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/aotReferenceObjSupport.hpp"
29 #include "cds/archiveBuilder.hpp"
30 #include "cds/archiveHeapLoader.hpp"
31 #include "cds/archiveHeapWriter.hpp"
32 #include "cds/archiveUtils.hpp"
33 #include "cds/cdsConfig.hpp"
34 #include "cds/cdsEnumKlass.hpp"
35 #include "cds/cdsHeapVerifier.hpp"
36 #include "cds/heapShared.hpp"
37 #include "cds/metaspaceShared.hpp"
38 #include "classfile/classLoaderData.hpp"
39 #include "classfile/classLoaderExt.hpp"
40 #include "classfile/javaClasses.inline.hpp"
41 #include "classfile/modules.hpp"
42 #include "classfile/stringTable.hpp"
43 #include "classfile/symbolTable.hpp"
44 #include "classfile/systemDictionary.hpp"
45 #include "classfile/systemDictionaryShared.hpp"
46 #include "classfile/vmClasses.hpp"
47 #include "classfile/vmSymbols.hpp"
48 #include "gc/shared/collectedHeap.hpp"
49 #include "gc/shared/gcLocker.hpp"
50 #include "gc/shared/gcVMOperations.hpp"
51 #include "logging/log.hpp"
52 #include "logging/logStream.hpp"
53 #include "memory/iterator.inline.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "memory/universe.hpp"
56 #include "oops/compressedOops.inline.hpp"
57 #include "oops/fieldStreams.inline.hpp"
58 #include "oops/objArrayOop.inline.hpp"
59 #include "oops/oop.inline.hpp"
60 #include "oops/typeArrayOop.inline.hpp"
61 #include "prims/jvmtiExport.hpp"
62 #include "runtime/arguments.hpp"
63 #include "runtime/fieldDescriptor.inline.hpp"
64 #include "runtime/init.hpp"
65 #include "runtime/javaCalls.hpp"
66 #include "runtime/mutexLocker.hpp"
67 #include "runtime/safepointVerifiers.hpp"
68 #include "utilities/bitMap.inline.hpp"
69 #include "utilities/copy.hpp"
70 #if INCLUDE_G1GC
71 #include "gc/g1/g1CollectedHeap.hpp"
72 #endif
73
74 #if INCLUDE_CDS_JAVA_HEAP
75
76 struct ArchivableStaticFieldInfo {
77 const char* klass_name;
78 const char* field_name;
79 InstanceKlass* klass;
80 int offset;
81 BasicType type;
82
83 ArchivableStaticFieldInfo(const char* k, const char* f)
84 : klass_name(k), field_name(f), klass(nullptr), offset(0), type(T_ILLEGAL) {}
85
86 bool valid() {
87 return klass_name != nullptr;
88 }
89 };
90
91 DumpedInternedStrings *HeapShared::_dumped_interned_strings = nullptr;
92
93 size_t HeapShared::_alloc_count[HeapShared::ALLOC_STAT_SLOTS];
94 size_t HeapShared::_alloc_size[HeapShared::ALLOC_STAT_SLOTS];
95 size_t HeapShared::_total_obj_count;
96 size_t HeapShared::_total_obj_size;
97
98 #ifndef PRODUCT
99 #define ARCHIVE_TEST_FIELD_NAME "archivedObjects"
100 static Array<char>* _archived_ArchiveHeapTestClass = nullptr;
101 static const char* _test_class_name = nullptr;
102 static Klass* _test_class = nullptr;
103 static const ArchivedKlassSubGraphInfoRecord* _test_class_record = nullptr;
104 #endif
105
106
107 //
108 // If you add new entries to the following tables, you should know what you're doing!
109 //
110
111 static ArchivableStaticFieldInfo archive_subgraph_entry_fields[] = {
112 {"java/lang/Integer$IntegerCache", "archivedCache"},
113 {"java/lang/Long$LongCache", "archivedCache"},
114 {"java/lang/Byte$ByteCache", "archivedCache"},
115 {"java/lang/Short$ShortCache", "archivedCache"},
116 {"java/lang/Character$CharacterCache", "archivedCache"},
117 {"java/util/jar/Attributes$Name", "KNOWN_NAMES"},
118 {"sun/util/locale/BaseLocale", "constantBaseLocales"},
119 {"jdk/internal/module/ArchivedModuleGraph", "archivedModuleGraph"},
120 {"java/util/ImmutableCollections", "archivedObjects"},
121 {"java/lang/ModuleLayer", "EMPTY_LAYER"},
122 {"java/lang/module/Configuration", "EMPTY_CONFIGURATION"},
123 {"jdk/internal/math/FDBigInteger", "archivedCaches"},
124
125 #ifndef PRODUCT
126 {nullptr, nullptr}, // Extra slot for -XX:ArchiveHeapTestClass
127 #endif
128 {nullptr, nullptr},
129 };
130
131 // full module graph
132 static ArchivableStaticFieldInfo fmg_archive_subgraph_entry_fields[] = {
133 {"jdk/internal/loader/ArchivedClassLoaders", "archivedClassLoaders"},
134 {ARCHIVED_BOOT_LAYER_CLASS, ARCHIVED_BOOT_LAYER_FIELD},
135 {"java/lang/Module$ArchivedData", "archivedData"},
136 {nullptr, nullptr},
137 };
138
139 KlassSubGraphInfo* HeapShared::_dump_time_special_subgraph;
140 ArchivedKlassSubGraphInfoRecord* HeapShared::_run_time_special_subgraph;
141 GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = nullptr;
142 GrowableArrayCHeap<OopHandle, mtClassShared>* HeapShared::_root_segments = nullptr;
143 int HeapShared::_root_segment_max_size_elems;
144 OopHandle HeapShared::_scratch_basic_type_mirrors[T_VOID+1];
145 MetaspaceObjToOopHandleTable* HeapShared::_scratch_objects_table = nullptr;
146
147 static bool is_subgraph_root_class_of(ArchivableStaticFieldInfo fields[], InstanceKlass* ik) {
148 for (int i = 0; fields[i].valid(); i++) {
149 if (fields[i].klass == ik) {
150 return true;
151 }
152 }
153 return false;
154 }
155
156 bool HeapShared::is_subgraph_root_class(InstanceKlass* ik) {
157 return is_subgraph_root_class_of(archive_subgraph_entry_fields, ik) ||
158 is_subgraph_root_class_of(fmg_archive_subgraph_entry_fields, ik);
159 }
160
161 unsigned HeapShared::oop_hash(oop const& p) {
162 // Do not call p->identity_hash() as that will update the
163 // object header.
164 return primitive_hash(cast_from_oop<intptr_t>(p));
165 }
166
167 static void reset_states(oop obj, TRAPS) {
168 Handle h_obj(THREAD, obj);
169 InstanceKlass* klass = InstanceKlass::cast(obj->klass());
170 TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
171 Symbol* method_sig = vmSymbols::void_method_signature();
172
173 while (klass != nullptr) {
174 Method* method = klass->find_method(method_name, method_sig);
175 if (method != nullptr) {
176 assert(method->is_private(), "must be");
177 if (log_is_enabled(Debug, cds)) {
178 ResourceMark rm(THREAD);
179 log_debug(cds)(" calling %s", method->name_and_sig_as_C_string());
180 }
181 JavaValue result(T_VOID);
182 JavaCalls::call_special(&result, h_obj, klass,
183 method_name, method_sig, CHECK);
184 }
185 klass = klass->java_super();
186 }
187 }
188
189 void HeapShared::reset_archived_object_states(TRAPS) {
190 assert(CDSConfig::is_dumping_heap(), "dump-time only");
191 log_debug(cds)("Resetting platform loader");
192 reset_states(SystemDictionary::java_platform_loader(), CHECK);
193 log_debug(cds)("Resetting system loader");
194 reset_states(SystemDictionary::java_system_loader(), CHECK);
195
196 // Clean up jdk.internal.loader.ClassLoaders::bootLoader(), which is not
197 // directly used for class loading, but rather is used by the core library
198 // to keep track of resources, etc, loaded by the null class loader.
199 //
200 // Note, this object is non-null, and is not the same as
201 // ClassLoaderData::the_null_class_loader_data()->class_loader(),
202 // which is null.
203 log_debug(cds)("Resetting boot loader");
204 JavaValue result(T_OBJECT);
205 JavaCalls::call_static(&result,
206 vmClasses::jdk_internal_loader_ClassLoaders_klass(),
207 vmSymbols::bootLoader_name(),
208 vmSymbols::void_BuiltinClassLoader_signature(),
209 CHECK);
210 Handle boot_loader(THREAD, result.get_oop());
211 reset_states(boot_loader(), CHECK);
212 }
213
214 HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = nullptr;
215
216 bool HeapShared::has_been_archived(oop obj) {
217 assert(CDSConfig::is_dumping_heap(), "dump-time only");
218 return archived_object_cache()->get(obj) != nullptr;
219 }
220
221 int HeapShared::append_root(oop obj) {
222 assert(CDSConfig::is_dumping_heap(), "dump-time only");
223 if (obj != nullptr) {
224 assert(has_been_archived(obj), "must be");
225 }
226 // No GC should happen since we aren't scanning _pending_roots.
