1 /*
   2  * Copyright (c) 2018, 2020, 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 "classfile/classLoaderData.hpp"
  27 #include "classfile/classLoaderDataShared.hpp"
  28 #include "classfile/javaClasses.inline.hpp"
  29 #include "classfile/moduleEntry.hpp"
  30 #include "classfile/stringTable.hpp"
  31 #include "classfile/symbolTable.hpp"
  32 #include "classfile/systemDictionary.hpp"
  33 #include "classfile/systemDictionaryShared.hpp"
  34 #include "classfile/vmSymbols.hpp"
  35 #include "gc/shared/gcLocker.hpp"
  36 #include "logging/log.hpp"
  37 #include "logging/logMessage.hpp"
  38 #include "logging/logStream.hpp"
  39 #include "memory/archiveBuilder.hpp"
  40 #include "memory/archiveUtils.hpp"
  41 #include "memory/filemap.hpp"
  42 #include "memory/heapShared.inline.hpp"
  43 #include "memory/iterator.inline.hpp"
  44 #include "memory/metadataFactory.hpp"
  45 #include "memory/metaspaceClosure.hpp"
  46 #include "memory/metaspaceShared.hpp"
  47 #include "memory/resourceArea.hpp"
  48 #include "memory/universe.hpp"
  49 #include "oops/compressedOops.inline.hpp"
  50 #include "oops/fieldStreams.inline.hpp"
  51 #include "oops/objArrayOop.hpp"
  52 #include "oops/oop.inline.hpp"
  53 #include "oops/oopHandle.hpp"
  54 #include "runtime/fieldDescriptor.inline.hpp"
  55 #include "runtime/init.hpp"
  56 #include "runtime/javaCalls.hpp"
  57 #include "runtime/safepointVerifiers.hpp"
  58 #include "utilities/bitMap.inline.hpp"
  59 #if INCLUDE_G1GC
  60 #include "gc/g1/g1CollectedHeap.hpp"
  61 #endif
  62 
  63 #if INCLUDE_CDS_JAVA_HEAP
  64 
  65 bool HeapShared::_closed_archive_heap_region_mapped = false;
  66 bool HeapShared::_open_archive_heap_region_mapped = false;
  67 bool HeapShared::_archive_heap_region_fixed = false;
  68 address   HeapShared::_narrow_oop_base;
  69 int       HeapShared::_narrow_oop_shift;
  70 DumpedInternedStrings *HeapShared::_dumped_interned_strings = NULL;
  71 
  72 //
  73 // If you add new entries to the following tables, you should know what you're doing!
  74 //
  75 
  76 // Entry fields for shareable subgraphs archived in the closed archive heap
  77 // region. Warning: Objects in the subgraphs should not have reference fields
  78 // assigned at runtime.
  79 static ArchivableStaticFieldInfo closed_archive_subgraph_entry_fields[] = {
  80   {"java/lang/Integer$IntegerCache",              "archivedCache"},
  81   {"java/lang/Long$LongCache",                    "archivedCache"},
  82   {"java/lang/Byte$ByteCache",                    "archivedCache"},
  83   {"java/lang/Short$ShortCache",                  "archivedCache"},
  84   {"java/lang/Character$CharacterCache",          "archivedCache"},
  85   {"java/util/jar/Attributes$Name",               "KNOWN_NAMES"},
  86   {"sun/util/locale/BaseLocale",                  "constantBaseLocales"},
  87 };
  88 // Entry fields for subgraphs archived in the open archive heap region.
  89 static ArchivableStaticFieldInfo open_archive_subgraph_entry_fields[] = {
  90   {"jdk/internal/module/ArchivedModuleGraph",     "archivedModuleGraph"},
  91   {"java/util/ImmutableCollections",              "archivedObjects"},
  92   {"java/lang/module/Configuration",              "EMPTY_CONFIGURATION"},
  93   {"jdk/internal/math/FDBigInteger",              "archivedCaches"},
  94 };
  95 
  96 // Entry fields for subgraphs archived in the open archive heap region (full module graph).
  97 static ArchivableStaticFieldInfo fmg_open_archive_subgraph_entry_fields[] = {
  98   {"jdk/internal/loader/ArchivedClassLoaders",    "archivedClassLoaders"},
  99   {"jdk/internal/module/ArchivedBootLayer",       "archivedBootLayer"},
 100   {"java/lang/Module$ArchivedData",               "archivedData"},
 101 };
 102 
 103 const static int num_closed_archive_subgraph_entry_fields =
 104   sizeof(closed_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
 105 const static int num_open_archive_subgraph_entry_fields =
 106   sizeof(open_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
 107 const static int num_fmg_open_archive_subgraph_entry_fields =
 108   sizeof(fmg_open_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
 109 
 110 static GrowableArrayCHeap<oop, mtClassShared>* _pending_roots = NULL;
 111 static objArrayOop _dumptime_roots = NULL;  // FIXME -- combine this with _runtime_roots??
 112 static narrowOop _runtime_roots_narrow;
 113 static OopHandle _runtime_roots;
 114 
 115 ////////////////////////////////////////////////////////////////
 116 //
 117 // Java heap object archiving support
 118 //
 119 ////////////////////////////////////////////////////////////////
 120 void HeapShared::fixup_mapped_heap_regions() {
 121   FileMapInfo *mapinfo = FileMapInfo::current_info();
 122   mapinfo->fixup_mapped_heap_regions();
 123   set_archive_heap_region_fixed();
 124   if (is_mapped()) {
 125     _runtime_roots = OopHandle(Universe::vm_global(), HeapShared::materialize_archived_object(_runtime_roots_narrow));
 126     if (!MetaspaceShared::use_full_module_graph()) {
 127       // Need to remove all the archived java.lang.Module objects from HeapShared::roots().
 128       ClassLoaderDataShared::clear_archived_oops();
 129     }
 130   }
 131   SystemDictionaryShared::update_archived_mirror_native_pointers();
 132 }
 133 
 134 unsigned HeapShared::oop_hash(oop const& p) {
 135   assert(!p->mark().has_bias_pattern(),
 136          "this object should never have been locked");  // so identity_hash won't safepoin
 137   unsigned hash = (unsigned)p->identity_hash();
 138   return hash;
 139 }
 140 
 141 static void reset_states(oop obj, TRAPS) {
 142   Handle h_obj(THREAD, obj);
 143   InstanceKlass* klass = InstanceKlass::cast(obj->klass());
 144   TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
 145   Symbol* method_sig = vmSymbols::void_method_signature();
 146 
 147   while (klass != NULL) {
 148     Method* method = klass->find_method(method_name, method_sig);
 149     if (method != NULL) {
 150       assert(method->is_private(), "must be");
 151       if (log_is_enabled(Debug, cds)) {
 152         ResourceMark rm(THREAD);
 153         log_debug(cds)("  calling %s", method->name_and_sig_as_C_string());
 154       }
 155       JavaValue result(T_VOID);
 156       JavaCalls::call_special(&result, h_obj, klass,
 157                               method_name, method_sig, CHECK);
 158     }
 159     klass = klass->java_super();
 160   }
 161 }
 162 
 163 void HeapShared::reset_archived_object_states(TRAPS) {
 164   assert(DumpSharedSpaces, "dump-time only");
 165   log_debug(cds)("Resetting platform loader");
 166   reset_states(SystemDictionary::java_platform_loader(), THREAD);
 167   log_debug(cds)("Resetting system loader");
 168   reset_states(SystemDictionary::java_system_loader(), THREAD);
 169 }
 170 
 171 HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = NULL;
 172 oop HeapShared::find_archived_heap_object(oop obj) {
 173   assert(DumpSharedSpaces, "dump-time only");
 174   ArchivedObjectCache* cache = archived_object_cache();
 175   oop* p = cache->get(obj);
 176   if (p != NULL) {
 177     return *p;
 178   } else {
 179     return NULL;
 180   }
 181 }
 182 
 183 int HeapShared::append_root(oop obj) {
 184   assert(DumpSharedSpaces, "dump-time only");
 185 
 186   // No GC should happen since we aren't scanning _pending_roots.
