1 /*
   2  * Copyright (c) 2018, 2022, 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/archiveUtils.hpp"
  28 #include "cds/cdsHeapVerifier.hpp"
  29 #include "cds/filemap.hpp"
  30 #include "cds/heapShared.inline.hpp"
  31 #include "cds/metaspaceShared.hpp"
  32 #include "classfile/classLoaderData.hpp"
  33 #include "classfile/classLoaderDataShared.hpp"
  34 #include "classfile/javaClasses.inline.hpp"
  35 #include "classfile/moduleEntry.hpp"
  36 #include "classfile/stringTable.hpp"
  37 #include "classfile/symbolTable.hpp"
  38 #include "classfile/systemDictionary.hpp"
  39 #include "classfile/systemDictionaryShared.hpp"
  40 #include "classfile/vmClasses.hpp"
  41 #include "classfile/vmSymbols.hpp"
  42 #include "gc/shared/collectedHeap.hpp"
  43 #include "gc/shared/gcLocker.hpp"
  44 #include "gc/shared/gcVMOperations.hpp"
  45 #include "logging/log.hpp"
  46 #include "logging/logStream.hpp"
  47 #include "memory/iterator.inline.hpp"
  48 #include "memory/metadataFactory.hpp"
  49 #include "memory/metaspaceClosure.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.hpp"
  55 #include "oops/oop.inline.hpp"
  56 #include "prims/jvmtiExport.hpp"
  57 #include "runtime/fieldDescriptor.inline.hpp"
  58 #include "runtime/globals_extension.hpp"
  59 #include "runtime/init.hpp"
  60 #include "runtime/java.hpp"
  61 #include "runtime/javaCalls.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 bool HeapShared::_closed_regions_mapped = false;
  72 bool HeapShared::_open_regions_mapped = false;
  73 bool HeapShared::_is_loaded = false;
  74 bool HeapShared::_disable_writing = false;
  75 address   HeapShared::_narrow_oop_base;
  76 int       HeapShared::_narrow_oop_shift;
  77 DumpedInternedStrings *HeapShared::_dumped_interned_strings = NULL;
  78 
  79 // Support for loaded heap.
  80 uintptr_t HeapShared::_loaded_heap_bottom = 0;
  81 uintptr_t HeapShared::_loaded_heap_top = 0;
  82 uintptr_t HeapShared::_dumptime_base_0 = UINTPTR_MAX;
  83 uintptr_t HeapShared::_dumptime_base_1 = UINTPTR_MAX;
  84 uintptr_t HeapShared::_dumptime_base_2 = UINTPTR_MAX;
  85 uintptr_t HeapShared::_dumptime_base_3 = UINTPTR_MAX;
  86 uintptr_t HeapShared::_dumptime_top    = 0;
  87 intx HeapShared::_runtime_offset_0 = 0;
  88 intx HeapShared::_runtime_offset_1 = 0;
  89 intx HeapShared::_runtime_offset_2 = 0;
  90 intx HeapShared::_runtime_offset_3 = 0;
  91 bool HeapShared::_loading_failed = false;
  92 
  93 // Suport for mapped heap (!UseCompressedOops only)
  94 ptrdiff_t HeapShared::_runtime_delta = 0;
  95 
  96 //
  97 // If you add new entries to the following tables, you should know what you're doing!
  98 //
  99 
 100 // Entry fields for shareable subgraphs archived in the closed archive heap
 101 // region. Warning: Objects in the subgraphs should not have reference fields
 102 // assigned at runtime.
 103 static ArchivableStaticFieldInfo closed_archive_subgraph_entry_fields[] = {
 104   {"java/lang/Integer$IntegerCache",              "archivedCache"},
 105   {"java/lang/Long$LongCache",                    "archivedCache"},
 106   {"java/lang/Byte$ByteCache",                    "archivedCache"},
 107   {"java/lang/Short$ShortCache",                  "archivedCache"},
 108   {"java/lang/Character$CharacterCache",          "archivedCache"},
 109   {"java/util/jar/Attributes$Name",               "KNOWN_NAMES"},
 110   {"sun/util/locale/BaseLocale",                  "constantBaseLocales"},
 111 };
 112 // Entry fields for subgraphs archived in the open archive heap region.
 113 static ArchivableStaticFieldInfo open_archive_subgraph_entry_fields[] = {
 114   {"jdk/internal/module/ArchivedModuleGraph",     "archivedModuleGraph"},
 115   {"java/util/ImmutableCollections",              "archivedObjects"},
 116   {"java/lang/ModuleLayer",                       "EMPTY_LAYER"},
 117   {"java/lang/module/Configuration",              "EMPTY_CONFIGURATION"},
 118   {"jdk/internal/math/FDBigInteger",              "archivedCaches"},
 119 };
 120 
 121 // Entry fields for subgraphs archived in the open archive heap region (full module graph).
 122 static ArchivableStaticFieldInfo fmg_open_archive_subgraph_entry_fields[] = {
 123   {"jdk/internal/loader/ArchivedClassLoaders",    "archivedClassLoaders"},
 124   {"jdk/internal/module/ArchivedBootLayer",       "archivedBootLayer"},
 125   {"java/lang/Module$ArchivedData",               "archivedData"},
 126 };
 127 
 128 const static int num_closed_archive_subgraph_entry_fields =
 129   sizeof(closed_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
 130 const static int num_open_archive_subgraph_entry_fields =
 131   sizeof(open_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
 132 const static int num_fmg_open_archive_subgraph_entry_fields =
 133   sizeof(fmg_open_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
 134 
 135 GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = NULL;
 136 OopHandle HeapShared::_roots;
 137 
 138 #ifdef ASSERT
 139 bool HeapShared::is_archived_object_during_dumptime(oop p) {
 140   assert(HeapShared::can_write(), "must be");
 141   assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
 142   return Universe::heap()->is_archived_object(p);
 143 }
 144 #endif
 145 
 146 static bool is_subgraph_root_class_of(ArchivableStaticFieldInfo fields[], int num, InstanceKlass* ik) {
 147   for (int i = 0; i < num; i++) {
 148     if (fields[i].klass == ik) {
 149       return true;
 150     }
 151   }
 152   return false;
 153 }
 154 
 155 bool HeapShared::is_subgraph_root_class(InstanceKlass* ik) {
 156   return is_subgraph_root_class_of(closed_archive_subgraph_entry_fields,
 157                                    num_closed_archive_subgraph_entry_fields, ik) ||
 158          is_subgraph_root_class_of(open_archive_subgraph_entry_fields,
 159                                    num_open_archive_subgraph_entry_fields, ik) ||
 160          is_subgraph_root_class_of(fmg_open_archive_subgraph_entry_fields,
 161                                    num_fmg_open_archive_subgraph_entry_fields, ik);
 162 }
 163 
 164 void HeapShared::fixup_regions() {
 165   FileMapInfo* mapinfo = FileMapInfo::current_info();
 166   if (is_mapped()) {
 167     mapinfo->fixup_mapped_heap_regions();
 168   } else if (_loading_failed) {
 169     fill_failed_loaded_region();
 170   }
 171   if (is_fully_available()) {
 172     if (!MetaspaceShared::use_full_module_graph()) {
 173       // Need to remove all the archived java.lang.Module objects from HeapShared::roots().
 174       ClassLoaderDataShared::clear_archived_oops();
 175     }
 176   }
 177   SystemDictionaryShared::update_archived_mirror_native_pointers();
 178 }
 179 
 180 unsigned HeapShared::oop_hash(oop const& p) {
 181   // We are at a safepoint, so the object won't move. It's OK to use its
 182   // address as the hashcode.
 183   // We can't use p->identity_hash() as it's not available for primitive oops.
 184   assert_at_safepoint();
 185   return (unsigned)(p2i(p) >> LogBytesPerWord);
 186 }
 187 
 188 static void reset_states(oop obj, TRAPS) {
 189   Handle h_obj(THREAD, obj);
 190   InstanceKlass* klass = InstanceKlass::cast(obj->klass());
 191   TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
 192   Symbol* method_sig = vmSymbols::void_method_signature();
 193 
 194   while (klass != NULL) {
 195     Method* method = klass->find_method(method_name, method_sig);
 196     if (method != NULL) {
 197       assert(method->is_private(), "must be");
 198       if (log_is_enabled(Debug, cds)) {
 199         ResourceMark rm(THREAD);
 200         log_debug(cds)("  calling %s", method->name_and_sig_as_C_string());
 201       }
 202       JavaValue result(T_VOID);
 203       JavaCalls::call_special(&result, h_obj, klass,
 204                               method_name, method_sig, CHECK);
 205     }
 206     klass = klass->java_super();
 207   }
 208 }
 209 
 210 void HeapShared::reset_archived_object_states(TRAPS) {
 211   assert(DumpSharedSpaces, "dump-time only");
 212   log_debug(cds)("Resetting platform loader");
 213   reset_states(SystemDictionary::java_platform_loader(), CHECK);
 214   log_debug(cds)("Resetting system loader");
 215   reset_states(SystemDictionary::java_system_loader(), CHECK);
 216 }
 217 
 218 HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = NULL;
 219 oop HeapShared::find_archived_heap_object(oop obj) {
 220   assert(DumpSharedSpaces, "dump-time only");
 221   ArchivedObjectCache* cache = archived_object_cache();
 222   CachedOopInfo* p = cache->get(obj);
 223   if (p != NULL) {
 224     return p->_obj;
 225   } else {
 226     return NULL;
 227   }
 228 }
 229 
 230 int HeapShared::append_root(oop obj) {
 231   assert(DumpSharedSpaces, "dump-time only");
 232 
 233   // No GC should happen since we aren't scanning _pending_roots.
