1 /*
   2  * Copyright (c) 2018, 2025, 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/aotArtifactFinder.hpp"
  26 #include "cds/aotClassInitializer.hpp"
  27 #include "cds/aotClassLocation.hpp"
  28 #include "cds/aotLogging.hpp"
  29 #include "cds/aotReferenceObjSupport.hpp"
  30 #include "cds/archiveBuilder.hpp"
  31 #include "cds/archiveHeapLoader.hpp"
  32 #include "cds/archiveHeapWriter.hpp"
  33 #include "cds/archiveUtils.hpp"
  34 #include "cds/cdsConfig.hpp"
  35 #include "cds/cdsEnumKlass.hpp"
  36 #include "cds/cdsHeapVerifier.hpp"
  37 #include "cds/heapShared.hpp"
  38 #include "cds/metaspaceShared.hpp"
  39 #include "cds/regeneratedClasses.hpp"
  40 #include "classfile/classLoaderData.hpp"
  41 #include "classfile/javaClasses.inline.hpp"
  42 #include "classfile/modules.hpp"
  43 #include "classfile/stringTable.hpp"
  44 #include "classfile/symbolTable.hpp"
  45 #include "classfile/systemDictionary.hpp"
  46 #include "classfile/systemDictionaryShared.hpp"
  47 #include "classfile/vmClasses.hpp"
  48 #include "classfile/vmSymbols.hpp"
  49 #include "gc/shared/collectedHeap.hpp"
  50 #include "gc/shared/gcLocker.hpp"
  51 #include "gc/shared/gcVMOperations.hpp"
  52 #include "logging/log.hpp"
  53 #include "logging/logStream.hpp"
  54 #include "memory/iterator.inline.hpp"
  55 #include "memory/resourceArea.hpp"
  56 #include "memory/universe.hpp"
  57 #include "oops/compressedOops.inline.hpp"
  58 #include "oops/fieldStreams.inline.hpp"
  59 #include "oops/objArrayOop.inline.hpp"
  60 #include "oops/oop.inline.hpp"
  61 #include "oops/typeArrayOop.inline.hpp"
  62 #include "prims/jvmtiExport.hpp"
  63 #include "runtime/arguments.hpp"
  64 #include "runtime/fieldDescriptor.inline.hpp"
  65 #include "runtime/init.hpp"
  66 #include "runtime/javaCalls.hpp"
  67 #include "runtime/mutexLocker.hpp"
  68 #include "runtime/safepointVerifiers.hpp"
  69 #include "utilities/bitMap.inline.hpp"
  70 #include "utilities/copy.hpp"
  71 #if INCLUDE_G1GC
  72 #include "gc/g1/g1CollectedHeap.hpp"
  73 #endif
  74 
  75 #if INCLUDE_CDS_JAVA_HEAP
  76 
  77 struct ArchivableStaticFieldInfo {
  78   const char* klass_name;
  79   const char* field_name;
  80   InstanceKlass* klass;
  81   int offset;
  82   BasicType type;
  83 
  84   ArchivableStaticFieldInfo(const char* k, const char* f)
  85   : klass_name(k), field_name(f), klass(nullptr), offset(0), type(T_ILLEGAL) {}
  86 
  87   bool valid() {
  88     return klass_name != nullptr;
  89   }
  90 };
  91 
  92 DumpedInternedStrings *HeapShared::_dumped_interned_strings = nullptr;
  93 
  94 size_t HeapShared::_alloc_count[HeapShared::ALLOC_STAT_SLOTS];
  95 size_t HeapShared::_alloc_size[HeapShared::ALLOC_STAT_SLOTS];
  96 size_t HeapShared::_total_obj_count;
  97 size_t HeapShared::_total_obj_size;
  98 
  99 #ifndef PRODUCT
 100 #define ARCHIVE_TEST_FIELD_NAME "archivedObjects"
 101 static Array<char>* _archived_ArchiveHeapTestClass = nullptr;
 102 static const char* _test_class_name = nullptr;
 103 static Klass* _test_class = nullptr;
 104 static const ArchivedKlassSubGraphInfoRecord* _test_class_record = nullptr;
 105 #endif
 106 
 107 
 108 //
 109 // If you add new entries to the following tables, you should know what you're doing!
 110 //
 111 
 112 static ArchivableStaticFieldInfo archive_subgraph_entry_fields[] = {
 113   {"java/lang/Integer$IntegerCache",              "archivedCache"},
 114   {"java/lang/Long$LongCache",                    "archivedCache"},
 115   {"java/lang/Byte$ByteCache",                    "archivedCache"},
 116   {"java/lang/Short$ShortCache",                  "archivedCache"},
 117   {"java/lang/Character$CharacterCache",          "archivedCache"},
 118   {"java/util/jar/Attributes$Name",               "KNOWN_NAMES"},
 119   {"sun/util/locale/BaseLocale",                  "constantBaseLocales"},
 120   {"jdk/internal/module/ArchivedModuleGraph",     "archivedModuleGraph"},
 121   {"java/util/ImmutableCollections",              "archivedObjects"},
 122   {"java/lang/ModuleLayer",                       "EMPTY_LAYER"},
 123   {"java/lang/module/Configuration",              "EMPTY_CONFIGURATION"},
 124   {"jdk/internal/math/FDBigInteger",              "archivedCaches"},
 125 
 126 #ifndef PRODUCT
 127   {nullptr, nullptr}, // Extra slot for -XX:ArchiveHeapTestClass
 128 #endif
 129   {nullptr, nullptr},
 130 };
 131 
 132 // full module graph
 133 static ArchivableStaticFieldInfo fmg_archive_subgraph_entry_fields[] = {
 134   {"jdk/internal/loader/ArchivedClassLoaders",    "archivedClassLoaders"},
 135   {ARCHIVED_BOOT_LAYER_CLASS,                     ARCHIVED_BOOT_LAYER_FIELD},
 136   {"java/lang/Module$ArchivedData",               "archivedData"},
 137   {nullptr, nullptr},
 138 };
 139 
 140 KlassSubGraphInfo* HeapShared::_dump_time_special_subgraph;
 141 ArchivedKlassSubGraphInfoRecord* HeapShared::_run_time_special_subgraph;
 142 GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = nullptr;
 143 GrowableArrayCHeap<OopHandle, mtClassShared>* HeapShared::_root_segments = nullptr;
 144 int HeapShared::_root_segment_max_size_elems;
 145 OopHandle HeapShared::_scratch_basic_type_mirrors[T_VOID+1];
 146 MetaspaceObjToOopHandleTable* HeapShared::_scratch_objects_table = nullptr;
 147 
 148 static bool is_subgraph_root_class_of(ArchivableStaticFieldInfo fields[], InstanceKlass* ik) {
 149   for (int i = 0; fields[i].valid(); i++) {
 150     if (fields[i].klass == ik) {
 151       return true;
 152     }
 153   }
 154   return false;
 155 }
 156 
 157 bool HeapShared::is_subgraph_root_class(InstanceKlass* ik) {
 158   return is_subgraph_root_class_of(archive_subgraph_entry_fields, ik) ||
 159          is_subgraph_root_class_of(fmg_archive_subgraph_entry_fields, ik);
 160 }
 161 
 162 unsigned HeapShared::oop_hash(oop const& p) {
 163   // Do not call p->identity_hash() as that will update the
 164   // object header.
 165   return primitive_hash(cast_from_oop<intptr_t>(p));
 166 }
 167 
 168 static void reset_states(oop obj, TRAPS) {
 169   Handle h_obj(THREAD, obj);
 170   InstanceKlass* klass = InstanceKlass::cast(obj->klass());
 171   TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
 172   Symbol* method_sig = vmSymbols::void_method_signature();
 173 
 174   while (klass != nullptr) {
 175     Method* method = klass->find_method(method_name, method_sig);
 176     if (method != nullptr) {
 177       assert(method->is_private(), "must be");
 178       if (log_is_enabled(Debug, aot)) {
 179         ResourceMark rm(THREAD);
 180         log_debug(aot)("  calling %s", method->name_and_sig_as_C_string());
 181       }
 182       JavaValue result(T_VOID);
 183       JavaCalls::call_special(&result, h_obj, klass,
 184                               method_name, method_sig, CHECK);
 185     }
 186     klass = klass->java_super();
 187   }
 188 }
 189 
 190 void HeapShared::reset_archived_object_states(TRAPS) {
 191   assert(CDSConfig::is_dumping_heap(), "dump-time only");
 192   log_debug(aot)("Resetting platform loader");
 193   reset_states(SystemDictionary::java_platform_loader(), CHECK);
 194   log_debug(aot)("Resetting system loader");
 195   reset_states(SystemDictionary::java_system_loader(), CHECK);
 196 
 197   // Clean up jdk.internal.loader.ClassLoaders::bootLoader(), which is not
 198   // directly used for class loading, but rather is used by the core library
 199   // to keep track of resources, etc, loaded by the null class loader.
 200   //
 201   // Note, this object is non-null, and is not the same as
 202   // ClassLoaderData::the_null_class_loader_data()->class_loader(),
 203   // which is null.
 204   log_debug(aot)("Resetting boot loader");
 205   JavaValue result(T_OBJECT);
 206   JavaCalls::call_static(&result,
 207                          vmClasses::jdk_internal_loader_ClassLoaders_klass(),
 208                          vmSymbols::bootLoader_name(),
 209                          vmSymbols::void_BuiltinClassLoader_signature(),
 210                          CHECK);
 211   Handle boot_loader(THREAD, result.get_oop());
 212   reset_states(boot_loader(), CHECK);
 213 }
 214 
 215 HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = nullptr;
 216 
 217 bool HeapShared::has_been_archived(oop obj) {
 218   assert(CDSConfig::is_dumping_heap(), "dump-time only");
 219   return archived_object_cache()->get(obj) != nullptr;
 220 }
 221 
 222 int HeapShared::append_root(oop obj) {
 223   assert(CDSConfig::is_dumping_heap(), "dump-time only");
 224   if (obj != nullptr) {
 225     assert(has_been_archived(obj), "must be");
 226   }
 227   // No GC should happen since we aren't scanning _pending_roots.
 228   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 229 
 230   return _pending_roots->append(obj);
 231 }
 232 
 233 objArrayOop HeapShared::root_segment(int segment_idx) {
 234   if (CDSConfig::is_dumping_heap()) {
 235     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 236   } else {
 237     assert(CDSConfig::is_using_archive(), "must be");
 238   }
 239 
 240   objArrayOop segment = (objArrayOop)_root_segments->at(segment_idx).resolve();
 241   assert(segment != nullptr, "should have been initialized");
 242   return segment;
 243 }
 244 
 245 void HeapShared::get_segment_indexes(int idx, int& seg_idx, int& int_idx) {
 246   assert(_root_segment_max_size_elems > 0, "sanity");
 247 
 248   // Try to avoid divisions for the common case.
