1 /*
   2  * Copyright (c) 2018, 2023, 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 "precompiled.hpp"
  26 #include "cds/archiveBuilder.hpp"
  27 #include "cds/archiveHeapLoader.hpp"
  28 #include "cds/archiveHeapWriter.hpp"
  29 #include "cds/archiveUtils.hpp"
  30 #include "cds/cdsHeapVerifier.hpp"
  31 #include "cds/heapShared.hpp"
  32 #include "cds/metaspaceShared.hpp"
  33 #include "classfile/classLoaderData.hpp"
  34 #include "classfile/javaClasses.inline.hpp"
  35 #include "classfile/modules.hpp"
  36 #include "classfile/stringTable.hpp"
  37 #include "classfile/symbolTable.hpp"
  38 #include "classfile/systemDictionary.hpp"
  39 #include "classfile/systemDictionaryShared.hpp"
  40 #include "classfile/vmClasses.hpp"
  41 #include "classfile/vmSymbols.hpp"
  42 #include "gc/shared/collectedHeap.hpp"
  43 #include "gc/shared/gcLocker.hpp"
  44 #include "gc/shared/gcVMOperations.hpp"
  45 #include "logging/log.hpp"
  46 #include "logging/logStream.hpp"
  47 #include "memory/iterator.inline.hpp"
  48 #include "memory/resourceArea.hpp"
  49 #include "memory/universe.hpp"
  50 #include "oops/compressedOops.inline.hpp"
  51 #include "oops/fieldStreams.inline.hpp"
  52 #include "oops/objArrayOop.inline.hpp"
  53 #include "oops/oop.inline.hpp"
  54 #include "oops/typeArrayOop.inline.hpp"
  55 #include "prims/jvmtiExport.hpp"
  56 #include "runtime/fieldDescriptor.inline.hpp"
  57 #include "runtime/init.hpp"
  58 #include "runtime/javaCalls.hpp"
  59 #include "runtime/mutexLocker.hpp"
  60 #include "runtime/safepointVerifiers.hpp"
  61 #include "utilities/bitMap.inline.hpp"
  62 #include "utilities/copy.hpp"
  63 #if INCLUDE_G1GC
  64 #include "gc/g1/g1CollectedHeap.hpp"
  65 #endif
  66 
  67 #if INCLUDE_CDS_JAVA_HEAP
  68 
  69 struct ArchivableStaticFieldInfo {
  70   const char* klass_name;
  71   const char* field_name;
  72   InstanceKlass* klass;
  73   int offset;
  74   BasicType type;
  75 
  76   ArchivableStaticFieldInfo(const char* k, const char* f)
  77   : klass_name(k), field_name(f), klass(nullptr), offset(0), type(T_ILLEGAL) {}
  78 
  79   bool valid() {
  80     return klass_name != nullptr;
  81   }
  82 };
  83 
  84 bool HeapShared::_disable_writing = false;
  85 DumpedInternedStrings *HeapShared::_dumped_interned_strings = nullptr;
  86 
  87 size_t HeapShared::_alloc_count[HeapShared::ALLOC_STAT_SLOTS];
  88 size_t HeapShared::_alloc_size[HeapShared::ALLOC_STAT_SLOTS];
  89 size_t HeapShared::_total_obj_count;
  90 size_t HeapShared::_total_obj_size;
  91 
  92 #ifndef PRODUCT
  93 #define ARCHIVE_TEST_FIELD_NAME "archivedObjects"
  94 static Array<char>* _archived_ArchiveHeapTestClass = nullptr;
  95 static const char* _test_class_name = nullptr;
  96 static const Klass* _test_class = nullptr;
  97 static const ArchivedKlassSubGraphInfoRecord* _test_class_record = nullptr;
  98 #endif
  99 
 100 
 101 //
 102 // If you add new entries to the following tables, you should know what you're doing!
 103 //
 104 
 105 static ArchivableStaticFieldInfo archive_subgraph_entry_fields[] = {
 106   {"java/lang/Integer$IntegerCache",              "archivedCache"},
 107   {"java/lang/Long$LongCache",                    "archivedCache"},
 108   {"java/lang/Byte$ByteCache",                    "archivedCache"},
 109   {"java/lang/Short$ShortCache",                  "archivedCache"},
 110   {"java/lang/Character$CharacterCache",          "archivedCache"},
 111   {"java/util/jar/Attributes$Name",               "KNOWN_NAMES"},
 112   {"sun/util/locale/BaseLocale",                  "constantBaseLocales"},
 113   {"jdk/internal/module/ArchivedModuleGraph",     "archivedModuleGraph"},
 114   {"java/util/ImmutableCollections",              "archivedObjects"},
 115   {"java/lang/ModuleLayer",                       "EMPTY_LAYER"},
 116   {"java/lang/module/Configuration",              "EMPTY_CONFIGURATION"},
 117   {"jdk/internal/math/FDBigInteger",              "archivedCaches"},
 118 #ifndef PRODUCT
 119   {nullptr, nullptr}, // Extra slot for -XX:ArchiveHeapTestClass
 120 #endif
 121   {nullptr, nullptr},
 122 };
 123 
 124 // full module graph
 125 static ArchivableStaticFieldInfo fmg_archive_subgraph_entry_fields[] = {
 126   {"jdk/internal/loader/ArchivedClassLoaders",    "archivedClassLoaders"},
 127   {"jdk/internal/module/ArchivedBootLayer",       "archivedBootLayer"},
 128   {"java/lang/Module$ArchivedData",               "archivedData"},
 129   {nullptr, nullptr},
 130 };
 131 
 132 KlassSubGraphInfo* HeapShared::_default_subgraph_info;
 133 GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = nullptr;
 134 OopHandle HeapShared::_roots;
 135 OopHandle HeapShared::_scratch_basic_type_mirrors[T_VOID+1];
 136 KlassToOopHandleTable* HeapShared::_scratch_java_mirror_table = nullptr;
 137 
 138 static bool is_subgraph_root_class_of(ArchivableStaticFieldInfo fields[], InstanceKlass* ik) {
 139   for (int i = 0; fields[i].valid(); i++) {
 140     if (fields[i].klass == ik) {
 141       return true;
 142     }
 143   }
 144   return false;
 145 }
 146 
 147 bool HeapShared::is_subgraph_root_class(InstanceKlass* ik) {
 148   return is_subgraph_root_class_of(archive_subgraph_entry_fields, ik) ||
 149          is_subgraph_root_class_of(fmg_archive_subgraph_entry_fields, ik);
 150 }
 151 
 152 unsigned HeapShared::oop_hash(oop const& p) {
 153   // Do not call p->identity_hash() as that will update the
 154   // object header.
 155   return primitive_hash(cast_from_oop<intptr_t>(p));
 156 }
 157 
 158 static void reset_states(oop obj, TRAPS) {
 159   Handle h_obj(THREAD, obj);
 160   InstanceKlass* klass = InstanceKlass::cast(obj->klass());
 161   TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
 162   Symbol* method_sig = vmSymbols::void_method_signature();
 163 
 164   while (klass != nullptr) {
 165     Method* method = klass->find_method(method_name, method_sig);
 166     if (method != nullptr) {
 167       assert(method->is_private(), "must be");
 168       if (log_is_enabled(Debug, cds)) {
 169         ResourceMark rm(THREAD);
 170         log_debug(cds)("  calling %s", method->name_and_sig_as_C_string());
 171       }
 172       JavaValue result(T_VOID);
 173       JavaCalls::call_special(&result, h_obj, klass,
 174                               method_name, method_sig, CHECK);
 175     }
 176     klass = klass->java_super();
 177   }
 178 }
 179 
 180 void HeapShared::reset_archived_object_states(TRAPS) {
 181   assert(DumpSharedSpaces, "dump-time only");
 182   log_debug(cds)("Resetting platform loader");
 183   reset_states(SystemDictionary::java_platform_loader(), CHECK);
 184   log_debug(cds)("Resetting system loader");
 185   reset_states(SystemDictionary::java_system_loader(), CHECK);
 186 
 187   // Clean up jdk.internal.loader.ClassLoaders::bootLoader(), which is not
 188   // directly used for class loading, but rather is used by the core library
 189   // to keep track of resources, etc, loaded by the null class loader.
 190   //
 191   // Note, this object is non-null, and is not the same as
 192   // ClassLoaderData::the_null_class_loader_data()->class_loader(),
 193   // which is null.
 194   log_debug(cds)("Resetting boot loader");
 195   JavaValue result(T_OBJECT);
 196   JavaCalls::call_static(&result,
 197                          vmClasses::jdk_internal_loader_ClassLoaders_klass(),
 198                          vmSymbols::bootLoader_name(),
 199                          vmSymbols::void_BuiltinClassLoader_signature(),
 200                          CHECK);
 201   Handle boot_loader(THREAD, result.get_oop());
 202   reset_states(boot_loader(), CHECK);
 203 }
 204 
 205 HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = nullptr;
 206 
 207 bool HeapShared::has_been_archived(oop obj) {
 208   assert(DumpSharedSpaces, "dump-time only");
 209   return archived_object_cache()->get(obj) != nullptr;
 210 }
 211 
 212 int HeapShared::append_root(oop obj) {
 213   assert(DumpSharedSpaces, "dump-time only");
 214 
 215   // No GC should happen since we aren't scanning _pending_roots.