 234   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 235 
 236   if (_pending_roots == NULL) {
 237     _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
 238   }
 239 
 240   return _pending_roots->append(obj);
 241 }
 242 
 243 objArrayOop HeapShared::roots() {
 244   if (DumpSharedSpaces) {
 245     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 246     if (!HeapShared::can_write()) {
 247       return NULL;
 248     }
 249   } else {
 250     assert(UseSharedSpaces, "must be");
 251   }
 252 
 253   objArrayOop roots = (objArrayOop)_roots.resolve();
 254   assert(roots != NULL, "should have been initialized");
 255   return roots;
 256 }
 257 
 258 // Returns an objArray that contains all the roots of the archived objects
 259 oop HeapShared::get_root(int index, bool clear) {
 260   assert(index >= 0, "sanity");
 261   if (DumpSharedSpaces) {
 262     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 263     assert(_pending_roots != NULL, "sanity");
 264     return _pending_roots->at(index);
 265   } else {
 266     assert(UseSharedSpaces, "must be");
 267     assert(!_roots.is_empty(), "must have loaded shared heap");
 268     oop result = roots()->obj_at(index);
 269     if (clear) {
 270       clear_root(index);
 271     }
 272     return result;
 273   }
 274 }
 275 
 276 void HeapShared::clear_root(int index) {
 277   assert(index >= 0, "sanity");
 278   assert(UseSharedSpaces, "must be");
 279   if (is_fully_available()) {
 280     if (log_is_enabled(Debug, cds, heap)) {
 281       oop old = roots()->obj_at(index);
 282       log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
 283     }
 284     roots()->obj_at_put(index, NULL);
 285   }
 286 }
 287 
 288 oop HeapShared::archive_object(oop obj) {
 289   assert(DumpSharedSpaces, "dump-time only");
 290 
 291   oop ao = find_archived_heap_object(obj);
 292   if (ao != NULL) {
 293     // already archived
 294     return ao;
 295   }
 296 
 297   int len = obj->size();
 298   if (G1CollectedHeap::heap()->is_archive_alloc_too_large(len)) {
 299     log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
 300                          p2i(obj), (size_t)obj->size());
 301     return NULL;
 302   }
 303 
 304   oop archived_oop = cast_to_oop(G1CollectedHeap::heap()->archive_mem_allocate(len));
 305   if (archived_oop != NULL) {
 306     Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), cast_from_oop<HeapWord*>(archived_oop), len);
 307     // Reinitialize markword to remove age/marking/locking/etc.
 308     //
 309     // We need to retain the identity_hash, because it may have been used by some hashtables
 310     // in the shared heap. This also has the side effect of pre-initializing the
 311     // identity_hash for all shared objects, so they are less likely to be written
 312     // into during run time, increasing the potential of memory sharing.
 313     if (!(EnableValhalla && obj->mark().is_inline_type())) {
 314       int hash_original = obj->identity_hash();
 315       archived_oop->set_mark(archived_oop->klass()->prototype_header().copy_set_hash(hash_original));
 316       assert(archived_oop->mark().is_unlocked(), "sanity");
 317 
 318       DEBUG_ONLY(int hash_archived = archived_oop->identity_hash());
 319       assert(hash_original == hash_archived, "Different hash codes: original %x, archived %x", hash_original, hash_archived);
 320     }
 321 
 322     ArchivedObjectCache* cache = archived_object_cache();
 323     CachedOopInfo info = make_cached_oop_info(archived_oop);
 324     cache->put(obj, info);
 325     if (log_is_enabled(Debug, cds, heap)) {
 326       ResourceMark rm;
 327       log_debug(cds, heap)("Archived heap object " PTR_FORMAT " ==> " PTR_FORMAT " : %s",
 328                            p2i(obj), p2i(archived_oop), obj->klass()->external_name());
 329     }
 330   } else {
 331     log_error(cds, heap)(
 332       "Cannot allocate space for object " PTR_FORMAT " in archived heap region",
 333       p2i(obj));
 334     vm_direct_exit(-1,
 335       err_msg("Out of memory. Please run with a larger Java heap, current MaxHeapSize = "
 336               SIZE_FORMAT "M", MaxHeapSize/M));
 337   }
 338   return archived_oop;
 339 }
 340 
 341 void HeapShared::archive_klass_objects() {
 342   GrowableArray<Klass*>* klasses = ArchiveBuilder::current()->klasses();
 343   assert(klasses != NULL, "sanity");
 344   for (int i = 0; i < klasses->length(); i++) {
 345     Klass* k = ArchiveBuilder::get_relocated_klass(klasses->at(i));
 346 
 347     // archive mirror object
 348     java_lang_Class::archive_mirror(k);
 349 
 350     // archive the resolved_referenes array
 351     if (k->is_instance_klass()) {
 352       InstanceKlass* ik = InstanceKlass::cast(k);
 353       ik->constants()->archive_resolved_references();
 354     }
 355   }
 356 }
 357 
 358 // -- Handling of Enum objects
 359 // Java Enum classes have synthetic <clinit> methods that look like this
 360 //     enum MyEnum {FOO, BAR}
 361 //     MyEnum::<clinint> {
 362 //        /*static final MyEnum*/ MyEnum::FOO = new MyEnum("FOO");
 363 //        /*static final MyEnum*/ MyEnum::BAR = new MyEnum("BAR");
 364 //     }
 365 //
 366 // If MyEnum::FOO object is referenced by any of the archived subgraphs, we must
 367 // ensure the archived value equals (in object address) to the runtime value of
 368 // MyEnum::FOO.
 369 //
 370 // However, since MyEnum::<clinint> is synthetically generated by javac, there's
 371 // no way of programatically handling this inside the Java code (as you would handle
 372 // ModuleLayer::EMPTY_LAYER, for example).
 373 //
 374 // Instead, we archive all static field of such Enum classes. At runtime,
 375 // HeapShared::initialize_enum_klass() will skip the <clinit> method and pull
 376 // the static fields out of the archived heap.
 377 void HeapShared::check_enum_obj(int level,
 378                                 KlassSubGraphInfo* subgraph_info,
 379                                 oop orig_obj,
 380                                 bool is_closed_archive) {
 381   Klass* k = orig_obj->klass();
 382   Klass* relocated_k = ArchiveBuilder::get_relocated_klass(k);
 383   if (!k->is_instance_klass()) {
 384     return;
 385   }
 386   InstanceKlass* ik = InstanceKlass::cast(k);
 387   if (ik->java_super() == vmClasses::Enum_klass() && !ik->has_archived_enum_objs()) {
 388     ResourceMark rm;
 389     ik->set_has_archived_enum_objs();
 390     relocated_k->set_has_archived_enum_objs();
 391     oop mirror = ik->java_mirror();
 392 
 393     for (JavaFieldStream fs(ik); !fs.done(); fs.next()) {
 394       if (fs.access_flags().is_static()) {
 395         fieldDescriptor& fd = fs.field_descriptor();
 396         if (fd.field_type() != T_OBJECT && fd.field_type() != T_ARRAY) {
 397           guarantee(false, "static field %s::%s must be T_OBJECT or T_ARRAY",
 398                     ik->external_name(), fd.name()->as_C_string());
 399         }
 400         oop oop_field = mirror->obj_field(fd.offset());
 401         if (oop_field == NULL) {
 402           guarantee(false, "static field %s::%s must not be null",
 403                     ik->external_name(), fd.name()->as_C_string());
 404         } else if (oop_field->klass() != ik && oop_field->klass() != ik->array_klass_or_null()) {
 405           guarantee(false, "static field %s::%s is of the wrong type",
 406                     ik->external_name(), fd.name()->as_C_string());
 407         }
 408         oop archived_oop_field = archive_reachable_objects_from(level, subgraph_info, oop_field, is_closed_archive);
 409         int root_index = append_root(archived_oop_field);
 410         log_info(cds, heap)("Archived enum obj @%d %s::%s (" INTPTR_FORMAT " -> " INTPTR_FORMAT ")",
 411                             root_index, ik->external_name(), fd.name()->as_C_string(),
 412                             p2i((oopDesc*)oop_field), p2i((oopDesc*)archived_oop_field));
 413         SystemDictionaryShared::add_enum_klass_static_field(ik, root_index);
 414       }
 415     }
 416   }
 417 }
 418 
 419 // See comments in HeapShared::check_enum_obj()
 420 bool HeapShared::initialize_enum_klass(InstanceKlass* k, TRAPS) {
 421   if (!is_fully_available()) {
 422     return false;
 423   }
 424 
 425   RunTimeClassInfo* info = RunTimeClassInfo::get_for(k);
 426   assert(info != NULL, "sanity");
 427 
 428   if (log_is_enabled(Info, cds, heap)) {
 429     ResourceMark rm;
 430     log_info(cds, heap)("Initializing Enum class: %s", k->external_name());
 431   }
 432 
 433   oop mirror = k->java_mirror();
 434   int i = 0;
 435   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
 436     if (fs.access_flags().is_static()) {
 437       int root_index = info->enum_klass_static_field_root_index_at(i++);
 438       fieldDescriptor& fd = fs.field_descriptor();
 439       assert(fd.field_type() == T_OBJECT || fd.field_type() == T_ARRAY, "must be");
 440       mirror->obj_field_put(fd.offset(), get_root(root_index, /*clear=*/true));
 441     }
 442   }
 443   return true;
 444 }
 445 
 446 void HeapShared::run_full_gc_in_vm_thread() {
 447   if (HeapShared::can_write()) {
 448     // Avoid fragmentation while archiving heap objects.
 449     // We do this inside a safepoint, so that no further allocation can happen after GC
 450     // has finished.
 451     if (GCLocker::is_active()) {
 452       // Just checking for safety ...
 453       // This should not happen during -Xshare:dump. If you see this, probably the Java core lib
 454       // has been modified such that JNI code is executed in some clean up threads after
 455       // we have finished class loading.