 187   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 188 
 189   if (_pending_roots == NULL) {
 190     _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
 191   }
 192 
 193   return _pending_roots->append(obj);
 194 }
 195 
 196 objArrayOop HeapShared::roots() {
 197   if (DumpSharedSpaces) {
 198     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 199     return _dumptime_roots;
 200   } else {
 201     assert(UseSharedSpaces, "must be");
 202     objArrayOop roots = (objArrayOop)_runtime_roots.resolve();
 203     assert(roots != NULL, "should have been initialized");
 204     return roots;
 205   }
 206 }
 207 
 208 void HeapShared::set_roots(narrowOop roots) {
 209   assert(UseSharedSpaces, "runtime only");
 210   assert(open_archive_heap_region_mapped(), "must be");
 211   _runtime_roots_narrow = roots;
 212 }
 213 
 214 oop HeapShared::get_root(int index, bool clear) {
 215   assert(index >= 0, "sanity");
 216   if (DumpSharedSpaces) {
 217     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 218     assert(_pending_roots != NULL, "sanity");
 219     return _pending_roots->at(index);
 220   } else {
 221     assert(UseSharedSpaces, "must be");
 222     assert(!_runtime_roots.is_empty(), "must have loaded shared heap");
 223     oop result = roots()->obj_at(index);
 224     if (clear) {
 225       clear_root(index);
 226     }
 227     return result;
 228   }
 229 }
 230 
 231 void HeapShared::clear_root(int index) {
 232   assert(index >= 0, "sanity");
 233   assert(UseSharedSpaces, "must be");
 234   if (open_archive_heap_region_mapped()) {
 235     if (log_is_enabled(Debug, cds, heap)) {
 236       oop old = roots()->obj_at(index);
 237       log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
 238     }
 239     roots()->obj_at_put(index, NULL);
 240   }
 241 }
 242 
 243 oop HeapShared::archive_heap_object(oop obj, Thread* THREAD) {
 244   assert(DumpSharedSpaces, "dump-time only");
 245 
 246   oop ao = find_archived_heap_object(obj);
 247   if (ao != NULL) {
 248     // already archived
 249     return ao;
 250   }
 251 
 252   int len = obj->size();
 253   if (G1CollectedHeap::heap()->is_archive_alloc_too_large(len)) {
 254     log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
 255                          p2i(obj), (size_t)obj->size());
 256     return NULL;
 257   }
 258 
 259   oop archived_oop = (oop)G1CollectedHeap::heap()->archive_mem_allocate(len);
 260   if (archived_oop != NULL) {
 261     Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), cast_from_oop<HeapWord*>(archived_oop), len);
 262     MetaspaceShared::relocate_klass_ptr(archived_oop);
 263     // Reinitialize markword to remove age/marking/locking/etc.
 264     //
 265     // We need to retain the identity_hash, because it may have been used by some hashtables
 266     // in the shared heap. This also has the side effect of pre-initializing the
 267     // identity_hash for all shared objects, so they are less likely to be written
 268     // into during run time, increasing the potential of memory sharing.
 269     int hash_original = obj->identity_hash();
 270     archived_oop->set_mark(markWord::prototype().copy_set_hash(hash_original));
 271     assert(archived_oop->mark().is_unlocked(), "sanity");
 272 
 273     DEBUG_ONLY(int hash_archived = archived_oop->identity_hash());
 274     assert(hash_original == hash_archived, "Different hash codes: original %x, archived %x", hash_original, hash_archived);
 275 
 276     ArchivedObjectCache* cache = archived_object_cache();
 277     cache->put(obj, archived_oop);
 278     if (log_is_enabled(Debug, cds, heap)) {
 279       ResourceMark rm;
 280       log_debug(cds, heap)("Archived heap object " PTR_FORMAT " ==> " PTR_FORMAT " : %s",
 281                            p2i(obj), p2i(archived_oop), obj->klass()->external_name());
 282     }
 283   } else {
 284     log_error(cds, heap)(
 285       "Cannot allocate space for object " PTR_FORMAT " in archived heap region",
 286       p2i(obj));
 287     vm_exit(1);
 288   }
 289   return archived_oop;
 290 }
 291 
 292 oop HeapShared::materialize_archived_object(narrowOop v) {
 293   assert(archive_heap_region_fixed(),
 294          "must be called after archive heap regions are fixed");
 295   if (!CompressedOops::is_null(v)) {
 296     oop obj = HeapShared::decode_from_archive(v);
 297     return G1CollectedHeap::heap()->materialize_archived_object(obj);
 298   }
 299   return NULL;
 300 }
 301 
 302 void HeapShared::archive_klass_objects(Thread* THREAD) {
 303   GrowableArray<Klass*>* klasses = MetaspaceShared::collected_klasses();
 304   assert(klasses != NULL, "sanity");
 305   for (int i = 0; i < klasses->length(); i++) {
 306     Klass* k = klasses->at(i);
 307 
 308     // archive mirror object
 309     java_lang_Class::archive_mirror(k, CHECK);
 310 
 311     // archive the resolved_referenes array
 312     if (k->is_instance_klass()) {
 313       InstanceKlass* ik = InstanceKlass::cast(k);
 314       ik->constants()->archive_resolved_references(THREAD);
 315     }
 316   }
 317 }
 318 
 319 void HeapShared::run_full_gc_in_vm_thread() {
 320   if (is_heap_object_archiving_allowed()) {
 321     // Avoid fragmentation while archiving heap objects.
 322     // We do this inside a safepoint, so that no further allocation can happen after GC
 323     // has finished.
 324     if (GCLocker::is_active()) {
 325       // Just checking for safety ...
 326       // This should not happen during -Xshare:dump. If you see this, probably the Java core lib
 327       // has been modified such that JNI code is executed in some clean up threads after
 328       // we have finished class loading.
 329       log_warning(cds)("GC locker is held, unable to start extra compacting GC. This may produce suboptimal results.");
 330     } else {
 331       log_info(cds)("Run GC ...");
 332       Universe::heap()->collect_as_vm_thread(GCCause::_archive_time_gc);
 333       log_info(cds)("Run GC done");
 334     }
 335   }
 336 }
 337 
 338 // Returns an objArray that contains all the roots of the archived objects
 339 void HeapShared::archive_java_heap_objects(GrowableArray<MemRegion> *closed,
 340                                            GrowableArray<MemRegion> *open) {
 341   if (!is_heap_object_archiving_allowed()) {
 342     log_info(cds)(
 343       "Archived java heap is not supported as UseG1GC, "
 344       "UseCompressedOops and UseCompressedClassPointers are required."