 249   if (idx < _root_segment_max_size_elems) {
 250     seg_idx = 0;
 251     int_idx = idx;
 252   } else {
 253     seg_idx = idx / _root_segment_max_size_elems;
 254     int_idx = idx % _root_segment_max_size_elems;
 255   }
 256 
 257   assert(idx == seg_idx * _root_segment_max_size_elems + int_idx,
 258          "sanity: %d index maps to %d segment and %d internal", idx, seg_idx, int_idx);
 259 }
 260 
 261 // Returns an objArray that contains all the roots of the archived objects
 262 oop HeapShared::get_root(int index, bool clear) {
 263   assert(index >= 0, "sanity");
 264   assert(!CDSConfig::is_dumping_heap() && CDSConfig::is_using_archive(), "runtime only");
 265   assert(!_root_segments->is_empty(), "must have loaded shared heap");
 266   int seg_idx, int_idx;
 267   get_segment_indexes(index, seg_idx, int_idx);
 268   oop result = root_segment(seg_idx)->obj_at(int_idx);
 269   if (clear) {
 270     clear_root(index);
 271   }
 272   return result;
 273 }
 274 
 275 void HeapShared::clear_root(int index) {
 276   assert(index >= 0, "sanity");
 277   assert(CDSConfig::is_using_archive(), "must be");
 278   if (ArchiveHeapLoader::is_in_use()) {
 279     int seg_idx, int_idx;
 280     get_segment_indexes(index, seg_idx, int_idx);
 281     if (log_is_enabled(Debug, aot, heap)) {
 282       oop old = root_segment(seg_idx)->obj_at(int_idx);
 283       log_debug(aot, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
 284     }
 285     root_segment(seg_idx)->obj_at_put(int_idx, nullptr);
 286   }
 287 }
 288 
 289 bool HeapShared::archive_object(oop obj, oop referrer, KlassSubGraphInfo* subgraph_info) {
 290   assert(CDSConfig::is_dumping_heap(), "dump-time only");
 291 
 292   assert(!obj->is_stackChunk(), "do not archive stack chunks");
 293   if (has_been_archived(obj)) {
 294     return true;
 295   }
 296 
 297   if (ArchiveHeapWriter::is_too_large_to_archive(obj->size())) {
 298     log_debug(aot, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: %zu",
 299                          p2i(obj), obj->size());
 300     debug_trace();
 301     return false;
 302   } else {
 303     count_allocation(obj->size());
 304     ArchiveHeapWriter::add_source_obj(obj);
 305     CachedOopInfo info = make_cached_oop_info(obj, referrer);
 306     archived_object_cache()->put_when_absent(obj, info);
 307     archived_object_cache()->maybe_grow();
 308     mark_native_pointers(obj);
 309 
 310     Klass* k = obj->klass();
 311     if (k->is_instance_klass()) {
 312       // Whenever we see a non-array Java object of type X, we mark X to be aot-initialized.
 313       // This ensures that during the production run, whenever Java code sees a cached object
 314       // of type X, we know that X is already initialized. (see TODO comment below ...)
 315 
 316       if (InstanceKlass::cast(k)->is_enum_subclass()
 317           // We can't rerun <clinit> of enum classes (see cdsEnumKlass.cpp) so
 318           // we must store them as AOT-initialized.
 319           || (subgraph_info == _dump_time_special_subgraph))
 320           // TODO: we do this only for the special subgraph for now. Extending this to
 321           // other subgraphs would require more refactoring of the core library (such as
 322           // move some initialization logic into runtimeSetup()).
 323           //
 324           // For the other subgraphs, we have a weaker mechanism to ensure that
 325           // all classes in a subgraph are initialized before the subgraph is programmatically
 326           // returned from jdk.internal.misc.CDS::initializeFromArchive().
 327           // See HeapShared::initialize_from_archived_subgraph().
 328       {
 329         AOTArtifactFinder::add_aot_inited_class(InstanceKlass::cast(k));
 330       }
 331 
 332       if (java_lang_Class::is_instance(obj)) {
 333         Klass* mirror_k = java_lang_Class::as_Klass(obj);
 334         if (mirror_k != nullptr) {
 335           AOTArtifactFinder::add_cached_class(mirror_k);
 336         }
 337       } else if (java_lang_invoke_ResolvedMethodName::is_instance(obj)) {
 338         Method* m = java_lang_invoke_ResolvedMethodName::vmtarget(obj);
 339         if (m != nullptr) {
 340           if (RegeneratedClasses::has_been_regenerated(m)) {
 341             m = RegeneratedClasses::get_regenerated_object(m);
 342           }
 343           InstanceKlass* method_holder = m->method_holder();
 344           AOTArtifactFinder::add_cached_class(method_holder);
 345         }
 346       }
 347     }
 348 
 349     if (log_is_enabled(Debug, aot, heap)) {
 350       ResourceMark rm;
 351       LogTarget(Debug, aot, heap) log;
 352       LogStream out(log);
 353       out.print("Archived heap object " PTR_FORMAT " : %s ",
 354                 p2i(obj), obj->klass()->external_name());
 355       if (java_lang_Class::is_instance(obj)) {
 356         Klass* k = java_lang_Class::as_Klass(obj);
 357         if (k != nullptr) {
 358           out.print("%s", k->external_name());
 359         } else {
 360           out.print("primitive");
 361         }
 362       }
 363       out.cr();
 364     }
 365 
 366     return true;
 367   }
 368 }
 369 
 370 class MetaspaceObjToOopHandleTable: public ResourceHashtable<MetaspaceObj*, OopHandle,
 371     36137, // prime number
 372     AnyObj::C_HEAP,
 373     mtClassShared> {
 374 public:
 375   oop get_oop(MetaspaceObj* ptr) {
 376     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 377     OopHandle* handle = get(ptr);
 378     if (handle != nullptr) {
 379       return handle->resolve();
 380     } else {
 381       return nullptr;
 382     }
 383   }
 384   void set_oop(MetaspaceObj* ptr, oop o) {
 385     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 386     OopHandle handle(Universe::vm_global(), o);
 387     bool is_new = put(ptr, handle);
 388     assert(is_new, "cannot set twice");
 389   }
 390   void remove_oop(MetaspaceObj* ptr) {
 391     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 392     OopHandle* handle = get(ptr);
 393     if (handle != nullptr) {
 394       handle->release(Universe::vm_global());
 395       remove(ptr);
 396     }
 397   }
 398 };
 399 
 400 void HeapShared::add_scratch_resolved_references(ConstantPool* src, objArrayOop dest) {
 401   if (SystemDictionaryShared::is_builtin_loader(src->pool_holder()->class_loader_data())) {
 402     _scratch_objects_table->set_oop(src, dest);
 403   }
 404 }
 405 
 406 objArrayOop HeapShared::scratch_resolved_references(ConstantPool* src) {
 407   return (objArrayOop)_scratch_objects_table->get_oop(src);
 408 }
 409 
 410 void HeapShared::init_dumping() {
 411   _scratch_objects_table = new (mtClass)MetaspaceObjToOopHandleTable();
 412   _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
 413 }
 414 
 415 void HeapShared::init_scratch_objects_for_basic_type_mirrors(TRAPS) {
 416   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
 417     BasicType bt = (BasicType)i;
 418     if (!is_reference_type(bt)) {
 419       oop m = java_lang_Class::create_basic_type_mirror(type2name(bt), bt, CHECK);
 420       _scratch_basic_type_mirrors[i] = OopHandle(Universe::vm_global(), m);
 421     }
 422   }
 423 }
 424 
 425 // Given java_mirror that represents a (primitive or reference) type T,
 426 // return the "scratch" version that represents the same type T.
 427 // Note that if java_mirror will be returned if it's already a
 428 // scratch mirror.
 429 //
 430 // See java_lang_Class::create_scratch_mirror() for more info.
 431 oop HeapShared::scratch_java_mirror(oop java_mirror) {
 432   assert(java_lang_Class::is_instance(java_mirror), "must be");
 433 
 434   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
 435     BasicType bt = (BasicType)i;
 436     if (!is_reference_type(bt)) {
 437       if (_scratch_basic_type_mirrors[i].resolve() == java_mirror) {
 438         return java_mirror;
 439       }
 440     }
 441   }
 442 
 443   if (java_lang_Class::is_primitive(java_mirror)) {
 444     return scratch_java_mirror(java_lang_Class::as_BasicType(java_mirror));
 445   } else {
 446     return scratch_java_mirror(java_lang_Class::as_Klass(java_mirror));
 447   }
 448 }
 449 
 450 oop HeapShared::scratch_java_mirror(BasicType t) {
 451   assert((uint)t < T_VOID+1, "range check");
 452   assert(!is_reference_type(t), "sanity");
 453   return _scratch_basic_type_mirrors[t].resolve();
 454 }
 455 
 456 oop HeapShared::scratch_java_mirror(Klass* k) {
 457   return _scratch_objects_table->get_oop(k);
 458 }
 459 
 460 void HeapShared::set_scratch_java_mirror(Klass* k, oop mirror) {
 461   _scratch_objects_table->set_oop(k, mirror);
 462 }
 463 
 464 void HeapShared::remove_scratch_objects(Klass* k) {
 465   // Klass is being deallocated. Java mirror can still be alive, and it should not
 466   // point to dead klass. We need to break the link from mirror to the Klass.
 467   // See how InstanceKlass::deallocate_contents does it for normal mirrors.
 468   oop mirror = _scratch_objects_table->get_oop(k);
 469   if (mirror != nullptr) {
 470     java_lang_Class::set_klass(mirror, nullptr);
 471   }
 472   _scratch_objects_table->remove_oop(k);
 473   if (k->is_instance_klass()) {
 474     _scratch_objects_table->remove(InstanceKlass::cast(k)->constants());
 475   }
 476 }
 477 
 478 //TODO: we eventually want a more direct test for these kinds of things.
 479 //For example the JVM could record some bit of context from the creation
 480 //of the klass, such as who called the hidden class factory.  Using
 481 //string compares on names is fragile and will break as soon as somebody
 482 //changes the names in the JDK code.  See discussion in JDK-8342481 for
 483 //related ideas about marking AOT-related classes.
 484 bool HeapShared::is_lambda_form_klass(InstanceKlass* ik) {
 485   return ik->is_hidden() &&
 486     (ik->name()->starts_with("java/lang/invoke/LambdaForm$MH+") ||
 487      ik->name()->starts_with("java/lang/invoke/LambdaForm$DMH+") ||
 488      ik->name()->starts_with("java/lang/invoke/LambdaForm$BMH+") ||
 489      ik->name()->starts_with("java/lang/invoke/LambdaForm$VH+"));
 490 }
 491 
 492 bool HeapShared::is_lambda_proxy_klass(InstanceKlass* ik) {
 493   return ik->is_hidden() && (ik->name()->index_of_at(0, "$$Lambda+", 9) > 0);
 494 }
 495 
 496 bool HeapShared::is_string_concat_klass(InstanceKlass* ik) {
 497   return ik->is_hidden() && ik->name()->starts_with("java/lang/String$$StringConcat");
 498 }
 499 
 500 bool HeapShared::is_archivable_hidden_klass(InstanceKlass* ik) {
 501   return CDSConfig::is_dumping_method_handles() &&
 502     (is_lambda_form_klass(ik) || is_lambda_proxy_klass(ik) || is_string_concat_klass(ik));
 503 }
 504 
 505 
 506 void HeapShared::copy_and_rescan_aot_inited_mirror(InstanceKlass* ik) {
 507   ik->set_has_aot_initialized_mirror();
 508   if (AOTClassInitializer::is_runtime_setup_required(ik)) {
 509     ik->set_is_runtime_setup_required();
 510   }
 511 
 512   oop orig_mirror;
 513   if (RegeneratedClasses::is_regenerated_object(ik)) {
 514     InstanceKlass* orig_ik = RegeneratedClasses::get_original_object(ik);
 515     precond(orig_ik->is_initialized());
 516     orig_mirror = orig_ik->java_mirror();
 517   } else {
 518     precond(ik->is_initialized());
 519     orig_mirror = ik->java_mirror();
 520   }
 521 
 522   oop m = scratch_java_mirror(ik);
 523   int nfields = 0;
 524   for (JavaFieldStream fs(ik); !fs.done(); fs.next()) {
 525     if (fs.access_flags().is_static()) {
 526       fieldDescriptor& fd = fs.field_descriptor();
 527       int offset = fd.offset();
 528       switch (fd.field_type()) {
 529       case T_OBJECT:
 530       case T_ARRAY:
 531         {
 532           oop field_obj = orig_mirror->obj_field(offset);
 533           if (offset == java_lang_Class::reflection_data_offset()) {
 534             // Class::reflectData use SoftReference, which cannot be archived. Set it
 535             // to null and it will be recreated at runtime.