 456       log_warning(cds)("GC locker is held, unable to start extra compacting GC. This may produce suboptimal results.");
 457     } else {
 458       log_info(cds)("Run GC ...");
 459       Universe::heap()->collect_as_vm_thread(GCCause::_archive_time_gc);
 460       log_info(cds)("Run GC done");
 461     }
 462   }
 463 }
 464 
 465 void HeapShared::archive_objects(GrowableArray<MemRegion>* closed_regions,
 466                                  GrowableArray<MemRegion>* open_regions) {
 467 
 468   G1HeapVerifier::verify_ready_for_archiving();
 469 
 470   {
 471     NoSafepointVerifier nsv;
 472 
 473     // Cache for recording where the archived objects are copied to
 474     create_archived_object_cache();
 475 
 476     log_info(cds)("Heap range = [" PTR_FORMAT " - "  PTR_FORMAT "]",
 477                    UseCompressedOops ? p2i(CompressedOops::begin()) :
 478                                        p2i((address)G1CollectedHeap::heap()->reserved().start()),
 479                    UseCompressedOops ? p2i(CompressedOops::end()) :
 480                                        p2i((address)G1CollectedHeap::heap()->reserved().end()));
 481     log_info(cds)("Dumping objects to closed archive heap region ...");
 482     copy_closed_objects(closed_regions);
 483 
 484     log_info(cds)("Dumping objects to open archive heap region ...");
 485     copy_open_objects(open_regions);
 486 
 487     CDSHeapVerifier::verify();
 488     destroy_archived_object_cache();
 489   }
 490 
 491   G1HeapVerifier::verify_archive_regions();
 492 }
 493 
 494 void HeapShared::copy_closed_objects(GrowableArray<MemRegion>* closed_regions) {
 495   assert(HeapShared::can_write(), "must be");
 496 
 497   G1CollectedHeap::heap()->begin_archive_alloc_range();
 498 
 499   // Archive interned string objects
 500   StringTable::write_to_archive(_dumped_interned_strings);
 501 
 502   archive_object_subgraphs(closed_archive_subgraph_entry_fields,
 503                            num_closed_archive_subgraph_entry_fields,
 504                            true /* is_closed_archive */,
 505                            false /* is_full_module_graph */);
 506 
 507   G1CollectedHeap::heap()->end_archive_alloc_range(closed_regions,
 508                                                    os::vm_allocation_granularity());
 509 }
 510 
 511 void HeapShared::copy_open_objects(GrowableArray<MemRegion>* open_regions) {
 512   assert(HeapShared::can_write(), "must be");
 513 
 514   G1CollectedHeap::heap()->begin_archive_alloc_range(true /* open */);
 515 
 516   java_lang_Class::archive_basic_type_mirrors();
 517 
 518   archive_klass_objects();
 519 
 520   archive_object_subgraphs(open_archive_subgraph_entry_fields,
 521                            num_open_archive_subgraph_entry_fields,
 522                            false /* is_closed_archive */,
 523                            false /* is_full_module_graph */);
 524   if (MetaspaceShared::use_full_module_graph()) {
 525     archive_object_subgraphs(fmg_open_archive_subgraph_entry_fields,
 526                              num_fmg_open_archive_subgraph_entry_fields,
 527                              false /* is_closed_archive */,
 528                              true /* is_full_module_graph */);
 529     ClassLoaderDataShared::init_archived_oops();
 530   }
 531 
 532   copy_roots();
 533 
 534   G1CollectedHeap::heap()->end_archive_alloc_range(open_regions,
 535                                                    os::vm_allocation_granularity());
 536 }
 537 
 538 // Copy _pending_archive_roots into an objArray
 539 void HeapShared::copy_roots() {
 540   int length = _pending_roots != NULL ? _pending_roots->length() : 0;
 541   size_t size = objArrayOopDesc::object_size(length);
 542   Klass* k = Universe::objectArrayKlassObj(); // already relocated to point to archived klass
 543   HeapWord* mem = G1CollectedHeap::heap()->archive_mem_allocate(size);
 544 
 545   memset(mem, 0, size * BytesPerWord);
 546   {
 547     // This is copied from MemAllocator::finish
 548     oopDesc::set_mark(mem, k->prototype_header());
 549     oopDesc::release_set_klass(mem, k);
 550   }
 551   {
 552     // This is copied from ObjArrayAllocator::initialize
 553     arrayOopDesc::set_length(mem, length);
 554   }
 555 
 556   _roots = OopHandle(Universe::vm_global(), cast_to_oop(mem));
 557   for (int i = 0; i < length; i++) {
 558     roots()->obj_at_put(i, _pending_roots->at(i));
 559   }
 560   log_info(cds)("archived obj roots[%d] = " SIZE_FORMAT " words, klass = %p, obj = %p", length, size, k, mem);
 561 }
 562 
 563 void HeapShared::init_narrow_oop_decoding(address base, int shift) {
 564   _narrow_oop_base = base;
 565   _narrow_oop_shift = shift;
 566 }
 567 
 568 //
 569 // Subgraph archiving support
 570 //
 571 HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = NULL;
 572 HeapShared::RunTimeKlassSubGraphInfoTable   HeapShared::_run_time_subgraph_info_table;
 573 
 574 // Get the subgraph_info for Klass k. A new subgraph_info is created if
 575 // there is no existing one for k. The subgraph_info records the relocated
 576 // Klass* of the original k.
 577 KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
 578   assert(DumpSharedSpaces, "dump time only");
 579   bool created;
 580   Klass* relocated_k = ArchiveBuilder::get_relocated_klass(k);
 581   KlassSubGraphInfo* info =
 582     _dump_time_subgraph_info_table->put_if_absent(k, KlassSubGraphInfo(relocated_k, is_full_module_graph),
 583                                                   &created);
 584   assert(created, "must not initialize twice");
 585   return info;
 586 }
 587 
 588 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
 589   assert(DumpSharedSpaces, "dump time only");
 590   KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
 591   assert(info != NULL, "must have been initialized");
 592   return info;
 593 }
 594 
 595 // Add an entry field to the current KlassSubGraphInfo.
 596 void KlassSubGraphInfo::add_subgraph_entry_field(
 597       int static_field_offset, oop v, bool is_closed_archive) {
 598   assert(DumpSharedSpaces, "dump time only");
 599   if (_subgraph_entry_fields == NULL) {
 600     _subgraph_entry_fields =
 601       new(ResourceObj::C_HEAP, mtClass) GrowableArray<int>(10, mtClass);
 602   }
 603   _subgraph_entry_fields->append(static_field_offset);
 604   _subgraph_entry_fields->append(HeapShared::append_root(v));
 605 }
 606 
 607 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
 608 // Only objects of boot classes can be included in sub-graph.
 609 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
 610   assert(DumpSharedSpaces, "dump time only");
 611   Klass* relocated_k = ArchiveBuilder::get_relocated_klass(orig_k);
 612 
 613   if (_subgraph_object_klasses == NULL) {
 614     _subgraph_object_klasses =
 615       new(ResourceObj::C_HEAP, mtClass) GrowableArray<Klass*>(50, mtClass);
 616   }
 617 
 618   assert(ArchiveBuilder::current()->is_in_buffer_space(relocated_k), "must be a shared class");
 619 
 620   if (_k == relocated_k) {
 621     // Don't add the Klass containing the sub-graph to it's own klass
 622     // initialization list.
 623     return;
 624   }
 625 
 626   if (relocated_k->is_instance_klass()) {
 627     assert(InstanceKlass::cast(relocated_k)->is_shared_boot_class(),
 628           "must be boot class");
 629     // vmClasses::xxx_klass() are not updated, need to check
 630     // the original Klass*
 631     if (orig_k == vmClasses::String_klass() ||
 632         orig_k == vmClasses::Object_klass()) {
 633       // Initialized early during VM initialization. No need to be added
 634       // to the sub-graph object class list.
 635       return;
 636     }
 637   } else if (relocated_k->is_objArray_klass()) {
 638     Klass* abk = ObjArrayKlass::cast(relocated_k)->bottom_klass();
 639     if (abk->is_instance_klass()) {
 640       assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
 641             "must be boot class");
 642     }
 643     if (relocated_k == Universe::objectArrayKlassObj()) {
 644       // Initialized early during Universe::genesis. No need to be added
 645       // to the list.
 646       return;
 647     }
 648   } else {
 649     assert(relocated_k->is_typeArray_klass(), "must be");
 650     // Primitive type arrays are created early during Universe::genesis.
 651     return;
 652   }
 653 
 654   if (log_is_enabled(Debug, cds, heap)) {
 655     if (!_subgraph_object_klasses->contains(relocated_k)) {
 656       ResourceMark rm;
 657       log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
 658     }
 659   }
 660 
 661   _subgraph_object_klasses->append_if_missing(relocated_k);
 662   _has_non_early_klasses |= is_non_early_klass(orig_k);
 663 }
 664 
 665 bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
 666   if (k->is_objArray_klass()) {
 667     k = ObjArrayKlass::cast(k)->bottom_klass();
 668   }
 669   if (k->is_instance_klass()) {
 670     if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
 671       ResourceMark rm;
 672       log_info(cds, heap)("non-early: %s", k->external_name());
 673       return true;
 674     } else {
 675       return false;
 676     }
 677   } else {
 678     return false;
 679   }
 680 }
 681 
 682 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
 683 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
 684   _k = info->klass();
 685   _entry_field_records = NULL;
 686   _subgraph_object_klasses = NULL;
 687   _is_full_module_graph = info->is_full_module_graph();
 688 
 689   if (_is_full_module_graph) {
 690     // Consider all classes referenced by the full module graph as early -- we will be
 691     // allocating objects of these classes during JVMTI early phase, so they cannot
 692     // be processed by (non-early) JVMTI ClassFileLoadHook
 693     _has_non_early_klasses = false;
 694   } else {
 695     _has_non_early_klasses = info->has_non_early_klasses();
 696   }
 697 
 698   if (_has_non_early_klasses) {
 699     ResourceMark rm;
 700     log_info(cds, heap)(
 701           "Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
 702           _k->external_name());
 703   }
 704 
 705   // populate the entry fields
 706   GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
 707   if (entry_fields != NULL) {
 708     int num_entry_fields = entry_fields->length();
 709     assert(num_entry_fields % 2 == 0, "sanity");
 710     _entry_field_records =
 711       ArchiveBuilder::new_ro_array<int>(num_entry_fields);
 712     for (int i = 0 ; i < num_entry_fields; i++) {
 713       _entry_field_records->at_put(i, entry_fields->at(i));
 714     }
 715   }
 716 
 717   // the Klasses of the objects in the sub-graphs
 718   GrowableArray<Klass*>* subgraph_object_klasses = info->subgraph_object_klasses();
 719   if (subgraph_object_klasses != NULL) {
 720     int num_subgraphs_klasses = subgraph_object_klasses->length();
 721     _subgraph_object_klasses =
 722       ArchiveBuilder::new_ro_array<Klass*>(num_subgraphs_klasses);
 723     for (int i = 0; i < num_subgraphs_klasses; i++) {
 724       Klass* subgraph_k = subgraph_object_klasses->at(i);
 725       if (log_is_enabled(Info, cds, heap)) {
 726         ResourceMark rm;
 727         log_info(cds, heap)(
 728           "Archived object klass %s (%2d) => %s",
 729           _k->external_name(), i, subgraph_k->external_name());
 730       }
 731       _subgraph_object_klasses->at_put(i, subgraph_k);
 732       ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(i));
 733     }
 734   }
 735 
 736   ArchivePtrMarker::mark_pointer(&_k);
 737   ArchivePtrMarker::mark_pointer(&_entry_field_records);
 738   ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
 739 }
 740 
 741 struct CopyKlassSubGraphInfoToArchive : StackObj {
 742   CompactHashtableWriter* _writer;
 743   CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
 744 
 745   bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
 746     if (info.subgraph_object_klasses() != NULL || info.subgraph_entry_fields() != NULL) {
 747       ArchivedKlassSubGraphInfoRecord* record =
 748         (ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
 749       record->init(&info);
 750 
 751       Klass* relocated_k = ArchiveBuilder::get_relocated_klass(klass);
 752       unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary((address)relocated_k);
 753       u4 delta = ArchiveBuilder::current()->any_to_offset_u4(record);
 754       _writer->add(hash, delta);
 755     }
 756     return true; // keep on iterating
 757   }
 758 };
 759 
 760 // Build the records of archived subgraph infos, which include:
 761 // - Entry points to all subgraphs from the containing class mirror. The entry
 762 //   points are static fields in the mirror. For each entry point, the field
 763 //   offset, value and is_closed_archive flag are recorded in the sub-graph
 764 //   info. The value is stored back to the corresponding field at runtime.
