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/archiveHeapLoader.hpp"
  28 #include "cds/archiveUtils.hpp"
  29 #include "cds/cdsHeapVerifier.hpp"
  30 #include "cds/heapShared.hpp"
  31 #include "cds/metaspaceShared.hpp"
  32 #include "classfile/classLoaderData.hpp"
  33 #include "classfile/javaClasses.inline.hpp"
  34 #include "classfile/modules.hpp"
  35 #include "classfile/stringTable.hpp"
  36 #include "classfile/symbolTable.hpp"
  37 #include "classfile/systemDictionary.hpp"
  38 #include "classfile/systemDictionaryShared.hpp"
  39 #include "classfile/vmClasses.hpp"
  40 #include "classfile/vmSymbols.hpp"
  41 #include "gc/shared/collectedHeap.hpp"
  42 #include "gc/shared/gcLocker.hpp"
  43 #include "gc/shared/gcVMOperations.hpp"
  44 #include "logging/log.hpp"
  45 #include "logging/logStream.hpp"
  46 #include "memory/iterator.inline.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.inline.hpp"
  52 #include "oops/oop.inline.hpp"
  53 #include "oops/typeArrayOop.inline.hpp"
  54 #include "prims/jvmtiExport.hpp"
  55 #include "runtime/fieldDescriptor.inline.hpp"
  56 #include "runtime/init.hpp"
  57 #include "runtime/javaCalls.hpp"
  58 #include "runtime/safepoint.hpp"
  59 #include "runtime/safepointVerifiers.hpp"
  60 #include "utilities/bitMap.inline.hpp"
  61 #include "utilities/copy.hpp"
  62 #if INCLUDE_G1GC
  63 #include "gc/g1/g1CollectedHeap.hpp"
  64 #endif
  65 
  66 #if INCLUDE_CDS_JAVA_HEAP
  67 
  68 struct ArchivableStaticFieldInfo {
  69   const char* klass_name;
  70   const char* field_name;
  71   InstanceKlass* klass;
  72   int offset;
  73   BasicType type;
  74 
  75   ArchivableStaticFieldInfo(const char* k, const char* f)
  76   : klass_name(k), field_name(f), klass(NULL), offset(0), type(T_ILLEGAL) {}
  77 
  78   bool valid() {
  79     return klass_name != NULL;
  80   }
  81 };
  82 
  83 bool HeapShared::_disable_writing = false;
  84 DumpedInternedStrings *HeapShared::_dumped_interned_strings = NULL;
  85 GrowableArrayCHeap<Metadata**, mtClassShared>* HeapShared::_native_pointers = NULL;
  86 
  87 size_t HeapShared::_alloc_count[HeapShared::ALLOC_STAT_SLOTS];
  88 size_t HeapShared::_alloc_size[HeapShared::ALLOC_STAT_SLOTS];
  89 size_t HeapShared::_total_obj_count;
  90 size_t HeapShared::_total_obj_size;
  91 
  92 #ifndef PRODUCT
  93 #define ARCHIVE_TEST_FIELD_NAME "archivedObjects"
  94 static Array<char>* _archived_ArchiveHeapTestClass = NULL;
  95 static const char* _test_class_name = NULL;
  96 static const Klass* _test_class = NULL;
  97 static const ArchivedKlassSubGraphInfoRecord* _test_class_record = NULL;
  98 #endif
  99 
 100 
 101 //
 102 // If you add new entries to the following tables, you should know what you're doing!
 103 //
 104 
 105 // Entry fields for shareable subgraphs archived in the closed archive heap
 106 // region. Warning: Objects in the subgraphs should not have reference fields
 107 // assigned at runtime.
 108 static ArchivableStaticFieldInfo closed_archive_subgraph_entry_fields[] = {
 109   {"java/lang/Integer$IntegerCache",              "archivedCache"},
 110   {"java/lang/Long$LongCache",                    "archivedCache"},
 111   {"java/lang/Byte$ByteCache",                    "archivedCache"},
 112   {"java/lang/Short$ShortCache",                  "archivedCache"},
 113   {"java/lang/Character$CharacterCache",          "archivedCache"},
 114   {"java/util/jar/Attributes$Name",               "KNOWN_NAMES"},
 115   {"sun/util/locale/BaseLocale",                  "constantBaseLocales"},
 116   {NULL, NULL},
 117 };
 118 // Entry fields for subgraphs archived in the open archive heap region.
 119 static ArchivableStaticFieldInfo open_archive_subgraph_entry_fields[] = {
 120   {"jdk/internal/module/ArchivedModuleGraph",     "archivedModuleGraph"},
 121   {"java/util/ImmutableCollections",              "archivedObjects"},
 122   {"java/lang/ModuleLayer",                       "EMPTY_LAYER"},
 123   {"java/lang/module/Configuration",              "EMPTY_CONFIGURATION"},
 124   {"jdk/internal/math/FDBigInteger",              "archivedCaches"},
 125 #ifndef PRODUCT
 126   {NULL, NULL}, // Extra slot for -XX:ArchiveHeapTestClass
 127 #endif
 128   {NULL, NULL},
 129 };
 130 
 131 // Entry fields for subgraphs archived in the open archive heap region (full module graph).
 132 static ArchivableStaticFieldInfo fmg_open_archive_subgraph_entry_fields[] = {
 133   {"jdk/internal/loader/ArchivedClassLoaders",    "archivedClassLoaders"},
 134   {"jdk/internal/module/ArchivedBootLayer",       "archivedBootLayer"},
 135   {"java/lang/Module$ArchivedData",               "archivedData"},
 136   {NULL, NULL},
 137 };
 138 
 139 GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = NULL;
 140 OopHandle HeapShared::_roots;
 141 
 142 #ifdef ASSERT
 143 bool HeapShared::is_archived_object_during_dumptime(oop p) {
 144   assert(HeapShared::can_write(), "must be");
 145   assert(DumpSharedSpaces, "this function is only used with -Xshare:dump");
 146   return Universe::heap()->is_archived_object(p);
 147 }
 148 #endif
 149 
 150 static bool is_subgraph_root_class_of(ArchivableStaticFieldInfo fields[], InstanceKlass* ik) {
 151   for (int i = 0; fields[i].valid(); i++) {
 152     if (fields[i].klass == ik) {
 153       return true;
 154     }
 155   }
 156   return false;
 157 }
 158 
 159 bool HeapShared::is_subgraph_root_class(InstanceKlass* ik) {
 160   return is_subgraph_root_class_of(closed_archive_subgraph_entry_fields, ik) ||
 161          is_subgraph_root_class_of(open_archive_subgraph_entry_fields, ik) ||
 162          is_subgraph_root_class_of(fmg_open_archive_subgraph_entry_fields, ik);
 163 }
 164 
 165 unsigned HeapShared::oop_hash(oop const& p) {
 166   // Do not call p->identity_hash() as that will update the
 167   // object header.
 168   return primitive_hash(cast_from_oop<intptr_t>(p));
 169 }
 170 
 171 static void reset_states(oop obj, TRAPS) {
 172   Handle h_obj(THREAD, obj);
 173   InstanceKlass* klass = InstanceKlass::cast(obj->klass());
 174   TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
 175   Symbol* method_sig = vmSymbols::void_method_signature();
 176 
 177   while (klass != NULL) {
 178     Method* method = klass->find_method(method_name, method_sig);
 179     if (method != NULL) {
 180       assert(method->is_private(), "must be");
 181       if (log_is_enabled(Debug, cds)) {
 182         ResourceMark rm(THREAD);
 183         log_debug(cds)("  calling %s", method->name_and_sig_as_C_string());
 184       }
 185       JavaValue result(T_VOID);
 186       JavaCalls::call_special(&result, h_obj, klass,
 187                               method_name, method_sig, CHECK);
 188     }
 189     klass = klass->java_super();
 190   }
 191 }
 192 
 193 void HeapShared::reset_archived_object_states(TRAPS) {
 194   assert(DumpSharedSpaces, "dump-time only");
 195   log_debug(cds)("Resetting platform loader");
 196   reset_states(SystemDictionary::java_platform_loader(), CHECK);
 197   log_debug(cds)("Resetting system loader");
 198   reset_states(SystemDictionary::java_system_loader(), CHECK);
 199 
 200   // Clean up jdk.internal.loader.ClassLoaders::bootLoader(), which is not
 201   // directly used for class loading, but rather is used by the core library
 202   // to keep track of resources, etc, loaded by the null class loader.
 203   //
 204   // Note, this object is non-null, and is not the same as
 205   // ClassLoaderData::the_null_class_loader_data()->class_loader(),
 206   // which is null.
 207   log_debug(cds)("Resetting boot loader");
 208   JavaValue result(T_OBJECT);
 209   JavaCalls::call_static(&result,
 210                          vmClasses::jdk_internal_loader_ClassLoaders_klass(),
 211                          vmSymbols::bootLoader_name(),
 212                          vmSymbols::void_BuiltinClassLoader_signature(),
 213                          CHECK);
 214   Handle boot_loader(THREAD, result.get_oop());
 215   reset_states(boot_loader(), CHECK);
 216 }
 217 
 218 HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = NULL;
 219 HeapShared::OriginalObjectTable* HeapShared::_original_object_table = NULL;
 220 oop HeapShared::find_archived_heap_object(oop obj) {
 221   assert(DumpSharedSpaces, "dump-time only");
 222   ArchivedObjectCache* cache = archived_object_cache();
 223   CachedOopInfo* p = cache->get(obj);
 224   if (p != NULL) {
 225     return p->_obj;
 226   } else {
 227     return NULL;
 228   }
 229 }
 230 
 231 int HeapShared::append_root(oop obj) {
 232   assert(DumpSharedSpaces, "dump-time only");
 233 
 234   // No GC should happen since we aren't scanning _pending_roots.