 216   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 217 
 218   if (_pending_roots == nullptr) {
 219     _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
 220   }
 221 
 222   return _pending_roots->append(obj);
 223 }
 224 
 225 objArrayOop HeapShared::roots() {
 226   if (DumpSharedSpaces) {
 227     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 228     if (!HeapShared::can_write()) {
 229       return nullptr;
 230     }
 231   } else {
 232     assert(UseSharedSpaces, "must be");
 233   }
 234 
 235   objArrayOop roots = (objArrayOop)_roots.resolve();
 236   assert(roots != nullptr, "should have been initialized");
 237   return roots;
 238 }
 239 
 240 // Returns an objArray that contains all the roots of the archived objects
 241 oop HeapShared::get_root(int index, bool clear) {
 242   assert(index >= 0, "sanity");
 243   assert(!DumpSharedSpaces && UseSharedSpaces, "runtime only");
 244   assert(!_roots.is_empty(), "must have loaded shared heap");
 245   oop result = roots()->obj_at(index);
 246   if (clear) {
 247     clear_root(index);
 248   }
 249   return result;
 250 }
 251 
 252 void HeapShared::clear_root(int index) {
 253   assert(index >= 0, "sanity");
 254   assert(UseSharedSpaces, "must be");
 255   if (ArchiveHeapLoader::is_in_use()) {
 256     if (log_is_enabled(Debug, cds, heap)) {
 257       oop old = roots()->obj_at(index);
 258       log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
 259     }
 260     roots()->obj_at_put(index, nullptr);
 261   }
 262 }
 263 
 264 bool HeapShared::archive_object(oop obj) {
 265   assert(DumpSharedSpaces, "dump-time only");
 266 
 267   assert(!obj->is_stackChunk(), "do not archive stack chunks");
 268   if (has_been_archived(obj)) {
 269     return true;
 270   }
 271 
 272   if (ArchiveHeapWriter::is_too_large_to_archive(obj->size())) {
 273     log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
 274                          p2i(obj), obj->size());
 275     return false;
 276   } else {
 277     count_allocation(obj->size());
 278     ArchiveHeapWriter::add_source_obj(obj);
 279 
 280     // The archived objects are discovered in a predictable order. Compute
 281     // their identity_hash() as soon as we see them. This ensures that the
 282     // the identity_hash in the object header will have a predictable value,
 283     // making the archive reproducible.
 284     obj->identity_hash();
 285     CachedOopInfo info = make_cached_oop_info();
 286     archived_object_cache()->put(obj, info);
 287     mark_native_pointers(obj);
 288 
 289     if (log_is_enabled(Debug, cds, heap)) {
 290       ResourceMark rm;
 291       log_debug(cds, heap)("Archived heap object " PTR_FORMAT " : %s",
 292                            p2i(obj), obj->klass()->external_name());
 293     }
 294 
 295     if (java_lang_Module::is_instance(obj)) {
 296       if (Modules::check_module_oop(obj)) {
 297         Modules::update_oops_in_archived_module(obj, append_root(obj));
 298       }
 299       java_lang_Module::set_module_entry(obj, nullptr);
 300     } else if (java_lang_ClassLoader::is_instance(obj)) {
 301       // class_data will be restored explicitly at run time.
 302       guarantee(obj == SystemDictionary::java_platform_loader() ||
 303                 obj == SystemDictionary::java_system_loader() ||
 304                 java_lang_ClassLoader::loader_data(obj) == nullptr, "must be");
 305       java_lang_ClassLoader::release_set_loader_data(obj, nullptr);
 306     }
 307 
 308     return true;
 309   }
 310 }
 311 
 312 class KlassToOopHandleTable: public ResourceHashtable<Klass*, OopHandle,
 313     36137, // prime number
 314     AnyObj::C_HEAP,
 315     mtClassShared> {
 316 public:
 317   oop get_oop(Klass* k) {
 318     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 319     OopHandle* handle = get(k);
 320     if (handle != nullptr) {
 321       return handle->resolve();
 322     } else {
 323       return nullptr;
 324     }
 325   }
 326   void set_oop(Klass* k, oop o) {
 327     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 328     OopHandle handle(Universe::vm_global(), o);
 329     bool is_new = put(k, handle);
 330     assert(is_new, "cannot set twice");
 331   }
 332   void remove_oop(Klass* k) {
 333     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 334     OopHandle* handle = get(k);
 335     if (handle != nullptr) {
 336       handle->release(Universe::vm_global());
 337       remove(k);
 338     }
 339   }
 340 };
 341 
 342 void HeapShared::init_scratch_objects(TRAPS) {
 343   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
 344     BasicType bt = (BasicType)i;
 345     if (!is_reference_type(bt)) {
 346       oop m = java_lang_Class::create_basic_type_mirror(type2name(bt), bt, CHECK);
 347       _scratch_basic_type_mirrors[i] = OopHandle(Universe::vm_global(), m);
 348     }
 349   }
 350   _scratch_java_mirror_table = new (mtClass)KlassToOopHandleTable();
 351 }
 352 
 353 oop HeapShared::scratch_java_mirror(BasicType t) {
 354   assert((uint)t < T_VOID+1, "range check");
 355   assert(!is_reference_type(t), "sanity");
 356   return _scratch_basic_type_mirrors[t].resolve();
 357 }
 358 
 359 oop HeapShared::scratch_java_mirror(Klass* k) {
 360   return _scratch_java_mirror_table->get_oop(k);
 361 }
 362 
 363 void HeapShared::set_scratch_java_mirror(Klass* k, oop mirror) {
 364   _scratch_java_mirror_table->set_oop(k, mirror);
 365 }
 366 
 367 void HeapShared::remove_scratch_objects(Klass* k) {
 368   _scratch_java_mirror_table->remove_oop(k);
 369 }
 370 
 371 void HeapShared::archive_java_mirrors() {
 372   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
 373     BasicType bt = (BasicType)i;
 374     if (!is_reference_type(bt)) {
 375       oop m = _scratch_basic_type_mirrors[i].resolve();
 376       assert(m != nullptr, "sanity");
 377       bool success = archive_reachable_objects_from(1, _default_subgraph_info, m);
 378       assert(success, "sanity");
 379 
 380       log_trace(cds, heap, mirror)(
 381         "Archived %s mirror object from " PTR_FORMAT,
 382         type2name(bt), p2i(m));
 383 
 384       Universe::set_archived_basic_type_mirror_index(bt, append_root(m));
 385     }
 386   }
 387 
 388   GrowableArray<Klass*>* klasses = ArchiveBuilder::current()->klasses();
 389   assert(klasses != nullptr, "sanity");
 390   for (int i = 0; i < klasses->length(); i++) {
 391     Klass* orig_k = klasses->at(i);
 392     oop m = scratch_java_mirror(orig_k);
 393     if (m != nullptr) {
 394       Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
 395       bool success = archive_reachable_objects_from(1, _default_subgraph_info, m);
 396       guarantee(success, "scratch mirrors must point to only archivable objects");
 397       buffered_k->set_archived_java_mirror(append_root(m));
 398       ResourceMark rm;
 399       log_trace(cds, heap, mirror)(
 400         "Archived %s mirror object from " PTR_FORMAT,
 401         buffered_k->external_name(), p2i(m));
 402 
 403       // archive the resolved_referenes array
 404       if (buffered_k->is_instance_klass()) {
 405         InstanceKlass* ik = InstanceKlass::cast(buffered_k);
 406         oop rr = ik->constants()->prepare_resolved_references_for_archiving();
 407         if (rr != nullptr && !ArchiveHeapWriter::is_too_large_to_archive(rr)) {
 408           bool success = HeapShared::archive_reachable_objects_from(1, _default_subgraph_info, rr);
 409           assert(success, "must be");
 410           int root_index = append_root(rr);
 411           ik->constants()->cache()->set_archived_references(root_index);
 412         }
 413       }
 414     }
 415   }
 416 }
 417 
 418 void HeapShared::archive_strings() {
 419   oop shared_strings_array = StringTable::init_shared_table(_dumped_interned_strings);
 420   bool success = archive_reachable_objects_from(1, _default_subgraph_info, shared_strings_array);
 421   // We must succeed because:
 422   // - _dumped_interned_strings do not contain any large strings.
 423   // - StringTable::init_shared_table() doesn't create any large arrays.
 424   assert(success, "shared strings array must not point to arrays or strings that are too large to archive");
 425   StringTable::set_shared_strings_array_index(append_root(shared_strings_array));
 426 }
 427 
 428 void HeapShared::mark_native_pointers(oop orig_obj) {
 429   if (java_lang_Class::is_instance(orig_obj)) {
 430     ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::klass_offset());
 431     ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::array_klass_offset());
 432   }
 433 }
 434 
 435 // -- Handling of Enum objects
 436 // Java Enum classes have synthetic <clinit> methods that look like this
 437 //     enum MyEnum {FOO, BAR}
 438 //     MyEnum::<clinint> {
 439 //        /*static final MyEnum*/ MyEnum::FOO = new MyEnum("FOO");
 440 //        /*static final MyEnum*/ MyEnum::BAR = new MyEnum("BAR");
 441 //     }
 442 //
 443 // If MyEnum::FOO object is referenced by any of the archived subgraphs, we must
 444 // ensure the archived value equals (in object address) to the runtime value of
 445 // MyEnum::FOO.