 765 // - A list of klasses that need to be loaded/initialized before archived
 766 //   java object sub-graph can be accessed at runtime.
 767 void HeapShared::write_subgraph_info_table() {
 768   // Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
 769   DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
 770   CompactHashtableStats stats;
 771 
 772   _run_time_subgraph_info_table.reset();
 773 
 774   CompactHashtableWriter writer(d_table->_count, &stats);
 775   CopyKlassSubGraphInfoToArchive copy(&writer);
 776   d_table->iterate(&copy);
 777   writer.dump(&_run_time_subgraph_info_table, "subgraphs");
 778 }
 779 
 780 void HeapShared::serialize(SerializeClosure* soc) {
 781   oop roots_oop = NULL;
 782 
 783   if (soc->reading()) {
 784     soc->do_oop(&roots_oop); // read from archive
 785     assert(oopDesc::is_oop_or_null(roots_oop), "is oop");
 786     // Create an OopHandle only if we have actually mapped or loaded the roots
 787     if (roots_oop != NULL) {
 788       assert(HeapShared::is_fully_available(), "must be");
 789       _roots = OopHandle(Universe::vm_global(), roots_oop);
 790     }
 791   } else {
 792     // writing
 793     roots_oop = roots();
 794     soc->do_oop(&roots_oop); // write to archive
 795   }
 796 
 797   _run_time_subgraph_info_table.serialize_header(soc);
 798 }
 799 
 800 static void verify_the_heap(Klass* k, const char* which) {
 801   if (VerifyArchivedFields > 0) {
 802     ResourceMark rm;
 803     log_info(cds, heap)("Verify heap %s initializing static field(s) in %s",
 804                         which, k->external_name());
 805 
 806     VM_Verify verify_op;
 807     VMThread::execute(&verify_op);
 808 
 809     if (VerifyArchivedFields > 1 && is_init_completed()) {
 810       // At this time, the oop->klass() of some archived objects in the heap may not
 811       // have been loaded into the system dictionary yet. Nevertheless, oop->klass() should
 812       // have enough information (object size, oop maps, etc) so that a GC can be safely
 813       // performed.
 814       //
 815       // -XX:VerifyArchivedFields=2 force a GC to happen in such an early stage
 816       // to check for GC safety.
 817       log_info(cds, heap)("Trigger GC %s initializing static field(s) in %s",
 818                           which, k->external_name());
 819       FlagSetting fs1(VerifyBeforeGC, true);
 820       FlagSetting fs2(VerifyDuringGC, true);
 821       FlagSetting fs3(VerifyAfterGC,  true);
 822       Universe::heap()->collect(GCCause::_java_lang_system_gc);
 823     }
 824   }
 825 }
 826 
 827 // Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
 828 // have a valid klass. I.e., oopDesc::klass() must have already been resolved.
 829 //
 830 // Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
 831 // ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
 832 // this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
 833 void HeapShared::resolve_classes(JavaThread* THREAD) {
 834   if (!is_fully_available()) {
 835     return; // nothing to do
 836   }
 837   resolve_classes_for_subgraphs(closed_archive_subgraph_entry_fields,
 838                                 num_closed_archive_subgraph_entry_fields,
 839                                 THREAD);
 840   resolve_classes_for_subgraphs(open_archive_subgraph_entry_fields,
 841                                 num_open_archive_subgraph_entry_fields,
 842                                 THREAD);
 843   resolve_classes_for_subgraphs(fmg_open_archive_subgraph_entry_fields,
 844                                 num_fmg_open_archive_subgraph_entry_fields,
 845                                 THREAD);
 846 }
 847 
 848 void HeapShared::resolve_classes_for_subgraphs(ArchivableStaticFieldInfo fields[],
 849                                                int num, JavaThread* THREAD) {
 850   for (int i = 0; i < num; i++) {
 851     ArchivableStaticFieldInfo* info = &fields[i];
 852     TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
 853     InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
 854     assert(k != NULL && k->is_shared_boot_class(), "sanity");
 855     resolve_classes_for_subgraph_of(k, THREAD);
 856   }
 857 }
 858 
 859 void HeapShared::resolve_classes_for_subgraph_of(Klass* k, JavaThread* THREAD) {
 860   ExceptionMark em(THREAD);
 861   const ArchivedKlassSubGraphInfoRecord* record =
 862    resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
 863   if (HAS_PENDING_EXCEPTION) {
 864    CLEAR_PENDING_EXCEPTION;
 865   }
 866   if (record == NULL) {
 867    clear_archived_roots_of(k);
 868   }
 869 }
 870 
 871 void HeapShared::initialize_from_archived_subgraph(Klass* k, JavaThread* THREAD) {
 872   if (!is_fully_available()) {
 873     return; // nothing to do
 874   }
 875 
 876   ExceptionMark em(THREAD);
 877   const ArchivedKlassSubGraphInfoRecord* record =
 878     resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
 879 
 880   if (HAS_PENDING_EXCEPTION) {
 881     CLEAR_PENDING_EXCEPTION;
 882     // None of the field value will be set if there was an exception when initializing the classes.
 883     // The java code will not see any of the archived objects in the
 884     // subgraphs referenced from k in this case.
 885     return;
 886   }
 887 
 888   if (record != NULL) {
 889     init_archived_fields_for(k, record);
 890   }
 891 }
 892 
 893 const ArchivedKlassSubGraphInfoRecord*
 894 HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
 895   assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
 896 
 897   if (!k->is_shared()) {
 898     return NULL;
 899   }
 900   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
 901   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 902 
 903   // Initialize from archived data. Currently this is done only
 904   // during VM initialization time. No lock is needed.
 905   if (record != NULL) {
 906     if (record->is_full_module_graph() && !MetaspaceShared::use_full_module_graph()) {
 907       if (log_is_enabled(Info, cds, heap)) {
 908         ResourceMark rm(THREAD);
 909         log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
 910                             k->external_name());
 911       }
 912       return NULL;
 913     }
 914 
 915     if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
 916       if (log_is_enabled(Info, cds, heap)) {
 917         ResourceMark rm(THREAD);
 918         log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
 919                             k->external_name());
 920       }
 921       return NULL;
 922     }
 923 
 924     resolve_or_init(k, do_init, CHECK_NULL);
 925 
 926     // Load/link/initialize the klasses of the objects in the subgraph.
 927     // NULL class loader is used.
 928     Array<Klass*>* klasses = record->subgraph_object_klasses();
 929     if (klasses != NULL) {
 930       for (int i = 0; i < klasses->length(); i++) {
 931         Klass* klass = klasses->at(i);
 932         if (!klass->is_shared()) {
 933           return NULL;
 934         }
 935         resolve_or_init(klass, do_init, CHECK_NULL);
 936       }
 937     }
 938   }
 939 
 940   return record;
 941 }
 942 
 943 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
 944   if (!do_init) {
 945     if (k->class_loader_data() == NULL) {
 946       Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
 947       assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
 948     }
 949   } else {
 950     assert(k->class_loader_data() != NULL, "must have been resolved by HeapShared::resolve_classes");
 951     if (k->is_instance_klass()) {
 952       InstanceKlass* ik = InstanceKlass::cast(k);
 953       ik->initialize(CHECK);
 954     } else if (k->is_objArray_klass()) {
 955       ObjArrayKlass* oak = ObjArrayKlass::cast(k);
 956       oak->initialize(CHECK);
 957     }
 958   }
 959 }
 960 
 961 void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record) {
 962   verify_the_heap(k, "before");
 963 
 964   // Load the subgraph entry fields from the record and store them back to
 965   // the corresponding fields within the mirror.
 966   oop m = k->java_mirror();
 967   Array<int>* entry_field_records = record->entry_field_records();
 968   if (entry_field_records != NULL) {
 969     int efr_len = entry_field_records->length();
 970     assert(efr_len % 2 == 0, "sanity");
 971     for (int i = 0; i < efr_len; i += 2) {
 972       int field_offset = entry_field_records->at(i);
 973       int root_index = entry_field_records->at(i+1);
 974       oop v = get_root(root_index, /*clear=*/true);
 975       m->obj_field_put(field_offset, v);
 976       log_debug(cds, heap)("  " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
 977     }
 978 
 979     // Done. Java code can see the archived sub-graphs referenced from k's
 980     // mirror after this point.
