1 /*
2 * Copyright (c) 2018, 2025, 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 "cds/aotArtifactFinder.hpp"
26 #include "cds/aotClassInitializer.hpp"
27 #include "cds/aotClassLocation.hpp"
28 #include "cds/archiveBuilder.hpp"
29 #include "cds/archiveHeapLoader.hpp"
30 #include "cds/archiveHeapWriter.hpp"
31 #include "cds/archiveUtils.hpp"
32 #include "cds/cdsConfig.hpp"
33 #include "cds/cdsEnumKlass.hpp"
34 #include "cds/cdsHeapVerifier.hpp"
35 #include "cds/heapShared.hpp"
36 #include "cds/metaspaceShared.hpp"
37 #include "classfile/classLoaderData.hpp"
38 #include "classfile/classLoaderExt.hpp"
39 #include "classfile/javaClasses.inline.hpp"
40 #include "classfile/modules.hpp"
41 #include "classfile/stringTable.hpp"
42 #include "classfile/symbolTable.hpp"
43 #include "classfile/systemDictionary.hpp"
44 #include "classfile/systemDictionaryShared.hpp"
45 #include "classfile/vmClasses.hpp"
46 #include "classfile/vmSymbols.hpp"
47 #include "gc/shared/collectedHeap.hpp"
48 #include "gc/shared/gcLocker.hpp"
49 #include "gc/shared/gcVMOperations.hpp"
50 #include "logging/log.hpp"
51 #include "logging/logStream.hpp"
52 #include "memory/iterator.inline.hpp"
53 #include "memory/resourceArea.hpp"
54 #include "memory/universe.hpp"
55 #include "oops/compressedOops.inline.hpp"
56 #include "oops/fieldStreams.inline.hpp"
57 #include "oops/objArrayOop.inline.hpp"
58 #include "oops/oop.inline.hpp"
59 #include "oops/typeArrayOop.inline.hpp"
60 #include "prims/jvmtiExport.hpp"
61 #include "runtime/arguments.hpp"
62 #include "runtime/fieldDescriptor.inline.hpp"
63 #include "runtime/init.hpp"
64 #include "runtime/javaCalls.hpp"
65 #include "runtime/mutexLocker.hpp"
66 #include "runtime/safepointVerifiers.hpp"
67 #include "utilities/bitMap.inline.hpp"
68 #include "utilities/copy.hpp"
69 #if INCLUDE_G1GC
70 #include "gc/g1/g1CollectedHeap.hpp"
71 #endif
72
73 #if INCLUDE_CDS_JAVA_HEAP
74
75 struct ArchivableStaticFieldInfo {
76 const char* klass_name;
77 const char* field_name;
78 InstanceKlass* klass;
79 int offset;
80 BasicType type;
81
82 ArchivableStaticFieldInfo(const char* k, const char* f)
83 : klass_name(k), field_name(f), klass(nullptr), offset(0), type(T_ILLEGAL) {}
84
85 bool valid() {
86 return klass_name != nullptr;
87 }
88 };
89
90 DumpedInternedStrings *HeapShared::_dumped_interned_strings = nullptr;
91
92 size_t HeapShared::_alloc_count[HeapShared::ALLOC_STAT_SLOTS];
93 size_t HeapShared::_alloc_size[HeapShared::ALLOC_STAT_SLOTS];
94 size_t HeapShared::_total_obj_count;
95 size_t HeapShared::_total_obj_size;
96
97 #ifndef PRODUCT
98 #define ARCHIVE_TEST_FIELD_NAME "archivedObjects"
99 static Array<char>* _archived_ArchiveHeapTestClass = nullptr;
100 static const char* _test_class_name = nullptr;
101 static Klass* _test_class = nullptr;
102 static const ArchivedKlassSubGraphInfoRecord* _test_class_record = nullptr;
103 #endif
104
105
106 //
107 // If you add new entries to the following tables, you should know what you're doing!
108 //
109
110 static ArchivableStaticFieldInfo archive_subgraph_entry_fields[] = {
111 {"java/lang/Integer$IntegerCache", "archivedCache"},
112 {"java/lang/Long$LongCache", "archivedCache"},
113 {"java/lang/Byte$ByteCache", "archivedCache"},
114 {"java/lang/Short$ShortCache", "archivedCache"},
115 {"java/lang/Character$CharacterCache", "archivedCache"},
116 {"java/util/jar/Attributes$Name", "KNOWN_NAMES"},
117 {"sun/util/locale/BaseLocale", "constantBaseLocales"},
118 {"jdk/internal/module/ArchivedModuleGraph", "archivedModuleGraph"},
119 {"java/util/ImmutableCollections", "archivedObjects"},
120 {"java/lang/ModuleLayer", "EMPTY_LAYER"},
121 {"java/lang/module/Configuration", "EMPTY_CONFIGURATION"},
122 {"jdk/internal/math/FDBigInteger", "archivedCaches"},
123
124 #ifndef PRODUCT
125 {nullptr, nullptr}, // Extra slot for -XX:ArchiveHeapTestClass
126 #endif
127 {nullptr, nullptr},
128 };
129
130 // full module graph
131 static ArchivableStaticFieldInfo fmg_archive_subgraph_entry_fields[] = {
132 {"jdk/internal/loader/ArchivedClassLoaders", "archivedClassLoaders"},
133 {ARCHIVED_BOOT_LAYER_CLASS, ARCHIVED_BOOT_LAYER_FIELD},
134 {"java/lang/Module$ArchivedData", "archivedData"},
135 {nullptr, nullptr},
136 };
137
138 KlassSubGraphInfo* HeapShared::_dump_time_special_subgraph;
139 ArchivedKlassSubGraphInfoRecord* HeapShared::_run_time_special_subgraph;
140 GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = nullptr;
141 GrowableArrayCHeap<OopHandle, mtClassShared>* HeapShared::_root_segments = nullptr;
142 int HeapShared::_root_segment_max_size_elems;
143 OopHandle HeapShared::_scratch_basic_type_mirrors[T_VOID+1];
144 MetaspaceObjToOopHandleTable* HeapShared::_scratch_objects_table = nullptr;
145
146 static bool is_subgraph_root_class_of(ArchivableStaticFieldInfo fields[], InstanceKlass* ik) {
147 for (int i = 0; fields[i].valid(); 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(archive_subgraph_entry_fields, ik) ||
157 is_subgraph_root_class_of(fmg_archive_subgraph_entry_fields, ik);
158 }
159
160 unsigned HeapShared::oop_hash(oop const& p) {
161 // Do not call p->identity_hash() as that will update the
162 // object header.
163 return primitive_hash(cast_from_oop<intptr_t>(p));
164 }
165
166 static void reset_states(oop obj, TRAPS) {
167 Handle h_obj(THREAD, obj);
168 InstanceKlass* klass = InstanceKlass::cast(obj->klass());
169 TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
170 Symbol* method_sig = vmSymbols::void_method_signature();
171
172 while (klass != nullptr) {
173 Method* method = klass->find_method(method_name, method_sig);
174 if (method != nullptr) {
175 assert(method->is_private(), "must be");
176 if (log_is_enabled(Debug, cds)) {
177 ResourceMark rm(THREAD);
178 log_debug(cds)(" calling %s", method->name_and_sig_as_C_string());
179 }
180 JavaValue result(T_VOID);
181 JavaCalls::call_special(&result, h_obj, klass,
182 method_name, method_sig, CHECK);
183 }
184 klass = klass->java_super();
185 }
186 }
187
188 void HeapShared::reset_archived_object_states(TRAPS) {
189 assert(CDSConfig::is_dumping_heap(), "dump-time only");
190 log_debug(cds)("Resetting platform loader");
191 reset_states(SystemDictionary::java_platform_loader(), CHECK);
192 log_debug(cds)("Resetting system loader");
193 reset_states(SystemDictionary::java_system_loader(), CHECK);
194
195 // Clean up jdk.internal.loader.ClassLoaders::bootLoader(), which is not
196 // directly used for class loading, but rather is used by the core library
197 // to keep track of resources, etc, loaded by the null class loader.
198 //
199 // Note, this object is non-null, and is not the same as
200 // ClassLoaderData::the_null_class_loader_data()->class_loader(),
201 // which is null.
202 log_debug(cds)("Resetting boot loader");
203 JavaValue result(T_OBJECT);
204 JavaCalls::call_static(&result,
205 vmClasses::jdk_internal_loader_ClassLoaders_klass(),
206 vmSymbols::bootLoader_name(),
207 vmSymbols::void_BuiltinClassLoader_signature(),
208 CHECK);
209 Handle boot_loader(THREAD, result.get_oop());
210 reset_states(boot_loader(), CHECK);
211 }
212
213 HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = nullptr;
214
215 bool HeapShared::has_been_archived(oop obj) {
216 assert(CDSConfig::is_dumping_heap(), "dump-time only");
217 return archived_object_cache()->get(obj) != nullptr;
218 }
219
220 int HeapShared::append_root(oop obj) {
221 assert(CDSConfig::is_dumping_heap(), "dump-time only");
222 if (obj != nullptr) {
223 assert(has_been_archived(obj), "must be");
224 }
225 // No GC should happen since we aren't scanning _pending_roots.
226 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
227
228 return _pending_roots->append(obj);
229 }
230
231 objArrayOop HeapShared::root_segment(int segment_idx) {
232 if (CDSConfig::is_dumping_heap()) {
233 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
234 } else {
235 assert(CDSConfig::is_using_archive(), "must be");
236 }
237
238 objArrayOop segment = (objArrayOop)_root_segments->at(segment_idx).resolve();
239 assert(segment != nullptr, "should have been initialized");
240 return segment;
241 }
242
243 void HeapShared::get_segment_indexes(int idx, int& seg_idx, int& int_idx) {
244 assert(_root_segment_max_size_elems > 0, "sanity");
245
246 // Try to avoid divisions for the common case.
247 if (idx < _root_segment_max_size_elems) {
248 seg_idx = 0;
249 int_idx = idx;
250 } else {
251 seg_idx = idx / _root_segment_max_size_elems;
252 int_idx = idx % _root_segment_max_size_elems;
253 }
254
255 assert(idx == seg_idx * _root_segment_max_size_elems + int_idx,
256 "sanity: %d index maps to %d segment and %d internal", idx, seg_idx, int_idx);
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 assert(!CDSConfig::is_dumping_heap() && CDSConfig::is_using_archive(), "runtime only");
263 assert(!_root_segments->is_empty(), "must have loaded shared heap");
264 int seg_idx, int_idx;
265 get_segment_indexes(index, seg_idx, int_idx);
266 oop result = root_segment(seg_idx)->obj_at(int_idx);
267 if (clear) {
268 clear_root(index);
269 }
270 return result;
271 }
272
273 void HeapShared::clear_root(int index) {
274 assert(index >= 0, "sanity");
275 assert(CDSConfig::is_using_archive(), "must be");
276 if (ArchiveHeapLoader::is_in_use()) {
277 int seg_idx, int_idx;
278 get_segment_indexes(index, seg_idx, int_idx);
279 if (log_is_enabled(Debug, cds, heap)) {
280 oop old = root_segment(seg_idx)->obj_at(int_idx);
281 log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
282 }
283 root_segment(seg_idx)->obj_at_put(int_idx, nullptr);
284 }
285 }
286
287 bool HeapShared::archive_object(oop obj, oop referrer, KlassSubGraphInfo* subgraph_info) {
288 assert(CDSConfig::is_dumping_heap(), "dump-time only");
289
290 assert(!obj->is_stackChunk(), "do not archive stack chunks");
291 if (has_been_archived(obj)) {
292 return true;
293 }
294
295 if (ArchiveHeapWriter::is_too_large_to_archive(obj->size())) {
296 log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: %zu",
297 p2i(obj), obj->size());
298 debug_trace();
299 return false;
300 } else {
301 count_allocation(obj->size());
302 ArchiveHeapWriter::add_source_obj(obj);
303 CachedOopInfo info = make_cached_oop_info(obj, referrer);
304 archived_object_cache()->put_when_absent(obj, info);
305 archived_object_cache()->maybe_grow();
306 mark_native_pointers(obj);
307
308 Klass* k = obj->klass();
309 if (k->is_instance_klass()) {
310 // Whenever we see a non-array Java object of type X, we mark X to be aot-initialized.