 536             field_obj = nullptr;
 537           }
 538           m->obj_field_put(offset, field_obj);
 539           if (field_obj != nullptr) {
 540             bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, field_obj);
 541             assert(success, "sanity");
 542           }
 543         }
 544         break;
 545       case T_BOOLEAN:
 546         m->bool_field_put(offset, orig_mirror->bool_field(offset));
 547         break;
 548       case T_BYTE:
 549         m->byte_field_put(offset, orig_mirror->byte_field(offset));
 550         break;
 551       case T_SHORT:
 552         m->short_field_put(offset, orig_mirror->short_field(offset));
 553         break;
 554       case T_CHAR:
 555         m->char_field_put(offset, orig_mirror->char_field(offset));
 556         break;
 557       case T_INT:
 558         m->int_field_put(offset, orig_mirror->int_field(offset));
 559         break;
 560       case T_LONG:
 561         m->long_field_put(offset, orig_mirror->long_field(offset));
 562         break;
 563       case T_FLOAT:
 564         m->float_field_put(offset, orig_mirror->float_field(offset));
 565         break;
 566       case T_DOUBLE:
 567         m->double_field_put(offset, orig_mirror->double_field(offset));
 568         break;
 569       default:
 570         ShouldNotReachHere();
 571       }
 572       nfields ++;
 573     }
 574   }
 575 
 576   oop class_data = java_lang_Class::class_data(orig_mirror);
 577   java_lang_Class::set_class_data(m, class_data);
 578   if (class_data != nullptr) {
 579     bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, class_data);
 580     assert(success, "sanity");
 581   }
 582 
 583   if (log_is_enabled(Debug, aot, init)) {
 584     ResourceMark rm;
 585     log_debug(aot, init)("copied %3d field(s) in aot-initialized mirror %s%s%s", nfields, ik->external_name(),
 586                          ik->is_hidden() ? " (hidden)" : "",
 587                          ik->is_enum_subclass() ? " (enum)" : "");
 588   }
 589 }
 590 
 591 static void copy_java_mirror_hashcode(oop orig_mirror, oop scratch_m) {
 592   // We need to retain the identity_hash, because it may have been used by some hashtables
 593   // in the shared heap.
 594   if (!orig_mirror->fast_no_hash_check()) {
 595     intptr_t src_hash = orig_mirror->identity_hash();
 596     if (UseCompactObjectHeaders) {
 597       narrowKlass nk = CompressedKlassPointers::encode(orig_mirror->klass());
 598       scratch_m->set_mark(markWord::prototype().set_narrow_klass(nk).copy_set_hash(src_hash));
 599     } else {
 600       scratch_m->set_mark(markWord::prototype().copy_set_hash(src_hash));
 601     }
 602     assert(scratch_m->mark().is_unlocked(), "sanity");
 603 
 604     DEBUG_ONLY(intptr_t archived_hash = scratch_m->identity_hash());
 605     assert(src_hash == archived_hash, "Different hash codes: original " INTPTR_FORMAT ", archived " INTPTR_FORMAT, src_hash, archived_hash);
 606   }
 607 }
 608 
 609 static objArrayOop get_archived_resolved_references(InstanceKlass* src_ik) {
 610   if (SystemDictionaryShared::is_builtin_loader(src_ik->class_loader_data())) {
 611     objArrayOop rr = src_ik->constants()->resolved_references_or_null();
 612     if (rr != nullptr && !ArchiveHeapWriter::is_too_large_to_archive(rr)) {
 613       return HeapShared::scratch_resolved_references(src_ik->constants());
 614     }
 615   }
 616   return nullptr;
 617 }
 618 
 619 void HeapShared::archive_strings() {
 620   oop shared_strings_array = StringTable::init_shared_strings_array();
 621   bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, shared_strings_array);
 622   assert(success, "shared strings array must not point to arrays or strings that are too large to archive");
 623   StringTable::set_shared_strings_array_index(append_root(shared_strings_array));
 624 }
 625 
 626 int HeapShared::archive_exception_instance(oop exception) {
 627   bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, exception);
 628   assert(success, "sanity");
 629   return append_root(exception);
 630 }
 631 
 632 void HeapShared::mark_native_pointers(oop orig_obj) {
 633   if (java_lang_Class::is_instance(orig_obj)) {
 634     ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::klass_offset());
 635     ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::array_klass_offset());
 636   } else if (java_lang_invoke_ResolvedMethodName::is_instance(orig_obj)) {
 637     ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_invoke_ResolvedMethodName::vmtarget_offset());
 638   }
 639 }
 640 
 641 void HeapShared::get_pointer_info(oop src_obj, bool& has_oop_pointers, bool& has_native_pointers) {
 642   CachedOopInfo* info = archived_object_cache()->get(src_obj);
 643   assert(info != nullptr, "must be");
 644   has_oop_pointers = info->has_oop_pointers();
 645   has_native_pointers = info->has_native_pointers();
 646 }
 647 
 648 void HeapShared::set_has_native_pointers(oop src_obj) {
 649   CachedOopInfo* info = archived_object_cache()->get(src_obj);
 650   assert(info != nullptr, "must be");
 651   info->set_has_native_pointers();
 652 }
 653 
 654 // Between start_scanning_for_oops() and end_scanning_for_oops(), we discover all Java heap objects that
 655 // should be stored in the AOT cache. The scanning is coordinated by AOTArtifactFinder.
 656 void HeapShared::start_scanning_for_oops() {
 657   {
 658     NoSafepointVerifier nsv;
 659 
 660     // The special subgraph doesn't belong to any class. We use Object_klass() here just
 661     // for convenience.
 662     _dump_time_special_subgraph = init_subgraph_info(vmClasses::Object_klass(), false);
 663 
 664     // Cache for recording where the archived objects are copied to
 665     create_archived_object_cache();
 666 
 667     if (UseCompressedOops || UseG1GC) {
 668       aot_log_info(aot)("Heap range = [" PTR_FORMAT " - "  PTR_FORMAT "]",
 669                     UseCompressedOops ? p2i(CompressedOops::begin()) :
 670                                         p2i((address)G1CollectedHeap::heap()->reserved().start()),
 671                     UseCompressedOops ? p2i(CompressedOops::end()) :
 672                                         p2i((address)G1CollectedHeap::heap()->reserved().end()));
 673     }
 674 
 675     archive_subgraphs();
 676   }
 677 
 678   init_seen_objects_table();
 679   Universe::archive_exception_instances();
 680 }
 681 
 682 void HeapShared::end_scanning_for_oops() {
 683   archive_strings();
 684   delete_seen_objects_table();
 685 }
 686 
 687 void HeapShared::write_heap(ArchiveHeapInfo *heap_info) {
 688   {
 689     NoSafepointVerifier nsv;
 690     CDSHeapVerifier::verify();
 691     check_special_subgraph_classes();
 692   }
 693 
 694   StringTable::write_shared_table();
 695   ArchiveHeapWriter::write(_pending_roots, heap_info);
 696 
 697   ArchiveBuilder::OtherROAllocMark mark;
 698   write_subgraph_info_table();
 699 }
 700 
 701 void HeapShared::scan_java_mirror(oop orig_mirror) {
 702   oop m = scratch_java_mirror(orig_mirror);
 703   if (m != nullptr) { // nullptr if for custom class loader
 704     copy_java_mirror_hashcode(orig_mirror, m);
 705     bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, m);
 706     assert(success, "sanity");
 707   }
 708 }
 709 
 710 void HeapShared::scan_java_class(Klass* orig_k) {
 711   scan_java_mirror(orig_k->java_mirror());
 712 
 713   if (orig_k->is_instance_klass()) {
 714     InstanceKlass* orig_ik = InstanceKlass::cast(orig_k);
 715     orig_ik->constants()->prepare_resolved_references_for_archiving();
 716     objArrayOop rr = get_archived_resolved_references(orig_ik);
 717     if (rr != nullptr) {
 718       bool success = HeapShared::archive_reachable_objects_from(1, _dump_time_special_subgraph, rr);
 719       assert(success, "must be");
 720     }
 721   }
 722 }
 723 
 724 void HeapShared::archive_subgraphs() {
 725   assert(CDSConfig::is_dumping_heap(), "must be");
 726 
 727   archive_object_subgraphs(archive_subgraph_entry_fields,
 728                            false /* is_full_module_graph */);
 729 
 730   if (CDSConfig::is_dumping_full_module_graph()) {
 731     archive_object_subgraphs(fmg_archive_subgraph_entry_fields,
 732                              true /* is_full_module_graph */);
 733     Modules::verify_archived_modules();
 734   }
 735 }
 736 
 737 //
 738 // Subgraph archiving support
 739 //
 740 HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = nullptr;
 741 HeapShared::RunTimeKlassSubGraphInfoTable   HeapShared::_run_time_subgraph_info_table;
 742 
 743 // Get the subgraph_info for Klass k. A new subgraph_info is created if
 744 // there is no existing one for k. The subgraph_info records the "buffered"
 745 // address of the class.
 746 KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
 747   assert(CDSConfig::is_dumping_heap(), "dump time only");
 748   bool created;
 749   KlassSubGraphInfo* info =
 750     _dump_time_subgraph_info_table->put_if_absent(k, KlassSubGraphInfo(k, is_full_module_graph),
 751                                                   &created);
 752   assert(created, "must not initialize twice");
 753   return info;
 754 }
 755 
 756 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
 757   assert(CDSConfig::is_dumping_heap(), "dump time only");
 758   KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
 759   assert(info != nullptr, "must have been initialized");
 760   return info;
 761 }
 762 
 763 // Add an entry field to the current KlassSubGraphInfo.
 764 void KlassSubGraphInfo::add_subgraph_entry_field(int static_field_offset, oop v) {
 765   assert(CDSConfig::is_dumping_heap(), "dump time only");
 766   if (_subgraph_entry_fields == nullptr) {
 767     _subgraph_entry_fields =
 768       new (mtClass) GrowableArray<int>(10, mtClass);
 769   }
 770   _subgraph_entry_fields->append(static_field_offset);
 771   _subgraph_entry_fields->append(HeapShared::append_root(v));
 772 }
 773 
 774 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
 775 // Only objects of boot classes can be included in sub-graph.
 776 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
 777   assert(CDSConfig::is_dumping_heap(), "dump time only");
 778 
 779   if (_subgraph_object_klasses == nullptr) {
 780     _subgraph_object_klasses =
 781       new (mtClass) GrowableArray<Klass*>(50, mtClass);
 782   }
 783 
 784   if (_k == orig_k) {
 785     // Don't add the Klass containing the sub-graph to it's own klass
 786     // initialization list.
 787     return;
 788   }
 789 
 790   if (orig_k->is_instance_klass()) {
 791 #ifdef ASSERT
 792     InstanceKlass* ik = InstanceKlass::cast(orig_k);
 793     if (CDSConfig::is_dumping_method_handles()) {
 794       // -XX:AOTInitTestClass must be used carefully in regression tests to
 795       // include only classes that are safe to aot-initialize.
 796       assert(ik->class_loader() == nullptr ||
 797              HeapShared::is_lambda_proxy_klass(ik) ||
 798              AOTClassInitializer::has_test_class(),
 799             "we can archive only instances of boot classes or lambda proxy classes");
 800     } else {
 801       assert(ik->class_loader() == nullptr, "must be boot class");
 802     }
 803 #endif
 804     // vmClasses::xxx_klass() are not updated, need to check
 805     // the original Klass*
 806     if (orig_k == vmClasses::String_klass() ||
 807         orig_k == vmClasses::Object_klass()) {
 808       // Initialized early during VM initialization. No need to be added
 809       // to the sub-graph object class list.
 810       return;
 811     }
 812     check_allowed_klass(InstanceKlass::cast(orig_k));
 813   } else if (orig_k->is_objArray_klass()) {
 814     Klass* abk = ObjArrayKlass::cast(orig_k)->bottom_klass();
 815     if (abk->is_instance_klass()) {
 816       assert(InstanceKlass::cast(abk)->defined_by_boot_loader(),
 817             "must be boot class");
 818       check_allowed_klass(InstanceKlass::cast(ObjArrayKlass::cast(orig_k)->bottom_klass()));
 819     }
 820     if (orig_k == Universe::objectArrayKlass()) {
 821       // Initialized early during Universe::genesis. No need to be added
 822       // to the list.