 235   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 236 
 237   if (_pending_roots == NULL) {
 238     _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
 239   }
 240 
 241   return _pending_roots->append(obj);
 242 }
 243 
 244 objArrayOop HeapShared::roots() {
 245   if (DumpSharedSpaces) {
 246     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 247     if (!HeapShared::can_write()) {
 248       return NULL;
 249     }
 250   } else {
 251     assert(UseSharedSpaces, "must be");
 252   }
 253 
 254   objArrayOop roots = (objArrayOop)_roots.resolve();
 255   assert(roots != NULL, "should have been initialized");
 256   return roots;
 257 }
 258 
 259 // Returns an objArray that contains all the roots of the archived objects
 260 oop HeapShared::get_root(int index, bool clear) {
 261   assert(index >= 0, "sanity");
 262   if (DumpSharedSpaces) {
 263     assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 264     assert(_pending_roots != NULL, "sanity");
 265     return _pending_roots->at(index);
 266   } else {
 267     assert(UseSharedSpaces, "must be");
 268     assert(!_roots.is_empty(), "must have loaded shared heap");
 269     oop result = roots()->obj_at(index);
 270     if (clear) {
 271       clear_root(index);
 272     }
 273     return result;
 274   }
 275 }
 276 
 277 void HeapShared::clear_root(int index) {
 278   assert(index >= 0, "sanity");
 279   assert(UseSharedSpaces, "must be");
 280   if (ArchiveHeapLoader::is_fully_available()) {
 281     if (log_is_enabled(Debug, cds, heap)) {
 282       oop old = roots()->obj_at(index);
 283       log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
 284     }
 285     roots()->obj_at_put(index, NULL);
 286   }
 287 }
 288 
 289 oop HeapShared::archive_object(oop obj) {
 290   assert(DumpSharedSpaces, "dump-time only");
 291 
 292   assert(!obj->is_stackChunk(), "do not archive stack chunks");
 293 
 294   oop ao = find_archived_heap_object(obj);
 295   if (ao != NULL) {
 296     // already archived
 297     return ao;
 298   }
 299 
 300   int len = obj->size();
 301   if (G1CollectedHeap::heap()->is_archive_alloc_too_large(len)) {
 302     log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
 303                          p2i(obj), (size_t)obj->size());
 304     return NULL;
 305   }
 306 
 307   oop archived_oop = cast_to_oop(G1CollectedHeap::heap()->archive_mem_allocate(len));
 308   if (archived_oop != NULL) {
 309     count_allocation(len);
 310     Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), cast_from_oop<HeapWord*>(archived_oop), len);
 311     // Reinitialize markword to remove age/marking/locking/etc.
 312     //
 313     // We need to retain the identity_hash, because it may have been used by some hashtables
 314     // in the shared heap. This also has the side effect of pre-initializing the
 315     // identity_hash for all shared objects, so they are less likely to be written
 316     // into during run time, increasing the potential of memory sharing.
 317     int hash_original = obj->identity_hash();
 318 
 319     assert(SafepointSynchronize::is_at_safepoint(), "resolving displaced headers only at safepoint");
 320     markWord mark = obj->mark();
 321     if (mark.has_displaced_mark_helper()) {
 322       mark = mark.displaced_mark_helper();
 323     }
 324     narrowKlass nklass = mark.narrow_klass();
 325     archived_oop->set_mark(markWord::prototype().copy_set_hash(hash_original) LP64_ONLY(.set_narrow_klass(nklass)));
 326     assert(archived_oop->mark().is_unlocked(), "sanity");
 327 
 328     DEBUG_ONLY(int hash_archived = archived_oop->identity_hash());
 329     assert(hash_original == hash_archived, "Different hash codes: original %x, archived %x", hash_original, hash_archived);
 330 
 331     ArchivedObjectCache* cache = archived_object_cache();
 332     CachedOopInfo info = make_cached_oop_info(archived_oop);
 333     cache->put(obj, info);
 334     if (_original_object_table != NULL) {
 335       _original_object_table->put(archived_oop, obj);
 336     }
 337     mark_native_pointers(obj, archived_oop);
 338     if (log_is_enabled(Debug, cds, heap)) {
 339       ResourceMark rm;
 340       log_debug(cds, heap)("Archived heap object " PTR_FORMAT " ==> " PTR_FORMAT " : %s",
 341                            p2i(obj), p2i(archived_oop), obj->klass()->external_name());
 342     }
 343   } else {
 344     log_error(cds, heap)(
 345       "Cannot allocate space for object " PTR_FORMAT " in archived heap region",
 346       p2i(obj));
 347     log_error(cds)("Out of memory. Please run with a larger Java heap, current MaxHeapSize = "
 348         SIZE_FORMAT "M", MaxHeapSize/M);
 349     os::_exit(-1);
 350   }
 351   return archived_oop;
 352 }
 353 
 354 void HeapShared::archive_klass_objects() {
 355   GrowableArray<Klass*>* klasses = ArchiveBuilder::current()->klasses();
 356   assert(klasses != NULL, "sanity");
 357   for (int i = 0; i < klasses->length(); i++) {
 358     Klass* k = ArchiveBuilder::get_buffered_klass(klasses->at(i));
 359 
 360     // archive mirror object
 361     java_lang_Class::archive_mirror(k);
 362 
 363     // archive the resolved_referenes array
 364     if (k->is_instance_klass()) {
 365       InstanceKlass* ik = InstanceKlass::cast(k);
 366       ik->constants()->archive_resolved_references();
 367     }
 368   }
 369 }
 370 
 371 void HeapShared::mark_native_pointers(oop orig_obj, oop archived_obj) {
 372   if (java_lang_Class::is_instance(orig_obj)) {
 373     mark_one_native_pointer(archived_obj, java_lang_Class::klass_offset());
 374     mark_one_native_pointer(archived_obj, java_lang_Class::array_klass_offset());
 375   }
 376 }
 377 
 378 void HeapShared::mark_one_native_pointer(oop archived_obj, int offset) {
 379   Metadata* ptr = archived_obj->metadata_field_acquire(offset);
 380   if (ptr != NULL) {
 381     // Set the native pointer to the requested address (at runtime, if the metadata
 382     // is mapped at the default location, it will be at this address).
 383     address buffer_addr = ArchiveBuilder::current()->get_buffered_addr((address)ptr);
 384     address requested_addr = ArchiveBuilder::current()->to_requested(buffer_addr);
 385     archived_obj->metadata_field_put(offset, (Metadata*)requested_addr);
 386 
 387     // Remember this pointer. At runtime, if the metadata is mapped at a non-default
 388     // location, the pointer needs to be patched (see ArchiveHeapLoader::patch_native_pointers()).
 389     _native_pointers->append(archived_obj->field_addr<Metadata*>(offset));
 390 
 391     log_debug(cds, heap, mirror)(
 392         "Marked metadata field at %d: " PTR_FORMAT " ==> " PTR_FORMAT,
 393          offset, p2i(ptr), p2i(requested_addr));
 394   }
 395 }
 396 
 397 // -- Handling of Enum objects
 398 // Java Enum classes have synthetic <clinit> methods that look like this
 399 //     enum MyEnum {FOO, BAR}
 400 //     MyEnum::<clinint> {
 401 //        /*static final MyEnum*/ MyEnum::FOO = new MyEnum("FOO");
 402 //        /*static final MyEnum*/ MyEnum::BAR = new MyEnum("BAR");
 403 //     }
 404 //
 405 // If MyEnum::FOO object is referenced by any of the archived subgraphs, we must
 406 // ensure the archived value equals (in object address) to the runtime value of
 407 // MyEnum::FOO.
 408 //
 409 // However, since MyEnum::<clinint> is synthetically generated by javac, there's
 410 // no way of programmatically handling this inside the Java code (as you would handle
 411 // ModuleLayer::EMPTY_LAYER, for example).
 412 //
 413 // Instead, we archive all static field of such Enum classes. At runtime,
 414 // HeapShared::initialize_enum_klass() will skip the <clinit> method and pull
 415 // the static fields out of the archived heap.
 416 void HeapShared::check_enum_obj(int level,
 417                                 KlassSubGraphInfo* subgraph_info,
 418                                 oop orig_obj,
 419                                 bool is_closed_archive) {
 420   Klass* k = orig_obj->klass();
 421   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(k);
 422   if (!k->is_instance_klass()) {
 423     return;
 424   }
 425   InstanceKlass* ik = InstanceKlass::cast(k);
 426   if (ik->java_super() == vmClasses::Enum_klass() && !ik->has_archived_enum_objs()) {
 427     ResourceMark rm;
 428     ik->set_has_archived_enum_objs();
 429     buffered_k->set_has_archived_enum_objs();
 430     oop mirror = ik->java_mirror();
 431 
 432     for (JavaFieldStream fs(ik); !fs.done(); fs.next()) {
 433       if (fs.access_flags().is_static()) {
 434         fieldDescriptor& fd = fs.field_descriptor();
 435         if (fd.field_type() != T_OBJECT && fd.field_type() != T_ARRAY) {
 436           guarantee(false, "static field %s::%s must be T_OBJECT or T_ARRAY",
 437                     ik->external_name(), fd.name()->as_C_string());
 438         }
 439         oop oop_field = mirror->obj_field(fd.offset());
 440         if (oop_field == NULL) {
 441           guarantee(false, "static field %s::%s must not be null",
 442                     ik->external_name(), fd.name()->as_C_string());
 443         } else if (oop_field->klass() != ik && oop_field->klass() != ik->array_klass_or_null()) {
 444           guarantee(false, "static field %s::%s is of the wrong type",
 445                     ik->external_name(), fd.name()->as_C_string());
 446         }
 447         oop archived_oop_field = archive_reachable_objects_from(level, subgraph_info, oop_field, is_closed_archive);
 448         int root_index = append_root(archived_oop_field);
 449         log_info(cds, heap)("Archived enum obj @%d %s::%s (" INTPTR_FORMAT " -> " INTPTR_FORMAT ")",
 450                             root_index, ik->external_name(), fd.name()->as_C_string(),
 451                             p2i((oopDesc*)oop_field), p2i((oopDesc*)archived_oop_field));
 452         SystemDictionaryShared::add_enum_klass_static_field(ik, root_index);
 453       }
 454     }
 455   }
 456 }
 457 
 458 // See comments in HeapShared::check_enum_obj()
 459 bool HeapShared::initialize_enum_klass(InstanceKlass* k, TRAPS) {
 460   if (!ArchiveHeapLoader::is_fully_available()) {
 461     return false;
 462   }
 463 
 464   RunTimeClassInfo* info = RunTimeClassInfo::get_for(k);
 465   assert(info != NULL, "sanity");
 466 
 467   if (log_is_enabled(Info, cds, heap)) {
 468     ResourceMark rm;
 469     log_info(cds, heap)("Initializing Enum class: %s", k->external_name());
 470   }
 471 
 472   oop mirror = k->java_mirror();
 473   int i = 0;
 474   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
 475     if (fs.access_flags().is_static()) {
 476       int root_index = info->enum_klass_static_field_root_index_at(i++);
 477       fieldDescriptor& fd = fs.field_descriptor();
 478       assert(fd.field_type() == T_OBJECT || fd.field_type() == T_ARRAY, "must be");
 479       mirror->obj_field_put(fd.offset(), get_root(root_index, /*clear=*/true));
 480     }
 481   }
 482   return true;
 483 }
 484 
 485 void HeapShared::run_full_gc_in_vm_thread() {
 486   if (HeapShared::can_write()) {
 487     // Avoid fragmentation while archiving heap objects.