227 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
228
229 return _pending_roots->append(obj);
230 }
231
232 objArrayOop HeapShared::root_segment(int segment_idx) {
233 if (CDSConfig::is_dumping_heap()) {
234 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
235 } else {
236 assert(CDSConfig::is_using_archive(), "must be");
237 }
238
239 objArrayOop segment = (objArrayOop)_root_segments->at(segment_idx).resolve();
240 assert(segment != nullptr, "should have been initialized");
241 return segment;
242 }
243
244 void HeapShared::get_segment_indexes(int idx, int& seg_idx, int& int_idx) {
245 assert(_root_segment_max_size_elems > 0, "sanity");
246
247 // Try to avoid divisions for the common case.
248 if (idx < _root_segment_max_size_elems) {
249 seg_idx = 0;
250 int_idx = idx;
251 } else {
252 seg_idx = idx / _root_segment_max_size_elems;
253 int_idx = idx % _root_segment_max_size_elems;
254 }
255
256 assert(idx == seg_idx * _root_segment_max_size_elems + int_idx,
257 "sanity: %d index maps to %d segment and %d internal", idx, seg_idx, int_idx);
258 }
259
260 // Returns an objArray that contains all the roots of the archived objects
261 oop HeapShared::get_root(int index, bool clear) {
262 assert(index >= 0, "sanity");
263 assert(!CDSConfig::is_dumping_heap() && CDSConfig::is_using_archive(), "runtime only");
264 assert(!_root_segments->is_empty(), "must have loaded shared heap");
265 int seg_idx, int_idx;
266 get_segment_indexes(index, seg_idx, int_idx);
267 oop result = root_segment(seg_idx)->obj_at(int_idx);
268 if (clear) {
269 clear_root(index);
270 }
271 return result;
272 }
273
274 void HeapShared::clear_root(int index) {
275 assert(index >= 0, "sanity");
276 assert(CDSConfig::is_using_archive(), "must be");
277 if (ArchiveHeapLoader::is_in_use()) {
278 int seg_idx, int_idx;
279 get_segment_indexes(index, seg_idx, int_idx);
280 if (log_is_enabled(Debug, cds, heap)) {
281 oop old = root_segment(seg_idx)->obj_at(int_idx);
282 log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
283 }
284 root_segment(seg_idx)->obj_at_put(int_idx, nullptr);
285 }
286 }
287
288 bool HeapShared::archive_object(oop obj, oop referrer, KlassSubGraphInfo* subgraph_info) {
289 assert(CDSConfig::is_dumping_heap(), "dump-time only");
290
291 assert(!obj->is_stackChunk(), "do not archive stack chunks");
292 if (has_been_archived(obj)) {
293 return true;
294 }
295
296 if (ArchiveHeapWriter::is_too_large_to_archive(obj->size())) {
297 log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: %zu",
298 p2i(obj), obj->size());
299 debug_trace();
300 return false;
301 } else {
302 count_allocation(obj->size());
303 ArchiveHeapWriter::add_source_obj(obj);
304 CachedOopInfo info = make_cached_oop_info(obj, referrer);
305 archived_object_cache()->put_when_absent(obj, info);
306 archived_object_cache()->maybe_grow();
307 mark_native_pointers(obj);
308
309 Klass* k = obj->klass();
310 if (k->is_instance_klass()) {
311 // Whenever we see a non-array Java object of type X, we mark X to be aot-initialized.
312 // This ensures that during the production run, whenever Java code sees a cached object
313 // of type X, we know that X is already initialized. (see TODO comment below ...)
314
315 if (InstanceKlass::cast(k)->is_enum_subclass()
316 // We can't rerun <clinit> of enum classes (see cdsEnumKlass.cpp) so
317 // we must store them as AOT-initialized.
318 || (subgraph_info == _dump_time_special_subgraph))
319 // TODO: we do this only for the special subgraph for now. Extending this to
320 // other subgraphs would require more refactoring of the core library (such as
321 // move some initialization logic into runtimeSetup()).
322 //
323 // For the other subgraphs, we have a weaker mechanism to ensure that
324 // all classes in a subgraph are initialized before the subgraph is programmatically
325 // returned from jdk.internal.misc.CDS::initializeFromArchive().
326 // See HeapShared::initialize_from_archived_subgraph().
327 {
328 AOTArtifactFinder::add_aot_inited_class(InstanceKlass::cast(k));
329 }
330
331 if (java_lang_Class::is_instance(obj)) {
332 Klass* mirror_k = java_lang_Class::as_Klass(obj);
333 if (mirror_k != nullptr) {
334 AOTArtifactFinder::add_cached_class(mirror_k);
335 }
336 } else if (java_lang_invoke_ResolvedMethodName::is_instance(obj)) {
337 Method* m = java_lang_invoke_ResolvedMethodName::vmtarget(obj);
338 if (m != nullptr) {
339 InstanceKlass* method_holder = m->method_holder();
340 AOTArtifactFinder::add_cached_class(method_holder);
341 }
342 }
343 }
344
345 if (log_is_enabled(Debug, cds, heap)) {
346 ResourceMark rm;
347 LogTarget(Debug, cds, heap) log;
348 LogStream out(log);
349 out.print("Archived heap object " PTR_FORMAT " : %s ",
350 p2i(obj), obj->klass()->external_name());
351 if (java_lang_Class::is_instance(obj)) {
352 Klass* k = java_lang_Class::as_Klass(obj);
353 if (k != nullptr) {
354 out.print("%s", k->external_name());
355 } else {
356 out.print("primitive");
357 }
358 }
359 out.cr();
360 }
361
362 return true;
363 }
364 }
365
366 class MetaspaceObjToOopHandleTable: public ResourceHashtable<MetaspaceObj*, OopHandle,
367 36137, // prime number
368 AnyObj::C_HEAP,
369 mtClassShared> {
370 public:
371 oop get_oop(MetaspaceObj* ptr) {
372 MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
373 OopHandle* handle = get(ptr);
374 if (handle != nullptr) {
375 return handle->resolve();
376 } else {
377 return nullptr;
378 }
379 }
380 void set_oop(MetaspaceObj* ptr, oop o) {
381 MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
382 OopHandle handle(Universe::vm_global(), o);
383 bool is_new = put(ptr, handle);
384 assert(is_new, "cannot set twice");
385 }
386 void remove_oop(MetaspaceObj* ptr) {
387 MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
388 OopHandle* handle = get(ptr);
389 if (handle != nullptr) {
390 handle->release(Universe::vm_global());
391 remove(ptr);
392 }
393 }
394 };
395
396 void HeapShared::add_scratch_resolved_references(ConstantPool* src, objArrayOop dest) {
397 if (SystemDictionaryShared::is_builtin_loader(src->pool_holder()->class_loader_data())) {
398 _scratch_objects_table->set_oop(src, dest);
399 }
400 }
401
402 objArrayOop HeapShared::scratch_resolved_references(ConstantPool* src) {
403 return (objArrayOop)_scratch_objects_table->get_oop(src);
404 }
405
406 void HeapShared::init_dumping() {
407 _scratch_objects_table = new (mtClass)MetaspaceObjToOopHandleTable();
408 _pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
409 }
410
411 void HeapShared::init_scratch_objects_for_basic_type_mirrors(TRAPS) {
412 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
413 BasicType bt = (BasicType)i;
414 if (!is_reference_type(bt)) {
415 oop m = java_lang_Class::create_basic_type_mirror(type2name(bt), bt, CHECK);
416 _scratch_basic_type_mirrors[i] = OopHandle(Universe::vm_global(), m);
417 }
418 }
419 }
420
421 // Given java_mirror that represents a (primitive or reference) type T,
422 // return the "scratch" version that represents the same type T.
423 // Note that if java_mirror will be returned if it's already a
424 // scratch mirror.
425 //
426 // See java_lang_Class::create_scratch_mirror() for more info.