 446 //
 447 // However, since MyEnum::<clinint> is synthetically generated by javac, there's
 448 // no way of programmatically handling this inside the Java code (as you would handle
 449 // ModuleLayer::EMPTY_LAYER, for example).
 450 //
 451 // Instead, we archive all static field of such Enum classes. At runtime,
 452 // HeapShared::initialize_enum_klass() will skip the <clinit> method and pull
 453 // the static fields out of the archived heap.
 454 void HeapShared::check_enum_obj(int level,
 455                                 KlassSubGraphInfo* subgraph_info,
 456                                 oop orig_obj) {
 457   assert(level > 1, "must never be called at the first (outermost) level");
 458   Klass* k = orig_obj->klass();
 459   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(k);
 460   if (!k->is_instance_klass()) {
 461     return;
 462   }
 463   InstanceKlass* ik = InstanceKlass::cast(k);
 464   if (ik->java_super() == vmClasses::Enum_klass() && !ik->has_archived_enum_objs()) {
 465     ResourceMark rm;
 466     ik->set_has_archived_enum_objs();
 467     buffered_k->set_has_archived_enum_objs();
 468     oop mirror = ik->java_mirror();
 469 
 470     for (JavaFieldStream fs(ik); !fs.done(); fs.next()) {
 471       if (fs.access_flags().is_static()) {
 472         fieldDescriptor& fd = fs.field_descriptor();
 473         if (fd.field_type() != T_OBJECT && fd.field_type() != T_ARRAY) {
 474           guarantee(false, "static field %s::%s must be T_OBJECT or T_ARRAY",
 475                     ik->external_name(), fd.name()->as_C_string());
 476         }
 477         oop oop_field = mirror->obj_field(fd.offset());
 478         if (oop_field == nullptr) {
 479           guarantee(false, "static field %s::%s must not be null",
 480                     ik->external_name(), fd.name()->as_C_string());
 481         } else if (oop_field->klass() != ik && oop_field->klass() != ik->array_klass_or_null()) {
 482           guarantee(false, "static field %s::%s is of the wrong type",
 483                     ik->external_name(), fd.name()->as_C_string());
 484         }
 485         bool success = archive_reachable_objects_from(level, subgraph_info, oop_field);
 486         assert(success, "VM should have exited with unarchivable objects for _level > 1");
 487         int root_index = append_root(oop_field);
 488         log_info(cds, heap)("Archived enum obj @%d %s::%s (" INTPTR_FORMAT ")",
 489                             root_index, ik->external_name(), fd.name()->as_C_string(),
 490                             p2i((oopDesc*)oop_field));
 491         SystemDictionaryShared::add_enum_klass_static_field(ik, root_index);
 492       }
 493     }
 494   }
 495 }
 496 
 497 // See comments in HeapShared::check_enum_obj()
 498 bool HeapShared::initialize_enum_klass(InstanceKlass* k, TRAPS) {
 499   if (!ArchiveHeapLoader::is_in_use()) {
 500     return false;
 501   }
 502 
 503   RunTimeClassInfo* info = RunTimeClassInfo::get_for(k);
 504   assert(info != nullptr, "sanity");
 505 
 506   if (log_is_enabled(Info, cds, heap)) {
 507     ResourceMark rm;
 508     log_info(cds, heap)("Initializing Enum class: %s", k->external_name());
 509   }
 510 
 511   oop mirror = k->java_mirror();
 512   int i = 0;
 513   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
 514     if (fs.access_flags().is_static()) {
 515       int root_index = info->enum_klass_static_field_root_index_at(i++);
 516       fieldDescriptor& fd = fs.field_descriptor();
 517       assert(fd.field_type() == T_OBJECT || fd.field_type() == T_ARRAY, "must be");
 518       mirror->obj_field_put(fd.offset(), get_root(root_index, /*clear=*/true));
 519     }
 520   }
 521   return true;
 522 }
 523 
 524 void HeapShared::archive_objects(ArchiveHeapInfo *heap_info) {
 525   {
 526     NoSafepointVerifier nsv;
 527 
 528     _default_subgraph_info = init_subgraph_info(vmClasses::Object_klass(), false);
 529 
 530     // Cache for recording where the archived objects are copied to
 531     create_archived_object_cache();
 532 
 533     log_info(cds)("Heap range = [" PTR_FORMAT " - "  PTR_FORMAT "]",
 534                    UseCompressedOops ? p2i(CompressedOops::begin()) :
 535                                        p2i((address)G1CollectedHeap::heap()->reserved().start()),
 536                    UseCompressedOops ? p2i(CompressedOops::end()) :
 537                                        p2i((address)G1CollectedHeap::heap()->reserved().end()));
 538     copy_objects();
 539 
 540     CDSHeapVerifier::verify();
 541     check_default_subgraph_classes();
 542   }
 543 
 544   ArchiveHeapWriter::write(_pending_roots, heap_info);
 545 }
 546 
 547 void HeapShared::copy_interned_strings() {
 548   init_seen_objects_table();
 549 
 550   auto copier = [&] (oop s, bool value_ignored) {
 551     assert(s != nullptr, "sanity");
 552     assert(!ArchiveHeapWriter::is_string_too_large_to_archive(s), "large strings must have been filtered");
 553     bool success = archive_reachable_objects_from(1, _default_subgraph_info, s);
 554     assert(success, "must be");
 555     // Prevent string deduplication from changing the value field to
 556     // something not in the archive.
 557     java_lang_String::set_deduplication_forbidden(s);
 558   };
 559   _dumped_interned_strings->iterate_all(copier);
 560 
 561   delete_seen_objects_table();
 562 }
 563 
 564 void HeapShared::copy_special_objects() {
 565   // Archive special objects that do not belong to any subgraphs
 566   init_seen_objects_table();
 567   archive_java_mirrors();
 568   archive_strings();
 569   delete_seen_objects_table();
 570 }
 571 
 572 void HeapShared::copy_objects() {
 573   assert(HeapShared::can_write(), "must be");
 574 
 575   copy_interned_strings();
 576   copy_special_objects();
 577 
 578   archive_object_subgraphs(archive_subgraph_entry_fields,
 579                            false /* is_full_module_graph */);
 580 
 581   if (MetaspaceShared::use_full_module_graph()) {
 582     archive_object_subgraphs(fmg_archive_subgraph_entry_fields,
 583                              true /* is_full_module_graph */);
 584     Modules::verify_archived_modules();
 585   }
 586 }
 587 
 588 //
 589 // Subgraph archiving support
 590 //
 591 HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = nullptr;
 592 HeapShared::RunTimeKlassSubGraphInfoTable   HeapShared::_run_time_subgraph_info_table;
 593 
 594 // Get the subgraph_info for Klass k. A new subgraph_info is created if
 595 // there is no existing one for k. The subgraph_info records the "buffered"
 596 // address of the class.
 597 KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
 598   assert(DumpSharedSpaces, "dump time only");
 599   bool created;
 600   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(k);
 601   KlassSubGraphInfo* info =
 602     _dump_time_subgraph_info_table->put_if_absent(k, KlassSubGraphInfo(buffered_k, is_full_module_graph),
 603                                                   &created);
 604   assert(created, "must not initialize twice");
 605   return info;
 606 }
 607 
 608 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
 609   assert(DumpSharedSpaces, "dump time only");
 610   KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
 611   assert(info != nullptr, "must have been initialized");
 612   return info;
 613 }
 614 
 615 // Add an entry field to the current KlassSubGraphInfo.
 616 void KlassSubGraphInfo::add_subgraph_entry_field(int static_field_offset, oop v) {
 617   assert(DumpSharedSpaces, "dump time only");
 618   if (_subgraph_entry_fields == nullptr) {
 619     _subgraph_entry_fields =
 620       new (mtClass) GrowableArray<int>(10, mtClass);
 621   }
 622   _subgraph_entry_fields->append(static_field_offset);
 623   _subgraph_entry_fields->append(HeapShared::append_root(v));
 624 }
 625 
 626 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
 627 // Only objects of boot classes can be included in sub-graph.
 628 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
 629   assert(DumpSharedSpaces, "dump time only");
 630   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
 631 
 632   if (_subgraph_object_klasses == nullptr) {
 633     _subgraph_object_klasses =
 634       new (mtClass) GrowableArray<Klass*>(50, mtClass);
 635   }
 636 
 637   assert(ArchiveBuilder::current()->is_in_buffer_space(buffered_k), "must be a shared class");
 638 
 639   if (_k == buffered_k) {
 640     // Don't add the Klass containing the sub-graph to it's own klass
 641     // initialization list.
 642     return;
 643   }
 644 
 645   if (buffered_k->is_instance_klass()) {
 646     assert(InstanceKlass::cast(buffered_k)->is_shared_boot_class(),
 647           "must be boot class");
 648     // vmClasses::xxx_klass() are not updated, need to check
 649     // the original Klass*
 650     if (orig_k == vmClasses::String_klass() ||
 651         orig_k == vmClasses::Object_klass()) {
 652       // Initialized early during VM initialization. No need to be added
 653       // to the sub-graph object class list.