 488     // We do this inside a safepoint, so that no further allocation can happen after GC
 489     // has finished.
 490     if (GCLocker::is_active()) {
 491       // Just checking for safety ...
 492       // This should not happen during -Xshare:dump. If you see this, probably the Java core lib
 493       // has been modified such that JNI code is executed in some clean up threads after
 494       // we have finished class loading.
 495       log_warning(cds)("GC locker is held, unable to start extra compacting GC. This may produce suboptimal results.");
 496     } else {
 497       log_info(cds)("Run GC ...");
 498       Universe::heap()->collect_as_vm_thread(GCCause::_archive_time_gc);
 499       log_info(cds)("Run GC done");
 500     }
 501   }
 502 }
 503 
 504 void HeapShared::archive_objects(GrowableArray<MemRegion>* closed_regions,
 505                                  GrowableArray<MemRegion>* open_regions) {
 506 
 507   G1HeapVerifier::verify_ready_for_archiving();
 508 
 509   {
 510     NoSafepointVerifier nsv;
 511 
 512     // Cache for recording where the archived objects are copied to
 513     create_archived_object_cache(log_is_enabled(Info, cds, map));
 514 
 515     log_info(cds)("Heap range = [" PTR_FORMAT " - "  PTR_FORMAT "]",
 516                    UseCompressedOops ? p2i(CompressedOops::begin()) :
 517                                        p2i((address)G1CollectedHeap::heap()->reserved().start()),
 518                    UseCompressedOops ? p2i(CompressedOops::end()) :
 519                                        p2i((address)G1CollectedHeap::heap()->reserved().end()));
 520     log_info(cds)("Dumping objects to closed archive heap region ...");
 521     copy_closed_objects(closed_regions);
 522 
 523     log_info(cds)("Dumping objects to open archive heap region ...");
 524     copy_open_objects(open_regions);
 525 
 526     CDSHeapVerifier::verify();
 527   }
 528 
 529   G1HeapVerifier::verify_archive_regions();
 530 }
 531 
 532 void HeapShared::copy_closed_objects(GrowableArray<MemRegion>* closed_regions) {
 533   assert(HeapShared::can_write(), "must be");
 534 
 535   G1CollectedHeap::heap()->begin_archive_alloc_range();
 536 
 537   // Archive interned string objects
 538   StringTable::write_to_archive(_dumped_interned_strings);
 539 
 540   archive_object_subgraphs(closed_archive_subgraph_entry_fields,
 541                            true /* is_closed_archive */,
 542                            false /* is_full_module_graph */);
 543 
 544   G1CollectedHeap::heap()->end_archive_alloc_range(closed_regions,
 545                                                    os::vm_allocation_granularity());
 546 }
 547 
 548 void HeapShared::copy_open_objects(GrowableArray<MemRegion>* open_regions) {
 549   assert(HeapShared::can_write(), "must be");
 550 
 551   G1CollectedHeap::heap()->begin_archive_alloc_range(true /* open */);
 552 
 553   java_lang_Class::archive_basic_type_mirrors();
 554 
 555   archive_klass_objects();
 556 
 557   archive_object_subgraphs(open_archive_subgraph_entry_fields,
 558                            false /* is_closed_archive */,
 559                            false /* is_full_module_graph */);
 560   if (MetaspaceShared::use_full_module_graph()) {
 561     archive_object_subgraphs(fmg_open_archive_subgraph_entry_fields,
 562                              false /* is_closed_archive */,
 563                              true /* is_full_module_graph */);
 564     Modules::verify_archived_modules();
 565   }
 566 
 567   copy_roots();
 568 
 569   G1CollectedHeap::heap()->end_archive_alloc_range(open_regions,
 570                                                    os::vm_allocation_granularity());
 571 }
 572 
 573 // Copy _pending_archive_roots into an objArray
 574 void HeapShared::copy_roots() {
 575   // HeapShared::roots() points into an ObjArray in the open archive region. A portion of the
 576   // objects in this array are discovered during HeapShared::archive_objects(). For example,
 577   // in HeapShared::archive_reachable_objects_from() ->  HeapShared::check_enum_obj().
 578   // However, HeapShared::archive_objects() happens inside a safepoint, so we can't
 579   // allocate a "regular" ObjArray and pass the result to HeapShared::archive_object().
 580   // Instead, we have to roll our own alloc/copy routine here.
 581   int length = _pending_roots != NULL ? _pending_roots->length() : 0;
 582   size_t size = objArrayOopDesc::object_size(length);
 583   Klass* k = Universe::objectArrayKlassObj(); // already relocated to point to archived klass
 584   HeapWord* mem = G1CollectedHeap::heap()->archive_mem_allocate(size);
 585 
 586   memset(mem, 0, size * BytesPerWord);
 587   {
 588     // This is copied from MemAllocator::finish
 589     oopDesc::set_mark(mem, k->prototype_header());
 590 #ifndef _LP64
 591     oopDesc::release_set_klass(mem, k);
 592 #endif
 593   }
 594   {
 595     // This is copied from ObjArrayAllocator::initialize
 596     arrayOopDesc::set_length(mem, length);
 597   }
 598 
 599   _roots = OopHandle(Universe::vm_global(), cast_to_oop(mem));
 600   for (int i = 0; i < length; i++) {
 601     roots()->obj_at_put(i, _pending_roots->at(i));
 602   }
 603   log_info(cds)("archived obj roots[%d] = " SIZE_FORMAT " words, klass = %p, obj = %p", length, size, k, mem);
 604   count_allocation(roots()->size());
 605 }
 606 
 607 //
 608 // Subgraph archiving support
 609 //
 610 HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = NULL;
 611 HeapShared::RunTimeKlassSubGraphInfoTable   HeapShared::_run_time_subgraph_info_table;
 612 
 613 // Get the subgraph_info for Klass k. A new subgraph_info is created if
 614 // there is no existing one for k. The subgraph_info records the "buffered"
 615 // address of the class.
 616 KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
 617   assert(DumpSharedSpaces, "dump time only");
 618   bool created;
 619   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(k);
 620   KlassSubGraphInfo* info =
 621     _dump_time_subgraph_info_table->put_if_absent(k, KlassSubGraphInfo(buffered_k, is_full_module_graph),
 622                                                   &created);
 623   assert(created, "must not initialize twice");
 624   return info;
 625 }
 626 
 627 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
 628   assert(DumpSharedSpaces, "dump time only");
 629   KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
 630   assert(info != NULL, "must have been initialized");
 631   return info;
 632 }
 633 
 634 // Add an entry field to the current KlassSubGraphInfo.
 635 void KlassSubGraphInfo::add_subgraph_entry_field(
 636       int static_field_offset, oop v, bool is_closed_archive) {
 637   assert(DumpSharedSpaces, "dump time only");
 638   if (_subgraph_entry_fields == NULL) {
 639     _subgraph_entry_fields =
 640       new (mtClass) GrowableArray<int>(10, mtClass);
 641   }
 642   _subgraph_entry_fields->append(static_field_offset);
 643   _subgraph_entry_fields->append(HeapShared::append_root(v));
 644 }
 645 
 646 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
 647 // Only objects of boot classes can be included in sub-graph.
 648 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
 649   assert(DumpSharedSpaces, "dump time only");
 650   Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
 651 
 652   if (_subgraph_object_klasses == NULL) {
 653     _subgraph_object_klasses =
 654       new (mtClass) GrowableArray<Klass*>(50, mtClass);
 655   }
 656 
 657   assert(ArchiveBuilder::current()->is_in_buffer_space(buffered_k), "must be a shared class");
 658 
 659   if (_k == buffered_k) {
 660     // Don't add the Klass containing the sub-graph to it's own klass
 661     // initialization list.
 662     return;
 663   }
 664 
 665   if (buffered_k->is_instance_klass()) {
 666     assert(InstanceKlass::cast(buffered_k)->is_shared_boot_class(),
 667           "must be boot class");
 668     // vmClasses::xxx_klass() are not updated, need to check
 669     // the original Klass*
 670     if (orig_k == vmClasses::String_klass() ||
 671         orig_k == vmClasses::Object_klass()) {
 672       // Initialized early during VM initialization. No need to be added
 673       // to the sub-graph object class list.
 674       return;
 675     }
 676     check_allowed_klass(InstanceKlass::cast(orig_k));
 677   } else if (buffered_k->is_objArray_klass()) {
 678     Klass* abk = ObjArrayKlass::cast(buffered_k)->bottom_klass();
 679     if (abk->is_instance_klass()) {
 680       assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
 681             "must be boot class");
 682       check_allowed_klass(InstanceKlass::cast(ObjArrayKlass::cast(orig_k)->bottom_klass()));
 683     }
 684     if (buffered_k == Universe::objectArrayKlassObj()) {
 685       // Initialized early during Universe::genesis. No need to be added
 686       // to the list.
