDictionary.hpp"
  39 #include "classfile/systemDictionaryShared.hpp"
  40 #include "classfile/verifier.hpp"
  41 #include "classfile/vmClasses.hpp"
  42 #include "classfile/vmSymbols.hpp"
  43 #include "code/codeCache.hpp"
  44 #include "code/dependencyContext.hpp"
  45 #include "compiler/compilationPolicy.hpp"
  46 #include "compiler/compileBroker.hpp"
  47 #include "gc/shared/collectedHeap.inline.hpp"
  48 #include "interpreter/bytecodeStream.hpp"
  49 #include "interpreter/oopMapCache.hpp"
  50 #include "interpreter/rewriter.hpp"
  51 #include "jvm.h"
  52 #include "jvmtifiles/jvmti.h"
  53 #include "klass.inline.hpp"
  54 #include "logging/log.hpp"
  55 #include "logging/logMessage.hpp"
  56 #include "logging/logStream.hpp"
  57 #include "memory/allocation.inline.hpp"
  58 #include "memory/iterator.inline.hpp"
  59 #include "memory/metadataFactory.hpp"
  60 #include "memory/metaspaceClosure.hpp"
  61 #include "memory/oopFactory.hpp"
  62 #include "memory/resourceArea.hpp"
  63 #include "memory/universe.hpp"
  64 #include "oops/constantPool.hpp"
  65 #include "oops/fieldStreams.inline.hpp"
  66 #include "oops/instanceClassLoaderKlass.hpp"
  67 #include "oops/instanceKlass.inline.hpp"
  68 #include "oops/instanceMirrorKlass.hpp"
  69 #include "oops/instanceOop.hpp"
  70 #include "oops/instanceStackChunkKlass.hpp"
  71 #include "oops/klass.inline.hpp"
  72 #include "oops/method.hpp"
  73 #include "oops/oop.inline.hpp"
  74 #include "oops/recordComponent.hpp"
  75 #include "oops/symbol.hpp"
  76 #include "prims/jvmtiExport.hpp"
  77 #include "prims/jvmtiRedefineClasses.hpp"
  78 #include "prims/jvmtiThreadState.hpp"
  79 #include "prims/methodComparator.hpp"
  80 #include "runtime/arguments.hpp"
  81 #include "runtime/atomicAccess.hpp"
  82 #include "runtime/deoptimization.hpp"
  83 #include "runtime/fieldDescriptor.inline.hpp"
  84 #include "runtime/handles.inline.hpp"
  85 #include "runtime/javaCalls.hpp"
  86 #include "runtime/javaThread.inline.hpp"
  87 #include "runtime/mutexLocker.hpp"
  88 #include "runtime/orderAccess.hpp"
  89 #include "runtime/os.inline.hpp"
  90 #include "runtime/reflection.hpp"
  91 #include "runtime/synchronizer.hpp"
  92 #include "runtime/threads.hpp"
  93 #include "services/classLoadingService.hpp"
  94 #include "services/finalizerService.hpp"
  95 #include "services/threadService.hpp"
  96 #include "utilities/dtrace.hpp"
  97 #include "utilities/events.hpp"
  98 #include "utilities/macros.hpp"
  99 #include "utilities/nativeStackPrinter.hpp"
 100 #include "utilities/stringUtils.hpp"
 101 #ifdef COMPILER1
 102 #include "c1/c1_Compiler.hpp"
 103 #endif
 104 #if INCLUDE_JFR
 105 #include "jfr/jfrEvents.hpp"
 106 #endif
 107 
 108 #ifdef DTRACE_ENABLED
 109 
 110 
 111 #define HOTSPOT_CLASS_INITIALIZATION_required HOTSPOT_CLASS_INITIALIZATION_REQUIRED
 112 #define HOTSPOT_CLASS_INITIALIZATION_recursive HOTSPOT_CLASS_INITIALIZATION_RECURSIVE
 113 #define HOTSPOT_CLASS_INITIALIZATION_concurrent HOTSPOT_CLASS_INITIALIZATION_CONCURRENT
 114 #define HOTSPOT_CLASS_INITIALIZATION_erroneous HOTSPOT_CLASS_INITIALIZATION_ERRONEOUS
 115 #define HOTSPOT_CLASS_INITIALIZATION_super__failed HOTSPOT_CLASS_INITIALIZATION_SUPER_FAILED
 116 #define HOTSPOT_CLASS_INITIALIZATION_clinit HOTSPOT_CLASS_INITIALIZATION_CLINIT
 117 #define HOTSPOT_CLASS_INITIALIZATION_error HOTSPOT_CLASS_INITIALIZATION_ERROR
 118 #define HOTSPOT_CLASS_INITIALIZATION_end HOTSPOT_CLASS_INITIALIZATION_END
 119 #define DTRACE_CLASSINIT_PROBE(type, thread_type)                \
 120   {                                                              \
 121     char* data = nullptr;                                        \
 122     int len = 0;                                                 \
 123     Symbol* clss_name = name();                                  \
 124     if (clss_name != nullptr) {                                  \
 125       data = (char*)clss_name->bytes();                          \
 126       len = clss_name->utf8_length();                            \
 127     }                                                            \
 128     HOTSPOT_CLASS_INITIALIZATION_##type(                         \
 129       data, len, (void*)class_loader(), thread_type);            \
 130   }
 131 
 132 #define DTRACE_CLASSINIT_PROBE_WAIT(type, thread_type, wait)     \
 133   {                                                              \
 134     char* data = nullptr;                                        \
 135     int len = 0;                                                 \
 136     Symbol* clss_name = name();                                  \
 137     if (clss_name != nullptr) {                                  \
 138       data = (char*)clss_name->bytes();                          \
 139       len = clss_name->utf8_length();                            \
 140     }                                                            \
 141     HOTSPOT_CLASS_INITIALIZATION_##type(                         \
 142       data, len, (void*)class_loader(), thread_type, wait);      \
 143   }
 144 
 145 #else //  ndef DTRACE_ENABLED
 146 
 147 #define DTRACE_CLASSINIT_PROBE(type, thread_type)
 148 #define DTRACE_CLASSINIT_PROBE_WAIT(type, thread_type, wait)
 149 
 150 #endif //  ndef DTRACE_ENABLED
 151 
 152 bool InstanceKlass::_finalization_enabled = true;
 153 
 154 static inline bool is_class_loader(const Symbol* class_name,
 155                                    const ClassFileParser& parser) {
 156   assert(class_name != nullptr, "invariant");
 157 
 158   if (class_name == vmSymbols::java_lang_ClassLoader()) {
 159     return true;
 160   }
 161 
 162   if (vmClasses::ClassLoader_klass_is_loaded()) {
 163     const Klass* const super_klass = parser.super_klass();
 164     if (super_klass != nullptr) {
 165       if (super_klass->is_subtype_of(vmClasses::ClassLoader_klass())) {
 166         return true;
 167       }
 168     }
 169   }
 170   return false;
 171 }
 172 
 173 static inline bool is_stack_chunk_class(const Symbol* class_name,
 174                                         const ClassLoaderData* loader_data) {
 175   return (class_name == vmSymbols::jdk_internal_vm_StackChunk() &&
 176           loader_data->is_the_null_class_loader_data());
 177 }
 178 
 179 // private: called to verify that k is a static member of this nest.
 180 // We know that k is an instance class in the same package and hence the
 181 // same classloader.
 182 bool InstanceKlass::has_nest_member(JavaThread* current, InstanceKlass* k) const {
 183   assert(!is_hidden(), "unexpected hidden class");
 184   if (_nest_members == nullptr || _nest_members == Universe::the_empty_short_array()) {
 185     if (log_is_enabled(Trace, class, nestmates)) {
 186       ResourceMark rm(current);
 187       log_trace(class, nestmates)("Checked nest membership of %s in non-nest-host class %s",
 188                                   k->external_name(), this->external_name());
 189     }
 190     return false;
 191   }
 192 
 193   if (log_is_enabled(Trace, class, nestmates)) {
 194     ResourceMark rm(current);
 195     log_trace(class, nestmates)("Checking nest membership of %s in %s",
 196                                 k->external_name(), this->external_name());
 197   }
 198 
 199   // Check for the named class in _nest_members.
 200   // We don't resolve, or load, any classes.
 201   for (int i = 0; i < _nest_members->length(); i++) {
 202     int cp_index = _nest_members->at(i);
 203     Symbol* name = _constants->klass_name_at(cp_index);
 204     if (name == k->name()) {
 205       log_trace(class, nestmates)("- named class found at nest_members[%d] => cp[%d]", i, cp_index);
 206       return true;
 207     }
 208   }
 209   log_trace(class, nestmates)("- class is NOT a nest member!");
 210   return false;
 211 }
 212 
 213 // Called to verify that k is a permitted subclass of this class.
 214 // The incoming stringStream is used to format the messages for error logging and for the caller
 215 // to use for exception throwing.
 216 bool InstanceKlass::has_as_permitted_subclass(const InstanceKlass* k, stringStream& ss) const {
 217   Thread* current = Thread::current();
 218   assert(k != nullptr, "sanity check");
 219   assert(_permitted_subclasses != nullptr && _permitted_subclasses != Universe::the_empty_short_array(),
 220          "unexpected empty _permitted_subclasses array");
 221 
 222   if (log_is_enabled(Trace, class, sealed)) {
 223     ResourceMark rm(current);
 224     log_trace(class, sealed)("Checking for permitted subclass %s in %s",
 225                              k->external_name(), this->external_name());
 226   }
 227 
 228   // Check that the class and its super are in the same module.
 229   if (k->module() != this->module()) {
 230     ss.print("Failed same module check: subclass %s is in module '%s' with loader %s, "
 231              "and sealed class %s is in module '%s' with loader %s",
 232              k->external_name(),
 233              k->module()->name_as_C_string(),
 234              k->module()->loader_data()->loader_name_and_id(),
 235              this->external_name(),
 236              this->module()->name_as_C_string(),
 237              this->module()->loader_data()->loader_name_and_id());
 238     log_trace(class, sealed)(" - %s", ss.as_string());
 239     return false;
 240   }
 241 
 242   if (!k->is_public() && !is_same_class_package(k)) {
 243     ss.print("Failed same package check: non-public subclass %s is in package '%s' with classloader %s, "
 244              "and sealed class %s is in package '%s' with classloader %s",
 245              k->external_name(),
 246              k->package() != nullptr ? k->package()->name()->as_C_string() : "unnamed",
 247              k->module()->loader_data()->loader_name_and_id(),
 248              this->external_name(),
 249              this->package() != nullptr ? this->package()->name()->as_C_string() : "unnamed",
 250              this->module()->loader_data()->loader_name_and_id());
 251     log_trace(class, sealed)(" - %s", ss.as_string());
 252     return false;
 253   }
 254 
 255   for (int i = 0; i < _permitted_subclasses->length(); i++) {
 256     int cp_index = _permitted_subclasses->at(i);
 257     Symbol* name = _constants->klass_name_at(cp_index);
 258     if (name == k->name()) {
 259       log_trace(class, sealed)("- Found it at permitted_subclasses[%d] => cp[%d]", i, cp_index);
 260       return true;
 261     }
 262   }
 263 
 264   ss.print("Failed listed permitted subclass check: class %s is not a permitted subclass of %s",
 265            k->external_name(), this->external_name());
 266   log_trace(class, sealed)(" - %s", ss.as_string());
 267   return false;
 268 }
 269 
 270 // Return nest-host class, resolving, validating and saving it if needed.
 271 // In cases where this is called from a thread that cannot do classloading
 272 // (such as a native JIT thread) then we simply return null, which in turn
 273 // causes the access check to return false. Such code will retry the access
 274 // from a more suitable environment later. Otherwise the _nest_host is always
 275 // set once this method returns.
 276 // Any errors from nest-host resolution must be preserved so they can be queried
 277 // from higher-level access checking code, and reported as part of access checking
 278 // exceptions.
 279 // VirtualMachineErrors are propagated with a null return.
 280 // Under any conditions where the _nest_host can be set to non-null the resulting
 281 // value of it and, if applicable, the nest host resolution/validation error,
 282 // are idempotent.
 283 InstanceKlass* InstanceKlass::nest_host(TRAPS) {
 284   InstanceKlass* nest_host_k = _nest_host;
 285   if (nest_host_k != nullptr) {
 286     return nest_host_k;
 287   }
 288 
 289   ResourceMark rm(THREAD);
 290 
 291   // need to resolve and save our nest-host class.
 292   if (_nest_host_index != 0) { // we have a real nest_host
 293     // Before trying to resolve check if we're in a suitable context
 294     bool can_resolve = THREAD->can_call_java();
 295     if (!can_resolve && !_constants->tag_at(_nest_host_index).is_klass()) {
 296       log_trace(class, nestmates)("Rejected resolution of nest-host of %s in unsuitable thread",
 297                                   this->external_name());
 298       return nullptr; // sentinel to say "try again from a different context"
 299     }
 300 
 301     log_trace(class, nestmates)("Resolving nest-host of %s using cp entry for %s",
 302                                 this->external_name(),
 303                                 _constants->klass_name_at(_nest_host_index)->as_C_string());
 304 
 305     Klass* k = _constants->klass_at(_nest_host_index, THREAD);
 306     if (HAS_PENDING_EXCEPTION) {
 307       if (PENDING_EXCEPTION->is_a(vmClasses::VirtualMachineError_klass())) {
 308         return nullptr; // propagate VMEs
 309       }
 310       stringStream ss;
 311       char* target_host_class = _constants->klass_name_at(_nest_host_index)->as_C_string();
 312       ss.print("Nest host resolution of %s with host %s failed: ",
 313                this->external_name(), target_host_class);
 314       java_lang_Throwable::print(PENDING_EXCEPTION, &ss);
 315       constantPoolHandle cph(THREAD, constants());
 316       SystemDictionary::add_nest_host_error(cph, _nest_host_index, ss);
 317       CLEAR_PENDING_EXCEPTION;
 318 
 319       log_trace(class, nestmates)("%s", ss.base());
 320     } else {
 321       // A valid nest-host is an instance class in the current package that lists this
 322       // class as a nest member. If any of these conditions are not met the class is
 323       // its own nest-host.
 324       const char* error = nullptr;
 325 
 326       // JVMS 5.4.4 indicates package check comes first
 327       if (is_same_class_package(k)) {
 328         // Now check actual membership. We can't be a member if our "host" is
 329         // not an instance class.
 330         if (k->is_instance_klass()) {
 331           nest_host_k = InstanceKlass::cast(k);
 332           bool is_member = nest_host_k->has_nest_member(THREAD, this);
 333           if (is_member) {
 334             _nest_host = nest_host_k; // save resolved nest-host value
 335 
 336             log_trace(class, nestmates)("Resolved nest-host of %s to %s",
 337                                         this->external_name(), k->external_name());
 338             return nest_host_k;
 339           } else {
 340             error = "current type is not listed as a nest member";
 341           }
 342         } else {
 343           error = "host is not an instance class";
 344         }
 345       } else {
 346         error = "types are in different packages";
 347       }
 348 
 349       // something went wrong, so record what and log it
 350       {
 351         stringStream ss;
 352         ss.print("Type %s (loader: %s) is not a nest member of type %s (loader: %s): %s",
 353                  this->external_name(),
 354                  this->class_loader_data()->loader_name_and_id(),
 355                  k->external_name(),
 356                  k->class_loader_data()->loader_name_and_id(),
 357                  error);
 358         constantPoolHandle cph(THREAD, constants());
 359         SystemDictionary::add_nest_host_error(cph, _nest_host_index, ss);
 360         log_trace(class, nestmates)("%s", ss.base());
 361       }
 362     }
 363   } else {
 364     log_trace(class, nestmates)("Type %s is not part of a nest: setting nest-host to self",
 365                                 this->external_name());
 366   }
 367 
 368   // Either not in an explicit nest, or else an error occurred, so
 369   // the nest-host is set to `this`. Any thread that sees this assignment
 370   // will also see any setting of nest_host_error(), if applicable.
 371   return (_nest_host = this);
 372 }
 373 
 374 // Dynamic nest member support: set this class's nest host to the given class.
 375 // This occurs as part of the class definition, as soon as the instanceKlass
 376 // has been created and doesn't require further resolution. The code:
 377 //    lookup().defineHiddenClass(bytes_for_X, NESTMATE);
 378 // results in:
 379 //    class_of_X.set_nest_host(lookup().lookupClass().getNestHost())
 380 // If it has an explicit _nest_host_index or _nest_members, these will be ignored.
 381 // We also know the "host" is a valid nest-host in the same package so we can
 382 // assert some of those facts.
 383 void InstanceKlass::set_nest_host(InstanceKlass* host) {
 384   assert(is_hidden(), "must be a hidden class");
 385   assert(host != nullptr, "null nest host specified");
 386   assert(_nest_host == nullptr, "current class has resolved nest-host");
 387   assert(nest_host_error() == nullptr, "unexpected nest host resolution error exists: %s",
 388          nest_host_error());
 389   assert((host->_nest_host == nullptr && host->_nest_host_index == 0) ||
 390          (host->_nest_host == host), "proposed host is not a valid nest-host");
 391   // Can't assert this as package is not set yet:
 392   // assert(is_same_class_package(host), "proposed host is in wrong package");
 393 
 394   if (log_is_enabled(Trace, class, nestmates)) {
 395     ResourceMark rm;
 396     const char* msg = "";
 397     // a hidden class does not expect a statically defined nest-host
 398     if (_nest_host_index > 0) {
 399       msg = "(the NestHost attribute in the current class is ignored)";
 400     } else if (_nest_members != nullptr && _nest_members != Universe::the_empty_short_array()) {
 401       msg = "(the NestMembers attribute in the current class is ignored)";
 402     }
 403     log_trace(class, nestmates)("Injected type %s into the nest of %s %s",
 404                                 this->external_name(),
 405                                 host->external_name(),
 406                                 msg);
 407   }
 408   // set dynamic nest host
 409   _nest_host = host;
 410   // Record dependency to keep nest host from being unloaded before this class.
 411   ClassLoaderData* this_key = class_loader_data();
 412   assert(this_key != nullptr, "sanity");
 413   this_key->record_dependency(host);
 414 }
 415 
 416 // check if 'this' and k are nestmates (same nest_host), or k is our nest_host,
 417 // or we are k's nest_host - all of which is covered by comparing the two
 418 // resolved_nest_hosts.
 419 // Any exceptions (i.e. VMEs) are propagated.
 420 bool InstanceKlass::has_nestmate_access_to(InstanceKlass* k, TRAPS) {
 421 
 422   assert(this != k, "this should be handled by higher-level code");
 423 
 424   // Per JVMS 5.4.4 we first resolve and validate the current class, then
 425   // the target class k.
 426 
 427   InstanceKlass* cur_host = nest_host(CHECK_false);
 428   if (cur_host == nullptr) {
 429     return false;
 430   }
 431 
 432   Klass* k_nest_host = k->nest_host(CHECK_false);
 433   if (k_nest_host == nullptr) {
 434     return false;
 435   }
 436 
 437   bool access = (cur_host == k_nest_host);
 438 
 439   ResourceMark rm(THREAD);
 440   log_trace(class, nestmates)("Class %s does %shave nestmate access to %s",
 441                               this->external_name(),
 442                               access ? "" : "NOT ",
 443                               k->external_name());
 444   return access;
 445 }
 446 
 447 const char* InstanceKlass::nest_host_error() {
 448   if (_nest_host_index == 0) {
 449     return nullptr;
 450   } else {
 451     constantPoolHandle cph(Thread::current(), constants());
 452     return SystemDictionary::find_nest_host_error(cph, (int)_nest_host_index);
 453   }
 454 }
 455 
 456 InstanceKlass* InstanceKlass::allocate_instance_klass(const ClassFileParser& parser, TRAPS) {
 457   const int size = InstanceKlass::size(parser.vtable_size(),
 458                                        parser.itable_size(),
 459                                        nonstatic_oop_map_size(parser.total_oop_map_count()),
 460                                        parser.is_interface());
 461 
 462   const Symbol* const class_name = parser.class_name();
 463   assert(class_name != nullptr, "invariant");
 464   ClassLoaderData* loader_data = parser.loader_data();
 465   assert(loader_data != nullptr, "invariant");
 466 
 467   InstanceKlass* ik;
 468 
 469   // Allocation
 470   if (parser.is_instance_ref_klass()) {
 471     // java.lang.ref.Reference
 472     ik = new (loader_data, size, THREAD) InstanceRefKlass(parser);
 473   } else if (class_name == vmSymbols::java_lang_Class()) {
 474     // mirror - java.lang.Class
 475     ik = new (loader_data, size, THREAD) InstanceMirrorKlass(parser);
 476   } else if (is_stack_chunk_class(class_name, loader_data)) {
 477     // stack chunk
 478     ik = new (loader_data, size, THREAD) InstanceStackChunkKlass(parser);
 479   } else if (is_class_loader(class_name, parser)) {
 480     // class loader - java.lang.ClassLoader
 481     ik = new (loader_data, size, THREAD) InstanceClassLoaderKlass(parser);
 482   } else {
 483     // normal
 484     ik = new (loader_data, size, THREAD) InstanceKlass(parser);
 485   }
 486 
 487   if (ik != nullptr && UseCompressedClassPointers) {
 488     assert(CompressedKlassPointers::is_encodable(ik),
 489            "Klass " PTR_FORMAT "needs a narrow Klass ID, but is not encodable", p2i(ik));
 490   }
 491 
 492   // Check for pending exception before adding to the loader data and incrementing
 493   // class count.  Can get OOM here.
 494   if (HAS_PENDING_EXCEPTION) {
 495     return nullptr;
 496   }
 497 
 498   return ik;
 499 }
 500 
 501 
 502 // copy method ordering from resource area to Metaspace
 503 void InstanceKlass::copy_method_ordering(const intArray* m, TRAPS) {
 504   if (m != nullptr) {
 505     // allocate a new array and copy contents (memcpy?)
 506     _method_ordering = MetadataFactory::new_array<int>(class_loader_data(), m->length(), CHECK);
 507     for (int i = 0; i < m->length(); i++) {
 508       _method_ordering->at_put(i, m->at(i));
 509     }
 510   } else {
 511     _method_ordering = Universe::the_empty_int_array();
 512   }
 513 }
 514 
 515 // create a new array of vtable_indices for default methods
 516 Array<int>* InstanceKlass::create_new_default_vtable_indices(int len, TRAPS) {
 517   Array<int>* vtable_indices = MetadataFactory::new_array<int>(class_loader_data(), len, CHECK_NULL);
 518   assert(default_vtable_indices() == nullptr, "only create once");
 519   set_default_vtable_indices(vtable_indices);
 520   return vtable_indices;
 521 }
 522 
 523 
 524 InstanceKlass::InstanceKlass() {
 525   assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for CDS");
 526 }
 527 
 528 InstanceKlass::InstanceKlass(const ClassFileParser& parser, KlassKind kind, ReferenceType reference_type) :
 529   Klass(kind),
 530   _nest_members(nullptr),
 531   _nest_host(nullptr),
 532   _permitted_subclasses(nullptr),
 533   _record_components(nullptr),
 534   _static_field_size(parser.static_field_size()),
 535   _nonstatic_oop_map_size(nonstatic_oop_map_size(parser.total_oop_map_count())),
 536   _itable_len(parser.itable_size()),
 537   _nest_host_index(0),
 538   _init_state(allocated),
 539   _reference_type(reference_type),
 540   _init_thread(nullptr),
 541   _hash_offset(parser.hash_offset())
 542 {
 543   set_vtable_length(parser.vtable_size());
 544   set_access_flags(parser.access_flags());
 545   if (parser.is_hidden()) set_is_hidden();
 546   set_layout_helper(Klass::instance_layout_helper(parser.layout_size(),
 547                                                     false));
 548 
 549   assert(nullptr == _methods, "underlying memory not zeroed?");
 550   assert(is_instance_klass(), "is layout incorrect?");
 551   assert(size_helper() == parser.layout_size(), "incorrect size_helper?");
 552 }
 553 
 554 void InstanceKlass::set_is_cloneable() {
 555   if (name() == vmSymbols::java_lang_invoke_MemberName()) {
 556     assert(is_final(), "no subclasses allowed");
 557     // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
 558   } else if (reference_type() != REF_NONE) {
 559     // Reference cloning should not be intrinsified and always happen in JVM_Clone.