311 // This ensures that during the production run, whenever Java code sees a cached object
312 // of type X, we know that X is already initialized. (see TODO comment below ...)
313
314 if (InstanceKlass::cast(k)->is_enum_subclass()
315 // We can't rerun <clinit> of enum classes (see cdsEnumKlass.cpp) so
316 // we must store them as AOT-initialized.
317 || (subgraph_info == _dump_time_special_subgraph))
318 // TODO: we do this only for the special subgraph for now. Extending this to
319 // other subgraphs would require more refactoring of the core library (such as
320 // move some initialization logic into runtimeSetup()).
321 //
322 // For the other subgraphs, we have a weaker mechanism to ensure that
323 // all classes in a subgraph are initialized before the subgraph is programmatically
324 // returned from jdk.internal.misc.CDS::initializeFromArchive().
325 // See HeapShared::initialize_from_archived_subgraph().
326 {
327 AOTArtifactFinder::add_aot_inited_class(InstanceKlass::cast(k));
328 }
329
330 if (java_lang_Class::is_instance(obj)) {
331 Klass* mirror_k = java_lang_Class::as_Klass(obj);
332 if (mirror_k != nullptr) {
333 AOTArtifactFinder::add_cached_class(mirror_k);
334 }
335 } else if (java_lang_invoke_ResolvedMethodName::is_instance(obj)) {
336 Method* m = java_lang_invoke_ResolvedMethodName::vmtarget(obj);
337 if (m != nullptr) {
338 InstanceKlass* method_holder = m->method_holder();
339 AOTArtifactFinder::add_cached_class(method_holder);
340 }
341 }
342 }
343
344 if (log_is_enabled(Debug, cds, heap)) {
345 ResourceMark rm;
346 LogTarget(Debug, cds, heap) log;
347 LogStream out(log);
348 out.print("Archived heap object " PTR_FORMAT " : %s ",
349 p2i(obj), obj->klass()->external_name());
350 if (java_lang_Class::is_instance(obj)) {
351 Klass* k = java_lang_Class::as_Klass(obj);
352 if (k != nullptr) {
353 out.print("%s", k->external_name());
354 } else {
355 out.print("primitive");
356 }
357 }
358 out.cr();
359 }
360
361 return true;
362 }
363 }
364
365 class MetaspaceObjToOopHandleTable: public ResourceHashtable<MetaspaceObj*, OopHandle,
366 36137, // prime number
367 AnyObj::C_HEAP,
368 mtClassShared> {
369 public:
370 oop get_oop(MetaspaceObj* ptr) {
371 MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
372 OopHandle* handle = get(ptr);
373 if (handle != nullptr) {
374 return handle->resolve();
375 } else {
376 return nullptr;
377 }
378 }
379 void set_oop(MetaspaceObj* ptr, oop o) {
380 MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
381 OopHandle handle(Universe::vm_global(), o);
382 bool is_new = put(ptr, handle);
383 assert(is_new, "cannot set twice");
384 }
385 void remove_oop(MetaspaceObj* ptr) {
386 MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
387 OopHandle* handle = get(ptr);
388 if (handle != nullptr) {
389 handle->release(Universe::vm_global());
390 remove(ptr);
391 }
392 }
393 };
394
395 void HeapShared::add_scratch_resolved_references(ConstantPool* src, objArrayOop dest) {
396 if (SystemDictionaryShared::is_builtin_loader(src->pool_holder()->class_loader_data())) {
397 _scratch_objects_table->set_oop(src, dest);
398 }
399 }
400
401 objArrayOop HeapShared::scratch_resolved_references(ConstantPool* src) {
402 return (objArrayOop)_scratch_objects_table->get_oop(src);
403 }
404
405 void HeapShared::init_dumping() {
406 _scratch_objects_table = new (mtClass)MetaspaceObjToOopHandleTable();
407 _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
408 }
409
410 void HeapShared::init_scratch_objects_for_basic_type_mirrors(TRAPS) {
411 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
412 BasicType bt = (BasicType)i;
413 if (!is_reference_type(bt)) {
414 oop m = java_lang_Class::create_basic_type_mirror(type2name(bt), bt, true, CHECK);
415 _scratch_basic_type_mirrors[i] = OopHandle(Universe::vm_global(), m);
416 }
417 }
418 }
419
420 // Given java_mirror that represents a (primitive or reference) type T,
421 // return the "scratch" version that represents the same type T.
422 // Note that if java_mirror will be returned if it's already a
423 // scratch mirror.
424 //
425 // See java_lang_Class::create_scratch_mirror() for more info.
426 oop HeapShared::scratch_java_mirror(oop java_mirror) {
427 assert(java_lang_Class::is_instance(java_mirror), "must be");
428
429 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
430 BasicType bt = (BasicType)i;
431 if (!is_reference_type(bt)) {
432 if (_scratch_basic_type_mirrors[i].resolve() == java_mirror) {
433 return java_mirror;
434 }
435 }
436 }
437
438 if (java_lang_Class::is_primitive(java_mirror)) {
439 return scratch_java_mirror(java_lang_Class::as_BasicType(java_mirror));
440 } else {
441 return scratch_java_mirror(java_lang_Class::as_Klass(java_mirror));
442 }
443 }
444
445 oop HeapShared::scratch_java_mirror(BasicType t) {
446 assert((uint)t < T_VOID+1, "range check");
447 assert(!is_reference_type(t), "sanity");
448 return _scratch_basic_type_mirrors[t].resolve();
449 }
450
451 oop HeapShared::scratch_java_mirror(Klass* k) {
452 return _scratch_objects_table->get_oop(k);
453 }
454
455 void HeapShared::set_scratch_java_mirror(Klass* k, oop mirror) {
456 _scratch_objects_table->set_oop(k, mirror);
457 }
458
459 void HeapShared::remove_scratch_objects(Klass* k) {
460 // Klass is being deallocated. Java mirror can still be alive, and it should not
461 // point to dead klass. We need to break the link from mirror to the Klass.
462 // See how InstanceKlass::deallocate_contents does it for normal mirrors.
463 oop mirror = _scratch_objects_table->get_oop(k);
464 if (mirror != nullptr) {
465 java_lang_Class::set_klass(mirror, nullptr);
466 }
467 _scratch_objects_table->remove_oop(k);
468 if (k->is_instance_klass()) {
469 _scratch_objects_table->remove(InstanceKlass::cast(k)->constants());
470 }
471 }
472
473 //TODO: we eventually want a more direct test for these kinds of things.
474 //For example the JVM could record some bit of context from the creation
475 //of the klass, such as who called the hidden class factory. Using
476 //string compares on names is fragile and will break as soon as somebody
477 //changes the names in the JDK code. See discussion in JDK-8342481 for
478 //related ideas about marking AOT-related classes.
479 bool HeapShared::is_lambda_form_klass(InstanceKlass* ik) {
480 return ik->is_hidden() &&
481 (ik->name()->starts_with("java/lang/invoke/LambdaForm$MH+") ||
482 ik->name()->starts_with("java/lang/invoke/LambdaForm$DMH+") ||
483 ik->name()->starts_with("java/lang/invoke/LambdaForm$BMH+") ||
484 ik->name()->starts_with("java/lang/invoke/LambdaForm$VH+"));
485 }
486
487 bool HeapShared::is_lambda_proxy_klass(InstanceKlass* ik) {
488 return ik->is_hidden() && (ik->name()->index_of_at(0, "$$Lambda+", 9) > 0);
489 }
490
491 bool HeapShared::is_string_concat_klass(InstanceKlass* ik) {
492 return ik->is_hidden() && ik->name()->starts_with("java/lang/String$$StringConcat");
493 }
494
495 bool HeapShared::is_archivable_hidden_klass(InstanceKlass* ik) {
496 return CDSConfig::is_dumping_method_handles() &&
497 (is_lambda_form_klass(ik) || is_lambda_proxy_klass(ik) || is_string_concat_klass(ik));
498 }
499
500
501 void HeapShared::copy_and_rescan_aot_inited_mirror(InstanceKlass* ik) {
502 ik->set_has_aot_initialized_mirror();
503 if (AOTClassInitializer::is_runtime_setup_required(ik)) {
504 ik->set_is_runtime_setup_required();
505 }
506
507 oop orig_mirror = ik->java_mirror();
508 oop m = scratch_java_mirror(ik);
509 assert(ik->is_initialized(), "must be");
510
511 int nfields = 0;
512 for (JavaFieldStream fs(ik); !fs.done(); fs.next()) {
513 if (fs.access_flags().is_static()) {
514 fieldDescriptor& fd = fs.field_descriptor();
515 int offset = fd.offset();
516 switch (fd.field_type()) {
517 case T_OBJECT:
518 case T_ARRAY:
519 {
520 oop field_obj = orig_mirror->obj_field(offset);
521 if (offset == java_lang_Class::reflection_data_offset()) {
522 // Class::reflectData use SoftReference, which cannot be archived. Set it
523 // to null and it will be recreated at runtime.
524 field_obj = nullptr;
525 }
526 m->obj_field_put(offset, field_obj);
527 if (field_obj != nullptr) {
528 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, field_obj);
529 assert(success, "sanity");
530 }
531 }
532 break;
533 case T_BOOLEAN:
534 m->bool_field_put(offset, orig_mirror->bool_field(offset));
535 break;
536 case T_BYTE:
537 m->byte_field_put(offset, orig_mirror->byte_field(offset));
538 break;
539 case T_SHORT:
540 m->short_field_put(offset, orig_mirror->short_field(offset));
541 break;
542 case T_CHAR:
543 m->char_field_put(offset, orig_mirror->char_field(offset));
544 break;
545 case T_INT:
546 m->int_field_put(offset, orig_mirror->int_field(offset));
547 break;
548 case T_LONG:
549 m->long_field_put(offset, orig_mirror->long_field(offset));
550 break;
551 case T_FLOAT:
552 m->float_field_put(offset, orig_mirror->float_field(offset));
553 break;
554 case T_DOUBLE:
555 m->double_field_put(offset, orig_mirror->double_field(offset));
556 break;
557 default:
558 ShouldNotReachHere();
559 }
560 nfields ++;
561 }
562 }
563
564 oop class_data = java_lang_Class::class_data(orig_mirror);
565 java_lang_Class::set_class_data(m, class_data);
566 if (class_data != nullptr) {
567 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, class_data);
568 assert(success, "sanity");
569 }
570
571 if (log_is_enabled(Debug, cds, init)) {
572 ResourceMark rm;
573 log_debug(cds, init)("copied %3d field(s) in aot-initialized mirror %s%s%s", nfields, ik->external_name(),
574 ik->is_hidden() ? " (hidden)" : "",
575 ik->is_enum_subclass() ? " (enum)" : "");
576 }
577 }
578
579 static void copy_java_mirror_hashcode(oop orig_mirror, oop scratch_m) {
580 // We need to retain the identity_hash, because it may have been used by some hashtables
581 // in the shared heap.