 687       return;
 688     }
 689   } else {
 690     assert(buffered_k->is_typeArray_klass(), "must be");
 691     // Primitive type arrays are created early during Universe::genesis.
 692     return;
 693   }
 694 
 695   if (log_is_enabled(Debug, cds, heap)) {
 696     if (!_subgraph_object_klasses->contains(buffered_k)) {
 697       ResourceMark rm;
 698       log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
 699     }
 700   }
 701 
 702   _subgraph_object_klasses->append_if_missing(buffered_k);
 703   _has_non_early_klasses |= is_non_early_klass(orig_k);
 704 }
 705 
 706 void KlassSubGraphInfo::check_allowed_klass(InstanceKlass* ik) {
 707   if (ik->module()->name() == vmSymbols::java_base()) {
 708     assert(ik->package() != NULL, "classes in java.base cannot be in unnamed package");
 709     return;
 710   }
 711 
 712 #ifndef PRODUCT
 713   if (!ik->module()->is_named() && ik->package() == NULL) {
 714     // This class is loaded by ArchiveHeapTestClass
 715     return;
 716   }
 717   const char* extra_msg = ", or in an unnamed package of an unnamed module";
 718 #else
 719   const char* extra_msg = "";
 720 #endif
 721 
 722   ResourceMark rm;
 723   log_error(cds, heap)("Class %s not allowed in archive heap. Must be in java.base%s",
 724                        ik->external_name(), extra_msg);
 725   os::_exit(1);
 726 }
 727 
 728 bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
 729   if (k->is_objArray_klass()) {
 730     k = ObjArrayKlass::cast(k)->bottom_klass();
 731   }
 732   if (k->is_instance_klass()) {
 733     if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
 734       ResourceMark rm;
 735       log_info(cds, heap)("non-early: %s", k->external_name());
 736       return true;
 737     } else {
 738       return false;
 739     }
 740   } else {
 741     return false;
 742   }
 743 }
 744 
 745 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
 746 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
 747   _k = info->klass();
 748   _entry_field_records = NULL;
 749   _subgraph_object_klasses = NULL;
 750   _is_full_module_graph = info->is_full_module_graph();
 751 
 752   if (_is_full_module_graph) {
 753     // Consider all classes referenced by the full module graph as early -- we will be
 754     // allocating objects of these classes during JVMTI early phase, so they cannot
 755     // be processed by (non-early) JVMTI ClassFileLoadHook
 756     _has_non_early_klasses = false;
 757   } else {
 758     _has_non_early_klasses = info->has_non_early_klasses();
 759   }
 760 
 761   if (_has_non_early_klasses) {
 762     ResourceMark rm;
 763     log_info(cds, heap)(
 764           "Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
 765           _k->external_name());
 766   }
 767 
 768   // populate the entry fields
 769   GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
 770   if (entry_fields != NULL) {
 771     int num_entry_fields = entry_fields->length();
 772     assert(num_entry_fields % 2 == 0, "sanity");
 773     _entry_field_records =
 774       ArchiveBuilder::new_ro_array<int>(num_entry_fields);
 775     for (int i = 0 ; i < num_entry_fields; i++) {
 776       _entry_field_records->at_put(i, entry_fields->at(i));
 777     }
 778   }
 779 
 780   // the Klasses of the objects in the sub-graphs
 781   GrowableArray<Klass*>* subgraph_object_klasses = info->subgraph_object_klasses();
 782   if (subgraph_object_klasses != NULL) {
 783     int num_subgraphs_klasses = subgraph_object_klasses->length();
 784     _subgraph_object_klasses =
 785       ArchiveBuilder::new_ro_array<Klass*>(num_subgraphs_klasses);
 786     for (int i = 0; i < num_subgraphs_klasses; i++) {
 787       Klass* subgraph_k = subgraph_object_klasses->at(i);
 788       if (log_is_enabled(Info, cds, heap)) {
 789         ResourceMark rm;
 790         log_info(cds, heap)(
 791           "Archived object klass %s (%2d) => %s",
 792           _k->external_name(), i, subgraph_k->external_name());
 793       }
 794       _subgraph_object_klasses->at_put(i, subgraph_k);
 795       ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(i));
 796     }
 797   }
 798 
 799   ArchivePtrMarker::mark_pointer(&_k);
 800   ArchivePtrMarker::mark_pointer(&_entry_field_records);
 801   ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
 802 }
 803 
 804 struct CopyKlassSubGraphInfoToArchive : StackObj {
 805   CompactHashtableWriter* _writer;
 806   CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
 807 
 808   bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
 809     if (info.subgraph_object_klasses() != NULL || info.subgraph_entry_fields() != NULL) {
 810       ArchivedKlassSubGraphInfoRecord* record =
 811         (ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
 812       record->init(&info);
 813 
 814       Klass* buffered_k = ArchiveBuilder::get_buffered_klass(klass);
 815       unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary((address)buffered_k);
 816       u4 delta = ArchiveBuilder::current()->any_to_offset_u4(record);
 817       _writer->add(hash, delta);
 818     }
 819     return true; // keep on iterating
 820   }
 821 };
 822 
 823 // Build the records of archived subgraph infos, which include:
 824 // - Entry points to all subgraphs from the containing class mirror. The entry
 825 //   points are static fields in the mirror. For each entry point, the field
 826 //   offset, value and is_closed_archive flag are recorded in the sub-graph
 827 //   info. The value is stored back to the corresponding field at runtime.
 828 // - A list of klasses that need to be loaded/initialized before archived
 829 //   java object sub-graph can be accessed at runtime.
 830 void HeapShared::write_subgraph_info_table() {
 831   // Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
 832   DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
 833   CompactHashtableStats stats;
 834 
 835   _run_time_subgraph_info_table.reset();
 836 
 837   CompactHashtableWriter writer(d_table->_count, &stats);
 838   CopyKlassSubGraphInfoToArchive copy(&writer);
 839   d_table->iterate(&copy);
 840   writer.dump(&_run_time_subgraph_info_table, "subgraphs");
 841 
 842 #ifndef PRODUCT
 843   if (ArchiveHeapTestClass != NULL) {
 844     size_t len = strlen(ArchiveHeapTestClass) + 1;
 845     Array<char>* array = ArchiveBuilder::new_ro_array<char>((int)len);
 846     strncpy(array->adr_at(0), ArchiveHeapTestClass, len);
 847     _archived_ArchiveHeapTestClass = array;
 848   }
 849 #endif
 850   if (log_is_enabled(Info, cds, heap)) {
 851     print_stats();
 852   }
 853 }
 854 
 855 void HeapShared::serialize_root(SerializeClosure* soc) {
 856   oop roots_oop = NULL;
 857 
 858   if (soc->reading()) {
 859     soc->do_oop(&roots_oop); // read from archive
 860     assert(oopDesc::is_oop_or_null(roots_oop), "is oop");
 861     // Create an OopHandle only if we have actually mapped or loaded the roots
 862     if (roots_oop != NULL) {
 863       assert(ArchiveHeapLoader::is_fully_available(), "must be");
 864       _roots = OopHandle(Universe::vm_global(), roots_oop);
 865     }
 866   } else {
 867     // writing
 868     roots_oop = roots();
 869     soc->do_oop(&roots_oop); // write to archive
 870   }
 871 }
 872 
 873 void HeapShared::serialize_tables(SerializeClosure* soc) {
 874 
 875 #ifndef PRODUCT
 876   soc->do_ptr((void**)&_archived_ArchiveHeapTestClass);
 877   if (soc->reading() && _archived_ArchiveHeapTestClass != NULL) {
 878     _test_class_name = _archived_ArchiveHeapTestClass->adr_at(0);
 879     setup_test_class(_test_class_name);
 880   }
 881 #endif
 882 
 883   _run_time_subgraph_info_table.serialize_header(soc);
 884 }
 885 
 886 static void verify_the_heap(Klass* k, const char* which) {
 887   if (VerifyArchivedFields > 0) {
 888     ResourceMark rm;
 889     log_info(cds, heap)("Verify heap %s initializing static field(s) in %s",
 890                         which, k->external_name());
 891 
 892     VM_Verify verify_op;
 893     VMThread::execute(&verify_op);
 894 
 895     if (VerifyArchivedFields > 1 && is_init_completed()) {
 896       // At this time, the oop->klass() of some archived objects in the heap may not
 897       // have been loaded into the system dictionary yet. Nevertheless, oop->klass() should
 898       // have enough information (object size, oop maps, etc) so that a GC can be safely
 899       // performed.
 900       //
 901       // -XX:VerifyArchivedFields=2 force a GC to happen in such an early stage
 902       // to check for GC safety.
 903       log_info(cds, heap)("Trigger GC %s initializing static field(s) in %s",
 904                           which, k->external_name());
 905       FlagSetting fs1(VerifyBeforeGC, true);
 906       FlagSetting fs2(VerifyDuringGC, true);
 907       FlagSetting fs3(VerifyAfterGC,  true);
 908       Universe::heap()->collect(GCCause::_java_lang_system_gc);
 909     }
 910   }
 911 }
 912 
 913 // Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
 914 // have a valid klass. I.e., oopDesc::klass() must have already been resolved.
