1 /*
   2  * Copyright (c) 2018, 2024, 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/cdsConfig.hpp"
  31 #include "cds/cdsEnumKlass.hpp"
  32 #include "cds/cdsHeapVerifier.hpp"
  33 #include "cds/heapShared.hpp"
  34 #include "cds/metaspaceShared.hpp"
  35 #include "classfile/classLoaderData.hpp"
  36 #include "classfile/javaClasses.inline.hpp"
  37 #include "classfile/modules.hpp"
  38 #include "classfile/stringTable.hpp"
  39 #include "classfile/symbolTable.hpp"
  40 #include "classfile/systemDictionary.hpp"
  41 #include "classfile/systemDictionaryShared.hpp"
  42 #include "classfile/vmClasses.hpp"
  43 #include "classfile/vmSymbols.hpp"
  44 #include "gc/shared/collectedHeap.hpp"
  45 #include "gc/shared/gcLocker.hpp"
  46 #include "gc/shared/gcVMOperations.hpp"
  47 #include "logging/log.hpp"
  48 #include "logging/logStream.hpp"
  49 #include "memory/iterator.inline.hpp"
  50 #include "memory/resourceArea.hpp"
  51 #include "memory/universe.hpp"
  52 #include "oops/compressedOops.inline.hpp"
  53 #include "oops/fieldStreams.inline.hpp"
  54 #include "oops/objArrayOop.inline.hpp"
  55 #include "oops/oop.inline.hpp"
  56 #include "oops/typeArrayOop.inline.hpp"
  57 #include "prims/jvmtiExport.hpp"
  58 #include "runtime/fieldDescriptor.inline.hpp"
  59 #include "runtime/init.hpp"
  60 #include "runtime/javaCalls.hpp"
  61 #include "runtime/mutexLocker.hpp"
  62 #include "runtime/safepointVerifiers.hpp"
  63 #include "utilities/bitMap.inline.hpp"
  64 #include "utilities/copy.hpp"
  65 #if INCLUDE_G1GC
  66 #include "gc/g1/g1CollectedHeap.hpp"
  67 #endif
  68 
  69 #if INCLUDE_CDS_JAVA_HEAP
  70 
  71 struct ArchivableStaticFieldInfo {
  72   const char* klass_name;
  73   const char* field_name;
  74   InstanceKlass* klass;
  75   int offset;
  76   BasicType type;
  77 
  78   ArchivableStaticFieldInfo(const char* k, const char* f)
  79   : klass_name(k), field_name(f), klass(nullptr), offset(0), type(T_ILLEGAL) {}
  80 
  81   bool valid() {
  82     return klass_name != nullptr;
  83   }
  84 };
  85 
  86 bool HeapShared::_disable_writing = false;
  87 DumpedInternedStrings *HeapShared::_dumped_interned_strings = nullptr;
  88 
  89 size_t HeapShared::_alloc_count[HeapShared::ALLOC_STAT_SLOTS];
  90 size_t HeapShared::_alloc_size[HeapShared::ALLOC_STAT_SLOTS];
  91 size_t HeapShared::_total_obj_count;
  92 size_t HeapShared::_total_obj_size;
  93 
  94 #ifndef PRODUCT
  95 #define ARCHIVE_TEST_FIELD_NAME "archivedObjects"
  96 static Array<char>* _archived_ArchiveHeapTestClass = nullptr;
  97 static const char* _test_class_name = nullptr;
  98 static const Klass* _test_class = nullptr;
  99 static const ArchivedKlassSubGraphInfoRecord* _test_class_record = nullptr;
 100 #endif
 101 
 102 
 103 //
 104 // If you add new entries to the following tables, you should know what you're doing!
 105 //
 106 
 107 static ArchivableStaticFieldInfo archive_subgraph_entry_fields[] = {
 108   {"java/lang/Integer$IntegerCache",              "archivedCache"},
 109   {"java/lang/Long$LongCache",                    "archivedCache"},
 110   {"java/lang/Byte$ByteCache",                    "archivedCache"},
 111   {"java/lang/Short$ShortCache",                  "archivedCache"},
 112   {"java/lang/Character$CharacterCache",          "archivedCache"},
 113   {"java/util/jar/Attributes$Name",               "KNOWN_NAMES"},
 114   {"sun/util/locale/BaseLocale",                  "constantBaseLocales"},
 115   {"jdk/internal/module/ArchivedModuleGraph",     "archivedModuleGraph"},
 116   {"java/util/ImmutableCollections",              "archivedObjects"},
 117   {"java/lang/ModuleLayer",                       "EMPTY_LAYER"},
 118   {"java/lang/module/Configuration",              "EMPTY_CONFIGURATION"},
 119   {"jdk/internal/math/FDBigInteger",              "archivedCaches"},
 120 #ifndef PRODUCT
 121   {nullptr, nullptr}, // Extra slot for -XX:ArchiveHeapTestClass
 122 #endif
 123   {nullptr, nullptr},
 124 };
 125 
 126 // full module graph
 127 static ArchivableStaticFieldInfo fmg_archive_subgraph_entry_fields[] = {
 128   {"jdk/internal/loader/ArchivedClassLoaders",    "archivedClassLoaders"},
 129   {ARCHIVED_BOOT_LAYER_CLASS,                     ARCHIVED_BOOT_LAYER_FIELD},
 130   {"java/lang/Module$ArchivedData",               "archivedData"},
 131   {nullptr, nullptr},
 132 };
 133 
 134 KlassSubGraphInfo* HeapShared::_default_subgraph_info;
 135 GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = nullptr;
 136 OopHandle HeapShared::_roots;
 137 OopHandle HeapShared::_scratch_basic_type_mirrors[T_VOID+1];
 138 MetaspaceObjToOopHandleTable* HeapShared::_scratch_java_mirror_table = nullptr;
 139 MetaspaceObjToOopHandleTable* HeapShared::_scratch_references_table = nullptr;
 140 
 141 static bool is_subgraph_root_class_of(ArchivableStaticFieldInfo fields[], InstanceKlass* ik) {
 142   for (int i = 0; fields[i].valid(); i++) {
 143     if (fields[i].klass == ik) {
 144       return true;
 145     }
 146   }
 147   return false;
 148 }
 149 
 150 bool HeapShared::is_subgraph_root_class(InstanceKlass* ik) {
 151   return is_subgraph_root_class_of(archive_subgraph_entry_fields, ik) ||
 152          is_subgraph_root_class_of(fmg_archive_subgraph_entry_fields, ik);
 153 }
 154 
 155 unsigned HeapShared::oop_hash(oop const& p) {
 156   // Do not call p->identity_hash() as that will update the
 157   // object header.
 158   return primitive_hash(cast_from_oop<intptr_t>(p));
 159 }
 160 
 161 static void reset_states(oop obj, TRAPS) {
 162   Handle h_obj(THREAD, obj);
 163   InstanceKlass* klass = InstanceKlass::cast(obj->klass());
 164   TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
 165   Symbol* method_sig = vmSymbols::void_method_signature();
 166 
 167   while (klass != nullptr) {
 168     Method* method = klass->find_method(method_name, method_sig);
 169     if (method != nullptr) {
 170       assert(method->is_private(), "must be");
 171       if (log_is_enabled(Debug, cds)) {
 172         ResourceMark rm(THREAD);
 173         log_debug(cds)("  calling %s", method->name_and_sig_as_C_string());
 174       }
 175       JavaValue result(T_VOID);
 176       JavaCalls::call_special(&result, h_obj, klass,
 177                               method_name, method_sig, CHECK);
 178     }
 179     klass = klass->java_super();
 180   }
 181 }
 182 
 183 void HeapShared::reset_archived_object_states(TRAPS) {
 184   assert(CDSConfig::is_dumping_heap(), "dump-time only");
 185   log_debug(cds)("Resetting platform loader");
 186   reset_states(SystemDictionary::java_platform_loader(), CHECK);
 187   log_debug(cds)("Resetting system loader");
 188   reset_states(SystemDictionary::java_system_loader(), CHECK);
 189 
 190   // Clean up jdk.internal.loader.ClassLoaders::bootLoader(), which is not
 191   // directly used for class loading, but rather is used by the core library
 192   // to keep track of resources, etc, loaded by the null class loader.
 193   //
 194   // Note, this object is non-null, and is not the same as
 195   // ClassLoaderData::the_null_class_loader_data()->class_loader(),
 196   // which is null.
 197   log_debug(cds)("Resetting boot loader");
 198   JavaValue result(T_OBJECT);
 199   JavaCalls::call_static(&result,
 200                          vmClasses::jdk_internal_loader_ClassLoaders_klass(),
 201                          vmSymbols::bootLoader_name(),
 202                          vmSymbols::void_BuiltinClassLoader_signature(),
 203                          CHECK);
 204   Handle boot_loader(THREAD, result.get_oop());
 205   reset_states(boot_loader(), CHECK);
 206 }
 207 
 208 HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = nullptr;
 209 
 210 bool HeapShared::has_been_archived(oop obj) {
 211   assert(CDSConfig::is_dumping_heap(), "dump-time only");
 212   return archived_object_cache()->get(obj) != nullptr;
 213 }
 214 
 215 int HeapShared::append_root(oop obj) {
 216   assert(CDSConfig::is_dumping_heap(), "dump-time only");
 217 
 218   // No GC should happen since we aren't scanning _pending_roots.