582 assert(!UseCompactObjectHeaders || scratch_m->mark().is_not_hashed_expanded(), "scratch mirror must have not-hashed-expanded state");
583 if (!orig_mirror->fast_no_hash_check()) {
584 intptr_t orig_mark = orig_mirror->mark().value();
585 intptr_t src_hash = orig_mirror->identity_hash();
586 if (UseCompactObjectHeaders) {
587 // We leave the cases not_hashed/not_hashed_expanded as they are.
588 assert(orig_mirror->mark().is_hashed_not_expanded() || orig_mirror->mark().is_hashed_expanded(), "must be hashed");
589 Klass* orig_klass = orig_mirror->klass();
590 narrowKlass nk = CompressedKlassPointers::encode(orig_klass);
591 markWord mark = markWord::prototype().set_narrow_klass(nk);
592 mark = mark.copy_hashctrl_from(orig_mirror->mark());
593 if (mark.is_hashed_not_expanded()) {
594 scratch_m->initialize_hash_if_necessary(orig_mirror, orig_klass, mark);
595 } else {
596 assert(mark.is_hashed_expanded(), "must be hashed & moved");
597 int offset = orig_klass->hash_offset_in_bytes(orig_mirror, mark);
598 assert(offset >= 8, "hash offset must not be in header");
599 scratch_m->int_field_put(offset, (jint) src_hash);
600 scratch_m->set_mark(mark);
601 }
602 assert(scratch_m->mark().is_hashed_expanded(), "must be hashed & moved");
603 assert(scratch_m->mark().is_not_hashed_expanded() || scratch_m->mark().is_hashed_expanded(), "must be not hashed and expanded");
604 } else {
605 scratch_m->set_mark(markWord::prototype().copy_set_hash(src_hash));
606 DEBUG_ONLY(intptr_t archived_hash = scratch_m->identity_hash());
607 assert(src_hash == archived_hash, "Different hash codes: original " INTPTR_FORMAT ", archived " INTPTR_FORMAT, src_hash, archived_hash);
608 }
609 assert(scratch_m->mark().is_unlocked(), "sanity");
610 }
611 }
612
613 static objArrayOop get_archived_resolved_references(InstanceKlass* src_ik) {
614 if (SystemDictionaryShared::is_builtin_loader(src_ik->class_loader_data())) {
615 objArrayOop rr = src_ik->constants()->resolved_references_or_null();
616 if (rr != nullptr && !ArchiveHeapWriter::is_too_large_to_archive(rr)) {
617 return HeapShared::scratch_resolved_references(src_ik->constants());
618 }
619 }
620 return nullptr;
621 }
622
623 void HeapShared::archive_strings() {
624 oop shared_strings_array = StringTable::init_shared_strings_array(_dumped_interned_strings);
625 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, shared_strings_array);
626 // We must succeed because:
627 // - _dumped_interned_strings do not contain any large strings.
628 // - StringTable::init_shared_table() doesn't create any large arrays.
629 assert(success, "shared strings array must not point to arrays or strings that are too large to archive");
630 StringTable::set_shared_strings_array_index(append_root(shared_strings_array));
631 }
632
633 int HeapShared::archive_exception_instance(oop exception) {
634 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, exception);
635 assert(success, "sanity");
636 return append_root(exception);
637 }
638
639 void HeapShared::mark_native_pointers(oop orig_obj) {
640 if (java_lang_Class::is_instance(orig_obj)) {
641 ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::klass_offset());
642 ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::array_klass_offset());
643 } else if (java_lang_invoke_ResolvedMethodName::is_instance(orig_obj)) {
644 ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_invoke_ResolvedMethodName::vmtarget_offset());
645 }
646 }
647
648 void HeapShared::get_pointer_info(oop src_obj, bool& has_oop_pointers, bool& has_native_pointers) {
649 CachedOopInfo* info = archived_object_cache()->get(src_obj);
650 assert(info != nullptr, "must be");
651 has_oop_pointers = info->has_oop_pointers();
652 has_native_pointers = info->has_native_pointers();
653 }
654
655 void HeapShared::set_has_native_pointers(oop src_obj) {
656 CachedOopInfo* info = archived_object_cache()->get(src_obj);
657 assert(info != nullptr, "must be");
658 info->set_has_native_pointers();
659 }
660
661 // Between start_scanning_for_oops() and end_scanning_for_oops(), we discover all Java heap objects that
662 // should be stored in the AOT cache. The scanning is coordinated by AOTArtifactFinder.
663 void HeapShared::start_scanning_for_oops() {
664 {
665 NoSafepointVerifier nsv;
666
667 // The special subgraph doesn't belong to any class. We use Object_klass() here just
668 // for convenience.
669 _dump_time_special_subgraph = init_subgraph_info(vmClasses::Object_klass(), false);
670
671 // Cache for recording where the archived objects are copied to
672 create_archived_object_cache();
673
674 if (UseCompressedOops || UseG1GC) {
675 log_info(cds)("Heap range = [" PTR_FORMAT " - " PTR_FORMAT "]",
676 UseCompressedOops ? p2i(CompressedOops::begin()) :
677 p2i((address)G1CollectedHeap::heap()->reserved().start()),
678 UseCompressedOops ? p2i(CompressedOops::end()) :
679 p2i((address)G1CollectedHeap::heap()->reserved().end()));
680 }
681
682 archive_subgraphs();
683 }
684
685 init_seen_objects_table();
686 Universe::archive_exception_instances();
687 }
688
689 void HeapShared::end_scanning_for_oops() {
690 archive_strings();
691 delete_seen_objects_table();
692 }
693
694 void HeapShared::write_heap(ArchiveHeapInfo *heap_info) {
695 {
696 NoSafepointVerifier nsv;
697 CDSHeapVerifier::verify();
698 check_special_subgraph_classes();
699 }
700
701 StringTable::write_shared_table(_dumped_interned_strings);
702 ArchiveHeapWriter::write(_pending_roots, heap_info);
703
704 ArchiveBuilder::OtherROAllocMark mark;
705 write_subgraph_info_table();
706 }
707
708 void HeapShared::scan_java_mirror(oop orig_mirror) {
709 oop m = scratch_java_mirror(orig_mirror);
710 if (m != nullptr) { // nullptr if for custom class loader
711 copy_java_mirror_hashcode(orig_mirror, m);
712 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, m);
713 assert(success, "sanity");
714 }
715 }
716
717 void HeapShared::scan_java_class(Klass* orig_k) {
718 scan_java_mirror(orig_k->java_mirror());
719
720 if (orig_k->is_instance_klass()) {
721 InstanceKlass* orig_ik = InstanceKlass::cast(orig_k);
722 orig_ik->constants()->prepare_resolved_references_for_archiving();
723 objArrayOop rr = get_archived_resolved_references(orig_ik);
724 if (rr != nullptr) {
725 bool success = HeapShared::archive_reachable_objects_from(1, _dump_time_special_subgraph, rr);
726 assert(success, "must be");
727 }
728
729 orig_ik->constants()->add_dumped_interned_strings();
730 }
731 }
732
733 void HeapShared::archive_subgraphs() {
734 assert(CDSConfig::is_dumping_heap(), "must be");
735
736 archive_object_subgraphs(archive_subgraph_entry_fields,
737 false /* is_full_module_graph */);
738
739 if (CDSConfig::is_dumping_full_module_graph()) {
740 archive_object_subgraphs(fmg_archive_subgraph_entry_fields,
741 true /* is_full_module_graph */);
742 Modules::verify_archived_modules();
743 }
744 }
745
746 //
747 // Subgraph archiving support
748 //
749 HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = nullptr;
750 HeapShared::RunTimeKlassSubGraphInfoTable HeapShared::_run_time_subgraph_info_table;
751
752 // Get the subgraph_info for Klass k. A new subgraph_info is created if
753 // there is no existing one for k. The subgraph_info records the "buffered"
754 // address of the class.
755 KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
756 assert(CDSConfig::is_dumping_heap(), "dump time only");
757 bool created;
758 KlassSubGraphInfo* info =
759 _dump_time_subgraph_info_table->put_if_absent(k, KlassSubGraphInfo(k, is_full_module_graph),
760 &created);
761 assert(created, "must not initialize twice");
762 return info;
763 }
764
765 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
766 assert(CDSConfig::is_dumping_heap(), "dump time only");
767 KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
768 assert(info != nullptr, "must have been initialized");
769 return info;
770 }
771
772 // Add an entry field to the current KlassSubGraphInfo.
773 void KlassSubGraphInfo::add_subgraph_entry_field(int static_field_offset, oop v) {
774 assert(CDSConfig::is_dumping_heap(), "dump time only");
775 if (_subgraph_entry_fields == nullptr) {
776 _subgraph_entry_fields =
777 new (mtClass) GrowableArray<int>(10, mtClass);
778 }
779 _subgraph_entry_fields->append(static_field_offset);
780 _subgraph_entry_fields->append(HeapShared::append_root(v));
781 }
782
783 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
784 // Only objects of boot classes can be included in sub-graph.
785 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
786 assert(CDSConfig::is_dumping_heap(), "dump time only");
787
788 if (_subgraph_object_klasses == nullptr) {
789 _subgraph_object_klasses =
790 new (mtClass) GrowableArray<Klass*>(50, mtClass);
791 }
792
793 if (_k == orig_k) {
794 // Don't add the Klass containing the sub-graph to it's own klass
795 // initialization list.
796 return;
797 }
798
799 if (orig_k->is_instance_klass()) {
800 #ifdef ASSERT
801 InstanceKlass* ik = InstanceKlass::cast(orig_k);
802 if (CDSConfig::is_dumping_method_handles()) {
803 // -XX:AOTInitTestClass must be used carefully in regression tests to
804 // include only classes that are safe to aot-initialize.
805 assert(ik->class_loader() == nullptr ||
806 HeapShared::is_lambda_proxy_klass(ik) ||
807 AOTClassInitializer::has_test_class(),
808 "we can archive only instances of boot classes or lambda proxy classes");
809 } else {
810 assert(ik->class_loader() == nullptr, "must be boot class");
811 }
812 #endif
813 // vmClasses::xxx_klass() are not updated, need to check
814 // the original Klass*
815 if (orig_k == vmClasses::String_klass() ||
816 orig_k == vmClasses::Object_klass()) {
817 // Initialized early during VM initialization. No need to be added
818 // to the sub-graph object class list.
819 return;
820 }
821 check_allowed_klass(InstanceKlass::cast(orig_k));
822 } else if (orig_k->is_objArray_klass()) {
823 Klass* abk = ObjArrayKlass::cast(orig_k)->bottom_klass();
824 if (abk->is_instance_klass()) {
825 assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
826 "must be boot class");
827 check_allowed_klass(InstanceKlass::cast(ObjArrayKlass::cast(orig_k)->bottom_klass()));
828 }
829 if (orig_k == Universe::objectArrayKlass()) {
830 // Initialized early during Universe::genesis. No need to be added
831 // to the list.
832 return;
833 }
834 } else {
835 assert(orig_k->is_typeArray_klass(), "must be");
836 // Primitive type arrays are created early during Universe::genesis.