427 oop HeapShared::scratch_java_mirror(oop java_mirror) {
428 assert(java_lang_Class::is_instance(java_mirror), "must be");
429
430 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
431 BasicType bt = (BasicType)i;
432 if (!is_reference_type(bt)) {
433 if (_scratch_basic_type_mirrors[i].resolve() == java_mirror) {
434 return java_mirror;
435 }
436 }
437 }
438
439 if (java_lang_Class::is_primitive(java_mirror)) {
440 return scratch_java_mirror(java_lang_Class::as_BasicType(java_mirror));
441 } else {
442 return scratch_java_mirror(java_lang_Class::as_Klass(java_mirror));
443 }
444 }
445
446 oop HeapShared::scratch_java_mirror(BasicType t) {
447 assert((uint)t < T_VOID+1, "range check");
448 assert(!is_reference_type(t), "sanity");
449 return _scratch_basic_type_mirrors[t].resolve();
450 }
451
452 oop HeapShared::scratch_java_mirror(Klass* k) {
453 return _scratch_objects_table->get_oop(k);
454 }
455
456 void HeapShared::set_scratch_java_mirror(Klass* k, oop mirror) {
457 _scratch_objects_table->set_oop(k, mirror);
458 }
459
460 void HeapShared::remove_scratch_objects(Klass* k) {
461 // Klass is being deallocated. Java mirror can still be alive, and it should not
462 // point to dead klass. We need to break the link from mirror to the Klass.
463 // See how InstanceKlass::deallocate_contents does it for normal mirrors.
464 oop mirror = _scratch_objects_table->get_oop(k);
465 if (mirror != nullptr) {
466 java_lang_Class::set_klass(mirror, nullptr);
467 }
468 _scratch_objects_table->remove_oop(k);
469 if (k->is_instance_klass()) {
470 _scratch_objects_table->remove(InstanceKlass::cast(k)->constants());
471 }
472 }
473
474 //TODO: we eventually want a more direct test for these kinds of things.
475 //For example the JVM could record some bit of context from the creation
476 //of the klass, such as who called the hidden class factory. Using
477 //string compares on names is fragile and will break as soon as somebody
478 //changes the names in the JDK code. See discussion in JDK-8342481 for
479 //related ideas about marking AOT-related classes.
480 bool HeapShared::is_lambda_form_klass(InstanceKlass* ik) {
481 return ik->is_hidden() &&
482 (ik->name()->starts_with("java/lang/invoke/LambdaForm$MH+") ||
483 ik->name()->starts_with("java/lang/invoke/LambdaForm$DMH+") ||
484 ik->name()->starts_with("java/lang/invoke/LambdaForm$BMH+") ||
485 ik->name()->starts_with("java/lang/invoke/LambdaForm$VH+"));
486 }
487
488 bool HeapShared::is_lambda_proxy_klass(InstanceKlass* ik) {
489 return ik->is_hidden() && (ik->name()->index_of_at(0, "$$Lambda+", 9) > 0);
490 }
491
492 bool HeapShared::is_string_concat_klass(InstanceKlass* ik) {
493 return ik->is_hidden() && ik->name()->starts_with("java/lang/String$$StringConcat");
494 }
495
496 bool HeapShared::is_archivable_hidden_klass(InstanceKlass* ik) {
497 return CDSConfig::is_dumping_method_handles() &&
498 (is_lambda_form_klass(ik) || is_lambda_proxy_klass(ik) || is_string_concat_klass(ik));
499 }
500
501
502 void HeapShared::copy_and_rescan_aot_inited_mirror(InstanceKlass* ik) {
503 ik->set_has_aot_initialized_mirror();
504 if (AOTClassInitializer::is_runtime_setup_required(ik)) {
505 ik->set_is_runtime_setup_required();
506 }
507
508 oop orig_mirror = ik->java_mirror();
509 oop m = scratch_java_mirror(ik);
510 assert(ik->is_initialized(), "must be");
511
512 int nfields = 0;
513 for (JavaFieldStream fs(ik); !fs.done(); fs.next()) {
514 if (fs.access_flags().is_static()) {
515 fieldDescriptor& fd = fs.field_descriptor();
516 int offset = fd.offset();
517 switch (fd.field_type()) {
518 case T_OBJECT:
519 case T_ARRAY:
520 {
521 oop field_obj = orig_mirror->obj_field(offset);
522 if (offset == java_lang_Class::reflection_data_offset()) {
523 // Class::reflectData use SoftReference, which cannot be archived. Set it
524 // to null and it will be recreated at runtime.
525 field_obj = nullptr;
526 }
527 m->obj_field_put(offset, field_obj);
528 if (field_obj != nullptr) {
529 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, field_obj);
530 assert(success, "sanity");
531 }
532 }
533 break;
534 case T_BOOLEAN:
535 m->bool_field_put(offset, orig_mirror->bool_field(offset));
536 break;
537 case T_BYTE:
538 m->byte_field_put(offset, orig_mirror->byte_field(offset));
539 break;
540 case T_SHORT:
541 m->short_field_put(offset, orig_mirror->short_field(offset));
542 break;
543 case T_CHAR:
544 m->char_field_put(offset, orig_mirror->char_field(offset));
545 break;
546 case T_INT:
547 m->int_field_put(offset, orig_mirror->int_field(offset));
548 break;
549 case T_LONG:
550 m->long_field_put(offset, orig_mirror->long_field(offset));
551 break;
552 case T_FLOAT:
553 m->float_field_put(offset, orig_mirror->float_field(offset));
554 break;
555 case T_DOUBLE:
556 m->double_field_put(offset, orig_mirror->double_field(offset));
557 break;
558 default:
559 ShouldNotReachHere();
560 }
561 nfields ++;
562 }
563 }
564
565 oop class_data = java_lang_Class::class_data(orig_mirror);
566 java_lang_Class::set_class_data(m, class_data);
567 if (class_data != nullptr) {
568 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, class_data);
569 assert(success, "sanity");
570 }
571
572 if (log_is_enabled(Debug, cds, init)) {
573 ResourceMark rm;
574 log_debug(cds, init)("copied %3d field(s) in aot-initialized mirror %s%s%s", nfields, ik->external_name(),
575 ik->is_hidden() ? " (hidden)" : "",
576 ik->is_enum_subclass() ? " (enum)" : "");
577 }
578 }
579
580 static void copy_java_mirror_hashcode(oop orig_mirror, oop scratch_m) {
581 // We need to retain the identity_hash, because it may have been used by some hashtables
582 // in the shared heap.
583 if (!orig_mirror->fast_no_hash_check()) {
584 intptr_t src_hash = orig_mirror->identity_hash();
585 if (UseCompactObjectHeaders) {
586 narrowKlass nk = CompressedKlassPointers::encode(orig_mirror->klass());
587 scratch_m->set_mark(markWord::prototype().set_narrow_klass(nk).copy_set_hash(src_hash));
588 } else {
589 scratch_m->set_mark(markWord::prototype().copy_set_hash(src_hash));
590 }
591 assert(scratch_m->mark().is_unlocked(), "sanity");
592
593 DEBUG_ONLY(intptr_t archived_hash = scratch_m->identity_hash());
594 assert(src_hash == archived_hash, "Different hash codes: original " INTPTR_FORMAT ", archived " INTPTR_FORMAT, src_hash, archived_hash);
595 }
596 }
597
598 static objArrayOop get_archived_resolved_references(InstanceKlass* src_ik) {
599 if (SystemDictionaryShared::is_builtin_loader(src_ik->class_loader_data())) {
600 objArrayOop rr = src_ik->constants()->resolved_references_or_null();
601 if (rr != nullptr && !ArchiveHeapWriter::is_too_large_to_archive(rr)) {
602 return HeapShared::scratch_resolved_references(src_ik->constants());
603 }
604 }
605 return nullptr;
606 }
607
608 void HeapShared::archive_strings() {
609 oop shared_strings_array = StringTable::init_shared_strings_array(_dumped_interned_strings);
610 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, shared_strings_array);
611 // We must succeed because:
612 // - _dumped_interned_strings do not contain any large strings.
613 // - StringTable::init_shared_table() doesn't create any large arrays.
614 assert(success, "shared strings array must not point to arrays or strings that are too large to archive");
615 StringTable::set_shared_strings_array_index(append_root(shared_strings_array));
616 }
617
618 int HeapShared::archive_exception_instance(oop exception) {
619 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, exception);
620 assert(success, "sanity");
621 return append_root(exception);
622 }
623
624 void HeapShared::mark_native_pointers(oop orig_obj) {
625 if (java_lang_Class::is_instance(orig_obj)) {
626 ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::klass_offset());
627 ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::array_klass_offset());
628 } else if (java_lang_invoke_ResolvedMethodName::is_instance(orig_obj)) {
629 ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_invoke_ResolvedMethodName::vmtarget_offset());
630 }
631 }
632
633 void HeapShared::get_pointer_info(oop src_obj, bool& has_oop_pointers, bool& has_native_pointers) {
634 CachedOopInfo* info = archived_object_cache()->get(src_obj);
635 assert(info != nullptr, "must be");
636 has_oop_pointers = info->has_oop_pointers();
637 has_native_pointers = info->has_native_pointers();
638 }
639
640 void HeapShared::set_has_native_pointers(oop src_obj) {
641 CachedOopInfo* info = archived_object_cache()->get(src_obj);
642 assert(info != nullptr, "must be");
643 info->set_has_native_pointers();
644 }
645
646 // Between start_scanning_for_oops() and end_scanning_for_oops(), we discover all Java heap objects that
647 // should be stored in the AOT cache. The scanning is coordinated by AOTArtifactFinder.