 654       return;
 655     }
 656     check_allowed_klass(InstanceKlass::cast(orig_k));
 657   } else if (buffered_k->is_objArray_klass()) {
 658     Klass* abk = ObjArrayKlass::cast(buffered_k)->bottom_klass();
 659     if (abk->is_instance_klass()) {
 660       assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
 661             "must be boot class");
 662       check_allowed_klass(InstanceKlass::cast(ObjArrayKlass::cast(orig_k)->bottom_klass()));
 663     }
 664     if (buffered_k == Universe::objectArrayKlassObj()) {
 665       // Initialized early during Universe::genesis. No need to be added
 666       // to the list.
 667       return;
 668     }
 669   } else {
 670     assert(buffered_k->is_typeArray_klass(), "must be");
 671     // Primitive type arrays are created early during Universe::genesis.
 672     return;
 673   }
 674 
 675   if (log_is_enabled(Debug, cds, heap)) {
 676     if (!_subgraph_object_klasses->contains(buffered_k)) {
 677       ResourceMark rm;
 678       log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
 679     }
 680   }
 681 
 682   _subgraph_object_klasses->append_if_missing(buffered_k);
 683   _has_non_early_klasses |= is_non_early_klass(orig_k);
 684 }
 685 
 686 void KlassSubGraphInfo::check_allowed_klass(InstanceKlass* ik) {
 687   if (ik->module()->name() == vmSymbols::java_base()) {
 688     assert(ik->package() != nullptr, "classes in java.base cannot be in unnamed package");
 689     return;
 690   }
 691 
 692 #ifndef PRODUCT
 693   if (!ik->module()->is_named() && ik->package() == nullptr) {
 694     // This class is loaded by ArchiveHeapTestClass
 695     return;
 696   }
 697   const char* extra_msg = ", or in an unnamed package of an unnamed module";
 698 #else
 699   const char* extra_msg = "";
 700 #endif
 701 
 702   ResourceMark rm;
 703   log_error(cds, heap)("Class %s not allowed in archive heap. Must be in java.base%s",
 704                        ik->external_name(), extra_msg);
 705   MetaspaceShared::unrecoverable_writing_error();
 706 }
 707 
 708 bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
 709   if (k->is_objArray_klass()) {
 710     k = ObjArrayKlass::cast(k)->bottom_klass();
 711   }
 712   if (k->is_instance_klass()) {
 713     if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
 714       ResourceMark rm;
 715       log_info(cds, heap)("non-early: %s", k->external_name());
 716       return true;
 717     } else {
 718       return false;
 719     }
 720   } else {
 721     return false;
 722   }
 723 }
 724 
 725 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
 726 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
 727   _k = info->klass();
 728   _entry_field_records = nullptr;
 729   _subgraph_object_klasses = nullptr;
 730   _is_full_module_graph = info->is_full_module_graph();
 731 
 732   if (_is_full_module_graph) {
 733     // Consider all classes referenced by the full module graph as early -- we will be
 734     // allocating objects of these classes during JVMTI early phase, so they cannot
 735     // be processed by (non-early) JVMTI ClassFileLoadHook
 736     _has_non_early_klasses = false;
 737   } else {
 738     _has_non_early_klasses = info->has_non_early_klasses();
 739   }
 740 
 741   if (_has_non_early_klasses) {
 742     ResourceMark rm;
 743     log_info(cds, heap)(
 744           "Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
 745           _k->external_name());
 746   }
 747 
 748   // populate the entry fields
 749   GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
 750   if (entry_fields != nullptr) {
 751     int num_entry_fields = entry_fields->length();
 752     assert(num_entry_fields % 2 == 0, "sanity");
 753     _entry_field_records =
 754       ArchiveBuilder::new_ro_array<int>(num_entry_fields);
 755     for (int i = 0 ; i < num_entry_fields; i++) {
 756       _entry_field_records->at_put(i, entry_fields->at(i));
 757     }
 758   }
 759 
 760   // the Klasses of the objects in the sub-graphs
 761   GrowableArray<Klass*>* subgraph_object_klasses = info->subgraph_object_klasses();
 762   if (subgraph_object_klasses != nullptr) {
 763     int num_subgraphs_klasses = subgraph_object_klasses->length();
 764     _subgraph_object_klasses =
 765       ArchiveBuilder::new_ro_array<Klass*>(num_subgraphs_klasses);
 766     for (int i = 0; i < num_subgraphs_klasses; i++) {
 767       Klass* subgraph_k = subgraph_object_klasses->at(i);
 768       if (log_is_enabled(Info, cds, heap)) {
 769         ResourceMark rm;
 770         log_info(cds, heap)(
 771           "Archived object klass %s (%2d) => %s",
 772           _k->external_name(), i, subgraph_k->external_name());
 773       }
 774       _subgraph_object_klasses->at_put(i, subgraph_k);
 775       ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(i));
 776     }
 777   }
 778 
 779   ArchivePtrMarker::mark_pointer(&_k);
 780   ArchivePtrMarker::mark_pointer(&_entry_field_records);
 781   ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
 782 }
 783 
 784 struct CopyKlassSubGraphInfoToArchive : StackObj {
 785   CompactHashtableWriter* _writer;
 786   CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
 787 
 788   bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
 789     if (info.subgraph_object_klasses() != nullptr || info.subgraph_entry_fields() != nullptr) {
 790       ArchivedKlassSubGraphInfoRecord* record =
 791         (ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
 792       record->init(&info);
 793 
 794       Klass* buffered_k = ArchiveBuilder::get_buffered_klass(klass);
 795       unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary((address)buffered_k);
 796       u4 delta = ArchiveBuilder::current()->any_to_offset_u4(record);
 797       _writer->add(hash, delta);
 798     }
 799     return true; // keep on iterating
 800   }
 801 };
 802 
 803 // Build the records of archived subgraph infos, which include:
 804 // - Entry points to all subgraphs from the containing class mirror. The entry
 805 //   points are static fields in the mirror. For each entry point, the field
 806 //   offset, and value are recorded in the sub-graph
 807 //   info. The value is stored back to the corresponding field at runtime.
 808 // - A list of klasses that need to be loaded/initialized before archived
 809 //   java object sub-graph can be accessed at runtime.
 810 void HeapShared::write_subgraph_info_table() {
 811   // Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
 812   DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
 813   CompactHashtableStats stats;
 814 
 815   _run_time_subgraph_info_table.reset();
 816 
 817   CompactHashtableWriter writer(d_table->_count, &stats);
 818   CopyKlassSubGraphInfoToArchive copy(&writer);
 819   d_table->iterate(&copy);
 820   writer.dump(&_run_time_subgraph_info_table, "subgraphs");
 821 
 822 #ifndef PRODUCT
 823   if (ArchiveHeapTestClass != nullptr) {
 824     size_t len = strlen(ArchiveHeapTestClass) + 1;
 825     Array<char>* array = ArchiveBuilder::new_ro_array<char>((int)len);
 826     strncpy(array->adr_at(0), ArchiveHeapTestClass, len);
 827     _archived_ArchiveHeapTestClass = array;
 828   }
 829 #endif
 830   if (log_is_enabled(Info, cds, heap)) {
 831     print_stats();
 832   }
 833 }
 834 
 835 void HeapShared::serialize_root(SerializeClosure* soc) {
 836   oop roots_oop = nullptr;
 837 
 838   if (soc->reading()) {
 839     soc->do_oop(&roots_oop); // read from archive
 840     assert(oopDesc::is_oop_or_null(roots_oop), "is oop");
 841     // Create an OopHandle only if we have actually mapped or loaded the roots
 842     if (roots_oop != nullptr) {
 843       assert(ArchiveHeapLoader::is_in_use(), "must be");
 844       _roots = OopHandle(Universe::vm_global(), roots_oop);
 845     }
 846   } else {
 847     // writing
 848     if (HeapShared::can_write()) {
 849       roots_oop = ArchiveHeapWriter::heap_roots_requested_address();
 850     }
 851     soc->do_oop(&roots_oop); // write to archive
 852   }
 853 }
 854 
 855 void HeapShared::serialize_tables(SerializeClosure* soc) {
 856 
 857 #ifndef PRODUCT
 858   soc->do_ptr((void**)&_archived_ArchiveHeapTestClass);
 859   if (soc->reading() && _archived_ArchiveHeapTestClass != nullptr) {
 860     _test_class_name = _archived_ArchiveHeapTestClass->adr_at(0);
 861     setup_test_class(_test_class_name);
 862   }
 863 #endif
 864 
 865   _run_time_subgraph_info_table.serialize_header(soc);
 866 }
 867 
 868 static void verify_the_heap(Klass* k, const char* which) {
 869   if (VerifyArchivedFields > 0) {
 870     ResourceMark rm;
 871     log_info(cds, heap)("Verify heap %s initializing static field(s) in %s",
 872                         which, k->external_name());
 873 
 874     VM_Verify verify_op;
 875     VMThread::execute(&verify_op);
 876 
 877     if (VerifyArchivedFields > 1 && is_init_completed()) {
 878       // At this time, the oop->klass() of some archived objects in the heap may not
 879       // have been loaded into the system dictionary yet. Nevertheless, oop->klass() should
 880       // have enough information (object size, oop maps, etc) so that a GC can be safely
 881       // performed.