 915 //
 916 // Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
 917 // ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
 918 // this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
 919 void HeapShared::resolve_classes(JavaThread* current) {
 920   assert(UseSharedSpaces, "runtime only!");
 921   if (!ArchiveHeapLoader::is_fully_available()) {
 922     return; // nothing to do
 923   }
 924   resolve_classes_for_subgraphs(current, closed_archive_subgraph_entry_fields);
 925   resolve_classes_for_subgraphs(current, open_archive_subgraph_entry_fields);
 926   resolve_classes_for_subgraphs(current, fmg_open_archive_subgraph_entry_fields);
 927 }
 928 
 929 void HeapShared::resolve_classes_for_subgraphs(JavaThread* current, ArchivableStaticFieldInfo fields[]) {
 930   for (int i = 0; fields[i].valid(); i++) {
 931     ArchivableStaticFieldInfo* info = &fields[i];
 932     TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
 933     InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
 934     assert(k != NULL && k->is_shared_boot_class(), "sanity");
 935     resolve_classes_for_subgraph_of(current, k);
 936   }
 937 }
 938 
 939 void HeapShared::resolve_classes_for_subgraph_of(JavaThread* current, Klass* k) {
 940   JavaThread* THREAD = current;
 941   ExceptionMark em(THREAD);
 942   const ArchivedKlassSubGraphInfoRecord* record =
 943    resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
 944   if (HAS_PENDING_EXCEPTION) {
 945    CLEAR_PENDING_EXCEPTION;
 946   }
 947   if (record == NULL) {
 948    clear_archived_roots_of(k);
 949   }
 950 }
 951 
 952 void HeapShared::initialize_from_archived_subgraph(JavaThread* current, Klass* k) {
 953   JavaThread* THREAD = current;
 954   if (!ArchiveHeapLoader::is_fully_available()) {
 955     return; // nothing to do
 956   }
 957 
 958   ExceptionMark em(THREAD);
 959   const ArchivedKlassSubGraphInfoRecord* record =
 960     resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
 961 
 962   if (HAS_PENDING_EXCEPTION) {
 963     CLEAR_PENDING_EXCEPTION;
 964     // None of the field value will be set if there was an exception when initializing the classes.
 965     // The java code will not see any of the archived objects in the
 966     // subgraphs referenced from k in this case.
 967     return;
 968   }
 969 
 970   if (record != NULL) {
 971     init_archived_fields_for(k, record);
 972   }
 973 }
 974 
 975 const ArchivedKlassSubGraphInfoRecord*
 976 HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
 977   assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
 978 
 979   if (!k->is_shared()) {
 980     return NULL;
 981   }
 982   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
 983   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
 984 
 985 #ifndef PRODUCT
 986   if (_test_class_name != NULL && k->name()->equals(_test_class_name) && record != NULL) {
 987     _test_class = k;
 988     _test_class_record = record;
 989   }
 990 #endif
 991 
 992   // Initialize from archived data. Currently this is done only
 993   // during VM initialization time. No lock is needed.
 994   if (record != NULL) {
 995     if (record->is_full_module_graph() && !MetaspaceShared::use_full_module_graph()) {
 996       if (log_is_enabled(Info, cds, heap)) {
 997         ResourceMark rm(THREAD);
 998         log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
 999                             k->external_name());
1000       }
1001       return NULL;
1002     }
1003 
1004     if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
1005       if (log_is_enabled(Info, cds, heap)) {
1006         ResourceMark rm(THREAD);
1007         log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
1008                             k->external_name());
1009       }
1010       return NULL;
1011     }
1012 
1013     if (log_is_enabled(Info, cds, heap)) {
1014       ResourceMark rm;
1015       log_info(cds, heap)("%s subgraph %s ", do_init ? "init" : "resolve", k->external_name());
1016     }
1017 
1018     resolve_or_init(k, do_init, CHECK_NULL);
1019 
1020     // Load/link/initialize the klasses of the objects in the subgraph.
1021     // NULL class loader is used.
1022     Array<Klass*>* klasses = record->subgraph_object_klasses();
1023     if (klasses != NULL) {
1024       for (int i = 0; i < klasses->length(); i++) {
1025         Klass* klass = klasses->at(i);
1026         if (!klass->is_shared()) {
1027           return NULL;
1028         }
1029         resolve_or_init(klass, do_init, CHECK_NULL);
1030       }
1031     }
1032   }
1033 
1034   return record;
1035 }
1036 
1037 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
1038   if (!do_init) {
1039     if (k->class_loader_data() == NULL) {
1040       Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
1041       assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
1042     }
1043   } else {
1044     assert(k->class_loader_data() != NULL, "must have been resolved by HeapShared::resolve_classes");
1045     if (k->is_instance_klass()) {
1046       InstanceKlass* ik = InstanceKlass::cast(k);
1047       ik->initialize(CHECK);
1048     } else if (k->is_objArray_klass()) {
1049       ObjArrayKlass* oak = ObjArrayKlass::cast(k);
1050       oak->initialize(CHECK);
1051     }
1052   }
1053 }
1054 
1055 void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record) {
1056   verify_the_heap(k, "before");
1057 
1058   // Load the subgraph entry fields from the record and store them back to
1059   // the corresponding fields within the mirror.
1060   oop m = k->java_mirror();
1061   Array<int>* entry_field_records = record->entry_field_records();
1062   if (entry_field_records != NULL) {
1063     int efr_len = entry_field_records->length();
1064     assert(efr_len % 2 == 0, "sanity");
1065     for (int i = 0; i < efr_len; i += 2) {
1066       int field_offset = entry_field_records->at(i);
1067       int root_index = entry_field_records->at(i+1);
1068       oop v = get_root(root_index, /*clear=*/true);
1069       m->obj_field_put(field_offset, v);
1070       log_debug(cds, heap)("  " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
1071     }
1072 
1073     // Done. Java code can see the archived sub-graphs referenced from k's
1074     // mirror after this point.
1075     if (log_is_enabled(Info, cds, heap)) {
1076       ResourceMark rm;
1077       log_info(cds, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s",
1078                           k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "");
1079     }
1080   }
1081 
1082   verify_the_heap(k, "after ");
1083 }
1084 
1085 void HeapShared::clear_archived_roots_of(Klass* k) {
1086   unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
1087   const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
1088   if (record != NULL) {
1089     Array<int>* entry_field_records = record->entry_field_records();
1090     if (entry_field_records != NULL) {
1091       int efr_len = entry_field_records->length();
1092       assert(efr_len % 2 == 0, "sanity");
1093       for (int i = 0; i < efr_len; i += 2) {
1094         int root_index = entry_field_records->at(i+1);
1095         clear_root(root_index);
1096       }
1097     }
1098   }
1099 }
1100 
1101 class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
1102   int _level;
1103   bool _is_closed_archive;
1104   bool _record_klasses_only;
1105   KlassSubGraphInfo* _subgraph_info;
1106   oop _orig_referencing_obj;
1107   oop _archived_referencing_obj;
1108 
1109   // The following are for maintaining a stack for determining
1110   // CachedOopInfo::_referrer
1111   static WalkOopAndArchiveClosure* _current;
1112   WalkOopAndArchiveClosure* _last;
1113  public:
1114   WalkOopAndArchiveClosure(int level,
1115                            bool is_closed_archive,
1116                            bool record_klasses_only,
1117                            KlassSubGraphInfo* subgraph_info,
1118                            oop orig, oop archived) :
1119     _level(level), _is_closed_archive(is_closed_archive),
1120     _record_klasses_only(record_klasses_only),
1121     _subgraph_info(subgraph_info),
1122     _orig_referencing_obj(orig), _archived_referencing_obj(archived) {
1123     _last = _current;
1124     _current = this;
1125   }
1126   ~WalkOopAndArchiveClosure() {
1127     _current = _last;
1128   }
1129   void do_oop(narrowOop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
1130   void do_oop(      oop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
1131 
1132  protected:
1133   template <class T> void do_oop_work(T *p) {
1134     oop obj = RawAccess<>::oop_load(p);
1135     if (!CompressedOops::is_null(obj)) {
1136       assert(!HeapShared::is_archived_object_during_dumptime(obj),
1137              "original objects must not point to archived objects");
1138 
1139       size_t field_delta = pointer_delta(p, _orig_referencing_obj, sizeof(char));
1140       T* new_p = (T*)(cast_from_oop<address>(_archived_referencing_obj) + field_delta);
1141 
1142       if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
1143         ResourceMark rm;
1144         log_debug(cds, heap)("(%d) %s[" SIZE_FORMAT "] ==> " PTR_FORMAT " size " SIZE_FORMAT " %s", _level,
1145                              _orig_referencing_obj->klass()->external_name(), field_delta,
1146                              p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
1147         LogTarget(Trace, cds, heap) log;
1148         LogStream out(log);
1149         obj->print_on(&out);
1150       }
1151 
1152       oop archived = HeapShared::archive_reachable_objects_from(
1153           _level + 1, _subgraph_info, obj, _is_closed_archive);
1154       assert(archived != NULL, "VM should have exited with unarchivable objects for _level > 1");
1155       assert(HeapShared::is_archived_object_during_dumptime(archived), "must be");
1156 
1157       if (!_record_klasses_only) {
1158         // Update the reference in the archived copy of the referencing object.
1159         log_debug(cds, heap)("(%d) updating oop @[" PTR_FORMAT "] " PTR_FORMAT " ==> " PTR_FORMAT,
1160                              _level, p2i(new_p), p2i(obj), p2i(archived));
1161         RawAccess<IS_NOT_NULL>::oop_store(new_p, archived);
1162       }
1163     }
1164   }
1165 
1166  public:
1167   static WalkOopAndArchiveClosure* current()  { return _current;              }
1168   oop orig_referencing_obj()                  { return _orig_referencing_obj; }
1169   KlassSubGraphInfo* subgraph_info()          { return _subgraph_info;        }
1170 };
1171 
1172 WalkOopAndArchiveClosure* WalkOopAndArchiveClosure::_current = NULL;
1173 
1174 HeapShared::CachedOopInfo HeapShared::make_cached_oop_info(oop orig_obj) {
1175   CachedOopInfo info;
1176   WalkOopAndArchiveClosure* walker = WalkOopAndArchiveClosure::current();
1177 
1178   info._subgraph_info = (walker == NULL) ? NULL : walker->subgraph_info();
1179   info._referrer = (walker == NULL) ? NULL : walker->orig_referencing_obj();
1180   info._obj = orig_obj;
1181 
1182   return info;
1183 }
1184 
1185 void HeapShared::check_closed_region_object(InstanceKlass* k) {
1186   // Check fields in the object
1187   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
1188     if (!fs.access_flags().is_static()) {
1189       BasicType ft = fs.field_descriptor().field_type();
1190       if (!fs.access_flags().is_final() && is_reference_type(ft)) {
1191         ResourceMark rm;
1192         log_warning(cds, heap)(
1193           "Please check reference field in %s instance in closed archive heap region: %s %s",
1194           k->external_name(), (fs.name())->as_C_string(),
1195           (fs.signature())->as_C_string());
1196       }
1197     }
1198   }
1199 }
1200 
1201 // (1) If orig_obj has not been archived yet, archive it.