 823       return;
 824     }
 825   } else {
 826     assert(orig_k->is_typeArray_klass(), "must be");
 827     // Primitive type arrays are created early during Universe::genesis.
 828     return;
 829   }
 830 
 831   if (log_is_enabled(Debug, aot, heap)) {
 832     if (!_subgraph_object_klasses->contains(orig_k)) {
 833       ResourceMark rm;
 834       log_debug(aot, heap)("Adding klass %s", orig_k->external_name());
 835     }
 836   }
 837 
 838   _subgraph_object_klasses->append_if_missing(orig_k);
 839   _has_non_early_klasses |= is_non_early_klass(orig_k);
 840 }
 841 
 842 void KlassSubGraphInfo::check_allowed_klass(InstanceKlass* ik) {
 843 #ifndef PRODUCT
 844   if (AOTClassInitializer::has_test_class()) {
 845     // The tests can cache arbitrary types of objects.
 846     return;
 847   }
 848 #endif
 849 
 850   if (ik->module()->name() == vmSymbols::java_base()) {
 851     assert(ik->package() != nullptr, "classes in java.base cannot be in unnamed package");
 852     return;
 853   }
 854 
 855   const char* lambda_msg = "";
 856   if (CDSConfig::is_dumping_method_handles()) {
 857     lambda_msg = ", or a lambda proxy class";
 858     if (HeapShared::is_lambda_proxy_klass(ik) &&
 859         (ik->class_loader() == nullptr ||
 860          ik->class_loader() == SystemDictionary::java_platform_loader() ||
 861          ik->class_loader() == SystemDictionary::java_system_loader())) {
 862       return;
 863     }
 864   }
 865 
 866 #ifndef PRODUCT
 867   if (!ik->module()->is_named() && ik->package() == nullptr && ArchiveHeapTestClass != nullptr) {
 868     // This class is loaded by ArchiveHeapTestClass
 869     return;
 870   }
 871   const char* testcls_msg = ", or a test class in an unnamed package of an unnamed module";
 872 #else
 873   const char* testcls_msg = "";
 874 #endif
 875 
 876   ResourceMark rm;
 877   log_error(aot, heap)("Class %s not allowed in archive heap. Must be in java.base%s%s",
 878                        ik->external_name(), lambda_msg, testcls_msg);
 879   MetaspaceShared::unrecoverable_writing_error();
 880 }
 881 
 882 bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
 883   if (k->is_objArray_klass()) {
 884     k = ObjArrayKlass::cast(k)->bottom_klass();
 885   }
 886   if (k->is_instance_klass()) {
 887     if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
 888       ResourceMark rm;
 889       log_info(aot, heap)("non-early: %s", k->external_name());
 890       return true;
 891     } else {
 892       return false;
 893     }
 894   } else {
 895     return false;
 896   }
 897 }
 898 
 899 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
 900 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
 901   _k = ArchiveBuilder::get_buffered_klass(info->klass());
 902   _entry_field_records = nullptr;
 903   _subgraph_object_klasses = nullptr;
 904   _is_full_module_graph = info->is_full_module_graph();
 905 
 906   if (_is_full_module_graph) {
 907     // Consider all classes referenced by the full module graph as early -- we will be
 908     // allocating objects of these classes during JVMTI early phase, so they cannot
 909     // be processed by (non-early) JVMTI ClassFileLoadHook
 910     _has_non_early_klasses = false;
 911   } else {
 912     _has_non_early_klasses = info->has_non_early_klasses();
 913   }
 914 
 915   if (_has_non_early_klasses) {
 916     ResourceMark rm;
 917     log_info(aot, heap)(
 918           "Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
 919           _k->external_name());
 920   }
 921 
 922   // populate the entry fields
 923   GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
 924   if (entry_fields != nullptr) {
 925     int num_entry_fields = entry_fields->length();
 926     assert(num_entry_fields % 2 == 0, "sanity");
 927     _entry_field_records =
 928       ArchiveBuilder::new_ro_array<int>(num_entry_fields);
 929     for (int i = 0 ; i < num_entry_fields; i++) {
 930       _entry_field_records->at_put(i, entry_fields->at(i));
 931     }
 932   }
 933 
 934   // <recorded_klasses> has the Klasses of all the objects that are referenced by this subgraph.
 935   // Copy those that need to be explicitly initialized into <_subgraph_object_klasses>.
 936   GrowableArray<Klass*>* recorded_klasses = info->subgraph_object_klasses();
 937   if (recorded_klasses != nullptr) {
 938     // AOT-inited classes are automatically marked as "initialized" during bootstrap. When
 939     // programmatically loading a subgraph, we only need to explicitly initialize the classes
 940     // that are not aot-inited.
 941     int num_to_copy = 0;
 942     for (int i = 0; i < recorded_klasses->length(); i++) {
 943       Klass* subgraph_k = ArchiveBuilder::get_buffered_klass(recorded_klasses->at(i));
 944       if (!subgraph_k->has_aot_initialized_mirror()) {
 945         num_to_copy ++;
 946       }
 947     }
 948 
 949     _subgraph_object_klasses = ArchiveBuilder::new_ro_array<Klass*>(num_to_copy);
 950     bool is_special = (_k == ArchiveBuilder::get_buffered_klass(vmClasses::Object_klass()));
 951     for (int i = 0, n = 0; i < recorded_klasses->length(); i++) {
 952       Klass* subgraph_k = ArchiveBuilder::get_buffered_klass(recorded_klasses->at(i));
 953       if (subgraph_k->has_aot_initialized_mirror()) {
 954         continue;
 955       }
 956       if (log_is_enabled(Info, aot, heap)) {
 957         ResourceMark rm;
 958         const char* owner_name =  is_special ? "<special>" : _k->external_name();
 959         if (subgraph_k->is_instance_klass()) {
 960           InstanceKlass* src_ik = InstanceKlass::cast(ArchiveBuilder::current()->get_source_addr(subgraph_k));
 961         }
 962         log_info(aot, heap)(
 963           "Archived object klass %s (%2d) => %s",
 964           owner_name, n, subgraph_k->external_name());
 965       }
 966       _subgraph_object_klasses->at_put(n, subgraph_k);
 967       ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(n));
 968       n++;
 969     }
 970   }
 971 
 972   ArchivePtrMarker::mark_pointer(&_k);
 973   ArchivePtrMarker::mark_pointer(&_entry_field_records);
 974   ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
 975 }
 976 
 977 class HeapShared::CopyKlassSubGraphInfoToArchive : StackObj {
 978   CompactHashtableWriter* _writer;
 979 public:
 980   CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
 981 
 982   bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
 983     if (info.subgraph_object_klasses() != nullptr || info.subgraph_entry_fields() != nullptr) {
 984       ArchivedKlassSubGraphInfoRecord* record = HeapShared::archive_subgraph_info(&info);
 985       Klass* buffered_k = ArchiveBuilder::get_buffered_klass(klass);
 986       unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary((address)buffered_k);
 987       u4 delta = ArchiveBuilder::current()->any_to_offset_u4(record);
 988       _writer->add(hash, delta);
 989     }
 990     return true; // keep on iterating
 991   }
 992 };
 993 
 994 ArchivedKlassSubGraphInfoRecord* HeapShared::archive_subgraph_info(KlassSubGraphInfo* info) {
 995   ArchivedKlassSubGraphInfoRecord* record =
 996       (ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
 997   record->init(info);
 998   if (info ==  _dump_time_special_subgraph) {
 999     _run_time_special_subgraph = record;
1000   }
1001   return record;
1002 }
1003 
1004 // Build the records of archived subgraph infos, which include:
1005 // - Entry points to all subgraphs from the containing class mirror. The entry
1006 //   points are static fields in the mirror. For each entry point, the field
1007 //   offset, and value are recorded in the sub-graph
1008 //   info. The value is stored back to the corresponding field at runtime.
1009 // - A list of klasses that need to be loaded/initialized before archived
1010 //   java object sub-graph can be accessed at runtime.
1011 void HeapShared::write_subgraph_info_table() {
1012   // Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
1013   DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
1014   CompactHashtableStats stats;
1015 
1016   _run_time_subgraph_info_table.reset();
1017 
1018   CompactHashtableWriter writer(d_table->_count, &stats);
1019   CopyKlassSubGraphInfoToArchive copy(&writer);
1020   d_table->iterate(&copy);
1021   writer.dump(&_run_time_subgraph_info_table, "subgraphs");
1022 
1023 #ifndef PRODUCT
1024   if (ArchiveHeapTestClass != nullptr) {
1025     size_t len = strlen(ArchiveHeapTestClass) + 1;
1026     Array<char>* array = ArchiveBuilder::new_ro_array<char>((int)len);
1027     strncpy(array->adr_at(0), ArchiveHeapTestClass, len);
1028     _archived_ArchiveHeapTestClass = array;
1029   }
1030 #endif
1031   if (log_is_enabled(Info, aot, heap)) {
1032     print_stats();
1033   }
1034 }
1035 
1036 void HeapShared::add_root_segment(objArrayOop segment_oop) {
1037   assert(segment_oop != nullptr, "must be");
1038   assert(ArchiveHeapLoader::is_in_use(), "must be");
1039   if (_root_segments == nullptr) {
1040     _root_segments = new GrowableArrayCHeap<OopHandle, mtClassShared>(10);
1041   }
1042   _root_segments->push(OopHandle(Universe::vm_global(), segment_oop));
1043 }
1044 
1045 void HeapShared::init_root_segment_sizes(int max_size_elems) {
1046   _root_segment_max_size_elems = max_size_elems;
1047 }
1048 
1049 void HeapShared::serialize_tables(SerializeClosure* soc) {
1050 
1051 #ifndef PRODUCT
1052   soc->do_ptr(&_archived_ArchiveHeapTestClass);
1053   if (soc->reading() && _archived_ArchiveHeapTestClass != nullptr) {
1054     _test_class_name = _archived_ArchiveHeapTestClass->adr_at(0);
1055     setup_test_class(_test_class_name);
1056   }
1057 #endif
1058 
1059   _run_time_subgraph_info_table.serialize_header(soc);
1060   soc->do_ptr(&_run_time_special_subgraph);
1061 }
1062 
1063 static void verify_the_heap(Klass* k, const char* which) {
1064   if (VerifyArchivedFields > 0) {
1065     ResourceMark rm;
1066     log_info(aot, heap)("Verify heap %s initializing static field(s) in %s",
1067                         which, k->external_name());
1068 
1069     VM_Verify verify_op;
1070     VMThread::execute(&verify_op);
1071 
1072     if (VerifyArchivedFields > 1 && is_init_completed()) {
1073       // At this time, the oop->klass() of some archived objects in the heap may not
1074       // have been loaded into the system dictionary yet. Nevertheless, oop->klass() should
1075       // have enough information (object size, oop maps, etc) so that a GC can be safely
1076       // performed.
1077       //
1078       // -XX:VerifyArchivedFields=2 force a GC to happen in such an early stage
1079       // to check for GC safety.
1080       log_info(aot, heap)("Trigger GC %s initializing static field(s) in %s",
1081                           which, k->external_name());
1082       FlagSetting fs1(VerifyBeforeGC, true);
1083       FlagSetting fs2(VerifyDuringGC, true);
1084       FlagSetting fs3(VerifyAfterGC,  true);
1085       Universe::heap()->collect(GCCause::_java_lang_system_gc);
1086     }
1087   }
1088 }
1089 
1090 // Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
1091 // have a valid klass. I.e., oopDesc::klass() must have already been resolved.