 219   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 220 
 221   if (_pending_roots == nullptr) {
 222     _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
 223   }
 224 
 225   return _pending_roots->append(obj);
 226 }
 227 
 228 objArrayOop HeapShared::roots() {
 229   if (CDSConfig::is_dumping_heap()) {
 230     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 231     if (!HeapShared::can_write()) {
 232       return nullptr;
 233     }
 234   } else {
 235     assert(CDSConfig::is_using_archive(), "must be");
 236   }
 237 
 238   objArrayOop roots = (objArrayOop)_roots.resolve();
 239   assert(roots != nullptr, "should have been initialized");
 240   return roots;
 241 }
 242 
 243 // Returns an objArray that contains all the roots of the archived objects
 244 oop HeapShared::get_root(int index, bool clear) {
 245   assert(index >= 0, "sanity");
 246   assert(!CDSConfig::is_dumping_heap() && CDSConfig::is_using_archive(), "runtime only");
 247   assert(!_roots.is_empty(), "must have loaded shared heap");
 248   oop result = roots()->obj_at(index);
 249   if (clear) {
 250     clear_root(index);
 251   }
 252   return result;
 253 }
 254 
 255 void HeapShared::clear_root(int index) {
 256   assert(index >= 0, "sanity");
 257   assert(CDSConfig::is_using_archive(), "must be");
 258   if (ArchiveHeapLoader::is_in_use()) {
 259     if (log_is_enabled(Debug, cds, heap)) {
 260       oop old = roots()->obj_at(index);
 261       log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
 262     }
 263     roots()->obj_at_put(index, nullptr);
 264   }
 265 }
 266 
 267 bool HeapShared::archive_object(oop obj) {
 268   assert(CDSConfig::is_dumping_heap(), "dump-time only");
 269 
 270   assert(!obj->is_stackChunk(), "do not archive stack chunks");
 271   if (has_been_archived(obj)) {
 272     return true;
 273   }
 274 
 275   if (ArchiveHeapWriter::is_too_large_to_archive(obj->size())) {
 276     log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
 277                          p2i(obj), obj->size());
 278     return false;
 279   } else {
 280     count_allocation(obj->size());
 281     ArchiveHeapWriter::add_source_obj(obj);
 282     CachedOopInfo info = make_cached_oop_info(obj);
 283     archived_object_cache()->put_when_absent(obj, info);
 284     archived_object_cache()->maybe_grow();
 285     mark_native_pointers(obj);
 286 
 287     if (log_is_enabled(Debug, cds, heap)) {
 288       ResourceMark rm;
 289       log_debug(cds, heap)("Archived heap object " PTR_FORMAT " : %s",
 290                            p2i(obj), obj->klass()->external_name());
 291     }
 292 
 293     if (java_lang_Module::is_instance(obj) && Modules::check_archived_module_oop(obj)) {
 294       Modules::update_oops_in_archived_module(obj, append_root(obj));
 295     }
 296 
 297     return true;
 298   }
 299 }
 300 
 301 class MetaspaceObjToOopHandleTable: public ResourceHashtable<MetaspaceObj*, OopHandle,
 302     36137, // prime number
 303     AnyObj::C_HEAP,
 304     mtClassShared> {
 305 public:
 306   oop get_oop(MetaspaceObj* ptr) {
 307     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 308     OopHandle* handle = get(ptr);
 309     if (handle != nullptr) {
 310       return handle->resolve();
 311     } else {
 312       return nullptr;
 313     }
 314   }
 315   void set_oop(MetaspaceObj* ptr, oop o) {
 316     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 317     OopHandle handle(Universe::vm_global(), o);
 318     bool is_new = put(ptr, handle);
 319     assert(is_new, "cannot set twice");
 320   }
 321   void remove_oop(MetaspaceObj* ptr) {
 322     MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
 323     OopHandle* handle = get(ptr);
 324     if (handle != nullptr) {
 325       handle->release(Universe::vm_global());
 326       remove(ptr);
 327     }
 328   }
 329 };
 330 
 331 void HeapShared::add_scratch_resolved_references(ConstantPool* src, objArrayOop dest) {
 332   _scratch_references_table->set_oop(src, dest);
 333 }
 334 
 335 objArrayOop HeapShared::scratch_resolved_references(ConstantPool* src) {
 336   return (objArrayOop)_scratch_references_table->get_oop(src);
 337 }
 338 
 339 void HeapShared::init_scratch_objects(TRAPS) {
 340   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
 341     BasicType bt = (BasicType)i;
 342     if (!is_reference_type(bt)) {
 343       oop m = java_lang_Class::create_basic_type_mirror(type2name(bt), bt, CHECK);
 344       _scratch_basic_type_mirrors[i] = OopHandle(Universe::vm_global(), m);
 345     }
 346   }
 347   _scratch_java_mirror_table = new (mtClass)MetaspaceObjToOopHandleTable();
 348   _scratch_references_table = new (mtClass)MetaspaceObjToOopHandleTable();
 349 }
 350 
 351 oop HeapShared::scratch_java_mirror(BasicType t) {
 352   assert((uint)t < T_VOID+1, "range check");
 353   assert(!is_reference_type(t), "sanity");
 354   return _scratch_basic_type_mirrors[t].resolve();
 355 }
 356 
 357 oop HeapShared::scratch_java_mirror(Klass* k) {
 358   return _scratch_java_mirror_table->get_oop(k);
 359 }
 360 
 361 void HeapShared::set_scratch_java_mirror(Klass* k, oop mirror) {
 362   _scratch_java_mirror_table->set_oop(k, mirror);
 363 }
 364 
 365 void HeapShared::remove_scratch_objects(Klass* k) {
 366   _scratch_java_mirror_table->remove_oop(k);
 367   if (k->is_instance_klass()) {
 368     _scratch_references_table->remove(InstanceKlass::cast(k)->constants());
 369   }
 370 }
 371 
 372 void HeapShared::archive_java_mirrors() {
 373   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
 374     BasicType bt = (BasicType)i;
 375     if (!is_reference_type(bt)) {
 376       oop m = _scratch_basic_type_mirrors[i].resolve();
 377       assert(m != nullptr, "sanity");
 378       bool success = archive_reachable_objects_from(1, _default_subgraph_info, m);
 379       assert(success, "sanity");
 380 
 381       log_trace(cds, heap, mirror)(
 382         "Archived %s mirror object from " PTR_FORMAT,
 383         type2name(bt), p2i(m));
 384 
 385       Universe::set_archived_basic_type_mirror_index(bt, append_root(m));
 386     }
 387   }
 388 
 389   GrowableArray<Klass*>* klasses = ArchiveBuilder::current()->klasses();
 390   assert(klasses != nullptr, "sanity");
 391   for (int i = 0; i < klasses->length(); i++) {
 392     Klass* orig_k = klasses->at(i);
 393     oop m = scratch_java_mirror(orig_k);
 394     if (m != nullptr) {
 395       Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
 396       bool success = archive_reachable_objects_from(1, _default_subgraph_info, m);
 397       guarantee(success, "scratch mirrors must point to only archivable objects");
 398       buffered_k->set_archived_java_mirror(append_root(m));
 399       ResourceMark rm;
 400       log_trace(cds, heap, mirror)(
 401         "Archived %s mirror object from " PTR_FORMAT,
 402         buffered_k->external_name(), p2i(m));
 403 
 404       // archive the resolved_referenes array
 405       if (buffered_k->is_instance_klass()) {
 406         InstanceKlass* ik = InstanceKlass::cast(buffered_k);
 407         oop rr = ik->constants()->prepare_resolved_references_for_archiving();
 408         if (rr != nullptr && !ArchiveHeapWriter::is_too_large_to_archive(rr)) {
 409           bool success = HeapShared::archive_reachable_objects_from(1, _default_subgraph_info, rr);
 410           assert(success, "must be");
 411           int root_index = append_root(rr);
 412           ik->constants()->cache()->set_archived_references(root_index);
 413         }
 414       }
 415     }
 416   }
 417 }
 418 
 419 void HeapShared::archive_strings() {
 420   oop shared_strings_array = StringTable::init_shared_table(_dumped_interned_strings);
 421   bool success = archive_reachable_objects_from(1, _default_subgraph_info, shared_strings_array);
 422   // We must succeed because:
 423   // - _dumped_interned_strings do not contain any large strings.
 424   // - StringTable::init_shared_table() doesn't create any large arrays.