1202 // (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
1203 //     trace all  objects that are reachable from it, and make sure these objects are archived.
1204 // (3) Record the klasses of all orig_obj and all reachable objects.
1205 oop HeapShared::archive_reachable_objects_from(int level,
1206                                                KlassSubGraphInfo* subgraph_info,
1207                                                oop orig_obj,
1208                                                bool is_closed_archive) {
1209   assert(orig_obj != NULL, "must be");
1210   assert(!is_archived_object_during_dumptime(orig_obj), "sanity");
1211 
1212   if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
1213     // This object has injected fields that cannot be supported easily, so we disallow them for now.
1214     // If you get an error here, you probably made a change in the JDK library that has added
1215     // these objects that are referenced (directly or indirectly) by static fields.
1216     ResourceMark rm;
1217     log_error(cds, heap)("Cannot archive object of class %s", orig_obj->klass()->external_name());
1218     os::_exit(1);
1219   }
1220 
1221   // java.lang.Class instances cannot be included in an archived object sub-graph. We only support
1222   // them as Klass::_archived_mirror because they need to be specially restored at run time.
1223   //
1224   // If you get an error here, you probably made a change in the JDK library that has added a Class
1225   // object that is referenced (directly or indirectly) by static fields.
1226   if (java_lang_Class::is_instance(orig_obj)) {
1227     log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
1228     os::_exit(1);
1229   }
1230 
1231   oop archived_obj = find_archived_heap_object(orig_obj);
1232   if (java_lang_String::is_instance(orig_obj) && archived_obj != NULL) {
1233     // To save time, don't walk strings that are already archived. They just contain
1234     // pointers to a type array, whose klass doesn't need to be recorded.
1235     return archived_obj;
1236   }
1237 
1238   if (has_been_seen_during_subgraph_recording(orig_obj)) {
1239     // orig_obj has already been archived and traced. Nothing more to do.
1240     return archived_obj;
1241   } else {
1242     set_has_been_seen_during_subgraph_recording(orig_obj);
1243   }
1244 
1245   bool record_klasses_only = (archived_obj != NULL);
1246   if (archived_obj == NULL) {
1247     ++_num_new_archived_objs;
1248     archived_obj = archive_object(orig_obj);
1249     if (archived_obj == NULL) {
1250       // Skip archiving the sub-graph referenced from the current entry field.
1251       ResourceMark rm;
1252       log_error(cds, heap)(
1253         "Cannot archive the sub-graph referenced from %s object ("
1254         PTR_FORMAT ") size " SIZE_FORMAT ", skipped.",
1255         orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
1256       if (level == 1) {
1257         // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1258         // as the Java code will take care of initializing this field dynamically.
1259         return NULL;
1260       } else {
1261         // We don't know how to handle an object that has been archived, but some of its reachable
1262         // objects cannot be archived. Bail out for now. We might need to fix this in the future if
1263         // we have a real use case.
1264         os::_exit(1);
1265       }
1266     }
1267 
1268     if (java_lang_Module::is_instance(orig_obj)) {
1269       if (Modules::check_module_oop(orig_obj)) {
1270         Modules::update_oops_in_archived_module(orig_obj, append_root(archived_obj));
1271       }
1272       java_lang_Module::set_module_entry(archived_obj, NULL);
1273     } else if (java_lang_ClassLoader::is_instance(orig_obj)) {
1274       // class_data will be restored explicitly at run time.
1275       guarantee(orig_obj == SystemDictionary::java_platform_loader() ||
1276                 orig_obj == SystemDictionary::java_system_loader() ||
1277                 java_lang_ClassLoader::loader_data(orig_obj) == NULL, "must be");
1278       java_lang_ClassLoader::release_set_loader_data(archived_obj, NULL);
1279     }
1280   }
1281 
1282   assert(archived_obj != NULL, "must be");
1283   Klass *orig_k = orig_obj->klass();
1284   subgraph_info->add_subgraph_object_klass(orig_k);
1285 
1286   WalkOopAndArchiveClosure walker(level, is_closed_archive, record_klasses_only,
1287                                   subgraph_info, orig_obj, archived_obj);
1288   orig_obj->oop_iterate(&walker);
1289   if (is_closed_archive && orig_k->is_instance_klass()) {
1290     check_closed_region_object(InstanceKlass::cast(orig_k));
1291   }
1292 
1293   check_enum_obj(level + 1, subgraph_info, orig_obj, is_closed_archive);
1294   return archived_obj;
1295 }
1296 
1297 //
1298 // Start from the given static field in a java mirror and archive the
1299 // complete sub-graph of java heap objects that are reached directly
1300 // or indirectly from the starting object by following references.
1301 // Sub-graph archiving restrictions (current):
1302 //
1303 // - All classes of objects in the archived sub-graph (including the
1304 //   entry class) must be boot class only.
1305 // - No java.lang.Class instance (java mirror) can be included inside
1306 //   an archived sub-graph. Mirror can only be the sub-graph entry object.
1307 //
1308 // The Java heap object sub-graph archiving process (see
1309 // WalkOopAndArchiveClosure):
1310 //
1311 // 1) Java object sub-graph archiving starts from a given static field
1312 // within a Class instance (java mirror). If the static field is a
1313 // reference field and points to a non-null java object, proceed to
1314 // the next step.
1315 //
1316 // 2) Archives the referenced java object. If an archived copy of the
1317 // current object already exists, updates the pointer in the archived
1318 // copy of the referencing object to point to the current archived object.
1319 // Otherwise, proceed to the next step.
1320 //
1321 // 3) Follows all references within the current java object and recursively
1322 // archive the sub-graph of objects starting from each reference.
1323 //
1324 // 4) Updates the pointer in the archived copy of referencing object to
1325 // point to the current archived object.
1326 //
1327 // 5) The Klass of the current java object is added to the list of Klasses
1328 // for loading and initializing before any object in the archived graph can
1329 // be accessed at runtime.
1330 //
1331 void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
1332                                                              const char* klass_name,
1333                                                              int field_offset,
1334                                                              const char* field_name,
1335                                                              bool is_closed_archive) {
1336   assert(DumpSharedSpaces, "dump time only");
1337   assert(k->is_shared_boot_class(), "must be boot class");
1338 
1339   oop m = k->java_mirror();
1340 
1341   KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
1342   oop f = m->obj_field(field_offset);
1343 
1344   log_debug(cds, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
1345 
1346   if (!CompressedOops::is_null(f)) {
1347     if (log_is_enabled(Trace, cds, heap)) {
1348       LogTarget(Trace, cds, heap) log;
1349       LogStream out(log);
1350       f->print_on(&out);
1351     }
1352 
1353     oop af = archive_reachable_objects_from(1, subgraph_info, f, is_closed_archive);
1354 
1355     if (af == NULL) {
1356       log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
1357                            klass_name, field_name);
1358     } else {
1359       // Note: the field value is not preserved in the archived mirror.
1360       // Record the field as a new subGraph entry point. The recorded
1361       // information is restored from the archive at runtime.
1362       subgraph_info->add_subgraph_entry_field(field_offset, af, is_closed_archive);
1363       log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(af));
1364     }
1365   } else {
1366     // The field contains null, we still need to record the entry point,
1367     // so it can be restored at runtime.
1368     subgraph_info->add_subgraph_entry_field(field_offset, NULL, false);
1369   }
1370 }
1371 
1372 #ifndef PRODUCT
1373 class VerifySharedOopClosure: public BasicOopIterateClosure {
1374  private:
1375   bool _is_archived;
1376 
1377  public:
1378   VerifySharedOopClosure(bool is_archived) : _is_archived(is_archived) {}
1379 
1380   void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
1381   void do_oop(      oop *p) { VerifySharedOopClosure::do_oop_work(p); }
1382 
1383  protected:
1384   template <class T> void do_oop_work(T *p) {
1385     oop obj = RawAccess<>::oop_load(p);
1386     if (!CompressedOops::is_null(obj)) {
1387       HeapShared::verify_reachable_objects_from(obj, _is_archived);
1388     }
1389   }
1390 };
1391 
1392 void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
1393   assert(DumpSharedSpaces, "dump time only");
1394   assert(k->is_shared_boot_class(), "must be boot class");
1395 
1396   oop m = k->java_mirror();
1397   oop f = m->obj_field(field_offset);
1398   if (!CompressedOops::is_null(f)) {
1399     verify_subgraph_from(f);
1400   }
1401 }
1402 
1403 void HeapShared::verify_subgraph_from(oop orig_obj) {
1404   oop archived_obj = find_archived_heap_object(orig_obj);
1405   if (archived_obj == NULL) {
1406     // It's OK for the root of a subgraph to be not archived. See comments in
1407     // archive_reachable_objects_from().
1408     return;
1409   }
1410 
1411   // Verify that all objects reachable from orig_obj are archived.
1412   init_seen_objects_table();
1413   verify_reachable_objects_from(orig_obj, false);
1414   delete_seen_objects_table();
1415 
1416   // Note: we could also verify that all objects reachable from the archived
1417   // copy of orig_obj can only point to archived objects, with:
1418   //      init_seen_objects_table();
1419   //      verify_reachable_objects_from(archived_obj, true);
1420   //      init_seen_objects_table();
1421   // but that's already done in G1HeapVerifier::verify_archive_regions so we
1422   // won't do it here.