837 return;
838 }
839
840 if (log_is_enabled(Debug, cds, heap)) {
841 if (!_subgraph_object_klasses->contains(orig_k)) {
842 ResourceMark rm;
843 log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
844 }
845 }
846
847 _subgraph_object_klasses->append_if_missing(orig_k);
848 _has_non_early_klasses |= is_non_early_klass(orig_k);
849 }
850
851 void KlassSubGraphInfo::check_allowed_klass(InstanceKlass* ik) {
852 #ifndef PRODUCT
853 if (AOTClassInitializer::has_test_class()) {
854 // The tests can cache arbitrary types of objects.
855 return;
856 }
857 #endif
858
859 if (ik->module()->name() == vmSymbols::java_base()) {
860 assert(ik->package() != nullptr, "classes in java.base cannot be in unnamed package");
861 return;
862 }
863
864 const char* lambda_msg = "";
865 if (CDSConfig::is_dumping_method_handles()) {
866 lambda_msg = ", or a lambda proxy class";
867 if (HeapShared::is_lambda_proxy_klass(ik) &&
868 (ik->class_loader() == nullptr ||
869 ik->class_loader() == SystemDictionary::java_platform_loader() ||
870 ik->class_loader() == SystemDictionary::java_system_loader())) {
871 return;
872 }
873 }
874
875 #ifndef PRODUCT
876 if (!ik->module()->is_named() && ik->package() == nullptr && ArchiveHeapTestClass != nullptr) {
877 // This class is loaded by ArchiveHeapTestClass
878 return;
879 }
880 const char* testcls_msg = ", or a test class in an unnamed package of an unnamed module";
881 #else
882 const char* testcls_msg = "";
883 #endif
884
885 ResourceMark rm;
886 log_error(cds, heap)("Class %s not allowed in archive heap. Must be in java.base%s%s",
887 ik->external_name(), lambda_msg, testcls_msg);
888 MetaspaceShared::unrecoverable_writing_error();
889 }
890
891 bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
892 if (k->is_objArray_klass()) {
893 k = ObjArrayKlass::cast(k)->bottom_klass();
894 }
895 if (k->is_instance_klass()) {
896 if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
897 ResourceMark rm;
898 log_info(cds, heap)("non-early: %s", k->external_name());
899 return true;
900 } else {
901 return false;
902 }
903 } else {
904 return false;
905 }
906 }
907
908 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
909 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
910 _k = ArchiveBuilder::get_buffered_klass(info->klass());
911 _entry_field_records = nullptr;
912 _subgraph_object_klasses = nullptr;
913 _is_full_module_graph = info->is_full_module_graph();
914
915 if (_is_full_module_graph) {
916 // Consider all classes referenced by the full module graph as early -- we will be
917 // allocating objects of these classes during JVMTI early phase, so they cannot
918 // be processed by (non-early) JVMTI ClassFileLoadHook
919 _has_non_early_klasses = false;
920 } else {
921 _has_non_early_klasses = info->has_non_early_klasses();
922 }
923
924 if (_has_non_early_klasses) {
925 ResourceMark rm;
926 log_info(cds, heap)(
927 "Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
928 _k->external_name());
929 }
930
931 // populate the entry fields
932 GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
933 if (entry_fields != nullptr) {
934 int num_entry_fields = entry_fields->length();
935 assert(num_entry_fields % 2 == 0, "sanity");
936 _entry_field_records =
937 ArchiveBuilder::new_ro_array<int>(num_entry_fields);
938 for (int i = 0 ; i < num_entry_fields; i++) {
939 _entry_field_records->at_put(i, entry_fields->at(i));
940 }
941 }
942
943 // <recorded_klasses> has the Klasses of all the objects that are referenced by this subgraph.
944 // Copy those that need to be explicitly initialized into <_subgraph_object_klasses>.
945 GrowableArray<Klass*>* recorded_klasses = info->subgraph_object_klasses();
946 if (recorded_klasses != nullptr) {
947 // AOT-inited classes are automatically marked as "initialized" during bootstrap. When
948 // programmatically loading a subgraph, we only need to explicitly initialize the classes
949 // that are not aot-inited.
950 int num_to_copy = 0;
951 for (int i = 0; i < recorded_klasses->length(); i++) {
952 Klass* subgraph_k = ArchiveBuilder::get_buffered_klass(recorded_klasses->at(i));
953 if (!subgraph_k->has_aot_initialized_mirror()) {
954 num_to_copy ++;
955 }
956 }
957
958 _subgraph_object_klasses = ArchiveBuilder::new_ro_array<Klass*>(num_to_copy);
959 bool is_special = (_k == ArchiveBuilder::get_buffered_klass(vmClasses::Object_klass()));
960 for (int i = 0, n = 0; i < recorded_klasses->length(); i++) {
961 Klass* subgraph_k = ArchiveBuilder::get_buffered_klass(recorded_klasses->at(i));
962 if (subgraph_k->has_aot_initialized_mirror()) {
963 continue;
964 }
965 if (log_is_enabled(Info, cds, heap)) {
966 ResourceMark rm;
967 const char* owner_name = is_special ? "<special>" : _k->external_name();
968 if (subgraph_k->is_instance_klass()) {
969 InstanceKlass* src_ik = InstanceKlass::cast(ArchiveBuilder::current()->get_source_addr(subgraph_k));
970 }
971 log_info(cds, heap)(
972 "Archived object klass %s (%2d) => %s",
973 owner_name, n, subgraph_k->external_name());
974 }
975 _subgraph_object_klasses->at_put(n, subgraph_k);
976 ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(n));
977 n++;
978 }
979 }
980
981 ArchivePtrMarker::mark_pointer(&_k);
982 ArchivePtrMarker::mark_pointer(&_entry_field_records);
983 ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
984 }
985
986 class HeapShared::CopyKlassSubGraphInfoToArchive : StackObj {
987 CompactHashtableWriter* _writer;
988 public:
989 CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
990
991 bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
992 if (info.subgraph_object_klasses() != nullptr || info.subgraph_entry_fields() != nullptr) {
993 ArchivedKlassSubGraphInfoRecord* record = HeapShared::archive_subgraph_info(&info);
994 Klass* buffered_k = ArchiveBuilder::get_buffered_klass(klass);
995 unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary((address)buffered_k);
996 u4 delta = ArchiveBuilder::current()->any_to_offset_u4(record);
997 _writer->add(hash, delta);
998 }
999 return true; // keep on iterating
1000 }
1001 };
1002
1003 ArchivedKlassSubGraphInfoRecord* HeapShared::archive_subgraph_info(KlassSubGraphInfo* info) {
1004 ArchivedKlassSubGraphInfoRecord* record =
1005 (ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
1006 record->init(info);
1007 if (info == _dump_time_special_subgraph) {
1008 _run_time_special_subgraph = record;
1009 }
1010 return record;
1011 }
1012
1013 // Build the records of archived subgraph infos, which include:
1014 // - Entry points to all subgraphs from the containing class mirror. The entry
1015 // points are static fields in the mirror. For each entry point, the field
1016 // offset, and value are recorded in the sub-graph
1017 // info. The value is stored back to the corresponding field at runtime.
1018 // - A list of klasses that need to be loaded/initialized before archived
1019 // java object sub-graph can be accessed at runtime.
1020 void HeapShared::write_subgraph_info_table() {
1021 // Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
1022 DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
1023 CompactHashtableStats stats;
1024
1025 _run_time_subgraph_info_table.reset();
1026
1027 CompactHashtableWriter writer(d_table->_count, &stats);
1028 CopyKlassSubGraphInfoToArchive copy(&writer);
1029 d_table->iterate(©);
1030 writer.dump(&_run_time_subgraph_info_table, "subgraphs");
1031
1032 #ifndef PRODUCT
1033 if (ArchiveHeapTestClass != nullptr) {
1034 size_t len = strlen(ArchiveHeapTestClass) + 1;
1035 Array<char>* array = ArchiveBuilder::new_ro_array<char>((int)len);
1036 strncpy(array->adr_at(0), ArchiveHeapTestClass, len);
1037 _archived_ArchiveHeapTestClass = array;
1038 }
1039 #endif
1040 if (log_is_enabled(Info, cds, heap)) {
1041 print_stats();
1042 }
1043 }
1044
1045 void HeapShared::add_root_segment(objArrayOop segment_oop) {
1046 assert(segment_oop != nullptr, "must be");
1047 assert(ArchiveHeapLoader::is_in_use(), "must be");
1048 if (_root_segments == nullptr) {
1049 _root_segments = new GrowableArrayCHeap<OopHandle, mtClassShared>(10);
1050 }
1051 _root_segments->push(OopHandle(Universe::vm_global(), segment_oop));
1052 }
1053
1054 void HeapShared::init_root_segment_sizes(int max_size_elems) {
1055 _root_segment_max_size_elems = max_size_elems;
1056 }
1057
1058 void HeapShared::serialize_tables(SerializeClosure* soc) {
1059
1060 #ifndef PRODUCT
1061 soc->do_ptr(&_archived_ArchiveHeapTestClass);
1062 if (soc->reading() && _archived_ArchiveHeapTestClass != nullptr) {
1063 _test_class_name = _archived_ArchiveHeapTestClass->adr_at(0);
1064 setup_test_class(_test_class_name);
1065 }
1066 #endif
1067
1068 _run_time_subgraph_info_table.serialize_header(soc);
1069 soc->do_ptr(&_run_time_special_subgraph);
1070 }
1071
1072 static void verify_the_heap(Klass* k, const char* which) {
1073 if (VerifyArchivedFields > 0) {
1074 ResourceMark rm;
1075 log_info(cds, heap)("Verify heap %s initializing static field(s) in %s",
1076 which, k->external_name());
1077
1078 VM_Verify verify_op;
1079 VMThread::execute(&verify_op);
1080
1081 if (VerifyArchivedFields > 1 && is_init_completed()) {
1082 // At this time, the oop->klass() of some archived objects in the heap may not
1083 // have been loaded into the system dictionary yet. Nevertheless, oop->klass() should
1084 // have enough information (object size, oop maps, etc) so that a GC can be safely
1085 // performed.
1086 //
1087 // -XX:VerifyArchivedFields=2 force a GC to happen in such an early stage
1088 // to check for GC safety.
1089 log_info(cds, heap)("Trigger GC %s initializing static field(s) in %s",
1090 which, k->external_name());
1091 FlagSetting fs1(VerifyBeforeGC, true);
1092 FlagSetting fs2(VerifyDuringGC, true);
1093 FlagSetting fs3(VerifyAfterGC, true);
1094 Universe::heap()->collect(GCCause::_java_lang_system_gc);
1095 }
1096 }
1097 }
1098
1099 // Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
1100 // have a valid klass. I.e., oopDesc::klass() must have already been resolved.