 345       "Current settings: UseG1GC=%s, UseCompressedOops=%s, UseCompressedClassPointers=%s.",
 346       BOOL_TO_STR(UseG1GC), BOOL_TO_STR(UseCompressedOops),
 347       BOOL_TO_STR(UseCompressedClassPointers));
 348     return;
 349   }
 350 
 351   G1HeapVerifier::verify_ready_for_archiving();
 352 
 353   {
 354     NoSafepointVerifier nsv;
 355 
 356     // Cache for recording where the archived objects are copied to
 357     create_archived_object_cache();
 358 
 359     log_info(cds)("Dumping objects to closed archive heap region ...");
 360     copy_closed_archive_heap_objects(closed);
 361 
 362     log_info(cds)("Dumping objects to open archive heap region ...");
 363     copy_open_archive_heap_objects(open);
 364 
 365     destroy_archived_object_cache();
 366   }
 367 
 368   G1HeapVerifier::verify_archive_regions();
 369 }
 370 
 371 void HeapShared::copy_closed_archive_heap_objects(
 372                                     GrowableArray<MemRegion> * closed_archive) {
 373   assert(is_heap_object_archiving_allowed(), "Cannot archive java heap objects");
 374 
 375   Thread* THREAD = Thread::current();
 376   G1CollectedHeap::heap()->begin_archive_alloc_range();
 377 
 378   // Archive interned string objects
 379   StringTable::write_to_archive(_dumped_interned_strings);
 380 
 381   archive_object_subgraphs(closed_archive_subgraph_entry_fields,
 382                            num_closed_archive_subgraph_entry_fields,
 383                            true /* is_closed_archive */,
 384                            false /* is_full_module_graph */,
 385                            THREAD);
 386 
 387   G1CollectedHeap::heap()->end_archive_alloc_range(closed_archive,
 388                                                    os::vm_allocation_granularity());
 389 }
 390 
 391 void HeapShared::copy_open_archive_heap_objects(
 392                                     GrowableArray<MemRegion> * open_archive) {
 393   assert(is_heap_object_archiving_allowed(), "Cannot archive java heap objects");
 394 
 395   Thread* THREAD = Thread::current();
 396   G1CollectedHeap::heap()->begin_archive_alloc_range(true /* open */);
 397 
 398   java_lang_Class::archive_basic_type_mirrors(THREAD);
 399 
 400   archive_klass_objects(THREAD);
 401 
 402   archive_object_subgraphs(open_archive_subgraph_entry_fields,
 403                            num_open_archive_subgraph_entry_fields,
 404                            false /* is_closed_archive */,
 405                            false /* is_full_module_graph */,
 406                            THREAD);
 407   if (MetaspaceShared::use_full_module_graph()) {
 408     archive_object_subgraphs(fmg_open_archive_subgraph_entry_fields,
 409                              num_fmg_open_archive_subgraph_entry_fields,
 410                              false /* is_closed_archive */,
 411                              true /* is_full_module_graph */,
 412                              THREAD);
 413     ClassLoaderDataShared::init_archived_oops();
 414   }
 415 
 416   copy_roots();
 417 
 418   G1CollectedHeap::heap()->end_archive_alloc_range(open_archive,
 419                                                    os::vm_allocation_granularity());
 420 }
 421 
 422 // Copy _pending_archive_roots into an objArray
 423 void HeapShared::copy_roots() {
 424   int length = _pending_roots != NULL ? _pending_roots->length() : 0;
 425   int size = objArrayOopDesc::object_size(length);
 426   Klass *k = Universe::objectArrayKlassObj(); // already relocated to point to archived klass
 427   HeapWord* mem = G1CollectedHeap::heap()->archive_mem_allocate(size);
 428 
 429   memset(mem, 0, size * BytesPerWord); // Is this correct??
 430   {
 431     // This is copied from MemAllocator::finish
 432     if (UseBiasedLocking) {
 433       oopDesc::set_mark(mem, k->prototype_header());
 434     } else {
 435       oopDesc::set_mark(mem, markWord::prototype());
 436     }
 437     oopDesc::release_set_klass(mem, k);
 438   }
 439   {
 440     // This is copied from ObjArrayAllocator::initialize
 441     arrayOopDesc::set_length(mem, length);
 442   }
 443 
 444   _dumptime_roots = (objArrayOop)mem;
 445   for (int i = 0; i < length; i++) {
 446     _dumptime_roots->obj_at_put(i, _pending_roots->at(i));
 447   }
 448   log_info(cds)("archived obj roots[%d] = %d words, klass = %p, obj = %p", length, size, k, mem);
 449 }
 450 
 451 void HeapShared::init_narrow_oop_decoding(address base, int shift) {
 452   _narrow_oop_base = base;
 453   _narrow_oop_shift = shift;
 454 }
 455 
 456 //
 457 // Subgraph archiving support
 458 //
 459 HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = NULL;
 460 HeapShared::RunTimeKlassSubGraphInfoTable   HeapShared::_run_time_subgraph_info_table;
 461 
 462 // Get the subgraph_info for Klass k. A new subgraph_info is created if
 463 // there is no existing one for k. The subgraph_info records the relocated
 464 // Klass* of the original k.
 465 KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
 466   assert(DumpSharedSpaces, "dump time only");
 467   bool created;
 468   Klass* relocated_k = MetaspaceShared::get_relocated_klass(k);
 469   KlassSubGraphInfo* info =
 470     _dump_time_subgraph_info_table->put_if_absent(relocated_k, KlassSubGraphInfo(relocated_k, is_full_module_graph),
 471                                                   &created);
 472   assert(created, "must not initialize twice");
 473   return info;
 474 }
 475 
 476 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
 477   assert(DumpSharedSpaces, "dump time only");
 478   Klass* relocated_k = MetaspaceShared::get_relocated_klass(k);
 479   KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(relocated_k);
 480   assert(info != NULL, "must have been initialized");
 481   return info;
 482 }
 483 
 484 // Add an entry field to the current KlassSubGraphInfo.
 485 void KlassSubGraphInfo::add_subgraph_entry_field(
 486       int static_field_offset, oop v, bool is_closed_archive) {
 487   assert(DumpSharedSpaces, "dump time only");
 488   if (_subgraph_entry_fields == NULL) {
 489     _subgraph_entry_fields =
 490       new(ResourceObj::C_HEAP, mtClass) GrowableArray<int>(10, mtClass);
 491   }
 492   _subgraph_entry_fields->append(static_field_offset);
 493   _subgraph_entry_fields->append(HeapShared::append_root(v));
 494   _subgraph_entry_fields->append(is_closed_archive ? 1 : 0);
 495 }
 496 
 497 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
 498 // Only objects of boot classes can be included in sub-graph.
 499 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k, Klass *relocated_k) {
 500   assert(DumpSharedSpaces, "dump time only");
 501   assert(relocated_k == MetaspaceShared::get_relocated_klass(orig_k),
 502          "must be the relocated Klass in the shared space");
 503 
 504   if (_subgraph_object_klasses == NULL) {
 505     _subgraph_object_klasses =
 506       new(ResourceObj::C_HEAP, mtClass) GrowableArray<Klass*>(50, mtClass);
 507   }
 508 
 509   assert(ArchiveBuilder::singleton()->is_in_buffer_space(relocated_k), "must be a shared class");
 510 
 511   if (_k == relocated_k) {
 512     // Don't add the Klass containing the sub-graph to it's own klass
 513     // initialization list.
 514     return;
 515   }
 516 
 517   if (relocated_k->is_instance_klass()) {
 518     assert(InstanceKlass::cast(relocated_k)->is_shared_boot_class(),
 519           "must be boot class");
 520     // SystemDictionary::xxx_klass() are not updated, need to check
 521     // the original Klass*
 522     if (orig_k == SystemDictionary::String_klass() ||
 523         orig_k == SystemDictionary::Object_klass()) {
 524       // Initialized early during VM initialization. No need to be added
 525       // to the sub-graph object class list.
 526       return;
 527     }
 528   } else if (relocated_k->is_objArray_klass()) {
 529     Klass* abk = ObjArrayKlass::cast(relocated_k)->bottom_klass();
 530     if (abk->is_instance_klass()) {
 531       assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
 532             "must be boot class");
 533     }
 534     if (relocated_k == Universe::objectArrayKlassObj()) {
 535       // Initialized early during Universe::genesis. No need to be added
 536       // to the list.