1423 }
1424 
1425 void HeapShared::verify_reachable_objects_from(oop obj, bool is_archived) {
1426   _num_total_verifications ++;
1427   if (!has_been_seen_during_subgraph_recording(obj)) {
1428     set_has_been_seen_during_subgraph_recording(obj);
1429 
1430     if (is_archived) {
1431       assert(is_archived_object_during_dumptime(obj), "must be");
1432       assert(find_archived_heap_object(obj) == NULL, "must be");
1433     } else {
1434       assert(!is_archived_object_during_dumptime(obj), "must be");
1435       assert(find_archived_heap_object(obj) != NULL, "must be");
1436     }
1437 
1438     VerifySharedOopClosure walker(is_archived);
1439     obj->oop_iterate(&walker);
1440   }
1441 }
1442 #endif
1443 
1444 HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = NULL;
1445 int HeapShared::_num_new_walked_objs;
1446 int HeapShared::_num_new_archived_objs;
1447 int HeapShared::_num_old_recorded_klasses;
1448 
1449 int HeapShared::_num_total_subgraph_recordings = 0;
1450 int HeapShared::_num_total_walked_objs = 0;
1451 int HeapShared::_num_total_archived_objs = 0;
1452 int HeapShared::_num_total_recorded_klasses = 0;
1453 int HeapShared::_num_total_verifications = 0;
1454 
1455 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
1456   return _seen_objects_table->get(obj) != NULL;
1457 }
1458 
1459 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
1460   assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
1461   _seen_objects_table->put(obj, true);
1462   ++ _num_new_walked_objs;
1463 }
1464 
1465 void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
1466   log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
1467   init_subgraph_info(k, is_full_module_graph);
1468   init_seen_objects_table();
1469   _num_new_walked_objs = 0;
1470   _num_new_archived_objs = 0;
1471   _num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
1472 }
1473 
1474 void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
1475   int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
1476     _num_old_recorded_klasses;
1477   log_info(cds, heap)("Done recording subgraph(s) for archived fields in %s: "
1478                       "walked %d objs, archived %d new objs, recorded %d classes",
1479                       class_name, _num_new_walked_objs, _num_new_archived_objs,
1480                       num_new_recorded_klasses);
1481 
1482   delete_seen_objects_table();
1483 
1484   _num_total_subgraph_recordings ++;
1485   _num_total_walked_objs      += _num_new_walked_objs;
1486   _num_total_archived_objs    += _num_new_archived_objs;
1487   _num_total_recorded_klasses +=  num_new_recorded_klasses;
1488 }
1489 
1490 class ArchivableStaticFieldFinder: public FieldClosure {
1491   InstanceKlass* _ik;
1492   Symbol* _field_name;
1493   bool _found;
1494   int _offset;
1495 public:
1496   ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
1497     _ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
1498 
1499   virtual void do_field(fieldDescriptor* fd) {
1500     if (fd->name() == _field_name) {
1501       assert(!_found, "fields can never be overloaded");
1502       if (is_reference_type(fd->field_type())) {
1503         _found = true;
1504         _offset = fd->offset();
1505       }
1506     }
1507   }
1508   bool found()     { return _found;  }
1509   int offset()     { return _offset; }
1510 };
1511 
1512 void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
1513                                             TRAPS) {
1514   for (int i = 0; fields[i].valid(); i++) {
1515     ArchivableStaticFieldInfo* info = &fields[i];
1516     TempNewSymbol klass_name =  SymbolTable::new_symbol(info->klass_name);
1517     TempNewSymbol field_name =  SymbolTable::new_symbol(info->field_name);
1518     ResourceMark rm; // for stringStream::as_string() etc.
1519 
1520 #ifndef PRODUCT
1521     bool is_test_class = (ArchiveHeapTestClass != NULL) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
1522 #else
1523     bool is_test_class = false;
1524 #endif
1525 
1526     if (is_test_class) {
1527       log_warning(cds)("Loading ArchiveHeapTestClass %s ...", ArchiveHeapTestClass);
1528     }
1529 
1530     Klass* k = SystemDictionary::resolve_or_fail(klass_name, true, THREAD);
1531     if (HAS_PENDING_EXCEPTION) {
1532       CLEAR_PENDING_EXCEPTION;
1533       stringStream st;
1534       st.print("Fail to initialize archive heap: %s cannot be loaded by the boot loader", info->klass_name);
1535       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1536     }
1537 
1538     if (!k->is_instance_klass()) {
1539       stringStream st;
1540       st.print("Fail to initialize archive heap: %s is not an instance class", info->klass_name);
1541       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1542     }
1543 
1544     InstanceKlass* ik = InstanceKlass::cast(k);
1545     assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
1546            "Only support boot classes");
1547 
1548     if (is_test_class) {
1549       if (ik->module()->is_named()) {
1550         // We don't want ArchiveHeapTestClass to be abused to easily load/initialize arbitrary
1551         // core-lib classes. You need to at least append to the bootclasspath.
1552         stringStream st;
1553         st.print("ArchiveHeapTestClass %s is not in unnamed module", ArchiveHeapTestClass);
1554         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1555       }
1556 
1557       if (ik->package() != NULL) {
1558         // This restriction makes HeapShared::is_a_test_class_in_unnamed_module() easy.
1559         stringStream st;
1560         st.print("ArchiveHeapTestClass %s is not in unnamed package", ArchiveHeapTestClass);
1561         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1562       }
1563     } else {
1564       if (ik->module()->name() != vmSymbols::java_base()) {
1565         // We don't want to deal with cases when a module is unavailable at runtime.
1566         // FUTURE -- load from archived heap only when module graph has not changed
1567         //           between dump and runtime.
1568         stringStream st;
1569         st.print("%s is not in java.base module", info->klass_name);
1570         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1571       }
1572     }
1573 
1574     if (is_test_class) {
1575       log_warning(cds)("Initializing ArchiveHeapTestClass %s ...", ArchiveHeapTestClass);
1576     }
1577     ik->initialize(CHECK);
1578 
1579     ArchivableStaticFieldFinder finder(ik, field_name);
1580     ik->do_local_static_fields(&finder);
1581     if (!finder.found()) {
1582       stringStream st;
1583       st.print("Unable to find the static T_OBJECT field %s::%s", info->klass_name, info->field_name);
1584       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1585     }
1586 
1587     info->klass = ik;
1588     info->offset = finder.offset();
1589   }
1590 }
1591 
1592 void HeapShared::init_subgraph_entry_fields(TRAPS) {
1593   assert(HeapShared::can_write(), "must be");
1594   _dump_time_subgraph_info_table = new (mtClass)DumpTimeKlassSubGraphInfoTable();
1595   init_subgraph_entry_fields(closed_archive_subgraph_entry_fields, CHECK);
1596   init_subgraph_entry_fields(open_archive_subgraph_entry_fields, CHECK);
1597   if (MetaspaceShared::use_full_module_graph()) {
1598     init_subgraph_entry_fields(fmg_open_archive_subgraph_entry_fields, CHECK);
1599   }
1600 }
1601 
1602 #ifndef PRODUCT
1603 void HeapShared::setup_test_class(const char* test_class_name) {
1604   ArchivableStaticFieldInfo* p = open_archive_subgraph_entry_fields;
1605   int num_slots = sizeof(open_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
1606   assert(p[num_slots - 2].klass_name == NULL, "must have empty slot that's patched below");
1607   assert(p[num_slots - 1].klass_name == NULL, "must have empty slot that marks the end of the list");
1608 
1609   if (test_class_name != NULL) {
1610     p[num_slots - 2].klass_name = test_class_name;
1611     p[num_slots - 2].field_name = ARCHIVE_TEST_FIELD_NAME;
1612   }
1613 }
1614 
1615 // See if ik is one of the test classes that are pulled in by -XX:ArchiveHeapTestClass
1616 // during runtime. This may be called before the module system is initialized so
1617 // we cannot rely on InstanceKlass::module(), etc.
1618 bool HeapShared::is_a_test_class_in_unnamed_module(Klass* ik) {
1619   if (_test_class != NULL) {
1620     if (ik == _test_class) {
1621       return true;
1622     }
1623     Array<Klass*>* klasses = _test_class_record->subgraph_object_klasses();
1624     if (klasses == NULL) {
1625       return false;
1626     }
1627 
1628     for (int i = 0; i < klasses->length(); i++) {
1629       Klass* k = klasses->at(i);
1630       if (k == ik) {
1631         Symbol* name;
1632         if (k->is_instance_klass()) {
1633           name = InstanceKlass::cast(k)->name();
1634         } else if (k->is_objArray_klass()) {
1635           Klass* bk = ObjArrayKlass::cast(k)->bottom_klass();
1636           if (!bk->is_instance_klass()) {
1637             return false;
1638           }
1639           name = bk->name();
1640         } else {
1641           return false;
1642         }
1643 
1644         // See KlassSubGraphInfo::check_allowed_klass() - only two types of
1645         // classes are allowed:
1646         //   (A) java.base classes (which must not be in the unnamed module)
1647         //   (B) test classes which must be in the unnamed package of the unnamed module.
1648         // So if we see a '/' character in the class name, it must be in (A);
1649         // otherwise it must be in (B).
1650         if (name->index_of_at(0, "/", 1)  >= 0) {
1651           return false; // (A)
1652         }
1653 
1654         return true; // (B)
1655       }
1656     }
1657   }
1658 
1659   return false;
1660 }
1661 #endif
1662 
1663 void HeapShared::init_for_dumping(TRAPS) {
1664   if (HeapShared::can_write()) {
1665     setup_test_class(ArchiveHeapTestClass);
1666     _dumped_interned_strings = new (mtClass)DumpedInternedStrings();
1667     _native_pointers = new GrowableArrayCHeap<Metadata**, mtClassShared>(2048);
1668     init_subgraph_entry_fields(CHECK);
1669   }
1670 }
1671 
1672 void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
1673                                           bool is_closed_archive,
1674                                           bool is_full_module_graph) {
1675   _num_total_subgraph_recordings = 0;
1676   _num_total_walked_objs = 0;
1677   _num_total_archived_objs = 0;
1678   _num_total_recorded_klasses = 0;
1679   _num_total_verifications = 0;
1680 
1681   // For each class X that has one or more archived fields:
1682   // [1] Dump the subgraph of each archived field
1683   // [2] Create a list of all the class of the objects that can be reached
1684   //     by any of these static fields.