1101 //
1102 // Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
1103 // ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
1104 // this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
1105 void HeapShared::resolve_classes(JavaThread* current) {
1106 assert(CDSConfig::is_using_archive(), "runtime only!");
1107 if (!ArchiveHeapLoader::is_in_use()) {
1108 return; // nothing to do
1109 }
1110 resolve_classes_for_subgraphs(current, archive_subgraph_entry_fields);
1111 resolve_classes_for_subgraphs(current, fmg_archive_subgraph_entry_fields);
1112 }
1113
1114 void HeapShared::resolve_classes_for_subgraphs(JavaThread* current, ArchivableStaticFieldInfo fields[]) {
1115 for (int i = 0; fields[i].valid(); i++) {
1116 ArchivableStaticFieldInfo* info = &fields[i];
1117 TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
1118 InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
1119 assert(k != nullptr && k->is_shared_boot_class(), "sanity");
1120 resolve_classes_for_subgraph_of(current, k);
1121 }
1122 }
1123
1124 void HeapShared::resolve_classes_for_subgraph_of(JavaThread* current, Klass* k) {
1125 JavaThread* THREAD = current;
1126 ExceptionMark em(THREAD);
1127 const ArchivedKlassSubGraphInfoRecord* record =
1128 resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
1129 if (HAS_PENDING_EXCEPTION) {
1130 CLEAR_PENDING_EXCEPTION;
1131 }
1132 if (record == nullptr) {
1133 clear_archived_roots_of(k);
1134 }
1135 }
1136
1137 void HeapShared::initialize_java_lang_invoke(TRAPS) {
1138 if (CDSConfig::is_using_aot_linked_classes() || CDSConfig::is_dumping_method_handles()) {
1139 resolve_or_init("java/lang/invoke/Invokers$Holder", true, CHECK);
1140 resolve_or_init("java/lang/invoke/MethodHandle", true, CHECK);
1141 resolve_or_init("java/lang/invoke/MethodHandleNatives", true, CHECK);
1142 resolve_or_init("java/lang/invoke/DirectMethodHandle$Holder", true, CHECK);
1143 resolve_or_init("java/lang/invoke/DelegatingMethodHandle$Holder", true, CHECK);
1144 resolve_or_init("java/lang/invoke/LambdaForm$Holder", true, CHECK);
1145 resolve_or_init("java/lang/invoke/BoundMethodHandle$Species_L", true, CHECK);
1146 }
1147 }
1148
1149 // Initialize the InstanceKlasses of objects that are reachable from the following roots:
1150 // - interned strings
1151 // - Klass::java_mirror() -- including aot-initialized mirrors such as those of Enum klasses.
1152 // - ConstantPool::resolved_references()
1153 // - Universe::<xxx>_exception_instance()
1154 //
1155 // For example, if this enum class is initialized at AOT cache assembly time:
1156 //
1157 // enum Fruit {
1158 // APPLE, ORANGE, BANANA;
1159 // static final Set<Fruit> HAVE_SEEDS = new HashSet<>(Arrays.asList(APPLE, ORANGE));
1160 // }
1161 //
1162 // the aot-initialized mirror of Fruit has a static field that references HashSet, which
1163 // should be initialized before any Java code can access the Fruit class. Note that
1164 // HashSet itself doesn't necessary need to be an aot-initialized class.
1165 void HeapShared::init_classes_for_special_subgraph(Handle class_loader, TRAPS) {
1166 if (!ArchiveHeapLoader::is_in_use()) {
1167 return;
1168 }
1169
1170 assert( _run_time_special_subgraph != nullptr, "must be");
1171 Array<Klass*>* klasses = _run_time_special_subgraph->subgraph_object_klasses();
1172 if (klasses != nullptr) {
1173 for (int pass = 0; pass < 2; pass ++) {
1174 for (int i = 0; i < klasses->length(); i++) {
1175 Klass* k = klasses->at(i);
1176 if (k->class_loader_data() == nullptr) {
1177 // This class is not yet loaded. We will initialize it in a later phase.
1178 // For example, we have loaded only AOTLinkedClassCategory::BOOT1 classes
1179 // but k is part of AOTLinkedClassCategory::BOOT2.
1180 continue;
1181 }
1182 if (k->class_loader() == class_loader()) {
1183 if (pass == 0) {
1184 if (k->is_instance_klass()) {
1185 InstanceKlass::cast(k)->link_class(CHECK);
1186 }
1187 } else {
1188 resolve_or_init(k, /*do_init*/true, CHECK);
1189 }
1190 }
1191 }
1192 }
1193 }
1194 }
1195
1196 void HeapShared::initialize_from_archived_subgraph(JavaThread* current, Klass* k) {
1197 JavaThread* THREAD = current;
1198 if (!ArchiveHeapLoader::is_in_use()) {
1199 return; // nothing to do
1200 }
1201
1202 if (k->name()->equals("jdk/internal/module/ArchivedModuleGraph") &&
1203 !CDSConfig::is_using_optimized_module_handling() &&
1204 // archive was created with --module-path
1205 AOTClassLocationConfig::runtime()->num_module_paths() > 0) {
1206 // ArchivedModuleGraph was created with a --module-path that's different than the runtime --module-path.
1207 // Thus, it might contain references to modules that do not exist at runtime. We cannot use it.
1208 log_info(cds, heap)("Skip initializing ArchivedModuleGraph subgraph: is_using_optimized_module_handling=%s num_module_paths=%d",
1209 BOOL_TO_STR(CDSConfig::is_using_optimized_module_handling()),
1210 AOTClassLocationConfig::runtime()->num_module_paths());
1211 return;
1212 }
1213
1214 ExceptionMark em(THREAD);
1215 const ArchivedKlassSubGraphInfoRecord* record =
1216 resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
1217
1218 if (HAS_PENDING_EXCEPTION) {
1219 CLEAR_PENDING_EXCEPTION;
1220 // None of the field value will be set if there was an exception when initializing the classes.
1221 // The java code will not see any of the archived objects in the
1222 // subgraphs referenced from k in this case.
1223 return;
1224 }
1225
1226 if (record != nullptr) {
1227 init_archived_fields_for(k, record);
1228 }
1229 }
1230
1231 const ArchivedKlassSubGraphInfoRecord*
1232 HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
1233 assert(!CDSConfig::is_dumping_heap(), "Should not be called when dumping heap");
1234
1235 if (!k->is_shared()) {
1236 return nullptr;
1237 }
1238 unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
1239 const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
1240
1241 #ifndef PRODUCT
1242 if (_test_class_name != nullptr && k->name()->equals(_test_class_name) && record != nullptr) {
1243 _test_class = k;
1244 _test_class_record = record;
1245 }
1246 #endif
1247
1248 // Initialize from archived data. Currently this is done only
1249 // during VM initialization time. No lock is needed.
1250 if (record == nullptr) {
1251 if (log_is_enabled(Info, cds, heap)) {
1252 ResourceMark rm(THREAD);
1253 log_info(cds, heap)("subgraph %s is not recorded",
1254 k->external_name());
1255 }
1256 return nullptr;
1257 } else {
1258 if (record->is_full_module_graph() && !CDSConfig::is_using_full_module_graph()) {
1259 if (log_is_enabled(Info, cds, heap)) {
1260 ResourceMark rm(THREAD);
1261 log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
1262 k->external_name());
1263 }
1264 return nullptr;
1265 }
1266
1267 if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
1268 if (log_is_enabled(Info, cds, heap)) {
1269 ResourceMark rm(THREAD);
1270 log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
1271 k->external_name());
1272 }
1273 return nullptr;
1274 }
1275
1276 if (log_is_enabled(Info, cds, heap)) {
1277 ResourceMark rm;
1278 log_info(cds, heap)("%s subgraph %s ", do_init ? "init" : "resolve", k->external_name());
1279 }
1280
1281 resolve_or_init(k, do_init, CHECK_NULL);
1282
1283 // Load/link/initialize the klasses of the objects in the subgraph.
1284 // nullptr class loader is used.
1285 Array<Klass*>* klasses = record->subgraph_object_klasses();
1286 if (klasses != nullptr) {
1287 for (int i = 0; i < klasses->length(); i++) {
1288 Klass* klass = klasses->at(i);
1289 if (!klass->is_shared()) {
1290 return nullptr;
1291 }
1292 resolve_or_init(klass, do_init, CHECK_NULL);
1293 }
1294 }
1295 }
1296
1297 return record;
1298 }
1299
1300 void HeapShared::resolve_or_init(const char* klass_name, bool do_init, TRAPS) {
1301 TempNewSymbol klass_name_sym = SymbolTable::new_symbol(klass_name);
1302 InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name_sym);
1303 if (k == nullptr) {
1304 return;
1305 }
1306 assert(k->is_shared_boot_class(), "sanity");
1307 resolve_or_init(k, false, CHECK);
1308 if (do_init) {
1309 resolve_or_init(k, true, CHECK);
1310 }
1311 }
1312
1313 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
1314 if (!do_init) {
1315 if (k->class_loader_data() == nullptr) {
1316 Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
1317 assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
1318 }
1319 } else {
1320 assert(k->class_loader_data() != nullptr, "must have been resolved by HeapShared::resolve_classes");
1321 if (k->is_instance_klass()) {
1322 InstanceKlass* ik = InstanceKlass::cast(k);
1323 ik->initialize(CHECK);
1324 } else if (k->is_objArray_klass()) {
1325 ObjArrayKlass* oak = ObjArrayKlass::cast(k);
1326 oak->initialize(CHECK);
1327 }
1328 }
1329 }
1330
1331 void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record) {
1332 verify_the_heap(k, "before");
1333
1334 // Load the subgraph entry fields from the record and store them back to
1335 // the corresponding fields within the mirror.
1336 oop m = k->java_mirror();
1337 Array<int>* entry_field_records = record->entry_field_records();
1338 if (entry_field_records != nullptr) {
1339 int efr_len = entry_field_records->length();
1340 assert(efr_len % 2 == 0, "sanity");
1341 for (int i = 0; i < efr_len; i += 2) {
1342 int field_offset = entry_field_records->at(i);
1343 int root_index = entry_field_records->at(i+1);
1344 oop v = get_root(root_index, /*clear=*/true);
1345 if (k->has_aot_initialized_mirror()) {
1346 assert(v == m->obj_field(field_offset), "must be aot-initialized");
1347 } else {
1348 m->obj_field_put(field_offset, v);
1349 }
1350 log_debug(cds, heap)(" " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
1351 }
1352
1353 // Done. Java code can see the archived sub-graphs referenced from k's
1354 // mirror after this point.
1355 if (log_is_enabled(Info, cds, heap)) {
1356 ResourceMark rm;
1357 log_info(cds, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s%s",
1358 k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "",
1359 k->has_aot_initialized_mirror() ? " (aot-inited)" : "");
1360 }
1361 }
1362
1363 verify_the_heap(k, "after ");
1364 }
1365
1366 void HeapShared::clear_archived_roots_of(Klass* k) {
1367 unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
1368 const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
1369 if (record != nullptr) {
1370 Array<int>* entry_field_records = record->entry_field_records();
1371 if (entry_field_records != nullptr) {
1372 int efr_len = entry_field_records->length();
1373 assert(efr_len % 2 == 0, "sanity");
1374 for (int i = 0; i < efr_len; i += 2) {
1375 int root_index = entry_field_records->at(i+1);
1376 clear_root(root_index);
1377 }
1378 }
1379 }
1380 }
1381
1382 // Push all oops that are referenced by _referencing_obj onto the _stack.