 560   } else {
 561     set_is_cloneable_fast();
 562   }
 563 }
 564 
 565 void InstanceKlass::deallocate_methods(ClassLoaderData* loader_data,
 566                                        Array<Method*>* methods) {
 567   if (methods != nullptr && methods != Universe::the_empty_method_array() &&
 568       !methods->in_aot_cache()) {
 569     for (int i = 0; i < methods->length(); i++) {
 570       Method* method = methods->at(i);
 571       if (method == nullptr) continue;  // maybe null if error processing
 572       // Only want to delete methods that are not executing for RedefineClasses.
 573       // The previous version will point to them so they're not totally dangling
 574       assert (!method->on_stack(), "shouldn't be called with methods on stack");
 575       MetadataFactory::free_metadata(loader_data, method);
 576     }
 577     MetadataFactory::free_array<Method*>(loader_data, methods);
 578   }
 579 }
 580 
 581 void InstanceKlass::deallocate_interfaces(ClassLoaderData* loader_data,
 582                                           const InstanceKlass* super_klass,
 583                                           Array<InstanceKlass*>* local_interfaces,
 584                                           Array<InstanceKlass*>* transitive_interfaces) {
 585   // Only deallocate transitive interfaces if not empty, same as super class
 586   // or same as local interfaces.  See code in parseClassFile.
 587   Array<InstanceKlass*>* ti = transitive_interfaces;
 588   if (ti != Universe::the_empty_instance_klass_array() && ti != local_interfaces) {
 589     // check that the interfaces don't come from super class
 590     Array<InstanceKlass*>* sti = (super_klass == nullptr) ? nullptr :
 591                     super_klass->transitive_interfaces();
 592     if (ti != sti && ti != nullptr && !ti->in_aot_cache()) {
 593       MetadataFactory::free_array<InstanceKlass*>(loader_data, ti);
 594     }
 595   }
 596 
 597   // local interfaces can be empty
 598   if (local_interfaces != Universe::the_empty_instance_klass_array() &&
 599       local_interfaces != nullptr && !local_interfaces->in_aot_cache()) {
 600     MetadataFactory::free_array<InstanceKlass*>(loader_data, local_interfaces);
 601   }
 602 }
 603 
 604 void InstanceKlass::deallocate_record_components(ClassLoaderData* loader_data,
 605                                                  Array<RecordComponent*>* record_components) {
 606   if (record_components != nullptr && !record_components->in_aot_cache()) {
 607     for (int i = 0; i < record_components->length(); i++) {
 608       RecordComponent* record_component = record_components->at(i);
 609       MetadataFactory::free_metadata(loader_data, record_component);
 610     }
 611     MetadataFactory::free_array<RecordComponent*>(loader_data, record_components);
 612   }
 613 }
 614 
 615 // This function deallocates the metadata and C heap pointers that the
 616 // InstanceKlass points to.
 617 void InstanceKlass::deallocate_contents(ClassLoaderData* loader_data) {
 618   // Orphan the mirror first, CMS thinks it's still live.
 619   if (java_mirror() != nullptr) {
 620     java_lang_Class::set_klass(java_mirror(), nullptr);
 621   }
 622 
 623   // Also remove mirror from handles
 624   loader_data->remove_handle(_java_mirror);
 625 
 626   // Need to take this class off the class loader data list.
 627   loader_data->remove_class(this);
 628 
 629   // The array_klass for this class is created later, after error handling.
 630   // For class redefinition, we keep the original class so this scratch class
 631   // doesn't have an array class.  Either way, assert that there is nothing
 632   // to deallocate.
 633   assert(array_klasses() == nullptr, "array classes shouldn't be created for this class yet");
 634 
 635   // Release C heap allocated data that this points to, which includes
 636   // reference counting symbol names.
 637   // Can't release the constant pool or MethodData C heap data here because the constant
 638   // pool can be deallocated separately from the InstanceKlass for default methods and
 639   // redefine classes.  MethodData can also be released separately.
 640   release_C_heap_structures(/* release_sub_metadata */ false);
 641 
 642   deallocate_methods(loader_data, methods());
 643   set_methods(nullptr);
 644 
 645   deallocate_record_components(loader_data, record_components());
 646   set_record_components(nullptr);
 647 
 648   if (method_ordering() != nullptr &&
 649       method_ordering() != Universe::the_empty_int_array() &&
 650       !method_ordering()->in_aot_cache()) {
 651     MetadataFactory::free_array<int>(loader_data, method_ordering());
 652   }
 653   set_method_ordering(nullptr);
 654 
 655   // default methods can be empty
 656   if (default_methods() != nullptr &&
 657       default_methods() != Universe::the_empty_method_array() &&
 658       !default_methods()->in_aot_cache()) {
 659     MetadataFactory::free_array<Method*>(loader_data, default_methods());
 660   }
 661   // Do NOT deallocate the default methods, they are owned by superinterfaces.
 662   set_default_methods(nullptr);
 663 
 664   // default methods vtable indices can be empty
 665   if (default_vtable_indices() != nullptr &&
 666       !default_vtable_indices()->in_aot_cache()) {
 667     MetadataFactory::free_array<int>(loader_data, default_vtable_indices());
 668   }
 669   set_default_vtable_indices(nullptr);
 670 
 671 
 672   // This array is in Klass, but remove it with the InstanceKlass since
 673   // this place would be the only caller and it can share memory with transitive
 674   // interfaces.
 675   if (secondary_supers() != nullptr &&
 676       secondary_supers() != Universe::the_empty_klass_array() &&
 677       // see comments in compute_secondary_supers about the following cast
 678       (address)(secondary_supers()) != (address)(transitive_interfaces()) &&
 679       !secondary_supers()->in_aot_cache()) {
 680     MetadataFactory::free_array<Klass*>(loader_data, secondary_supers());
 681   }
 682   set_secondary_supers(nullptr, SECONDARY_SUPERS_BITMAP_EMPTY);
 683 
 684   deallocate_interfaces(loader_data, super(), local_interfaces(), transitive_interfaces());
 685   set_transitive_interfaces(nullptr);
 686   set_local_interfaces(nullptr);
 687 
 688   if (fieldinfo_stream() != nullptr && !fieldinfo_stream()->in_aot_cache()) {
 689     MetadataFactory::free_array<u1>(loader_data, fieldinfo_stream());
 690   }
 691   set_fieldinfo_stream(nullptr);
 692 
 693   if (fieldinfo_search_table() != nullptr && !fieldinfo_search_table()->in_aot_cache()) {
 694     MetadataFactory::free_array<u1>(loader_data, fieldinfo_search_table());
 695   }
 696   set_fieldinfo_search_table(nullptr);
 697 
 698   if (fields_status() != nullptr && !fields_status()->in_aot_cache()) {
 699     MetadataFactory::free_array<FieldStatus>(loader_data, fields_status());
 700   }
 701   set_fields_status(nullptr);
 702 
 703   // If a method from a redefined class is using this constant pool, don't
 704   // delete it, yet.  The new class's previous version will point to this.
 705   if (constants() != nullptr) {
 706     assert (!constants()->on_stack(), "shouldn't be called if anything is onstack");
 707     if (!constants()->in_aot_cache()) {
 708       MetadataFactory::free_metadata(loader_data, constants());
 709     }
 710     // Delete any cached resolution errors for the constant pool
 711     SystemDictionary::delete_resolution_error(constants());
 712 
 713     set_constants(nullptr);
 714   }
 715 
 716   if (inner_classes() != nullptr &&
 717       inner_classes() != Universe::the_empty_short_array() &&
 718       !inner_classes()->in_aot_cache()) {
 719     MetadataFactory::free_array<jushort>(loader_data, inner_classes());
 720   }
 721   set_inner_classes(nullptr);
 722 
 723   if (nest_members() != nullptr &&
 724       nest_members() != Universe::the_empty_short_array() &&
 725       !nest_members()->in_aot_cache()) {
 726     MetadataFactory::free_array<jushort>(loader_data, nest_members());
 727   }
 728   set_nest_members(nullptr);
 729 
 730   if (permitted_subclasses() != nullptr &&
 731       permitted_subclasses() != Universe::the_empty_short_array() &&
 732       !permitted_subclasses()->in_aot_cache()) {
 733     MetadataFactory::free_array<jushort>(loader_data, permitted_subclasses());
 734   }
 735   set_permitted_subclasses(nullptr);
 736 
 737   // We should deallocate the Annotations instance if it's not in shared spaces.
 738   if (annotations() != nullptr && !annotations()->in_aot_cache()) {
 739     MetadataFactory::free_metadata(loader_data, annotations());
 740   }
 741   set_annotations(nullptr);
 742 
 743   SystemDictionaryShared::handle_class_unloading(this);
 744 
 745 #if INCLUDE_CDS_JAVA_HEAP
 746   if (CDSConfig::is_dumping_heap()) {
 747     HeapShared::remove_scratch_objects(this);
 748   }
 749 #endif
 750 }
 751 
 752 bool InstanceKlass::is_record() const {
 753   return _record_components != nullptr &&
 754          is_final() &&
 755          super() == vmClasses::Record_klass();
 756 }
 757 
 758 bool InstanceKlass::is_sealed() const {
 759   return _permitted_subclasses != nullptr &&
 760          _permitted_subclasses != Universe::the_empty_short_array();
 761 }
 762 
 763 // JLS 8.9: An enum class is either implicitly final and derives
 764 // from java.lang.Enum, or else is implicitly sealed to its
 765 // anonymous subclasses. This query detects both kinds.
 766 // It does not validate the finality or
 767 // sealing conditions: it merely checks for a super of Enum.
 768 // This is sufficient for recognizing well-formed enums.
 769 bool InstanceKlass::is_enum_subclass() const {
 770   InstanceKlass* s = super();
 771   return (s == vmClasses::Enum_klass() ||
 772           (s != nullptr && s->super() == vmClasses::Enum_klass()));
 773 }
 774 
 775 bool InstanceKlass::should_be_initialized() const {
 776   return !is_initialized();
 777 }
 778 
 779 klassItable InstanceKlass::itable() const {
 780   return klassItable(const_cast<InstanceKlass*>(this));
 781 }
 782 
 783 // JVMTI spec thinks there are signers and protection domain in the
 784 // instanceKlass.  These accessors pretend these fields are there.
 785 // The hprof specification also thinks these fields are in InstanceKlass.
 786 oop InstanceKlass::protection_domain() const {
 787   // return the protection_domain from the mirror
 788   return java_lang_Class::protection_domain(java_mirror());
 789 }
 790 
 791 objArrayOop InstanceKlass::signers() const {
 792   // return the signers from the mirror
 793   return java_lang_Class::signers(java_mirror());
 794 }
 795 
 796 oop InstanceKlass::init_lock() const {
 797   // return the init lock from the mirror
 798   oop lock = java_lang_Class::init_lock(java_mirror());
 799   // Prevent reordering with any access of initialization state
 800   OrderAccess::loadload();
 801   assert(lock != nullptr || !is_not_initialized(), // initialized or in_error state
 802          "only fully initialized state can have a null lock");
 803   return lock;
 804 }
 805 
 806 // Set the initialization lock to null so the object can be GC'ed. Any racing
 807 // threads to get this lock will see a null lock and will not lock.
 808 // That's okay because they all check for initialized state after getting
 809 // the lock and return. For preempted vthreads we keep the oop protected
 810 // in the ObjectMonitor (see ObjectMonitor::set_object_strong()).
 811 void InstanceKlass::fence_and_clear_init_lock() {
 812   // make sure previous stores are all done, notably the init_state.
 813   OrderAccess::storestore();
 814   java_lang_Class::clear_init_lock(java_mirror());
 815   assert(!is_not_initialized(), "class must be initialized now");
 816 }
 817 
 818 class PreemptableInitCall {
 819   JavaThread* _thread;
 820   bool _previous;
 821   DEBUG_ONLY(InstanceKlass* _previous_klass;)
 822  public:
 823   PreemptableInitCall(JavaThread* thread, InstanceKlass* ik) : _thread(thread) {
 824     _previous = thread->at_preemptable_init();
 825     _thread->set_at_preemptable_init(true);
 826     DEBUG_ONLY(_previous_klass = _thread->preempt_init_klass();)
 827     DEBUG_ONLY(_thread->set_preempt_init_klass(ik));
 828   }
 829   ~PreemptableInitCall() {
 830     _thread->set_at_preemptable_init(_previous);
 831     DEBUG_ONLY(_thread->set_preempt_init_klass(_previous_klass));
 832   }
 833 };
 834 
 835 void InstanceKlass::initialize_preemptable(TRAPS) {
 836   if (this->should_be_initialized()) {
 837     PreemptableInitCall pic(THREAD, this);
 838     initialize_impl(THREAD);
 839   } else {
 840     assert(is_initialized(), "sanity check");
 841   }
 842 }
 843 
 844 // See "The Virtual Machine Specification" section 2.16.5 for a detailed explanation of the class initialization
 845 // process. The step comments refers to the procedure described in that section.
 846 // Note: implementation moved to static method to expose the this pointer.
 847 void InstanceKlass::initialize(TRAPS) {
 848   if (this->should_be_initialized()) {
 849     initialize_impl(CHECK);
 850     // Note: at this point the class may be initialized
 851     //       OR it may be in the state of being initialized
 852     //       in case of recursive initialization!
 853   } else {
 854     assert(is_initialized(), "sanity check");
 855   }
 856 }
 857 
 858 #ifdef ASSERT
 859 void InstanceKlass::assert_no_clinit_will_run_for_aot_initialized_class() const {
 860   assert(has_aot_initialized_mirror(), "must be");
 861 
 862   InstanceKlass* s = super();
 863   if (s != nullptr) {
 864     DEBUG_ONLY(ResourceMark rm);
 865     assert(s->is_initialized(), "super class %s of aot-inited class %s must have been initialized",
 866            s->external_name(), external_name());
 867     s->assert_no_clinit_will_run_for_aot_initialized_class();
 868   }
 869 
 870   Array<InstanceKlass*>* interfaces = local_interfaces();
 871   int len = interfaces->length();
 872   for (int i = 0; i < len; i++) {
 873     InstanceKlass* intf = interfaces->at(i);
 874     if (!intf->is_initialized()) {
 875       ResourceMark rm;
 876       // Note: an interface needs to be marked as is_initialized() only if
 877       // - it has a <clinit>
 878       // - it has declared a default method.
 879       assert(!intf->interface_needs_clinit_execution_as_super(/*also_check_supers*/false),
 880              "uninitialized super interface %s of aot-inited class %s must not have <clinit>",
 881              intf->external_name(), external_name());
 882     }
 883   }
 884 }
 885 #endif
 886 
 887 #if INCLUDE_CDS
 888 void InstanceKlass::initialize_with_aot_initialized_mirror(TRAPS) {
 889   assert(has_aot_initialized_mirror(), "must be");
 890   assert(CDSConfig::is_loading_heap(), "must be");
 891   assert(CDSConfig::is_using_aot_linked_classes(), "must be");
 892   assert_no_clinit_will_run_for_aot_initialized_class();
 893 
 894   if (is_initialized()) {
 895     return;
 896   }
 897 
 898   if (is_runtime_setup_required()) {
 899     // Need to take the slow path, which will call the runtimeSetup() function instead
 900     // of <clinit>
 901     initialize(CHECK);
 902     return;
 903   }
 904   if (log_is_enabled(Info, aot, init)) {
 905     ResourceMark rm;
 906     log_info(aot, init)("%s (aot-inited)", external_name());
 907   }
 908 
 909   link_class(CHECK);
 910 
 911 #ifdef ASSERT
 912   {
 913     Handle h_init_lock(THREAD, init_lock());
 914     ObjectLocker ol(h_init_lock, THREAD);
 915     assert(!is_initialized(), "sanity");
 916     assert(!is_being_initialized(), "sanity");
 917     assert(!is_in_error_state(), "sanity");
 918   }
 919 #endif
 920 
 921   set_init_thread(THREAD);
 922   set_initialization_state_and_notify(fully_initialized, CHECK);
 923 }
 924 #endif
 925 
 926 bool InstanceKlass::verify_code(TRAPS) {
 927   // 1) Verify the bytecodes
 928   return Verifier::verify(this, should_verify_class(), THREAD);
 929 }
 930 
 931 void InstanceKlass::link_class(TRAPS) {
 932   assert(is_loaded(), "must be loaded");
 933   if (!is_linked()) {
 934     link_class_impl(CHECK);
 935   }
 936 }
 937 
 938 // Called to verify that a class can link during initialization, without
 939 // throwing a VerifyError.
 940 bool InstanceKlass::link_class_or_fail(TRAPS) {
 941   assert(is_loaded(), "must be loaded");
 942   if (!is_linked()) {
 943     link_class_impl(CHECK_false);
 944   }
 945   return is_linked();
 946 }
 947 
 948 bool InstanceKlass::link_class_impl(TRAPS) {
 949   if (CDSConfig::is_dumping_static_archive() && SystemDictionaryShared::has_class_failed_verification(this)) {
 950     // This is for CDS static dump only -- we use the in_error_state to indicate that
 951     // the class has failed verification. Throwing the NoClassDefFoundError here is just
 952     // a convenient way to stop repeat attempts to verify the same (bad) class.
 953     //
 954     // Note that the NoClassDefFoundError is not part of the JLS, and should not be thrown
 955     // if we are executing Java code. This is not a problem for CDS dumping phase since
 956     // it doesn't execute any Java code.
 957     ResourceMark rm(THREAD);
 958     // Names are all known to be < 64k so we know this formatted message is not excessively large.
 959     Exceptions::fthrow(THREAD_AND_LOCATION,
 960                        vmSymbols::java_lang_NoClassDefFoundError(),
 961                        "Class %s, or one of its supertypes, failed class initialization",
 962                        external_name());
 963     return false;
 964   }
 965   // return if already verified
 966   if (is_linked()) {
 967     return true;
 968   }
 969 
 970   // Timing
 971   // timer handles recursion
 972   JavaThread* jt = THREAD;
 973 
 974   // link super class before linking this class
 975   InstanceKlass* super_klass = super();
 976   if (super_klass != nullptr) {
 977     if (super_klass->is_interface()) {  // check if super class is an interface
 978       ResourceMark rm(THREAD);
 979       // Names are all known to be < 64k so we know this formatted message is not excessively large.
 980       Exceptions::fthrow(
 981         THREAD_AND_LOCATION,
 982         vmSymbols::java_lang_IncompatibleClassChangeError(),
 983         "class %s has interface %s as super class",
 984         external_name(),
 985         super_klass->external_name()
 986       );
 987       return false;
 988     }
 989 
 990     super_klass->link_class_impl(CHECK_false);
 991   }
 992 
 993   // link all interfaces implemented by this class before linking this class
 994   Array<InstanceKlass*>* interfaces = local_interfaces();
 995   int num_interfaces = interfaces->length();
 996   for (int index = 0; index < num_interfaces; index++) {
 997     InstanceKlass* interk = interfaces->at(index);
 998     interk->link_class_impl(CHECK_false);
 999   }
1000 
1001   // in case the class is linked in the process of linking its superclasses
1002   if (is_linked()) {
1003     return true;
1004   }
1005 
1006   // trace only the link time for this klass that includes
1007   // the verification time
1008   PerfClassTraceTime vmtimer(ClassLoader::perf_class_link_time(),
1009                              ClassLoader::perf_class_link_selftime(),
1010                              ClassLoader::perf_classes_linked(),
1011                              jt->get_thread_stat()->perf_recursion_counts_addr(),
1012                              jt->get_thread_stat()->perf_timers_addr(),
1013                              PerfClassTraceTime::CLASS_LINK);
1014 
1015   // verification & rewriting
1016   {
1017     HandleMark hm(THREAD);
1018     Handle h_init_lock(THREAD, init_lock());
1019     ObjectLocker ol(h_init_lock, CHECK_PREEMPTABLE_false);
1020     // Don't allow preemption if we link/initialize classes below,
1021     // since that would release this monitor while we are in the
1022     // middle of linking this class.
1023     NoPreemptMark npm(THREAD);
1024 
1025     // rewritten will have been set if loader constraint error found
1026     // on an earlier link attempt
1027     // don't verify or rewrite if already rewritten
1028     //
1029 
1030     if (!is_linked()) {
1031       if (!is_rewritten()) {
1032         if (in_aot_cache()) {
1033           assert(!verified_at_dump_time(), "must be");
1034         }
1035         {
1036           bool verify_ok = verify_code(THREAD);
1037           if (!verify_ok) {
1038             return false;
1039           }
1040         }
1041 
1042         // Just in case a side-effect of verify linked this class already
1043         // (which can sometimes happen since the verifier loads classes
1044         // using custom class loaders, which are free to initialize things)
1045         if (is_linked()) {
1046           return true;
1047         }
1048 
1049         // also sets rewritten
1050         rewrite_class(CHECK_false);
1051       } else if (in_aot_cache()) {
1052         SystemDictionaryShared::check_verification_constraints(this, CHECK_false);
1053       }
1054 
1055       // relocate jsrs and link methods after they are all rewritten
1056       link_methods(CHECK_false);
1057 
1058       // Initialize the vtable and interface table after
1059       // methods have been rewritten since rewrite may
1060       // fabricate new Method*s.
1061       // also does loader constraint checking
1062       //
1063       // initialize_vtable and initialize_itable need to be rerun
1064       // for a shared class if
1065       // 1) the class is loaded by custom class loader or
1066       // 2) the class is loaded by built-in class loader but failed to add archived loader constraints or
1067       // 3) the class was not verified during dump time
1068       bool need_init_table = true;
1069       if (in_aot_cache() && verified_at_dump_time() &&
1070           SystemDictionaryShared::check_linking_constraints(THREAD, this)) {
1071         need_init_table = false;
1072       }
1073       if (need_init_table) {
1074         vtable().initialize_vtable_and_check_constraints(CHECK_false);
1075         itable().initialize_itable_and_check_constraints(CHECK_false);
1076       }
1077 #ifdef ASSERT
1078       vtable().verify(tty, true);
1079       // In case itable verification is ever added.
1080       // itable().verify(tty, true);
1081 #endif
1082       if (Universe::is_fully_initialized()) {
1083         DeoptimizationScope deopt_scope;
1084         {
1085           // Now mark all code that assumes the class is not linked.
1086           // Set state under the Compile_lock also.
1087           MutexLocker ml(THREAD, Compile_lock);
1088 
1089           set_init_state(linked);
1090           CodeCache::mark_dependents_on(&deopt_scope, this);
1091         }
1092         // Perform the deopt handshake outside Compile_lock.
1093         deopt_scope.deoptimize_marked();
1094       } else {
1095         set_init_state(linked);
1096       }
1097       if (JvmtiExport::should_post_class_prepare()) {
1098         JvmtiExport::post_class_prepare(THREAD, this);
1099       }
1100     }
1101   }
1102   return true;
1103 }
1104 
1105 // Rewrite the byte codes of all of the methods of a class.
1106 // The rewriter must be called exactly once. Rewriting must happen after
1107 // verification but before the first method of the class is executed.
1108 void InstanceKlass::rewrite_class(TRAPS) {
1109   assert(is_loaded(), "must be loaded");
1110   if (is_rewritten()) {
1111     assert(in_aot_cache(), "rewriting an unshared class?");
1112     return;
1113   }
1114   Rewriter::rewrite(this, CHECK);
1115   set_rewritten();
1116 }
1117 
1118 // Now relocate and link method entry points after class is rewritten.
1119 // This is outside is_rewritten flag. In case of an exception, it can be
1120 // executed more than once.
1121 void InstanceKlass::link_methods(TRAPS) {
1122   PerfTraceTime timer(ClassLoader::perf_ik_link_methods_time());
1123 
1124   int len = methods()->length();
1125   for (int i = len-1; i >= 0; i--) {
1126     methodHandle m(THREAD, methods()->at(i));
1127 
1128     // Set up method entry points for compiler and interpreter    .