 981     if (log_is_enabled(Info, cds, heap)) {
 982       ResourceMark rm;
 983       log_info(cds, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s",
 984                           k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "");
 985     }
 986   }
 987 
 988   verify_the_heap(k, "after ");
 989 }
 990 
 991 void HeapShared::clear_archived_roots_of(Klass* k) {
 992   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
 993   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 994   if (record != NULL) {
 995     Array<int>* entry_field_records = record->entry_field_records();
 996     if (entry_field_records != NULL) {
 997       int efr_len = entry_field_records->length();
 998       assert(efr_len % 2 == 0, "sanity");
 999       for (int i = 0; i < efr_len; i += 2) {
1000         int root_index = entry_field_records->at(i+1);
1001         clear_root(root_index);
1002       }
1003     }
1004   }
1005 }
1006 
1007 class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
1008   int _level;
1009   bool _is_closed_archive;
1010   bool _record_klasses_only;
1011   KlassSubGraphInfo* _subgraph_info;
1012   oop _orig_referencing_obj;
1013   oop _archived_referencing_obj;
1014 
1015   // The following are for maintaining a stack for determining
1016   // CachedOopInfo::_referrer
1017   static WalkOopAndArchiveClosure* _current;
1018   WalkOopAndArchiveClosure* _last;
1019  public:
1020   WalkOopAndArchiveClosure(int level,
1021                            bool is_closed_archive,
1022                            bool record_klasses_only,
1023                            KlassSubGraphInfo* subgraph_info,
1024                            oop orig, oop archived) :
1025     _level(level), _is_closed_archive(is_closed_archive),
1026     _record_klasses_only(record_klasses_only),
1027     _subgraph_info(subgraph_info),
1028     _orig_referencing_obj(orig), _archived_referencing_obj(archived) {
1029     _last = _current;
1030     _current = this;
1031   }
1032   ~WalkOopAndArchiveClosure() {
1033     _current = _last;
1034   }
1035   void do_oop(narrowOop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
1036   void do_oop(      oop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
1037 
1038  protected:
1039   template <class T> void do_oop_work(T *p) {
1040     oop obj = RawAccess<>::oop_load(p);
1041     if (!CompressedOops::is_null(obj)) {
1042       assert(!HeapShared::is_archived_object_during_dumptime(obj),
1043              "original objects must not point to archived objects");
1044 
1045       size_t field_delta = pointer_delta(p, _orig_referencing_obj, sizeof(char));
1046       T* new_p = (T*)(cast_from_oop<address>(_archived_referencing_obj) + field_delta);
1047 
1048       if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
1049         ResourceMark rm;
1050         log_debug(cds, heap)("(%d) %s[" SIZE_FORMAT "] ==> " PTR_FORMAT " size " SIZE_FORMAT " %s", _level,
1051                              _orig_referencing_obj->klass()->external_name(), field_delta,
1052                              p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
1053         LogTarget(Trace, cds, heap) log;
1054         LogStream out(log);
1055         obj->print_on(&out);
1056       }
1057 
1058       oop archived = HeapShared::archive_reachable_objects_from(
1059           _level + 1, _subgraph_info, obj, _is_closed_archive);
1060       assert(archived != NULL, "VM should have exited with unarchivable objects for _level > 1");
1061       assert(HeapShared::is_archived_object_during_dumptime(archived), "must be");
1062 
1063       if (!_record_klasses_only) {
1064         // Update the reference in the archived copy of the referencing object.
1065         log_debug(cds, heap)("(%d) updating oop @[" PTR_FORMAT "] " PTR_FORMAT " ==> " PTR_FORMAT,
1066                              _level, p2i(new_p), p2i(obj), p2i(archived));
1067         RawAccess<IS_NOT_NULL>::oop_store(new_p, archived);
1068       }
1069     }
1070   }
1071 
1072  public:
1073   static WalkOopAndArchiveClosure* current()  { return _current;              }
1074   oop orig_referencing_obj()                  { return _orig_referencing_obj; }
1075   KlassSubGraphInfo* subgraph_info()          { return _subgraph_info;        }
1076 };
1077 
1078 WalkOopAndArchiveClosure* WalkOopAndArchiveClosure::_current = NULL;
1079 
1080 HeapShared::CachedOopInfo HeapShared::make_cached_oop_info(oop orig_obj) {
1081   CachedOopInfo info;
1082   WalkOopAndArchiveClosure* walker = WalkOopAndArchiveClosure::current();
1083 
1084   info._subgraph_info = (walker == NULL) ? NULL : walker->subgraph_info();
1085   info._referrer = (walker == NULL) ? NULL : walker->orig_referencing_obj();
1086   info._obj = orig_obj;
1087 
1088   return info;
1089 }
1090 
1091 void HeapShared::check_closed_region_object(InstanceKlass* k) {
1092   // Check fields in the object
1093   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
1094     if (!fs.access_flags().is_static()) {
1095       BasicType ft = fs.field_descriptor().field_type();
1096       if (!fs.access_flags().is_final() && is_reference_type(ft)) {
1097         ResourceMark rm;
1098         log_warning(cds, heap)(
1099           "Please check reference field in %s instance in closed archive heap region: %s %s",
1100           k->external_name(), (fs.name())->as_C_string(),
1101           (fs.signature())->as_C_string());
1102       }
1103     }
1104   }
1105 }
1106 
1107 void HeapShared::check_module_oop(oop orig_module_obj) {
1108   assert(DumpSharedSpaces, "must be");
1109   assert(java_lang_Module::is_instance(orig_module_obj), "must be");
1110   ModuleEntry* orig_module_ent = java_lang_Module::module_entry_raw(orig_module_obj);
1111   if (orig_module_ent == NULL) {
1112     // These special Module objects are created in Java code. They are not
1113     // defined via Modules::define_module(), so they don't have a ModuleEntry:
1114     //     java.lang.Module::ALL_UNNAMED_MODULE
1115     //     java.lang.Module::EVERYONE_MODULE
1116     //     jdk.internal.loader.ClassLoaders$BootClassLoader::unnamedModule
1117     assert(java_lang_Module::name(orig_module_obj) == NULL, "must be unnamed");
1118     log_info(cds, heap)("Module oop with No ModuleEntry* @[" PTR_FORMAT "]", p2i(orig_module_obj));
1119   } else {
1120     ClassLoaderData* loader_data = orig_module_ent->loader_data();
1121     assert(loader_data->is_builtin_class_loader_data(), "must be");
1122   }
1123 }
1124 
1125 
1126 // (1) If orig_obj has not been archived yet, archive it.
1127 // (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
1128 //     trace all  objects that are reachable from it, and make sure these objects are archived.
1129 // (3) Record the klasses of all orig_obj and all reachable objects.
1130 oop HeapShared::archive_reachable_objects_from(int level,
1131                                                KlassSubGraphInfo* subgraph_info,
1132                                                oop orig_obj,
1133                                                bool is_closed_archive) {
1134   assert(orig_obj != NULL, "must be");
1135   assert(!is_archived_object_during_dumptime(orig_obj), "sanity");
1136 
1137   if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
1138     // This object has injected fields that cannot be supported easily, so we disallow them for now.
1139     // If you get an error here, you probably made a change in the JDK library that has added
1140     // these objects that are referenced (directly or indirectly) by static fields.
1141     ResourceMark rm;
1142     log_error(cds, heap)("Cannot archive object of class %s", orig_obj->klass()->external_name());
1143     vm_direct_exit(1);
1144   }
1145 
1146   // java.lang.Class instances cannot be included in an archived object sub-graph. We only support
1147   // them as Klass::_archived_mirror because they need to be specially restored at run time.
1148   //
1149   // If you get an error here, you probably made a change in the JDK library that has added a Class
1150   // object that is referenced (directly or indirectly) by static fields.
1151   if (java_lang_Class::is_instance(orig_obj)) {
1152     log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
1153     vm_direct_exit(1);
1154   }
1155 
1156   oop archived_obj = find_archived_heap_object(orig_obj);
1157   if (java_lang_String::is_instance(orig_obj) && archived_obj != NULL) {
1158     // To save time, don't walk strings that are already archived. They just contain
1159     // pointers to a type array, whose klass doesn't need to be recorded.
1160     return archived_obj;
1161   }
1162 
1163   if (has_been_seen_during_subgraph_recording(orig_obj)) {
1164     // orig_obj has already been archived and traced. Nothing more to do.
1165     return archived_obj;
1166   } else {
1167     set_has_been_seen_during_subgraph_recording(orig_obj);
1168   }
1169 
1170   bool record_klasses_only = (archived_obj != NULL);
1171   if (archived_obj == NULL) {
1172     ++_num_new_archived_objs;
1173     archived_obj = archive_object(orig_obj);
1174     if (archived_obj == NULL) {
1175       // Skip archiving the sub-graph referenced from the current entry field.
1176       ResourceMark rm;
1177       log_error(cds, heap)(
1178         "Cannot archive the sub-graph referenced from %s object ("
1179         PTR_FORMAT ") size " SIZE_FORMAT ", skipped.",
1180         orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
1181       if (level == 1) {
1182         // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1183         // as the Java code will take care of initializing this field dynamically.
1184         return NULL;
1185       } else {
1186         // We don't know how to handle an object that has been archived, but some of its reachable
1187         // objects cannot be archived. Bail out for now. We might need to fix this in the future if
1188         // we have a real use case.
1189         vm_direct_exit(1);
1190       }
1191     }
1192 
1193     if (java_lang_Module::is_instance(orig_obj)) {
1194       check_module_oop(orig_obj);
1195       java_lang_Module::set_module_entry(archived_obj, NULL);
1196       java_lang_Module::set_loader(archived_obj, NULL);
1197     } else if (java_lang_ClassLoader::is_instance(orig_obj)) {
1198       // class_data will be restored explicitly at run time.
1199       guarantee(orig_obj == SystemDictionary::java_platform_loader() ||
1200                 orig_obj == SystemDictionary::java_system_loader() ||
1201                 java_lang_ClassLoader::loader_data(orig_obj) == NULL, "must be");
1202       java_lang_ClassLoader::release_set_loader_data(archived_obj, NULL);
1203     }
1204   }
1205 
1206   assert(archived_obj != NULL, "must be");
1207   Klass *orig_k = orig_obj->klass();
1208   subgraph_info->add_subgraph_object_klass(orig_k);
1209 
1210   WalkOopAndArchiveClosure walker(level, is_closed_archive, record_klasses_only,
1211                                   subgraph_info, orig_obj, archived_obj);
1212   orig_obj->oop_iterate(&walker);
1213   if (is_closed_archive && orig_k->is_instance_klass()) {
1214     check_closed_region_object(InstanceKlass::cast(orig_k));
1215   }
1216 
1217   check_enum_obj(level + 1, subgraph_info, orig_obj, is_closed_archive);
1218   return archived_obj;
1219 }
1220 
1221 //
1222 // Start from the given static field in a java mirror and archive the
1223 // complete sub-graph of java heap objects that are reached directly
1224 // or indirectly from the starting object by following references.
1225 // Sub-graph archiving restrictions (current):
1226 //
1227 // - All classes of objects in the archived sub-graph (including the
1228 //   entry class) must be boot class only.
1229 // - No java.lang.Class instance (java mirror) can be included inside
1230 //   an archived sub-graph. Mirror can only be the sub-graph entry object.
1231 //
1232 // The Java heap object sub-graph archiving process (see
1233 // WalkOopAndArchiveClosure):
1234 //
1235 // 1) Java object sub-graph archiving starts from a given static field
1236 // within a Class instance (java mirror). If the static field is a
1237 // refererence field and points to a non-null java object, proceed to
1238 // the next step.