 882       //
 883       // -XX:VerifyArchivedFields=2 force a GC to happen in such an early stage
 884       // to check for GC safety.
 885       log_info(cds, heap)("Trigger GC %s initializing static field(s) in %s",
 886                           which, k->external_name());
 887       FlagSetting fs1(VerifyBeforeGC, true);
 888       FlagSetting fs2(VerifyDuringGC, true);
 889       FlagSetting fs3(VerifyAfterGC,  true);
 890       Universe::heap()->collect(GCCause::_java_lang_system_gc);
 891     }
 892   }
 893 }
 894 
 895 // Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
 896 // have a valid klass. I.e., oopDesc::klass() must have already been resolved.
 897 //
 898 // Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
 899 // ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
 900 // this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
 901 void HeapShared::resolve_classes(JavaThread* current) {
 902   assert(UseSharedSpaces, "runtime only!");
 903   if (!ArchiveHeapLoader::is_in_use()) {
 904     return; // nothing to do
 905   }
 906   resolve_classes_for_subgraphs(current, archive_subgraph_entry_fields);
 907   resolve_classes_for_subgraphs(current, fmg_archive_subgraph_entry_fields);
 908 }
 909 
 910 void HeapShared::resolve_classes_for_subgraphs(JavaThread* current, ArchivableStaticFieldInfo fields[]) {
 911   for (int i = 0; fields[i].valid(); i++) {
 912     ArchivableStaticFieldInfo* info = &fields[i];
 913     TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
 914     InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
 915     assert(k != nullptr && k->is_shared_boot_class(), "sanity");
 916     resolve_classes_for_subgraph_of(current, k);
 917   }
 918 }
 919 
 920 void HeapShared::resolve_classes_for_subgraph_of(JavaThread* current, Klass* k) {
 921   JavaThread* THREAD = current;
 922   ExceptionMark em(THREAD);
 923   const ArchivedKlassSubGraphInfoRecord* record =
 924    resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
 925   if (HAS_PENDING_EXCEPTION) {
 926    CLEAR_PENDING_EXCEPTION;
 927   }
 928   if (record == nullptr) {
 929    clear_archived_roots_of(k);
 930   }
 931 }
 932 
 933 void HeapShared::initialize_from_archived_subgraph(JavaThread* current, Klass* k) {
 934   JavaThread* THREAD = current;
 935   if (!ArchiveHeapLoader::is_in_use()) {
 936     return; // nothing to do
 937   }
 938 
 939   ExceptionMark em(THREAD);
 940   const ArchivedKlassSubGraphInfoRecord* record =
 941     resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
 942 
 943   if (HAS_PENDING_EXCEPTION) {
 944     CLEAR_PENDING_EXCEPTION;
 945     // None of the field value will be set if there was an exception when initializing the classes.
 946     // The java code will not see any of the archived objects in the
 947     // subgraphs referenced from k in this case.
 948     return;
 949   }
 950 
 951   if (record != nullptr) {
 952     init_archived_fields_for(k, record);
 953   }
 954 }
 955 
 956 const ArchivedKlassSubGraphInfoRecord*
 957 HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
 958   assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
 959 
 960   if (!k->is_shared()) {
 961     return nullptr;
 962   }
 963   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
 964   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 965 
 966 #ifndef PRODUCT
 967   if (_test_class_name != nullptr && k->name()->equals(_test_class_name) && record != nullptr) {
 968     _test_class = k;
 969     _test_class_record = record;
 970   }
 971 #endif
 972 
 973   // Initialize from archived data. Currently this is done only
 974   // during VM initialization time. No lock is needed.
 975   if (record != nullptr) {
 976     if (record->is_full_module_graph() && !MetaspaceShared::use_full_module_graph()) {
 977       if (log_is_enabled(Info, cds, heap)) {
 978         ResourceMark rm(THREAD);
 979         log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
 980                             k->external_name());
 981       }
 982       return nullptr;
 983     }
 984 
 985     if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
 986       if (log_is_enabled(Info, cds, heap)) {
 987         ResourceMark rm(THREAD);
 988         log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
 989                             k->external_name());
 990       }
 991       return nullptr;
 992     }
 993 
 994     if (log_is_enabled(Info, cds, heap)) {
 995       ResourceMark rm;
 996       log_info(cds, heap)("%s subgraph %s ", do_init ? "init" : "resolve", k->external_name());
 997     }
 998 
 999     resolve_or_init(k, do_init, CHECK_NULL);
1000 
1001     // Load/link/initialize the klasses of the objects in the subgraph.
1002     // nullptr class loader is used.
1003     Array<Klass*>* klasses = record->subgraph_object_klasses();
1004     if (klasses != nullptr) {
1005       for (int i = 0; i < klasses->length(); i++) {
1006         Klass* klass = klasses->at(i);
1007         if (!klass->is_shared()) {
1008           return nullptr;
1009         }
1010         resolve_or_init(klass, do_init, CHECK_NULL);
1011       }
1012     }
1013   }
1014 
1015   return record;
1016 }
1017 
1018 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
1019   if (!do_init) {
1020     if (k->class_loader_data() == nullptr) {
1021       Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
1022       assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
1023     }
1024   } else {
1025     assert(k->class_loader_data() != nullptr, "must have been resolved by HeapShared::resolve_classes");
1026     if (k->is_instance_klass()) {
1027       InstanceKlass* ik = InstanceKlass::cast(k);
1028       ik->initialize(CHECK);
1029     } else if (k->is_objArray_klass()) {
1030       ObjArrayKlass* oak = ObjArrayKlass::cast(k);
1031       oak->initialize(CHECK);
1032     }
1033   }
1034 }
1035 
1036 void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record) {
1037   verify_the_heap(k, "before");
1038 
1039   // Load the subgraph entry fields from the record and store them back to
1040   // the corresponding fields within the mirror.
1041   oop m = k->java_mirror();
1042   Array<int>* entry_field_records = record->entry_field_records();
1043   if (entry_field_records != nullptr) {
1044     int efr_len = entry_field_records->length();
1045     assert(efr_len % 2 == 0, "sanity");
1046     for (int i = 0; i < efr_len; i += 2) {
1047       int field_offset = entry_field_records->at(i);
1048       int root_index = entry_field_records->at(i+1);
1049       oop v = get_root(root_index, /*clear=*/true);
1050       m->obj_field_put(field_offset, v);
1051       log_debug(cds, heap)("  " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
1052     }
1053 
1054     // Done. Java code can see the archived sub-graphs referenced from k's
1055     // mirror after this point.
1056     if (log_is_enabled(Info, cds, heap)) {
1057       ResourceMark rm;
1058       log_info(cds, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s",
1059                           k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "");
1060     }
1061   }
1062 
1063   verify_the_heap(k, "after ");
1064 }
1065 
1066 void HeapShared::clear_archived_roots_of(Klass* k) {
1067   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
1068   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
1069   if (record != nullptr) {
1070     Array<int>* entry_field_records = record->entry_field_records();
1071     if (entry_field_records != nullptr) {
1072       int efr_len = entry_field_records->length();
1073       assert(efr_len % 2 == 0, "sanity");
1074       for (int i = 0; i < efr_len; i += 2) {
1075         int root_index = entry_field_records->at(i+1);
1076         clear_root(root_index);
1077       }
1078     }
1079   }
1080 }
1081 
1082 class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
1083   int _level;
1084   bool _record_klasses_only;
1085   KlassSubGraphInfo* _subgraph_info;
1086   oop _referencing_obj;
1087 
1088   // The following are for maintaining a stack for determining
1089   // CachedOopInfo::_referrer
1090   static WalkOopAndArchiveClosure* _current;
1091   WalkOopAndArchiveClosure* _last;
1092  public:
1093   WalkOopAndArchiveClosure(int level,
1094                            bool record_klasses_only,
1095                            KlassSubGraphInfo* subgraph_info,
1096                            oop orig) :
1097     _level(level),
1098     _record_klasses_only(record_klasses_only),
1099     _subgraph_info(subgraph_info),
1100     _referencing_obj(orig) {
1101     _last = _current;
1102     _current = this;
1103   }
1104   ~WalkOopAndArchiveClosure() {
1105     _current = _last;
1106   }
1107   void do_oop(narrowOop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
1108   void do_oop(      oop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
1109 
1110  protected:
1111   template <class T> void do_oop_work(T *p) {
1112     oop obj = RawAccess<>::oop_load(p);
1113     if (!CompressedOops::is_null(obj)) {
1114       size_t field_delta = pointer_delta(p, _referencing_obj, sizeof(char));
1115 
1116       if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
1117         ResourceMark rm;
1118         log_debug(cds, heap)("(%d) %s[" SIZE_FORMAT "] ==> " PTR_FORMAT " size " SIZE_FORMAT " %s", _level,
1119                              _referencing_obj->klass()->external_name(), field_delta,
1120                              p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
1121         if (log_is_enabled(Trace, cds, heap)) {
1122           LogTarget(Trace, cds, heap) log;
1123           LogStream out(log);
1124           obj->print_on(&out);
1125         }
1126       }
1127 
1128       bool success = HeapShared::archive_reachable_objects_from(
1129           _level + 1, _subgraph_info, obj);
1130       assert(success, "VM should have exited with unarchivable objects for _level > 1");
1131     }
1132   }
1133 
1134  public:
1135   static WalkOopAndArchiveClosure* current()  { return _current;              }
1136   oop referencing_obj()                       { return _referencing_obj;      }
1137   KlassSubGraphInfo* subgraph_info()          { return _subgraph_info;        }
1138 };
1139 
1140 WalkOopAndArchiveClosure* WalkOopAndArchiveClosure::_current = nullptr;
1141 
1142 HeapShared::CachedOopInfo HeapShared::make_cached_oop_info() {
1143   WalkOopAndArchiveClosure* walker = WalkOopAndArchiveClosure::current();
1144   oop referrer = (walker == nullptr) ? nullptr : walker->referencing_obj();
1145   return CachedOopInfo(referrer);
1146 }
1147 
1148 // (1) If orig_obj has not been archived yet, archive it.