1129     m->link_method(m, CHECK);
1130   }
1131 }
1132 
1133 // Eagerly initialize superinterfaces that declare default methods (concrete instance: any access)
1134 void InstanceKlass::initialize_super_interfaces(TRAPS) {
1135   assert (has_nonstatic_concrete_methods(), "caller should have checked this");
1136   for (int i = 0; i < local_interfaces()->length(); ++i) {
1137     InstanceKlass* ik = local_interfaces()->at(i);
1138 
1139     // Initialization is depth first search ie. we start with top of the inheritance tree
1140     // has_nonstatic_concrete_methods drives searching superinterfaces since it
1141     // means has_nonstatic_concrete_methods in its superinterface hierarchy
1142     if (ik->has_nonstatic_concrete_methods()) {
1143       ik->initialize_super_interfaces(CHECK);
1144     }
1145 
1146     // Only initialize() interfaces that "declare" concrete methods.
1147     if (ik->should_be_initialized() && ik->declares_nonstatic_concrete_methods()) {
1148       ik->initialize(CHECK);
1149     }
1150   }
1151 }
1152 
1153 using InitializationErrorTable = HashTable<const InstanceKlass*, OopHandle, 107, AnyObj::C_HEAP, mtClass>;
1154 static InitializationErrorTable* _initialization_error_table;
1155 
1156 void InstanceKlass::add_initialization_error(JavaThread* current, Handle exception) {
1157   // Create the same exception with a message indicating the thread name,
1158   // and the StackTraceElements.
1159   Handle init_error = java_lang_Throwable::create_initialization_error(current, exception);
1160   ResourceMark rm(current);
1161   if (init_error.is_null()) {
1162     log_trace(class, init)("Unable to create the desired initialization error for class %s", external_name());
1163 
1164     // We failed to create the new exception, most likely due to either out-of-memory or
1165     // a stackoverflow error. If the original exception was either of those then we save
1166     // the shared, pre-allocated, stackless, instance of that exception.
1167     if (exception->klass() == vmClasses::StackOverflowError_klass()) {
1168       log_debug(class, init)("Using shared StackOverflowError as initialization error for class %s", external_name());
1169       init_error = Handle(current, Universe::class_init_stack_overflow_error());
1170     } else if (exception->klass() == vmClasses::OutOfMemoryError_klass()) {
1171       log_debug(class, init)("Using shared OutOfMemoryError as initialization error for class %s", external_name());
1172       init_error = Handle(current, Universe::class_init_out_of_memory_error());
1173     } else {
1174       return;
1175     }
1176   }
1177 
1178   MutexLocker ml(current, ClassInitError_lock);
1179   OopHandle elem = OopHandle(Universe::vm_global(), init_error());
1180   bool created;
1181   if (_initialization_error_table == nullptr) {
1182     _initialization_error_table = new (mtClass) InitializationErrorTable();
1183   }
1184   _initialization_error_table->put_if_absent(this, elem, &created);
1185   assert(created, "Initialization is single threaded");
1186   log_trace(class, init)("Initialization error added for class %s", external_name());
1187 }
1188 
1189 oop InstanceKlass::get_initialization_error(JavaThread* current) {
1190   MutexLocker ml(current, ClassInitError_lock);
1191   if (_initialization_error_table == nullptr) {
1192     return nullptr;
1193   }
1194   OopHandle* h = _initialization_error_table->get(this);
1195   return (h != nullptr) ? h->resolve() : nullptr;
1196 }
1197 
1198 // Need to remove entries for unloaded classes.
1199 void InstanceKlass::clean_initialization_error_table() {
1200   struct InitErrorTableCleaner {
1201     bool do_entry(const InstanceKlass* ik, OopHandle h) {
1202       if (!ik->is_loader_alive()) {
1203         h.release(Universe::vm_global());
1204         return true;
1205       } else {
1206         return false;
1207       }
1208     }
1209   };
1210 
1211   assert_locked_or_safepoint(ClassInitError_lock);
1212   InitErrorTableCleaner cleaner;
1213   if (_initialization_error_table != nullptr) {
1214     _initialization_error_table->unlink(&cleaner);
1215   }
1216 }
1217 
1218 class ThreadWaitingForClassInit : public StackObj {
1219   JavaThread* _thread;
1220  public:
1221   ThreadWaitingForClassInit(JavaThread* thread, InstanceKlass* ik) : _thread(thread) {
1222     _thread->set_class_to_be_initialized(ik);
1223   }
1224   ~ThreadWaitingForClassInit() {
1225     _thread->set_class_to_be_initialized(nullptr);
1226   }
1227 };
1228 
1229 void InstanceKlass::initialize_impl(TRAPS) {
1230   HandleMark hm(THREAD);
1231 
1232   // Make sure klass is linked (verified) before initialization
1233   // A class could already be verified, since it has been reflected upon.
1234   link_class(CHECK);
1235 
1236   DTRACE_CLASSINIT_PROBE(required, -1);
1237 
1238   bool wait = false;
1239 
1240   JavaThread* jt = THREAD;
1241 
1242   bool debug_logging_enabled = log_is_enabled(Debug, class, init);
1243 
1244   // refer to the JVM book page 47 for description of steps
1245   // Step 1
1246   {
1247     Handle h_init_lock(THREAD, init_lock());
1248     ObjectLocker ol(h_init_lock, CHECK_PREEMPTABLE);
1249 
1250     // Step 2
1251     // If we were to use wait() instead of waitInterruptibly() then
1252     // we might end up throwing IE from link/symbol resolution sites
1253     // that aren't expected to throw.  This would wreak havoc.  See 6320309.
1254     while (is_being_initialized() && !is_reentrant_initialization(jt)) {
1255       if (debug_logging_enabled) {
1256         ResourceMark rm(jt);
1257         log_debug(class, init)("Thread \"%s\" waiting for initialization of %s by thread \"%s\"",
1258                                jt->name(), external_name(), init_thread_name());
1259       }
1260       wait = true;
1261       ThreadWaitingForClassInit twcl(THREAD, this);
1262       ol.wait_uninterruptibly(CHECK_PREEMPTABLE);
1263     }
1264 
1265     // Step 3
1266     if (is_being_initialized() && is_reentrant_initialization(jt)) {
1267       if (debug_logging_enabled) {
1268         ResourceMark rm(jt);
1269         log_debug(class, init)("Thread \"%s\" recursively initializing %s",
1270                                jt->name(), external_name());
1271       }
1272       DTRACE_CLASSINIT_PROBE_WAIT(recursive, -1, wait);
1273       return;
1274     }
1275 
1276     // Step 4
1277     if (is_initialized()) {
1278       if (debug_logging_enabled) {
1279         ResourceMark rm(jt);
1280         log_debug(class, init)("Thread \"%s\" found %s already initialized",
1281                                jt->name(), external_name());
1282       }
1283       DTRACE_CLASSINIT_PROBE_WAIT(concurrent, -1, wait);
1284       return;
1285     }
1286 
1287     // Step 5
1288     if (is_in_error_state()) {
1289       if (debug_logging_enabled) {
1290         ResourceMark rm(jt);
1291         log_debug(class, init)("Thread \"%s\" found %s is in error state",
1292                                jt->name(), external_name());
1293       }
1294 
1295       DTRACE_CLASSINIT_PROBE_WAIT(erroneous, -1, wait);
1296       ResourceMark rm(THREAD);
1297       Handle cause(THREAD, get_initialization_error(THREAD));
1298 
1299       stringStream ss;
1300       ss.print("Could not initialize class %s", external_name());
1301       if (cause.is_null()) {
1302         THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), ss.as_string());
1303       } else {
1304         THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(),
1305                         ss.as_string(), cause);
1306       }
1307     } else {
1308 
1309       // Step 6
1310       set_init_state(being_initialized);
1311       set_init_thread(jt);
1312       if (debug_logging_enabled) {
1313         ResourceMark rm(jt);
1314         log_debug(class, init)("Thread \"%s\" is initializing %s",
1315                                jt->name(), external_name());
1316       }
1317     }
1318   }
1319 
1320   // Block preemption once we are the initializer thread. Unmounting now
1321   // would complicate the reentrant case (identity is platform thread).
1322   NoPreemptMark npm(THREAD);
1323 
1324   // Step 7
1325   // Next, if C is a class rather than an interface, initialize it's super class and super
1326   // interfaces.
1327   if (!is_interface()) {
1328     Klass* super_klass = super();
1329     if (super_klass != nullptr && super_klass->should_be_initialized()) {
1330       super_klass->initialize(THREAD);
1331     }
1332     // If C implements any interface that declares a non-static, concrete method,
1333     // the initialization of C triggers initialization of its super interfaces.
1334     // Only need to recurse if has_nonstatic_concrete_methods which includes declaring and
1335     // having a superinterface that declares, non-static, concrete methods
1336     if (!HAS_PENDING_EXCEPTION && has_nonstatic_concrete_methods()) {
1337       initialize_super_interfaces(THREAD);
1338     }
1339 
1340     // If any exceptions, complete abruptly, throwing the same exception as above.
1341     if (HAS_PENDING_EXCEPTION) {
1342       Handle e(THREAD, PENDING_EXCEPTION);
1343       CLEAR_PENDING_EXCEPTION;
1344       {
1345         EXCEPTION_MARK;
1346         add_initialization_error(THREAD, e);
1347         // Locks object, set state, and notify all waiting threads
1348         set_initialization_state_and_notify(initialization_error, THREAD);
1349         CLEAR_PENDING_EXCEPTION;
1350       }
1351       DTRACE_CLASSINIT_PROBE_WAIT(super__failed, -1, wait);
1352       THROW_OOP(e());
1353     }
1354   }
1355 
1356 
1357   // Step 8
1358   {
1359     DTRACE_CLASSINIT_PROBE_WAIT(clinit, -1, wait);
1360     if (class_initializer() != nullptr) {
1361       // Timer includes any side effects of class initialization (resolution,
1362       // etc), but not recursive entry into call_class_initializer().
1363       PerfClassTraceTime timer(ClassLoader::perf_class_init_time(),
1364                                ClassLoader::perf_class_init_selftime(),
1365                                ClassLoader::perf_classes_inited(),
1366                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1367                                jt->get_thread_stat()->perf_timers_addr(),
1368                                PerfClassTraceTime::CLASS_CLINIT);
1369       call_class_initializer(THREAD);
1370     } else {
1371       // The elapsed time is so small it's not worth counting.
1372       if (UsePerfData) {
1373         ClassLoader::perf_classes_inited()->inc();
1374       }
1375       call_class_initializer(THREAD);
1376     }
1377   }
1378 
1379   // Step 9
1380   if (!HAS_PENDING_EXCEPTION) {
1381     set_initialization_state_and_notify(fully_initialized, CHECK);
1382     DEBUG_ONLY(vtable().verify(tty, true);)
1383     CompilationPolicy::replay_training_at_init(this, THREAD);
1384   }
1385   else {
1386     // Step 10 and 11
1387     Handle e(THREAD, PENDING_EXCEPTION);
1388     CLEAR_PENDING_EXCEPTION;
1389     // JVMTI has already reported the pending exception
1390     // JVMTI internal flag reset is needed in order to report ExceptionInInitializerError
1391     JvmtiExport::clear_detected_exception(jt);
1392     {
1393       EXCEPTION_MARK;
1394       add_initialization_error(THREAD, e);
1395       set_initialization_state_and_notify(initialization_error, THREAD);
1396       CLEAR_PENDING_EXCEPTION;   // ignore any exception thrown, class initialization error is thrown below
1397       // JVMTI has already reported the pending exception
1398       // JVMTI internal flag reset is needed in order to report ExceptionInInitializerError
1399       JvmtiExport::clear_detected_exception(jt);
1400     }
1401     DTRACE_CLASSINIT_PROBE_WAIT(error, -1, wait);
1402     if (e->is_a(vmClasses::Error_klass())) {
1403       THROW_OOP(e());
1404     } else {
1405       JavaCallArguments args(e);
1406       THROW_ARG(vmSymbols::java_lang_ExceptionInInitializerError(),
1407                 vmSymbols::throwable_void_signature(),
1408                 &args);
1409     }
1410   }
1411   DTRACE_CLASSINIT_PROBE_WAIT(end, -1, wait);
1412 }
1413 
1414 
1415 void InstanceKlass::set_initialization_state_and_notify(ClassState state, TRAPS) {
1416   Handle h_init_lock(THREAD, init_lock());
1417   if (h_init_lock() != nullptr) {
1418     ObjectLocker ol(h_init_lock, THREAD);
1419     set_init_thread(nullptr); // reset _init_thread before changing _init_state
1420     set_init_state(state);
1421     fence_and_clear_init_lock();
1422     ol.notify_all(CHECK);
1423   } else {
1424     assert(h_init_lock() != nullptr, "The initialization state should never be set twice");
1425     set_init_thread(nullptr); // reset _init_thread before changing _init_state
1426     set_init_state(state);
1427   }
1428 }
1429 
1430 // Update hierarchy. This is done before the new klass has been added to the SystemDictionary. The Compile_lock
1431 // is grabbed, to ensure that the compiler is not using the class hierarchy.
1432 void InstanceKlass::add_to_hierarchy(JavaThread* current) {
1433   assert(!SafepointSynchronize::is_at_safepoint(), "must NOT be at safepoint");
1434 
1435   DeoptimizationScope deopt_scope;
1436   {
1437     MutexLocker ml(current, Compile_lock);
1438 
1439     set_init_state(InstanceKlass::loaded);
1440     // make sure init_state store is already done.
1441     // The compiler reads the hierarchy outside of the Compile_lock.
1442     // Access ordering is used to add to hierarchy.
1443 
1444     // Link into hierarchy.
1445     append_to_sibling_list();                    // add to superklass/sibling list
1446     process_interfaces();                        // handle all "implements" declarations
1447 
1448     // Now mark all code that depended on old class hierarchy.
1449     // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1450     if (Universe::is_fully_initialized()) {
1451       CodeCache::mark_dependents_on(&deopt_scope, this);
1452     }
1453   }
1454   // Perform the deopt handshake outside Compile_lock.
1455   deopt_scope.deoptimize_marked();
1456 }
1457 
1458 
1459 InstanceKlass* InstanceKlass::implementor() const {
1460   InstanceKlass* volatile* ik = adr_implementor();
1461   if (ik == nullptr) {
1462     return nullptr;
1463   } else {
1464     // This load races with inserts, and therefore needs acquire.
1465     InstanceKlass* ikls = AtomicAccess::load_acquire(ik);
1466     if (ikls != nullptr && !ikls->is_loader_alive()) {
1467       return nullptr;  // don't return unloaded class
1468     } else {
1469       return ikls;
1470     }
1471   }
1472 }
1473 
1474 
1475 void InstanceKlass::set_implementor(InstanceKlass* ik) {
1476   assert_locked_or_safepoint(Compile_lock);
1477   assert(is_interface(), "not interface");
1478   InstanceKlass* volatile* addr = adr_implementor();
1479   assert(addr != nullptr, "null addr");
1480   if (addr != nullptr) {
1481     AtomicAccess::release_store(addr, ik);
1482   }
1483 }
1484 
1485 int  InstanceKlass::nof_implementors() const {
1486   InstanceKlass* ik = implementor();
1487   if (ik == nullptr) {
1488     return 0;
1489   } else if (ik != this) {
1490     return 1;
1491   } else {
1492     return 2;
1493   }
1494 }
1495 
1496 // The embedded _implementor field can only record one implementor.
1497 // When there are more than one implementors, the _implementor field
1498 // is set to the interface Klass* itself. Following are the possible
1499 // values for the _implementor field:
1500 //   null                  - no implementor
1501 //   implementor Klass*    - one implementor
1502 //   self                  - more than one implementor
1503 //
1504 // The _implementor field only exists for interfaces.
1505 void InstanceKlass::add_implementor(InstanceKlass* ik) {
1506   if (Universe::is_fully_initialized()) {
1507     assert_lock_strong(Compile_lock);
1508   }
1509   assert(is_interface(), "not interface");
1510   // Filter out my subinterfaces.
1511   // (Note: Interfaces are never on the subklass list.)
1512   if (ik->is_interface()) return;
1513 
1514   // Filter out subclasses whose supers already implement me.
1515   // (Note: CHA must walk subclasses of direct implementors
1516   // in order to locate indirect implementors.)
1517   InstanceKlass* super_ik = ik->super();
1518   if (super_ik != nullptr && super_ik->implements_interface(this))
1519     // We only need to check one immediate superclass, since the
1520     // implements_interface query looks at transitive_interfaces.
1521     // Any supers of the super have the same (or fewer) transitive_interfaces.
1522     return;
1523 
1524   InstanceKlass* iklass = implementor();
1525   if (iklass == nullptr) {
1526     set_implementor(ik);
1527   } else if (iklass != this && iklass != ik) {
1528     // There is already an implementor. Use itself as an indicator of
1529     // more than one implementors.
1530     set_implementor(this);
1531   }
1532 
1533   // The implementor also implements the transitive_interfaces
1534   for (int index = 0; index < local_interfaces()->length(); index++) {
1535     local_interfaces()->at(index)->add_implementor(ik);
1536   }
1537 }
1538 
1539 void InstanceKlass::init_implementor() {
1540   if (is_interface()) {
1541     set_implementor(nullptr);
1542   }
1543 }
1544 
1545 
1546 void InstanceKlass::process_interfaces() {
1547   // link this class into the implementors list of every interface it implements
1548   for (int i = local_interfaces()->length() - 1; i >= 0; i--) {
1549     assert(local_interfaces()->at(i)->is_klass(), "must be a klass");
1550     InstanceKlass* interf = local_interfaces()->at(i);
1551     assert(interf->is_interface(), "expected interface");
1552     interf->add_implementor(this);
1553   }
1554 }
1555 
1556 bool InstanceKlass::can_be_primary_super_slow() const {
1557   if (is_interface())
1558     return false;
1559   else
1560     return Klass::can_be_primary_super_slow();
1561 }
1562 
1563 GrowableArray<Klass*>* InstanceKlass::compute_secondary_supers(int num_extra_slots,
1564                                                                Array<InstanceKlass*>* transitive_interfaces) {
1565   // The secondaries are the implemented interfaces.
1566   // We need the cast because Array<Klass*> is NOT a supertype of Array<InstanceKlass*>,
1567   // (but it's safe to do here because we won't write into _secondary_supers from this point on).
1568   Array<Klass*>* interfaces = (Array<Klass*>*)(address)transitive_interfaces;
1569   int num_secondaries = num_extra_slots + interfaces->length();
1570   if (num_secondaries == 0) {
1571     // Must share this for correct bootstrapping!
1572     set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
1573     return nullptr;
1574   } else if (num_extra_slots == 0 && interfaces->length() <= 1) {
1575     // We will reuse the transitive interfaces list if we're certain
1576     // it's in hash order.
1577     uintx bitmap = compute_secondary_supers_bitmap(interfaces);
1578     set_secondary_supers(interfaces, bitmap);
1579     return nullptr;
1580   }
1581   // Copy transitive interfaces to a temporary growable array to be constructed
1582   // into the secondary super list with extra slots.
1583   GrowableArray<Klass*>* secondaries = new GrowableArray<Klass*>(interfaces->length());
1584   for (int i = 0; i < interfaces->length(); i++) {
1585     secondaries->push(interfaces->at(i));
1586   }
1587   return secondaries;
1588 }
1589 
1590 bool InstanceKlass::implements_interface(Klass* k) const {
1591   if (this == k) return true;
1592   assert(k->is_interface(), "should be an interface class");
1593   for (int i = 0; i < transitive_interfaces()->length(); i++) {
1594     if (transitive_interfaces()->at(i) == k) {
1595       return true;
1596     }
1597   }
1598   return false;
1599 }
1600 
1601 bool InstanceKlass::is_same_or_direct_interface(Klass *k) const {
1602   // Verify direct super interface
1603   if (this == k) return true;
1604   assert(k->is_interface(), "should be an interface class");
1605   for (int i = 0; i < local_interfaces()->length(); i++) {
1606     if (local_interfaces()->at(i) == k) {
1607       return true;
1608     }
1609   }
1610   return false;
1611 }
1612 
1613 instanceOop InstanceKlass::register_finalizer(instanceOop i, TRAPS) {
1614   if (TraceFinalizerRegistration) {
1615     tty->print("Registered ");
1616     i->print_value_on(tty);
1617     tty->print_cr(" (" PTR_FORMAT ") as finalizable", p2i(i));
1618   }
1619   instanceHandle h_i(THREAD, i);
1620   // Pass the handle as argument, JavaCalls::call expects oop as jobjects
1621   JavaValue result(T_VOID);
1622   JavaCallArguments args(h_i);
1623   methodHandle mh(THREAD, Universe::finalizer_register_method());
1624   JavaCalls::call(&result, mh, &args, CHECK_NULL);
1625   MANAGEMENT_ONLY(FinalizerService::on_register(h_i(), THREAD);)
1626   return h_i();
1627 }
1628 
1629 instanceOop InstanceKlass::allocate_instance(TRAPS) {
1630   assert(!is_abstract() && !is_interface(), "Should not create this object");
1631   size_t size = size_helper();  // Query before forming handle.
1632   return (instanceOop)Universe::heap()->obj_allocate(this, size, CHECK_NULL);
1633 }
1634 
1635 instanceOop InstanceKlass::allocate_instance(oop java_class, TRAPS) {
1636   Klass* k = java_lang_Class::as_Klass(java_class);
1637   if (k == nullptr) {
1638     ResourceMark rm(THREAD);
1639     THROW_(vmSymbols::java_lang_InstantiationException(), nullptr);
1640   }
1641   InstanceKlass* ik = cast(k);
1642   ik->check_valid_for_instantiation(false, CHECK_NULL);
1643   ik->initialize(CHECK_NULL);
1644   return ik->allocate_instance(THREAD);
1645 }
1646 
1647 instanceHandle InstanceKlass::allocate_instance_handle(TRAPS) {
1648   return instanceHandle(THREAD, allocate_instance(THREAD));
1649 }
1650 
1651 void InstanceKlass::check_valid_for_instantiation(bool throwError, TRAPS) {
1652   if (is_interface() || is_abstract()) {
1653     ResourceMark rm(THREAD);
1654     THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
1655               : vmSymbols::java_lang_InstantiationException(), external_name());
1656   }
1657   if (this == vmClasses::Class_klass()) {
1658     ResourceMark rm(THREAD);
1659     THROW_MSG(throwError ? vmSymbols::java_lang_IllegalAccessError()
1660               : vmSymbols::java_lang_IllegalAccessException(), external_name());
1661   }
1662 }
1663 
1664 ArrayKlass* InstanceKlass::array_klass(int n, TRAPS) {
1665   // Need load-acquire for lock-free read
1666   if (array_klasses_acquire() == nullptr) {
1667 
1668     // Recursively lock array allocation
1669     RecursiveLocker rl(MultiArray_lock, THREAD);
1670 
1671     // Check if another thread created the array klass while we were waiting for the lock.
1672     if (array_klasses() == nullptr) {
1673       ObjArrayKlass* k = ObjArrayKlass::allocate_objArray_klass(class_loader_data(), 1, this, CHECK_NULL);
1674       // use 'release' to pair with lock-free load
1675       release_set_array_klasses(k);
1676     }
1677   }
1678 
1679   // array_klasses() will always be set at this point
1680   ObjArrayKlass* ak = array_klasses();
1681   assert(ak != nullptr, "should be set");
1682   return ak->array_klass(n, THREAD);
1683 }
1684 
1685 ArrayKlass* InstanceKlass::array_klass_or_null(int n) {
1686   // Need load-acquire for lock-free read
1687   ObjArrayKlass* oak = array_klasses_acquire();
1688   if (oak == nullptr) {
1689     return nullptr;
1690   } else {
1691     return oak->array_klass_or_null(n);
1692   }
1693 }
1694 
1695 ArrayKlass* InstanceKlass::array_klass(TRAPS) {
1696   return array_klass(1, THREAD);
1697 }
1698 
1699 ArrayKlass* InstanceKlass::array_klass_or_null() {
1700   return array_klass_or_null(1);
1701 }
1702 
1703 static int call_class_initializer_counter = 0;   // for debugging
1704 
1705 Method* InstanceKlass::class_initializer() const {
1706   Method* clinit = find_method(
1707       vmSymbols::class_initializer_name(), vmSymbols::void_method_signature());
1708   if (clinit != nullptr && clinit->has_valid_initializer_flags()) {
1709     return clinit;
1710   }
1711   return nullptr;
1712 }
1713 
1714 void InstanceKlass::call_class_initializer(TRAPS) {
1715   if (ReplayCompiles &&
1716       (ReplaySuppressInitializers == 1 ||
1717        (ReplaySuppressInitializers >= 2 && class_loader() != nullptr))) {
1718     // Hide the existence of the initializer for the purpose of replaying the compile
1719     return;
1720   }
1721 
1722 #if INCLUDE_CDS
1723   // This is needed to ensure the consistency of the archived heap objects.