1239 //
1240 // 2) Archives the referenced java object. If an archived copy of the
1241 // current object already exists, updates the pointer in the archived
1242 // copy of the referencing object to point to the current archived object.
1243 // Otherwise, proceed to the next step.
1244 //
1245 // 3) Follows all references within the current java object and recursively
1246 // archive the sub-graph of objects starting from each reference.
1247 //
1248 // 4) Updates the pointer in the archived copy of referencing object to
1249 // point to the current archived object.
1250 //
1251 // 5) The Klass of the current java object is added to the list of Klasses
1252 // for loading and initialzing before any object in the archived graph can
1253 // be accessed at runtime.
1254 //
1255 void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
1256                                                              const char* klass_name,
1257                                                              int field_offset,
1258                                                              const char* field_name,
1259                                                              bool is_closed_archive) {
1260   assert(DumpSharedSpaces, "dump time only");
1261   assert(k->is_shared_boot_class(), "must be boot class");
1262 
1263   oop m = k->java_mirror();
1264 
1265   KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
1266   oop f = m->obj_field(field_offset);
1267 
1268   log_debug(cds, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
1269 
1270   if (!CompressedOops::is_null(f)) {
1271     if (log_is_enabled(Trace, cds, heap)) {
1272       LogTarget(Trace, cds, heap) log;
1273       LogStream out(log);
1274       f->print_on(&out);
1275     }
1276 
1277     oop af = archive_reachable_objects_from(1, subgraph_info, f, is_closed_archive);
1278 
1279     if (af == NULL) {
1280       log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
1281                            klass_name, field_name);
1282     } else {
1283       // Note: the field value is not preserved in the archived mirror.
1284       // Record the field as a new subGraph entry point. The recorded
1285       // information is restored from the archive at runtime.
1286       subgraph_info->add_subgraph_entry_field(field_offset, af, is_closed_archive);
1287       log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(af));
1288     }
1289   } else {
1290     // The field contains null, we still need to record the entry point,
1291     // so it can be restored at runtime.
1292     subgraph_info->add_subgraph_entry_field(field_offset, NULL, false);
1293   }
1294 }
1295 
1296 #ifndef PRODUCT
1297 class VerifySharedOopClosure: public BasicOopIterateClosure {
1298  private:
1299   bool _is_archived;
1300 
1301  public:
1302   VerifySharedOopClosure(bool is_archived) : _is_archived(is_archived) {}
1303 
1304   void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
1305   void do_oop(      oop *p) { VerifySharedOopClosure::do_oop_work(p); }
1306 
1307  protected:
1308   template <class T> void do_oop_work(T *p) {
1309     oop obj = RawAccess<>::oop_load(p);
1310     if (!CompressedOops::is_null(obj)) {
1311       HeapShared::verify_reachable_objects_from(obj, _is_archived);
1312     }
1313   }
1314 };
1315 
1316 void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
1317   assert(DumpSharedSpaces, "dump time only");
1318   assert(k->is_shared_boot_class(), "must be boot class");
1319 
1320   oop m = k->java_mirror();
1321   oop f = m->obj_field(field_offset);
1322   if (!CompressedOops::is_null(f)) {
1323     verify_subgraph_from(f);
1324   }
1325 }
1326 
1327 void HeapShared::verify_subgraph_from(oop orig_obj) {
1328   oop archived_obj = find_archived_heap_object(orig_obj);
1329   if (archived_obj == NULL) {
1330     // It's OK for the root of a subgraph to be not archived. See comments in
1331     // archive_reachable_objects_from().
1332     return;
1333   }
1334 
1335   // Verify that all objects reachable from orig_obj are archived.
1336   init_seen_objects_table();
1337   verify_reachable_objects_from(orig_obj, false);
1338   delete_seen_objects_table();
1339 
1340   // Note: we could also verify that all objects reachable from the archived
1341   // copy of orig_obj can only point to archived objects, with:
1342   //      init_seen_objects_table();
1343   //      verify_reachable_objects_from(archived_obj, true);
1344   //      init_seen_objects_table();
1345   // but that's already done in G1HeapVerifier::verify_archive_regions so we
1346   // won't do it here.
1347 }
1348 
1349 void HeapShared::verify_reachable_objects_from(oop obj, bool is_archived) {
1350   _num_total_verifications ++;
1351   if (!has_been_seen_during_subgraph_recording(obj)) {
1352     set_has_been_seen_during_subgraph_recording(obj);
1353 
1354     if (is_archived) {
1355       assert(is_archived_object_during_dumptime(obj), "must be");
1356       assert(find_archived_heap_object(obj) == NULL, "must be");
1357     } else {
1358       assert(!is_archived_object_during_dumptime(obj), "must be");
1359       assert(find_archived_heap_object(obj) != NULL, "must be");
1360     }
1361 
1362     VerifySharedOopClosure walker(is_archived);
1363     obj->oop_iterate(&walker);
1364   }
1365 }
1366 #endif
1367 
1368 HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = NULL;
1369 int HeapShared::_num_new_walked_objs;
1370 int HeapShared::_num_new_archived_objs;
1371 int HeapShared::_num_old_recorded_klasses;
1372 
1373 int HeapShared::_num_total_subgraph_recordings = 0;
1374 int HeapShared::_num_total_walked_objs = 0;
1375 int HeapShared::_num_total_archived_objs = 0;
1376 int HeapShared::_num_total_recorded_klasses = 0;
1377 int HeapShared::_num_total_verifications = 0;
1378 
1379 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
1380   return _seen_objects_table->get(obj) != NULL;
1381 }
1382 
1383 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
1384   assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
1385   _seen_objects_table->put(obj, true);
1386   ++ _num_new_walked_objs;
1387 }
1388 
1389 void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
1390   log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
1391   init_subgraph_info(k, is_full_module_graph);
1392   init_seen_objects_table();
1393   _num_new_walked_objs = 0;
1394   _num_new_archived_objs = 0;
1395   _num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
1396 }
1397 
1398 void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
1399   int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
1400     _num_old_recorded_klasses;
1401   log_info(cds, heap)("Done recording subgraph(s) for archived fields in %s: "
1402                       "walked %d objs, archived %d new objs, recorded %d classes",
1403                       class_name, _num_new_walked_objs, _num_new_archived_objs,
1404                       num_new_recorded_klasses);
1405 
1406   delete_seen_objects_table();
1407 
1408   _num_total_subgraph_recordings ++;
1409   _num_total_walked_objs      += _num_new_walked_objs;
1410   _num_total_archived_objs    += _num_new_archived_objs;
1411   _num_total_recorded_klasses +=  num_new_recorded_klasses;
1412 }
1413 
1414 class ArchivableStaticFieldFinder: public FieldClosure {
1415   InstanceKlass* _ik;
1416   Symbol* _field_name;
1417   bool _found;
1418   int _offset;
1419 public:
1420   ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
1421     _ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
1422 
1423   virtual void do_field(fieldDescriptor* fd) {
1424     if (fd->name() == _field_name) {
1425       assert(!_found, "fields cannot be overloaded");
1426       assert(is_reference_type(fd->field_type()), "can archive only fields that are references");
1427       _found = true;
1428       _offset = fd->offset();
1429     }
1430   }
1431   bool found()     { return _found;  }
1432   int offset()     { return _offset; }
1433 };
1434 
1435 void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
1436                                             int num, TRAPS) {
1437   for (int i = 0; i < num; i++) {
1438     ArchivableStaticFieldInfo* info = &fields[i];
1439     TempNewSymbol klass_name =  SymbolTable::new_symbol(info->klass_name);
1440     TempNewSymbol field_name =  SymbolTable::new_symbol(info->field_name);
1441 
1442     Klass* k = SystemDictionary::resolve_or_fail(klass_name, true, CHECK);
1443     InstanceKlass* ik = InstanceKlass::cast(k);
1444     assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
1445            "Only support boot classes");
1446     ik->initialize(CHECK);
1447 
1448     ArchivableStaticFieldFinder finder(ik, field_name);
1449     ik->do_local_static_fields(&finder);
1450     assert(finder.found(), "field must exist");
1451 
1452     info->klass = ik;
1453     info->offset = finder.offset();
1454   }
1455 }
1456 
1457 void HeapShared::init_subgraph_entry_fields(TRAPS) {
1458   assert(HeapShared::can_write(), "must be");
1459   _dump_time_subgraph_info_table = new (ResourceObj::C_HEAP, mtClass)DumpTimeKlassSubGraphInfoTable();
1460   init_subgraph_entry_fields(closed_archive_subgraph_entry_fields,
1461                              num_closed_archive_subgraph_entry_fields,
1462                              CHECK);
1463   init_subgraph_entry_fields(open_archive_subgraph_entry_fields,
1464                              num_open_archive_subgraph_entry_fields,
1465                              CHECK);
1466   if (MetaspaceShared::use_full_module_graph()) {
1467     init_subgraph_entry_fields(fmg_open_archive_subgraph_entry_fields,
1468                                num_fmg_open_archive_subgraph_entry_fields,
1469                                CHECK);
1470   }
1471 }
1472 
1473 void HeapShared::init_for_dumping(TRAPS) {
1474   if (HeapShared::can_write()) {
1475     _dumped_interned_strings = new (ResourceObj::C_HEAP, mtClass)DumpedInternedStrings();
1476     init_subgraph_entry_fields(CHECK);
1477   }
1478 }
1479 
1480 void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
1481                                           int num, bool is_closed_archive,
1482                                           bool is_full_module_graph) {
1483   _num_total_subgraph_recordings = 0;
1484   _num_total_walked_objs = 0;
1485   _num_total_archived_objs = 0;
1486   _num_total_recorded_klasses = 0;
1487   _num_total_verifications = 0;
1488 
1489   // For each class X that has one or more archived fields:
1490   // [1] Dump the subgraph of each archived field
1491   // [2] Create a list of all the class of the objects that can be reached
1492   //     by any of these static fields.
1493   //     At runtime, these classes are initialized before X's archived fields
1494   //     are restored by HeapShared::initialize_from_archived_subgraph().
1495   int i;
1496   for (i = 0; i < num; ) {
1497     ArchivableStaticFieldInfo* info = &fields[i];
1498     const char* klass_name = info->klass_name;
1499     start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
1500 
1501     // If you have specified consecutive fields of the same klass in
1502     // fields[], these will be archived in the same
1503     // {start_recording_subgraph ... done_recording_subgraph} pass to
1504     // save time.