 425   assert(success, "shared strings array must not point to arrays or strings that are too large to archive");
 426   StringTable::set_shared_strings_array_index(append_root(shared_strings_array));
 427 }
 428 
 429 int HeapShared::archive_exception_instance(oop exception) {
 430   bool success = archive_reachable_objects_from(1, _default_subgraph_info, exception);
 431   assert(success, "sanity");
 432   return append_root(exception);
 433 }
 434 
 435 void HeapShared::mark_native_pointers(oop orig_obj) {
 436   if (java_lang_Class::is_instance(orig_obj)) {
 437     ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::klass_offset());
 438     ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::array_klass_offset());
 439   }
 440 }
 441 
 442 void HeapShared::get_pointer_info(oop src_obj, bool& has_oop_pointers, bool& has_native_pointers) {
 443   CachedOopInfo* info = archived_object_cache()->get(src_obj);
 444   assert(info != nullptr, "must be");
 445   has_oop_pointers = info->has_oop_pointers();
 446   has_native_pointers = info->has_native_pointers();
 447 }
 448 
 449 void HeapShared::set_has_native_pointers(oop src_obj) {
 450   CachedOopInfo* info = archived_object_cache()->get(src_obj);
 451   assert(info != nullptr, "must be");
 452   info->set_has_native_pointers();
 453 }
 454 
 455 void HeapShared::archive_objects(ArchiveHeapInfo *heap_info) {
 456   {
 457     NoSafepointVerifier nsv;
 458 
 459     _default_subgraph_info = init_subgraph_info(vmClasses::Object_klass(), false);
 460 
 461     // Cache for recording where the archived objects are copied to
 462     create_archived_object_cache();
 463 
 464     log_info(cds)("Heap range = [" PTR_FORMAT " - "  PTR_FORMAT "]",
 465                    UseCompressedOops ? p2i(CompressedOops::begin()) :
 466                                        p2i((address)G1CollectedHeap::heap()->reserved().start()),
 467                    UseCompressedOops ? p2i(CompressedOops::end()) :
 468                                        p2i((address)G1CollectedHeap::heap()->reserved().end()));
 469     copy_objects();
 470 
 471     CDSHeapVerifier::verify();
 472     check_default_subgraph_classes();
 473   }
 474 
 475   ArchiveHeapWriter::write(_pending_roots, heap_info);
 476 }
 477 
 478 void HeapShared::copy_interned_strings() {
 479   init_seen_objects_table();
 480 
 481   auto copier = [&] (oop s, bool value_ignored) {
 482     assert(s != nullptr, "sanity");
 483     assert(!ArchiveHeapWriter::is_string_too_large_to_archive(s), "large strings must have been filtered");
 484     bool success = archive_reachable_objects_from(1, _default_subgraph_info, s);
 485     assert(success, "must be");
 486     // Prevent string deduplication from changing the value field to
 487     // something not in the archive.
 488     java_lang_String::set_deduplication_forbidden(s);
 489   };
 490   _dumped_interned_strings->iterate_all(copier);
 491 
 492   delete_seen_objects_table();
 493 }
 494 
 495 void HeapShared::copy_special_objects() {
 496   // Archive special objects that do not belong to any subgraphs
 497   init_seen_objects_table();
 498   archive_java_mirrors();
 499   archive_strings();
 500   Universe::archive_exception_instances();
 501   delete_seen_objects_table();
 502 }
 503 
 504 void HeapShared::copy_objects() {
 505   assert(HeapShared::can_write(), "must be");
 506 
 507   copy_interned_strings();
 508   copy_special_objects();
 509 
 510   archive_object_subgraphs(archive_subgraph_entry_fields,
 511                            false /* is_full_module_graph */);
 512 
 513   if (CDSConfig::is_dumping_full_module_graph()) {
 514     archive_object_subgraphs(fmg_archive_subgraph_entry_fields,
 515                              true /* is_full_module_graph */);
 516     Modules::verify_archived_modules();
 517   }
 518 }
 519 
 520 //
 521 // Subgraph archiving support
 522 //
 523 HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = nullptr;
 524 HeapShared::RunTimeKlassSubGraphInfoTable   HeapShared::_run_time_subgraph_info_table;
 525 
 526 // Get the subgraph_info for Klass k. A new subgraph_info is created if
 527 // there is no existing one for k. The subgraph_info records the "buffered"
 528 // address of the class.
 529 KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
 530   assert(CDSConfig::is_dumping_heap(), "dump time only");
 531   bool created;
 532   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(k);
 533   KlassSubGraphInfo* info =
 534     _dump_time_subgraph_info_table->put_if_absent(k, KlassSubGraphInfo(buffered_k, is_full_module_graph),
 535                                                   &created);
 536   assert(created, "must not initialize twice");
 537   return info;
 538 }
 539 
 540 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
 541   assert(CDSConfig::is_dumping_heap(), "dump time only");
 542   KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
 543   assert(info != nullptr, "must have been initialized");
 544   return info;
 545 }
 546 
 547 // Add an entry field to the current KlassSubGraphInfo.
 548 void KlassSubGraphInfo::add_subgraph_entry_field(int static_field_offset, oop v) {
 549   assert(CDSConfig::is_dumping_heap(), "dump time only");
 550   if (_subgraph_entry_fields == nullptr) {
 551     _subgraph_entry_fields =
 552       new (mtClass) GrowableArray<int>(10, mtClass);
 553   }
 554   _subgraph_entry_fields->append(static_field_offset);
 555   _subgraph_entry_fields->append(HeapShared::append_root(v));
 556 }
 557 
 558 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
 559 // Only objects of boot classes can be included in sub-graph.
 560 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
 561   assert(CDSConfig::is_dumping_heap(), "dump time only");
 562   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
 563 
 564   if (_subgraph_object_klasses == nullptr) {
 565     _subgraph_object_klasses =
 566       new (mtClass) GrowableArray<Klass*>(50, mtClass);
 567   }
 568 
 569   assert(ArchiveBuilder::current()->is_in_buffer_space(buffered_k), "must be a shared class");
 570 
 571   if (_k == buffered_k) {
 572     // Don't add the Klass containing the sub-graph to it's own klass
 573     // initialization list.
 574     return;
 575   }
 576 
 577   if (buffered_k->is_instance_klass()) {
 578     assert(InstanceKlass::cast(buffered_k)->is_shared_boot_class(),
 579           "must be boot class");
 580     // vmClasses::xxx_klass() are not updated, need to check
 581     // the original Klass*
 582     if (orig_k == vmClasses::String_klass() ||
 583         orig_k == vmClasses::Object_klass()) {
 584       // Initialized early during VM initialization. No need to be added
 585       // to the sub-graph object class list.
 586       return;
 587     }
 588     check_allowed_klass(InstanceKlass::cast(orig_k));
 589   } else if (buffered_k->is_objArray_klass()) {
 590     Klass* abk = ObjArrayKlass::cast(buffered_k)->bottom_klass();
 591     if (abk->is_instance_klass()) {
 592       assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
 593             "must be boot class");
 594       check_allowed_klass(InstanceKlass::cast(ObjArrayKlass::cast(orig_k)->bottom_klass()));
 595     }
 596     if (buffered_k == Universe::objectArrayKlass()) {
 597       // Initialized early during Universe::genesis. No need to be added
 598       // to the list.
 599       return;
 600     }
 601   } else {
 602     assert(buffered_k->is_typeArray_klass(), "must be");
 603     // Primitive type arrays are created early during Universe::genesis.