648 void HeapShared::start_scanning_for_oops() {
649 {
650 NoSafepointVerifier nsv;
651
652 // The special subgraph doesn't belong to any class. We use Object_klass() here just
653 // for convenience.
654 _dump_time_special_subgraph = init_subgraph_info(vmClasses::Object_klass(), false);
655
656 // Cache for recording where the archived objects are copied to
657 create_archived_object_cache();
658
659 if (UseCompressedOops || UseG1GC) {
660 log_info(cds)("Heap range = [" PTR_FORMAT " - " PTR_FORMAT "]",
661 UseCompressedOops ? p2i(CompressedOops::begin()) :
662 p2i((address)G1CollectedHeap::heap()->reserved().start()),
663 UseCompressedOops ? p2i(CompressedOops::end()) :
664 p2i((address)G1CollectedHeap::heap()->reserved().end()));
665 }
666
667 archive_subgraphs();
668 }
669
670 init_seen_objects_table();
671 Universe::archive_exception_instances();
672 }
673
674 void HeapShared::end_scanning_for_oops() {
675 archive_strings();
676 delete_seen_objects_table();
677 }
678
679 void HeapShared::write_heap(ArchiveHeapInfo *heap_info) {
680 {
681 NoSafepointVerifier nsv;
682 CDSHeapVerifier::verify();
683 check_special_subgraph_classes();
684 }
685
686 StringTable::write_shared_table(_dumped_interned_strings);
687 ArchiveHeapWriter::write(_pending_roots, heap_info);
688
689 ArchiveBuilder::OtherROAllocMark mark;
690 write_subgraph_info_table();
691 }
692
693 void HeapShared::scan_java_mirror(oop orig_mirror) {
694 oop m = scratch_java_mirror(orig_mirror);
695 if (m != nullptr) { // nullptr if for custom class loader
696 copy_java_mirror_hashcode(orig_mirror, m);
697 bool success = archive_reachable_objects_from(1, _dump_time_special_subgraph, m);
698 assert(success, "sanity");
699 }
700 }
701
702 void HeapShared::scan_java_class(Klass* orig_k) {
703 scan_java_mirror(orig_k->java_mirror());
704
705 if (orig_k->is_instance_klass()) {
706 InstanceKlass* orig_ik = InstanceKlass::cast(orig_k);
707 orig_ik->constants()->prepare_resolved_references_for_archiving();
708 objArrayOop rr = get_archived_resolved_references(orig_ik);
709 if (rr != nullptr) {
710 bool success = HeapShared::archive_reachable_objects_from(1, _dump_time_special_subgraph, rr);
711 assert(success, "must be");
712 }
713
714 orig_ik->constants()->add_dumped_interned_strings();
715 }
716 }
717
718 void HeapShared::archive_subgraphs() {
719 assert(CDSConfig::is_dumping_heap(), "must be");
720
721 archive_object_subgraphs(archive_subgraph_entry_fields,
722 false /* is_full_module_graph */);
723
724 if (CDSConfig::is_dumping_full_module_graph()) {
725 archive_object_subgraphs(fmg_archive_subgraph_entry_fields,
726 true /* is_full_module_graph */);
727 Modules::verify_archived_modules();
728 }
729 }
730
731 //
732 // Subgraph archiving support
733 //
734 HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = nullptr;
735 HeapShared::RunTimeKlassSubGraphInfoTable HeapShared::_run_time_subgraph_info_table;
736
737 // Get the subgraph_info for Klass k. A new subgraph_info is created if
738 // there is no existing one for k. The subgraph_info records the "buffered"
739 // address of the class.
740 KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
741 assert(CDSConfig::is_dumping_heap(), "dump time only");
742 bool created;
743 KlassSubGraphInfo* info =
744 _dump_time_subgraph_info_table->put_if_absent(k, KlassSubGraphInfo(k, is_full_module_graph),
745 &created);
746 assert(created, "must not initialize twice");
747 return info;
748 }
749
750 KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
751 assert(CDSConfig::is_dumping_heap(), "dump time only");
752 KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
753 assert(info != nullptr, "must have been initialized");
754 return info;
755 }
756
757 // Add an entry field to the current KlassSubGraphInfo.
758 void KlassSubGraphInfo::add_subgraph_entry_field(int static_field_offset, oop v) {
759 assert(CDSConfig::is_dumping_heap(), "dump time only");
760 if (_subgraph_entry_fields == nullptr) {
761 _subgraph_entry_fields =
762 new (mtClass) GrowableArray<int>(10, mtClass);
763 }
764 _subgraph_entry_fields->append(static_field_offset);
765 _subgraph_entry_fields->append(HeapShared::append_root(v));
766 }
767
768 // Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
769 // Only objects of boot classes can be included in sub-graph.
770 void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
771 assert(CDSConfig::is_dumping_heap(), "dump time only");
772
773 if (_subgraph_object_klasses == nullptr) {
774 _subgraph_object_klasses =
775 new (mtClass) GrowableArray<Klass*>(50, mtClass);
776 }
777
778 if (_k == orig_k) {
779 // Don't add the Klass containing the sub-graph to it's own klass
780 // initialization list.
781 return;
782 }
783
784 if (orig_k->is_instance_klass()) {
785 #ifdef ASSERT
786 InstanceKlass* ik = InstanceKlass::cast(orig_k);
787 if (CDSConfig::is_dumping_method_handles()) {
788 // -XX:AOTInitTestClass must be used carefully in regression tests to
789 // include only classes that are safe to aot-initialize.
790 assert(ik->class_loader() == nullptr ||
791 HeapShared::is_lambda_proxy_klass(ik) ||
792 AOTClassInitializer::has_test_class(),
793 "we can archive only instances of boot classes or lambda proxy classes");
794 } else {
795 assert(ik->class_loader() == nullptr, "must be boot class");
796 }
797 #endif
798 // vmClasses::xxx_klass() are not updated, need to check
799 // the original Klass*
800 if (orig_k == vmClasses::String_klass() ||
801 orig_k == vmClasses::Object_klass()) {
802 // Initialized early during VM initialization. No need to be added
803 // to the sub-graph object class list.
804 return;
805 }
806 check_allowed_klass(InstanceKlass::cast(orig_k));
807 } else if (orig_k->is_objArray_klass()) {
808 Klass* abk = ObjArrayKlass::cast(orig_k)->bottom_klass();
809 if (abk->is_instance_klass()) {
810 assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
811 "must be boot class");
812 check_allowed_klass(InstanceKlass::cast(ObjArrayKlass::cast(orig_k)->bottom_klass()));
813 }
814 if (orig_k == Universe::objectArrayKlass()) {
815 // Initialized early during Universe::genesis. No need to be added
816 // to the list.
817 return;
818 }
819 } else {
820 assert(orig_k->is_typeArray_klass(), "must be");
821 // Primitive type arrays are created early during Universe::genesis.
822 return;
823 }
824
825 if (log_is_enabled(Debug, cds, heap)) {
826 if (!_subgraph_object_klasses->contains(orig_k)) {
827 ResourceMark rm;
828 log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
829 }
830 }
831
832 _subgraph_object_klasses->append_if_missing(orig_k);
833 _has_non_early_klasses |= is_non_early_klass(orig_k);
834 }
835
836 void KlassSubGraphInfo::check_allowed_klass(InstanceKlass* ik) {
837 #ifndef PRODUCT
838 if (AOTClassInitializer::has_test_class()) {
839 // The tests can cache arbitrary types of objects.