1149 // (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
1150 //     trace all  objects that are reachable from it, and make sure these objects are archived.
1151 // (3) Record the klasses of all orig_obj and all reachable objects.
1152 bool HeapShared::archive_reachable_objects_from(int level,
1153                                                 KlassSubGraphInfo* subgraph_info,
1154                                                 oop orig_obj) {
1155   assert(orig_obj != nullptr, "must be");
1156 
1157   if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
1158     // This object has injected fields that cannot be supported easily, so we disallow them for now.
1159     // If you get an error here, you probably made a change in the JDK library that has added
1160     // these objects that are referenced (directly or indirectly) by static fields.
1161     ResourceMark rm;
1162     log_error(cds, heap)("Cannot archive object of class %s", orig_obj->klass()->external_name());
1163     MetaspaceShared::unrecoverable_writing_error();
1164   }
1165 
1166   // java.lang.Class instances cannot be included in an archived object sub-graph. We only support
1167   // them as Klass::_archived_mirror because they need to be specially restored at run time.
1168   //
1169   // If you get an error here, you probably made a change in the JDK library that has added a Class
1170   // object that is referenced (directly or indirectly) by static fields.
1171   if (java_lang_Class::is_instance(orig_obj) && subgraph_info != _default_subgraph_info) {
1172     log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
1173     MetaspaceShared::unrecoverable_writing_error();
1174   }
1175 
1176   if (has_been_seen_during_subgraph_recording(orig_obj)) {
1177     // orig_obj has already been archived and traced. Nothing more to do.
1178     return true;
1179   } else {
1180     set_has_been_seen_during_subgraph_recording(orig_obj);
1181   }
1182 
1183   bool already_archived = has_been_archived(orig_obj);
1184   bool record_klasses_only = already_archived;
1185   if (!already_archived) {
1186     ++_num_new_archived_objs;
1187     if (!archive_object(orig_obj)) {
1188       // Skip archiving the sub-graph referenced from the current entry field.
1189       ResourceMark rm;
1190       log_error(cds, heap)(
1191         "Cannot archive the sub-graph referenced from %s object ("
1192         PTR_FORMAT ") size " SIZE_FORMAT ", skipped.",
1193         orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
1194       if (level == 1) {
1195         // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1196         // as the Java code will take care of initializing this field dynamically.
1197         return false;
1198       } else {
1199         // We don't know how to handle an object that has been archived, but some of its reachable
1200         // objects cannot be archived. Bail out for now. We might need to fix this in the future if
1201         // we have a real use case.
1202         MetaspaceShared::unrecoverable_writing_error();
1203       }
1204     }
1205   }
1206 
1207   Klass *orig_k = orig_obj->klass();
1208   subgraph_info->add_subgraph_object_klass(orig_k);
1209 
1210   WalkOopAndArchiveClosure walker(level, record_klasses_only, subgraph_info, orig_obj);
1211   orig_obj->oop_iterate(&walker);
1212 
1213   check_enum_obj(level + 1, subgraph_info, orig_obj);
1214   return true;
1215 }
1216 
1217 //
1218 // Start from the given static field in a java mirror and archive the
1219 // complete sub-graph of java heap objects that are reached directly
1220 // or indirectly from the starting object by following references.
1221 // Sub-graph archiving restrictions (current):
1222 //
1223 // - All classes of objects in the archived sub-graph (including the
1224 //   entry class) must be boot class only.
1225 // - No java.lang.Class instance (java mirror) can be included inside
1226 //   an archived sub-graph. Mirror can only be the sub-graph entry object.
1227 //
1228 // The Java heap object sub-graph archiving process (see
1229 // WalkOopAndArchiveClosure):
1230 //
1231 // 1) Java object sub-graph archiving starts from a given static field
1232 // within a Class instance (java mirror). If the static field is a
1233 // reference field and points to a non-null java object, proceed to
1234 // the next step.
1235 //
1236 // 2) Archives the referenced java object. If an archived copy of the
1237 // current object already exists, updates the pointer in the archived
1238 // copy of the referencing object to point to the current archived object.
1239 // Otherwise, proceed to the next step.
1240 //
1241 // 3) Follows all references within the current java object and recursively
1242 // archive the sub-graph of objects starting from each reference.
1243 //
1244 // 4) Updates the pointer in the archived copy of referencing object to
1245 // point to the current archived object.
1246 //
1247 // 5) The Klass of the current java object is added to the list of Klasses
1248 // for loading and initializing before any object in the archived graph can
1249 // be accessed at runtime.
1250 //
1251 void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
1252                                                              const char* klass_name,
1253                                                              int field_offset,
1254                                                              const char* field_name) {
1255   assert(DumpSharedSpaces, "dump time only");
1256   assert(k->is_shared_boot_class(), "must be boot class");
1257 
1258   oop m = k->java_mirror();
1259 
1260   KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
1261   oop f = m->obj_field(field_offset);
1262 
1263   log_debug(cds, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
1264 
1265   if (!CompressedOops::is_null(f)) {
1266     if (log_is_enabled(Trace, cds, heap)) {
1267       LogTarget(Trace, cds, heap) log;
1268       LogStream out(log);
1269       f->print_on(&out);
1270     }
1271 
1272     bool success = archive_reachable_objects_from(1, subgraph_info, f);
1273     if (!success) {
1274       log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
1275                            klass_name, field_name);
1276     } else {
1277       // Note: the field value is not preserved in the archived mirror.
1278       // Record the field as a new subGraph entry point. The recorded
1279       // information is restored from the archive at runtime.
1280       subgraph_info->add_subgraph_entry_field(field_offset, f);
1281       log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(f));
1282     }
1283   } else {
1284     // The field contains null, we still need to record the entry point,
1285     // so it can be restored at runtime.
1286     subgraph_info->add_subgraph_entry_field(field_offset, nullptr);
1287   }
1288 }
1289 
1290 #ifndef PRODUCT
1291 class VerifySharedOopClosure: public BasicOopIterateClosure {
1292  public:
1293   void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
1294   void do_oop(      oop *p) { VerifySharedOopClosure::do_oop_work(p); }
1295 
1296  protected:
1297   template <class T> void do_oop_work(T *p) {
1298     oop obj = RawAccess<>::oop_load(p);
1299     if (!CompressedOops::is_null(obj)) {
1300       HeapShared::verify_reachable_objects_from(obj);
1301     }
1302   }
1303 };
1304 
1305 void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
1306   assert(DumpSharedSpaces, "dump time only");
1307   assert(k->is_shared_boot_class(), "must be boot class");
1308 
1309   oop m = k->java_mirror();
1310   oop f = m->obj_field(field_offset);
1311   if (!CompressedOops::is_null(f)) {
1312     verify_subgraph_from(f);
1313   }
1314 }
1315 
1316 void HeapShared::verify_subgraph_from(oop orig_obj) {
1317   if (!has_been_archived(orig_obj)) {
1318     // It's OK for the root of a subgraph to be not archived. See comments in
1319     // archive_reachable_objects_from().
1320     return;
1321   }
1322 
1323   // Verify that all objects reachable from orig_obj are archived.
1324   init_seen_objects_table();
1325   verify_reachable_objects_from(orig_obj);
1326   delete_seen_objects_table();
1327 }
1328 
1329 void HeapShared::verify_reachable_objects_from(oop obj) {
1330   _num_total_verifications ++;
1331   if (!has_been_seen_during_subgraph_recording(obj)) {
1332     set_has_been_seen_during_subgraph_recording(obj);
1333     assert(has_been_archived(obj), "must be");
1334     VerifySharedOopClosure walker;
1335     obj->oop_iterate(&walker);
1336   }
1337 }
1338 #endif
1339 
1340 // The "default subgraph" contains special objects (see heapShared.hpp) that
1341 // can be accessed before we load any Java classes (including java/lang/Class).
1342 // Make sure that these are only instances of the very few specific types
1343 // that we can handle.