 604     return;
 605   }
 606 
 607   if (log_is_enabled(Debug, cds, heap)) {
 608     if (!_subgraph_object_klasses->contains(buffered_k)) {
 609       ResourceMark rm;
 610       log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
 611     }
 612   }
 613 
 614   _subgraph_object_klasses->append_if_missing(buffered_k);
 615   _has_non_early_klasses |= is_non_early_klass(orig_k);
 616 }
 617 
 618 void KlassSubGraphInfo::check_allowed_klass(InstanceKlass* ik) {
 619   if (ik->module()->name() == vmSymbols::java_base()) {
 620     assert(ik->package() != nullptr, "classes in java.base cannot be in unnamed package");
 621     return;
 622   }
 623 
 624 #ifndef PRODUCT
 625   if (!ik->module()->is_named() && ik->package() == nullptr) {
 626     // This class is loaded by ArchiveHeapTestClass
 627     return;
 628   }
 629   const char* extra_msg = ", or in an unnamed package of an unnamed module";
 630 #else
 631   const char* extra_msg = "";
 632 #endif
 633 
 634   ResourceMark rm;
 635   log_error(cds, heap)("Class %s not allowed in archive heap. Must be in java.base%s",
 636                        ik->external_name(), extra_msg);
 637   MetaspaceShared::unrecoverable_writing_error();
 638 }
 639 
 640 bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
 641   if (k->is_objArray_klass()) {
 642     k = ObjArrayKlass::cast(k)->bottom_klass();
 643   }
 644   if (k->is_instance_klass()) {
 645     if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
 646       ResourceMark rm;
 647       log_info(cds, heap)("non-early: %s", k->external_name());
 648       return true;
 649     } else {
 650       return false;
 651     }
 652   } else {
 653     return false;
 654   }
 655 }
 656 
 657 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
 658 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
 659   _k = info->klass();
 660   _entry_field_records = nullptr;
 661   _subgraph_object_klasses = nullptr;
 662   _is_full_module_graph = info->is_full_module_graph();
 663 
 664   if (_is_full_module_graph) {
 665     // Consider all classes referenced by the full module graph as early -- we will be
 666     // allocating objects of these classes during JVMTI early phase, so they cannot
 667     // be processed by (non-early) JVMTI ClassFileLoadHook
 668     _has_non_early_klasses = false;
 669   } else {
 670     _has_non_early_klasses = info->has_non_early_klasses();
 671   }
 672 
 673   if (_has_non_early_klasses) {
 674     ResourceMark rm;
 675     log_info(cds, heap)(
 676           "Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
 677           _k->external_name());
 678   }
 679 
 680   // populate the entry fields
 681   GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
 682   if (entry_fields != nullptr) {
 683     int num_entry_fields = entry_fields->length();
 684     assert(num_entry_fields % 2 == 0, "sanity");
 685     _entry_field_records =
 686       ArchiveBuilder::new_ro_array<int>(num_entry_fields);
 687     for (int i = 0 ; i < num_entry_fields; i++) {
 688       _entry_field_records->at_put(i, entry_fields->at(i));
 689     }
 690   }
 691 
 692   // the Klasses of the objects in the sub-graphs
 693   GrowableArray<Klass*>* subgraph_object_klasses = info->subgraph_object_klasses();
 694   if (subgraph_object_klasses != nullptr) {
 695     int num_subgraphs_klasses = subgraph_object_klasses->length();
 696     _subgraph_object_klasses =
 697       ArchiveBuilder::new_ro_array<Klass*>(num_subgraphs_klasses);
 698     for (int i = 0; i < num_subgraphs_klasses; i++) {
 699       Klass* subgraph_k = subgraph_object_klasses->at(i);
 700       if (log_is_enabled(Info, cds, heap)) {
 701         ResourceMark rm;
 702         log_info(cds, heap)(
 703           "Archived object klass %s (%2d) => %s",
 704           _k->external_name(), i, subgraph_k->external_name());
 705       }
 706       _subgraph_object_klasses->at_put(i, subgraph_k);
 707       ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(i));
 708     }
 709   }
 710 
 711   ArchivePtrMarker::mark_pointer(&_k);
 712   ArchivePtrMarker::mark_pointer(&_entry_field_records);
 713   ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
 714 }
 715 
 716 struct CopyKlassSubGraphInfoToArchive : StackObj {
 717   CompactHashtableWriter* _writer;
 718   CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
 719 
 720   bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
 721     if (info.subgraph_object_klasses() != nullptr || info.subgraph_entry_fields() != nullptr) {
 722       ArchivedKlassSubGraphInfoRecord* record =
 723         (ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
 724       record->init(&info);
 725 
 726       Klass* buffered_k = ArchiveBuilder::get_buffered_klass(klass);
 727       unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary((address)buffered_k);
 728       u4 delta = ArchiveBuilder::current()->any_to_offset_u4(record);
 729       _writer->add(hash, delta);
 730     }
 731     return true; // keep on iterating
 732   }
 733 };
 734 
 735 // Build the records of archived subgraph infos, which include:
 736 // - Entry points to all subgraphs from the containing class mirror. The entry
 737 //   points are static fields in the mirror. For each entry point, the field
 738 //   offset, and value are recorded in the sub-graph
 739 //   info. The value is stored back to the corresponding field at runtime.
 740 // - A list of klasses that need to be loaded/initialized before archived
 741 //   java object sub-graph can be accessed at runtime.
 742 void HeapShared::write_subgraph_info_table() {
 743   // Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
 744   DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
 745   CompactHashtableStats stats;
 746 
 747   _run_time_subgraph_info_table.reset();
 748 
 749   CompactHashtableWriter writer(d_table->_count, &stats);
 750   CopyKlassSubGraphInfoToArchive copy(&writer);
 751   d_table->iterate(&copy);
 752   writer.dump(&_run_time_subgraph_info_table, "subgraphs");
 753 
 754 #ifndef PRODUCT
 755   if (ArchiveHeapTestClass != nullptr) {
 756     size_t len = strlen(ArchiveHeapTestClass) + 1;
 757     Array<char>* array = ArchiveBuilder::new_ro_array<char>((int)len);
 758     strncpy(array->adr_at(0), ArchiveHeapTestClass, len);
 759     _archived_ArchiveHeapTestClass = array;
 760   }
 761 #endif
 762   if (log_is_enabled(Info, cds, heap)) {
 763     print_stats();
 764   }
 765 }
 766 
 767 void HeapShared::init_roots(oop roots_oop) {
 768   if (roots_oop != nullptr) {
 769     assert(ArchiveHeapLoader::is_in_use(), "must be");
 770     _roots = OopHandle(Universe::vm_global(), roots_oop);
 771   }
 772 }
 773 
 774 void HeapShared::serialize_tables(SerializeClosure* soc) {
 775 
 776 #ifndef PRODUCT
 777   soc->do_ptr(&_archived_ArchiveHeapTestClass);
 778   if (soc->reading() && _archived_ArchiveHeapTestClass != nullptr) {
 779     _test_class_name = _archived_ArchiveHeapTestClass->adr_at(0);
 780     setup_test_class(_test_class_name);
 781   }
 782 #endif
 783 
 784   _run_time_subgraph_info_table.serialize_header(soc);
 785 }
 786 
 787 static void verify_the_heap(Klass* k, const char* which) {
 788   if (VerifyArchivedFields > 0) {
 789     ResourceMark rm;
 790     log_info(cds, heap)("Verify heap %s initializing static field(s) in %s",
 791                         which, k->external_name());
 792 
 793     VM_Verify verify_op;
 794     VMThread::execute(&verify_op);
 795 
 796     if (VerifyArchivedFields > 1 && is_init_completed()) {
 797       // At this time, the oop->klass() of some archived objects in the heap may not
 798       // have been loaded into the system dictionary yet. Nevertheless, oop->klass() should
 799       // have enough information (object size, oop maps, etc) so that a GC can be safely
 800       // performed.
 801       //
 802       // -XX:VerifyArchivedFields=2 force a GC to happen in such an early stage
 803       // to check for GC safety.
 804       log_info(cds, heap)("Trigger GC %s initializing static field(s) in %s",
 805                           which, k->external_name());
 806       FlagSetting fs1(VerifyBeforeGC, true);
 807       FlagSetting fs2(VerifyDuringGC, true);
 808       FlagSetting fs3(VerifyAfterGC,  true);
 809       Universe::heap()->collect(GCCause::_java_lang_system_gc);
 810     }
 811   }
 812 }
 813 
 814 // Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
 815 // have a valid klass. I.e., oopDesc::klass() must have already been resolved.
 816 //
 817 // Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
 818 // ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
 819 // this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
 820 void HeapShared::resolve_classes(JavaThread* current) {
 821   assert(CDSConfig::is_using_archive(), "runtime only!");
 822   if (!ArchiveHeapLoader::is_in_use()) {
 823     return; // nothing to do
 824   }
 825   resolve_classes_for_subgraphs(current, archive_subgraph_entry_fields);
 826   resolve_classes_for_subgraphs(current, fmg_archive_subgraph_entry_fields);
 827 }
 828 
 829 void HeapShared::resolve_classes_for_subgraphs(JavaThread* current, ArchivableStaticFieldInfo fields[]) {
 830   for (int i = 0; fields[i].valid(); i++) {
 831     ArchivableStaticFieldInfo* info = &fields[i];
 832     TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
 833     InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
 834     assert(k != nullptr && k->is_shared_boot_class(), "sanity");
 835     resolve_classes_for_subgraph_of(current, k);
 836   }
 837 }
 838 
 839 void HeapShared::resolve_classes_for_subgraph_of(JavaThread* current, Klass* k) {
 840   JavaThread* THREAD = current;
 841   ExceptionMark em(THREAD);
 842   const ArchivedKlassSubGraphInfoRecord* record =
 843    resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
 844   if (HAS_PENDING_EXCEPTION) {
 845    CLEAR_PENDING_EXCEPTION;
 846   }
 847   if (record == nullptr) {
 848    clear_archived_roots_of(k);
 849   }
 850 }
 851 
 852 void HeapShared::initialize_from_archived_subgraph(JavaThread* current, Klass* k) {
 853   JavaThread* THREAD = current;
 854   if (!ArchiveHeapLoader::is_in_use()) {
 855     return; // nothing to do
 856   }
 857 
 858   ExceptionMark em(THREAD);
 859   const ArchivedKlassSubGraphInfoRecord* record =
 860     resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
 861 
 862   if (HAS_PENDING_EXCEPTION) {
 863     CLEAR_PENDING_EXCEPTION;
 864     // None of the field value will be set if there was an exception when initializing the classes.