1505     for (; i < num; i++) {
1506       ArchivableStaticFieldInfo* f = &fields[i];
1507       if (f->klass_name != klass_name) {
1508         break;
1509       }
1510 
1511       archive_reachable_objects_from_static_field(f->klass, f->klass_name,
1512                                                   f->offset, f->field_name,
1513                                                   is_closed_archive);
1514     }
1515     done_recording_subgraph(info->klass, klass_name);
1516   }
1517 
1518   log_info(cds, heap)("Archived subgraph records in %s archive heap region = %d",
1519                       is_closed_archive ? "closed" : "open",
1520                       _num_total_subgraph_recordings);
1521   log_info(cds, heap)("  Walked %d objects", _num_total_walked_objs);
1522   log_info(cds, heap)("  Archived %d objects", _num_total_archived_objs);
1523   log_info(cds, heap)("  Recorded %d klasses", _num_total_recorded_klasses);
1524 
1525 #ifndef PRODUCT
1526   for (int i = 0; i < num; i++) {
1527     ArchivableStaticFieldInfo* f = &fields[i];
1528     verify_subgraph_from_static_field(f->klass, f->offset);
1529   }
1530   log_info(cds, heap)("  Verified %d references", _num_total_verifications);
1531 #endif
1532 }
1533 
1534 // Not all the strings in the global StringTable are dumped into the archive, because
1535 // some of those strings may be only referenced by classes that are excluded from
1536 // the archive. We need to explicitly mark the strings that are:
1537 //   [1] used by classes that WILL be archived;
1538 //   [2] included in the SharedArchiveConfigFile.
1539 void HeapShared::add_to_dumped_interned_strings(oop string) {
1540   assert_at_safepoint(); // DumpedInternedStrings uses raw oops
1541   bool created;
1542   _dumped_interned_strings->put_if_absent(string, true, &created);
1543 }
1544 
1545 // At dump-time, find the location of all the non-null oop pointers in an archived heap
1546 // region. This way we can quickly relocate all the pointers without using
1547 // BasicOopIterateClosure at runtime.
1548 class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
1549   void* _start;
1550   BitMap *_oopmap;
1551   int _num_total_oops;
1552   int _num_null_oops;
1553  public:
1554   FindEmbeddedNonNullPointers(void* start, BitMap* oopmap)
1555     : _start(start), _oopmap(oopmap), _num_total_oops(0),  _num_null_oops(0) {}
1556 
1557   virtual void do_oop(narrowOop* p) {
1558     _num_total_oops ++;
1559     narrowOop v = *p;
1560     if (!CompressedOops::is_null(v)) {
1561       size_t idx = p - (narrowOop*)_start;
1562       _oopmap->set_bit(idx);
1563     } else {
1564       _num_null_oops ++;
1565     }
1566   }
1567   virtual void do_oop(oop* p) {
1568     _num_total_oops ++;
1569     if ((*p) != NULL) {
1570       size_t idx = p - (oop*)_start;
1571       _oopmap->set_bit(idx);
1572     } else {
1573       _num_null_oops ++;
1574     }
1575   }
1576   int num_total_oops() const { return _num_total_oops; }
1577   int num_null_oops()  const { return _num_null_oops; }
1578 };
1579 
1580 ResourceBitMap HeapShared::calculate_oopmap(MemRegion region) {
1581   size_t num_bits = region.byte_size() / (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
1582   ResourceBitMap oopmap(num_bits);
1583 
1584   HeapWord* p   = region.start();
1585   HeapWord* end = region.end();
1586   FindEmbeddedNonNullPointers finder((void*)p, &oopmap);
1587   ArchiveBuilder* builder = DumpSharedSpaces ? ArchiveBuilder::current() : NULL;
1588 
1589   int num_objs = 0;
1590   while (p < end) {
1591     oop o = cast_to_oop(p);
1592     o->oop_iterate(&finder);
1593     p += o->size();
1594     if (DumpSharedSpaces) {
1595       builder->relocate_klass_ptr(o);
1596     }
1597     ++ num_objs;
1598   }
1599 
1600   log_info(cds, heap)("calculate_oopmap: objects = %6d, embedded oops = %7d, nulls = %7d",
1601                       num_objs, finder.num_total_oops(), finder.num_null_oops());
1602   return oopmap;
1603 }
1604 
1605 // Patch all the embedded oop pointers inside an archived heap region,
1606 // to be consistent with the runtime oop encoding.
1607 class PatchCompressedEmbeddedPointers: public BitMapClosure {
1608   narrowOop* _start;
1609 
1610  public:
1611   PatchCompressedEmbeddedPointers(narrowOop* start) : _start(start) {}
1612 
1613   bool do_bit(size_t offset) {
1614     narrowOop* p = _start + offset;
1615     narrowOop v = *p;
1616     assert(!CompressedOops::is_null(v), "null oops should have been filtered out at dump time");
1617     oop o = HeapShared::decode_from_archive(v);
1618     RawAccess<IS_NOT_NULL>::oop_store(p, o);
1619     return true;
1620   }
1621 };
1622 
1623 class PatchUncompressedEmbeddedPointers: public BitMapClosure {
1624   oop* _start;
1625 
1626  public:
1627   PatchUncompressedEmbeddedPointers(oop* start) : _start(start) {}
1628 
1629   bool do_bit(size_t offset) {
1630     oop* p = _start + offset;
1631     intptr_t dumptime_oop = (intptr_t)((void*)*p);
1632     assert(dumptime_oop != 0, "null oops should have been filtered out at dump time");
1633     intptr_t runtime_oop = dumptime_oop + HeapShared::runtime_delta();
1634     RawAccess<IS_NOT_NULL>::oop_store(p, cast_to_oop(runtime_oop));
1635     return true;
1636   }
1637 };
1638 
1639 // Patch all the non-null pointers that are embedded in the archived heap objects
1640 // in this region
1641 void HeapShared::patch_embedded_pointers(MemRegion region, address oopmap,
1642                                          size_t oopmap_size_in_bits) {
1643   BitMapView bm((BitMap::bm_word_t*)oopmap, oopmap_size_in_bits);
1644 
1645 #ifndef PRODUCT
1646   ResourceMark rm;
1647   ResourceBitMap checkBm = calculate_oopmap(region);
1648   assert(bm.is_same(checkBm), "sanity");
1649 #endif
1650 
1651   if (UseCompressedOops) {
1652     PatchCompressedEmbeddedPointers patcher((narrowOop*)region.start());
1653     bm.iterate(&patcher);
1654   } else {
1655     PatchUncompressedEmbeddedPointers patcher((oop*)region.start());
1656     bm.iterate(&patcher);
1657   }
1658 }
1659 
1660 // The CDS archive remembers each heap object by its address at dump time, but
1661 // the heap object may be loaded at a different address at run time. This structure is used
1662 // to translate the dump time addresses for all objects in FileMapInfo::space_at(region_index)
1663 // to their runtime addresses.
1664 struct LoadedArchiveHeapRegion {
1665   int       _region_index;   // index for FileMapInfo::space_at(index)
1666   size_t    _region_size;    // number of bytes in this region
1667   uintptr_t _dumptime_base;  // The dump-time (decoded) address of the first object in this region
1668   intx      _runtime_offset; // If an object's dump time address P is within in this region, its
1669                              // runtime address is P + _runtime_offset
1670 
1671   static int comparator(const void* a, const void* b) {
1672     LoadedArchiveHeapRegion* reg_a = (LoadedArchiveHeapRegion*)a;
1673     LoadedArchiveHeapRegion* reg_b = (LoadedArchiveHeapRegion*)b;
1674     if (reg_a->_dumptime_base < reg_b->_dumptime_base) {
1675       return -1;
1676     } else if (reg_a->_dumptime_base == reg_b->_dumptime_base) {
1677       return 0;
1678     } else {
1679       return 1;
1680     }
1681   }
1682 
1683   uintptr_t top() {
1684     return _dumptime_base + _region_size;
1685   }
1686 };
1687 
1688 void HeapShared::init_loaded_heap_relocation(LoadedArchiveHeapRegion* loaded_regions,
1689                                              int num_loaded_regions) {
1690   _dumptime_base_0 = loaded_regions[0]._dumptime_base;
1691   _dumptime_base_1 = loaded_regions[1]._dumptime_base;
1692   _dumptime_base_2 = loaded_regions[2]._dumptime_base;
1693   _dumptime_base_3 = loaded_regions[3]._dumptime_base;
1694   _dumptime_top = loaded_regions[num_loaded_regions-1].top();
1695 
1696   _runtime_offset_0 = loaded_regions[0]._runtime_offset;
1697   _runtime_offset_1 = loaded_regions[1]._runtime_offset;
1698   _runtime_offset_2 = loaded_regions[2]._runtime_offset;
1699   _runtime_offset_3 = loaded_regions[3]._runtime_offset;
1700 
1701   assert(2 <= num_loaded_regions && num_loaded_regions <= 4, "must be");
1702   if (num_loaded_regions < 4) {
1703     _dumptime_base_3 = UINTPTR_MAX;
1704   }
1705   if (num_loaded_regions < 3) {
1706     _dumptime_base_2 = UINTPTR_MAX;
1707   }
1708 }
1709 
1710 bool HeapShared::can_load() {
1711   return Universe::heap()->can_load_archived_objects();
1712 }
1713 
1714 template <int NUM_LOADED_REGIONS>
1715 class PatchLoadedRegionPointers: public BitMapClosure {
1716   narrowOop* _start;
1717   intx _offset_0;
1718   intx _offset_1;
1719   intx _offset_2;
1720   intx _offset_3;
1721   uintptr_t _base_0;
1722   uintptr_t _base_1;
1723   uintptr_t _base_2;
1724   uintptr_t _base_3;
1725   uintptr_t _top;
1726 
1727   static_assert(MetaspaceShared::max_num_heap_regions == 4, "can't handle more than 4 regions");
1728   static_assert(NUM_LOADED_REGIONS >= 2, "we have at least 2 loaded regions");
1729   static_assert(NUM_LOADED_REGIONS <= 4, "we have at most 4 loaded regions");
1730 
1731  public:
1732   PatchLoadedRegionPointers(narrowOop* start, LoadedArchiveHeapRegion* loaded_regions)
1733     : _start(start),
1734       _offset_0(loaded_regions[0]._runtime_offset),
1735       _offset_1(loaded_regions[1]._runtime_offset),
1736       _offset_2(loaded_regions[2]._runtime_offset),
1737       _offset_3(loaded_regions[3]._runtime_offset),
1738       _base_0(loaded_regions[0]._dumptime_base),
1739       _base_1(loaded_regions[1]._dumptime_base),
1740       _base_2(loaded_regions[2]._dumptime_base),
1741       _base_3(loaded_regions[3]._dumptime_base) {
1742     _top = loaded_regions[NUM_LOADED_REGIONS-1].top();
1743   }
1744 
1745   bool do_bit(size_t offset) {
1746     narrowOop* p = _start + offset;
1747     narrowOop v = *p;
1748     assert(!CompressedOops::is_null(v), "null oops should have been filtered out at dump time");
1749     uintptr_t o = cast_from_oop<uintptr_t>(HeapShared::decode_from_archive(v));
1750     assert(_base_0 <= o && o < _top, "must be");
1751 
1752 
1753     // We usually have only 2 regions for the default archive. Use template to avoid unnecessary comparisons.