1344 void HeapShared::check_default_subgraph_classes() {
1345   GrowableArray<Klass*>* klasses = _default_subgraph_info->subgraph_object_klasses();
1346   int num = klasses->length();
1347   for (int i = 0; i < num; i++) {
1348     Klass* subgraph_k = klasses->at(i);
1349     if (log_is_enabled(Info, cds, heap)) {
1350       ResourceMark rm;
1351       log_info(cds, heap)(
1352           "Archived object klass (default subgraph %d) => %s",
1353           i, subgraph_k->external_name());
1354     }
1355 
1356     guarantee(subgraph_k->name()->equals("java/lang/Class") ||
1357               subgraph_k->name()->equals("java/lang/String") ||
1358               subgraph_k->name()->equals("[Ljava/lang/Object;") ||
1359               subgraph_k->name()->equals("[C") ||
1360               subgraph_k->name()->equals("[B"),
1361               "default subgraph can have only these objects");
1362   }
1363 }
1364 
1365 HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = nullptr;
1366 int HeapShared::_num_new_walked_objs;
1367 int HeapShared::_num_new_archived_objs;
1368 int HeapShared::_num_old_recorded_klasses;
1369 
1370 int HeapShared::_num_total_subgraph_recordings = 0;
1371 int HeapShared::_num_total_walked_objs = 0;
1372 int HeapShared::_num_total_archived_objs = 0;
1373 int HeapShared::_num_total_recorded_klasses = 0;
1374 int HeapShared::_num_total_verifications = 0;
1375 
1376 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
1377   return _seen_objects_table->get(obj) != nullptr;
1378 }
1379 
1380 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
1381   assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
1382   _seen_objects_table->put(obj, true);
1383   ++ _num_new_walked_objs;
1384 }
1385 
1386 void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
1387   log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
1388   init_subgraph_info(k, is_full_module_graph);
1389   init_seen_objects_table();
1390   _num_new_walked_objs = 0;
1391   _num_new_archived_objs = 0;
1392   _num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
1393 }
1394 
1395 void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
1396   int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
1397     _num_old_recorded_klasses;
1398   log_info(cds, heap)("Done recording subgraph(s) for archived fields in %s: "
1399                       "walked %d objs, archived %d new objs, recorded %d classes",
1400                       class_name, _num_new_walked_objs, _num_new_archived_objs,
1401                       num_new_recorded_klasses);
1402 
1403   delete_seen_objects_table();
1404 
1405   _num_total_subgraph_recordings ++;
1406   _num_total_walked_objs      += _num_new_walked_objs;
1407   _num_total_archived_objs    += _num_new_archived_objs;
1408   _num_total_recorded_klasses +=  num_new_recorded_klasses;
1409 }
1410 
1411 class ArchivableStaticFieldFinder: public FieldClosure {
1412   InstanceKlass* _ik;
1413   Symbol* _field_name;
1414   bool _found;
1415   int _offset;
1416 public:
1417   ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
1418     _ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
1419 
1420   virtual void do_field(fieldDescriptor* fd) {
1421     if (fd->name() == _field_name) {
1422       assert(!_found, "fields can never be overloaded");
1423       if (is_reference_type(fd->field_type())) {
1424         _found = true;
1425         _offset = fd->offset();
1426       }
1427     }
1428   }
1429   bool found()     { return _found;  }
1430   int offset()     { return _offset; }
1431 };
1432 
1433 void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
1434                                             TRAPS) {
1435   for (int i = 0; fields[i].valid(); i++) {
1436     ArchivableStaticFieldInfo* info = &fields[i];
1437     TempNewSymbol klass_name =  SymbolTable::new_symbol(info->klass_name);
1438     TempNewSymbol field_name =  SymbolTable::new_symbol(info->field_name);
1439     ResourceMark rm; // for stringStream::as_string() etc.
1440 
1441 #ifndef PRODUCT
1442     bool is_test_class = (ArchiveHeapTestClass != nullptr) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
1443 #else
1444     bool is_test_class = false;
1445 #endif
1446 
1447     if (is_test_class) {
1448       log_warning(cds)("Loading ArchiveHeapTestClass %s ...", ArchiveHeapTestClass);
1449     }
1450 
1451     Klass* k = SystemDictionary::resolve_or_fail(klass_name, true, THREAD);
1452     if (HAS_PENDING_EXCEPTION) {
1453       CLEAR_PENDING_EXCEPTION;
1454       stringStream st;
1455       st.print("Fail to initialize archive heap: %s cannot be loaded by the boot loader", info->klass_name);
1456       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1457     }
1458 
1459     if (!k->is_instance_klass()) {
1460       stringStream st;
1461       st.print("Fail to initialize archive heap: %s is not an instance class", info->klass_name);
1462       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1463     }
1464 
1465     InstanceKlass* ik = InstanceKlass::cast(k);
1466     assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
1467            "Only support boot classes");
1468 
1469     if (is_test_class) {
1470       if (ik->module()->is_named()) {
1471         // We don't want ArchiveHeapTestClass to be abused to easily load/initialize arbitrary
1472         // core-lib classes. You need to at least append to the bootclasspath.
1473         stringStream st;
1474         st.print("ArchiveHeapTestClass %s is not in unnamed module", ArchiveHeapTestClass);
1475         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1476       }
1477 
1478       if (ik->package() != nullptr) {
1479         // This restriction makes HeapShared::is_a_test_class_in_unnamed_module() easy.
1480         stringStream st;
1481         st.print("ArchiveHeapTestClass %s is not in unnamed package", ArchiveHeapTestClass);
1482         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1483       }
1484     } else {
1485       if (ik->module()->name() != vmSymbols::java_base()) {
1486         // We don't want to deal with cases when a module is unavailable at runtime.
1487         // FUTURE -- load from archived heap only when module graph has not changed
1488         //           between dump and runtime.
1489         stringStream st;
1490         st.print("%s is not in java.base module", info->klass_name);
1491         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1492       }
1493     }
1494 
1495     if (is_test_class) {
1496       log_warning(cds)("Initializing ArchiveHeapTestClass %s ...", ArchiveHeapTestClass);
1497     }
1498     ik->initialize(CHECK);
1499 
1500     ArchivableStaticFieldFinder finder(ik, field_name);
1501     ik->do_local_static_fields(&finder);
1502     if (!finder.found()) {
1503       stringStream st;
1504       st.print("Unable to find the static T_OBJECT field %s::%s", info->klass_name, info->field_name);
1505       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1506     }
1507 
1508     info->klass = ik;
1509     info->offset = finder.offset();
1510   }
1511 }
1512 
1513 void HeapShared::init_subgraph_entry_fields(TRAPS) {
1514   assert(HeapShared::can_write(), "must be");
1515   _dump_time_subgraph_info_table = new (mtClass)DumpTimeKlassSubGraphInfoTable();
1516   init_subgraph_entry_fields(archive_subgraph_entry_fields, CHECK);
1517   if (MetaspaceShared::use_full_module_graph()) {
1518     init_subgraph_entry_fields(fmg_archive_subgraph_entry_fields, CHECK);
1519   }
1520 }
1521 
1522 #ifndef PRODUCT
1523 void HeapShared::setup_test_class(const char* test_class_name) {
1524   ArchivableStaticFieldInfo* p = archive_subgraph_entry_fields;
1525   int num_slots = sizeof(archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
1526   assert(p[num_slots - 2].klass_name == nullptr, "must have empty slot that's patched below");
1527   assert(p[num_slots - 1].klass_name == nullptr, "must have empty slot that marks the end of the list");
1528 
1529   if (test_class_name != nullptr) {
1530     p[num_slots - 2].klass_name = test_class_name;
1531     p[num_slots - 2].field_name = ARCHIVE_TEST_FIELD_NAME;
1532   }
1533 }
1534 
1535 // See if ik is one of the test classes that are pulled in by -XX:ArchiveHeapTestClass
1536 // during runtime. This may be called before the module system is initialized so
1537 // we cannot rely on InstanceKlass::module(), etc.
1538 bool HeapShared::is_a_test_class_in_unnamed_module(Klass* ik) {
1539   if (_test_class != nullptr) {
1540     if (ik == _test_class) {
1541       return true;
1542     }
1543     Array<Klass*>* klasses = _test_class_record->subgraph_object_klasses();
1544     if (klasses == nullptr) {
1545       return false;
1546     }
1547 
1548     for (int i = 0; i < klasses->length(); i++) {
1549       Klass* k = klasses->at(i);
1550       if (k == ik) {
1551         Symbol* name;
1552         if (k->is_instance_klass()) {
1553           name = InstanceKlass::cast(k)->name();
1554         } else if (k->is_objArray_klass()) {
1555           Klass* bk = ObjArrayKlass::cast(k)->bottom_klass();
1556           if (!bk->is_instance_klass()) {
1557             return false;
1558           }
1559           name = bk->name();
1560         } else {
1561           return false;
1562         }
1563 
1564         // See KlassSubGraphInfo::check_allowed_klass() - only two types of
1565         // classes are allowed:
1566         //   (A) java.base classes (which must not be in the unnamed module)
1567         //   (B) test classes which must be in the unnamed package of the unnamed module.
1568         // So if we see a '/' character in the class name, it must be in (A);
1569         // otherwise it must be in (B).