 865     // The java code will not see any of the archived objects in the
 866     // subgraphs referenced from k in this case.
 867     return;
 868   }
 869 
 870   if (record != nullptr) {
 871     init_archived_fields_for(k, record);
 872   }
 873 }
 874 
 875 const ArchivedKlassSubGraphInfoRecord*
 876 HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
 877   assert(!CDSConfig::is_dumping_heap(), "Should not be called when dumping heap");
 878 
 879   if (!k->is_shared()) {
 880     return nullptr;
 881   }
 882   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
 883   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 884 
 885 #ifndef PRODUCT
 886   if (_test_class_name != nullptr && k->name()->equals(_test_class_name) && record != nullptr) {
 887     _test_class = k;
 888     _test_class_record = record;
 889   }
 890 #endif
 891 
 892   // Initialize from archived data. Currently this is done only
 893   // during VM initialization time. No lock is needed.
 894   if (record == nullptr) {
 895     if (log_is_enabled(Info, cds, heap)) {
 896       ResourceMark rm(THREAD);
 897       log_info(cds, heap)("subgraph %s is not recorded",
 898                           k->external_name());
 899     }
 900     return nullptr;
 901   } else {
 902     if (record->is_full_module_graph() && !CDSConfig::is_using_full_module_graph()) {
 903       if (log_is_enabled(Info, cds, heap)) {
 904         ResourceMark rm(THREAD);
 905         log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
 906                             k->external_name());
 907       }
 908       return nullptr;
 909     }
 910 
 911     if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
 912       if (log_is_enabled(Info, cds, heap)) {
 913         ResourceMark rm(THREAD);
 914         log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
 915                             k->external_name());
 916       }
 917       return nullptr;
 918     }
 919 
 920     if (log_is_enabled(Info, cds, heap)) {
 921       ResourceMark rm;
 922       log_info(cds, heap)("%s subgraph %s ", do_init ? "init" : "resolve", k->external_name());
 923     }
 924 
 925     resolve_or_init(k, do_init, CHECK_NULL);
 926 
 927     // Load/link/initialize the klasses of the objects in the subgraph.
 928     // nullptr class loader is used.
 929     Array<Klass*>* klasses = record->subgraph_object_klasses();
 930     if (klasses != nullptr) {
 931       for (int i = 0; i < klasses->length(); i++) {
 932         Klass* klass = klasses->at(i);
 933         if (!klass->is_shared()) {
 934           return nullptr;
 935         }
 936         resolve_or_init(klass, do_init, CHECK_NULL);
 937       }
 938     }
 939   }
 940 
 941   return record;
 942 }
 943 
 944 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
 945   if (!do_init) {
 946     if (k->class_loader_data() == nullptr) {
 947       Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
 948       assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
 949     }
 950   } else {
 951     assert(k->class_loader_data() != nullptr, "must have been resolved by HeapShared::resolve_classes");
 952     if (k->is_instance_klass()) {
 953       InstanceKlass* ik = InstanceKlass::cast(k);
 954       ik->initialize(CHECK);
 955     } else if (k->is_objArray_klass()) {
 956       ObjArrayKlass* oak = ObjArrayKlass::cast(k);
 957       oak->initialize(CHECK);
 958     }
 959   }
 960 }
 961 
 962 void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record) {
 963   verify_the_heap(k, "before");
 964 
 965   // Load the subgraph entry fields from the record and store them back to
 966   // the corresponding fields within the mirror.
 967   oop m = k->java_mirror();
 968   Array<int>* entry_field_records = record->entry_field_records();
 969   if (entry_field_records != nullptr) {
 970     int efr_len = entry_field_records->length();
 971     assert(efr_len % 2 == 0, "sanity");
 972     for (int i = 0; i < efr_len; i += 2) {
 973       int field_offset = entry_field_records->at(i);
 974       int root_index = entry_field_records->at(i+1);
 975       oop v = get_root(root_index, /*clear=*/true);
 976       m->obj_field_put(field_offset, v);
 977       log_debug(cds, heap)("  " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
 978     }
 979 
 980     // Done. Java code can see the archived sub-graphs referenced from k's
 981     // mirror after this point.
 982     if (log_is_enabled(Info, cds, heap)) {
 983       ResourceMark rm;
 984       log_info(cds, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s",
 985                           k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "");
 986     }
 987   }
 988 
 989   verify_the_heap(k, "after ");
 990 }
 991 
 992 void HeapShared::clear_archived_roots_of(Klass* k) {
 993   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
 994   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 995   if (record != nullptr) {
 996     Array<int>* entry_field_records = record->entry_field_records();
 997     if (entry_field_records != nullptr) {
 998       int efr_len = entry_field_records->length();
 999       assert(efr_len % 2 == 0, "sanity");
1000       for (int i = 0; i < efr_len; i += 2) {
1001         int root_index = entry_field_records->at(i+1);
1002         clear_root(root_index);
1003       }
1004     }
1005   }
1006 }
1007 
1008 class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
1009   int _level;
1010   bool _record_klasses_only;
1011   KlassSubGraphInfo* _subgraph_info;
1012   oop _referencing_obj;
1013 
1014   // The following are for maintaining a stack for determining
1015   // CachedOopInfo::_referrer
1016   static WalkOopAndArchiveClosure* _current;
1017   WalkOopAndArchiveClosure* _last;
1018  public:
1019   WalkOopAndArchiveClosure(int level,
1020                            bool record_klasses_only,
1021                            KlassSubGraphInfo* subgraph_info,
1022                            oop orig) :
1023     _level(level),
1024     _record_klasses_only(record_klasses_only),
1025     _subgraph_info(subgraph_info),
1026     _referencing_obj(orig) {
1027     _last = _current;
1028     _current = this;
1029   }
1030   ~WalkOopAndArchiveClosure() {
1031     _current = _last;
1032   }
1033   void do_oop(narrowOop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
1034   void do_oop(      oop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
1035 
1036  protected:
1037   template <class T> void do_oop_work(T *p) {
1038     oop obj = RawAccess<>::oop_load(p);
1039     if (!CompressedOops::is_null(obj)) {
1040       size_t field_delta = pointer_delta(p, _referencing_obj, sizeof(char));
1041 
1042       if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
1043         ResourceMark rm;
1044         log_debug(cds, heap)("(%d) %s[" SIZE_FORMAT "] ==> " PTR_FORMAT " size " SIZE_FORMAT " %s", _level,
1045                              _referencing_obj->klass()->external_name(), field_delta,
1046                              p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
1047         if (log_is_enabled(Trace, cds, heap)) {
1048           LogTarget(Trace, cds, heap) log;
1049           LogStream out(log);
1050           obj->print_on(&out);
1051         }
1052       }
1053 
1054       bool success = HeapShared::archive_reachable_objects_from(
1055           _level + 1, _subgraph_info, obj);
1056       assert(success, "VM should have exited with unarchivable objects for _level > 1");
1057     }
1058   }
1059 
1060  public:
1061   static WalkOopAndArchiveClosure* current()  { return _current;              }
1062   oop referencing_obj()                       { return _referencing_obj;      }
1063   KlassSubGraphInfo* subgraph_info()          { return _subgraph_info;        }
1064 };
1065 
1066 WalkOopAndArchiveClosure* WalkOopAndArchiveClosure::_current = nullptr;
1067 
1068 // Checks if an oop has any non-null oop fields
1069 class PointsToOopsChecker : public BasicOopIterateClosure {
1070   bool _result;
1071 
1072   template <class T> void check(T *p) {
1073     _result |= (HeapAccess<>::oop_load(p) != nullptr);
1074   }
1075 
1076 public:
1077   PointsToOopsChecker() : _result(false) {}
1078   void do_oop(narrowOop *p) { check(p); }
1079   void do_oop(      oop *p) { check(p); }
1080   bool result() { return _result; }
1081 };
1082 
1083 HeapShared::CachedOopInfo HeapShared::make_cached_oop_info(oop obj) {
1084   WalkOopAndArchiveClosure* walker = WalkOopAndArchiveClosure::current();
1085   oop referrer = (walker == nullptr) ? nullptr : walker->referencing_obj();
1086   PointsToOopsChecker points_to_oops_checker;
1087   obj->oop_iterate(&points_to_oops_checker);
1088   return CachedOopInfo(referrer, points_to_oops_checker.result());
1089 }
1090 
1091 // (1) If orig_obj has not been archived yet, archive it.
1092 // (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
1093 //     trace all  objects that are reachable from it, and make sure these objects are archived.
1094 // (3) Record the klasses of all orig_obj and all reachable objects.