 537       return;
 538     }
 539   } else {
 540     assert(relocated_k->is_typeArray_klass(), "must be");
 541     // Primitive type arrays are created early during Universe::genesis.
 542     return;
 543   }
 544 
 545   if (log_is_enabled(Debug, cds, heap)) {
 546     if (!_subgraph_object_klasses->contains(relocated_k)) {
 547       ResourceMark rm;
 548       log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
 549     }
 550   }
 551 
 552   _subgraph_object_klasses->append_if_missing(relocated_k);
 553   _has_non_early_klasses |= is_non_early_klass(orig_k);
 554 }
 555 
 556 bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
 557   if (k->is_objArray_klass()) {
 558     k = ObjArrayKlass::cast(k)->bottom_klass();
 559   }
 560   if (k->is_instance_klass()) {
 561     if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
 562       ResourceMark rm;
 563       log_info(cds, heap)("non-early: %s", k->external_name());
 564       return true;
 565     } else {
 566       return false;
 567     }
 568   } else {
 569     return false;
 570   }
 571 }
 572 
 573 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
 574 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
 575   _k = info->klass();
 576   _entry_field_records = NULL;
 577   _subgraph_object_klasses = NULL;
 578   _is_full_module_graph = info->is_full_module_graph();
 579   _has_non_early_klasses = info->has_non_early_klasses();
 580 
 581   if (_has_non_early_klasses) {
 582     ResourceMark rm;
 583     log_info(cds, heap)(
 584           "Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
 585           _k->external_name());
 586   }
 587 
 588   // populate the entry fields
 589   GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
 590   if (entry_fields != NULL) {
 591     int num_entry_fields = entry_fields->length();
 592     assert(num_entry_fields % 3 == 0, "sanity");
 593     _entry_field_records =
 594       MetaspaceShared::new_ro_array<int>(num_entry_fields);
 595     for (int i = 0 ; i < num_entry_fields; i++) {
 596       _entry_field_records->at_put(i, entry_fields->at(i));
 597     }
 598   }
 599 
 600   // the Klasses of the objects in the sub-graphs
 601   GrowableArray<Klass*>* subgraph_object_klasses = info->subgraph_object_klasses();
 602   if (subgraph_object_klasses != NULL) {
 603     int num_subgraphs_klasses = subgraph_object_klasses->length();
 604     _subgraph_object_klasses =
 605       MetaspaceShared::new_ro_array<Klass*>(num_subgraphs_klasses);
 606     for (int i = 0; i < num_subgraphs_klasses; i++) {
 607       Klass* subgraph_k = subgraph_object_klasses->at(i);
 608       if (log_is_enabled(Info, cds, heap)) {
 609         ResourceMark rm;
 610         log_info(cds, heap)(
 611           "Archived object klass %s (%2d) => %s",
 612           _k->external_name(), i, subgraph_k->external_name());
 613       }
 614       _subgraph_object_klasses->at_put(i, subgraph_k);
 615       ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(i));
 616     }
 617   }
 618 
 619   ArchivePtrMarker::mark_pointer(&_k);
 620   ArchivePtrMarker::mark_pointer(&_entry_field_records);
 621   ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
 622 }
 623 
 624 struct CopyKlassSubGraphInfoToArchive : StackObj {
 625   CompactHashtableWriter* _writer;
 626   CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
 627 
 628   bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
 629     if (info.subgraph_object_klasses() != NULL || info.subgraph_entry_fields() != NULL) {
 630       ArchivedKlassSubGraphInfoRecord* record =
 631         (ArchivedKlassSubGraphInfoRecord*)MetaspaceShared::read_only_space_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
 632       record->init(&info);
 633 
 634       unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary(klass);
 635       u4 delta = MetaspaceShared::object_delta_u4(record);
 636       _writer->add(hash, delta);
 637     }
 638     return true; // keep on iterating
 639   }
 640 };
 641 
 642 // Build the records of archived subgraph infos, which include:
 643 // - Entry points to all subgraphs from the containing class mirror. The entry
 644 //   points are static fields in the mirror. For each entry point, the field
 645 //   offset, value and is_closed_archive flag are recorded in the sub-graph
 646 //   info. The value is stored back to the corresponding field at runtime.
 647 // - A list of klasses that need to be loaded/initialized before archived
 648 //   java object sub-graph can be accessed at runtime.
 649 void HeapShared::write_subgraph_info_table() {
 650   // Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
 651   DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
 652   CompactHashtableStats stats;
 653 
 654   _run_time_subgraph_info_table.reset();
 655 
 656   CompactHashtableWriter writer(d_table->_count, &stats);
 657   CopyKlassSubGraphInfoToArchive copy(&writer);
 658   d_table->iterate(&copy);
 659 
 660   writer.dump(&_run_time_subgraph_info_table, "subgraphs");
 661 }
 662 
 663 void HeapShared::serialize_subgraph_info_table_header(SerializeClosure* soc) {
 664   _run_time_subgraph_info_table.serialize_header(soc);
 665 }
 666 
 667 static void verify_the_heap(Klass* k, const char* which) {
 668   if (VerifyArchivedFields) {
 669     ResourceMark rm;
 670     log_info(cds, heap)("Verify heap %s initializing static field(s) in %s",
 671                         which, k->external_name());
 672     VM_Verify verify_op;
 673     VMThread::execute(&verify_op);
 674 #if 0
 675     // For some reason, this causes jtreg to lock up with
 676     // "jtreg -vmoptions:-XX:+VerifyArchivedFields HelloTest.java"
 677     if (is_init_completed()) {
 678       FlagSetting fs1(VerifyBeforeGC, true);
 679       FlagSetting fs2(VerifyDuringGC, true);
 680       FlagSetting fs3(VerifyAfterGC,  true);
 681       Universe::heap()->collect(GCCause::_java_lang_system_gc);
 682     }
 683 #endif
 684   }
 685 }
 686 
 687 // Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
 688 // have a valid klass. I.e., oopDesc::klass() must have already been resolved.
 689 //
 690 // Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
 691 // ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
 692 // this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
 693 void HeapShared::resolve_classes(TRAPS) {
 694   if (!is_mapped()) {
 695     return; // nothing to do
 696   }
 697   resolve_classes_for_subgraphs(closed_archive_subgraph_entry_fields,
 698                                 num_closed_archive_subgraph_entry_fields,
 699                                 CHECK);
 700   resolve_classes_for_subgraphs(open_archive_subgraph_entry_fields,
 701                                 num_open_archive_subgraph_entry_fields,
 702                                 CHECK);
 703   resolve_classes_for_subgraphs(fmg_open_archive_subgraph_entry_fields,
 704                                 num_fmg_open_archive_subgraph_entry_fields,
 705                                 CHECK);
 706 }
 707 
 708 void HeapShared::resolve_classes_for_subgraphs(ArchivableStaticFieldInfo fields[],
 709                                                int num, TRAPS) {
 710   for (int i = 0; i < num; i++) {
 711     ArchivableStaticFieldInfo* info = &fields[i];
 712     TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
 713     InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
 714     assert(k != NULL && k->is_shared_boot_class(), "sanity");
 715     resolve_classes_for_subgraph_of(k, CHECK);
 716   }
 717 }
 718 
 719 void HeapShared::resolve_classes_for_subgraph_of(Klass* k, TRAPS) {
 720  const ArchivedKlassSubGraphInfoRecord* record = resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
 721  if (HAS_PENDING_EXCEPTION) {
 722    CLEAR_PENDING_EXCEPTION;
 723  }
 724  if (record == NULL) {
 725    clear_archived_roots_of(k);
 726  }
 727 }
 728 
 729 void HeapShared::initialize_from_archived_subgraph(Klass* k, TRAPS) {
 730   if (!is_mapped()) {
 731     return; // nothing to do
 732   }
 733 
 734   const ArchivedKlassSubGraphInfoRecord* record =
 735     resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
 736 
 737   if (HAS_PENDING_EXCEPTION) {
 738     CLEAR_PENDING_EXCEPTION;
 739     // None of the field value will be set if there was an exception when initializing the classes.