1092 //
1093 // Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
1094 // ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
1095 // this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
1096 void HeapShared::resolve_classes(JavaThread* current) {
1097   assert(CDSConfig::is_using_archive(), "runtime only!");
1098   if (!ArchiveHeapLoader::is_in_use()) {
1099     return; // nothing to do
1100   }
1101   resolve_classes_for_subgraphs(current, archive_subgraph_entry_fields);
1102   resolve_classes_for_subgraphs(current, fmg_archive_subgraph_entry_fields);
1103 }
1104 
1105 void HeapShared::resolve_classes_for_subgraphs(JavaThread* current, ArchivableStaticFieldInfo fields[]) {
1106   for (int i = 0; fields[i].valid(); i++) {
1107     ArchivableStaticFieldInfo* info = &fields[i];
1108     TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
1109     InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
1110     assert(k != nullptr && k->defined_by_boot_loader(), "sanity");
1111     resolve_classes_for_subgraph_of(current, k);
1112   }
1113 }
1114 
1115 void HeapShared::resolve_classes_for_subgraph_of(JavaThread* current, Klass* k) {
1116   JavaThread* THREAD = current;
1117   ExceptionMark em(THREAD);
1118   const ArchivedKlassSubGraphInfoRecord* record =
1119    resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
1120   if (HAS_PENDING_EXCEPTION) {
1121    CLEAR_PENDING_EXCEPTION;
1122   }
1123   if (record == nullptr) {
1124    clear_archived_roots_of(k);
1125   }
1126 }
1127 
1128 void HeapShared::initialize_java_lang_invoke(TRAPS) {
1129   if (CDSConfig::is_using_aot_linked_classes() || CDSConfig::is_dumping_method_handles()) {
1130     resolve_or_init("java/lang/invoke/Invokers$Holder", true, CHECK);
1131     resolve_or_init("java/lang/invoke/MethodHandle", true, CHECK);
1132     resolve_or_init("java/lang/invoke/MethodHandleNatives", true, CHECK);
1133     resolve_or_init("java/lang/invoke/DirectMethodHandle$Holder", true, CHECK);
1134     resolve_or_init("java/lang/invoke/DelegatingMethodHandle$Holder", true, CHECK);
1135     resolve_or_init("java/lang/invoke/LambdaForm$Holder", true, CHECK);
1136     resolve_or_init("java/lang/invoke/BoundMethodHandle$Species_L", true, CHECK);
1137   }
1138 }
1139 
1140 // Initialize the InstanceKlasses of objects that are reachable from the following roots:
1141 //   - interned strings
1142 //   - Klass::java_mirror() -- including aot-initialized mirrors such as those of Enum klasses.
1143 //   - ConstantPool::resolved_references()
1144 //   - Universe::<xxx>_exception_instance()
1145 //
1146 // For example, if this enum class is initialized at AOT cache assembly time:
1147 //
1148 //    enum Fruit {
1149 //       APPLE, ORANGE, BANANA;
1150 //       static final Set<Fruit> HAVE_SEEDS = new HashSet<>(Arrays.asList(APPLE, ORANGE));
1151 //   }
1152 //
1153 // the aot-initialized mirror of Fruit has a static field that references HashSet, which
1154 // should be initialized before any Java code can access the Fruit class. Note that
1155 // HashSet itself doesn't necessary need to be an aot-initialized class.
1156 void HeapShared::init_classes_for_special_subgraph(Handle class_loader, TRAPS) {
1157   if (!ArchiveHeapLoader::is_in_use()) {
1158     return;
1159   }
1160 
1161   assert( _run_time_special_subgraph != nullptr, "must be");
1162   Array<Klass*>* klasses = _run_time_special_subgraph->subgraph_object_klasses();
1163   if (klasses != nullptr) {
1164     for (int pass = 0; pass < 2; pass ++) {
1165       for (int i = 0; i < klasses->length(); i++) {
1166         Klass* k = klasses->at(i);
1167         if (k->class_loader_data() == nullptr) {
1168           // This class is not yet loaded. We will initialize it in a later phase.
1169           // For example, we have loaded only AOTLinkedClassCategory::BOOT1 classes
1170           // but k is part of AOTLinkedClassCategory::BOOT2.
1171           continue;
1172         }
1173         if (k->class_loader() == class_loader()) {
1174           if (pass == 0) {
1175             if (k->is_instance_klass()) {
1176               InstanceKlass::cast(k)->link_class(CHECK);
1177             }
1178           } else {
1179             resolve_or_init(k, /*do_init*/true, CHECK);
1180           }
1181         }
1182       }
1183     }
1184   }
1185 }
1186 
1187 void HeapShared::initialize_from_archived_subgraph(JavaThread* current, Klass* k) {
1188   JavaThread* THREAD = current;
1189   if (!ArchiveHeapLoader::is_in_use()) {
1190     return; // nothing to do
1191   }
1192 
1193   if (k->name()->equals("jdk/internal/module/ArchivedModuleGraph") &&
1194       !CDSConfig::is_using_optimized_module_handling() &&
1195       // archive was created with --module-path
1196       AOTClassLocationConfig::runtime()->num_module_paths() > 0) {
1197     // ArchivedModuleGraph was created with a --module-path that's different than the runtime --module-path.
1198     // Thus, it might contain references to modules that do not exist at runtime. We cannot use it.
1199     log_info(aot, heap)("Skip initializing ArchivedModuleGraph subgraph: is_using_optimized_module_handling=%s num_module_paths=%d",
1200                         BOOL_TO_STR(CDSConfig::is_using_optimized_module_handling()),
1201                         AOTClassLocationConfig::runtime()->num_module_paths());
1202     return;
1203   }
1204 
1205   ExceptionMark em(THREAD);
1206   const ArchivedKlassSubGraphInfoRecord* record =
1207     resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
1208 
1209   if (HAS_PENDING_EXCEPTION) {
1210     CLEAR_PENDING_EXCEPTION;
1211     // None of the field value will be set if there was an exception when initializing the classes.
1212     // The java code will not see any of the archived objects in the
1213     // subgraphs referenced from k in this case.
1214     return;
1215   }
1216 
1217   if (record != nullptr) {
1218     init_archived_fields_for(k, record);
1219   }
1220 }
1221 
1222 const ArchivedKlassSubGraphInfoRecord*
1223 HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
1224   assert(!CDSConfig::is_dumping_heap(), "Should not be called when dumping heap");
1225 
1226   if (!k->is_shared()) {
1227     return nullptr;
1228   }
1229   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
1230   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
1231 
1232 #ifndef PRODUCT
1233   if (_test_class_name != nullptr && k->name()->equals(_test_class_name) && record != nullptr) {
1234     _test_class = k;
1235     _test_class_record = record;
1236   }
1237 #endif
1238 
1239   // Initialize from archived data. Currently this is done only
1240   // during VM initialization time. No lock is needed.
1241   if (record == nullptr) {
1242     if (log_is_enabled(Info, aot, heap)) {
1243       ResourceMark rm(THREAD);
1244       log_info(aot, heap)("subgraph %s is not recorded",
1245                           k->external_name());
1246     }
1247     return nullptr;
1248   } else {
1249     if (record->is_full_module_graph() && !CDSConfig::is_using_full_module_graph()) {
1250       if (log_is_enabled(Info, aot, heap)) {
1251         ResourceMark rm(THREAD);
1252         log_info(aot, heap)("subgraph %s cannot be used because full module graph is disabled",
1253                             k->external_name());
1254       }
1255       return nullptr;
1256     }
1257 
1258     if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
1259       if (log_is_enabled(Info, aot, heap)) {
1260         ResourceMark rm(THREAD);
1261         log_info(aot, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
1262                             k->external_name());
1263       }
1264       return nullptr;
1265     }
1266 
1267     if (log_is_enabled(Info, aot, heap)) {
1268       ResourceMark rm;
1269       log_info(aot, heap)("%s subgraph %s ", do_init ? "init" : "resolve", k->external_name());
1270     }
1271 
1272     resolve_or_init(k, do_init, CHECK_NULL);
1273 
1274     // Load/link/initialize the klasses of the objects in the subgraph.
1275     // nullptr class loader is used.
1276     Array<Klass*>* klasses = record->subgraph_object_klasses();
1277     if (klasses != nullptr) {
1278       for (int i = 0; i < klasses->length(); i++) {
1279         Klass* klass = klasses->at(i);
1280         if (!klass->is_shared()) {
1281           return nullptr;
1282         }
1283         resolve_or_init(klass, do_init, CHECK_NULL);
1284       }
1285     }
1286   }
1287 
1288   return record;
1289 }
1290 
1291 void HeapShared::resolve_or_init(const char* klass_name, bool do_init, TRAPS) {
1292   TempNewSymbol klass_name_sym =  SymbolTable::new_symbol(klass_name);
1293   InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name_sym);
1294   if (k == nullptr) {
1295     return;
1296   }
1297   assert(k->defined_by_boot_loader(), "sanity");
1298   resolve_or_init(k, false, CHECK);
1299   if (do_init) {
1300     resolve_or_init(k, true, CHECK);
1301   }
1302 }
1303 
1304 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
1305   if (!do_init) {
1306     if (k->class_loader_data() == nullptr) {
1307       Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
1308       assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
1309     }
1310   } else {
1311     assert(k->class_loader_data() != nullptr, "must have been resolved by HeapShared::resolve_classes");
1312     if (k->is_instance_klass()) {
1313       InstanceKlass* ik = InstanceKlass::cast(k);
1314       ik->initialize(CHECK);
1315     } else if (k->is_objArray_klass()) {
1316       ObjArrayKlass* oak = ObjArrayKlass::cast(k);
1317       oak->initialize(CHECK);
1318     }
1319   }
1320 }
1321 
1322 void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record) {
1323   verify_the_heap(k, "before");
1324 
1325   // Load the subgraph entry fields from the record and store them back to
1326   // the corresponding fields within the mirror.
1327   oop m = k->java_mirror();
1328   Array<int>* entry_field_records = record->entry_field_records();
1329   if (entry_field_records != nullptr) {
1330     int efr_len = entry_field_records->length();
1331     assert(efr_len % 2 == 0, "sanity");
1332     for (int i = 0; i < efr_len; i += 2) {
1333       int field_offset = entry_field_records->at(i);
1334       int root_index = entry_field_records->at(i+1);
1335       oop v = get_root(root_index, /*clear=*/true);
1336       if (k->has_aot_initialized_mirror()) {
1337         assert(v == m->obj_field(field_offset), "must be aot-initialized");
1338       } else {
1339         m->obj_field_put(field_offset, v);
1340       }
1341       log_debug(aot, heap)("  " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
1342     }
1343 
1344     // Done. Java code can see the archived sub-graphs referenced from k's
1345     // mirror after this point.
1346     if (log_is_enabled(Info, aot, heap)) {
1347       ResourceMark rm;
1348       log_info(aot, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s%s",
1349                           k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "",
1350                           k->has_aot_initialized_mirror() ? " (aot-inited)" : "");
1351     }
1352   }
1353 
1354   verify_the_heap(k, "after ");
1355 }
1356 
1357 void HeapShared::clear_archived_roots_of(Klass* k) {
1358   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
1359   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
1360   if (record != nullptr) {
1361     Array<int>* entry_field_records = record->entry_field_records();
1362     if (entry_field_records != nullptr) {
1363       int efr_len = entry_field_records->length();
1364       assert(efr_len % 2 == 0, "sanity");
1365       for (int i = 0; i < efr_len; i += 2) {
1366         int root_index = entry_field_records->at(i+1);
1367         clear_root(root_index);
1368       }
1369     }
1370   }
1371 }
1372 
1373 // Push all oop fields (or oop array elemenets in case of an objArray) in
1374 // _referencing_obj onto the _stack.