1754     if (NUM_LOADED_REGIONS > 3 && o >= _base_3) {
1755       o += _offset_3;
1756     } else if (NUM_LOADED_REGIONS > 2 && o >= _base_2) {
1757       o += _offset_2;
1758     } else if (o >= _base_1) {
1759       o += _offset_1;
1760     } else {
1761       o += _offset_0;
1762     }
1763     HeapShared::assert_in_loaded_heap(o);
1764     RawAccess<IS_NOT_NULL>::oop_store(p, cast_to_oop(o));
1765     return true;
1766   }
1767 };
1768 
1769 int HeapShared::init_loaded_regions(FileMapInfo* mapinfo, LoadedArchiveHeapRegion* loaded_regions,
1770                                     MemRegion& archive_space) {
1771   size_t total_bytes = 0;
1772   int num_loaded_regions = 0;
1773   for (int i = MetaspaceShared::first_archive_heap_region;
1774        i <= MetaspaceShared::last_archive_heap_region; i++) {
1775     FileMapRegion* r = mapinfo->space_at(i);
1776     r->assert_is_heap_region();
1777     if (r->used() > 0) {
1778       assert(is_aligned(r->used(), HeapWordSize), "must be");
1779       total_bytes += r->used();
1780       LoadedArchiveHeapRegion* ri = &loaded_regions[num_loaded_regions++];
1781       ri->_region_index = i;
1782       ri->_region_size = r->used();
1783       ri->_dumptime_base = (uintptr_t)mapinfo->start_address_as_decoded_from_archive(r);
1784     }
1785   }
1786 
1787   assert(is_aligned(total_bytes, HeapWordSize), "must be");
1788   size_t word_size = total_bytes / HeapWordSize;
1789   HeapWord* buffer = Universe::heap()->allocate_loaded_archive_space(word_size);
1790   if (buffer == nullptr) {
1791     return 0;
1792   }
1793 
1794   archive_space = MemRegion(buffer, word_size);
1795   _loaded_heap_bottom = (uintptr_t)archive_space.start();
1796   _loaded_heap_top    = _loaded_heap_bottom + total_bytes;
1797 
1798   return num_loaded_regions;
1799 }
1800 
1801 void HeapShared::sort_loaded_regions(LoadedArchiveHeapRegion* loaded_regions, int num_loaded_regions,
1802                                      uintptr_t buffer) {
1803   // Find the relocation offset of the pointers in each region
1804   qsort(loaded_regions, num_loaded_regions, sizeof(LoadedArchiveHeapRegion),
1805         LoadedArchiveHeapRegion::comparator);
1806 
1807   uintptr_t p = buffer;
1808   for (int i = 0; i < num_loaded_regions; i++) {
1809     // This region will be loaded at p, so all objects inside this
1810     // region will be shifted by ri->offset
1811     LoadedArchiveHeapRegion* ri = &loaded_regions[i];
1812     ri->_runtime_offset = p - ri->_dumptime_base;
1813     p += ri->_region_size;
1814   }
1815   assert(p == _loaded_heap_top, "must be");
1816 }
1817 
1818 bool HeapShared::load_regions(FileMapInfo* mapinfo, LoadedArchiveHeapRegion* loaded_regions,
1819                               int num_loaded_regions, uintptr_t buffer) {
1820   uintptr_t bitmap_base = (uintptr_t)mapinfo->map_bitmap_region();
1821   if (bitmap_base == 0) {
1822     _loading_failed = true;
1823     return false; // OOM or CRC error
1824   }
1825   uintptr_t load_address = buffer;
1826   for (int i = 0; i < num_loaded_regions; i++) {
1827     LoadedArchiveHeapRegion* ri = &loaded_regions[i];
1828     FileMapRegion* r = mapinfo->space_at(ri->_region_index);
1829 
1830     if (!mapinfo->read_region(ri->_region_index, (char*)load_address, r->used(), /* do_commit = */ false)) {
1831       // There's no easy way to free the buffer, so we will fill it with zero later
1832       // in fill_failed_loaded_region(), and it will eventually be GC'ed.
1833       log_warning(cds)("Loading of heap region %d has failed. Archived objects are disabled", i);
1834       _loading_failed = true;
1835       return false;
1836     }
1837     log_info(cds)("Loaded heap    region #%d at base " INTPTR_FORMAT " top " INTPTR_FORMAT
1838                   " size " SIZE_FORMAT_W(6) " delta " INTX_FORMAT,
1839                   ri->_region_index, load_address, load_address + ri->_region_size,
1840                   ri->_region_size, ri->_runtime_offset);
1841 
1842     uintptr_t oopmap = bitmap_base + r->oopmap_offset();
1843     BitMapView bm((BitMap::bm_word_t*)oopmap, r->oopmap_size_in_bits());
1844 
1845     if (num_loaded_regions == 4) {
1846       PatchLoadedRegionPointers<4> patcher((narrowOop*)load_address, loaded_regions);
1847       bm.iterate(&patcher);
1848     } else if (num_loaded_regions == 3) {
1849       PatchLoadedRegionPointers<3> patcher((narrowOop*)load_address, loaded_regions);
1850       bm.iterate(&patcher);
1851     } else {
1852       assert(num_loaded_regions == 2, "must be");
1853       PatchLoadedRegionPointers<2> patcher((narrowOop*)load_address, loaded_regions);
1854       bm.iterate(&patcher);
1855     }
1856 
1857     load_address += r->used();
1858   }
1859 
1860   return true;
1861 }
1862 
1863 bool HeapShared::load_heap_regions(FileMapInfo* mapinfo) {
1864   init_narrow_oop_decoding(mapinfo->narrow_oop_base(), mapinfo->narrow_oop_shift());
1865 
1866   LoadedArchiveHeapRegion loaded_regions[MetaspaceShared::max_num_heap_regions];
1867   memset(loaded_regions, 0, sizeof(loaded_regions));
1868 
1869   MemRegion archive_space;
1870   int num_loaded_regions = init_loaded_regions(mapinfo, loaded_regions, archive_space);
1871   if (num_loaded_regions <= 0) {
1872     return false;
1873   }
1874   sort_loaded_regions(loaded_regions, num_loaded_regions, (uintptr_t)archive_space.start());
1875   if (!load_regions(mapinfo, loaded_regions, num_loaded_regions, (uintptr_t)archive_space.start())) {
1876     assert(_loading_failed, "must be");
1877     return false;
1878   }
1879 
1880   init_loaded_heap_relocation(loaded_regions, num_loaded_regions);
1881   _is_loaded = true;
1882 
1883   return true;
1884 }
1885 
1886 class VerifyLoadedHeapEmbeddedPointers: public BasicOopIterateClosure {
1887   ResourceHashtable<uintptr_t, bool>* _table;
1888 
1889  public:
1890   VerifyLoadedHeapEmbeddedPointers(ResourceHashtable<uintptr_t, bool>* table) : _table(table) {}
1891 
1892   virtual void do_oop(narrowOop* p) {
1893     // This should be called before the loaded regions are modified, so all the embedded pointers
1894     // must be NULL, or must point to a valid object in the loaded regions.
1895     narrowOop v = *p;
1896     if (!CompressedOops::is_null(v)) {
1897       oop o = CompressedOops::decode_not_null(v);
1898       uintptr_t u = cast_from_oop<uintptr_t>(o);
1899       HeapShared::assert_in_loaded_heap(u);
1900       guarantee(_table->contains(u), "must point to beginning of object in loaded archived regions");
1901     }
1902   }
1903   virtual void do_oop(oop* p) {
1904     ShouldNotReachHere();
1905   }
1906 };
1907 
1908 void HeapShared::finish_initialization() {
1909   if (is_loaded()) {
1910     HeapWord* bottom = (HeapWord*)_loaded_heap_bottom;
1911     HeapWord* top    = (HeapWord*)_loaded_heap_top;
1912 
1913     MemRegion archive_space = MemRegion(bottom, top);
1914     Universe::heap()->complete_loaded_archive_space(archive_space);
1915   }
1916 
1917   if (VerifyArchivedFields <= 0 || !is_loaded()) {
1918     return;
1919   }
1920 
1921   log_info(cds, heap)("Verify all oops and pointers in loaded heap");
1922 
1923   ResourceMark rm;
1924   ResourceHashtable<uintptr_t, bool> table;
1925   VerifyLoadedHeapEmbeddedPointers verifier(&table);
1926   HeapWord* bottom = (HeapWord*)_loaded_heap_bottom;
1927   HeapWord* top    = (HeapWord*)_loaded_heap_top;
1928 
1929   for (HeapWord* p = bottom; p < top; ) {
1930     oop o = cast_to_oop(p);
1931     table.put(cast_from_oop<uintptr_t>(o), true);
1932     p += o->size();
1933   }
1934 
1935   for (HeapWord* p = bottom; p < top; ) {
1936     oop o = cast_to_oop(p);
1937     o->oop_iterate(&verifier);
1938     p += o->size();
1939   }
1940 }
1941 
1942 void HeapShared::fill_failed_loaded_region() {
1943   assert(_loading_failed, "must be");
1944   if (_loaded_heap_bottom != 0) {
1945     assert(_loaded_heap_top != 0, "must be");
1946     HeapWord* bottom = (HeapWord*)_loaded_heap_bottom;
1947     HeapWord* top = (HeapWord*)_loaded_heap_top;
1948     Universe::heap()->fill_with_objects(bottom, top - bottom);
1949   }
1950 }
1951 
1952 #endif // INCLUDE_CDS_JAVA_HEAP