1724   if (has_aot_initialized_mirror() && CDSConfig::is_loading_heap()) {
1725     AOTClassInitializer::call_runtime_setup(THREAD, this);
1726     return;
1727   } else if (has_archived_enum_objs()) {
1728     assert(in_aot_cache(), "must be");
1729     bool initialized = CDSEnumKlass::initialize_enum_klass(this, CHECK);
1730     if (initialized) {
1731       return;
1732     }
1733   }
1734 #endif
1735 
1736   methodHandle h_method(THREAD, class_initializer());
1737   assert(!is_initialized(), "we cannot initialize twice");
1738   LogTarget(Info, class, init) lt;
1739   if (lt.is_enabled()) {
1740     ResourceMark rm(THREAD);
1741     LogStream ls(lt);
1742     ls.print("%d Initializing ", call_class_initializer_counter++);
1743     name()->print_value_on(&ls);
1744     ls.print_cr("%s (" PTR_FORMAT ") by thread \"%s\"",
1745                 h_method() == nullptr ? "(no method)" : "", p2i(this),
1746                 THREAD->name());
1747   }
1748   if (h_method() != nullptr) {
1749     ThreadInClassInitializer ticl(THREAD, this); // Track class being initialized
1750     JavaCallArguments args; // No arguments
1751     JavaValue result(T_VOID);
1752     JavaCalls::call(&result, h_method, &args, CHECK); // Static call (no args)
1753   }
1754 }
1755 
1756 // If a class that implements this interface is initialized, is the JVM required
1757 // to first execute a <clinit> method declared in this interface,
1758 // or (if also_check_supers==true) any of the super types of this interface?
1759 //
1760 // JVMS 5.5. Initialization, step 7: Next, if C is a class rather than
1761 // an interface, then let SC be its superclass and let SI1, ..., SIn
1762 // be all superinterfaces of C (whether direct or indirect) that
1763 // declare at least one non-abstract, non-static method.
1764 //
1765 // So when an interface is initialized, it does not look at its
1766 // supers. But a proper class will ensure that all of its supers have
1767 // run their <clinit> methods, except that it disregards interfaces
1768 // that lack a non-static concrete method (i.e., a default method).
1769 // Therefore, you should probably call this method only when the
1770 // current class is a super of some proper class, not an interface.
1771 bool InstanceKlass::interface_needs_clinit_execution_as_super(bool also_check_supers) const {
1772   assert(is_interface(), "must be");
1773 
1774   if (!has_nonstatic_concrete_methods()) {
1775     // quick check: no nonstatic concrete methods are declared by this or any super interfaces
1776     return false;
1777   }
1778 
1779   // JVMS 5.5. Initialization
1780   // ...If C is an interface that declares a non-abstract,
1781   // non-static method, the initialization of a class that
1782   // implements C directly or indirectly.
1783   if (declares_nonstatic_concrete_methods() && class_initializer() != nullptr) {
1784     return true;
1785   }
1786   if (also_check_supers) {
1787     Array<InstanceKlass*>* all_ifs = transitive_interfaces();
1788     for (int i = 0; i < all_ifs->length(); ++i) {
1789       InstanceKlass* super_intf = all_ifs->at(i);
1790       if (super_intf->declares_nonstatic_concrete_methods() && super_intf->class_initializer() != nullptr) {
1791         return true;
1792       }
1793     }
1794   }
1795   return false;
1796 }
1797 
1798 void InstanceKlass::mask_for(const methodHandle& method, int bci,
1799   InterpreterOopMap* entry_for) {
1800   // Lazily create the _oop_map_cache at first request.
1801   // Load_acquire is needed to safely get instance published with CAS by another thread.
1802   OopMapCache* oop_map_cache = AtomicAccess::load_acquire(&_oop_map_cache);
1803   if (oop_map_cache == nullptr) {
1804     // Try to install new instance atomically.
1805     oop_map_cache = new OopMapCache();
1806     OopMapCache* other = AtomicAccess::cmpxchg(&_oop_map_cache, (OopMapCache*)nullptr, oop_map_cache);
1807     if (other != nullptr) {
1808       // Someone else managed to install before us, ditch local copy and use the existing one.
1809       delete oop_map_cache;
1810       oop_map_cache = other;
1811     }
1812   }
1813   // _oop_map_cache is constant after init; lookup below does its own locking.
1814   oop_map_cache->lookup(method, bci, entry_for);
1815 }
1816 
1817 bool InstanceKlass::contains_field_offset(int offset) {
1818   fieldDescriptor fd;
1819   return find_field_from_offset(offset, false, &fd);
1820 }
1821 
1822 FieldInfo InstanceKlass::field(int index) const {
1823   for (AllFieldStream fs(this); !fs.done(); fs.next()) {
1824     if (fs.index() == index) {
1825       return fs.to_FieldInfo();
1826     }
1827   }
1828   fatal("Field not found");
1829   return FieldInfo();
1830 }
1831 
1832 bool InstanceKlass::find_local_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
1833   JavaFieldStream fs(this);
1834   if (fs.lookup(name, sig)) {
1835     assert(fs.name() == name, "name must match");
1836     assert(fs.signature() == sig, "signature must match");
1837     fd->reinitialize(const_cast<InstanceKlass*>(this), fs.to_FieldInfo());
1838     return true;
1839   }
1840   return false;
1841 }
1842 
1843 
1844 Klass* InstanceKlass::find_interface_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
1845   const int n = local_interfaces()->length();
1846   for (int i = 0; i < n; i++) {
1847     InstanceKlass* intf1 = local_interfaces()->at(i);
1848     assert(intf1->is_interface(), "just checking type");
1849     // search for field in current interface
1850     if (intf1->find_local_field(name, sig, fd)) {
1851       assert(fd->is_static(), "interface field must be static");
1852       return intf1;
1853     }
1854     // search for field in direct superinterfaces
1855     Klass* intf2 = intf1->find_interface_field(name, sig, fd);
1856     if (intf2 != nullptr) return intf2;
1857   }
1858   // otherwise field lookup fails
1859   return nullptr;
1860 }
1861 
1862 
1863 Klass* InstanceKlass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
1864   // search order according to newest JVM spec (5.4.3.2, p.167).
1865   // 1) search for field in current klass
1866   if (find_local_field(name, sig, fd)) {
1867     return const_cast<InstanceKlass*>(this);
1868   }
1869   // 2) search for field recursively in direct superinterfaces
1870   { Klass* intf = find_interface_field(name, sig, fd);
1871     if (intf != nullptr) return intf;
1872   }
1873   // 3) apply field lookup recursively if superclass exists
1874   { InstanceKlass* supr = super();
1875     if (supr != nullptr) return supr->find_field(name, sig, fd);
1876   }
1877   // 4) otherwise field lookup fails
1878   return nullptr;
1879 }
1880 
1881 
1882 Klass* InstanceKlass::find_field(Symbol* name, Symbol* sig, bool is_static, fieldDescriptor* fd) const {
1883   // search order according to newest JVM spec (5.4.3.2, p.167).
1884   // 1) search for field in current klass
1885   if (find_local_field(name, sig, fd)) {
1886     if (fd->is_static() == is_static) return const_cast<InstanceKlass*>(this);
1887   }
1888   // 2) search for field recursively in direct superinterfaces
1889   if (is_static) {
1890     Klass* intf = find_interface_field(name, sig, fd);
1891     if (intf != nullptr) return intf;
1892   }
1893   // 3) apply field lookup recursively if superclass exists
1894   { InstanceKlass* supr = super();
1895     if (supr != nullptr) return supr->find_field(name, sig, is_static, fd);
1896   }
1897   // 4) otherwise field lookup fails
1898   return nullptr;
1899 }
1900 
1901 
1902 bool InstanceKlass::find_local_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const {
1903   for (JavaFieldStream fs(this); !fs.done(); fs.next()) {
1904     if (fs.offset() == offset) {
1905       fd->reinitialize(const_cast<InstanceKlass*>(this), fs.to_FieldInfo());
1906       if (fd->is_static() == is_static) return true;
1907     }
1908   }
1909   return false;
1910 }
1911 
1912 
1913 bool InstanceKlass::find_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const {
1914   const InstanceKlass* klass = this;
1915   while (klass != nullptr) {
1916     if (klass->find_local_field_from_offset(offset, is_static, fd)) {
1917       return true;
1918     }
1919     klass = klass->super();
1920   }
1921   return false;
1922 }
1923 
1924 
1925 void InstanceKlass::methods_do(void f(Method* method)) {
1926   // Methods aren't stable until they are loaded.  This can be read outside
1927   // a lock through the ClassLoaderData for profiling
1928   // Redefined scratch classes are on the list and need to be cleaned
1929   if (!is_loaded() && !is_scratch_class()) {
1930     return;
1931   }
1932 
1933   int len = methods()->length();
1934   for (int index = 0; index < len; index++) {
1935     Method* m = methods()->at(index);
1936     assert(m->is_method(), "must be method");
1937     f(m);
1938   }
1939 }
1940 
1941 
1942 void InstanceKlass::do_local_static_fields(FieldClosure* cl) {
1943   for (JavaFieldStream fs(this); !fs.done(); fs.next()) {
1944     if (fs.access_flags().is_static()) {
1945       fieldDescriptor& fd = fs.field_descriptor();
1946       cl->do_field(&fd);
1947     }
1948   }
1949 }
1950 
1951 
1952 void InstanceKlass::do_local_static_fields(void f(fieldDescriptor*, Handle, TRAPS), Handle mirror, TRAPS) {
1953   for (JavaFieldStream fs(this); !fs.done(); fs.next()) {
1954     if (fs.access_flags().is_static()) {
1955       fieldDescriptor& fd = fs.field_descriptor();
1956       f(&fd, mirror, CHECK);
1957     }
1958   }
1959 }
1960 
1961 void InstanceKlass::do_nonstatic_fields(FieldClosure* cl) {
1962   InstanceKlass* super = this->super();
1963   if (super != nullptr) {
1964     super->do_nonstatic_fields(cl);
1965   }
1966   for (JavaFieldStream fs(this); !fs.done(); fs.next()) {
1967     fieldDescriptor& fd = fs.field_descriptor();
1968     if (!fd.is_static()) {
1969       cl->do_field(&fd);
1970     }
1971   }
1972 }
1973 
1974 static int compare_fields_by_offset(FieldInfo* a, FieldInfo* b) {
1975   return a->offset() - b->offset();
1976 }
1977 
1978 void InstanceKlass::print_nonstatic_fields(FieldClosure* cl) {
1979   InstanceKlass* super = this->super();
1980   if (super != nullptr) {
1981     super->print_nonstatic_fields(cl);
1982   }
1983   ResourceMark rm;
1984   // In DebugInfo nonstatic fields are sorted by offset.
1985   GrowableArray<FieldInfo> fields_sorted;
1986   for (AllFieldStream fs(this); !fs.done(); fs.next()) {
1987     if (!fs.access_flags().is_static()) {
1988       fields_sorted.push(fs.to_FieldInfo());
1989     }
1990   }
1991   int length = fields_sorted.length();
1992   if (length > 0) {
1993     fields_sorted.sort(compare_fields_by_offset);
1994     fieldDescriptor fd;
1995     for (int i = 0; i < length; i++) {
1996       fd.reinitialize(this, fields_sorted.at(i));
1997       assert(!fd.is_static() && fd.offset() == checked_cast<int>(fields_sorted.at(i).offset()), "only nonstatic fields");
1998       cl->do_field(&fd);
1999     }
2000   }
2001 }
2002 
2003 #ifdef ASSERT
2004 static int linear_search(const Array<Method*>* methods,
2005                          const Symbol* name,
2006                          const Symbol* signature) {
2007   const int len = methods->length();
2008   for (int index = 0; index < len; index++) {
2009     const Method* const m = methods->at(index);
2010     assert(m->is_method(), "must be method");
2011     if (m->signature() == signature && m->name() == name) {
2012        return index;
2013     }
2014   }
2015   return -1;
2016 }
2017 #endif
2018 
2019 bool InstanceKlass::_disable_method_binary_search = false;
2020 
2021 NOINLINE int linear_search(const Array<Method*>* methods, const Symbol* name) {
2022   int len = methods->length();
2023   int l = 0;
2024   int h = len - 1;
2025   while (l <= h) {
2026     Method* m = methods->at(l);
2027     if (m->name() == name) {
2028       return l;
2029     }
2030     l++;
2031   }
2032   return -1;
2033 }
2034 
2035 inline int InstanceKlass::quick_search(const Array<Method*>* methods, const Symbol* name) {
2036   if (_disable_method_binary_search) {
2037     assert(CDSConfig::is_dumping_dynamic_archive(), "must be");
2038     // At the final stage of dynamic dumping, the methods array may not be sorted
2039     // by ascending addresses of their names, so we can't use binary search anymore.
2040     // However, methods with the same name are still laid out consecutively inside the
2041     // methods array, so let's look for the first one that matches.
2042     return linear_search(methods, name);
2043   }
2044 
2045   int len = methods->length();
2046   int l = 0;
2047   int h = len - 1;
2048 
2049   // methods are sorted by ascending addresses of their names, so do binary search
2050   while (l <= h) {
2051     int mid = (l + h) >> 1;
2052     Method* m = methods->at(mid);
2053     assert(m->is_method(), "must be method");
2054     int res = m->name()->fast_compare(name);
2055     if (res == 0) {
2056       return mid;
2057     } else if (res < 0) {
2058       l = mid + 1;
2059     } else {
2060       h = mid - 1;
2061     }
2062   }
2063   return -1;
2064 }
2065 
2066 // find_method looks up the name/signature in the local methods array
2067 Method* InstanceKlass::find_method(const Symbol* name,
2068                                    const Symbol* signature) const {
2069   return find_method_impl(name, signature,
2070                           OverpassLookupMode::find,
2071                           StaticLookupMode::find,
2072                           PrivateLookupMode::find);
2073 }
2074 
2075 Method* InstanceKlass::find_method_impl(const Symbol* name,
2076                                         const Symbol* signature,
2077                                         OverpassLookupMode overpass_mode,
2078                                         StaticLookupMode static_mode,
2079                                         PrivateLookupMode private_mode) const {
2080   return InstanceKlass::find_method_impl(methods(),
2081                                          name,
2082                                          signature,
2083                                          overpass_mode,
2084                                          static_mode,
2085                                          private_mode);
2086 }
2087 
2088 // find_instance_method looks up the name/signature in the local methods array
2089 // and skips over static methods
2090 Method* InstanceKlass::find_instance_method(const Array<Method*>* methods,
2091                                             const Symbol* name,
2092                                             const Symbol* signature,
2093                                             PrivateLookupMode private_mode) {
2094   Method* const meth = InstanceKlass::find_method_impl(methods,
2095                                                  name,
2096                                                  signature,
2097                                                  OverpassLookupMode::find,
2098                                                  StaticLookupMode::skip,
2099                                                  private_mode);
2100   assert(((meth == nullptr) || !meth->is_static()),
2101     "find_instance_method should have skipped statics");
2102   return meth;
2103 }
2104 
2105 // find_instance_method looks up the name/signature in the local methods array
2106 // and skips over static methods
2107 Method* InstanceKlass::find_instance_method(const Symbol* name,
2108                                             const Symbol* signature,
2109                                             PrivateLookupMode private_mode) const {
2110   return InstanceKlass::find_instance_method(methods(), name, signature, private_mode);
2111 }
2112 
2113 // Find looks up the name/signature in the local methods array
2114 // and filters on the overpass, static and private flags
2115 // This returns the first one found
2116 // note that the local methods array can have up to one overpass, one static
2117 // and one instance (private or not) with the same name/signature
2118 Method* InstanceKlass::find_local_method(const Symbol* name,
2119                                          const Symbol* signature,
2120                                          OverpassLookupMode overpass_mode,
2121                                          StaticLookupMode static_mode,
2122                                          PrivateLookupMode private_mode) const {
2123   return InstanceKlass::find_method_impl(methods(),
2124                                          name,
2125                                          signature,
2126                                          overpass_mode,
2127                                          static_mode,
2128                                          private_mode);
2129 }
2130 
2131 // Find looks up the name/signature in the local methods array
2132 // and filters on the overpass, static and private flags
2133 // This returns the first one found
2134 // note that the local methods array can have up to one overpass, one static
2135 // and one instance (private or not) with the same name/signature
2136 Method* InstanceKlass::find_local_method(const Array<Method*>* methods,
2137                                          const Symbol* name,
2138                                          const Symbol* signature,
2139                                          OverpassLookupMode overpass_mode,
2140                                          StaticLookupMode static_mode,
2141                                          PrivateLookupMode private_mode) {
2142   return InstanceKlass::find_method_impl(methods,
2143                                          name,
2144                                          signature,
2145                                          overpass_mode,
2146                                          static_mode,
2147                                          private_mode);
2148 }
2149 
2150 Method* InstanceKlass::find_method(const Array<Method*>* methods,
2151                                    const Symbol* name,
2152                                    const Symbol* signature) {
2153   return InstanceKlass::find_method_impl(methods,
2154                                          name,
2155                                          signature,
2156                                          OverpassLookupMode::find,
2157                                          StaticLookupMode::find,
2158                                          PrivateLookupMode::find);
2159 }
2160 
2161 Method* InstanceKlass::find_method_impl(const Array<Method*>* methods,
2162                                         const Symbol* name,
2163                                         const Symbol* signature,
2164                                         OverpassLookupMode overpass_mode,
2165                                         StaticLookupMode static_mode,
2166                                         PrivateLookupMode private_mode) {
2167   int hit = find_method_index(methods, name, signature, overpass_mode, static_mode, private_mode);
2168   return hit >= 0 ? methods->at(hit): nullptr;
2169 }
2170 
2171 // true if method matches signature and conforms to skipping_X conditions.
2172 static bool method_matches(const Method* m,
2173                            const Symbol* signature,
2174                            bool skipping_overpass,
2175                            bool skipping_static,
2176                            bool skipping_private) {
2177   return ((m->signature() == signature) &&
2178     (!skipping_overpass || !m->is_overpass()) &&
2179     (!skipping_static || !m->is_static()) &&
2180     (!skipping_private || !m->is_private()));
2181 }
2182 
2183 // Used directly for default_methods to find the index into the
2184 // default_vtable_indices, and indirectly by find_method
2185 // find_method_index looks in the local methods array to return the index
2186 // of the matching name/signature. If, overpass methods are being ignored,
2187 // the search continues to find a potential non-overpass match.  This capability
2188 // is important during method resolution to prefer a static method, for example,
2189 // over an overpass method.
2190 // There is the possibility in any _method's array to have the same name/signature
2191 // for a static method, an overpass method and a local instance method
2192 // To correctly catch a given method, the search criteria may need
2193 // to explicitly skip the other two. For local instance methods, it
2194 // is often necessary to skip private methods
2195 int InstanceKlass::find_method_index(const Array<Method*>* methods,
2196                                      const Symbol* name,
2197                                      const Symbol* signature,
2198                                      OverpassLookupMode overpass_mode,
2199                                      StaticLookupMode static_mode,
2200                                      PrivateLookupMode private_mode) {
2201   const bool skipping_overpass = (overpass_mode == OverpassLookupMode::skip);
2202   const bool skipping_static = (static_mode == StaticLookupMode::skip);
2203   const bool skipping_private = (private_mode == PrivateLookupMode::skip);
2204   const int hit = quick_search(methods, name);
2205   if (hit != -1) {
2206     const Method* const m = methods->at(hit);
2207 
2208     // Do linear search to find matching signature.  First, quick check
2209     // for common case, ignoring overpasses if requested.
2210     if (method_matches(m, signature, skipping_overpass, skipping_static, skipping_private)) {
2211       return hit;
2212     }
2213 
2214     // search downwards through overloaded methods
2215     int i;
2216     for (i = hit - 1; i >= 0; --i) {
2217         const Method* const m = methods->at(i);
2218         assert(m->is_method(), "must be method");
2219         if (m->name() != name) {
2220           break;
2221         }
2222         if (method_matches(m, signature, skipping_overpass, skipping_static, skipping_private)) {
2223           return i;
2224         }
2225     }
2226     // search upwards
2227     for (i = hit + 1; i < methods->length(); ++i) {
2228         const Method* const m = methods->at(i);
2229         assert(m->is_method(), "must be method");
2230         if (m->name() != name) {
2231           break;
2232         }
2233         if (method_matches(m, signature, skipping_overpass, skipping_static, skipping_private)) {
2234           return i;
2235         }
2236     }
2237     // not found
2238 #ifdef ASSERT
2239     const int index = (skipping_overpass || skipping_static || skipping_private) ? -1 :
2240       linear_search(methods, name, signature);
2241     assert(-1 == index, "binary search should have found entry %d", index);
2242 #endif
2243   }
2244   return -1;
2245 }
2246 
2247 int InstanceKlass::find_method_by_name(const Symbol* name, int* end) const {
2248   return find_method_by_name(methods(), name, end);
2249 }
2250 
2251 int InstanceKlass::find_method_by_name(const Array<Method*>* methods,
2252                                        const Symbol* name,
2253                                        int* end_ptr) {
2254   assert(end_ptr != nullptr, "just checking");
2255   int start = quick_search(methods, name);
2256   int end = start + 1;
2257   if (start != -1) {
2258     while (start - 1 >= 0 && (methods->at(start - 1))->name() == name) --start;
2259     while (end < methods->length() && (methods->at(end))->name() == name) ++end;
2260     *end_ptr = end;
2261     return start;
2262   }
2263   return -1;
2264 }
2265 
2266 // uncached_lookup_method searches both the local class methods array and all
2267 // superclasses methods arrays, skipping any overpass methods in superclasses,
2268 // and possibly skipping private methods.