1685   //     At runtime, these classes are initialized before X's archived fields
1686   //     are restored by HeapShared::initialize_from_archived_subgraph().
1687   int i;
1688   for (int i = 0; fields[i].valid(); ) {
1689     ArchivableStaticFieldInfo* info = &fields[i];
1690     const char* klass_name = info->klass_name;
1691     start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
1692 
1693     // If you have specified consecutive fields of the same klass in
1694     // fields[], these will be archived in the same
1695     // {start_recording_subgraph ... done_recording_subgraph} pass to
1696     // save time.
1697     for (; fields[i].valid(); i++) {
1698       ArchivableStaticFieldInfo* f = &fields[i];
1699       if (f->klass_name != klass_name) {
1700         break;
1701       }
1702 
1703       archive_reachable_objects_from_static_field(f->klass, f->klass_name,
1704                                                   f->offset, f->field_name,
1705                                                   is_closed_archive);
1706     }
1707     done_recording_subgraph(info->klass, klass_name);
1708   }
1709 
1710   log_info(cds, heap)("Archived subgraph records in %s archive heap region = %d",
1711                       is_closed_archive ? "closed" : "open",
1712                       _num_total_subgraph_recordings);
1713   log_info(cds, heap)("  Walked %d objects", _num_total_walked_objs);
1714   log_info(cds, heap)("  Archived %d objects", _num_total_archived_objs);
1715   log_info(cds, heap)("  Recorded %d klasses", _num_total_recorded_klasses);
1716 
1717 #ifndef PRODUCT
1718   for (int i = 0; fields[i].valid(); i++) {
1719     ArchivableStaticFieldInfo* f = &fields[i];
1720     verify_subgraph_from_static_field(f->klass, f->offset);
1721   }
1722   log_info(cds, heap)("  Verified %d references", _num_total_verifications);
1723 #endif
1724 }
1725 
1726 // Not all the strings in the global StringTable are dumped into the archive, because
1727 // some of those strings may be only referenced by classes that are excluded from
1728 // the archive. We need to explicitly mark the strings that are:
1729 //   [1] used by classes that WILL be archived;
1730 //   [2] included in the SharedArchiveConfigFile.
1731 void HeapShared::add_to_dumped_interned_strings(oop string) {
1732   assert_at_safepoint(); // DumpedInternedStrings uses raw oops
1733   bool created;
1734   _dumped_interned_strings->put_if_absent(string, true, &created);
1735 }
1736 
1737 // At dump-time, find the location of all the non-null oop pointers in an archived heap
1738 // region. This way we can quickly relocate all the pointers without using
1739 // BasicOopIterateClosure at runtime.
1740 class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
1741   void* _start;
1742   BitMap *_oopmap;
1743   int _num_total_oops;
1744   int _num_null_oops;
1745  public:
1746   FindEmbeddedNonNullPointers(void* start, BitMap* oopmap)
1747     : _start(start), _oopmap(oopmap), _num_total_oops(0),  _num_null_oops(0) {}
1748 
1749   virtual void do_oop(narrowOop* p) {
1750     assert(UseCompressedOops, "sanity");
1751     _num_total_oops ++;
1752     narrowOop v = *p;
1753     if (!CompressedOops::is_null(v)) {
1754       // Note: HeapShared::to_requested_address() is not necessary because
1755       // the heap always starts at a deterministic address with UseCompressedOops==true.
1756       size_t idx = p - (narrowOop*)_start;
1757       _oopmap->set_bit(idx);
1758     } else {
1759       _num_null_oops ++;
1760     }
1761   }
1762   virtual void do_oop(oop* p) {
1763     assert(!UseCompressedOops, "sanity");
1764     _num_total_oops ++;
1765     if ((*p) != NULL) {
1766       size_t idx = p - (oop*)_start;
1767       _oopmap->set_bit(idx);
1768       if (DumpSharedSpaces) {
1769         // Make heap content deterministic.
1770         *p = HeapShared::to_requested_address(*p);
1771       }
1772     } else {
1773       _num_null_oops ++;
1774     }
1775   }
1776   int num_total_oops() const { return _num_total_oops; }
1777   int num_null_oops()  const { return _num_null_oops; }
1778 };
1779 
1780 
1781 address HeapShared::to_requested_address(address dumptime_addr) {
1782   assert(DumpSharedSpaces, "static dump time only");
1783   if (dumptime_addr == NULL || UseCompressedOops) {
1784     return dumptime_addr;
1785   }
1786 
1787   // With UseCompressedOops==false, actual_base is selected by the OS so
1788   // it's different across -Xshare:dump runs.
1789   address actual_base = (address)G1CollectedHeap::heap()->reserved().start();
1790   address actual_end  = (address)G1CollectedHeap::heap()->reserved().end();
1791   assert(actual_base <= dumptime_addr && dumptime_addr <= actual_end, "must be an address in the heap");
1792 
1793   // We always write the objects as if the heap started at this address. This
1794   // makes the heap content deterministic.
1795   //
1796   // Note that at runtime, the heap address is also selected by the OS, so
1797   // the archive heap will not be mapped at 0x10000000. Instead, we will call
1798   // HeapShared::patch_embedded_pointers() to relocate the heap contents
1799   // accordingly.
1800   const address REQUESTED_BASE = (address)0x10000000;
1801   intx delta = REQUESTED_BASE - actual_base;
1802 
1803   address requested_addr = dumptime_addr + delta;
1804   assert(REQUESTED_BASE != 0 && requested_addr != NULL, "sanity");
1805   return requested_addr;
1806 }
1807 
1808 ResourceBitMap HeapShared::calculate_oopmap(MemRegion region) {
1809   size_t num_bits = region.byte_size() / (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
1810   ResourceBitMap oopmap(num_bits);
1811 
1812   HeapWord* p   = region.start();
1813   HeapWord* end = region.end();
1814   FindEmbeddedNonNullPointers finder((void*)p, &oopmap);
1815   ArchiveBuilder* builder = DumpSharedSpaces ? ArchiveBuilder::current() : NULL;
1816 
1817   int num_objs = 0;
1818   while (p < end) {
1819     oop o = cast_to_oop(p);
1820     o->oop_iterate(&finder);
1821     p += o->size();
1822     if (DumpSharedSpaces) {
1823       builder->relocate_klass_ptr_of_oop(o);
1824     }
1825     ++ num_objs;
1826   }
1827 
1828   log_info(cds, heap)("calculate_oopmap: objects = %6d, oop fields = %7d (nulls = %7d)",
1829                       num_objs, finder.num_total_oops(), finder.num_null_oops());
1830   return oopmap;
1831 }
1832 
1833 
1834 ResourceBitMap HeapShared::calculate_ptrmap(MemRegion region) {
1835   size_t num_bits = region.byte_size() / sizeof(Metadata*);
1836   ResourceBitMap oopmap(num_bits);
1837 
1838   Metadata** start = (Metadata**)region.start();
1839   Metadata** end   = (Metadata**)region.end();
1840 
1841   int num_non_null_ptrs = 0;
1842   int len = _native_pointers->length();
1843   for (int i = 0; i < len; i++) {
1844     Metadata** p = _native_pointers->at(i);
1845     if (start <= p && p < end) {
1846       assert(*p != NULL, "must be non-null");
1847       num_non_null_ptrs ++;
1848       size_t idx = p - start;
1849       oopmap.set_bit(idx);
1850     }
1851   }
1852 
1853   log_info(cds, heap)("calculate_ptrmap: marked %d non-null native pointers out of "
1854                       SIZE_FORMAT " possible locations", num_non_null_ptrs, num_bits);
1855   if (num_non_null_ptrs > 0) {
1856     return oopmap;
1857   } else {
1858     return ResourceBitMap(0);
1859   }
1860 }
1861 
1862 void HeapShared::count_allocation(size_t size) {
1863   _total_obj_count ++;
1864   _total_obj_size += size;
1865   for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
1866     if (size <= (size_t(1) << i)) {
1867       _alloc_count[i] ++;
1868       _alloc_size[i] += size;
1869       return;
1870     }
1871   }
1872 }
1873 
1874 static double avg_size(size_t size, size_t count) {
1875   double avg = 0;
1876   if (count > 0) {
1877     avg = double(size * HeapWordSize) / double(count);
1878   }
1879   return avg;
1880 }
1881 
1882 void HeapShared::print_stats() {
1883   size_t huge_count = _total_obj_count;
1884   size_t huge_size = _total_obj_size;
1885 
1886   for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
1887     size_t byte_size_limit = (size_t(1) << i) * HeapWordSize;
1888     size_t count = _alloc_count[i];
1889     size_t size = _alloc_size[i];
1890     log_info(cds, heap)(SIZE_FORMAT_W(8) " objects are <= " SIZE_FORMAT_W(-6)
1891                         " bytes (total " SIZE_FORMAT_W(8) " bytes, avg %8.1f bytes)",
1892                         count, byte_size_limit, size * HeapWordSize, avg_size(size, count));
1893     huge_count -= count;
1894     huge_size -= size;
1895   }
1896 
1897   log_info(cds, heap)(SIZE_FORMAT_W(8) " huge  objects               (total "  SIZE_FORMAT_W(8) " bytes"
1898                       ", avg %8.1f bytes)",
1899                       huge_count, huge_size * HeapWordSize,
1900                       avg_size(huge_size, huge_count));
1901   log_info(cds, heap)(SIZE_FORMAT_W(8) " total objects               (total "  SIZE_FORMAT_W(8) " bytes"
1902                       ", avg %8.1f bytes)",
1903                       _total_obj_count, _total_obj_size * HeapWordSize,
1904                       avg_size(_total_obj_size, _total_obj_count));
1905 }
1906 
1907 #endif // INCLUDE_CDS_JAVA_HEAP