1383 class HeapShared::ReferentPusher: public BasicOopIterateClosure {
1384 PendingOopStack* _stack;
1385 GrowableArray<oop> _found_oop_fields;
1386 int _level;
1387 bool _record_klasses_only;
1388 KlassSubGraphInfo* _subgraph_info;
1389 oop _referencing_obj;
1390 public:
1391 ReferentPusher(PendingOopStack* stack,
1392 int level,
1393 bool record_klasses_only,
1394 KlassSubGraphInfo* subgraph_info,
1395 oop orig) :
1396 _stack(stack),
1397 _found_oop_fields(),
1398 _level(level),
1399 _record_klasses_only(record_klasses_only),
1400 _subgraph_info(subgraph_info),
1401 _referencing_obj(orig) {
1402 }
1403 void do_oop(narrowOop *p) { ReferentPusher::do_oop_work(p); }
1404 void do_oop( oop *p) { ReferentPusher::do_oop_work(p); }
1405
1406 ~ReferentPusher() {
1407 while (_found_oop_fields.length() > 0) {
1408 // This produces the exact same traversal order as the previous version
1409 // of ReferentPusher that recurses on the C stack -- a depth-first search,
1410 // walking the oop fields in _referencing_obj by ascending field offsets.
1411 oop obj = _found_oop_fields.pop();
1412 _stack->push(PendingOop(obj, _referencing_obj, _level + 1));
1413 }
1414 }
1415
1416 protected:
1417 template <class T> void do_oop_work(T *p) {
1418 oop obj = RawAccess<>::oop_load(p);
1419 if (!CompressedOops::is_null(obj)) {
1420 size_t field_delta = pointer_delta(p, _referencing_obj, sizeof(char));
1421
1422 if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
1423 ResourceMark rm;
1424 log_debug(cds, heap)("(%d) %s[%zu] ==> " PTR_FORMAT " size %zu %s", _level,
1425 _referencing_obj->klass()->external_name(), field_delta,
1426 p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
1427 if (log_is_enabled(Trace, cds, heap)) {
1428 LogTarget(Trace, cds, heap) log;
1429 LogStream out(log);
1430 obj->print_on(&out);
1431 }
1432 }
1433
1434 _found_oop_fields.push(obj);
1435 }
1436 }
1437
1438 public:
1439 oop referencing_obj() { return _referencing_obj; }
1440 KlassSubGraphInfo* subgraph_info() { return _subgraph_info; }
1441 };
1442
1443 // Checks if an oop has any non-null oop fields
1444 class PointsToOopsChecker : public BasicOopIterateClosure {
1445 bool _result;
1446
1447 template <class T> void check(T *p) {
1448 _result |= (HeapAccess<>::oop_load(p) != nullptr);
1449 }
1450
1451 public:
1452 PointsToOopsChecker() : _result(false) {}
1453 void do_oop(narrowOop *p) { check(p); }
1454 void do_oop( oop *p) { check(p); }
1455 bool result() { return _result; }
1456 };
1457
1458 HeapShared::CachedOopInfo HeapShared::make_cached_oop_info(oop obj, oop referrer) {
1459 PointsToOopsChecker points_to_oops_checker;
1460 obj->oop_iterate(&points_to_oops_checker);
1461 return CachedOopInfo(referrer, points_to_oops_checker.result());
1462 }
1463
1464 void HeapShared::init_box_classes(TRAPS) {
1465 if (ArchiveHeapLoader::is_in_use()) {
1466 vmClasses::Boolean_klass()->initialize(CHECK);
1467 vmClasses::Character_klass()->initialize(CHECK);
1468 vmClasses::Float_klass()->initialize(CHECK);
1469 vmClasses::Double_klass()->initialize(CHECK);
1470 vmClasses::Byte_klass()->initialize(CHECK);
1471 vmClasses::Short_klass()->initialize(CHECK);
1472 vmClasses::Integer_klass()->initialize(CHECK);
1473 vmClasses::Long_klass()->initialize(CHECK);
1474 vmClasses::Void_klass()->initialize(CHECK);
1475 }
1476 }
1477
1478 // (1) If orig_obj has not been archived yet, archive it.
1479 // (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
1480 // trace all objects that are reachable from it, and make sure these objects are archived.
1481 // (3) Record the klasses of all objects that are reachable from orig_obj (including those that
1482 // were already archived when this function is called)
1483 bool HeapShared::archive_reachable_objects_from(int level,
1484 KlassSubGraphInfo* subgraph_info,
1485 oop orig_obj) {
1486 assert(orig_obj != nullptr, "must be");
1487 PendingOopStack stack;
1488 stack.push(PendingOop(orig_obj, nullptr, level));
1489
1490 while (stack.length() > 0) {
1491 PendingOop po = stack.pop();
1492 _object_being_archived = po;
1493 bool status = walk_one_object(&stack, po.level(), subgraph_info, po.obj(), po.referrer());
1494 _object_being_archived = PendingOop();
1495
1496 if (!status) {
1497 // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1498 // as the Java code will take care of initializing this field dynamically.
1499 assert(level == 1, "VM should have exited with unarchivable objects for _level > 1");
1500 return false;
1501 }
1502 }
1503
1504 return true;
1505 }
1506
1507 bool HeapShared::walk_one_object(PendingOopStack* stack, int level, KlassSubGraphInfo* subgraph_info,
1508 oop orig_obj, oop referrer) {
1509 assert(orig_obj != nullptr, "must be");
1510 if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
1511 // This object has injected fields that cannot be supported easily, so we disallow them for now.
1512 // If you get an error here, you probably made a change in the JDK library that has added
1513 // these objects that are referenced (directly or indirectly) by static fields.
1514 ResourceMark rm;
1515 log_error(cds, heap)("Cannot archive object " PTR_FORMAT " of class %s", p2i(orig_obj), orig_obj->klass()->external_name());
1516 debug_trace();
1517 MetaspaceShared::unrecoverable_writing_error();
1518 }
1519
1520 if (log_is_enabled(Debug, cds, heap) && java_lang_Class::is_instance(orig_obj)) {
1521 ResourceMark rm;
1522 LogTarget(Debug, cds, heap) log;
1523 LogStream out(log);
1524 out.print("Found java mirror " PTR_FORMAT " ", p2i(orig_obj));
1525 Klass* k = java_lang_Class::as_Klass(orig_obj);
1526 if (k != nullptr) {
1527 out.print("%s", k->external_name());
1528 } else {
1529 out.print("primitive");
1530 }
1531 out.print_cr("; scratch mirror = " PTR_FORMAT,
1532 p2i(scratch_java_mirror(orig_obj)));
1533 }
1534
1535 if (CDSConfig::is_initing_classes_at_dump_time()) {
1536 if (java_lang_Class::is_instance(orig_obj)) {
1537 orig_obj = scratch_java_mirror(orig_obj);
1538 assert(orig_obj != nullptr, "must be archived");
1539 }
1540 } else if (java_lang_Class::is_instance(orig_obj) && subgraph_info != _dump_time_special_subgraph) {
1541 // Without CDSConfig::is_initing_classes_at_dump_time(), we only allow archived objects to
1542 // point to the mirrors of (1) j.l.Object, (2) primitive classes, and (3) box classes. These are initialized
1543 // very early by HeapShared::init_box_classes().
1544 if (orig_obj == vmClasses::Object_klass()->java_mirror()
1545 || java_lang_Class::is_primitive(orig_obj)
1546 || orig_obj == vmClasses::Boolean_klass()->java_mirror()
1547 || orig_obj == vmClasses::Character_klass()->java_mirror()
1548 || orig_obj == vmClasses::Float_klass()->java_mirror()
1549 || orig_obj == vmClasses::Double_klass()->java_mirror()
1550 || orig_obj == vmClasses::Byte_klass()->java_mirror()
1551 || orig_obj == vmClasses::Short_klass()->java_mirror()
1552 || orig_obj == vmClasses::Integer_klass()->java_mirror()
1553 || orig_obj == vmClasses::Long_klass()->java_mirror()
1554 || orig_obj == vmClasses::Void_klass()->java_mirror()) {
1555 orig_obj = scratch_java_mirror(orig_obj);
1556 assert(orig_obj != nullptr, "must be archived");
1557 } else {
1558 // If you get an error here, you probably made a change in the JDK library that has added a Class
1559 // object that is referenced (directly or indirectly) by an ArchivableStaticFieldInfo
1560 // defined at the top of this file.
1561 log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
1562 debug_trace();
1563 MetaspaceShared::unrecoverable_writing_error();
1564 }
1565 }
1566
1567 if (has_been_seen_during_subgraph_recording(orig_obj)) {
1568 // orig_obj has already been archived and traced. Nothing more to do.
1569 return true;
1570 } else {
1571 set_has_been_seen_during_subgraph_recording(orig_obj);
1572 }
1573
1574 bool already_archived = has_been_archived(orig_obj);
1575 bool record_klasses_only = already_archived;
1576 if (!already_archived) {
1577 ++_num_new_archived_objs;
1578 if (!archive_object(orig_obj, referrer, subgraph_info)) {
1579 // Skip archiving the sub-graph referenced from the current entry field.
1580 ResourceMark rm;
1581 log_error(cds, heap)(
1582 "Cannot archive the sub-graph referenced from %s object ("
1583 PTR_FORMAT ") size %zu, skipped.",
1584 orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
1585 if (level == 1) {
1586 // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1587 // as the Java code will take care of initializing this field dynamically.
1588 return false;
1589 } else {
1590 // We don't know how to handle an object that has been archived, but some of its reachable
1591 // objects cannot be archived. Bail out for now. We might need to fix this in the future if
1592 // we have a real use case.
1593 MetaspaceShared::unrecoverable_writing_error();
1594 }
1595 }
1596 }
1597
1598 Klass *orig_k = orig_obj->klass();
1599 subgraph_info->add_subgraph_object_klass(orig_k);
1600
1601 {
1602 // Find all the oops that are referenced by orig_obj, push them onto the stack
1603 // so we can work on them next.
1604 ResourceMark rm;
1605 ReferentPusher pusher(stack, level, record_klasses_only, subgraph_info, orig_obj);
1606 orig_obj->oop_iterate(&pusher);
1607 }
1608
1609 if (CDSConfig::is_initing_classes_at_dump_time()) {
1610 // The enum klasses are archived with aot-initialized mirror.
1611 // See AOTClassInitializer::can_archive_initialized_mirror().
1612 } else {
1613 if (CDSEnumKlass::is_enum_obj(orig_obj)) {
1614 CDSEnumKlass::handle_enum_obj(level + 1, subgraph_info, orig_obj);
1615 }
1616 }
1617
1618 return true;
1619 }
1620
1621 //
1622 // Start from the given static field in a java mirror and archive the
1623 // complete sub-graph of java heap objects that are reached directly
1624 // or indirectly from the starting object by following references.
1625 // Sub-graph archiving restrictions (current):
1626 //
1627 // - All classes of objects in the archived sub-graph (including the
1628 // entry class) must be boot class only.
1629 // - No java.lang.Class instance (java mirror) can be included inside
1630 // an archived sub-graph. Mirror can only be the sub-graph entry object.
1631 //
1632 // The Java heap object sub-graph archiving process (see ReferentPusher):
1633 //
1634 // 1) Java object sub-graph archiving starts from a given static field
1635 // within a Class instance (java mirror). If the static field is a
1636 // reference field and points to a non-null java object, proceed to
1637 // the next step.
1638 //
1639 // 2) Archives the referenced java object. If an archived copy of the
1640 // current object already exists, updates the pointer in the archived
1641 // copy of the referencing object to point to the current archived object.
1642 // Otherwise, proceed to the next step.
1643 //
1644 // 3) Follows all references within the current java object and recursively
1645 // archive the sub-graph of objects starting from each reference.
1646 //
1647 // 4) Updates the pointer in the archived copy of referencing object to
1648 // point to the current archived object.