2269 Method* InstanceKlass::uncached_lookup_method(const Symbol* name,
2270                                               const Symbol* signature,
2271                                               OverpassLookupMode overpass_mode,
2272                                               PrivateLookupMode private_mode) const {
2273   OverpassLookupMode overpass_local_mode = overpass_mode;
2274   const InstanceKlass* klass = this;
2275   while (klass != nullptr) {
2276     Method* const method = klass->find_method_impl(name,
2277                                                    signature,
2278                                                    overpass_local_mode,
2279                                                    StaticLookupMode::find,
2280                                                    private_mode);
2281     if (method != nullptr) {
2282       return method;
2283     }
2284     klass = klass->super();
2285     overpass_local_mode = OverpassLookupMode::skip;   // Always ignore overpass methods in superclasses
2286   }
2287   return nullptr;
2288 }
2289 
2290 #ifdef ASSERT
2291 // search through class hierarchy and return true if this class or
2292 // one of the superclasses was redefined
2293 bool InstanceKlass::has_redefined_this_or_super() const {
2294   const InstanceKlass* klass = this;
2295   while (klass != nullptr) {
2296     if (klass->has_been_redefined()) {
2297       return true;
2298     }
2299     klass = klass->super();
2300   }
2301   return false;
2302 }
2303 #endif
2304 
2305 // lookup a method in the default methods list then in all transitive interfaces
2306 // Do NOT return private or static methods
2307 Method* InstanceKlass::lookup_method_in_ordered_interfaces(Symbol* name,
2308                                                          Symbol* signature) const {
2309   Method* m = nullptr;
2310   if (default_methods() != nullptr) {
2311     m = find_method(default_methods(), name, signature);
2312   }
2313   // Look up interfaces
2314   if (m == nullptr) {
2315     m = lookup_method_in_all_interfaces(name, signature, DefaultsLookupMode::find);
2316   }
2317   return m;
2318 }
2319 
2320 // lookup a method in all the interfaces that this class implements
2321 // Do NOT return private or static methods, new in JDK8 which are not externally visible
2322 // They should only be found in the initial InterfaceMethodRef
2323 Method* InstanceKlass::lookup_method_in_all_interfaces(Symbol* name,
2324                                                        Symbol* signature,
2325                                                        DefaultsLookupMode defaults_mode) const {
2326   Array<InstanceKlass*>* all_ifs = transitive_interfaces();
2327   int num_ifs = all_ifs->length();
2328   InstanceKlass *ik = nullptr;
2329   for (int i = 0; i < num_ifs; i++) {
2330     ik = all_ifs->at(i);
2331     Method* m = ik->lookup_method(name, signature);
2332     if (m != nullptr && m->is_public() && !m->is_static() &&
2333         ((defaults_mode != DefaultsLookupMode::skip) || !m->is_default_method())) {
2334       return m;
2335     }
2336   }
2337   return nullptr;
2338 }
2339 
2340 PrintClassClosure::PrintClassClosure(outputStream* st, bool verbose)
2341   :_st(st), _verbose(verbose) {
2342   ResourceMark rm;
2343   _st->print("%-18s  ", "KlassAddr");
2344   _st->print("%-4s  ", "Size");
2345   _st->print("%-20s  ", "State");
2346   _st->print("%-7s  ", "Flags");
2347   _st->print("%-5s  ", "ClassName");
2348   _st->cr();
2349 }
2350 
2351 void PrintClassClosure::do_klass(Klass* k)  {
2352   ResourceMark rm;
2353   // klass pointer
2354   _st->print(PTR_FORMAT "  ", p2i(k));
2355   // klass size
2356   _st->print("%4d  ", k->size());
2357   // initialization state
2358   if (k->is_instance_klass()) {
2359     _st->print("%-20s  ",InstanceKlass::cast(k)->init_state_name());
2360   } else {
2361     _st->print("%-20s  ","");
2362   }
2363   // misc flags(Changes should synced with ClassesDCmd::ClassesDCmd help doc)
2364   char buf[10];
2365   int i = 0;
2366   if (k->has_finalizer()) buf[i++] = 'F';
2367   if (k->is_instance_klass()) {
2368     InstanceKlass* ik = InstanceKlass::cast(k);
2369     if (ik->has_final_method()) buf[i++] = 'f';
2370     if (ik->is_rewritten()) buf[i++] = 'W';
2371     if (ik->is_contended()) buf[i++] = 'C';
2372     if (ik->has_been_redefined()) buf[i++] = 'R';
2373     if (ik->in_aot_cache()) buf[i++] = 'S';
2374   }
2375   buf[i++] = '\0';
2376   _st->print("%-7s  ", buf);
2377   // klass name
2378   _st->print("%-5s  ", k->external_name());
2379   // end
2380   _st->cr();
2381   if (_verbose) {
2382     k->print_on(_st);
2383   }
2384 }
2385 
2386 /* jni_id_for for jfieldIds only */
2387 JNIid* InstanceKlass::jni_id_for(int offset) {
2388   MutexLocker ml(JfieldIdCreation_lock);
2389   JNIid* probe = jni_ids() == nullptr ? nullptr : jni_ids()->find(offset);
2390   if (probe == nullptr) {
2391     // Allocate new static field identifier
2392     probe = new JNIid(this, offset, jni_ids());
2393     set_jni_ids(probe);
2394   }
2395   return probe;
2396 }
2397 
2398 u2 InstanceKlass::enclosing_method_data(int offset) const {
2399   const Array<jushort>* const inner_class_list = inner_classes();
2400   if (inner_class_list == nullptr) {
2401     return 0;
2402   }
2403   const int length = inner_class_list->length();
2404   if (length % inner_class_next_offset == 0) {
2405     return 0;
2406   }
2407   const int index = length - enclosing_method_attribute_size;
2408   assert(offset < enclosing_method_attribute_size, "invalid offset");
2409   return inner_class_list->at(index + offset);
2410 }
2411 
2412 void InstanceKlass::set_enclosing_method_indices(u2 class_index,
2413                                                  u2 method_index) {
2414   Array<jushort>* inner_class_list = inner_classes();
2415   assert (inner_class_list != nullptr, "_inner_classes list is not set up");
2416   int length = inner_class_list->length();
2417   if (length % inner_class_next_offset == enclosing_method_attribute_size) {
2418     int index = length - enclosing_method_attribute_size;
2419     inner_class_list->at_put(
2420       index + enclosing_method_class_index_offset, class_index);
2421     inner_class_list->at_put(
2422       index + enclosing_method_method_index_offset, method_index);
2423   }
2424 }
2425 
2426 jmethodID InstanceKlass::update_jmethod_id(jmethodID* jmeths, Method* method, int idnum) {
2427   if (method->is_old() && !method->is_obsolete()) {
2428     // If the method passed in is old (but not obsolete), use the current version.
2429     method = method_with_idnum((int)idnum);
2430     assert(method != nullptr, "old and but not obsolete, so should exist");
2431   }
2432   jmethodID new_id = Method::make_jmethod_id(class_loader_data(), method);
2433   AtomicAccess::release_store(&jmeths[idnum + 1], new_id);
2434   return new_id;
2435 }
2436 
2437 // Allocate the jmethodID cache.
2438 static jmethodID* create_jmethod_id_cache(size_t size) {
2439   jmethodID* jmeths = NEW_C_HEAP_ARRAY(jmethodID, size + 1, mtClass);
2440   memset(jmeths, 0, (size + 1) * sizeof(jmethodID));
2441   // cache size is stored in element[0], other elements offset by one
2442   jmeths[0] = (jmethodID)size;
2443   return jmeths;
2444 }
2445 
2446 // When reading outside a lock, use this.
2447 jmethodID* InstanceKlass::methods_jmethod_ids_acquire() const {
2448   return AtomicAccess::load_acquire(&_methods_jmethod_ids);
2449 }
2450 
2451 void InstanceKlass::release_set_methods_jmethod_ids(jmethodID* jmeths) {
2452   AtomicAccess::release_store(&_methods_jmethod_ids, jmeths);
2453 }
2454 
2455 // Lookup or create a jmethodID.
2456 jmethodID InstanceKlass::get_jmethod_id(Method* method) {
2457   int idnum = method->method_idnum();
2458   jmethodID* jmeths = methods_jmethod_ids_acquire();
2459 
2460   // We use a double-check locking idiom here because this cache is
2461   // performance sensitive. In the normal system, this cache only
2462   // transitions from null to non-null which is safe because we use
2463   // release_set_methods_jmethod_ids() to advertise the new cache.
2464   // A partially constructed cache should never be seen by a racing
2465   // thread. We also use release_store() to save a new jmethodID
2466   // in the cache so a partially constructed jmethodID should never be
2467   // seen either. Cache reads of existing jmethodIDs proceed without a
2468   // lock, but cache writes of a new jmethodID requires uniqueness and
2469   // creation of the cache itself requires no leaks so a lock is
2470   // acquired in those two cases.
2471   //
2472   // If the RedefineClasses() API has been used, then this cache grows
2473   // in the redefinition safepoint.
2474 
2475   if (jmeths == nullptr) {
2476     MutexLocker ml(JmethodIdCreation_lock, Mutex::_no_safepoint_check_flag);
2477     jmeths = _methods_jmethod_ids;
2478     // Still null?
2479     if (jmeths == nullptr) {
2480       size_t size = idnum_allocated_count();
2481       assert(size > (size_t)idnum, "should already have space");
2482       jmeths = create_jmethod_id_cache(size);
2483       jmethodID new_id = update_jmethod_id(jmeths, method, idnum);
2484 
2485       // publish jmeths
2486       release_set_methods_jmethod_ids(jmeths);
2487       return new_id;
2488     }
2489   }
2490 
2491   jmethodID id = AtomicAccess::load_acquire(&jmeths[idnum + 1]);
2492   if (id == nullptr) {
2493     MutexLocker ml(JmethodIdCreation_lock, Mutex::_no_safepoint_check_flag);
2494     id = jmeths[idnum + 1];
2495     // Still null?
2496     if (id == nullptr) {
2497       return update_jmethod_id(jmeths, method, idnum);
2498     }
2499   }
2500   return id;
2501 }
2502 
2503 void InstanceKlass::update_methods_jmethod_cache() {
2504   assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
2505   jmethodID* cache = _methods_jmethod_ids;
2506   if (cache != nullptr) {
2507     size_t size = idnum_allocated_count();
2508     size_t old_size = (size_t)cache[0];
2509     if (old_size < size + 1) {
2510       // Allocate a larger one and copy entries to the new one.
2511       // They've already been updated to point to new methods where applicable (i.e., not obsolete).
2512       jmethodID* new_cache = create_jmethod_id_cache(size);
2513 
2514       for (int i = 1; i <= (int)old_size; i++) {
2515         new_cache[i] = cache[i];
2516       }
2517       _methods_jmethod_ids = new_cache;
2518       FREE_C_HEAP_ARRAY(jmethodID, cache);
2519     }
2520   }
2521 }
2522 
2523 // Make a jmethodID for all methods in this class.  This makes getting all method
2524 // ids much, much faster with classes with more than 8
2525 // methods, and has a *substantial* effect on performance with jvmti
2526 // code that loads all jmethodIDs for all classes.
2527 void InstanceKlass::make_methods_jmethod_ids() {
2528   MutexLocker ml(JmethodIdCreation_lock, Mutex::_no_safepoint_check_flag);
2529   jmethodID* jmeths = _methods_jmethod_ids;
2530   if (jmeths == nullptr) {
2531     jmeths = create_jmethod_id_cache(idnum_allocated_count());
2532     release_set_methods_jmethod_ids(jmeths);
2533   }
2534 
2535   int length = methods()->length();
2536   for (int index = 0; index < length; index++) {
2537     Method* m = methods()->at(index);
2538     int idnum = m->method_idnum();
2539     assert(!m->is_old(), "should not have old methods or I'm confused");
2540     jmethodID id = AtomicAccess::load_acquire(&jmeths[idnum + 1]);
2541     if (!m->is_overpass() &&  // skip overpasses
2542         id == nullptr) {
2543       id = Method::make_jmethod_id(class_loader_data(), m);
2544       AtomicAccess::release_store(&jmeths[idnum + 1], id);
2545     }
2546   }
2547 }
2548 
2549 // Lookup a jmethodID, null if not found.  Do no blocking, no allocations, no handles
2550 jmethodID InstanceKlass::jmethod_id_or_null(Method* method) {
2551   int idnum = method->method_idnum();
2552   jmethodID* jmeths = methods_jmethod_ids_acquire();
2553   return (jmeths != nullptr) ? jmeths[idnum + 1] : nullptr;
2554 }
2555 
2556 inline DependencyContext InstanceKlass::dependencies() {
2557   DependencyContext dep_context(&_dep_context, &_dep_context_last_cleaned);
2558   return dep_context;
2559 }
2560 
2561 void InstanceKlass::mark_dependent_nmethods(DeoptimizationScope* deopt_scope, KlassDepChange& changes) {
2562   dependencies().mark_dependent_nmethods(deopt_scope, changes);
2563 }
2564 
2565 void InstanceKlass::add_dependent_nmethod(nmethod* nm) {
2566   assert_lock_strong(CodeCache_lock);
2567   dependencies().add_dependent_nmethod(nm);
2568 }
2569 
2570 void InstanceKlass::clean_dependency_context() {
2571   dependencies().clean_unloading_dependents();
2572 }
2573 
2574 #ifndef PRODUCT
2575 void InstanceKlass::print_dependent_nmethods(bool verbose) {
2576   dependencies().print_dependent_nmethods(verbose);
2577 }
2578 
2579 bool InstanceKlass::is_dependent_nmethod(nmethod* nm) {
2580   return dependencies().is_dependent_nmethod(nm);
2581 }
2582 #endif //PRODUCT
2583 
2584 void InstanceKlass::clean_weak_instanceklass_links() {
2585   clean_implementors_list();
2586   clean_method_data();
2587 }
2588 
2589 void InstanceKlass::clean_implementors_list() {
2590   assert(is_loader_alive(), "this klass should be live");
2591   if (is_interface()) {
2592     assert (ClassUnloading, "only called for ClassUnloading");
2593     for (;;) {
2594       // Use load_acquire due to competing with inserts
2595       InstanceKlass* volatile* iklass = adr_implementor();
2596       assert(iklass != nullptr, "Klass must not be null");
2597       InstanceKlass* impl = AtomicAccess::load_acquire(iklass);
2598       if (impl != nullptr && !impl->is_loader_alive()) {
2599         // null this field, might be an unloaded instance klass or null
2600         if (AtomicAccess::cmpxchg(iklass, impl, (InstanceKlass*)nullptr) == impl) {
2601           // Successfully unlinking implementor.
2602           if (log_is_enabled(Trace, class, unload)) {
2603             ResourceMark rm;
2604             log_trace(class, unload)("unlinking class (implementor): %s", impl->external_name());
2605           }
2606           return;
2607         }
2608       } else {
2609         return;
2610       }
2611     }
2612   }
2613 }
2614 
2615 void InstanceKlass::clean_method_data() {
2616   for (int m = 0; m < methods()->length(); m++) {
2617     MethodData* mdo = methods()->at(m)->method_data();
2618     if (mdo != nullptr) {
2619       mdo->clean_method_data(/*always_clean*/false);
2620     }
2621   }
2622 }
2623 
2624 void InstanceKlass::metaspace_pointers_do(MetaspaceClosure* it) {
2625   Klass::metaspace_pointers_do(it);
2626 
2627   if (log_is_enabled(Trace, aot)) {
2628     ResourceMark rm;
2629     log_trace(aot)("Iter(InstanceKlass): %p (%s)", this, external_name());
2630   }
2631 
2632   it->push(&_annotations);
2633   it->push((Klass**)&_array_klasses);
2634   if (!is_rewritten()) {
2635     it->push(&_constants, MetaspaceClosure::_writable);
2636   } else {
2637     it->push(&_constants);
2638   }
2639   it->push(&_inner_classes);
2640 #if INCLUDE_JVMTI
2641   it->push(&_previous_versions);
2642 #endif
2643 #if INCLUDE_CDS
2644   // For "old" classes with methods containing the jsr bytecode, the _methods array will
2645   // be rewritten during runtime (see Rewriter::rewrite_jsrs()) but they cannot be safely
2646   // checked here with ByteCodeStream. All methods that can't be verified are made writable.
2647   // The length check on the _methods is necessary because classes which don't have any
2648   // methods share the Universe::_the_empty_method_array which is in the RO region.
2649   if (_methods != nullptr && _methods->length() > 0 && !can_be_verified_at_dumptime()) {
2650     // To handle jsr bytecode, new Method* maybe stored into _methods
2651     it->push(&_methods, MetaspaceClosure::_writable);
2652   } else {
2653 #endif
2654     it->push(&_methods);
2655 #if INCLUDE_CDS
2656   }
2657 #endif
2658   it->push(&_default_methods);
2659   it->push(&_local_interfaces);
2660   it->push(&_transitive_interfaces);
2661   it->push(&_method_ordering);
2662   if (!is_rewritten()) {
2663     it->push(&_default_vtable_indices, MetaspaceClosure::_writable);
2664   } else {
2665     it->push(&_default_vtable_indices);
2666   }
2667 
2668   it->push(&_fieldinfo_stream);
2669   it->push(&_fieldinfo_search_table);
2670   // _fields_status might be written into by Rewriter::scan_method() -> fd.set_has_initialized_final_update()
2671   it->push(&_fields_status, MetaspaceClosure::_writable);
2672 
2673   if (itable_length() > 0) {
2674     itableOffsetEntry* ioe = (itableOffsetEntry*)start_of_itable();
2675     int method_table_offset_in_words = ioe->offset()/wordSize;
2676     int itable_offset_in_words = (int)(start_of_itable() - (intptr_t*)this);
2677 
2678     int nof_interfaces = (method_table_offset_in_words - itable_offset_in_words)
2679                          / itableOffsetEntry::size();
2680 
2681     for (int i = 0; i < nof_interfaces; i ++, ioe ++) {
2682       if (ioe->interface_klass() != nullptr) {
2683         it->push(ioe->interface_klass_addr());
2684         itableMethodEntry* ime = ioe->first_method_entry(this);
2685         int n = klassItable::method_count_for_interface(ioe->interface_klass());
2686         for (int index = 0; index < n; index ++) {
2687           it->push(ime[index].method_addr());
2688         }
2689       }
2690     }
2691   }
2692 
2693   it->push(&_nest_host);
2694   it->push(&_nest_members);
2695   it->push(&_permitted_subclasses);
2696   it->push(&_record_components);
2697 
2698   if (CDSConfig::is_dumping_full_module_graph() && !defined_by_other_loaders()) {
2699     it->push(&_package_entry);
2700   }
2701 }
2702 
2703 #if INCLUDE_CDS
2704 void InstanceKlass::remove_unshareable_info() {
2705 
2706   if (is_linked()) {
2707     assert(can_be_verified_at_dumptime(), "must be");
2708     // Remember this so we can avoid walking the hierarchy at runtime.
2709     set_verified_at_dump_time();
2710   }
2711 
2712   _misc_flags.set_has_init_deps_processed(false);
2713 
2714   Klass::remove_unshareable_info();
2715 
2716   if (SystemDictionaryShared::has_class_failed_verification(this)) {
2717     // Classes are attempted to link during dumping and may fail,
2718     // but these classes are still in the dictionary and class list in CLD.
2719     // If the class has failed verification, there is nothing else to remove.
2720     return;
2721   }
2722 
2723   // Reset to the 'allocated' state to prevent any premature accessing to
2724   // a shared class at runtime while the class is still being loaded and
2725   // restored. A class' init_state is set to 'loaded' at runtime when it's
2726   // being added to class hierarchy (see InstanceKlass:::add_to_hierarchy()).
2727   _init_state = allocated;
2728 
2729   { // Otherwise this needs to take out the Compile_lock.
2730     assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
2731     init_implementor();
2732   }
2733 
2734   // Call remove_unshareable_info() on other objects that belong to this class, except
2735   // for constants()->remove_unshareable_info(), which is called in a separate pass in
2736   // ArchiveBuilder::make_klasses_shareable(),
2737 
2738   for (int i = 0; i < methods()->length(); i++) {
2739     Method* m = methods()->at(i);
2740     m->remove_unshareable_info();
2741   }
2742 
2743   // do array classes also.
2744   if (array_klasses() != nullptr) {
2745     array_klasses()->remove_unshareable_info();
2746   }
2747 
2748   // These are not allocated from metaspace. They are safe to set to null.
2749   _source_debug_extension = nullptr;
2750   _dep_context = nullptr;
2751   _osr_nmethods_head = nullptr;
2752 #if INCLUDE_JVMTI
2753   _breakpoints = nullptr;
2754   _previous_versions = nullptr;
2755   _cached_class_file = nullptr;
2756   _jvmti_cached_class_field_map = nullptr;
2757 #endif
2758 
2759   _init_thread = nullptr;
2760   _methods_jmethod_ids = nullptr;
2761   _jni_ids = nullptr;
2762   _oop_map_cache = nullptr;
2763   if (CDSConfig::is_dumping_method_handles() && HeapShared::is_lambda_proxy_klass(this)) {
2764     // keep _nest_host
2765   } else {
2766     // clear _nest_host to ensure re-load at runtime
2767     _nest_host = nullptr;
2768   }
2769   init_shared_package_entry();
2770   _dep_context_last_cleaned = 0;
2771   DEBUG_ONLY(_shared_class_load_count = 0);
2772 
2773   remove_unshareable_flags();
2774 
2775   DEBUG_ONLY(FieldInfoStream::validate_search_table(_constants, _fieldinfo_stream, _fieldinfo_search_table));
2776 }
2777 
2778 void InstanceKlass::remove_unshareable_flags() {
2779   // clear all the flags/stats that shouldn't be in the archived version
2780   assert(!is_scratch_class(), "must be");
2781   assert(!has_been_redefined(), "must be");
2782 #if INCLUDE_JVMTI
2783   set_is_being_redefined(false);
2784 #endif
2785   set_has_resolved_methods(false);
2786 }
2787 
2788 void InstanceKlass::remove_java_mirror() {
2789   Klass::remove_java_mirror();
2790 
2791   // do array classes also.
2792   if (array_klasses() != nullptr) {
2793     array_klasses()->remove_java_mirror();
2794   }
2795 }
2796 
2797 void InstanceKlass::init_shared_package_entry() {
2798   assert(CDSConfig::is_dumping_archive(), "must be");
2799   if (!CDSConfig::is_dumping_full_module_graph() || defined_by_other_loaders()) {
2800     _package_entry = nullptr;
2801   }
2802 }
2803 
2804 void InstanceKlass::compute_has_loops_flag_for_methods() {
2805   Array<Method*>* methods = this->methods();
2806   for (int index = 0; index < methods->length(); ++index) {
2807     Method* m = methods->at(index);
2808     if (!m->is_overpass()) { // work around JDK-8305771
2809       m->compute_has_loops_flag();
2810     }
2811   }
2812 }
2813 
2814 void InstanceKlass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain,
2815                                              PackageEntry* pkg_entry, TRAPS) {
2816   // InstanceKlass::add_to_hierarchy() sets the init_state to loaded
2817   // before the InstanceKlass is added to the SystemDictionary. Make
2818   // sure the current state is <loaded.
2819   assert(!is_loaded(), "invalid init state");
2820   assert(!shared_loading_failed(), "Must not try to load failed class again");
2821   set_package(loader_data, pkg_entry, CHECK);
2822   Klass::restore_unshareable_info(loader_data, protection_domain, CHECK);
2823 
2824   Array<Method*>* methods = this->methods();
2825   int num_methods = methods->length();
2826   for (int index = 0; index < num_methods; ++index) {
2827     methods->at(index)->restore_unshareable_info(CHECK);
2828   }
2829 #if INCLUDE_JVMTI
2830   if (JvmtiExport::has_redefined_a_class()) {
2831     // Reinitialize vtable because RedefineClasses may have changed some
2832     // entries in this vtable for super classes so the CDS vtable might
2833     // point to old or obsolete entries.  RedefineClasses doesn't fix up
2834     // vtables in the shared system dictionary, only the main one.
2835     // It also redefines the itable too so fix that too.
2836     // First fix any default methods that point to a super class that may
2837     // have been redefined.
2838     bool trace_name_printed = false;
2839     adjust_default_methods(&trace_name_printed);
2840     if (verified_at_dump_time()) {
2841       // Initialize vtable and itable for classes which can be verified at dump time.
2842       // Unlinked classes such as old classes with major version < 50 cannot be verified
2843       // at dump time.
2844       vtable().initialize_vtable();
2845       itable().initialize_itable();
2846     }
2847   }
2848 #endif // INCLUDE_JVMTI
2849 
2850   // restore constant pool resolved references
2851   constants()->restore_unshareable_info(CHECK);
2852 
2853   if (array_klasses() != nullptr) {
2854     // To get a consistent list of classes we need MultiArray_lock to ensure
2855     // array classes aren't observed while they are being restored.
2856     RecursiveLocker rl(MultiArray_lock, THREAD);
2857     assert(this == array_klasses()->bottom_klass(), "sanity");
2858     // Array classes have null protection domain.
2859     // --> see ArrayKlass::complete_create_array_klass()
2860     array_klasses()->restore_unshareable_info(class_loader_data(), Handle(), CHECK);
2861   }
2862 
2863   // Initialize @ValueBased class annotation if not already set in the archived klass.
2864   if (DiagnoseSyncOnValueBasedClasses && has_value_based_class_annotation() && !is_value_based()) {
2865     set_is_value_based();
2866   }
2867 
2868   DEBUG_ONLY(FieldInfoStream::validate_search_table(_constants, _fieldinfo_stream, _fieldinfo_search_table));
2869 }
2870 
2871 bool InstanceKlass::can_be_verified_at_dumptime() const {
2872   if (CDSConfig::is_dumping_dynamic_archive() && AOTMetaspace::in_aot_cache(this)) {
2873     // This is a class that was dumped into the base archive, so we know
2874     // it was verified at dump time.