1570         if (name->index_of_at(0, "/", 1)  >= 0) {
1571           return false; // (A)
1572         }
1573 
1574         return true; // (B)
1575       }
1576     }
1577   }
1578 
1579   return false;
1580 }
1581 #endif
1582 
1583 void HeapShared::init_for_dumping(TRAPS) {
1584   if (HeapShared::can_write()) {
1585     setup_test_class(ArchiveHeapTestClass);
1586     _dumped_interned_strings = new (mtClass)DumpedInternedStrings();
1587     init_subgraph_entry_fields(CHECK);
1588   }
1589 }
1590 
1591 void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
1592                                           bool is_full_module_graph) {
1593   _num_total_subgraph_recordings = 0;
1594   _num_total_walked_objs = 0;
1595   _num_total_archived_objs = 0;
1596   _num_total_recorded_klasses = 0;
1597   _num_total_verifications = 0;
1598 
1599   // For each class X that has one or more archived fields:
1600   // [1] Dump the subgraph of each archived field
1601   // [2] Create a list of all the class of the objects that can be reached
1602   //     by any of these static fields.
1603   //     At runtime, these classes are initialized before X's archived fields
1604   //     are restored by HeapShared::initialize_from_archived_subgraph().
1605   int i;
1606   for (int i = 0; fields[i].valid(); ) {
1607     ArchivableStaticFieldInfo* info = &fields[i];
1608     const char* klass_name = info->klass_name;
1609     start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
1610 
1611     // If you have specified consecutive fields of the same klass in
1612     // fields[], these will be archived in the same
1613     // {start_recording_subgraph ... done_recording_subgraph} pass to
1614     // save time.
1615     for (; fields[i].valid(); i++) {
1616       ArchivableStaticFieldInfo* f = &fields[i];
1617       if (f->klass_name != klass_name) {
1618         break;
1619       }
1620 
1621       archive_reachable_objects_from_static_field(f->klass, f->klass_name,
1622                                                   f->offset, f->field_name);
1623     }
1624     done_recording_subgraph(info->klass, klass_name);
1625   }
1626 
1627   log_info(cds, heap)("Archived subgraph records = %d",
1628                       _num_total_subgraph_recordings);
1629   log_info(cds, heap)("  Walked %d objects", _num_total_walked_objs);
1630   log_info(cds, heap)("  Archived %d objects", _num_total_archived_objs);
1631   log_info(cds, heap)("  Recorded %d klasses", _num_total_recorded_klasses);
1632 
1633 #ifndef PRODUCT
1634   for (int i = 0; fields[i].valid(); i++) {
1635     ArchivableStaticFieldInfo* f = &fields[i];
1636     verify_subgraph_from_static_field(f->klass, f->offset);
1637   }
1638   log_info(cds, heap)("  Verified %d references", _num_total_verifications);
1639 #endif
1640 }
1641 
1642 // Not all the strings in the global StringTable are dumped into the archive, because
1643 // some of those strings may be only referenced by classes that are excluded from
1644 // the archive. We need to explicitly mark the strings that are:
1645 //   [1] used by classes that WILL be archived;
1646 //   [2] included in the SharedArchiveConfigFile.
1647 void HeapShared::add_to_dumped_interned_strings(oop string) {
1648   assert_at_safepoint(); // DumpedInternedStrings uses raw oops
1649   assert(!ArchiveHeapWriter::is_string_too_large_to_archive(string), "must be");
1650   bool created;
1651   _dumped_interned_strings->put_if_absent(string, true, &created);
1652 }
1653 
1654 #ifndef PRODUCT
1655 // At dump-time, find the location of all the non-null oop pointers in an archived heap
1656 // region. This way we can quickly relocate all the pointers without using
1657 // BasicOopIterateClosure at runtime.
1658 class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
1659   void* _start;
1660   BitMap *_oopmap;
1661   int _num_total_oops;
1662   int _num_null_oops;
1663  public:
1664   FindEmbeddedNonNullPointers(void* start, BitMap* oopmap)
1665     : _start(start), _oopmap(oopmap), _num_total_oops(0),  _num_null_oops(0) {}
1666 
1667   virtual void do_oop(narrowOop* p) {
1668     assert(UseCompressedOops, "sanity");
1669     _num_total_oops ++;
1670     narrowOop v = *p;
1671     if (!CompressedOops::is_null(v)) {
1672       // Note: HeapShared::to_requested_address() is not necessary because
1673       // the heap always starts at a deterministic address with UseCompressedOops==true.
1674       size_t idx = p - (narrowOop*)_start;
1675       _oopmap->set_bit(idx);
1676     } else {
1677       _num_null_oops ++;
1678     }
1679   }
1680   virtual void do_oop(oop* p) {
1681     assert(!UseCompressedOops, "sanity");
1682     _num_total_oops ++;
1683     if ((*p) != nullptr) {
1684       size_t idx = p - (oop*)_start;
1685       _oopmap->set_bit(idx);
1686     } else {
1687       _num_null_oops ++;
1688     }
1689   }
1690   int num_total_oops() const { return _num_total_oops; }
1691   int num_null_oops()  const { return _num_null_oops; }
1692 };
1693 #endif
1694 
1695 address HeapShared::to_requested_address(address dumptime_addr) {
1696   assert(DumpSharedSpaces, "static dump time only");
1697   if (dumptime_addr == nullptr || UseCompressedOops) {
1698     return dumptime_addr;
1699   }
1700 
1701   // With UseCompressedOops==false, actual_base is selected by the OS so
1702   // it's different across -Xshare:dump runs.
1703   address actual_base = (address)G1CollectedHeap::heap()->reserved().start();
1704   address actual_end  = (address)G1CollectedHeap::heap()->reserved().end();
1705   assert(actual_base <= dumptime_addr && dumptime_addr <= actual_end, "must be an address in the heap");
1706 
1707   // We always write the objects as if the heap started at this address. This
1708   // makes the heap content deterministic.
1709   //
1710   // Note that at runtime, the heap address is also selected by the OS, so
1711   // the archive heap will not be mapped at 0x10000000. Instead, we will call
1712   // HeapShared::patch_embedded_pointers() to relocate the heap contents
1713   // accordingly.
1714   const address REQUESTED_BASE = (address)0x10000000;
1715   intx delta = REQUESTED_BASE - actual_base;
1716 
1717   address requested_addr = dumptime_addr + delta;
1718   assert(REQUESTED_BASE != 0 && requested_addr != nullptr, "sanity");
1719   return requested_addr;
1720 }
1721 
1722 #ifndef PRODUCT
1723 ResourceBitMap HeapShared::calculate_oopmap(MemRegion region) {
1724   size_t num_bits = region.byte_size() / (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
1725   ResourceBitMap oopmap(num_bits);
1726 
1727   HeapWord* p   = region.start();
1728   HeapWord* end = region.end();
1729   FindEmbeddedNonNullPointers finder((void*)p, &oopmap);
1730 
1731   int num_objs = 0;
1732   while (p < end) {
1733     oop o = cast_to_oop(p);
1734     o->oop_iterate(&finder);
1735     p += o->size();
1736     ++ num_objs;
1737   }
1738 
1739   log_info(cds, heap)("calculate_oopmap: objects = %6d, oop fields = %7d (nulls = %7d)",
1740                       num_objs, finder.num_total_oops(), finder.num_null_oops());
1741   return oopmap;
1742 }
1743 
1744 #endif // !PRODUCT
1745 
1746 void HeapShared::count_allocation(size_t size) {
1747   _total_obj_count ++;
1748   _total_obj_size += size;
1749   for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
1750     if (size <= (size_t(1) << i)) {
1751       _alloc_count[i] ++;
1752       _alloc_size[i] += size;
1753       return;
1754     }
1755   }
1756 }
1757 
1758 static double avg_size(size_t size, size_t count) {
1759   double avg = 0;
1760   if (count > 0) {
1761     avg = double(size * HeapWordSize) / double(count);
1762   }
1763   return avg;
1764 }
1765 
1766 void HeapShared::print_stats() {
1767   size_t huge_count = _total_obj_count;
1768   size_t huge_size = _total_obj_size;
1769 
1770   for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
1771     size_t byte_size_limit = (size_t(1) << i) * HeapWordSize;
1772     size_t count = _alloc_count[i];
1773     size_t size = _alloc_size[i];
1774     log_info(cds, heap)(SIZE_FORMAT_W(8) " objects are <= " SIZE_FORMAT_W(-6)
1775                         " bytes (total " SIZE_FORMAT_W(8) " bytes, avg %8.1f bytes)",
1776                         count, byte_size_limit, size * HeapWordSize, avg_size(size, count));
1777     huge_count -= count;
1778     huge_size -= size;
1779   }
1780 
1781   log_info(cds, heap)(SIZE_FORMAT_W(8) " huge  objects               (total "  SIZE_FORMAT_W(8) " bytes"
1782                       ", avg %8.1f bytes)",
1783                       huge_count, huge_size * HeapWordSize,
1784                       avg_size(huge_size, huge_count));
1785   log_info(cds, heap)(SIZE_FORMAT_W(8) " total objects               (total "  SIZE_FORMAT_W(8) " bytes"
1786                       ", avg %8.1f bytes)",
1787                       _total_obj_count, _total_obj_size * HeapWordSize,
1788                       avg_size(_total_obj_size, _total_obj_count));
1789 }
1790 
1791 #endif // INCLUDE_CDS_JAVA_HEAP