1375 class HeapShared::OopFieldPusher: public BasicOopIterateClosure {
1376   PendingOopStack* _stack;
1377   GrowableArray<oop> _found_oop_fields;
1378   int _level;
1379   bool _record_klasses_only;
1380   KlassSubGraphInfo* _subgraph_info;
1381   oop _referencing_obj;
1382   bool _is_java_lang_ref;
1383  public:
1384   OopFieldPusher(PendingOopStack* stack,
1385                  int level,
1386                  bool record_klasses_only,
1387                  KlassSubGraphInfo* subgraph_info,
1388                  oop orig) :
1389     _stack(stack),
1390     _found_oop_fields(),
1391     _level(level),
1392     _record_klasses_only(record_klasses_only),
1393     _subgraph_info(subgraph_info),
1394     _referencing_obj(orig) {
1395     _is_java_lang_ref = AOTReferenceObjSupport::check_if_ref_obj(orig);
1396   }
1397   void do_oop(narrowOop *p) { OopFieldPusher::do_oop_work(p); }
1398   void do_oop(      oop *p) { OopFieldPusher::do_oop_work(p); }
1399 
1400   ~OopFieldPusher() {
1401     while (_found_oop_fields.length() > 0) {
1402       // This produces the exact same traversal order as the previous version
1403       // of OopFieldPusher that recurses on the C stack -- a depth-first search,
1404       // walking the oop fields in _referencing_obj by ascending field offsets.
1405       oop obj = _found_oop_fields.pop();
1406       _stack->push(PendingOop(obj, _referencing_obj, _level + 1));
1407     }
1408   }
1409 
1410  protected:
1411   template <class T> void do_oop_work(T *p) {
1412     int field_offset = pointer_delta_as_int((char*)p, cast_from_oop<char*>(_referencing_obj));
1413     oop obj = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_load_at(_referencing_obj, field_offset);
1414     if (!CompressedOops::is_null(obj)) {
1415       if (_is_java_lang_ref && AOTReferenceObjSupport::skip_field(field_offset)) {
1416         // Do not follow these fields. They will be cleared to null.
1417         return;
1418       }
1419 
1420       if (!_record_klasses_only && log_is_enabled(Debug, aot, heap)) {
1421         ResourceMark rm;
1422         log_debug(aot, heap)("(%d) %s[%d] ==> " PTR_FORMAT " size %zu %s", _level,
1423                              _referencing_obj->klass()->external_name(), field_offset,
1424                              p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
1425         if (log_is_enabled(Trace, aot, heap)) {
1426           LogTarget(Trace, aot, heap) log;
1427           LogStream out(log);
1428           obj->print_on(&out);
1429         }
1430       }
1431 
1432       _found_oop_fields.push(obj);
1433     }
1434   }
1435 
1436  public:
1437   oop referencing_obj()                       { return _referencing_obj;      }
1438   KlassSubGraphInfo* subgraph_info()          { return _subgraph_info;        }
1439 };
1440 
1441 // Checks if an oop has any non-null oop fields
1442 class PointsToOopsChecker : public BasicOopIterateClosure {
1443   bool _result;
1444 
1445   template <class T> void check(T *p) {
1446     _result |= (HeapAccess<>::oop_load(p) != nullptr);
1447   }
1448 
1449 public:
1450   PointsToOopsChecker() : _result(false) {}
1451   void do_oop(narrowOop *p) { check(p); }
1452   void do_oop(      oop *p) { check(p); }
1453   bool result() { return _result; }
1454 };
1455 
1456 HeapShared::CachedOopInfo HeapShared::make_cached_oop_info(oop obj, oop referrer) {
1457   PointsToOopsChecker points_to_oops_checker;
1458   obj->oop_iterate(&points_to_oops_checker);
1459   return CachedOopInfo(referrer, points_to_oops_checker.result());
1460 }
1461 
1462 void HeapShared::init_box_classes(TRAPS) {
1463   if (ArchiveHeapLoader::is_in_use()) {
1464     vmClasses::Boolean_klass()->initialize(CHECK);
1465     vmClasses::Character_klass()->initialize(CHECK);
1466     vmClasses::Float_klass()->initialize(CHECK);
1467     vmClasses::Double_klass()->initialize(CHECK);
1468     vmClasses::Byte_klass()->initialize(CHECK);
1469     vmClasses::Short_klass()->initialize(CHECK);
1470     vmClasses::Integer_klass()->initialize(CHECK);
1471     vmClasses::Long_klass()->initialize(CHECK);
1472     vmClasses::Void_klass()->initialize(CHECK);
1473   }
1474 }
1475 
1476 // (1) If orig_obj has not been archived yet, archive it.
1477 // (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
1478 //     trace all  objects that are reachable from it, and make sure these objects are archived.
1479 // (3) Record the klasses of all objects that are reachable from orig_obj (including those that
1480 //     were already archived when this function is called)
1481 bool HeapShared::archive_reachable_objects_from(int level,
1482                                                 KlassSubGraphInfo* subgraph_info,
1483                                                 oop orig_obj) {
1484   assert(orig_obj != nullptr, "must be");
1485   PendingOopStack stack;
1486   stack.push(PendingOop(orig_obj, nullptr, level));
1487 
1488   while (stack.length() > 0) {
1489     PendingOop po = stack.pop();
1490     _object_being_archived = po;
1491     bool status = walk_one_object(&stack, po.level(), subgraph_info, po.obj(), po.referrer());
1492     _object_being_archived = PendingOop();
1493 
1494     if (!status) {
1495       // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1496       // as the Java code will take care of initializing this field dynamically.
1497       assert(level == 1, "VM should have exited with unarchivable objects for _level > 1");
1498       return false;
1499     }
1500   }
1501 
1502   return true;
1503 }
1504 
1505 bool HeapShared::walk_one_object(PendingOopStack* stack, int level, KlassSubGraphInfo* subgraph_info,
1506                                  oop orig_obj, oop referrer) {
1507   assert(orig_obj != nullptr, "must be");
1508   if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
1509     // This object has injected fields that cannot be supported easily, so we disallow them for now.
1510     // If you get an error here, you probably made a change in the JDK library that has added
1511     // these objects that are referenced (directly or indirectly) by static fields.
1512     ResourceMark rm;
1513     log_error(aot, heap)("Cannot archive object " PTR_FORMAT " of class %s", p2i(orig_obj), orig_obj->klass()->external_name());
1514     debug_trace();
1515     MetaspaceShared::unrecoverable_writing_error();
1516   }
1517 
1518   if (log_is_enabled(Debug, aot, heap) && java_lang_Class::is_instance(orig_obj)) {
1519     ResourceMark rm;
1520     LogTarget(Debug, aot, heap) log;
1521     LogStream out(log);
1522     out.print("Found java mirror " PTR_FORMAT " ", p2i(orig_obj));
1523     Klass* k = java_lang_Class::as_Klass(orig_obj);
1524     if (k != nullptr) {
1525       out.print("%s", k->external_name());
1526     } else {
1527       out.print("primitive");
1528     }
1529     out.print_cr("; scratch mirror = "  PTR_FORMAT,
1530                  p2i(scratch_java_mirror(orig_obj)));
1531   }
1532 
1533   if (java_lang_Class::is_instance(orig_obj)) {
1534     Klass* k = java_lang_Class::as_Klass(orig_obj);
1535     if (RegeneratedClasses::has_been_regenerated(k)) {
1536       orig_obj = RegeneratedClasses::get_regenerated_object(k)->java_mirror();
1537     }
1538   }
1539 
1540   if (CDSConfig::is_initing_classes_at_dump_time()) {
1541     if (java_lang_Class::is_instance(orig_obj)) {
1542       orig_obj = scratch_java_mirror(orig_obj);
1543       assert(orig_obj != nullptr, "must be archived");
1544     }
1545   } else if (java_lang_Class::is_instance(orig_obj) && subgraph_info != _dump_time_special_subgraph) {
1546     // Without CDSConfig::is_initing_classes_at_dump_time(), we only allow archived objects to
1547     // point to the mirrors of (1) j.l.Object, (2) primitive classes, and (3) box classes. These are initialized
1548     // very early by HeapShared::init_box_classes().
1549     if (orig_obj == vmClasses::Object_klass()->java_mirror()
1550         || java_lang_Class::is_primitive(orig_obj)
1551         || orig_obj == vmClasses::Boolean_klass()->java_mirror()
1552         || orig_obj == vmClasses::Character_klass()->java_mirror()
1553         || orig_obj == vmClasses::Float_klass()->java_mirror()
1554         || orig_obj == vmClasses::Double_klass()->java_mirror()
1555         || orig_obj == vmClasses::Byte_klass()->java_mirror()
1556         || orig_obj == vmClasses::Short_klass()->java_mirror()
1557         || orig_obj == vmClasses::Integer_klass()->java_mirror()
1558         || orig_obj == vmClasses::Long_klass()->java_mirror()
1559         || orig_obj == vmClasses::Void_klass()->java_mirror()) {
1560       orig_obj = scratch_java_mirror(orig_obj);
1561       assert(orig_obj != nullptr, "must be archived");
1562     } else {
1563       // If you get an error here, you probably made a change in the JDK library that has added a Class
1564       // object that is referenced (directly or indirectly) by an ArchivableStaticFieldInfo
1565       // defined at the top of this file.
1566       log_error(aot, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
1567       debug_trace();
1568       MetaspaceShared::unrecoverable_writing_error();
1569     }
1570   }
1571 
1572   if (has_been_seen_during_subgraph_recording(orig_obj)) {
1573     // orig_obj has already been archived and traced. Nothing more to do.
1574     return true;
1575   } else {
1576     set_has_been_seen_during_subgraph_recording(orig_obj);
1577   }
1578 
1579   bool already_archived = has_been_archived(orig_obj);
1580   bool record_klasses_only = already_archived;
1581   if (!already_archived) {
1582     ++_num_new_archived_objs;
1583     if (!archive_object(orig_obj, referrer, subgraph_info)) {
1584       // Skip archiving the sub-graph referenced from the current entry field.
1585       ResourceMark rm;
1586       log_error(aot, heap)(
1587         "Cannot archive the sub-graph referenced from %s object ("
1588         PTR_FORMAT ") size %zu, skipped.",
1589         orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
1590       if (level == 1) {
1591         // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1592         // as the Java code will take care of initializing this field dynamically.
1593         return false;
1594       } else {
1595         // We don't know how to handle an object that has been archived, but some of its reachable
1596         // objects cannot be archived. Bail out for now. We might need to fix this in the future if
1597         // we have a real use case.
1598         MetaspaceShared::unrecoverable_writing_error();
1599       }
1600     }
1601   }
1602 
1603   Klass *orig_k = orig_obj->klass();
1604   subgraph_info->add_subgraph_object_klass(orig_k);
1605 
1606   {
1607     // Find all the oops that are referenced by orig_obj, push them onto the stack
1608     // so we can work on them next.
1609     ResourceMark rm;
1610     OopFieldPusher pusher(stack, level, record_klasses_only, subgraph_info, orig_obj);
1611     orig_obj->oop_iterate(&pusher);
1612   }
1613 
1614   if (CDSConfig::is_initing_classes_at_dump_time()) {
1615     // The enum klasses are archived with aot-initialized mirror.
1616     // See AOTClassInitializer::can_archive_initialized_mirror().
1617   } else {
1618     if (CDSEnumKlass::is_enum_obj(orig_obj)) {
1619       CDSEnumKlass::handle_enum_obj(level + 1, subgraph_info, orig_obj);
1620     }
1621   }
1622 
1623   return true;
1624 }
1625 
1626 //
1627 // Start from the given static field in a java mirror and archive the
1628 // complete sub-graph of java heap objects that are reached directly
1629 // or indirectly from the starting object by following references.
1630 // Sub-graph archiving restrictions (current):
1631 //
1632 // - All classes of objects in the archived sub-graph (including the
1633 //   entry class) must be boot class only.
1634 // - No java.lang.Class instance (java mirror) can be included inside
1635 //   an archived sub-graph. Mirror can only be the sub-graph entry object.