840 return;
841 }
842 #endif
843
844 if (ik->module()->name() == vmSymbols::java_base()) {
845 assert(ik->package() != nullptr, "classes in java.base cannot be in unnamed package");
846 return;
847 }
848
849 const char* lambda_msg = "";
850 if (CDSConfig::is_dumping_method_handles()) {
851 lambda_msg = ", or a lambda proxy class";
852 if (HeapShared::is_lambda_proxy_klass(ik) &&
853 (ik->class_loader() == nullptr ||
854 ik->class_loader() == SystemDictionary::java_platform_loader() ||
855 ik->class_loader() == SystemDictionary::java_system_loader())) {
856 return;
857 }
858 }
859
860 #ifndef PRODUCT
861 if (!ik->module()->is_named() && ik->package() == nullptr && ArchiveHeapTestClass != nullptr) {
862 // This class is loaded by ArchiveHeapTestClass
863 return;
864 }
865 const char* testcls_msg = ", or a test class in an unnamed package of an unnamed module";
866 #else
867 const char* testcls_msg = "";
868 #endif
869
870 ResourceMark rm;
871 log_error(cds, heap)("Class %s not allowed in archive heap. Must be in java.base%s%s",
872 ik->external_name(), lambda_msg, testcls_msg);
873 MetaspaceShared::unrecoverable_writing_error();
874 }
875
876 bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
877 if (k->is_objArray_klass()) {
878 k = ObjArrayKlass::cast(k)->bottom_klass();
879 }
880 if (k->is_instance_klass()) {
881 if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
882 ResourceMark rm;
883 log_info(cds, heap)("non-early: %s", k->external_name());
884 return true;
885 } else {
886 return false;
887 }
888 } else {
889 return false;
890 }
891 }
892
893 // Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
894 void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
895 _k = ArchiveBuilder::get_buffered_klass(info->klass());
896 _entry_field_records = nullptr;
897 _subgraph_object_klasses = nullptr;
898 _is_full_module_graph = info->is_full_module_graph();
899
900 if (_is_full_module_graph) {
901 // Consider all classes referenced by the full module graph as early -- we will be
902 // allocating objects of these classes during JVMTI early phase, so they cannot
903 // be processed by (non-early) JVMTI ClassFileLoadHook
904 _has_non_early_klasses = false;
905 } else {
906 _has_non_early_klasses = info->has_non_early_klasses();
907 }
908
909 if (_has_non_early_klasses) {
910 ResourceMark rm;
911 log_info(cds, heap)(
912 "Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
913 _k->external_name());
914 }
915
916 // populate the entry fields
917 GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
918 if (entry_fields != nullptr) {
919 int num_entry_fields = entry_fields->length();
920 assert(num_entry_fields % 2 == 0, "sanity");
921 _entry_field_records =
922 ArchiveBuilder::new_ro_array<int>(num_entry_fields);
923 for (int i = 0 ; i < num_entry_fields; i++) {
924 _entry_field_records->at_put(i, entry_fields->at(i));
925 }
926 }
927
928 // <recorded_klasses> has the Klasses of all the objects that are referenced by this subgraph.
929 // Copy those that need to be explicitly initialized into <_subgraph_object_klasses>.
930 GrowableArray<Klass*>* recorded_klasses = info->subgraph_object_klasses();
931 if (recorded_klasses != nullptr) {
932 // AOT-inited classes are automatically marked as "initialized" during bootstrap. When
933 // programmatically loading a subgraph, we only need to explicitly initialize the classes
934 // that are not aot-inited.
935 int num_to_copy = 0;
936 for (int i = 0; i < recorded_klasses->length(); i++) {
937 Klass* subgraph_k = ArchiveBuilder::get_buffered_klass(recorded_klasses->at(i));
938 if (!subgraph_k->has_aot_initialized_mirror()) {
939 num_to_copy ++;
940 }
941 }
942
943 _subgraph_object_klasses = ArchiveBuilder::new_ro_array<Klass*>(num_to_copy);
944 bool is_special = (_k == ArchiveBuilder::get_buffered_klass(vmClasses::Object_klass()));
945 for (int i = 0, n = 0; i < recorded_klasses->length(); i++) {
946 Klass* subgraph_k = ArchiveBuilder::get_buffered_klass(recorded_klasses->at(i));
947 if (subgraph_k->has_aot_initialized_mirror()) {
948 continue;
949 }
950 if (log_is_enabled(Info, cds, heap)) {
951 ResourceMark rm;
952 const char* owner_name = is_special ? "<special>" : _k->external_name();
953 if (subgraph_k->is_instance_klass()) {
954 InstanceKlass* src_ik = InstanceKlass::cast(ArchiveBuilder::current()->get_source_addr(subgraph_k));
955 }
956 log_info(cds, heap)(
957 "Archived object klass %s (%2d) => %s",
958 owner_name, n, subgraph_k->external_name());
959 }
960 _subgraph_object_klasses->at_put(n, subgraph_k);
961 ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(n));
962 n++;
963 }
964 }
965
966 ArchivePtrMarker::mark_pointer(&_k);
967 ArchivePtrMarker::mark_pointer(&_entry_field_records);
968 ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
969 }
970
971 class HeapShared::CopyKlassSubGraphInfoToArchive : StackObj {
972 CompactHashtableWriter* _writer;
973 public:
974 CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
975
976 bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
977 if (info.subgraph_object_klasses() != nullptr || info.subgraph_entry_fields() != nullptr) {
978 ArchivedKlassSubGraphInfoRecord* record = HeapShared::archive_subgraph_info(&info);
979 Klass* buffered_k = ArchiveBuilder::get_buffered_klass(klass);
980 unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary((address)buffered_k);
981 u4 delta = ArchiveBuilder::current()->any_to_offset_u4(record);
982 _writer->add(hash, delta);
983 }
984 return true; // keep on iterating
985 }
986 };
987
988 ArchivedKlassSubGraphInfoRecord* HeapShared::archive_subgraph_info(KlassSubGraphInfo* info) {
989 ArchivedKlassSubGraphInfoRecord* record =
990 (ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
991 record->init(info);
992 if (info == _dump_time_special_subgraph) {
993 _run_time_special_subgraph = record;
994 }
995 return record;
996 }
997
998 // Build the records of archived subgraph infos, which include:
999 // - Entry points to all subgraphs from the containing class mirror. The entry
1000 // points are static fields in the mirror. For each entry point, the field
1001 // offset, and value are recorded in the sub-graph
1002 // info. The value is stored back to the corresponding field at runtime.
1003 // - A list of klasses that need to be loaded/initialized before archived
1004 // java object sub-graph can be accessed at runtime.
1005 void HeapShared::write_subgraph_info_table() {
1006 // Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
1007 DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
1008 CompactHashtableStats stats;
1009
1010 _run_time_subgraph_info_table.reset();
1011
1012 CompactHashtableWriter writer(d_table->_count, &stats);
1013 CopyKlassSubGraphInfoToArchive copy(&writer);
1014 d_table->iterate(©);
1015 writer.dump(&_run_time_subgraph_info_table, "subgraphs");
1016
1017 #ifndef PRODUCT
1018 if (ArchiveHeapTestClass != nullptr) {
1019 size_t len = strlen(ArchiveHeapTestClass) + 1;
1020 Array<char>* array = ArchiveBuilder::new_ro_array<char>((int)len);
1021 strncpy(array->adr_at(0), ArchiveHeapTestClass, len);
1022 _archived_ArchiveHeapTestClass = array;
1023 }
1024 #endif
1025 if (log_is_enabled(Info, cds, heap)) {
1026 print_stats();
1027 }
1028 }
1029
1030 void HeapShared::add_root_segment(objArrayOop segment_oop) {
1031 assert(segment_oop != nullptr, "must be");
1032 assert(ArchiveHeapLoader::is_in_use(), "must be");
1033 if (_root_segments == nullptr) {
1034 _root_segments = new GrowableArrayCHeap<OopHandle, mtClassShared>(10);
1035 }
1036 _root_segments->push(OopHandle(Universe::vm_global(), segment_oop));
1037 }
1038
1039 void HeapShared::init_root_segment_sizes(int max_size_elems) {
1040 _root_segment_max_size_elems = max_size_elems;
1041 }
1042
1043 void HeapShared::serialize_tables(SerializeClosure* soc) {
1044
1045 #ifndef PRODUCT
1046 soc->do_ptr(&_archived_ArchiveHeapTestClass);
1047 if (soc->reading() && _archived_ArchiveHeapTestClass != nullptr) {
1048 _test_class_name = _archived_ArchiveHeapTestClass->adr_at(0);
1049 setup_test_class(_test_class_name);
1050 }
1051 #endif
1052
1053 _run_time_subgraph_info_table.serialize_header(soc);
1054 soc->do_ptr(&_run_time_special_subgraph);
1055 }
1056
1057 static void verify_the_heap(Klass* k, const char* which) {
1058 if (VerifyArchivedFields > 0) {
1059 ResourceMark rm;
1060 log_info(cds, heap)("Verify heap %s initializing static field(s) in %s",
1061 which, k->external_name());
1062
1063 VM_Verify verify_op;
1064 VMThread::execute(&verify_op);
1065
1066 if (VerifyArchivedFields > 1 && is_init_completed()) {
1067 // At this time, the oop->klass() of some archived objects in the heap may not
1068 // have been loaded into the system dictionary yet. Nevertheless, oop->klass() should
1069 // have enough information (object size, oop maps, etc) so that a GC can be safely
1070 // performed.
1071 //
1072 // -XX:VerifyArchivedFields=2 force a GC to happen in such an early stage
1073 // to check for GC safety.
1074 log_info(cds, heap)("Trigger GC %s initializing static field(s) in %s",
1075 which, k->external_name());
1076 FlagSetting fs1(VerifyBeforeGC, true);
1077 FlagSetting fs2(VerifyDuringGC, true);
1078 FlagSetting fs3(VerifyAfterGC, true);
1079 Universe::heap()->collect(GCCause::_java_lang_system_gc);
1080 }
1081 }
1082 }
1083
1084 // Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
1085 // have a valid klass. I.e., oopDesc::klass() must have already been resolved.