1649 //
1650 // 5) The Klass of the current java object is added to the list of Klasses
1651 // for loading and initializing before any object in the archived graph can
1652 // be accessed at runtime.
1653 //
1654 void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
1655 const char* klass_name,
1656 int field_offset,
1657 const char* field_name) {
1658 assert(CDSConfig::is_dumping_heap(), "dump time only");
1659 assert(k->is_shared_boot_class(), "must be boot class");
1660
1661 oop m = k->java_mirror();
1662
1663 KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
1664 oop f = m->obj_field(field_offset);
1665
1666 log_debug(cds, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
1667
1668 if (!CompressedOops::is_null(f)) {
1669 if (log_is_enabled(Trace, cds, heap)) {
1670 LogTarget(Trace, cds, heap) log;
1671 LogStream out(log);
1672 f->print_on(&out);
1673 }
1674
1675 bool success = archive_reachable_objects_from(1, subgraph_info, f);
1676 if (!success) {
1677 log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
1678 klass_name, field_name);
1679 } else {
1680 // Note: the field value is not preserved in the archived mirror.
1681 // Record the field as a new subGraph entry point. The recorded
1682 // information is restored from the archive at runtime.
1683 subgraph_info->add_subgraph_entry_field(field_offset, f);
1684 log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(f));
1685 }
1686 } else {
1687 // The field contains null, we still need to record the entry point,
1688 // so it can be restored at runtime.
1689 subgraph_info->add_subgraph_entry_field(field_offset, nullptr);
1690 }
1691 }
1692
1693 #ifndef PRODUCT
1694 class VerifySharedOopClosure: public BasicOopIterateClosure {
1695 public:
1696 void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
1697 void do_oop( oop *p) { VerifySharedOopClosure::do_oop_work(p); }
1698
1699 protected:
1700 template <class T> void do_oop_work(T *p) {
1701 oop obj = RawAccess<>::oop_load(p);
1702 if (!CompressedOops::is_null(obj)) {
1703 HeapShared::verify_reachable_objects_from(obj);
1704 }
1705 }
1706 };
1707
1708 void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
1709 assert(CDSConfig::is_dumping_heap(), "dump time only");
1710 assert(k->is_shared_boot_class(), "must be boot class");
1711
1712 oop m = k->java_mirror();
1713 oop f = m->obj_field(field_offset);
1714 if (!CompressedOops::is_null(f)) {
1715 verify_subgraph_from(f);
1716 }
1717 }
1718
1719 void HeapShared::verify_subgraph_from(oop orig_obj) {
1720 if (!has_been_archived(orig_obj)) {
1721 // It's OK for the root of a subgraph to be not archived. See comments in
1722 // archive_reachable_objects_from().
1723 return;
1724 }
1725
1726 // Verify that all objects reachable from orig_obj are archived.
1727 init_seen_objects_table();
1728 verify_reachable_objects_from(orig_obj);
1729 delete_seen_objects_table();
1730 }
1731
1732 void HeapShared::verify_reachable_objects_from(oop obj) {
1733 _num_total_verifications ++;
1734 if (java_lang_Class::is_instance(obj)) {
1735 obj = scratch_java_mirror(obj);
1736 assert(obj != nullptr, "must be");
1737 }
1738 if (!has_been_seen_during_subgraph_recording(obj)) {
1739 set_has_been_seen_during_subgraph_recording(obj);
1740 assert(has_been_archived(obj), "must be");
1741 VerifySharedOopClosure walker;
1742 obj->oop_iterate(&walker);
1743 }
1744 }
1745 #endif
1746
1747 void HeapShared::check_special_subgraph_classes() {
1748 if (CDSConfig::is_initing_classes_at_dump_time()) {
1749 // We can have aot-initialized classes (such as Enums) that can reference objects
1750 // of arbitrary types. Currently, we trust the JEP 483 implementation to only
1751 // aot-initialize classes that are "safe".
1752 //
1753 // TODO: we need an automatic tool that checks the safety of aot-initialized
1754 // classes (when we extend the set of aot-initialized classes beyond JEP 483)
1755 return;
1756 } else {
1757 // In this case, the special subgraph should contain a few specific types
1758 GrowableArray<Klass*>* klasses = _dump_time_special_subgraph->subgraph_object_klasses();
1759 int num = klasses->length();
1760 for (int i = 0; i < num; i++) {
1761 Klass* subgraph_k = klasses->at(i);
1762 Symbol* name = subgraph_k->name();
1763 if (subgraph_k->is_instance_klass() &&
1764 name != vmSymbols::java_lang_Class() &&
1765 name != vmSymbols::java_lang_String() &&
1766 name != vmSymbols::java_lang_ArithmeticException() &&
1767 name != vmSymbols::java_lang_ArrayIndexOutOfBoundsException() &&
1768 name != vmSymbols::java_lang_ArrayStoreException() &&
1769 name != vmSymbols::java_lang_ClassCastException() &&
1770 name != vmSymbols::java_lang_InternalError() &&
1771 name != vmSymbols::java_lang_NullPointerException()) {
1772 ResourceMark rm;
1773 fatal("special subgraph cannot have objects of type %s", subgraph_k->external_name());
1774 }
1775 }
1776 }
1777 }
1778
1779 HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = nullptr;
1780 HeapShared::PendingOop HeapShared::_object_being_archived;
1781 int HeapShared::_num_new_walked_objs;
1782 int HeapShared::_num_new_archived_objs;
1783 int HeapShared::_num_old_recorded_klasses;
1784
1785 int HeapShared::_num_total_subgraph_recordings = 0;
1786 int HeapShared::_num_total_walked_objs = 0;
1787 int HeapShared::_num_total_archived_objs = 0;
1788 int HeapShared::_num_total_recorded_klasses = 0;
1789 int HeapShared::_num_total_verifications = 0;
1790
1791 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
1792 return _seen_objects_table->get(obj) != nullptr;
1793 }
1794
1795 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
1796 assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
1797 _seen_objects_table->put_when_absent(obj, true);
1798 _seen_objects_table->maybe_grow();
1799 ++ _num_new_walked_objs;
1800 }
1801
1802 void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
1803 log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
1804 init_subgraph_info(k, is_full_module_graph);
1805 init_seen_objects_table();
1806 _num_new_walked_objs = 0;
1807 _num_new_archived_objs = 0;
1808 _num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
1809 }
1810
1811 void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
1812 int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
1813 _num_old_recorded_klasses;
1814 log_info(cds, heap)("Done recording subgraph(s) for archived fields in %s: "
1815 "walked %d objs, archived %d new objs, recorded %d classes",
1816 class_name, _num_new_walked_objs, _num_new_archived_objs,
1817 num_new_recorded_klasses);
1818
1819 delete_seen_objects_table();
1820
1821 _num_total_subgraph_recordings ++;
1822 _num_total_walked_objs += _num_new_walked_objs;
1823 _num_total_archived_objs += _num_new_archived_objs;
1824 _num_total_recorded_klasses += num_new_recorded_klasses;
1825 }
1826
1827 class ArchivableStaticFieldFinder: public FieldClosure {
1828 InstanceKlass* _ik;
1829 Symbol* _field_name;
1830 bool _found;
1831 int _offset;
1832 public:
1833 ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
1834 _ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
1835
1836 virtual void do_field(fieldDescriptor* fd) {
1837 if (fd->name() == _field_name) {
1838 assert(!_found, "fields can never be overloaded");
1839 if (is_reference_type(fd->field_type())) {
1840 _found = true;
1841 _offset = fd->offset();
1842 }
1843 }
1844 }
1845 bool found() { return _found; }
1846 int offset() { return _offset; }
1847 };
1848
1849 void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
1850 TRAPS) {
1851 for (int i = 0; fields[i].valid(); i++) {
1852 ArchivableStaticFieldInfo* info = &fields[i];
1853 TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
1854 TempNewSymbol field_name = SymbolTable::new_symbol(info->field_name);
1855 ResourceMark rm; // for stringStream::as_string() etc.
1856
1857 #ifndef PRODUCT
1858 bool is_test_class = (ArchiveHeapTestClass != nullptr) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
1859 const char* test_class_name = ArchiveHeapTestClass;
1860 #else
1861 bool is_test_class = false;
1862 const char* test_class_name = ""; // avoid C++ printf checks warnings.
1863 #endif
1864
1865 if (is_test_class) {
1866 log_warning(cds)("Loading ArchiveHeapTestClass %s ...", test_class_name);
1867 }
1868
1869 Klass* k = SystemDictionary::resolve_or_fail(klass_name, true, THREAD);
1870 if (HAS_PENDING_EXCEPTION) {
1871 CLEAR_PENDING_EXCEPTION;
1872 stringStream st;
1873 st.print("Fail to initialize archive heap: %s cannot be loaded by the boot loader", info->klass_name);
1874 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1875 }
1876
1877 if (!k->is_instance_klass()) {
1878 stringStream st;
1879 st.print("Fail to initialize archive heap: %s is not an instance class", info->klass_name);
1880 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1881 }
1882
1883 InstanceKlass* ik = InstanceKlass::cast(k);
1884 assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
1885 "Only support boot classes");
1886
1887 if (is_test_class) {
1888 if (ik->module()->is_named()) {
1889 // We don't want ArchiveHeapTestClass to be abused to easily load/initialize arbitrary
1890 // core-lib classes. You need to at least append to the bootclasspath.
1891 stringStream st;
1892 st.print("ArchiveHeapTestClass %s is not in unnamed module", test_class_name);
1893 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1894 }
1895
1896 if (ik->package() != nullptr) {
1897 // This restriction makes HeapShared::is_a_test_class_in_unnamed_module() easy.
1898 stringStream st;
1899 st.print("ArchiveHeapTestClass %s is not in unnamed package", test_class_name);
1900 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1901 }
1902 } else {
1903 if (ik->module()->name() != vmSymbols::java_base()) {
1904 // We don't want to deal with cases when a module is unavailable at runtime.
1905 // FUTURE -- load from archived heap only when module graph has not changed
1906 // between dump and runtime.
1907 stringStream st;
1908 st.print("%s is not in java.base module", info->klass_name);
1909 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1910 }
1911 }
1912
1913 if (is_test_class) {
1914 log_warning(cds)("Initializing ArchiveHeapTestClass %s ...", test_class_name);
1915 }
1916 ik->initialize(CHECK);
1917
1918 ArchivableStaticFieldFinder finder(ik, field_name);
1919 ik->do_local_static_fields(&finder);
1920 if (!finder.found()) {
1921 stringStream st;
1922 st.print("Unable to find the static T_OBJECT field %s::%s", info->klass_name, info->field_name);
1923 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1924 }
1925
1926 info->klass = ik;
1927 info->offset = finder.offset();
1928 }
1929 }
1930
1931 void HeapShared::init_subgraph_entry_fields(TRAPS) {
1932 assert(CDSConfig::is_dumping_heap(), "must be");
1933 _dump_time_subgraph_info_table = new (mtClass)DumpTimeKlassSubGraphInfoTable();
1934 init_subgraph_entry_fields(archive_subgraph_entry_fields, CHECK);
1935 if (CDSConfig::is_dumping_full_module_graph()) {
1936 init_subgraph_entry_fields(fmg_archive_subgraph_entry_fields, CHECK);
1937 }
1938 }
1939
1940 #ifndef PRODUCT
1941 void HeapShared::setup_test_class(const char* test_class_name) {
1942 ArchivableStaticFieldInfo* p = archive_subgraph_entry_fields;
1943 int num_slots = sizeof(archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
1944 assert(p[num_slots - 2].klass_name == nullptr, "must have empty slot that's patched below");
1945 assert(p[num_slots - 1].klass_name == nullptr, "must have empty slot that marks the end of the list");
1946
1947 if (test_class_name != nullptr) {
1948 p[num_slots - 2].klass_name = test_class_name;
1949 p[num_slots - 2].field_name = ARCHIVE_TEST_FIELD_NAME;
1950 }
1951 }
1952
1953 // See if ik is one of the test classes that are pulled in by -XX:ArchiveHeapTestClass
1954 // during runtime. This may be called before the module system is initialized so
1955 // we cannot rely on InstanceKlass::module(), etc.