1636 //
1637 // The Java heap object sub-graph archiving process (see OopFieldPusher):
1638 //
1639 // 1) Java object sub-graph archiving starts from a given static field
1640 // within a Class instance (java mirror). If the static field is a
1641 // reference field and points to a non-null java object, proceed to
1642 // the next step.
1643 //
1644 // 2) Archives the referenced java object. If an archived copy of the
1645 // current object already exists, updates the pointer in the archived
1646 // copy of the referencing object to point to the current archived object.
1647 // Otherwise, proceed to the next step.
1648 //
1649 // 3) Follows all references within the current java object and recursively
1650 // archive the sub-graph of objects starting from each reference.
1651 //
1652 // 4) Updates the pointer in the archived copy of referencing object to
1653 // point to the current archived object.
1654 //
1655 // 5) The Klass of the current java object is added to the list of Klasses
1656 // for loading and initializing before any object in the archived graph can
1657 // be accessed at runtime.
1658 //
1659 void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
1660                                                              const char* klass_name,
1661                                                              int field_offset,
1662                                                              const char* field_name) {
1663   assert(CDSConfig::is_dumping_heap(), "dump time only");
1664   assert(k->defined_by_boot_loader(), "must be boot class");
1665 
1666   oop m = k->java_mirror();
1667 
1668   KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
1669   oop f = m->obj_field(field_offset);
1670 
1671   log_debug(aot, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
1672 
1673   if (!CompressedOops::is_null(f)) {
1674     if (log_is_enabled(Trace, aot, heap)) {
1675       LogTarget(Trace, aot, heap) log;
1676       LogStream out(log);
1677       f->print_on(&out);
1678     }
1679 
1680     bool success = archive_reachable_objects_from(1, subgraph_info, f);
1681     if (!success) {
1682       log_error(aot, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
1683                            klass_name, field_name);
1684     } else {
1685       // Note: the field value is not preserved in the archived mirror.
1686       // Record the field as a new subGraph entry point. The recorded
1687       // information is restored from the archive at runtime.
1688       subgraph_info->add_subgraph_entry_field(field_offset, f);
1689       log_info(aot, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(f));
1690     }
1691   } else {
1692     // The field contains null, we still need to record the entry point,
1693     // so it can be restored at runtime.
1694     subgraph_info->add_subgraph_entry_field(field_offset, nullptr);
1695   }
1696 }
1697 
1698 #ifndef PRODUCT
1699 class VerifySharedOopClosure: public BasicOopIterateClosure {
1700  public:
1701   void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
1702   void do_oop(      oop *p) { VerifySharedOopClosure::do_oop_work(p); }
1703 
1704  protected:
1705   template <class T> void do_oop_work(T *p) {
1706     oop obj = RawAccess<>::oop_load(p);
1707     if (!CompressedOops::is_null(obj)) {
1708       HeapShared::verify_reachable_objects_from(obj);
1709     }
1710   }
1711 };
1712 
1713 void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
1714   assert(CDSConfig::is_dumping_heap(), "dump time only");
1715   assert(k->defined_by_boot_loader(), "must be boot class");
1716 
1717   oop m = k->java_mirror();
1718   oop f = m->obj_field(field_offset);
1719   if (!CompressedOops::is_null(f)) {
1720     verify_subgraph_from(f);
1721   }
1722 }
1723 
1724 void HeapShared::verify_subgraph_from(oop orig_obj) {
1725   if (!has_been_archived(orig_obj)) {
1726     // It's OK for the root of a subgraph to be not archived. See comments in
1727     // archive_reachable_objects_from().
1728     return;
1729   }
1730 
1731   // Verify that all objects reachable from orig_obj are archived.
1732   init_seen_objects_table();
1733   verify_reachable_objects_from(orig_obj);
1734   delete_seen_objects_table();
1735 }
1736 
1737 void HeapShared::verify_reachable_objects_from(oop obj) {
1738   _num_total_verifications ++;
1739   if (java_lang_Class::is_instance(obj)) {
1740     obj = scratch_java_mirror(obj);
1741     assert(obj != nullptr, "must be");
1742   }
1743   if (!has_been_seen_during_subgraph_recording(obj)) {
1744     set_has_been_seen_during_subgraph_recording(obj);
1745     assert(has_been_archived(obj), "must be");
1746     VerifySharedOopClosure walker;
1747     obj->oop_iterate(&walker);
1748   }
1749 }
1750 #endif
1751 
1752 void HeapShared::check_special_subgraph_classes() {
1753   if (CDSConfig::is_initing_classes_at_dump_time()) {
1754     // We can have aot-initialized classes (such as Enums) that can reference objects
1755     // of arbitrary types. Currently, we trust the JEP 483 implementation to only
1756     // aot-initialize classes that are "safe".
1757     //
1758     // TODO: we need an automatic tool that checks the safety of aot-initialized
1759     // classes (when we extend the set of aot-initialized classes beyond JEP 483)
1760     return;
1761   } else {
1762     // In this case, the special subgraph should contain a few specific types
1763     GrowableArray<Klass*>* klasses = _dump_time_special_subgraph->subgraph_object_klasses();
1764     int num = klasses->length();
1765     for (int i = 0; i < num; i++) {
1766       Klass* subgraph_k = klasses->at(i);
1767       Symbol* name = subgraph_k->name();
1768       if (subgraph_k->is_instance_klass() &&
1769           name != vmSymbols::java_lang_Class() &&
1770           name != vmSymbols::java_lang_String() &&
1771           name != vmSymbols::java_lang_ArithmeticException() &&
1772           name != vmSymbols::java_lang_ArrayIndexOutOfBoundsException() &&
1773           name != vmSymbols::java_lang_ArrayStoreException() &&
1774           name != vmSymbols::java_lang_ClassCastException() &&
1775           name != vmSymbols::java_lang_InternalError() &&
1776           name != vmSymbols::java_lang_NullPointerException()) {
1777         ResourceMark rm;
1778         fatal("special subgraph cannot have objects of type %s", subgraph_k->external_name());
1779       }
1780     }
1781   }
1782 }
1783 
1784 HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = nullptr;
1785 HeapShared::PendingOop HeapShared::_object_being_archived;
1786 int HeapShared::_num_new_walked_objs;
1787 int HeapShared::_num_new_archived_objs;
1788 int HeapShared::_num_old_recorded_klasses;
1789 
1790 int HeapShared::_num_total_subgraph_recordings = 0;
1791 int HeapShared::_num_total_walked_objs = 0;
1792 int HeapShared::_num_total_archived_objs = 0;
1793 int HeapShared::_num_total_recorded_klasses = 0;
1794 int HeapShared::_num_total_verifications = 0;
1795 
1796 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
1797   return _seen_objects_table->get(obj) != nullptr;
1798 }
1799 
1800 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
1801   assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
1802   _seen_objects_table->put_when_absent(obj, true);
1803   _seen_objects_table->maybe_grow();
1804   ++ _num_new_walked_objs;
1805 }
1806 
1807 void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
1808   log_info(aot, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
1809   init_subgraph_info(k, is_full_module_graph);
1810   init_seen_objects_table();
1811   _num_new_walked_objs = 0;
1812   _num_new_archived_objs = 0;
1813   _num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
1814 }
1815 
1816 void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
1817   int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
1818     _num_old_recorded_klasses;
1819   log_info(aot, heap)("Done recording subgraph(s) for archived fields in %s: "
1820                       "walked %d objs, archived %d new objs, recorded %d classes",
1821                       class_name, _num_new_walked_objs, _num_new_archived_objs,
1822                       num_new_recorded_klasses);
1823 
1824   delete_seen_objects_table();
1825 
1826   _num_total_subgraph_recordings ++;
1827   _num_total_walked_objs      += _num_new_walked_objs;
1828   _num_total_archived_objs    += _num_new_archived_objs;
1829   _num_total_recorded_klasses +=  num_new_recorded_klasses;
1830 }
1831 
1832 class ArchivableStaticFieldFinder: public FieldClosure {
1833   InstanceKlass* _ik;
1834   Symbol* _field_name;
1835   bool _found;
1836   int _offset;
1837 public:
1838   ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
1839     _ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
1840 
1841   virtual void do_field(fieldDescriptor* fd) {
1842     if (fd->name() == _field_name) {
1843       assert(!_found, "fields can never be overloaded");
1844       if (is_reference_type(fd->field_type())) {
1845         _found = true;
1846         _offset = fd->offset();
1847       }
1848     }
1849   }
1850   bool found()     { return _found;  }
1851   int offset()     { return _offset; }
1852 };
1853 
1854 void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
1855                                             TRAPS) {
1856   for (int i = 0; fields[i].valid(); i++) {
1857     ArchivableStaticFieldInfo* info = &fields[i];
1858     TempNewSymbol klass_name =  SymbolTable::new_symbol(info->klass_name);
1859     TempNewSymbol field_name =  SymbolTable::new_symbol(info->field_name);
1860     ResourceMark rm; // for stringStream::as_string() etc.
1861 
1862 #ifndef PRODUCT
1863     bool is_test_class = (ArchiveHeapTestClass != nullptr) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
1864     const char* test_class_name = ArchiveHeapTestClass;
1865 #else
1866     bool is_test_class = false;
1867     const char* test_class_name = ""; // avoid C++ printf checks warnings.
1868 #endif
1869 
1870     if (is_test_class) {
1871       log_warning(aot)("Loading ArchiveHeapTestClass %s ...", test_class_name);
1872     }
1873 
1874     Klass* k = SystemDictionary::resolve_or_fail(klass_name, true, THREAD);
1875     if (HAS_PENDING_EXCEPTION) {
1876       CLEAR_PENDING_EXCEPTION;
1877       stringStream st;
1878       st.print("Fail to initialize archive heap: %s cannot be loaded by the boot loader", info->klass_name);
1879       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1880     }
1881 
1882     if (!k->is_instance_klass()) {
1883       stringStream st;
1884       st.print("Fail to initialize archive heap: %s is not an instance class", info->klass_name);
1885       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1886     }
1887 
1888     InstanceKlass* ik = InstanceKlass::cast(k);
1889     assert(InstanceKlass::cast(ik)->defined_by_boot_loader(),
1890            "Only support boot classes");
1891 
1892     if (is_test_class) {
1893       if (ik->module()->is_named()) {
1894         // We don't want ArchiveHeapTestClass to be abused to easily load/initialize arbitrary
1895         // core-lib classes. You need to at least append to the bootclasspath.
1896         stringStream st;
1897         st.print("ArchiveHeapTestClass %s is not in unnamed module", test_class_name);
1898         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1899       }
1900 
1901       if (ik->package() != nullptr) {
1902         // This restriction makes HeapShared::is_a_test_class_in_unnamed_module() easy.
1903         stringStream st;
1904         st.print("ArchiveHeapTestClass %s is not in unnamed package", test_class_name);
1905         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1906       }
1907     } else {
1908       if (ik->module()->name() != vmSymbols::java_base()) {
1909         // We don't want to deal with cases when a module is unavailable at runtime.
1910         // FUTURE -- load from archived heap only when module graph has not changed
1911         //           between dump and runtime.