2875     return true;
2876   }
2877 
2878   if (CDSConfig::is_preserving_verification_constraints()) {
2879     return true;
2880   }
2881 
2882   if (CDSConfig::is_old_class_for_verifier(this)) {
2883     // The old verifier does not save verification constraints, so at run time
2884     // SystemDictionaryShared::check_verification_constraints() will not work for this class.
2885     return false;
2886   }
2887   if (super() != nullptr && !super()->can_be_verified_at_dumptime()) {
2888     return false;
2889   }
2890   Array<InstanceKlass*>* interfaces = local_interfaces();
2891   int len = interfaces->length();
2892   for (int i = 0; i < len; i++) {
2893     if (!interfaces->at(i)->can_be_verified_at_dumptime()) {
2894       return false;
2895     }
2896   }
2897   return true;
2898 }
2899 
2900 #endif // INCLUDE_CDS
2901 
2902 #if INCLUDE_JVMTI
2903 static void clear_all_breakpoints(Method* m) {
2904   m->clear_all_breakpoints();
2905 }
2906 #endif
2907 
2908 void InstanceKlass::unload_class(InstanceKlass* ik) {
2909 
2910   if (ik->is_scratch_class()) {
2911     assert(ik->dependencies().is_empty(), "dependencies should be empty for scratch classes");
2912     return;
2913   }
2914   assert(ik->is_loaded(), "class should be loaded " PTR_FORMAT, p2i(ik));
2915 
2916   // Release dependencies.
2917   ik->dependencies().remove_all_dependents();
2918 
2919   // notify the debugger
2920   if (JvmtiExport::should_post_class_unload()) {
2921     JvmtiExport::post_class_unload(ik);
2922   }
2923 
2924   // notify ClassLoadingService of class unload
2925   ClassLoadingService::notify_class_unloaded(ik);
2926 
2927   SystemDictionaryShared::handle_class_unloading(ik);
2928 
2929   if (log_is_enabled(Info, class, unload)) {
2930     ResourceMark rm;
2931     log_info(class, unload)("unloading class %s " PTR_FORMAT, ik->external_name(), p2i(ik));
2932   }
2933 
2934   Events::log_class_unloading(Thread::current(), ik);
2935 
2936 #if INCLUDE_JFR
2937   assert(ik != nullptr, "invariant");
2938   EventClassUnload event;
2939   event.set_unloadedClass(ik);
2940   event.set_definingClassLoader(ik->class_loader_data());
2941   event.commit();
2942 #endif
2943 }
2944 
2945 static void method_release_C_heap_structures(Method* m) {
2946   m->release_C_heap_structures();
2947 }
2948 
2949 // Called also by InstanceKlass::deallocate_contents, with false for release_sub_metadata.
2950 void InstanceKlass::release_C_heap_structures(bool release_sub_metadata) {
2951   // Clean up C heap
2952   Klass::release_C_heap_structures();
2953 
2954   // Deallocate and call destructors for MDO mutexes
2955   if (release_sub_metadata) {
2956     methods_do(method_release_C_heap_structures);
2957   }
2958 
2959   // Deallocate oop map cache
2960   if (_oop_map_cache != nullptr) {
2961     delete _oop_map_cache;
2962     _oop_map_cache = nullptr;
2963   }
2964 
2965   // Deallocate JNI identifiers for jfieldIDs
2966   JNIid::deallocate(jni_ids());
2967   set_jni_ids(nullptr);
2968 
2969   jmethodID* jmeths = _methods_jmethod_ids;
2970   if (jmeths != nullptr) {
2971     release_set_methods_jmethod_ids(nullptr);
2972     FreeHeap(jmeths);
2973   }
2974 
2975   assert(_dep_context == nullptr,
2976          "dependencies should already be cleaned");
2977 
2978 #if INCLUDE_JVMTI
2979   // Deallocate breakpoint records
2980   if (breakpoints() != nullptr) {
2981     methods_do(clear_all_breakpoints);
2982     assert(breakpoints() == nullptr, "should have cleared breakpoints");
2983   }
2984 
2985   // deallocate the cached class file
2986   if (_cached_class_file != nullptr) {
2987     os::free(_cached_class_file);
2988     _cached_class_file = nullptr;
2989   }
2990 #endif
2991 
2992   FREE_C_HEAP_ARRAY(char, _source_debug_extension);
2993 
2994   if (release_sub_metadata) {
2995     constants()->release_C_heap_structures();
2996   }
2997 }
2998 
2999 // The constant pool is on stack if any of the methods are executing or
3000 // referenced by handles.
3001 bool InstanceKlass::on_stack() const {
3002   return _constants->on_stack();
3003 }
3004 
3005 Symbol* InstanceKlass::source_file_name() const               { return _constants->source_file_name(); }
3006 u2 InstanceKlass::source_file_name_index() const              { return _constants->source_file_name_index(); }
3007 void InstanceKlass::set_source_file_name_index(u2 sourcefile_index) { _constants->set_source_file_name_index(sourcefile_index); }
3008 
3009 // minor and major version numbers of class file
3010 u2 InstanceKlass::minor_version() const                 { return _constants->minor_version(); }
3011 void InstanceKlass::set_minor_version(u2 minor_version) { _constants->set_minor_version(minor_version); }
3012 u2 InstanceKlass::major_version() const                 { return _constants->major_version(); }
3013 void InstanceKlass::set_major_version(u2 major_version) { _constants->set_major_version(major_version); }
3014 
3015 const InstanceKlass* InstanceKlass::get_klass_version(int version) const {
3016   for (const InstanceKlass* ik = this; ik != nullptr; ik = ik->previous_versions()) {
3017     if (ik->constants()->version() == version) {
3018       return ik;
3019     }
3020   }
3021   return nullptr;
3022 }
3023 
3024 void InstanceKlass::set_source_debug_extension(const char* array, int length) {
3025   if (array == nullptr) {
3026     _source_debug_extension = nullptr;
3027   } else {
3028     // Adding one to the attribute length in order to store a null terminator
3029     // character could cause an overflow because the attribute length is
3030     // already coded with an u4 in the classfile, but in practice, it's
3031     // unlikely to happen.
3032     assert((length+1) > length, "Overflow checking");
3033     char* sde = NEW_C_HEAP_ARRAY(char, (length + 1), mtClass);
3034     for (int i = 0; i < length; i++) {
3035       sde[i] = array[i];
3036     }
3037     sde[length] = '\0';
3038     _source_debug_extension = sde;
3039   }
3040 }
3041 
3042 Symbol* InstanceKlass::generic_signature() const                   { return _constants->generic_signature(); }
3043 u2 InstanceKlass::generic_signature_index() const                  { return _constants->generic_signature_index(); }
3044 void InstanceKlass::set_generic_signature_index(u2 sig_index)      { _constants->set_generic_signature_index(sig_index); }
3045 
3046 const char* InstanceKlass::signature_name() const {
3047 
3048   // Get the internal name as a c string
3049   const char* src = (const char*) (name()->as_C_string());
3050   const int src_length = (int)strlen(src);
3051 
3052   char* dest = NEW_RESOURCE_ARRAY(char, src_length + 3);
3053 
3054   // Add L as type indicator
3055   int dest_index = 0;
3056   dest[dest_index++] = JVM_SIGNATURE_CLASS;
3057 
3058   // Add the actual class name
3059   for (int src_index = 0; src_index < src_length; ) {
3060     dest[dest_index++] = src[src_index++];
3061   }
3062 
3063   if (is_hidden()) { // Replace the last '+' with a '.'.
3064     for (int index = (int)src_length; index > 0; index--) {
3065       if (dest[index] == '+') {
3066         dest[index] = JVM_SIGNATURE_DOT;
3067         break;
3068       }
3069     }
3070   }
3071 
3072   // Add the semicolon and the null
3073   dest[dest_index++] = JVM_SIGNATURE_ENDCLASS;
3074   dest[dest_index] = '\0';
3075   return dest;
3076 }
3077 
3078 ModuleEntry* InstanceKlass::module() const {
3079   if (is_hidden() &&
3080       in_unnamed_package() &&
3081       class_loader_data()->has_class_mirror_holder()) {
3082     // For a non-strong hidden class defined to an unnamed package,
3083     // its (class held) CLD will not have an unnamed module created for it.
3084     // Two choices to find the correct ModuleEntry:
3085     // 1. If hidden class is within a nest, use nest host's module
3086     // 2. Find the unnamed module off from the class loader
3087     // For now option #2 is used since a nest host is not set until
3088     // after the instance class is created in jvm_lookup_define_class().
3089     if (class_loader_data()->is_boot_class_loader_data()) {
3090       return ClassLoaderData::the_null_class_loader_data()->unnamed_module();
3091     } else {
3092       oop module = java_lang_ClassLoader::unnamedModule(class_loader_data()->class_loader());
3093       assert(java_lang_Module::is_instance(module), "Not an instance of java.lang.Module");
3094       return java_lang_Module::module_entry(module);
3095     }
3096   }
3097 
3098   // Class is in a named package
3099   if (!in_unnamed_package()) {
3100     return _package_entry->module();
3101   }
3102 
3103   // Class is in an unnamed package, return its loader's unnamed module
3104   return class_loader_data()->unnamed_module();
3105 }
3106 
3107 bool InstanceKlass::in_javabase_module() const {
3108   return module()->name() == vmSymbols::java_base();
3109 }
3110 
3111 void InstanceKlass::set_package(ClassLoaderData* loader_data, PackageEntry* pkg_entry, TRAPS) {
3112 
3113   // ensure java/ packages only loaded by boot or platform builtin loaders
3114   // not needed for shared class since CDS does not archive prohibited classes.
3115   if (!in_aot_cache()) {
3116     check_prohibited_package(name(), loader_data, CHECK);
3117   }
3118 
3119   if (in_aot_cache() && _package_entry != nullptr) {
3120     if (CDSConfig::is_using_full_module_graph() && _package_entry == pkg_entry) {
3121       // we can use the saved package
3122       assert(AOTMetaspace::in_aot_cache(_package_entry), "must be");
3123       return;
3124     } else {
3125       _package_entry = nullptr;
3126     }
3127   }
3128 
3129   // ClassLoader::package_from_class_name has already incremented the refcount of the symbol
3130   // it returns, so we need to decrement it when the current function exits.
3131   TempNewSymbol from_class_name =
3132       (pkg_entry != nullptr) ? nullptr : ClassLoader::package_from_class_name(name());
3133 
3134   Symbol* pkg_name;
3135   if (pkg_entry != nullptr) {
3136     pkg_name = pkg_entry->name();
3137   } else {
3138     pkg_name = from_class_name;
3139   }
3140 
3141   if (pkg_name != nullptr && loader_data != nullptr) {
3142 
3143     // Find in class loader's package entry table.
3144     _package_entry = pkg_entry != nullptr ? pkg_entry : loader_data->packages()->lookup_only(pkg_name);
3145 
3146     // If the package name is not found in the loader's package
3147     // entry table, it is an indication that the package has not
3148     // been defined. Consider it defined within the unnamed module.
3149     if (_package_entry == nullptr) {
3150 
3151       if (!ModuleEntryTable::javabase_defined()) {
3152         // Before java.base is defined during bootstrapping, define all packages in
3153         // the java.base module.  If a non-java.base package is erroneously placed
3154         // in the java.base module it will be caught later when java.base
3155         // is defined by ModuleEntryTable::verify_javabase_packages check.
3156         assert(ModuleEntryTable::javabase_moduleEntry() != nullptr, JAVA_BASE_NAME " module is null");
3157         _package_entry = loader_data->packages()->create_entry_if_absent(pkg_name, ModuleEntryTable::javabase_moduleEntry());
3158       } else {
3159         assert(loader_data->unnamed_module() != nullptr, "unnamed module is null");
3160         _package_entry = loader_data->packages()->create_entry_if_absent(pkg_name, loader_data->unnamed_module());
3161       }
3162 
3163       // A package should have been successfully created
3164       DEBUG_ONLY(ResourceMark rm(THREAD));
3165       assert(_package_entry != nullptr, "Package entry for class %s not found, loader %s",
3166              name()->as_C_string(), loader_data->loader_name_and_id());
3167     }
3168 
3169     if (log_is_enabled(Debug, module)) {
3170       ResourceMark rm(THREAD);
3171       ModuleEntry* m = _package_entry->module();
3172       log_trace(module)("Setting package: class: %s, package: %s, loader: %s, module: %s",
3173                         external_name(),
3174                         pkg_name->as_C_string(),
3175                         loader_data->loader_name_and_id(),
3176                         (m->is_named() ? m->name()->as_C_string() : UNNAMED_MODULE));
3177     }
3178   } else {
3179     ResourceMark rm(THREAD);
3180     log_trace(module)("Setting package: class: %s, package: unnamed, loader: %s, module: %s",
3181                       external_name(),
3182                       (loader_data != nullptr) ? loader_data->loader_name_and_id() : "null",
3183                       UNNAMED_MODULE);
3184   }
3185 }
3186 
3187 // Function set_classpath_index ensures that for a non-null _package_entry
3188 // of the InstanceKlass, the entry is in the boot loader's package entry table.
3189 // It then sets the classpath_index in the package entry record.
3190 //
3191 // The classpath_index field is used to find the entry on the boot loader class
3192 // path for packages with classes loaded by the boot loader from -Xbootclasspath/a
3193 // in an unnamed module.  It is also used to indicate (for all packages whose
3194 // classes are loaded by the boot loader) that at least one of the package's
3195 // classes has been loaded.
3196 void InstanceKlass::set_classpath_index(s2 path_index) {
3197   if (_package_entry != nullptr) {
3198     DEBUG_ONLY(PackageEntryTable* pkg_entry_tbl = ClassLoaderData::the_null_class_loader_data()->packages();)
3199     assert(pkg_entry_tbl->lookup_only(_package_entry->name()) == _package_entry, "Should be same");
3200     assert(path_index != -1, "Unexpected classpath_index");
3201     _package_entry->set_classpath_index(path_index);
3202   }
3203 }
3204 
3205 // different versions of is_same_class_package
3206 
3207 bool InstanceKlass::is_same_class_package(const Klass* class2) const {
3208   oop classloader1 = this->class_loader();
3209   PackageEntry* classpkg1 = this->package();
3210   if (class2->is_objArray_klass()) {
3211     class2 = ObjArrayKlass::cast(class2)->bottom_klass();
3212   }
3213 
3214   oop classloader2;
3215   PackageEntry* classpkg2;
3216   if (class2->is_instance_klass()) {
3217     classloader2 = class2->class_loader();
3218     classpkg2 = class2->package();
3219   } else {
3220     assert(class2->is_typeArray_klass(), "should be type array");
3221     classloader2 = nullptr;
3222     classpkg2 = nullptr;
3223   }
3224 
3225   // Same package is determined by comparing class loader
3226   // and package entries. Both must be the same. This rule
3227   // applies even to classes that are defined in the unnamed
3228   // package, they still must have the same class loader.
3229   if ((classloader1 == classloader2) && (classpkg1 == classpkg2)) {
3230     return true;
3231   }
3232 
3233   return false;
3234 }
3235 
3236 // return true if this class and other_class are in the same package. Classloader
3237 // and classname information is enough to determine a class's package
3238 bool InstanceKlass::is_same_class_package(oop other_class_loader,
3239                                           const Symbol* other_class_name) const {
3240   if (class_loader() != other_class_loader) {
3241     return false;
3242   }
3243   if (name()->fast_compare(other_class_name) == 0) {
3244      return true;
3245   }
3246 
3247   {
3248     ResourceMark rm;
3249 
3250     bool bad_class_name = false;
3251     TempNewSymbol other_pkg = ClassLoader::package_from_class_name(other_class_name, &bad_class_name);
3252     if (bad_class_name) {
3253       return false;
3254     }
3255     // Check that package_from_class_name() returns null, not "", if there is no package.
3256     assert(other_pkg == nullptr || other_pkg->utf8_length() > 0, "package name is empty string");
3257 
3258     const Symbol* const this_package_name =
3259       this->package() != nullptr ? this->package()->name() : nullptr;
3260 
3261     if (this_package_name == nullptr || other_pkg == nullptr) {
3262       // One of the two doesn't have a package.  Only return true if the other
3263       // one also doesn't have a package.
3264       return this_package_name == other_pkg;
3265     }
3266 
3267     // Check if package is identical
3268     return this_package_name->fast_compare(other_pkg) == 0;
3269   }
3270 }
3271 
3272 static bool is_prohibited_package_slow(Symbol* class_name) {
3273   // Caller has ResourceMark
3274   int length;
3275   jchar* unicode = class_name->as_unicode(length);
3276   return (length >= 5 &&
3277           unicode[0] == 'j' &&
3278           unicode[1] == 'a' &&
3279           unicode[2] == 'v' &&
3280           unicode[3] == 'a' &&
3281           unicode[4] == '/');
3282 }
3283 
3284 // Only boot and platform class loaders can define classes in "java/" packages.
3285 void InstanceKlass::check_prohibited_package(Symbol* class_name,
3286                                              ClassLoaderData* loader_data,
3287                                              TRAPS) {
3288   if (!loader_data->is_boot_class_loader_data() &&
3289       !loader_data->is_platform_class_loader_data() &&
3290       class_name != nullptr && class_name->utf8_length() >= 5) {
3291     ResourceMark rm(THREAD);
3292     bool prohibited;
3293     const u1* base = class_name->base();
3294     if ((base[0] | base[1] | base[2] | base[3] | base[4]) & 0x80) {
3295       prohibited = is_prohibited_package_slow(class_name);
3296     } else {
3297       char* name = class_name->as_C_string();
3298       prohibited = (strncmp(name, JAVAPKG, JAVAPKG_LEN) == 0 && name[JAVAPKG_LEN] == '/');
3299     }
3300     if (prohibited) {
3301       TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
3302       assert(pkg_name != nullptr, "Error in parsing package name starting with 'java/'");
3303       char* name = pkg_name->as_C_string();
3304       const char* class_loader_name = loader_data->loader_name_and_id();
3305       StringUtils::replace_no_expand(name, "/", ".");
3306       const char* msg_text1 = "Class loader (instance of): ";
3307       const char* msg_text2 = " tried to load prohibited package name: ";
3308       size_t len = strlen(msg_text1) + strlen(class_loader_name) + strlen(msg_text2) + strlen(name) + 1;
3309       char* message = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
3310       jio_snprintf(message, len, "%s%s%s%s", msg_text1, class_loader_name, msg_text2, name);
3311       THROW_MSG(vmSymbols::java_lang_SecurityException(), message);
3312     }
3313   }
3314   return;
3315 }
3316 
3317 bool InstanceKlass::find_inner_classes_attr(int* ooff, int* noff, TRAPS) const {
3318   constantPoolHandle i_cp(THREAD, constants());
3319   for (InnerClassesIterator iter(this); !iter.done(); iter.next()) {
3320     int ioff = iter.inner_class_info_index();
3321     if (ioff != 0) {
3322       // Check to see if the name matches the class we're looking for
3323       // before attempting to find the class.
3324       if (i_cp->klass_name_at_matches(this, ioff)) {
3325         Klass* inner_klass = i_cp->klass_at(ioff, CHECK_false);
3326         if (this == inner_klass) {
3327           *ooff = iter.outer_class_info_index();
3328           *noff = iter.inner_name_index();
3329           return true;
3330         }
3331       }
3332     }
3333   }
3334   return false;
3335 }
3336 
3337 InstanceKlass* InstanceKlass::compute_enclosing_class(bool* inner_is_member, TRAPS) const {
3338   InstanceKlass* outer_klass = nullptr;
3339   *inner_is_member = false;
3340   int ooff = 0, noff = 0;
3341   bool has_inner_classes_attr = find_inner_classes_attr(&ooff, &noff, THREAD);
3342   if (has_inner_classes_attr) {
3343     constantPoolHandle i_cp(THREAD, constants());
3344     if (ooff != 0) {
3345       Klass* ok = i_cp->klass_at(ooff, CHECK_NULL);
3346       if (!ok->is_instance_klass()) {
3347         // If the outer class is not an instance klass then it cannot have
3348         // declared any inner classes.
3349         ResourceMark rm(THREAD);
3350         // Names are all known to be < 64k so we know this formatted message is not excessively large.
3351         Exceptions::fthrow(
3352           THREAD_AND_LOCATION,
3353           vmSymbols::java_lang_IncompatibleClassChangeError(),
3354           "%s and %s disagree on InnerClasses attribute",
3355           ok->external_name(),
3356           external_name());
3357         return nullptr;
3358       }
3359       outer_klass = InstanceKlass::cast(ok);
3360       *inner_is_member = true;
3361     }
3362     if (nullptr == outer_klass) {
3363       // It may be a local class; try for that.
3364       int encl_method_class_idx = enclosing_method_class_index();
3365       if (encl_method_class_idx != 0) {
3366         Klass* ok = i_cp->klass_at(encl_method_class_idx, CHECK_NULL);
3367         outer_klass = InstanceKlass::cast(ok);
3368         *inner_is_member = false;
3369       }
3370     }
3371   }
3372 
3373   // If no inner class attribute found for this class.
3374   if (nullptr == outer_klass) return nullptr;
3375 
3376   // Throws an exception if outer klass has not declared k as an inner klass
3377   // We need evidence that each klass knows about the other, or else
3378   // the system could allow a spoof of an inner class to gain access rights.
3379   Reflection::check_for_inner_class(outer_klass, this, *inner_is_member, CHECK_NULL);
3380   return outer_klass;
3381 }
3382 
3383 u2 InstanceKlass::compute_modifier_flags() const {
3384   u2 access = access_flags().as_unsigned_short();
3385 
3386   // But check if it happens to be member class.
3387   InnerClassesIterator iter(this);
3388   for (; !iter.done(); iter.next()) {
3389     int ioff = iter.inner_class_info_index();
3390     // Inner class attribute can be zero, skip it.
3391     // Strange but true:  JVM spec. allows null inner class refs.
3392     if (ioff == 0) continue;
3393 
3394     // only look at classes that are already loaded
3395     // since we are looking for the flags for our self.
3396     Symbol* inner_name = constants()->klass_name_at(ioff);
3397     if (name() == inner_name) {
3398       // This is really a member class.
3399       access = iter.inner_access_flags();
3400       break;
3401     }
3402   }
3403   // Remember to strip ACC_SUPER bit
3404   return (access & (~JVM_ACC_SUPER));
3405 }
3406 
3407 jint InstanceKlass::jvmti_class_status() const {
3408   jint result = 0;
3409 
3410   if (is_linked()) {
3411     result |= JVMTI_CLASS_STATUS_VERIFIED | JVMTI_CLASS_STATUS_PREPARED;
3412   }
3413 
3414   if (is_initialized()) {
3415     assert(is_linked(), "Class status is not consistent");
3416     result |= JVMTI_CLASS_STATUS_INITIALIZED;
3417   }
3418   if (is_in_error_state()) {
3419     result |= JVMTI_CLASS_STATUS_ERROR;
3420   }
3421   return result;
3422 }
3423 
3424 Method* InstanceKlass::method_at_itable(InstanceKlass* holder, int index, TRAPS) {
3425   bool implements_interface; // initialized by method_at_itable_or_null
3426   Method* m = method_at_itable_or_null(holder, index,
3427                                        implements_interface); // out parameter
3428   if (m != nullptr) {
3429     assert(implements_interface, "sanity");
3430     return m;
3431   } else if (implements_interface) {
3432     // Throw AbstractMethodError since corresponding itable slot is empty.
3433     THROW_NULL(vmSymbols::java_lang_AbstractMethodError());
3434   } else {
3435     // If the interface isn't implemented by the receiver class,
3436     // the VM should throw IncompatibleClassChangeError.