 740     // The java code will not see any of the archived objects in the
 741     // subgraphs referenced from k in this case.
 742     return;
 743   }
 744 
 745   if (record != NULL) {
 746     init_archived_fields_for(k, record, THREAD);
 747   }
 748 }
 749 
 750 const ArchivedKlassSubGraphInfoRecord*
 751 HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
 752   assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
 753 
 754   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary(k);
 755   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 756 
 757   // Initialize from archived data. Currently this is done only
 758   // during VM initialization time. No lock is needed.
 759   if (record != NULL) {
 760     if (record->is_full_module_graph() && !MetaspaceShared::use_full_module_graph()) {
 761       if (log_is_enabled(Info, cds, heap)) {
 762         ResourceMark rm;
 763         log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
 764                             k->external_name());
 765       }
 766       return NULL;
 767     }
 768 
 769     if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
 770       if (log_is_enabled(Info, cds, heap)) {
 771         ResourceMark rm;
 772         log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
 773                             k->external_name());
 774       }
 775       return NULL;
 776     }
 777 
 778     resolve_or_init(k, do_init, CHECK_NULL);
 779 
 780     // Load/link/initialize the klasses of the objects in the subgraph.
 781     // NULL class loader is used.
 782     Array<Klass*>* klasses = record->subgraph_object_klasses();
 783     if (klasses != NULL) {
 784       for (int i = 0; i < klasses->length(); i++) {
 785         resolve_or_init(klasses->at(i), do_init, CHECK_NULL);
 786       }
 787     }
 788   }
 789 
 790   return record;
 791 }
 792 
 793 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
 794   if (!do_init) {
 795     if (k->class_loader_data() == NULL) {
 796       Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
 797       assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
 798     }
 799   } else {
 800     assert(k->class_loader_data() != NULL, "must have been resolved by HeapShared::resolve_classes");
 801     if (k->is_instance_klass()) {
 802       InstanceKlass* ik = InstanceKlass::cast(k);
 803       ik->initialize(CHECK);
 804     } else if (k->is_objArray_klass()) {
 805       ObjArrayKlass* oak = ObjArrayKlass::cast(k);
 806       oak->initialize(CHECK);
 807     }
 808   }
 809 }
 810 
 811 void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record, TRAPS) {
 812   verify_the_heap(k, "before");
 813 
 814   // Load the subgraph entry fields from the record and store them back to
 815   // the corresponding fields within the mirror.
 816   oop m = k->java_mirror();
 817   Array<int>* entry_field_records = record->entry_field_records();
 818   if (entry_field_records != NULL) {
 819     int efr_len = entry_field_records->length();
 820     assert(efr_len % 3 == 0, "sanity");
 821     for (int i = 0; i < efr_len; i += 3) {
 822       int field_offset = entry_field_records->at(i);
 823       int root_index = entry_field_records->at(i+1);
 824       int is_closed_archive = entry_field_records->at(i+2);
 825       oop v = get_root(root_index, /*clear=*/true);
 826       m->obj_field_put(field_offset, v);
 827       log_debug(cds, heap)("  " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
 828     }
 829 
 830     // Done. Java code can see the archived sub-graphs referenced from k's
 831     // mirror after this point.
 832     if (log_is_enabled(Info, cds, heap)) {
 833       ResourceMark rm;
 834       log_info(cds, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s",
 835                           k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "");
 836     }
 837   }
 838 
 839   verify_the_heap(k, "after ");
 840 }
 841 
 842 void HeapShared::clear_archived_roots_of(Klass* k) {
 843   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary(k);
 844   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 845   if (record != NULL) {
 846     Array<int>* entry_field_records = record->entry_field_records();
 847     if (entry_field_records != NULL) {
 848       int efr_len = entry_field_records->length();
 849       assert(efr_len % 3 == 0, "sanity");
 850       for (int i = 0; i < efr_len; i += 3) {
 851         int root_index = entry_field_records->at(i+1);
 852         clear_root(root_index);
 853       }
 854     }
 855   }
 856 }
 857 
 858 class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
 859   int _level;
 860   bool _is_closed_archive;
 861   bool _record_klasses_only;
 862   KlassSubGraphInfo* _subgraph_info;
 863   oop _orig_referencing_obj;
 864   oop _archived_referencing_obj;
 865   Thread* _thread;
 866  public:
 867   WalkOopAndArchiveClosure(int level,
 868                            bool is_closed_archive,
 869                            bool record_klasses_only,
 870                            KlassSubGraphInfo* subgraph_info,
 871                            oop orig, oop archived, TRAPS) :
 872     _level(level), _is_closed_archive(is_closed_archive),
 873     _record_klasses_only(record_klasses_only),
 874     _subgraph_info(subgraph_info),
 875     _orig_referencing_obj(orig), _archived_referencing_obj(archived),
 876     _thread(THREAD) {}
 877   void do_oop(narrowOop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
 878   void do_oop(      oop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
 879 
 880  protected:
 881   template <class T> void do_oop_work(T *p) {
 882     oop obj = RawAccess<>::oop_load(p);
 883     if (!CompressedOops::is_null(obj)) {
 884       assert(!HeapShared::is_archived_object(obj),
 885              "original objects must not point to archived objects");
 886 
 887       size_t field_delta = pointer_delta(p, _orig_referencing_obj, sizeof(char));
 888       T* new_p = (T*)(cast_from_oop<address>(_archived_referencing_obj) + field_delta);
 889       Thread* THREAD = _thread;
 890 
 891       if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
 892         ResourceMark rm;
 893         log_debug(cds, heap)("(%d) %s[" SIZE_FORMAT "] ==> " PTR_FORMAT " size %d %s", _level,
 894                              _orig_referencing_obj->klass()->external_name(), field_delta,
 895                              p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
 896         LogTarget(Trace, cds, heap) log;
 897         LogStream out(log);
 898         obj->print_on(&out);
 899       }
 900 
 901       oop archived = HeapShared::archive_reachable_objects_from(
 902           _level + 1, _subgraph_info, obj, _is_closed_archive, THREAD);
 903       assert(archived != NULL, "VM should have exited with unarchivable objects for _level > 1");
 904       assert(HeapShared::is_archived_object(archived), "must be");
 905 
 906       if (!_record_klasses_only) {
 907         // Update the reference in the archived copy of the referencing object.