1095 bool HeapShared::archive_reachable_objects_from(int level,
1096                                                 KlassSubGraphInfo* subgraph_info,
1097                                                 oop orig_obj) {
1098   assert(orig_obj != nullptr, "must be");
1099 
1100   if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
1101     // This object has injected fields that cannot be supported easily, so we disallow them for now.
1102     // If you get an error here, you probably made a change in the JDK library that has added
1103     // these objects that are referenced (directly or indirectly) by static fields.
1104     ResourceMark rm;
1105     log_error(cds, heap)("Cannot archive object of class %s", orig_obj->klass()->external_name());
1106     MetaspaceShared::unrecoverable_writing_error();
1107   }
1108 
1109   // java.lang.Class instances cannot be included in an archived object sub-graph. We only support
1110   // them as Klass::_archived_mirror because they need to be specially restored at run time.
1111   //
1112   // If you get an error here, you probably made a change in the JDK library that has added a Class
1113   // object that is referenced (directly or indirectly) by static fields.
1114   if (java_lang_Class::is_instance(orig_obj) && subgraph_info != _default_subgraph_info) {
1115     log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
1116     MetaspaceShared::unrecoverable_writing_error();
1117   }
1118 
1119   if (has_been_seen_during_subgraph_recording(orig_obj)) {
1120     // orig_obj has already been archived and traced. Nothing more to do.
1121     return true;
1122   } else {
1123     set_has_been_seen_during_subgraph_recording(orig_obj);
1124   }
1125 
1126   bool already_archived = has_been_archived(orig_obj);
1127   bool record_klasses_only = already_archived;
1128   if (!already_archived) {
1129     ++_num_new_archived_objs;
1130     if (!archive_object(orig_obj)) {
1131       // Skip archiving the sub-graph referenced from the current entry field.
1132       ResourceMark rm;
1133       log_error(cds, heap)(
1134         "Cannot archive the sub-graph referenced from %s object ("
1135         PTR_FORMAT ") size " SIZE_FORMAT ", skipped.",
1136         orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
1137       if (level == 1) {
1138         // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1139         // as the Java code will take care of initializing this field dynamically.
1140         return false;
1141       } else {
1142         // We don't know how to handle an object that has been archived, but some of its reachable
1143         // objects cannot be archived. Bail out for now. We might need to fix this in the future if
1144         // we have a real use case.
1145         MetaspaceShared::unrecoverable_writing_error();
1146       }
1147     }
1148   }
1149 
1150   Klass *orig_k = orig_obj->klass();
1151   subgraph_info->add_subgraph_object_klass(orig_k);
1152 
1153   WalkOopAndArchiveClosure walker(level, record_klasses_only, subgraph_info, orig_obj);
1154   orig_obj->oop_iterate(&walker);
1155 
1156   if (CDSEnumKlass::is_enum_obj(orig_obj)) {
1157     CDSEnumKlass::handle_enum_obj(level + 1, subgraph_info, orig_obj);
1158   }
1159   return true;
1160 }
1161 
1162 //
1163 // Start from the given static field in a java mirror and archive the
1164 // complete sub-graph of java heap objects that are reached directly
1165 // or indirectly from the starting object by following references.
1166 // Sub-graph archiving restrictions (current):
1167 //
1168 // - All classes of objects in the archived sub-graph (including the
1169 //   entry class) must be boot class only.
1170 // - No java.lang.Class instance (java mirror) can be included inside
1171 //   an archived sub-graph. Mirror can only be the sub-graph entry object.
1172 //
1173 // The Java heap object sub-graph archiving process (see
1174 // WalkOopAndArchiveClosure):
1175 //
1176 // 1) Java object sub-graph archiving starts from a given static field
1177 // within a Class instance (java mirror). If the static field is a
1178 // reference field and points to a non-null java object, proceed to
1179 // the next step.
1180 //
1181 // 2) Archives the referenced java object. If an archived copy of the
1182 // current object already exists, updates the pointer in the archived
1183 // copy of the referencing object to point to the current archived object.
1184 // Otherwise, proceed to the next step.
1185 //
1186 // 3) Follows all references within the current java object and recursively
1187 // archive the sub-graph of objects starting from each reference.
1188 //
1189 // 4) Updates the pointer in the archived copy of referencing object to
1190 // point to the current archived object.
1191 //
1192 // 5) The Klass of the current java object is added to the list of Klasses
1193 // for loading and initializing before any object in the archived graph can
1194 // be accessed at runtime.
1195 //
1196 void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
1197                                                              const char* klass_name,
1198                                                              int field_offset,
1199                                                              const char* field_name) {
1200   assert(CDSConfig::is_dumping_heap(), "dump time only");
1201   assert(k->is_shared_boot_class(), "must be boot class");
1202 
1203   oop m = k->java_mirror();
1204 
1205   KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
1206   oop f = m->obj_field(field_offset);
1207 
1208   log_debug(cds, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
1209 
1210   if (!CompressedOops::is_null(f)) {
1211     if (log_is_enabled(Trace, cds, heap)) {
1212       LogTarget(Trace, cds, heap) log;
1213       LogStream out(log);
1214       f->print_on(&out);
1215     }
1216 
1217     bool success = archive_reachable_objects_from(1, subgraph_info, f);
1218     if (!success) {
1219       log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
1220                            klass_name, field_name);
1221     } else {
1222       // Note: the field value is not preserved in the archived mirror.
1223       // Record the field as a new subGraph entry point. The recorded
1224       // information is restored from the archive at runtime.
1225       subgraph_info->add_subgraph_entry_field(field_offset, f);
1226       log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(f));
1227     }
1228   } else {
1229     // The field contains null, we still need to record the entry point,
1230     // so it can be restored at runtime.
1231     subgraph_info->add_subgraph_entry_field(field_offset, nullptr);
1232   }
1233 }
1234 
1235 #ifndef PRODUCT
1236 class VerifySharedOopClosure: public BasicOopIterateClosure {
1237  public:
1238   void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
1239   void do_oop(      oop *p) { VerifySharedOopClosure::do_oop_work(p); }
1240 
1241  protected:
1242   template <class T> void do_oop_work(T *p) {
1243     oop obj = RawAccess<>::oop_load(p);
1244     if (!CompressedOops::is_null(obj)) {
1245       HeapShared::verify_reachable_objects_from(obj);
1246     }
1247   }
1248 };
1249 
1250 void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
1251   assert(CDSConfig::is_dumping_heap(), "dump time only");
1252   assert(k->is_shared_boot_class(), "must be boot class");
1253 
1254   oop m = k->java_mirror();
1255   oop f = m->obj_field(field_offset);
1256   if (!CompressedOops::is_null(f)) {
1257     verify_subgraph_from(f);
1258   }
1259 }
1260 
1261 void HeapShared::verify_subgraph_from(oop orig_obj) {
1262   if (!has_been_archived(orig_obj)) {
1263     // It's OK for the root of a subgraph to be not archived. See comments in
1264     // archive_reachable_objects_from().
1265     return;
1266   }
1267 
1268   // Verify that all objects reachable from orig_obj are archived.
1269   init_seen_objects_table();
1270   verify_reachable_objects_from(orig_obj);
1271   delete_seen_objects_table();
1272 }
1273 
1274 void HeapShared::verify_reachable_objects_from(oop obj) {
1275   _num_total_verifications ++;
1276   if (!has_been_seen_during_subgraph_recording(obj)) {
1277     set_has_been_seen_during_subgraph_recording(obj);
1278     assert(has_been_archived(obj), "must be");
1279     VerifySharedOopClosure walker;
1280     obj->oop_iterate(&walker);
1281   }
1282 }
1283 #endif
1284 
1285 // The "default subgraph" contains special objects (see heapShared.hpp) that
1286 // can be accessed before we load any Java classes (including java/lang/Class).
1287 // Make sure that these are only instances of the very few specific types
1288 // that we can handle.