3437     ResourceMark rm(THREAD);
3438     stringStream ss;
3439     bool same_module = (module() == holder->module());
3440     ss.print("Receiver class %s does not implement "
3441              "the interface %s defining the method to be called "
3442              "(%s%s%s)",
3443              external_name(), holder->external_name(),
3444              (same_module) ? joint_in_module_of_loader(holder) : class_in_module_of_loader(),
3445              (same_module) ? "" : "; ",
3446              (same_module) ? "" : holder->class_in_module_of_loader());
3447     THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), ss.as_string());
3448   }
3449 }
3450 
3451 Method* InstanceKlass::method_at_itable_or_null(InstanceKlass* holder, int index, bool& implements_interface) {
3452   klassItable itable(this);
3453   for (int i = 0; i < itable.size_offset_table(); i++) {
3454     itableOffsetEntry* offset_entry = itable.offset_entry(i);
3455     if (offset_entry->interface_klass() == holder) {
3456       implements_interface = true;
3457       itableMethodEntry* ime = offset_entry->first_method_entry(this);
3458       Method* m = ime[index].method();
3459       return m;
3460     }
3461   }
3462   implements_interface = false;
3463   return nullptr; // offset entry not found
3464 }
3465 
3466 int InstanceKlass::vtable_index_of_interface_method(Method* intf_method) {
3467   assert(is_linked(), "required");
3468   assert(intf_method->method_holder()->is_interface(), "not an interface method");
3469   assert(is_subtype_of(intf_method->method_holder()), "interface not implemented");
3470 
3471   int vtable_index = Method::invalid_vtable_index;
3472   Symbol* name = intf_method->name();
3473   Symbol* signature = intf_method->signature();
3474 
3475   // First check in default method array
3476   if (!intf_method->is_abstract() && default_methods() != nullptr) {
3477     int index = find_method_index(default_methods(),
3478                                   name, signature,
3479                                   Klass::OverpassLookupMode::find,
3480                                   Klass::StaticLookupMode::find,
3481                                   Klass::PrivateLookupMode::find);
3482     if (index >= 0) {
3483       vtable_index = default_vtable_indices()->at(index);
3484     }
3485   }
3486   if (vtable_index == Method::invalid_vtable_index) {
3487     // get vtable_index for miranda methods
3488     klassVtable vt = vtable();
3489     vtable_index = vt.index_of_miranda(name, signature);
3490   }
3491   return vtable_index;
3492 }
3493 
3494 #if INCLUDE_JVMTI
3495 // update default_methods for redefineclasses for methods that are
3496 // not yet in the vtable due to concurrent subclass define and superinterface
3497 // redefinition
3498 // Note: those in the vtable, should have been updated via adjust_method_entries
3499 void InstanceKlass::adjust_default_methods(bool* trace_name_printed) {
3500   // search the default_methods for uses of either obsolete or EMCP methods
3501   if (default_methods() != nullptr) {
3502     for (int index = 0; index < default_methods()->length(); index ++) {
3503       Method* old_method = default_methods()->at(index);
3504       if (old_method == nullptr || !old_method->is_old()) {
3505         continue; // skip uninteresting entries
3506       }
3507       assert(!old_method->is_deleted(), "default methods may not be deleted");
3508       Method* new_method = old_method->get_new_method();
3509       default_methods()->at_put(index, new_method);
3510 
3511       if (log_is_enabled(Info, redefine, class, update)) {
3512         ResourceMark rm;
3513         if (!(*trace_name_printed)) {
3514           log_info(redefine, class, update)
3515             ("adjust: klassname=%s default methods from name=%s",
3516              external_name(), old_method->method_holder()->external_name());
3517           *trace_name_printed = true;
3518         }
3519         log_debug(redefine, class, update, vtables)
3520           ("default method update: %s(%s) ",
3521            new_method->name()->as_C_string(), new_method->signature()->as_C_string());
3522       }
3523     }
3524   }
3525 }
3526 #endif // INCLUDE_JVMTI
3527 
3528 // On-stack replacement stuff
3529 void InstanceKlass::add_osr_nmethod(nmethod* n) {
3530   assert_lock_strong(NMethodState_lock);
3531 #ifndef PRODUCT
3532   nmethod* prev = lookup_osr_nmethod(n->method(), n->osr_entry_bci(), n->comp_level(), true);
3533   assert(prev == nullptr || !prev->is_in_use() COMPILER2_PRESENT(|| StressRecompilation),
3534       "redundant OSR recompilation detected. memory leak in CodeCache!");
3535 #endif
3536   // only one compilation can be active
3537   assert(n->is_osr_method(), "wrong kind of nmethod");
3538   n->set_osr_link(osr_nmethods_head());
3539   set_osr_nmethods_head(n);
3540   // Raise the highest osr level if necessary
3541   n->method()->set_highest_osr_comp_level(MAX2(n->method()->highest_osr_comp_level(), n->comp_level()));
3542 
3543   // Get rid of the osr methods for the same bci that have lower levels.
3544   for (int l = CompLevel_limited_profile; l < n->comp_level(); l++) {
3545     nmethod *inv = lookup_osr_nmethod(n->method(), n->osr_entry_bci(), l, true);
3546     if (inv != nullptr && inv->is_in_use()) {
3547       inv->make_not_entrant(nmethod::InvalidationReason::OSR_INVALIDATION_OF_LOWER_LEVEL);
3548     }
3549   }
3550 }
3551 
3552 // Remove osr nmethod from the list. Return true if found and removed.
3553 bool InstanceKlass::remove_osr_nmethod(nmethod* n) {
3554   // This is a short non-blocking critical region, so the no safepoint check is ok.
3555   ConditionalMutexLocker ml(NMethodState_lock, !NMethodState_lock->owned_by_self(), Mutex::_no_safepoint_check_flag);
3556   assert(n->is_osr_method(), "wrong kind of nmethod");
3557   nmethod* last = nullptr;
3558   nmethod* cur  = osr_nmethods_head();
3559   int max_level = CompLevel_none;  // Find the max comp level excluding n
3560   Method* m = n->method();
3561   // Search for match
3562   bool found = false;
3563   while(cur != nullptr && cur != n) {
3564     if (m == cur->method()) {
3565       // Find max level before n
3566       max_level = MAX2(max_level, cur->comp_level());
3567     }
3568     last = cur;
3569     cur = cur->osr_link();
3570   }
3571   nmethod* next = nullptr;
3572   if (cur == n) {
3573     found = true;
3574     next = cur->osr_link();
3575     if (last == nullptr) {
3576       // Remove first element
3577       set_osr_nmethods_head(next);
3578     } else {
3579       last->set_osr_link(next);
3580     }
3581   }
3582   n->set_osr_link(nullptr);
3583   cur = next;
3584   while (cur != nullptr) {
3585     // Find max level after n
3586     if (m == cur->method()) {
3587       max_level = MAX2(max_level, cur->comp_level());
3588     }
3589     cur = cur->osr_link();
3590   }
3591   m->set_highest_osr_comp_level(max_level);
3592   return found;
3593 }
3594 
3595 int InstanceKlass::mark_osr_nmethods(DeoptimizationScope* deopt_scope, const Method* m) {
3596   ConditionalMutexLocker ml(NMethodState_lock, !NMethodState_lock->owned_by_self(), Mutex::_no_safepoint_check_flag);
3597   nmethod* osr = osr_nmethods_head();
3598   int found = 0;
3599   while (osr != nullptr) {
3600     assert(osr->is_osr_method(), "wrong kind of nmethod found in chain");
3601     if (osr->method() == m) {
3602       deopt_scope->mark(osr);
3603       found++;
3604     }
3605     osr = osr->osr_link();
3606   }
3607   return found;
3608 }
3609 
3610 nmethod* InstanceKlass::lookup_osr_nmethod(const Method* m, int bci, int comp_level, bool match_level) const {
3611   ConditionalMutexLocker ml(NMethodState_lock, !NMethodState_lock->owned_by_self(), Mutex::_no_safepoint_check_flag);
3612   nmethod* osr = osr_nmethods_head();
3613   nmethod* best = nullptr;
3614   while (osr != nullptr) {
3615     assert(osr->is_osr_method(), "wrong kind of nmethod found in chain");
3616     // There can be a time when a c1 osr method exists but we are waiting
3617     // for a c2 version. When c2 completes its osr nmethod we will trash
3618     // the c1 version and only be able to find the c2 version. However
3619     // while we overflow in the c1 code at back branches we don't want to
3620     // try and switch to the same code as we are already running
3621 
3622     if (osr->method() == m &&
3623         (bci == InvocationEntryBci || osr->osr_entry_bci() == bci)) {
3624       if (match_level) {
3625         if (osr->comp_level() == comp_level) {
3626           // Found a match - return it.
3627           return osr;
3628         }
3629       } else {
3630         if (best == nullptr || (osr->comp_level() > best->comp_level())) {
3631           if (osr->comp_level() == CompilationPolicy::highest_compile_level()) {
3632             // Found the best possible - return it.
3633             return osr;
3634           }
3635           best = osr;
3636         }
3637       }
3638     }
3639     osr = osr->osr_link();
3640   }
3641 
3642   assert(match_level == false || best == nullptr, "shouldn't pick up anything if match_level is set");
3643   if (best != nullptr && best->comp_level() >= comp_level) {
3644     return best;
3645   }
3646   return nullptr;
3647 }
3648 
3649 // -----------------------------------------------------------------------------------------------------
3650 // Printing
3651 
3652 #define BULLET  " - "
3653 
3654 static const char* state_names[] = {
3655   "allocated", "loaded", "linked", "being_initialized", "fully_initialized", "initialization_error"
3656 };
3657 
3658 static void print_vtable(intptr_t* start, int len, outputStream* st) {
3659   for (int i = 0; i < len; i++) {
3660     intptr_t e = start[i];
3661     st->print("%d : " INTPTR_FORMAT, i, e);
3662     if (MetaspaceObj::is_valid((Metadata*)e)) {
3663       st->print(" ");
3664       ((Metadata*)e)->print_value_on(st);
3665     }
3666     st->cr();
3667   }
3668 }
3669 
3670 static void print_vtable(vtableEntry* start, int len, outputStream* st) {
3671   return print_vtable(reinterpret_cast<intptr_t*>(start), len, st);
3672 }
3673 
3674 const char* InstanceKlass::init_state_name() const {
3675   return state_names[init_state()];
3676 }
3677 
3678 void InstanceKlass::print_on(outputStream* st) const {
3679   assert(is_klass(), "must be klass");
3680   Klass::print_on(st);
3681 
3682   st->print(BULLET"instance size:     %d", size_helper());                        st->cr();
3683   st->print(BULLET"klass size:        %d", size());                               st->cr();
3684   st->print(BULLET"access:            "); access_flags().print_on(st);            st->cr();
3685   st->print(BULLET"flags:             "); _misc_flags.print_on(st);               st->cr();
3686   st->print(BULLET"state:             "); st->print_cr("%s", init_state_name());
3687   st->print(BULLET"name:              "); name()->print_value_on(st);             st->cr();
3688   st->print(BULLET"super:             "); Metadata::print_value_on_maybe_null(st, super()); st->cr();
3689   st->print(BULLET"sub:               ");
3690   Klass* sub = subklass();
3691   int n;
3692   for (n = 0; sub != nullptr; n++, sub = sub->next_sibling()) {
3693     if (n < MaxSubklassPrintSize) {
3694       sub->print_value_on(st);
3695       st->print("   ");
3696     }
3697   }
3698   if (n >= MaxSubklassPrintSize) st->print("(%zd more klasses...)", n - MaxSubklassPrintSize);
3699   st->cr();
3700 
3701   if (is_interface()) {
3702     st->print_cr(BULLET"nof implementors:  %d", nof_implementors());
3703     if (nof_implementors() == 1) {
3704       st->print_cr(BULLET"implementor:    ");
3705       st->print("   ");
3706       implementor()->print_value_on(st);
3707       st->cr();
3708     }
3709   }
3710 
3711   st->print(BULLET"arrays:            "); Metadata::print_value_on_maybe_null(st, array_klasses()); st->cr();
3712   st->print(BULLET"methods:           "); methods()->print_value_on(st);               st->cr();
3713   if (Verbose || WizardMode) {
3714     Array<Method*>* method_array = methods();
3715     for (int i = 0; i < method_array->length(); i++) {
3716       st->print("%d : ", i); method_array->at(i)->print_value(); st->cr();
3717     }
3718   }
3719   st->print(BULLET"method ordering:   "); method_ordering()->print_value_on(st);      st->cr();
3720   if (default_methods() != nullptr) {
3721     st->print(BULLET"default_methods:   "); default_methods()->print_value_on(st);    st->cr();
3722     if (Verbose) {
3723       Array<Method*>* method_array = default_methods();
3724       for (int i = 0; i < method_array->length(); i++) {
3725         st->print("%d : ", i); method_array->at(i)->print_value(); st->cr();
3726       }
3727     }
3728   }
3729   print_on_maybe_null(st, BULLET"default vtable indices:   ", default_vtable_indices());
3730   st->print(BULLET"local interfaces:  "); local_interfaces()->print_value_on(st);      st->cr();
3731   st->print(BULLET"trans. interfaces: "); transitive_interfaces()->print_value_on(st); st->cr();
3732 
3733   st->print(BULLET"secondary supers: "); secondary_supers()->print_value_on(st); st->cr();
3734 
3735   st->print(BULLET"hash_slot:         %d", hash_slot()); st->cr();
3736   st->print(BULLET"secondary bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap); st->cr();
3737 
3738   if (secondary_supers() != nullptr) {
3739     if (Verbose) {
3740       bool is_hashed = (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL);
3741       st->print_cr(BULLET"---- secondary supers (%d words):", _secondary_supers->length());
3742       for (int i = 0; i < _secondary_supers->length(); i++) {
3743         ResourceMark rm; // for external_name()
3744         Klass* secondary_super = _secondary_supers->at(i);
3745         st->print(BULLET"%2d:", i);
3746         if (is_hashed) {
3747           int home_slot = compute_home_slot(secondary_super, _secondary_supers_bitmap);
3748           int distance = (i - home_slot) & SECONDARY_SUPERS_TABLE_MASK;
3749           st->print(" dist:%02d:", distance);
3750         }
3751         st->print_cr(" %p %s", secondary_super, secondary_super->external_name());
3752       }
3753     }
3754   }
3755   st->print(BULLET"constants:         "); constants()->print_value_on(st);         st->cr();
3756 
3757   print_on_maybe_null(st, BULLET"class loader data:  ", class_loader_data());
3758   print_on_maybe_null(st, BULLET"source file:       ", source_file_name());
3759   if (source_debug_extension() != nullptr) {
3760     st->print(BULLET"source debug extension:       ");
3761     st->print("%s", source_debug_extension());
3762     st->cr();
3763   }
3764   print_on_maybe_null(st, BULLET"class annotations:       ", class_annotations());
3765   print_on_maybe_null(st, BULLET"class type annotations:  ", class_type_annotations());
3766   print_on_maybe_null(st, BULLET"field annotations:       ", fields_annotations());
3767   print_on_maybe_null(st, BULLET"field type annotations:  ", fields_type_annotations());
3768   {
3769     bool have_pv = false;
3770     // previous versions are linked together through the InstanceKlass
3771     for (InstanceKlass* pv_node = previous_versions();
3772          pv_node != nullptr;
3773          pv_node = pv_node->previous_versions()) {
3774       if (!have_pv)
3775         st->print(BULLET"previous version:  ");
3776       have_pv = true;
3777       pv_node->constants()->print_value_on(st);
3778     }
3779     if (have_pv) st->cr();
3780   }
3781 
3782   print_on_maybe_null(st, BULLET"generic signature: ", generic_signature());
3783   st->print(BULLET"inner classes:     "); inner_classes()->print_value_on(st);     st->cr();
3784   st->print(BULLET"nest members:     "); nest_members()->print_value_on(st);     st->cr();
3785   print_on_maybe_null(st, BULLET"record components:     ", record_components());
3786   st->print(BULLET"permitted subclasses:     "); permitted_subclasses()->print_value_on(st);     st->cr();
3787   if (java_mirror() != nullptr) {
3788     st->print(BULLET"java mirror:       ");
3789     java_mirror()->print_value_on(st);
3790     st->cr();
3791   } else {
3792     st->print_cr(BULLET"java mirror:       null");
3793   }
3794   st->print(BULLET"vtable length      %d  (start addr: " PTR_FORMAT ")", vtable_length(), p2i(start_of_vtable())); st->cr();
3795   if (vtable_length() > 0 && (Verbose || WizardMode))  print_vtable(start_of_vtable(), vtable_length(), st);
3796   st->print(BULLET"itable length      %d (start addr: " PTR_FORMAT ")", itable_length(), p2i(start_of_itable())); st->cr();
3797   if (itable_length() > 0 && (Verbose || WizardMode))  print_vtable(start_of_itable(), itable_length(), st);
3798   st->print_cr(BULLET"---- static fields (%d words):", static_field_size());
3799 
3800   FieldPrinter print_static_field(st);
3801   ((InstanceKlass*)this)->do_local_static_fields(&print_static_field);
3802   st->print_cr(BULLET"---- non-static fields (%d words):", nonstatic_field_size());
3803   FieldPrinter print_nonstatic_field(st);
3804   InstanceKlass* ik = const_cast<InstanceKlass*>(this);
3805   ik->print_nonstatic_fields(&print_nonstatic_field);
3806 
3807   st->print(BULLET"non-static oop maps (%d entries): ", nonstatic_oop_map_count());
3808   OopMapBlock* map     = start_of_nonstatic_oop_maps();
3809   OopMapBlock* end_map = map + nonstatic_oop_map_count();
3810   while (map < end_map) {
3811     st->print("%d-%d ", map->offset(), map->offset() + heapOopSize*(map->count() - 1));
3812     map++;
3813   }
3814   st->cr();
3815 
3816   if (fieldinfo_search_table() != nullptr) {
3817     st->print_cr(BULLET"---- field info search table:");
3818     FieldInfoStream::print_search_table(st, _constants, _fieldinfo_stream, _fieldinfo_search_table);
3819   }
3820 }
3821 
3822 void InstanceKlass::print_value_on(outputStream* st) const {
3823   assert(is_klass(), "must be klass");
3824   if (Verbose || WizardMode)  access_flags().print_on(st);
3825   name()->print_value_on(st);
3826 }
3827 
3828 void FieldPrinter::do_field(fieldDescriptor* fd) {
3829   _st->print(BULLET);
3830    if (_obj == nullptr) {
3831      fd->print_on(_st);
3832      _st->cr();
3833    } else {
3834      fd->print_on_for(_st, _obj);
3835      _st->cr();
3836    }
3837 }
3838 
3839 
3840 void InstanceKlass::oop_print_on(oop obj, outputStream* st) {
3841   Klass::oop_print_on(obj, st);
3842 
3843   if (this == vmClasses::String_klass()) {
3844     typeArrayOop value  = java_lang_String::value(obj);
3845     juint        length = java_lang_String::length(obj);
3846     if (value != nullptr &&
3847         value->is_typeArray() &&
3848         length <= (juint) value->length()) {
3849       st->print(BULLET"string: ");
3850       java_lang_String::print(obj, st);
3851       st->cr();
3852     }
3853   }
3854 
3855   st->print_cr(BULLET"---- fields (total size %zu words):", oop_size(obj, obj->mark()));
3856   FieldPrinter print_field(st, obj);
3857   print_nonstatic_fields(&print_field);
3858 
3859   if (this == vmClasses::Class_klass()) {
3860     st->print(BULLET"signature: ");
3861     java_lang_Class::print_signature(obj, st);
3862     st->cr();
3863     Klass* real_klass = java_lang_Class::as_Klass(obj);
3864     if (real_klass != nullptr && real_klass->is_instance_klass()) {
3865       st->print_cr(BULLET"---- static fields (%d):", java_lang_Class::static_oop_field_count(obj));
3866       InstanceKlass::cast(real_klass)->do_local_static_fields(&print_field);
3867     }
3868   } else if (this == vmClasses::MethodType_klass()) {
3869     st->print(BULLET"signature: ");
3870     java_lang_invoke_MethodType::print_signature(obj, st);
3871     st->cr();
3872   }
3873 }
3874 
3875 #ifndef PRODUCT
3876 
3877 bool InstanceKlass::verify_itable_index(int i) {
3878   int method_count = klassItable::method_count_for_interface(this);
3879   assert(i >= 0 && i < method_count, "index out of bounds");
3880   return true;
3881 }
3882 
3883 #endif //PRODUCT
3884 
3885 void InstanceKlass::oop_print_value_on(oop obj, outputStream* st) {
3886   st->print("a ");
3887   name()->print_value_on(st);
3888   obj->print_address_on(st);
3889   if (this == vmClasses::String_klass()
3890       && java_lang_String::value(obj) != nullptr) {
3891     ResourceMark rm;
3892     int len = java_lang_String::length(obj);
3893     int plen = (len < 24 ? len : 12);
3894     char* str = java_lang_String::as_utf8_string(obj, 0, plen);
3895     st->print(" = \"%s\"", str);
3896     if (len > plen)
3897       st->print("...[%d]", len);
3898   } else if (this == vmClasses::Class_klass()) {
3899     Klass* k = java_lang_Class::as_Klass(obj);
3900     st->print(" = ");
3901     if (k != nullptr) {
3902       k->print_value_on(st);
3903     } else {
3904       const char* tname = type2name(java_lang_Class::primitive_type(obj));
3905       st->print("%s", tname ? tname : "type?");
3906     }
3907   } else if (this == vmClasses::MethodType_klass()) {
3908     st->print(" = ");
3909     java_lang_invoke_MethodType::print_signature(obj, st);
3910   } else if (java_lang_boxing_object::is_instance(obj)) {
3911     st->print(" = ");
3912     java_lang_boxing_object::print(obj, st);
3913   } else if (this == vmClasses::LambdaForm_klass()) {
3914     oop vmentry = java_lang_invoke_LambdaForm::vmentry(obj);
3915     if (vmentry != nullptr) {
3916       st->print(" => ");
3917       vmentry->print_value_on(st);
3918     }
3919   } else if (this == vmClasses::MemberName_klass()) {
3920     Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(obj);
3921     if (vmtarget != nullptr) {
3922       st->print(" = ");
3923       vmtarget->print_value_on(st);
3924     } else {
3925       oop clazz = java_lang_invoke_MemberName::clazz(obj);
3926       oop name  = java_lang_invoke_MemberName::name(obj);
3927       if (clazz != nullptr) {
3928         clazz->print_value_on(st);
3929       } else {
3930         st->print("null");
3931       }
3932       st->print(".");
3933       if (name != nullptr) {
3934         name->print_value_on(st);
3935       } else {
3936         st->print("null");
3937       }
3938     }
3939   }
3940 }
3941 
3942 const char* InstanceKlass::internal_name() const {
3943   return external_name();
3944 }
3945 
3946 void InstanceKlass::print_class_load_logging(ClassLoaderData* loader_data,
3947                                              const ModuleEntry* module_entry,
3948                                              const ClassFileStream* cfs) const {
3949 
3950   if (ClassListWriter::is_enabled()) {
3951     ClassListWriter::write(this, cfs);
3952   }
3953 
3954   print_class_load_helper(loader_data, module_entry, cfs);
3955   print_class_load_cause_logging();
3956 }
3957 
3958 void InstanceKlass::print_class_load_helper(ClassLoaderData* loader_data,
3959                                              const ModuleEntry* module_entry,
3960                                              const ClassFileStream* cfs) const {
3961 
3962   if (!log_is_enabled(Info, class, load)) {
3963     return;
3964   }
3965 
3966   ResourceMark rm;
3967   LogMessage(class, load) msg;
3968   stringStream info_stream;
3969 
3970   // Name and class hierarchy info
3971   info_stream.print("%s", external_name());
3972 
3973   // Source
3974   if (cfs != nullptr) {
3975     if (cfs->source() != nullptr) {
3976       const char* module_name = (module_entry->name() == nullptr) ? UNNAMED_MODULE : module_entry->name()->as_C_string();
3977       if (module_name != nullptr) {
3978         // When the boot loader created the stream, it didn't know the module name
3979         // yet. Let's format it now.