 908         log_debug(cds, heap)("(%d) updating oop @[" PTR_FORMAT "] " PTR_FORMAT " ==> " PTR_FORMAT,
 909                              _level, p2i(new_p), p2i(obj), p2i(archived));
 910         RawAccess<IS_NOT_NULL>::oop_store(new_p, archived);
 911       }
 912     }
 913   }
 914 };
 915 
 916 void HeapShared::check_closed_archive_heap_region_object(InstanceKlass* k,
 917                                                          Thread* THREAD) {
 918   // Check fields in the object
 919   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
 920     if (!fs.access_flags().is_static()) {
 921       BasicType ft = fs.field_descriptor().field_type();
 922       if (!fs.access_flags().is_final() && is_reference_type(ft)) {
 923         ResourceMark rm(THREAD);
 924         log_warning(cds, heap)(
 925           "Please check reference field in %s instance in closed archive heap region: %s %s",
 926           k->external_name(), (fs.name())->as_C_string(),
 927           (fs.signature())->as_C_string());
 928       }
 929     }
 930   }
 931 }
 932 
 933 void HeapShared::check_module_oop(oop orig_module_obj) {
 934   assert(DumpSharedSpaces, "must be");
 935   assert(java_lang_Module::is_instance(orig_module_obj), "must be");
 936   ModuleEntry* orig_module_ent = java_lang_Module::module_entry_raw(orig_module_obj);
 937   if (orig_module_ent == NULL) {
 938     // These special Module objects are created in Java code. They are not
 939     // defined via Modules::define_module(), so they don't have a ModuleEntry:
 940     //     java.lang.Module::ALL_UNNAMED_MODULE
 941     //     java.lang.Module::EVERYONE_MODULE
 942     //     jdk.internal.loader.ClassLoaders$BootClassLoader::unnamedModule
 943     assert(java_lang_Module::name(orig_module_obj) == NULL, "must be unnamed");
 944     log_info(cds, heap)("Module oop with No ModuleEntry* @[" PTR_FORMAT "]", p2i(orig_module_obj));
 945   } else {
 946     ClassLoaderData* loader_data = orig_module_ent->loader_data();
 947     assert(loader_data->is_builtin_class_loader_data(), "must be");
 948   }
 949 }
 950 
 951 
 952 // (1) If orig_obj has not been archived yet, archive it.
 953 // (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
 954 //     trace all  objects that are reachable from it, and make sure these objects are archived.
 955 // (3) Record the klasses of all orig_obj and all reachable objects.
 956 oop HeapShared::archive_reachable_objects_from(int level,
 957                                                KlassSubGraphInfo* subgraph_info,
 958                                                oop orig_obj,
 959                                                bool is_closed_archive,
 960                                                TRAPS) {
 961   assert(orig_obj != NULL, "must be");
 962   assert(!is_archived_object(orig_obj), "sanity");
 963 
 964   if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
 965     // This object has injected fields that cannot be supported easily, so we disallow them for now.
 966     // If you get an error here, you probably made a change in the JDK library that has added
 967     // these objects that are referenced (directly or indirectly) by static fields.
 968     ResourceMark rm;
 969     log_error(cds, heap)("Cannot archive object of class %s", orig_obj->klass()->external_name());
 970     vm_exit(1);
 971   }
 972 
 973   // java.lang.Class instances cannot be included in an archived object sub-graph. We only support
 974   // them as Klass::_archived_mirror because they need to be specially restored at run time.
 975   //
 976   // If you get an error here, you probably made a change in the JDK library that has added a Class
 977   // object that is referenced (directly or indirectly) by static fields.
 978   if (java_lang_Class::is_instance(orig_obj)) {
 979     log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
 980     vm_exit(1);
 981   }
 982 
 983   oop archived_obj = find_archived_heap_object(orig_obj);
 984   if (java_lang_String::is_instance(orig_obj) && archived_obj != NULL) {
 985     // To save time, don't walk strings that are already archived. They just contain
 986     // pointers to a type array, whose klass doesn't need to be recorded.
 987     return archived_obj;
 988   }
 989 
 990   if (has_been_seen_during_subgraph_recording(orig_obj)) {
 991     // orig_obj has already been archived and traced. Nothing more to do.
 992     return archived_obj;
 993   } else {
 994     set_has_been_seen_during_subgraph_recording(orig_obj);
 995   }
 996 
 997   bool record_klasses_only = (archived_obj != NULL);
 998   if (archived_obj == NULL) {
 999     ++_num_new_archived_objs;
1000     archived_obj = archive_heap_object(orig_obj, THREAD);
1001     if (archived_obj == NULL) {
1002       // Skip archiving the sub-graph referenced from the current entry field.
1003       ResourceMark rm;
1004       log_error(cds, heap)(
1005         "Cannot archive the sub-graph referenced from %s object ("
1006         PTR_FORMAT ") size %d, skipped.",
1007         orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
1008       if (level == 1) {
1009         // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1010         // as the Java code will take care of initializing this field dynamically.
1011         return NULL;
1012       } else {
1013         // We don't know how to handle an object that has been archived, but some of its reachable
1014         // objects cannot be archived. Bail out for now. We might need to fix this in the future if
1015         // we have a real use case.
1016         vm_exit(1);
1017       }
1018     }
1019 
1020     if (java_lang_Module::is_instance(orig_obj)) {
1021       check_module_oop(orig_obj);
1022       java_lang_Module::set_module_entry(archived_obj, NULL);
1023       java_lang_Module::set_loader(archived_obj, NULL);
1024     } else if (java_lang_ClassLoader::is_instance(orig_obj)) {
1025       // class_data will be restored explicitly at run time.
1026       guarantee(orig_obj == SystemDictionary::java_platform_loader() ||
1027                 orig_obj == SystemDictionary::java_system_loader() ||
1028                 java_lang_ClassLoader::loader_data_raw(orig_obj) == NULL, "must be");
1029       java_lang_ClassLoader::release_set_loader_data(archived_obj, NULL);
1030     }
1031   }
1032 
1033   assert(archived_obj != NULL, "must be");
1034   Klass *orig_k = orig_obj->klass();
1035   Klass *relocated_k = archived_obj->klass();
1036   subgraph_info->add_subgraph_object_klass(orig_k, relocated_k);
1037 
1038   WalkOopAndArchiveClosure walker(level, is_closed_archive, record_klasses_only,
1039                                   subgraph_info, orig_obj, archived_obj, THREAD);
1040   orig_obj->oop_iterate(&walker);
1041   if (is_closed_archive && orig_k->is_instance_klass()) {
1042     check_closed_archive_heap_region_object(InstanceKlass::cast(orig_k), THREAD);
1043   }
1044   return archived_obj;
1045 }
1046 
1047 //
1048 // Start from the given static field in a java mirror and archive the
1049 // complete sub-graph of java heap objects that are reached directly
1050 // or indirectly from the starting object by following references.
1051 // Sub-graph archiving restrictions (current):
1052 //
1053 // - All classes of objects in the archived sub-graph (including the
1054 //   entry class) must be boot class only.
1055 // - No java.lang.Class instance (java mirror) can be included inside
1056 //   an archived sub-graph. Mirror can only be the sub-graph entry object.
1057 //
1058 // The Java heap object sub-graph archiving process (see
1059 // WalkOopAndArchiveClosure):
1060 //
1061 // 1) Java object sub-graph archiving starts from a given static field
1062 // within a Class instance (java mirror). If the static field is a
1063 // refererence field and points to a non-null java object, proceed to
1064 // the next step.
1065 //
1066 // 2) Archives the referenced java object. If an archived copy of the
1067 // current object already exists, updates the pointer in the archived
1068 // copy of the referencing object to point to the current archived object.
1069 // Otherwise, proceed to the next step.
1070 //
1071 // 3) Follows all references within the current java object and recursively
1072 // archive the sub-graph of objects starting from each reference.
1073 //
1074 // 4) Updates the pointer in the archived copy of referencing object to
1075 // point to the current archived object.
1076 //
1077 // 5) The Klass of the current java object is added to the list of Klasses
1078 // for loading and initialzing before any object in the archived graph can
1079 // be accessed at runtime.