1912         stringStream st;
1913         st.print("%s is not in java.base module", info->klass_name);
1914         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1915       }
1916     }
1917 
1918     if (is_test_class) {
1919       log_warning(aot)("Initializing ArchiveHeapTestClass %s ...", test_class_name);
1920     }
1921     ik->initialize(CHECK);
1922 
1923     ArchivableStaticFieldFinder finder(ik, field_name);
1924     ik->do_local_static_fields(&finder);
1925     if (!finder.found()) {
1926       stringStream st;
1927       st.print("Unable to find the static T_OBJECT field %s::%s", info->klass_name, info->field_name);
1928       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1929     }
1930 
1931     info->klass = ik;
1932     info->offset = finder.offset();
1933   }
1934 }
1935 
1936 void HeapShared::init_subgraph_entry_fields(TRAPS) {
1937   assert(CDSConfig::is_dumping_heap(), "must be");
1938   _dump_time_subgraph_info_table = new (mtClass)DumpTimeKlassSubGraphInfoTable();
1939   init_subgraph_entry_fields(archive_subgraph_entry_fields, CHECK);
1940   if (CDSConfig::is_dumping_full_module_graph()) {
1941     init_subgraph_entry_fields(fmg_archive_subgraph_entry_fields, CHECK);
1942   }
1943 }
1944 
1945 #ifndef PRODUCT
1946 void HeapShared::setup_test_class(const char* test_class_name) {
1947   ArchivableStaticFieldInfo* p = archive_subgraph_entry_fields;
1948   int num_slots = sizeof(archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
1949   assert(p[num_slots - 2].klass_name == nullptr, "must have empty slot that's patched below");
1950   assert(p[num_slots - 1].klass_name == nullptr, "must have empty slot that marks the end of the list");
1951 
1952   if (test_class_name != nullptr) {
1953     p[num_slots - 2].klass_name = test_class_name;
1954     p[num_slots - 2].field_name = ARCHIVE_TEST_FIELD_NAME;
1955   }
1956 }
1957 
1958 // See if ik is one of the test classes that are pulled in by -XX:ArchiveHeapTestClass
1959 // during runtime. This may be called before the module system is initialized so
1960 // we cannot rely on InstanceKlass::module(), etc.
1961 bool HeapShared::is_a_test_class_in_unnamed_module(Klass* ik) {
1962   if (_test_class != nullptr) {
1963     if (ik == _test_class) {
1964       return true;
1965     }
1966     Array<Klass*>* klasses = _test_class_record->subgraph_object_klasses();
1967     if (klasses == nullptr) {
1968       return false;
1969     }
1970 
1971     for (int i = 0; i < klasses->length(); i++) {
1972       Klass* k = klasses->at(i);
1973       if (k == ik) {
1974         Symbol* name;
1975         if (k->is_instance_klass()) {
1976           name = InstanceKlass::cast(k)->name();
1977         } else if (k->is_objArray_klass()) {
1978           Klass* bk = ObjArrayKlass::cast(k)->bottom_klass();
1979           if (!bk->is_instance_klass()) {
1980             return false;
1981           }
1982           name = bk->name();
1983         } else {
1984           return false;
1985         }
1986 
1987         // See KlassSubGraphInfo::check_allowed_klass() - we only allow test classes
1988         // to be:
1989         //   (A) java.base classes (which must not be in the unnamed module)
1990         //   (B) test classes which must be in the unnamed package of the unnamed module.
1991         // So if we see a '/' character in the class name, it must be in (A);
1992         // otherwise it must be in (B).
1993         if (name->index_of_at(0, "/", 1)  >= 0) {
1994           return false; // (A)
1995         }
1996 
1997         return true; // (B)
1998       }
1999     }
2000   }
2001 
2002   return false;
2003 }
2004 
2005 void HeapShared::initialize_test_class_from_archive(JavaThread* current) {
2006   Klass* k = _test_class;
2007   if (k != nullptr && ArchiveHeapLoader::is_in_use()) {
2008     JavaThread* THREAD = current;
2009     ExceptionMark em(THREAD);
2010     const ArchivedKlassSubGraphInfoRecord* record =
2011       resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
2012 
2013     // The _test_class is in the unnamed module, so it can't call CDS.initializeFromArchive()
2014     // from its <clinit> method. So we set up its "archivedObjects" field first, before
2015     // calling its <clinit>. This is not strictly clean, but it's a convenient way to write unit
2016     // test cases (see test/hotspot/jtreg/runtime/cds/appcds/cacheObject/ArchiveHeapTestClass.java).
2017     if (record != nullptr) {
2018       init_archived_fields_for(k, record);
2019     }
2020     resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
2021   }
2022 }
2023 #endif
2024 
2025 void HeapShared::init_for_dumping(TRAPS) {
2026   if (CDSConfig::is_dumping_heap()) {
2027     setup_test_class(ArchiveHeapTestClass);
2028     _dumped_interned_strings = new (mtClass)DumpedInternedStrings(INITIAL_TABLE_SIZE, MAX_TABLE_SIZE);
2029     init_subgraph_entry_fields(CHECK);
2030   }
2031 }
2032 
2033 void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
2034                                           bool is_full_module_graph) {
2035   _num_total_subgraph_recordings = 0;
2036   _num_total_walked_objs = 0;
2037   _num_total_archived_objs = 0;
2038   _num_total_recorded_klasses = 0;
2039   _num_total_verifications = 0;
2040 
2041   // For each class X that has one or more archived fields:
2042   // [1] Dump the subgraph of each archived field
2043   // [2] Create a list of all the class of the objects that can be reached
2044   //     by any of these static fields.
2045   //     At runtime, these classes are initialized before X's archived fields
2046   //     are restored by HeapShared::initialize_from_archived_subgraph().
2047   for (int i = 0; fields[i].valid(); ) {
2048     ArchivableStaticFieldInfo* info = &fields[i];
2049     const char* klass_name = info->klass_name;
2050     start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
2051 
2052     // If you have specified consecutive fields of the same klass in
2053     // fields[], these will be archived in the same
2054     // {start_recording_subgraph ... done_recording_subgraph} pass to
2055     // save time.
2056     for (; fields[i].valid(); i++) {
2057       ArchivableStaticFieldInfo* f = &fields[i];
2058       if (f->klass_name != klass_name) {
2059         break;
2060       }
2061 
2062       archive_reachable_objects_from_static_field(f->klass, f->klass_name,
2063                                                   f->offset, f->field_name);
2064     }
2065     done_recording_subgraph(info->klass, klass_name);
2066   }
2067 
2068   log_info(aot, heap)("Archived subgraph records = %d",
2069                       _num_total_subgraph_recordings);
2070   log_info(aot, heap)("  Walked %d objects", _num_total_walked_objs);
2071   log_info(aot, heap)("  Archived %d objects", _num_total_archived_objs);
2072   log_info(aot, heap)("  Recorded %d klasses", _num_total_recorded_klasses);
2073 
2074 #ifndef PRODUCT
2075   for (int i = 0; fields[i].valid(); i++) {
2076     ArchivableStaticFieldInfo* f = &fields[i];
2077     verify_subgraph_from_static_field(f->klass, f->offset);
2078   }
2079   log_info(aot, heap)("  Verified %d references", _num_total_verifications);
2080 #endif
2081 }
2082 
2083 // Keep track of the contents of the archived interned string table. This table
2084 // is used only by CDSHeapVerifier.
2085 void HeapShared::add_to_dumped_interned_strings(oop string) {
2086   assert_at_safepoint(); // DumpedInternedStrings uses raw oops
2087   assert(!ArchiveHeapWriter::is_string_too_large_to_archive(string), "must be");
2088   bool created;
2089   _dumped_interned_strings->put_if_absent(string, true, &created);
2090   if (created) {
2091     // Prevent string deduplication from changing the value field to
2092     // something not in the archive.
2093     java_lang_String::set_deduplication_forbidden(string);
2094     _dumped_interned_strings->maybe_grow();
2095   }
2096 }
2097 
2098 bool HeapShared::is_dumped_interned_string(oop o) {
2099   return _dumped_interned_strings->get(o) != nullptr;
2100 }
2101 
2102 void HeapShared::debug_trace() {
2103   ResourceMark rm;
2104   oop referrer = _object_being_archived.referrer();
2105   if (referrer != nullptr) {
2106     LogStream ls(Log(aot, heap)::error());
2107     ls.print_cr("Reference trace");
2108     CDSHeapVerifier::trace_to_root(&ls, referrer);
2109   }
2110 }
2111 
2112 #ifndef PRODUCT
2113 // At dump-time, find the location of all the non-null oop pointers in an archived heap
2114 // region. This way we can quickly relocate all the pointers without using
2115 // BasicOopIterateClosure at runtime.
2116 class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
2117   void* _start;
2118   BitMap *_oopmap;
2119   int _num_total_oops;
2120   int _num_null_oops;
2121  public:
2122   FindEmbeddedNonNullPointers(void* start, BitMap* oopmap)
2123     : _start(start), _oopmap(oopmap), _num_total_oops(0),  _num_null_oops(0) {}
2124 
2125   virtual void do_oop(narrowOop* p) {
2126     assert(UseCompressedOops, "sanity");
2127     _num_total_oops ++;
2128     narrowOop v = *p;
2129     if (!CompressedOops::is_null(v)) {
2130       size_t idx = p - (narrowOop*)_start;
2131       _oopmap->set_bit(idx);
2132     } else {
2133       _num_null_oops ++;
2134     }
2135   }
2136   virtual void do_oop(oop* p) {
2137     assert(!UseCompressedOops, "sanity");
2138     _num_total_oops ++;
2139     if ((*p) != nullptr) {
2140       size_t idx = p - (oop*)_start;
2141       _oopmap->set_bit(idx);
2142     } else {
2143       _num_null_oops ++;
2144     }
2145   }
2146   int num_total_oops() const { return _num_total_oops; }
2147   int num_null_oops()  const { return _num_null_oops; }
2148 };
2149 #endif
2150 
2151 void HeapShared::count_allocation(size_t size) {
2152   _total_obj_count ++;
2153   _total_obj_size += size;
2154   for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
2155     if (size <= (size_t(1) << i)) {
2156       _alloc_count[i] ++;
2157       _alloc_size[i] += size;
2158       return;
2159     }
2160   }
2161 }
2162 
2163 static double avg_size(size_t size, size_t count) {
2164   double avg = 0;
2165   if (count > 0) {
2166     avg = double(size * HeapWordSize) / double(count);
2167   }
2168   return avg;
2169 }
2170 
2171 void HeapShared::print_stats() {
2172   size_t huge_count = _total_obj_count;
2173   size_t huge_size = _total_obj_size;
2174 
2175   for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
2176     size_t byte_size_limit = (size_t(1) << i) * HeapWordSize;
2177     size_t count = _alloc_count[i];
2178     size_t size = _alloc_size[i];
2179     log_info(aot, heap)("%8zu objects are <= %-6zu"
2180                         " bytes (total %8zu bytes, avg %8.1f bytes)",
2181                         count, byte_size_limit, size * HeapWordSize, avg_size(size, count));
2182     huge_count -= count;
2183     huge_size -= size;
2184   }
2185 
2186   log_info(aot, heap)("%8zu huge  objects               (total %8zu bytes"
2187                       ", avg %8.1f bytes)",
2188                       huge_count, huge_size * HeapWordSize,
2189                       avg_size(huge_size, huge_count));
2190   log_info(aot, heap)("%8zu total objects               (total %8zu bytes"
2191                       ", avg %8.1f bytes)",
2192                       _total_obj_count, _total_obj_size * HeapWordSize,
2193                       avg_size(_total_obj_size, _total_obj_count));
2194 }
2195 
2196 bool HeapShared::is_archived_boot_layer_available(JavaThread* current) {
2197   TempNewSymbol klass_name = SymbolTable::new_symbol(ARCHIVED_BOOT_LAYER_CLASS);
2198   InstanceKlass* k = SystemDictionary::find_instance_klass(current, klass_name, Handle());
2199   if (k == nullptr) {
2200     return false;
2201   } else {
2202     TempNewSymbol field_name = SymbolTable::new_symbol(ARCHIVED_BOOT_LAYER_FIELD);
2203     TempNewSymbol field_signature = SymbolTable::new_symbol("Ljdk/internal/module/ArchivedBootLayer;");
2204     fieldDescriptor fd;
2205     if (k->find_field(field_name, field_signature, true, &fd) != nullptr) {
2206       oop m = k->java_mirror();
2207       oop f = m->obj_field(fd.offset());
2208       if (CompressedOops::is_null(f)) {
2209         return false;
2210       }
2211     } else {
2212       return false;
2213     }
2214   }
2215   return true;
2216 }
2217 
2218 #endif // INCLUDE_CDS_JAVA_HEAP