1086 //
1087 // Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
1088 // ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
1089 // this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
1090 void HeapShared::resolve_classes(JavaThread* current) {
1091 assert(CDSConfig::is_using_archive(), "runtime only!");
1092 if (!ArchiveHeapLoader::is_in_use()) {
1093 return; // nothing to do
1094 }
1095 resolve_classes_for_subgraphs(current, archive_subgraph_entry_fields);
1096 resolve_classes_for_subgraphs(current, fmg_archive_subgraph_entry_fields);
1097 }
1098
1099 void HeapShared::resolve_classes_for_subgraphs(JavaThread* current, ArchivableStaticFieldInfo fields[]) {
1100 for (int i = 0; fields[i].valid(); i++) {
1101 ArchivableStaticFieldInfo* info = &fields[i];
1102 TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
1103 InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
1104 assert(k != nullptr && k->is_shared_boot_class(), "sanity");
1105 resolve_classes_for_subgraph_of(current, k);
1106 }
1107 }
1108
1109 void HeapShared::resolve_classes_for_subgraph_of(JavaThread* current, Klass* k) {
1110 JavaThread* THREAD = current;
1111 ExceptionMark em(THREAD);
1112 const ArchivedKlassSubGraphInfoRecord* record =
1113 resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
1114 if (HAS_PENDING_EXCEPTION) {
1115 CLEAR_PENDING_EXCEPTION;
1116 }
1117 if (record == nullptr) {
1118 clear_archived_roots_of(k);
1119 }
1120 }
1121
1122 void HeapShared::initialize_java_lang_invoke(TRAPS) {
1123 if (CDSConfig::is_using_aot_linked_classes() || CDSConfig::is_dumping_method_handles()) {
1124 resolve_or_init("java/lang/invoke/Invokers$Holder", true, CHECK);
1125 resolve_or_init("java/lang/invoke/MethodHandle", true, CHECK);
1126 resolve_or_init("java/lang/invoke/MethodHandleNatives", true, CHECK);
1127 resolve_or_init("java/lang/invoke/DirectMethodHandle$Holder", true, CHECK);
1128 resolve_or_init("java/lang/invoke/DelegatingMethodHandle$Holder", true, CHECK);
1129 resolve_or_init("java/lang/invoke/LambdaForm$Holder", true, CHECK);
1130 resolve_or_init("java/lang/invoke/BoundMethodHandle$Species_L", true, CHECK);
1131 }
1132 }
1133
1134 // Initialize the InstanceKlasses of objects that are reachable from the following roots:
1135 // - interned strings
1136 // - Klass::java_mirror() -- including aot-initialized mirrors such as those of Enum klasses.
1137 // - ConstantPool::resolved_references()
1138 // - Universe::<xxx>_exception_instance()
1139 //
1140 // For example, if this enum class is initialized at AOT cache assembly time:
1141 //
1142 // enum Fruit {
1143 // APPLE, ORANGE, BANANA;
1144 // static final Set<Fruit> HAVE_SEEDS = new HashSet<>(Arrays.asList(APPLE, ORANGE));
1145 // }
1146 //
1147 // the aot-initialized mirror of Fruit has a static field that references HashSet, which
1148 // should be initialized before any Java code can access the Fruit class. Note that
1149 // HashSet itself doesn't necessary need to be an aot-initialized class.
1150 void HeapShared::init_classes_for_special_subgraph(Handle class_loader, TRAPS) {
1151 if (!ArchiveHeapLoader::is_in_use()) {
1152 return;
1153 }
1154
1155 assert( _run_time_special_subgraph != nullptr, "must be");
1156 Array<Klass*>* klasses = _run_time_special_subgraph->subgraph_object_klasses();
1157 if (klasses != nullptr) {
1158 for (int pass = 0; pass < 2; pass ++) {
1159 for (int i = 0; i < klasses->length(); i++) {
1160 Klass* k = klasses->at(i);
1161 if (k->class_loader_data() == nullptr) {
1162 // This class is not yet loaded. We will initialize it in a later phase.
1163 // For example, we have loaded only AOTLinkedClassCategory::BOOT1 classes
1164 // but k is part of AOTLinkedClassCategory::BOOT2.
1165 continue;
1166 }
1167 if (k->class_loader() == class_loader()) {
1168 if (pass == 0) {
1169 if (k->is_instance_klass()) {
1170 InstanceKlass::cast(k)->link_class(CHECK);
1171 }
1172 } else {
1173 resolve_or_init(k, /*do_init*/true, CHECK);
1174 }
1175 }
1176 }
1177 }
1178 }
1179 }
1180
1181 void HeapShared::initialize_from_archived_subgraph(JavaThread* current, Klass* k) {
1182 JavaThread* THREAD = current;
1183 if (!ArchiveHeapLoader::is_in_use()) {
1184 return; // nothing to do
1185 }
1186
1187 if (k->name()->equals("jdk/internal/module/ArchivedModuleGraph") &&
1188 !CDSConfig::is_using_optimized_module_handling() &&
1189 // archive was created with --module-path
1190 AOTClassLocationConfig::runtime()->num_module_paths() > 0) {
1191 // ArchivedModuleGraph was created with a --module-path that's different than the runtime --module-path.
1192 // Thus, it might contain references to modules that do not exist at runtime. We cannot use it.
1193 log_info(cds, heap)("Skip initializing ArchivedModuleGraph subgraph: is_using_optimized_module_handling=%s num_module_paths=%d",
1194 BOOL_TO_STR(CDSConfig::is_using_optimized_module_handling()),
1195 AOTClassLocationConfig::runtime()->num_module_paths());
1196 return;
1197 }
1198
1199 ExceptionMark em(THREAD);
1200 const ArchivedKlassSubGraphInfoRecord* record =
1201 resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
1202
1203 if (HAS_PENDING_EXCEPTION) {
1204 CLEAR_PENDING_EXCEPTION;
1205 // None of the field value will be set if there was an exception when initializing the classes.
1206 // The java code will not see any of the archived objects in the
1207 // subgraphs referenced from k in this case.
1208 return;
1209 }
1210
1211 if (record != nullptr) {
1212 init_archived_fields_for(k, record);
1213 }
1214 }
1215
1216 const ArchivedKlassSubGraphInfoRecord*
1217 HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
1218 assert(!CDSConfig::is_dumping_heap(), "Should not be called when dumping heap");
1219
1220 if (!k->is_shared()) {
1221 return nullptr;
1222 }
1223 unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
1224 const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
1225
1226 #ifndef PRODUCT
1227 if (_test_class_name != nullptr && k->name()->equals(_test_class_name) && record != nullptr) {
1228 _test_class = k;
1229 _test_class_record = record;
1230 }
1231 #endif
1232
1233 // Initialize from archived data. Currently this is done only
1234 // during VM initialization time. No lock is needed.
1235 if (record == nullptr) {
1236 if (log_is_enabled(Info, cds, heap)) {
1237 ResourceMark rm(THREAD);
1238 log_info(cds, heap)("subgraph %s is not recorded",
1239 k->external_name());
1240 }
1241 return nullptr;
1242 } else {
1243 if (record->is_full_module_graph() && !CDSConfig::is_using_full_module_graph()) {
1244 if (log_is_enabled(Info, cds, heap)) {
1245 ResourceMark rm(THREAD);
1246 log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
1247 k->external_name());
1248 }
1249 return nullptr;
1250 }
1251
1252 if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
1253 if (log_is_enabled(Info, cds, heap)) {
1254 ResourceMark rm(THREAD);
1255 log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
1256 k->external_name());
1257 }
1258 return nullptr;
1259 }
1260
1261 if (log_is_enabled(Info, cds, heap)) {
1262 ResourceMark rm;
1263 log_info(cds, heap)("%s subgraph %s ", do_init ? "init" : "resolve", k->external_name());
1264 }
1265
1266 resolve_or_init(k, do_init, CHECK_NULL);
1267
1268 // Load/link/initialize the klasses of the objects in the subgraph.
1269 // nullptr class loader is used.