1080 //
1081 void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
1082                                                              const char* klass_name,
1083                                                              int field_offset,
1084                                                              const char* field_name,
1085                                                              bool is_closed_archive,
1086                                                              TRAPS) {
1087   assert(DumpSharedSpaces, "dump time only");
1088   assert(k->is_shared_boot_class(), "must be boot class");
1089 
1090   oop m = k->java_mirror();
1091 
1092   KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
1093   oop f = m->obj_field(field_offset);
1094 
1095   log_debug(cds, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
1096 
1097   if (!CompressedOops::is_null(f)) {
1098     if (log_is_enabled(Trace, cds, heap)) {
1099       LogTarget(Trace, cds, heap) log;
1100       LogStream out(log);
1101       f->print_on(&out);
1102     }
1103 
1104     oop af = archive_reachable_objects_from(1, subgraph_info, f,
1105                                             is_closed_archive, CHECK);
1106 
1107     if (af == NULL) {
1108       log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
1109                            klass_name, field_name);
1110     } else {
1111       // Note: the field value is not preserved in the archived mirror.
1112       // Record the field as a new subGraph entry point. The recorded
1113       // information is restored from the archive at runtime.
1114       subgraph_info->add_subgraph_entry_field(field_offset, af, is_closed_archive);
1115       log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(af));
1116     }
1117   } else {
1118     // The field contains null, we still need to record the entry point,
1119     // so it can be restored at runtime.
1120     subgraph_info->add_subgraph_entry_field(field_offset, NULL, false);
1121   }
1122 }
1123 
1124 #ifndef PRODUCT
1125 class VerifySharedOopClosure: public BasicOopIterateClosure {
1126  private:
1127   bool _is_archived;
1128 
1129  public:
1130   VerifySharedOopClosure(bool is_archived) : _is_archived(is_archived) {}
1131 
1132   void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
1133   void do_oop(      oop *p) { VerifySharedOopClosure::do_oop_work(p); }
1134 
1135  protected:
1136   template <class T> void do_oop_work(T *p) {
1137     oop obj = RawAccess<>::oop_load(p);
1138     if (!CompressedOops::is_null(obj)) {
1139       HeapShared::verify_reachable_objects_from(obj, _is_archived);
1140     }
1141   }
1142 };
1143 
1144 void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
1145   assert(DumpSharedSpaces, "dump time only");
1146   assert(k->is_shared_boot_class(), "must be boot class");
1147 
1148   oop m = k->java_mirror();
1149   oop f = m->obj_field(field_offset);
1150   if (!CompressedOops::is_null(f)) {
1151     verify_subgraph_from(f);
1152   }
1153 }
1154 
1155 void HeapShared::verify_subgraph_from(oop orig_obj) {
1156   oop archived_obj = find_archived_heap_object(orig_obj);
1157   if (archived_obj == NULL) {
1158     // It's OK for the root of a subgraph to be not archived. See comments in
1159     // archive_reachable_objects_from().
1160     return;
1161   }
1162 
1163   // Verify that all objects reachable from orig_obj are archived.
1164   init_seen_objects_table();
1165   verify_reachable_objects_from(orig_obj, false);
1166   delete_seen_objects_table();
1167 
1168   // Note: we could also verify that all objects reachable from the archived
1169   // copy of orig_obj can only point to archived objects, with:
1170   //      init_seen_objects_table();
1171   //      verify_reachable_objects_from(archived_obj, true);
1172   //      init_seen_objects_table();
1173   // but that's already done in G1HeapVerifier::verify_archive_regions so we
1174   // won't do it here.
1175 }
1176 
1177 void HeapShared::verify_reachable_objects_from(oop obj, bool is_archived) {
1178   _num_total_verifications ++;
1179   if (!has_been_seen_during_subgraph_recording(obj)) {
1180     set_has_been_seen_during_subgraph_recording(obj);
1181 
1182     if (is_archived) {
1183       assert(is_archived_object(obj), "must be");
1184       assert(find_archived_heap_object(obj) == NULL, "must be");
1185     } else {
1186       assert(!is_archived_object(obj), "must be");
1187       assert(find_archived_heap_object(obj) != NULL, "must be");
1188     }
1189 
1190     VerifySharedOopClosure walker(is_archived);
1191     obj->oop_iterate(&walker);
1192   }
1193 }
1194 #endif
1195 
1196 HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = NULL;
1197 int HeapShared::_num_new_walked_objs;
1198 int HeapShared::_num_new_archived_objs;
1199 int HeapShared::_num_old_recorded_klasses;
1200 
1201 int HeapShared::_num_total_subgraph_recordings = 0;
1202 int HeapShared::_num_total_walked_objs = 0;
1203 int HeapShared::_num_total_archived_objs = 0;
1204 int HeapShared::_num_total_recorded_klasses = 0;
1205 int HeapShared::_num_total_verifications = 0;
1206 
1207 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
1208   return _seen_objects_table->get(obj) != NULL;
1209 }
1210 
1211 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
1212   assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
1213   _seen_objects_table->put(obj, true);
1214   ++ _num_new_walked_objs;
1215 }
1216 
1217 void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
1218   log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
1219   init_subgraph_info(k, is_full_module_graph);
1220   init_seen_objects_table();
1221   _num_new_walked_objs = 0;
1222   _num_new_archived_objs = 0;
1223   _num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
1224 }
1225 
1226 void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
1227   int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
1228     _num_old_recorded_klasses;
1229   log_info(cds, heap)("Done recording subgraph(s) for archived fields in %s: "
1230                       "walked %d objs, archived %d new objs, recorded %d classes",
1231                       class_name, _num_new_walked_objs, _num_new_archived_objs,
1232                       num_new_recorded_klasses);
1233 
1234   delete_seen_objects_table();
1235 
1236   _num_total_subgraph_recordings ++;
1237   _num_total_walked_objs      += _num_new_walked_objs;
1238   _num_total_archived_objs    += _num_new_archived_objs;
1239   _num_total_recorded_klasses +=  num_new_recorded_klasses;
1240 }
1241 
1242 class ArchivableStaticFieldFinder: public FieldClosure {
1243   InstanceKlass* _ik;
1244   Symbol* _field_name;
1245   bool _found;
1246   int _offset;
1247 public:
1248   ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
1249     _ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
1250 
1251   virtual void do_field(fieldDescriptor* fd) {
1252     if (fd->name() == _field_name) {
1253       assert(!_found, "fields cannot be overloaded");
1254       assert(is_reference_type(fd->field_type()), "can archive only fields that are references");
1255       _found = true;
1256       _offset = fd->offset();
1257     }
1258   }
1259   bool found()     { return _found;  }
1260   int offset()     { return _offset; }
1261 };
1262 
1263 void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
1264                                             int num, Thread* THREAD) {
1265   for (int i = 0; i < num; i++) {
1266     ArchivableStaticFieldInfo* info = &fields[i];
1267     TempNewSymbol klass_name =  SymbolTable::new_symbol(info->klass_name);
1268     TempNewSymbol field_name =  SymbolTable::new_symbol(info->field_name);
1269 
1270     Klass* k = SystemDictionary::resolve_or_null(klass_name, THREAD);
1271     assert(k != NULL && !HAS_PENDING_EXCEPTION, "class must exist");
1272     InstanceKlass* ik = InstanceKlass::cast(k);
1273     assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
1274            "Only support boot classes");
1275     ik->initialize(THREAD);
1276     guarantee(!HAS_PENDING_EXCEPTION, "exception in initialize");
1277 
1278     ArchivableStaticFieldFinder finder(ik, field_name);
1279     ik->do_local_static_fields(&finder);
1280     assert(finder.found(), "field must exist");
1281 
1282     info->klass = ik;
1283     info->offset = finder.offset();
1284   }
1285 }
1286 
1287 void HeapShared::init_subgraph_entry_fields(Thread* THREAD) {
1288   _dump_time_subgraph_info_table = new (ResourceObj::C_HEAP, mtClass)DumpTimeKlassSubGraphInfoTable();
1289 
1290   init_subgraph_entry_fields(closed_archive_subgraph_entry_fields,
1291                              num_closed_archive_subgraph_entry_fields,
1292                              THREAD);
1293   init_subgraph_entry_fields(open_archive_subgraph_entry_fields,
1294                              num_open_archive_subgraph_entry_fields,
1295                              THREAD);
1296   if (MetaspaceShared::use_full_module_graph()) {
1297     init_subgraph_entry_fields(fmg_open_archive_subgraph_entry_fields,
1298                                num_fmg_open_archive_subgraph_entry_fields,
1299                                THREAD);
1300   }
1301 }
1302 
1303 void HeapShared::init_for_dumping(Thread* THREAD) {
1304   _dumped_interned_strings = new (ResourceObj::C_HEAP, mtClass)DumpedInternedStrings();
1305   init_subgraph_entry_fields(THREAD);
1306 }
1307 
1308 void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
1309                                           int num, bool is_closed_archive,
1310                                           bool is_full_module_graph,
1311                                           Thread* THREAD) {
1312   _num_total_subgraph_recordings = 0;
1313   _num_total_walked_objs = 0;
1314   _num_total_archived_objs = 0;
1315   _num_total_recorded_klasses = 0;
1316   _num_total_verifications = 0;
1317 
1318   // For each class X that has one or more archived fields:
1319   // [1] Dump the subgraph of each archived field
1320   // [2] Create a list of all the class of the objects that can be reached
1321   //     by any of these static fields.