1956 bool HeapShared::is_a_test_class_in_unnamed_module(Klass* ik) {
1957 if (_test_class != nullptr) {
1958 if (ik == _test_class) {
1959 return true;
1960 }
1961 Array<Klass*>* klasses = _test_class_record->subgraph_object_klasses();
1962 if (klasses == nullptr) {
1963 return false;
1964 }
1965
1966 for (int i = 0; i < klasses->length(); i++) {
1967 Klass* k = klasses->at(i);
1968 if (k == ik) {
1969 Symbol* name;
1970 if (k->is_instance_klass()) {
1971 name = InstanceKlass::cast(k)->name();
1972 } else if (k->is_objArray_klass()) {
1973 Klass* bk = ObjArrayKlass::cast(k)->bottom_klass();
1974 if (!bk->is_instance_klass()) {
1975 return false;
1976 }
1977 name = bk->name();
1978 } else {
1979 return false;
1980 }
1981
1982 // See KlassSubGraphInfo::check_allowed_klass() - we only allow test classes
1983 // to be:
1984 // (A) java.base classes (which must not be in the unnamed module)
1985 // (B) test classes which must be in the unnamed package of the unnamed module.
1986 // So if we see a '/' character in the class name, it must be in (A);
1987 // otherwise it must be in (B).
1988 if (name->index_of_at(0, "/", 1) >= 0) {
1989 return false; // (A)
1990 }
1991
1992 return true; // (B)
1993 }
1994 }
1995 }
1996
1997 return false;
1998 }
1999
2000 void HeapShared::initialize_test_class_from_archive(JavaThread* current) {
2001 Klass* k = _test_class;
2002 if (k != nullptr && ArchiveHeapLoader::is_in_use()) {
2003 JavaThread* THREAD = current;
2004 ExceptionMark em(THREAD);
2005 const ArchivedKlassSubGraphInfoRecord* record =
2006 resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
2007
2008 // The _test_class is in the unnamed module, so it can't call CDS.initializeFromArchive()
2009 // from its <clinit> method. So we set up its "archivedObjects" field first, before
2010 // calling its <clinit>. This is not strictly clean, but it's a convenient way to write unit
2011 // test cases (see test/hotspot/jtreg/runtime/cds/appcds/cacheObject/ArchiveHeapTestClass.java).
2012 if (record != nullptr) {
2013 init_archived_fields_for(k, record);
2014 }
2015 resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
2016 }
2017 }
2018 #endif
2019
2020 void HeapShared::init_for_dumping(TRAPS) {
2021 if (CDSConfig::is_dumping_heap()) {
2022 setup_test_class(ArchiveHeapTestClass);
2023 _dumped_interned_strings = new (mtClass)DumpedInternedStrings(INITIAL_TABLE_SIZE, MAX_TABLE_SIZE);
2024 init_subgraph_entry_fields(CHECK);
2025 }
2026 }
2027
2028 void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
2029 bool is_full_module_graph) {
2030 _num_total_subgraph_recordings = 0;
2031 _num_total_walked_objs = 0;
2032 _num_total_archived_objs = 0;
2033 _num_total_recorded_klasses = 0;
2034 _num_total_verifications = 0;
2035
2036 // For each class X that has one or more archived fields:
2037 // [1] Dump the subgraph of each archived field
2038 // [2] Create a list of all the class of the objects that can be reached
2039 // by any of these static fields.
2040 // At runtime, these classes are initialized before X's archived fields
2041 // are restored by HeapShared::initialize_from_archived_subgraph().
2042 for (int i = 0; fields[i].valid(); ) {
2043 ArchivableStaticFieldInfo* info = &fields[i];
2044 const char* klass_name = info->klass_name;
2045 start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
2046
2047 // If you have specified consecutive fields of the same klass in
2048 // fields[], these will be archived in the same
2049 // {start_recording_subgraph ... done_recording_subgraph} pass to
2050 // save time.
2051 for (; fields[i].valid(); i++) {
2052 ArchivableStaticFieldInfo* f = &fields[i];
2053 if (f->klass_name != klass_name) {
2054 break;
2055 }
2056
2057 archive_reachable_objects_from_static_field(f->klass, f->klass_name,
2058 f->offset, f->field_name);
2059 }
2060 done_recording_subgraph(info->klass, klass_name);
2061 }
2062
2063 log_info(cds, heap)("Archived subgraph records = %d",
2064 _num_total_subgraph_recordings);
2065 log_info(cds, heap)(" Walked %d objects", _num_total_walked_objs);
2066 log_info(cds, heap)(" Archived %d objects", _num_total_archived_objs);
2067 log_info(cds, heap)(" Recorded %d klasses", _num_total_recorded_klasses);
2068
2069 #ifndef PRODUCT
2070 for (int i = 0; fields[i].valid(); i++) {
2071 ArchivableStaticFieldInfo* f = &fields[i];
2072 verify_subgraph_from_static_field(f->klass, f->offset);
2073 }
2074 log_info(cds, heap)(" Verified %d references", _num_total_verifications);
2075 #endif
2076 }
2077
2078 // Not all the strings in the global StringTable are dumped into the archive, because
2079 // some of those strings may be only referenced by classes that are excluded from
2080 // the archive. We need to explicitly mark the strings that are:
2081 // [1] used by classes that WILL be archived;
2082 // [2] included in the SharedArchiveConfigFile.
2083 void HeapShared::add_to_dumped_interned_strings(oop string) {
2084 assert_at_safepoint(); // DumpedInternedStrings uses raw oops
2085 assert(!ArchiveHeapWriter::is_string_too_large_to_archive(string), "must be");
2086 bool created;
2087 _dumped_interned_strings->put_if_absent(string, true, &created);
2088 if (created) {
2089 // Prevent string deduplication from changing the value field to
2090 // something not in the archive.
2091 java_lang_String::set_deduplication_forbidden(string);
2092 _dumped_interned_strings->maybe_grow();
2093 }
2094 }
2095
2096 bool HeapShared::is_dumped_interned_string(oop o) {
2097 return _dumped_interned_strings->get(o) != nullptr;
2098 }
2099
2100 void HeapShared::debug_trace() {
2101 ResourceMark rm;
2102 oop referrer = _object_being_archived.referrer();
2103 if (referrer != nullptr) {
2104 LogStream ls(Log(cds, heap)::error());
2105 ls.print_cr("Reference trace");
2106 CDSHeapVerifier::trace_to_root(&ls, referrer);
2107 }
2108 }
2109
2110 #ifndef PRODUCT
2111 // At dump-time, find the location of all the non-null oop pointers in an archived heap
2112 // region. This way we can quickly relocate all the pointers without using
2113 // BasicOopIterateClosure at runtime.
2114 class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
2115 void* _start;
2116 BitMap *_oopmap;
2117 int _num_total_oops;
2118 int _num_null_oops;
2119 public:
2120 FindEmbeddedNonNullPointers(void* start, BitMap* oopmap)
2121 : _start(start), _oopmap(oopmap), _num_total_oops(0), _num_null_oops(0) {}
2122
2123 virtual void do_oop(narrowOop* p) {
2124 assert(UseCompressedOops, "sanity");
2125 _num_total_oops ++;
2126 narrowOop v = *p;
2127 if (!CompressedOops::is_null(v)) {
2128 size_t idx = p - (narrowOop*)_start;
2129 _oopmap->set_bit(idx);
2130 } else {
2131 _num_null_oops ++;
2132 }
2133 }
2134 virtual void do_oop(oop* p) {
2135 assert(!UseCompressedOops, "sanity");
2136 _num_total_oops ++;
2137 if ((*p) != nullptr) {
2138 size_t idx = p - (oop*)_start;
2139 _oopmap->set_bit(idx);
2140 } else {
2141 _num_null_oops ++;
2142 }
2143 }
2144 int num_total_oops() const { return _num_total_oops; }
2145 int num_null_oops() const { return _num_null_oops; }
2146 };
2147 #endif
2148
2149 void HeapShared::count_allocation(size_t size) {
2150 _total_obj_count ++;
2151 _total_obj_size += size;
2152 for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
2153 if (size <= (size_t(1) << i)) {
2154 _alloc_count[i] ++;
2155 _alloc_size[i] += size;
2156 return;
2157 }
2158 }
2159 }
2160
2161 static double avg_size(size_t size, size_t count) {
2162 double avg = 0;
2163 if (count > 0) {
2164 avg = double(size * HeapWordSize) / double(count);
2165 }
2166 return avg;
2167 }
2168
2169 void HeapShared::print_stats() {
2170 size_t huge_count = _total_obj_count;
2171 size_t huge_size = _total_obj_size;
2172
2173 for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
2174 size_t byte_size_limit = (size_t(1) << i) * HeapWordSize;
2175 size_t count = _alloc_count[i];
2176 size_t size = _alloc_size[i];
2177 log_info(cds, heap)("%8zu objects are <= %-6zu"
2178 " bytes (total %8zu bytes, avg %8.1f bytes)",
2179 count, byte_size_limit, size * HeapWordSize, avg_size(size, count));
2180 huge_count -= count;
2181 huge_size -= size;
2182 }
2183
2184 log_info(cds, heap)("%8zu huge objects (total %8zu bytes"
2185 ", avg %8.1f bytes)",
2186 huge_count, huge_size * HeapWordSize,
2187 avg_size(huge_size, huge_count));
2188 log_info(cds, heap)("%8zu total objects (total %8zu bytes"
2189 ", avg %8.1f bytes)",
2190 _total_obj_count, _total_obj_size * HeapWordSize,
2191 avg_size(_total_obj_size, _total_obj_count));
2192 }
2193
2194 bool HeapShared::is_archived_boot_layer_available(JavaThread* current) {
2195 TempNewSymbol klass_name = SymbolTable::new_symbol(ARCHIVED_BOOT_LAYER_CLASS);
2196 InstanceKlass* k = SystemDictionary::find_instance_klass(current, klass_name, Handle());
2197 if (k == nullptr) {
2198 return false;
2199 } else {
2200 TempNewSymbol field_name = SymbolTable::new_symbol(ARCHIVED_BOOT_LAYER_FIELD);
2201 TempNewSymbol field_signature = SymbolTable::new_symbol("Ljdk/internal/module/ArchivedBootLayer;");
2202 fieldDescriptor fd;
2203 if (k->find_field(field_name, field_signature, true, &fd) != nullptr) {
2204 oop m = k->java_mirror();
2205 oop f = m->obj_field(fd.offset());
2206 if (CompressedOops::is_null(f)) {
2207 return false;
2208 }
2209 } else {
2210 return false;
2211 }
2212 }
2213 return true;
2214 }
2215
2216 #endif // INCLUDE_CDS_JAVA_HEAP