1270 Array<Klass*>* klasses = record->subgraph_object_klasses();
1271 if (klasses != nullptr) {
1272 for (int i = 0; i < klasses->length(); i++) {
1273 Klass* klass = klasses->at(i);
1274 if (!klass->is_shared()) {
1275 return nullptr;
1276 }
1277 resolve_or_init(klass, do_init, CHECK_NULL);
1278 }
1279 }
1280 }
1281
1282 return record;
1283 }
1284
1285 void HeapShared::resolve_or_init(const char* klass_name, bool do_init, TRAPS) {
1286 TempNewSymbol klass_name_sym = SymbolTable::new_symbol(klass_name);
1287 InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name_sym);
1288 if (k == nullptr) {
1289 return;
1290 }
1291 assert(k->is_shared_boot_class(), "sanity");
1292 resolve_or_init(k, false, CHECK);
1293 if (do_init) {
1294 resolve_or_init(k, true, CHECK);
1295 }
1296 }
1297
1298 void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
1299 if (!do_init) {
1300 if (k->class_loader_data() == nullptr) {
1301 Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
1302 assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
1303 }
1304 } else {
1305 assert(k->class_loader_data() != nullptr, "must have been resolved by HeapShared::resolve_classes");
1306 if (k->is_instance_klass()) {
1307 InstanceKlass* ik = InstanceKlass::cast(k);
1308 ik->initialize(CHECK);
1309 } else if (k->is_objArray_klass()) {
1310 ObjArrayKlass* oak = ObjArrayKlass::cast(k);
1311 oak->initialize(CHECK);
1312 }
1313 }
1314 }
1315
1316 void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record) {
1317 verify_the_heap(k, "before");
1318
1319 // Load the subgraph entry fields from the record and store them back to
1320 // the corresponding fields within the mirror.
1321 oop m = k->java_mirror();
1322 Array<int>* entry_field_records = record->entry_field_records();
1323 if (entry_field_records != nullptr) {
1324 int efr_len = entry_field_records->length();
1325 assert(efr_len % 2 == 0, "sanity");
1326 for (int i = 0; i < efr_len; i += 2) {
1327 int field_offset = entry_field_records->at(i);
1328 int root_index = entry_field_records->at(i+1);
1329 oop v = get_root(root_index, /*clear=*/true);
1330 if (k->has_aot_initialized_mirror()) {
1331 assert(v == m->obj_field(field_offset), "must be aot-initialized");
1332 } else {
1333 m->obj_field_put(field_offset, v);
1334 }
1335 log_debug(cds, heap)(" " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
1336 }
1337
1338 // Done. Java code can see the archived sub-graphs referenced from k's
1339 // mirror after this point.
1340 if (log_is_enabled(Info, cds, heap)) {
1341 ResourceMark rm;
1342 log_info(cds, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s%s",
1343 k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "",
1344 k->has_aot_initialized_mirror() ? " (aot-inited)" : "");
1345 }
1346 }
1347
1348 verify_the_heap(k, "after ");
1349 }
1350
1351 void HeapShared::clear_archived_roots_of(Klass* k) {
1352 unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
1353 const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
1354 if (record != nullptr) {
1355 Array<int>* entry_field_records = record->entry_field_records();
1356 if (entry_field_records != nullptr) {
1357 int efr_len = entry_field_records->length();
1358 assert(efr_len % 2 == 0, "sanity");
1359 for (int i = 0; i < efr_len; i += 2) {
1360 int root_index = entry_field_records->at(i+1);
1361 clear_root(root_index);
1362 }
1363 }
1364 }
1365 }
1366
1367 // Push all oop fields (or oop array elemenets in case of an objArray) in
1368 // _referencing_obj onto the _stack.
1369 class HeapShared::OopFieldPusher: public BasicOopIterateClosure {
1370 PendingOopStack* _stack;
1371 GrowableArray<oop> _found_oop_fields;
1372 int _level;
1373 bool _record_klasses_only;
1374 KlassSubGraphInfo* _subgraph_info;
1375 oop _referencing_obj;
1376 bool _is_java_lang_ref;
1377 public:
1378 OopFieldPusher(PendingOopStack* stack,
1379 int level,
1380 bool record_klasses_only,
1381 KlassSubGraphInfo* subgraph_info,
1382 oop orig) :
1383 _stack(stack),
1384 _found_oop_fields(),
1385 _level(level),
1386 _record_klasses_only(record_klasses_only),
1387 _subgraph_info(subgraph_info),
1388 _referencing_obj(orig) {
1389 _is_java_lang_ref = AOTReferenceObjSupport::check_if_ref_obj(orig);
1390 }
1391 void do_oop(narrowOop *p) { OopFieldPusher::do_oop_work(p); }
1392 void do_oop( oop *p) { OopFieldPusher::do_oop_work(p); }
1393
1394 ~OopFieldPusher() {
1395 while (_found_oop_fields.length() > 0) {
1396 // This produces the exact same traversal order as the previous version
1397 // of OopFieldPusher that recurses on the C stack -- a depth-first search,
1398 // walking the oop fields in _referencing_obj by ascending field offsets.
1399 oop obj = _found_oop_fields.pop();
1400 _stack->push(PendingOop(obj, _referencing_obj, _level + 1));
1401 }
1402 }
1403
1404 protected:
1405 template <class T> void do_oop_work(T *p) {
1406 int field_offset = pointer_delta_as_int((char*)p, cast_from_oop<char*>(_referencing_obj));
1407 oop obj = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_load_at(_referencing_obj, field_offset);
1408 if (!CompressedOops::is_null(obj)) {
1409 if (_is_java_lang_ref && AOTReferenceObjSupport::skip_field(field_offset)) {
1410 // Do not follow these fields. They will be cleared to null.
1411 return;
1412 }
1413
1414 if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
1415 ResourceMark rm;
1416 log_debug(cds, heap)("(%d) %s[%d] ==> " PTR_FORMAT " size %zu %s", _level,
1417 _referencing_obj->klass()->external_name(), field_offset,
1418 p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
1419 if (log_is_enabled(Trace, cds, heap)) {
1420 LogTarget(Trace, cds, heap) log;
1421 LogStream out(log);
1422 obj->print_on(&out);
1423 }
1424 }
1425
1426 _found_oop_fields.push(obj);
1427 }
1428 }
1429
1430 public:
1431 oop referencing_obj() { return _referencing_obj; }
1432 KlassSubGraphInfo* subgraph_info() { return _subgraph_info; }
1433 };
1434
1435 // Checks if an oop has any non-null oop fields
1436 class PointsToOopsChecker : public BasicOopIterateClosure {
1437 bool _result;
1438
1439 template <class T> void check(T *p) {
1440 _result |= (HeapAccess<>::oop_load(p) != nullptr);
1441 }
1442
1443 public:
1444 PointsToOopsChecker() : _result(false) {}
1445 void do_oop(narrowOop *p) { check(p); }
1446 void do_oop( oop *p) { check(p); }
1447 bool result() { return _result; }
1448 };
1449
1450 HeapShared::CachedOopInfo HeapShared::make_cached_oop_info(oop obj, oop referrer) {
1451 PointsToOopsChecker points_to_oops_checker;
1452 obj->oop_iterate(&points_to_oops_checker);
1453 return CachedOopInfo(referrer, points_to_oops_checker.result());
1454 }
1455
1456 void HeapShared::init_box_classes(TRAPS) {
1457 if (ArchiveHeapLoader::is_in_use()) {
1458 vmClasses::Boolean_klass()->initialize(CHECK);
1459 vmClasses::Character_klass()->initialize(CHECK);
1460 vmClasses::Float_klass()->initialize(CHECK);
1461 vmClasses::Double_klass()->initialize(CHECK);
1462 vmClasses::Byte_klass()->initialize(CHECK);
1463 vmClasses::Short_klass()->initialize(CHECK);
1464 vmClasses::Integer_klass()->initialize(CHECK);
1465 vmClasses::Long_klass()->initialize(CHECK);
1466 vmClasses::Void_klass()->initialize(CHECK);
1467 }
1468 }
1469
1470 // (1) If orig_obj has not been archived yet, archive it.
1471 // (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
1472 // trace all objects that are reachable from it, and make sure these objects are archived.
1473 // (3) Record the klasses of all objects that are reachable from orig_obj (including those that
1474 // were already archived when this function is called)
1475 bool HeapShared::archive_reachable_objects_from(int level,
1476 KlassSubGraphInfo* subgraph_info,
1477 oop orig_obj) {
1478 assert(orig_obj != nullptr, "must be");
1479 PendingOopStack stack;
1480 stack.push(PendingOop(orig_obj, nullptr, level));
1481
1482 while (stack.length() > 0) {
1483 PendingOop po = stack.pop();
1484 _object_being_archived = po;
1485 bool status = walk_one_object(&stack, po.level(), subgraph_info, po.obj(), po.referrer());
1486 _object_being_archived = PendingOop();
1487
1488 if (!status) {
1489 // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1490 // as the Java code will take care of initializing this field dynamically.
1491 assert(level == 1, "VM should have exited with unarchivable objects for _level > 1");
1492 return false;
1493 }
1494 }
1495
1496 return true;
1497 }
1498
1499 bool HeapShared::walk_one_object(PendingOopStack* stack, int level, KlassSubGraphInfo* subgraph_info,
1500 oop orig_obj, oop referrer) {
1501 assert(orig_obj != nullptr, "must be");
1502 if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
1503 // This object has injected fields that cannot be supported easily, so we disallow them for now.