1322   //     At runtime, these classes are initialized before X's archived fields
1323   //     are restored by HeapShared::initialize_from_archived_subgraph().
1324   int i;
1325   for (i = 0; i < num; ) {
1326     ArchivableStaticFieldInfo* info = &fields[i];
1327     const char* klass_name = info->klass_name;
1328     start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
1329 
1330     // If you have specified consecutive fields of the same klass in
1331     // fields[], these will be archived in the same
1332     // {start_recording_subgraph ... done_recording_subgraph} pass to
1333     // save time.
1334     for (; i < num; i++) {
1335       ArchivableStaticFieldInfo* f = &fields[i];
1336       if (f->klass_name != klass_name) {
1337         break;
1338       }
1339 
1340       archive_reachable_objects_from_static_field(f->klass, f->klass_name,
1341                                                   f->offset, f->field_name,
1342                                                   is_closed_archive, CHECK);
1343     }
1344     done_recording_subgraph(info->klass, klass_name);
1345   }
1346 
1347   log_info(cds, heap)("Archived subgraph records in %s archive heap region = %d",
1348                       is_closed_archive ? "closed" : "open",
1349                       _num_total_subgraph_recordings);
1350   log_info(cds, heap)("  Walked %d objects", _num_total_walked_objs);
1351   log_info(cds, heap)("  Archived %d objects", _num_total_archived_objs);
1352   log_info(cds, heap)("  Recorded %d klasses", _num_total_recorded_klasses);
1353 
1354 #ifndef PRODUCT
1355   for (int i = 0; i < num; i++) {
1356     ArchivableStaticFieldInfo* f = &fields[i];
1357     verify_subgraph_from_static_field(f->klass, f->offset);
1358   }
1359   log_info(cds, heap)("  Verified %d references", _num_total_verifications);
1360 #endif
1361 }
1362 
1363 // Not all the strings in the global StringTable are dumped into the archive, because
1364 // some of those strings may be only referenced by classes that are excluded from
1365 // the archive. We need to explicitly mark the strings that are:
1366 //   [1] used by classes that WILL be archived;
1367 //   [2] included in the SharedArchiveConfigFile.
1368 void HeapShared::add_to_dumped_interned_strings(oop string) {
1369   assert_at_safepoint(); // DumpedInternedStrings uses raw oops
1370   bool created;
1371   _dumped_interned_strings->put_if_absent(string, true, &created);
1372 }
1373 
1374 // At dump-time, find the location of all the non-null oop pointers in an archived heap
1375 // region. This way we can quickly relocate all the pointers without using
1376 // BasicOopIterateClosure at runtime.
1377 class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
1378   narrowOop* _start;
1379   BitMap *_oopmap;
1380   int _num_total_oops;
1381   int _num_null_oops;
1382  public:
1383   FindEmbeddedNonNullPointers(narrowOop* start, BitMap* oopmap)
1384     : _start(start), _oopmap(oopmap), _num_total_oops(0),  _num_null_oops(0) {}
1385 
1386   virtual bool should_verify_oops(void) {
1387     return false;
1388   }
1389   virtual void do_oop(narrowOop* p) {
1390     _num_total_oops ++;
1391     narrowOop v = *p;
1392     if (!CompressedOops::is_null(v)) {
1393       size_t idx = p - _start;
1394       _oopmap->set_bit(idx);
1395     } else {
1396       _num_null_oops ++;
1397     }
1398   }
1399   virtual void do_oop(oop *p) {
1400     ShouldNotReachHere();
1401   }
1402   int num_total_oops() const { return _num_total_oops; }
1403   int num_null_oops()  const { return _num_null_oops; }
1404 };
1405 
1406 ResourceBitMap HeapShared::calculate_oopmap(MemRegion region) {
1407   assert(UseCompressedOops, "must be");
1408   size_t num_bits = region.byte_size() / sizeof(narrowOop);
1409   ResourceBitMap oopmap(num_bits);
1410 
1411   HeapWord* p   = region.start();
1412   HeapWord* end = region.end();
1413   FindEmbeddedNonNullPointers finder((narrowOop*)p, &oopmap);
1414 
1415   int num_objs = 0;
1416   while (p < end) {
1417     oop o = (oop)p;
1418     o->oop_iterate(&finder);
1419     p += o->size();
1420     ++ num_objs;
1421   }
1422 
1423   log_info(cds, heap)("calculate_oopmap: objects = %6d, embedded oops = %7d, nulls = %7d",
1424                       num_objs, finder.num_total_oops(), finder.num_null_oops());
1425   return oopmap;
1426 }
1427 
1428 // Patch all the embedded oop pointers inside an archived heap region,
1429 // to be consistent with the runtime oop encoding.
1430 class PatchEmbeddedPointers: public BitMapClosure {
1431   narrowOop* _start;
1432 
1433  public:
1434   PatchEmbeddedPointers(narrowOop* start) : _start(start) {}
1435 
1436   bool do_bit(size_t offset) {
1437     narrowOop* p = _start + offset;
1438     narrowOop v = *p;
1439     assert(!CompressedOops::is_null(v), "null oops should have been filtered out at dump time");
1440     oop o = HeapShared::decode_from_archive(v);
1441     RawAccess<IS_NOT_NULL>::oop_store(p, o);
1442     return true;
1443   }
1444 };
1445 
1446 void HeapShared::patch_archived_heap_embedded_pointers(MemRegion region, address oopmap,
1447                                                        size_t oopmap_size_in_bits) {
1448   BitMapView bm((BitMap::bm_word_t*)oopmap, oopmap_size_in_bits);
1449 
1450 #ifndef PRODUCT
1451   ResourceMark rm;
1452   ResourceBitMap checkBm = calculate_oopmap(region);
1453   assert(bm.is_same(checkBm), "sanity");
1454 #endif
1455 
1456   PatchEmbeddedPointers patcher((narrowOop*)region.start());
1457   bm.iterate(&patcher);
1458 }
1459 
1460 #endif // INCLUDE_CDS_JAVA_HEAP