3980         if (cfs->from_boot_loader_modules_image()) {
3981           info_stream.print(" source: jrt:/%s", module_name);
3982         } else {
3983           info_stream.print(" source: %s", cfs->source());
3984         }
3985       } else {
3986         info_stream.print(" source: %s", cfs->source());
3987       }
3988     } else if (loader_data == ClassLoaderData::the_null_class_loader_data()) {
3989       Thread* current = Thread::current();
3990       Klass* caller = current->is_Java_thread() ?
3991         JavaThread::cast(current)->security_get_caller_class(1):
3992         nullptr;
3993       // caller can be null, for example, during a JVMTI VM_Init hook
3994       if (caller != nullptr) {
3995         info_stream.print(" source: instance of %s", caller->external_name());
3996       } else {
3997         // source is unknown
3998       }
3999     } else {
4000       oop class_loader = loader_data->class_loader();
4001       info_stream.print(" source: %s", class_loader->klass()->external_name());
4002     }
4003   } else {
4004     assert(this->in_aot_cache(), "must be");
4005     if (AOTMetaspace::in_aot_cache_dynamic_region((void*)this)) {
4006       info_stream.print(" source: shared objects file (top)");
4007     } else {
4008       info_stream.print(" source: shared objects file");
4009     }
4010   }
4011 
4012   msg.info("%s", info_stream.as_string());
4013 
4014   if (log_is_enabled(Debug, class, load)) {
4015     stringStream debug_stream;
4016 
4017     // Class hierarchy info
4018     debug_stream.print(" klass: " PTR_FORMAT " super: " PTR_FORMAT,
4019                        p2i(this),  p2i(super()));
4020 
4021     // Interfaces
4022     if (local_interfaces() != nullptr && local_interfaces()->length() > 0) {
4023       debug_stream.print(" interfaces:");
4024       int length = local_interfaces()->length();
4025       for (int i = 0; i < length; i++) {
4026         debug_stream.print(" " PTR_FORMAT,
4027                            p2i(local_interfaces()->at(i)));
4028       }
4029     }
4030 
4031     // Class loader
4032     debug_stream.print(" loader: [");
4033     loader_data->print_value_on(&debug_stream);
4034     debug_stream.print("]");
4035 
4036     // Classfile checksum
4037     if (cfs) {
4038       debug_stream.print(" bytes: %d checksum: %08x",
4039                          cfs->length(),
4040                          ClassLoader::crc32(0, (const char*)cfs->buffer(),
4041                          cfs->length()));
4042     }
4043 
4044     msg.debug("%s", debug_stream.as_string());
4045   }
4046 }
4047 
4048 void InstanceKlass::print_class_load_cause_logging() const {
4049   bool log_cause_native = log_is_enabled(Info, class, load, cause, native);
4050   if (log_cause_native || log_is_enabled(Info, class, load, cause)) {
4051     JavaThread* current = JavaThread::current();
4052     ResourceMark rm(current);
4053     const char* name = external_name();
4054 
4055     if (LogClassLoadingCauseFor == nullptr ||
4056         (strcmp("*", LogClassLoadingCauseFor) != 0 &&
4057          strstr(name, LogClassLoadingCauseFor) == nullptr)) {
4058         return;
4059     }
4060 
4061     // Log Java stack first
4062     {
4063       LogMessage(class, load, cause) msg;
4064       NonInterleavingLogStream info_stream{LogLevelType::Info, msg};
4065 
4066       info_stream.print_cr("Java stack when loading %s:", name);
4067       current->print_stack_on(&info_stream);
4068     }
4069 
4070     // Log native stack second
4071     if (log_cause_native) {
4072       // Log to string first so that lines can be indented
4073       stringStream stack_stream;
4074       char buf[O_BUFLEN];
4075       address lastpc = nullptr;
4076       NativeStackPrinter nsp(current);
4077       nsp.print_stack(&stack_stream, buf, sizeof(buf), lastpc,
4078                       true /* print_source_info */, -1 /* max stack */);
4079 
4080       LogMessage(class, load, cause, native) msg;
4081       NonInterleavingLogStream info_stream{LogLevelType::Info, msg};
4082       info_stream.print_cr("Native stack when loading %s:", name);
4083 
4084       // Print each native stack line to the log
4085       int size = (int) stack_stream.size();
4086       char* stack = stack_stream.as_string();
4087       char* stack_end = stack + size;
4088       char* line_start = stack;
4089       for (char* p = stack; p < stack_end; p++) {
4090         if (*p == '\n') {
4091           *p = '\0';
4092           info_stream.print_cr("\t%s", line_start);
4093           line_start = p + 1;
4094         }
4095       }
4096       if (line_start < stack_end) {
4097         info_stream.print_cr("\t%s", line_start);
4098       }
4099     }
4100   }
4101 }
4102 
4103 // Verification
4104 
4105 class VerifyFieldClosure: public BasicOopIterateClosure {
4106  protected:
4107   template <class T> void do_oop_work(T* p) {
4108     oop obj = RawAccess<>::oop_load(p);
4109     if (!oopDesc::is_oop_or_null(obj)) {
4110       tty->print_cr("Failed: " PTR_FORMAT " -> " PTR_FORMAT, p2i(p), p2i(obj));
4111       Universe::print_on(tty);
4112       guarantee(false, "boom");
4113     }
4114   }
4115  public:
4116   virtual void do_oop(oop* p)       { VerifyFieldClosure::do_oop_work(p); }
4117   virtual void do_oop(narrowOop* p) { VerifyFieldClosure::do_oop_work(p); }
4118 };
4119 
4120 void InstanceKlass::verify_on(outputStream* st) {
4121 #ifndef PRODUCT
4122   // Avoid redundant verifies, this really should be in product.
4123   if (_verify_count == Universe::verify_count()) return;
4124   _verify_count = Universe::verify_count();
4125 #endif
4126 
4127   // Verify Klass
4128   Klass::verify_on(st);
4129 
4130   // Verify that klass is present in ClassLoaderData
4131   guarantee(class_loader_data()->contains_klass(this),
4132             "this class isn't found in class loader data");
4133 
4134   // Verify vtables
4135   if (is_linked()) {
4136     // $$$ This used to be done only for m/s collections.  Doing it
4137     // always seemed a valid generalization.  (DLD -- 6/00)
4138     vtable().verify(st);
4139   }
4140 
4141   // Verify first subklass
4142   if (subklass() != nullptr) {
4143     guarantee(subklass()->is_klass(), "should be klass");
4144   }
4145 
4146   // Verify siblings
4147   Klass* super = this->super();
4148   Klass* sib = next_sibling();
4149   if (sib != nullptr) {
4150     if (sib == this) {
4151       fatal("subclass points to itself " PTR_FORMAT, p2i(sib));
4152     }
4153 
4154     guarantee(sib->is_klass(), "should be klass");
4155     guarantee(sib->super() == super, "siblings should have same superklass");
4156   }
4157 
4158   // Verify local interfaces
4159   if (local_interfaces()) {
4160     Array<InstanceKlass*>* local_interfaces = this->local_interfaces();
4161     for (int j = 0; j < local_interfaces->length(); j++) {
4162       InstanceKlass* e = local_interfaces->at(j);
4163       guarantee(e->is_klass() && e->is_interface(), "invalid local interface");
4164     }
4165   }
4166 
4167   // Verify transitive interfaces
4168   if (transitive_interfaces() != nullptr) {
4169     Array<InstanceKlass*>* transitive_interfaces = this->transitive_interfaces();
4170     for (int j = 0; j < transitive_interfaces->length(); j++) {
4171       InstanceKlass* e = transitive_interfaces->at(j);
4172       guarantee(e->is_klass() && e->is_interface(), "invalid transitive interface");
4173     }
4174   }
4175 
4176   // Verify methods
4177   if (methods() != nullptr) {
4178     Array<Method*>* methods = this->methods();
4179     for (int j = 0; j < methods->length(); j++) {
4180       guarantee(methods->at(j)->is_method(), "non-method in methods array");
4181     }
4182     for (int j = 0; j < methods->length() - 1; j++) {
4183       Method* m1 = methods->at(j);
4184       Method* m2 = methods->at(j + 1);
4185       guarantee(m1->name()->fast_compare(m2->name()) <= 0, "methods not sorted correctly");
4186     }
4187   }
4188 
4189   // Verify method ordering
4190   if (method_ordering() != nullptr) {
4191     Array<int>* method_ordering = this->method_ordering();
4192     int length = method_ordering->length();
4193     if (JvmtiExport::can_maintain_original_method_order() ||
4194         ((CDSConfig::is_using_archive() || CDSConfig::is_dumping_archive()) && length != 0)) {
4195       guarantee(length == methods()->length(), "invalid method ordering length");
4196       jlong sum = 0;
4197       for (int j = 0; j < length; j++) {
4198         int original_index = method_ordering->at(j);
4199         guarantee(original_index >= 0, "invalid method ordering index");
4200         guarantee(original_index < length, "invalid method ordering index");
4201         sum += original_index;
4202       }
4203       // Verify sum of indices 0,1,...,length-1
4204       guarantee(sum == ((jlong)length*(length-1))/2, "invalid method ordering sum");
4205     } else {
4206       guarantee(length == 0, "invalid method ordering length");
4207     }
4208   }
4209 
4210   // Verify default methods
4211   if (default_methods() != nullptr) {
4212     Array<Method*>* methods = this->default_methods();
4213     for (int j = 0; j < methods->length(); j++) {
4214       guarantee(methods->at(j)->is_method(), "non-method in methods array");
4215     }
4216     for (int j = 0; j < methods->length() - 1; j++) {
4217       Method* m1 = methods->at(j);
4218       Method* m2 = methods->at(j + 1);
4219       guarantee(m1->name()->fast_compare(m2->name()) <= 0, "methods not sorted correctly");
4220     }
4221   }
4222 
4223   // Verify JNI static field identifiers
4224   if (jni_ids() != nullptr) {
4225     jni_ids()->verify(this);
4226   }
4227 
4228   // Verify other fields
4229   if (constants() != nullptr) {
4230     guarantee(constants()->is_constantPool(), "should be constant pool");
4231   }
4232 }
4233 
4234 void InstanceKlass::oop_verify_on(oop obj, outputStream* st) {
4235   Klass::oop_verify_on(obj, st);
4236   VerifyFieldClosure blk;
4237   obj->oop_iterate(&blk);
4238 }
4239 
4240 // JNIid class for jfieldIDs only
4241 // Note to reviewers:
4242 // These JNI functions are just moved over to column 1 and not changed
4243 // in the compressed oops workspace.
4244 JNIid::JNIid(InstanceKlass* holder, int offset, JNIid* next) {
4245   _holder = holder;
4246   _offset = offset;
4247   _next = next;
4248   DEBUG_ONLY(_is_static_field_id = false;)
4249 }
4250 
4251 JNIid* JNIid::find(int offset) {
4252   JNIid* current = this;
4253   while (current != nullptr) {
4254     if (current->offset() == offset) return current;
4255     current = current->next();
4256   }
4257   return nullptr;
4258 }
4259 
4260 void JNIid::deallocate(JNIid* current) {
4261   while (current != nullptr) {
4262     JNIid* next = current->next();
4263     delete current;
4264     current = next;
4265   }
4266 }
4267 
4268 void JNIid::verify(InstanceKlass* holder) {
4269   int first_field_offset  = InstanceMirrorKlass::offset_of_static_fields();
4270   int end_field_offset;
4271   end_field_offset = first_field_offset + (holder->static_field_size() * wordSize);
4272 
4273   JNIid* current = this;
4274   while (current != nullptr) {
4275     guarantee(current->holder() == holder, "Invalid klass in JNIid");
4276 #ifdef ASSERT
4277     int o = current->offset();
4278     if (current->is_static_field_id()) {
4279       guarantee(o >= first_field_offset  && o < end_field_offset,  "Invalid static field offset in JNIid");
4280     }
4281 #endif
4282     current = current->next();
4283   }
4284 }
4285 
4286 void InstanceKlass::set_init_state(ClassState state) {
4287 #ifdef ASSERT
4288   bool good_state = in_aot_cache() ? (_init_state <= state)
4289                                                : (_init_state < state);
4290   assert(good_state || state == allocated, "illegal state transition");
4291 #endif
4292   assert(_init_thread == nullptr, "should be cleared before state change");
4293   AtomicAccess::release_store(&_init_state, state);
4294 }
4295 
4296 #if INCLUDE_JVMTI
4297 
4298 // RedefineClasses() support for previous versions
4299 
4300 // Globally, there is at least one previous version of a class to walk
4301 // during class unloading, which is saved because old methods in the class
4302 // are still running.   Otherwise the previous version list is cleaned up.
4303 bool InstanceKlass::_should_clean_previous_versions = false;
4304 
4305 // Returns true if there are previous versions of a class for class
4306 // unloading only. Also resets the flag to false. purge_previous_version
4307 // will set the flag to true if there are any left, i.e., if there's any
4308 // work to do for next time. This is to avoid the expensive code cache
4309 // walk in CLDG::clean_deallocate_lists().
4310 bool InstanceKlass::should_clean_previous_versions_and_reset() {
4311   bool ret = _should_clean_previous_versions;
4312   log_trace(redefine, class, iklass, purge)("Class unloading: should_clean_previous_versions = %s",
4313      ret ? "true" : "false");
4314   _should_clean_previous_versions = false;
4315   return ret;
4316 }
4317 
4318 // This nulls out the jmethodID for all obsolete methods in the previous version of the 'klass'.
4319 // These obsolete methods only exist in the previous version and we're about to delete the memory for them.
4320 // The jmethodID for these are deallocated when we unload the class, so this doesn't remove them from the table.
4321 void InstanceKlass::clear_obsolete_jmethod_ids(InstanceKlass* klass) {
4322   Array<Method*>* method_refs = klass->methods();
4323   for (int k = 0; k < method_refs->length(); k++) {
4324     Method* method = method_refs->at(k);
4325     // Only need to clear obsolete methods.
4326     if (method != nullptr && method->is_obsolete()) {
4327       method->clear_jmethod_id();
4328     }
4329   }
4330 }
4331 
4332 // Purge previous versions before adding new previous versions of the class and
4333 // during class unloading.
4334 void InstanceKlass::purge_previous_version_list() {
4335   assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
4336   assert(has_been_redefined(), "Should only be called for main class");
4337 
4338   // Quick exit.
4339   if (previous_versions() == nullptr) {
4340     return;
4341   }
4342 
4343   // This klass has previous versions so see what we can cleanup
4344   // while it is safe to do so.
4345 
4346   int deleted_count = 0;    // leave debugging breadcrumbs
4347   int live_count = 0;
4348   ClassLoaderData* loader_data = class_loader_data();
4349   assert(loader_data != nullptr, "should never be null");
4350 
4351   ResourceMark rm;
4352   log_trace(redefine, class, iklass, purge)("%s: previous versions", external_name());
4353 
4354   // previous versions are linked together through the InstanceKlass
4355   InstanceKlass* pv_node = previous_versions();
4356   InstanceKlass* last = this;
4357   int version = 0;
4358 
4359   // check the previous versions list
4360   for (; pv_node != nullptr; ) {
4361 
4362     ConstantPool* pvcp = pv_node->constants();
4363     assert(pvcp != nullptr, "cp ref was unexpectedly cleared");
4364 
4365     if (!pvcp->on_stack()) {
4366       // If the constant pool isn't on stack, none of the methods
4367       // are executing.  Unlink this previous_version.
4368       // The previous version InstanceKlass is on the ClassLoaderData deallocate list
4369       // so will be deallocated during the next phase of class unloading.
4370       log_trace(redefine, class, iklass, purge)
4371         ("previous version " PTR_FORMAT " is dead.", p2i(pv_node));
4372       // Unlink from previous version list.
4373       assert(pv_node->class_loader_data() == loader_data, "wrong loader_data");
4374       InstanceKlass* next = pv_node->previous_versions();
4375       clear_obsolete_jmethod_ids(pv_node); // jmethodID maintenance for the unloaded class
4376       pv_node->link_previous_versions(nullptr);   // point next to null
4377       last->link_previous_versions(next);
4378       // Delete this node directly. Nothing is referring to it and we don't
4379       // want it to increase the counter for metadata to delete in CLDG.
4380       MetadataFactory::free_metadata(loader_data, pv_node);
4381       pv_node = next;
4382       deleted_count++;
4383       version++;
4384       continue;
4385     } else {
4386       assert(pvcp->pool_holder() != nullptr, "Constant pool with no holder");
4387       guarantee (!loader_data->is_unloading(), "unloaded classes can't be on the stack");
4388       live_count++;
4389       if (pvcp->in_aot_cache()) {
4390         // Shared previous versions can never be removed so no cleaning is needed.
4391         log_trace(redefine, class, iklass, purge)("previous version " PTR_FORMAT " is shared", p2i(pv_node));
4392       } else {
4393         // Previous version alive, set that clean is needed for next time.
4394         _should_clean_previous_versions = true;
4395         log_trace(redefine, class, iklass, purge)("previous version " PTR_FORMAT " is alive", p2i(pv_node));
4396       }
4397     }
4398 
4399     // next previous version
4400     last = pv_node;
4401     pv_node = pv_node->previous_versions();
4402     version++;
4403   }
4404   log_trace(redefine, class, iklass, purge)
4405     ("previous version stats: live=%d, deleted=%d", live_count, deleted_count);
4406 }
4407 
4408 void InstanceKlass::mark_newly_obsolete_methods(Array<Method*>* old_methods,
4409                                                 int emcp_method_count) {
4410   int obsolete_method_count = old_methods->length() - emcp_method_count;
4411 
4412   if (emcp_method_count != 0 && obsolete_method_count != 0 &&
4413       _previous_versions != nullptr) {
4414     // We have a mix of obsolete and EMCP methods so we have to
4415     // clear out any matching EMCP method entries the hard way.
4416     int local_count = 0;
4417     for (int i = 0; i < old_methods->length(); i++) {
4418       Method* old_method = old_methods->at(i);
4419       if (old_method->is_obsolete()) {
4420         // only obsolete methods are interesting
4421         Symbol* m_name = old_method->name();
4422         Symbol* m_signature = old_method->signature();
4423 
4424         // previous versions are linked together through the InstanceKlass
4425         int j = 0;
4426         for (InstanceKlass* prev_version = _previous_versions;
4427              prev_version != nullptr;
4428              prev_version = prev_version->previous_versions(), j++) {
4429 
4430           Array<Method*>* method_refs = prev_version->methods();
4431           for (int k = 0; k < method_refs->length(); k++) {
4432             Method* method = method_refs->at(k);
4433 
4434             if (!method->is_obsolete() &&
4435                 method->name() == m_name &&
4436                 method->signature() == m_signature) {
4437               // The current RedefineClasses() call has made all EMCP
4438               // versions of this method obsolete so mark it as obsolete
4439               log_trace(redefine, class, iklass, add)
4440                 ("%s(%s): flush obsolete method @%d in version @%d",
4441                  m_name->as_C_string(), m_signature->as_C_string(), k, j);
4442 
4443               method->set_is_obsolete();
4444               break;
4445             }
4446           }
4447 
4448           // The previous loop may not find a matching EMCP method, but
4449           // that doesn't mean that we can optimize and not go any
4450           // further back in the PreviousVersion generations. The EMCP
4451           // method for this generation could have already been made obsolete,
4452           // but there still may be an older EMCP method that has not
4453           // been made obsolete.
4454         }
4455 
4456         if (++local_count >= obsolete_method_count) {
4457           // no more obsolete methods so bail out now
4458           break;
4459         }
4460       }
4461     }
4462   }
4463 }
4464 
4465 // Save the scratch_class as the previous version if any of the methods are running.
4466 // The previous_versions are used to set breakpoints in EMCP methods and they are
4467 // also used to clean MethodData links to redefined methods that are no longer running.
4468 void InstanceKlass::add_previous_version(InstanceKlass* scratch_class,
4469                                          int emcp_method_count) {
4470   assert(Thread::current()->is_VM_thread(),
4471          "only VMThread can add previous versions");
4472 
4473   ResourceMark rm;
4474   log_trace(redefine, class, iklass, add)
4475     ("adding previous version ref for %s, EMCP_cnt=%d", scratch_class->external_name(), emcp_method_count);
4476 
4477   // Clean out old previous versions for this class
4478   purge_previous_version_list();
4479 
4480   // Mark newly obsolete methods in remaining previous versions.  An EMCP method from
4481   // a previous redefinition may be made obsolete by this redefinition.
4482   Array<Method*>* old_methods = scratch_class->methods();
4483   mark_newly_obsolete_methods(old_methods, emcp_method_count);
4484 
4485   // If the constant pool for this previous version of the class
4486   // is not marked as being on the stack, then none of the methods
4487   // in this previous version of the class are on the stack so
4488   // we don't need to add this as a previous version.
4489   ConstantPool* cp_ref = scratch_class->constants();
4490   if (!cp_ref->on_stack()) {
4491     log_trace(redefine, class, iklass, add)("scratch class not added; no methods are running");
4492     scratch_class->class_loader_data()->add_to_deallocate_list(scratch_class);
4493     return;
4494   }
4495 
4496   // Add previous version if any methods are still running or if this is
4497   // a shared class which should never be removed.
4498   assert(scratch_class->previous_versions() == nullptr, "shouldn't have a previous version");
4499   scratch_class->link_previous_versions(previous_versions());
4500   link_previous_versions(scratch_class);
4501   if (cp_ref->in_aot_cache()) {
4502     log_trace(redefine, class, iklass, add) ("scratch class added; class is shared");
4503   } else {
4504     //  We only set clean_previous_versions flag for processing during class
4505     // unloading for non-shared classes.
4506     _should_clean_previous_versions = true;
4507     log_trace(redefine, class, iklass, add) ("scratch class added; one of its methods is on_stack.");
4508   }
4509 } // end add_previous_version()
4510 
4511 #endif // INCLUDE_JVMTI
4512 
4513 Method* InstanceKlass::method_with_idnum(int idnum) const {
4514   Method* m = nullptr;
4515   if (idnum < methods()->length()) {
4516     m = methods()->at(idnum);
4517   }
4518   if (m == nullptr || m->method_idnum() != idnum) {
4519     for (int index = 0; index < methods()->length(); ++index) {
4520       m = methods()->at(index);
4521       if (m->method_idnum() == idnum) {
4522         return m;
4523       }
4524     }
4525     // None found, return null for the caller to handle.
4526     return nullptr;
4527   }
4528   return m;
4529 }
4530 
4531 
4532 Method* InstanceKlass::method_with_orig_idnum(int idnum) const {
4533   if (idnum >= methods()->length()) {
4534     return nullptr;
4535   }
4536   Method* m = methods()->at(idnum);
4537   if (m != nullptr && m->orig_method_idnum() == idnum) {
4538     return m;
4539   }
4540   // Obsolete method idnum does not match the original idnum
4541   for (int index = 0; index < methods()->length(); ++index) {
4542     m = methods()->at(index);
4543     if (m->orig_method_idnum() == idnum) {
4544       return m;
4545     }
4546   }
4547   // None found, return null for the caller to handle.
4548   return nullptr;
4549 }
4550 
4551 
4552 Method* InstanceKlass::method_with_orig_idnum(int idnum, int version) const {
4553   const InstanceKlass* holder = get_klass_version(version);
4554   if (holder == nullptr) {
4555     return nullptr; // The version of klass is gone, no method is found
4556   }
4557   return holder->method_with_orig_idnum(idnum);
4558 }
4559 
4560 #if INCLUDE_JVMTI
4561 JvmtiCachedClassFileData* InstanceKlass::get_cached_class_file() {
4562   return _cached_class_file;
4563 }
4564 
4565 jint InstanceKlass::get_cached_class_file_len() {
4566   return VM_RedefineClasses::get_cached_class_file_len(_cached_class_file);
4567 }
4568 
4569 unsigned char * InstanceKlass::get_cached_class_file_bytes() {
4570   return VM_RedefineClasses::get_cached_class_file_bytes(_cached_class_file);
4571 }
4572 #endif
4573 
4574 // Make a step iterating over the class hierarchy under the root class.
4575 // Skips subclasses if requested.
4576 void ClassHierarchyIterator::next() {
4577   assert(_current != nullptr, "required");
4578   if (_visit_subclasses && _current->subklass() != nullptr) {
4579     _current = _current->subklass();
4580     return; // visit next subclass
4581   }
4582   _visit_subclasses = true; // reset
4583   while (_current->next_sibling() == nullptr && _current != _root) {
4584     _current = _current->java_super(); // backtrack; no more sibling subclasses left
4585   }
4586   if (_current == _root) {
4587     // Iteration is over (back at root after backtracking). Invalidate the iterator.
4588     _current = nullptr;
4589     return;
4590   }
4591   _current = _current->next_sibling();
4592   return; // visit next sibling subclass
4593 }