1289 void HeapShared::check_default_subgraph_classes() {
1290   GrowableArray<Klass*>* klasses = _default_subgraph_info->subgraph_object_klasses();
1291   int num = klasses->length();
1292   for (int i = 0; i < num; i++) {
1293     Klass* subgraph_k = klasses->at(i);
1294     if (log_is_enabled(Info, cds, heap)) {
1295       ResourceMark rm;
1296       log_info(cds, heap)(
1297           "Archived object klass (default subgraph %d) => %s",
1298           i, subgraph_k->external_name());
1299     }
1300 
1301     Symbol* name = ArchiveBuilder::current()->get_source_addr(subgraph_k->name());
1302     guarantee(name == vmSymbols::java_lang_Class() ||
1303               name == vmSymbols::java_lang_String() ||
1304               name == vmSymbols::java_lang_ArithmeticException() ||
1305               name == vmSymbols::java_lang_NullPointerException() ||
1306               name == vmSymbols::java_lang_InternalError() ||
1307               name == vmSymbols::object_array_signature() ||
1308               name == vmSymbols::byte_array_signature() ||
1309               name == vmSymbols::char_array_signature(),
1310               "default subgraph can have only these objects");
1311   }
1312 }
1313 
1314 HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = nullptr;
1315 int HeapShared::_num_new_walked_objs;
1316 int HeapShared::_num_new_archived_objs;
1317 int HeapShared::_num_old_recorded_klasses;
1318 
1319 int HeapShared::_num_total_subgraph_recordings = 0;
1320 int HeapShared::_num_total_walked_objs = 0;
1321 int HeapShared::_num_total_archived_objs = 0;
1322 int HeapShared::_num_total_recorded_klasses = 0;
1323 int HeapShared::_num_total_verifications = 0;
1324 
1325 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
1326   return _seen_objects_table->get(obj) != nullptr;
1327 }
1328 
1329 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
1330   assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
1331   _seen_objects_table->put_when_absent(obj, true);
1332   _seen_objects_table->maybe_grow();
1333   ++ _num_new_walked_objs;
1334 }
1335 
1336 void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
1337   log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
1338   init_subgraph_info(k, is_full_module_graph);
1339   init_seen_objects_table();
1340   _num_new_walked_objs = 0;
1341   _num_new_archived_objs = 0;
1342   _num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
1343 }
1344 
1345 void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
1346   int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
1347     _num_old_recorded_klasses;
1348   log_info(cds, heap)("Done recording subgraph(s) for archived fields in %s: "
1349                       "walked %d objs, archived %d new objs, recorded %d classes",
1350                       class_name, _num_new_walked_objs, _num_new_archived_objs,
1351                       num_new_recorded_klasses);
1352 
1353   delete_seen_objects_table();
1354 
1355   _num_total_subgraph_recordings ++;
1356   _num_total_walked_objs      += _num_new_walked_objs;
1357   _num_total_archived_objs    += _num_new_archived_objs;
1358   _num_total_recorded_klasses +=  num_new_recorded_klasses;
1359 }
1360 
1361 class ArchivableStaticFieldFinder: public FieldClosure {
1362   InstanceKlass* _ik;
1363   Symbol* _field_name;
1364   bool _found;
1365   int _offset;
1366 public:
1367   ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
1368     _ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
1369 
1370   virtual void do_field(fieldDescriptor* fd) {
1371     if (fd->name() == _field_name) {
1372       assert(!_found, "fields can never be overloaded");
1373       if (is_reference_type(fd->field_type())) {
1374         _found = true;
1375         _offset = fd->offset();
1376       }
1377     }
1378   }
1379   bool found()     { return _found;  }
1380   int offset()     { return _offset; }
1381 };
1382 
1383 void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
1384                                             TRAPS) {
1385   for (int i = 0; fields[i].valid(); i++) {
1386     ArchivableStaticFieldInfo* info = &fields[i];
1387     TempNewSymbol klass_name =  SymbolTable::new_symbol(info->klass_name);
1388     TempNewSymbol field_name =  SymbolTable::new_symbol(info->field_name);
1389     ResourceMark rm; // for stringStream::as_string() etc.
1390 
1391 #ifndef PRODUCT
1392     bool is_test_class = (ArchiveHeapTestClass != nullptr) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
1393     const char* test_class_name = ArchiveHeapTestClass;
1394 #else
1395     bool is_test_class = false;
1396     const char* test_class_name = ""; // avoid C++ printf checks warnings.
1397 #endif
1398 
1399     if (is_test_class) {
1400       log_warning(cds)("Loading ArchiveHeapTestClass %s ...", test_class_name);
1401     }
1402 
1403     Klass* k = SystemDictionary::resolve_or_fail(klass_name, true, THREAD);
1404     if (HAS_PENDING_EXCEPTION) {
1405       CLEAR_PENDING_EXCEPTION;
1406       stringStream st;
1407       st.print("Fail to initialize archive heap: %s cannot be loaded by the boot loader", info->klass_name);
1408       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1409     }
1410 
1411     if (!k->is_instance_klass()) {
1412       stringStream st;
1413       st.print("Fail to initialize archive heap: %s is not an instance class", info->klass_name);
1414       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1415     }
1416 
1417     InstanceKlass* ik = InstanceKlass::cast(k);
1418     assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
1419            "Only support boot classes");
1420 
1421     if (is_test_class) {
1422       if (ik->module()->is_named()) {
1423         // We don't want ArchiveHeapTestClass to be abused to easily load/initialize arbitrary
1424         // core-lib classes. You need to at least append to the bootclasspath.
1425         stringStream st;
1426         st.print("ArchiveHeapTestClass %s is not in unnamed module", test_class_name);
1427         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1428       }
1429 
1430       if (ik->package() != nullptr) {
1431         // This restriction makes HeapShared::is_a_test_class_in_unnamed_module() easy.
1432         stringStream st;
1433         st.print("ArchiveHeapTestClass %s is not in unnamed package", test_class_name);
1434         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1435       }
1436     } else {
1437       if (ik->module()->name() != vmSymbols::java_base()) {
1438         // We don't want to deal with cases when a module is unavailable at runtime.
1439         // FUTURE -- load from archived heap only when module graph has not changed
1440         //           between dump and runtime.
1441         stringStream st;
1442         st.print("%s is not in java.base module", info->klass_name);
1443         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1444       }
1445     }
1446 
1447     if (is_test_class) {
1448       log_warning(cds)("Initializing ArchiveHeapTestClass %s ...", test_class_name);
1449     }
1450     ik->initialize(CHECK);
1451 
1452     ArchivableStaticFieldFinder finder(ik, field_name);
1453     ik->do_local_static_fields(&finder);
1454     if (!finder.found()) {
1455       stringStream st;
1456       st.print("Unable to find the static T_OBJECT field %s::%s", info->klass_name, info->field_name);
1457       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1458     }
1459 
1460     info->klass = ik;
1461     info->offset = finder.offset();
1462   }
1463 }
1464 
1465 void HeapShared::init_subgraph_entry_fields(TRAPS) {
1466   assert(HeapShared::can_write(), "must be");
1467   _dump_time_subgraph_info_table = new (mtClass)DumpTimeKlassSubGraphInfoTable();
1468   init_subgraph_entry_fields(archive_subgraph_entry_fields, CHECK);
1469   if (CDSConfig::is_dumping_full_module_graph()) {
1470     init_subgraph_entry_fields(fmg_archive_subgraph_entry_fields, CHECK);
1471   }
1472 }
1473 
1474 #ifndef PRODUCT
1475 void HeapShared::setup_test_class(const char* test_class_name) {
1476   ArchivableStaticFieldInfo* p = archive_subgraph_entry_fields;
1477   int num_slots = sizeof(archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
1478   assert(p[num_slots - 2].klass_name == nullptr, "must have empty slot that's patched below");
1479   assert(p[num_slots - 1].klass_name == nullptr, "must have empty slot that marks the end of the list");
1480 
1481   if (test_class_name != nullptr) {
1482     p[num_slots - 2].klass_name = test_class_name;
1483     p[num_slots - 2].field_name = ARCHIVE_TEST_FIELD_NAME;
1484   }
1485 }
1486 
1487 // See if ik is one of the test classes that are pulled in by -XX:ArchiveHeapTestClass
1488 // during runtime. This may be called before the module system is initialized so
1489 // we cannot rely on InstanceKlass::module(), etc.
1490 bool HeapShared::is_a_test_class_in_unnamed_module(Klass* ik) {
1491   if (_test_class != nullptr) {
1492     if (ik == _test_class) {
1493       return true;
1494     }
1495     Array<Klass*>* klasses = _test_class_record->subgraph_object_klasses();
1496     if (klasses == nullptr) {
1497       return false;
1498     }
1499 
1500     for (int i = 0; i < klasses->length(); i++) {
1501       Klass* k = klasses->at(i);
1502       if (k == ik) {
1503         Symbol* name;
1504         if (k->is_instance_klass()) {
1505           name = InstanceKlass::cast(k)->name();
1506         } else if (k->is_objArray_klass()) {
1507           Klass* bk = ObjArrayKlass::cast(k)->bottom_klass();
1508           if (!bk->is_instance_klass()) {
1509             return false;
1510           }
1511           name = bk->name();
1512         } else {
1513           return false;
1514         }
1515 
1516         // See KlassSubGraphInfo::check_allowed_klass() - only two types of
1517         // classes are allowed:
1518         //   (A) java.base classes (which must not be in the unnamed module)
1519         //   (B) test classes which must be in the unnamed package of the unnamed module.
1520         // So if we see a '/' character in the class name, it must be in (A);
1521         // otherwise it must be in (B).
1522         if (name->index_of_at(0, "/", 1)  >= 0) {
1523           return false; // (A)
1524         }
1525 
1526         return true; // (B)
1527       }
1528     }
1529   }
1530 
1531   return false;
1532 }
1533 #endif
1534 
1535 void HeapShared::init_for_dumping(TRAPS) {
1536   if (HeapShared::can_write()) {
1537     setup_test_class(ArchiveHeapTestClass);
1538     _dumped_interned_strings = new (mtClass)DumpedInternedStrings(INITIAL_TABLE_SIZE, MAX_TABLE_SIZE);
1539     init_subgraph_entry_fields(CHECK);
1540   }
1541 }
1542 
1543 void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
1544                                           bool is_full_module_graph) {
1545   _num_total_subgraph_recordings = 0;
1546   _num_total_walked_objs = 0;
1547   _num_total_archived_objs = 0;
1548   _num_total_recorded_klasses = 0;
1549   _num_total_verifications = 0;
1550 
1551   // For each class X that has one or more archived fields:
1552   // [1] Dump the subgraph of each archived field
1553   // [2] Create a list of all the class of the objects that can be reached
1554   //     by any of these static fields.
1555   //     At runtime, these classes are initialized before X's archived fields
1556   //     are restored by HeapShared::initialize_from_archived_subgraph().
1557   int i;
1558   for (int i = 0; fields[i].valid(); ) {
1559     ArchivableStaticFieldInfo* info = &fields[i];
1560     const char* klass_name = info->klass_name;
1561     start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
1562 
1563     // If you have specified consecutive fields of the same klass in
1564     // fields[], these will be archived in the same
1565     // {start_recording_subgraph ... done_recording_subgraph} pass to
1566     // save time.
1567     for (; fields[i].valid(); i++) {
1568       ArchivableStaticFieldInfo* f = &fields[i];
1569       if (f->klass_name != klass_name) {
1570         break;
1571       }
1572 
1573       archive_reachable_objects_from_static_field(f->klass, f->klass_name,
1574                                                   f->offset, f->field_name);
1575     }
1576     done_recording_subgraph(info->klass, klass_name);
1577   }
1578 
1579   log_info(cds, heap)("Archived subgraph records = %d",
1580                       _num_total_subgraph_recordings);
1581   log_info(cds, heap)("  Walked %d objects", _num_total_walked_objs);
1582   log_info(cds, heap)("  Archived %d objects", _num_total_archived_objs);
1583   log_info(cds, heap)("  Recorded %d klasses", _num_total_recorded_klasses);
1584 
1585 #ifndef PRODUCT
1586   for (int i = 0; fields[i].valid(); i++) {
1587     ArchivableStaticFieldInfo* f = &fields[i];
1588     verify_subgraph_from_static_field(f->klass, f->offset);
1589   }
1590   log_info(cds, heap)("  Verified %d references", _num_total_verifications);
1591 #endif
1592 }
1593 
1594 // Not all the strings in the global StringTable are dumped into the archive, because
1595 // some of those strings may be only referenced by classes that are excluded from
1596 // the archive. We need to explicitly mark the strings that are:
1597 //   [1] used by classes that WILL be archived;
1598 //   [2] included in the SharedArchiveConfigFile.
1599 void HeapShared::add_to_dumped_interned_strings(oop string) {
1600   assert_at_safepoint(); // DumpedInternedStrings uses raw oops
1601   assert(!ArchiveHeapWriter::is_string_too_large_to_archive(string), "must be");
1602   bool created;
1603   _dumped_interned_strings->put_if_absent(string, true, &created);
1604   if (created) {
1605     _dumped_interned_strings->maybe_grow();
1606   }
1607 }
1608 
1609 #ifndef PRODUCT
1610 // At dump-time, find the location of all the non-null oop pointers in an archived heap
1611 // region. This way we can quickly relocate all the pointers without using
1612 // BasicOopIterateClosure at runtime.
1613 class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
1614   void* _start;
1615   BitMap *_oopmap;
1616   int _num_total_oops;
1617   int _num_null_oops;
1618  public:
1619   FindEmbeddedNonNullPointers(void* start, BitMap* oopmap)
1620     : _start(start), _oopmap(oopmap), _num_total_oops(0),  _num_null_oops(0) {}
1621 
1622   virtual void do_oop(narrowOop* p) {
1623     assert(UseCompressedOops, "sanity");
1624     _num_total_oops ++;
1625     narrowOop v = *p;
1626     if (!CompressedOops::is_null(v)) {
1627       size_t idx = p - (narrowOop*)_start;
1628       _oopmap->set_bit(idx);
1629     } else {
1630       _num_null_oops ++;
1631     }
1632   }
1633   virtual void do_oop(oop* p) {
1634     assert(!UseCompressedOops, "sanity");
1635     _num_total_oops ++;
1636     if ((*p) != nullptr) {
1637       size_t idx = p - (oop*)_start;
1638       _oopmap->set_bit(idx);
1639     } else {
1640       _num_null_oops ++;
1641     }
1642   }
1643   int num_total_oops() const { return _num_total_oops; }
1644   int num_null_oops()  const { return _num_null_oops; }
1645 };
1646 #endif
1647 
1648 #ifndef PRODUCT
1649 ResourceBitMap HeapShared::calculate_oopmap(MemRegion region) {
1650   size_t num_bits = region.byte_size() / (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
1651   ResourceBitMap oopmap(num_bits);
1652 
1653   HeapWord* p   = region.start();
1654   HeapWord* end = region.end();
1655   FindEmbeddedNonNullPointers finder((void*)p, &oopmap);
1656 
1657   int num_objs = 0;
1658   while (p < end) {
1659     oop o = cast_to_oop(p);
1660     o->oop_iterate(&finder);
1661     p += o->size();
1662     ++ num_objs;
1663   }
1664 
1665   log_info(cds, heap)("calculate_oopmap: objects = %6d, oop fields = %7d (nulls = %7d)",
1666                       num_objs, finder.num_total_oops(), finder.num_null_oops());
1667   return oopmap;
1668 }
1669 
1670 #endif // !PRODUCT
1671 
1672 void HeapShared::count_allocation(size_t size) {
1673   _total_obj_count ++;
1674   _total_obj_size += size;
1675   for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
1676     if (size <= (size_t(1) << i)) {
1677       _alloc_count[i] ++;
1678       _alloc_size[i] += size;
1679       return;
1680     }
1681   }
1682 }
1683 
1684 static double avg_size(size_t size, size_t count) {
1685   double avg = 0;
1686   if (count > 0) {
1687     avg = double(size * HeapWordSize) / double(count);
1688   }
1689   return avg;
1690 }
1691 
1692 void HeapShared::print_stats() {
1693   size_t huge_count = _total_obj_count;
1694   size_t huge_size = _total_obj_size;
1695 
1696   for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
1697     size_t byte_size_limit = (size_t(1) << i) * HeapWordSize;
1698     size_t count = _alloc_count[i];
1699     size_t size = _alloc_size[i];
1700     log_info(cds, heap)(SIZE_FORMAT_W(8) " objects are <= " SIZE_FORMAT_W(-6)
1701                         " bytes (total " SIZE_FORMAT_W(8) " bytes, avg %8.1f bytes)",
1702                         count, byte_size_limit, size * HeapWordSize, avg_size(size, count));
1703     huge_count -= count;
1704     huge_size -= size;
1705   }
1706 
1707   log_info(cds, heap)(SIZE_FORMAT_W(8) " huge  objects               (total "  SIZE_FORMAT_W(8) " bytes"
1708                       ", avg %8.1f bytes)",
1709                       huge_count, huge_size * HeapWordSize,
1710                       avg_size(huge_size, huge_count));
1711   log_info(cds, heap)(SIZE_FORMAT_W(8) " total objects               (total "  SIZE_FORMAT_W(8) " bytes"
1712                       ", avg %8.1f bytes)",
1713                       _total_obj_count, _total_obj_size * HeapWordSize,
1714                       avg_size(_total_obj_size, _total_obj_count));
1715 }
1716 
1717 bool HeapShared::is_archived_boot_layer_available(JavaThread* current) {
1718   TempNewSymbol klass_name = SymbolTable::new_symbol(ARCHIVED_BOOT_LAYER_CLASS);
1719   InstanceKlass* k = SystemDictionary::find_instance_klass(current, klass_name, Handle(), Handle());
1720   if (k == nullptr) {
1721     return false;
1722   } else {
1723     TempNewSymbol field_name = SymbolTable::new_symbol(ARCHIVED_BOOT_LAYER_FIELD);
1724     TempNewSymbol field_signature = SymbolTable::new_symbol("Ljdk/internal/module/ArchivedBootLayer;");
1725     fieldDescriptor fd;
1726     if (k->find_field(field_name, field_signature, true, &fd) != nullptr) {
1727       oop m = k->java_mirror();
1728       oop f = m->obj_field(fd.offset());
1729       if (CompressedOops::is_null(f)) {
1730         return false;
1731       }
1732     } else {
1733       return false;
1734     }
1735   }
1736   return true;
1737 }
1738 
1739 #endif // INCLUDE_CDS_JAVA_HEAP