1504 // If you get an error here, you probably made a change in the JDK library that has added
1505 // these objects that are referenced (directly or indirectly) by static fields.
1506 ResourceMark rm;
1507 log_error(cds, heap)("Cannot archive object " PTR_FORMAT " of class %s", p2i(orig_obj), orig_obj->klass()->external_name());
1508 debug_trace();
1509 MetaspaceShared::unrecoverable_writing_error();
1510 }
1511
1512 if (log_is_enabled(Debug, cds, heap) && java_lang_Class::is_instance(orig_obj)) {
1513 ResourceMark rm;
1514 LogTarget(Debug, cds, heap) log;
1515 LogStream out(log);
1516 out.print("Found java mirror " PTR_FORMAT " ", p2i(orig_obj));
1517 Klass* k = java_lang_Class::as_Klass(orig_obj);
1518 if (k != nullptr) {
1519 out.print("%s", k->external_name());
1520 } else {
1521 out.print("primitive");
1522 }
1523 out.print_cr("; scratch mirror = " PTR_FORMAT,
1524 p2i(scratch_java_mirror(orig_obj)));
1525 }
1526
1527 if (CDSConfig::is_initing_classes_at_dump_time()) {
1528 if (java_lang_Class::is_instance(orig_obj)) {
1529 orig_obj = scratch_java_mirror(orig_obj);
1530 assert(orig_obj != nullptr, "must be archived");
1531 }
1532 } else if (java_lang_Class::is_instance(orig_obj) && subgraph_info != _dump_time_special_subgraph) {
1533 // Without CDSConfig::is_initing_classes_at_dump_time(), we only allow archived objects to
1534 // point to the mirrors of (1) j.l.Object, (2) primitive classes, and (3) box classes. These are initialized
1535 // very early by HeapShared::init_box_classes().
1536 if (orig_obj == vmClasses::Object_klass()->java_mirror()
1537 || java_lang_Class::is_primitive(orig_obj)
1538 || orig_obj == vmClasses::Boolean_klass()->java_mirror()
1539 || orig_obj == vmClasses::Character_klass()->java_mirror()
1540 || orig_obj == vmClasses::Float_klass()->java_mirror()
1541 || orig_obj == vmClasses::Double_klass()->java_mirror()
1542 || orig_obj == vmClasses::Byte_klass()->java_mirror()
1543 || orig_obj == vmClasses::Short_klass()->java_mirror()
1544 || orig_obj == vmClasses::Integer_klass()->java_mirror()
1545 || orig_obj == vmClasses::Long_klass()->java_mirror()
1546 || orig_obj == vmClasses::Void_klass()->java_mirror()) {
1547 orig_obj = scratch_java_mirror(orig_obj);
1548 assert(orig_obj != nullptr, "must be archived");
1549 } else {
1550 // If you get an error here, you probably made a change in the JDK library that has added a Class
1551 // object that is referenced (directly or indirectly) by an ArchivableStaticFieldInfo
1552 // defined at the top of this file.
1553 log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
1554 debug_trace();
1555 MetaspaceShared::unrecoverable_writing_error();
1556 }
1557 }
1558
1559 if (has_been_seen_during_subgraph_recording(orig_obj)) {
1560 // orig_obj has already been archived and traced. Nothing more to do.
1561 return true;
1562 } else {
1563 set_has_been_seen_during_subgraph_recording(orig_obj);
1564 }
1565
1566 bool already_archived = has_been_archived(orig_obj);
1567 bool record_klasses_only = already_archived;
1568 if (!already_archived) {
1569 ++_num_new_archived_objs;
1570 if (!archive_object(orig_obj, referrer, subgraph_info)) {
1571 // Skip archiving the sub-graph referenced from the current entry field.
1572 ResourceMark rm;
1573 log_error(cds, heap)(
1574 "Cannot archive the sub-graph referenced from %s object ("
1575 PTR_FORMAT ") size %zu, skipped.",
1576 orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
1577 if (level == 1) {
1578 // Don't archive a subgraph root that's too big. For archives static fields, that's OK
1579 // as the Java code will take care of initializing this field dynamically.
1580 return false;
1581 } else {
1582 // We don't know how to handle an object that has been archived, but some of its reachable
1583 // objects cannot be archived. Bail out for now. We might need to fix this in the future if
1584 // we have a real use case.
1585 MetaspaceShared::unrecoverable_writing_error();
1586 }
1587 }
1588 }
1589
1590 Klass *orig_k = orig_obj->klass();
1591 subgraph_info->add_subgraph_object_klass(orig_k);
1592
1593 {
1594 // Find all the oops that are referenced by orig_obj, push them onto the stack
1595 // so we can work on them next.
1596 ResourceMark rm;
1597 OopFieldPusher pusher(stack, level, record_klasses_only, subgraph_info, orig_obj);
1598 orig_obj->oop_iterate(&pusher);
1599 }
1600
1601 if (CDSConfig::is_initing_classes_at_dump_time()) {
1602 // The enum klasses are archived with aot-initialized mirror.
1603 // See AOTClassInitializer::can_archive_initialized_mirror().
1604 } else {
1605 if (CDSEnumKlass::is_enum_obj(orig_obj)) {
1606 CDSEnumKlass::handle_enum_obj(level + 1, subgraph_info, orig_obj);
1607 }
1608 }
1609
1610 return true;
1611 }
1612
1613 //
1614 // Start from the given static field in a java mirror and archive the
1615 // complete sub-graph of java heap objects that are reached directly
1616 // or indirectly from the starting object by following references.
1617 // Sub-graph archiving restrictions (current):
1618 //
1619 // - All classes of objects in the archived sub-graph (including the
1620 // entry class) must be boot class only.
1621 // - No java.lang.Class instance (java mirror) can be included inside
1622 // an archived sub-graph. Mirror can only be the sub-graph entry object.
1623 //
1624 // The Java heap object sub-graph archiving process (see OopFieldPusher):
1625 //
1626 // 1) Java object sub-graph archiving starts from a given static field
1627 // within a Class instance (java mirror). If the static field is a
1628 // reference field and points to a non-null java object, proceed to
1629 // the next step.
1630 //
1631 // 2) Archives the referenced java object. If an archived copy of the
1632 // current object already exists, updates the pointer in the archived
1633 // copy of the referencing object to point to the current archived object.
1634 // Otherwise, proceed to the next step.
1635 //
1636 // 3) Follows all references within the current java object and recursively
1637 // archive the sub-graph of objects starting from each reference.
1638 //
1639 // 4) Updates the pointer in the archived copy of referencing object to
1640 // point to the current archived object.
1641 //
1642 // 5) The Klass of the current java object is added to the list of Klasses
1643 // for loading and initializing before any object in the archived graph can
1644 // be accessed at runtime.
1645 //
1646 void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
1647 const char* klass_name,
1648 int field_offset,
1649 const char* field_name) {
1650 assert(CDSConfig::is_dumping_heap(), "dump time only");
1651 assert(k->is_shared_boot_class(), "must be boot class");
1652
1653 oop m = k->java_mirror();
1654
1655 KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
1656 oop f = m->obj_field(field_offset);
1657
1658 log_debug(cds, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
1659
1660 if (!CompressedOops::is_null(f)) {
1661 if (log_is_enabled(Trace, cds, heap)) {
1662 LogTarget(Trace, cds, heap) log;
1663 LogStream out(log);
1664 f->print_on(&out);
1665 }
1666
1667 bool success = archive_reachable_objects_from(1, subgraph_info, f);
1668 if (!success) {
1669 log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
1670 klass_name, field_name);
1671 } else {
1672 // Note: the field value is not preserved in the archived mirror.
1673 // Record the field as a new subGraph entry point. The recorded
1674 // information is restored from the archive at runtime.
1675 subgraph_info->add_subgraph_entry_field(field_offset, f);
1676 log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(f));
1677 }
1678 } else {
1679 // The field contains null, we still need to record the entry point,
1680 // so it can be restored at runtime.
1681 subgraph_info->add_subgraph_entry_field(field_offset, nullptr);
1682 }
1683 }
1684
1685 #ifndef PRODUCT
1686 class VerifySharedOopClosure: public BasicOopIterateClosure {
1687 public:
1688 void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
1689 void do_oop( oop *p) { VerifySharedOopClosure::do_oop_work(p); }
1690
1691 protected:
1692 template <class T> void do_oop_work(T *p) {
1693 oop obj = RawAccess<>::oop_load(p);
1694 if (!CompressedOops::is_null(obj)) {
1695 HeapShared::verify_reachable_objects_from(obj);
1696 }
1697 }
1698 };
1699
1700 void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
1701 assert(CDSConfig::is_dumping_heap(), "dump time only");
1702 assert(k->is_shared_boot_class(), "must be boot class");
1703
1704 oop m = k->java_mirror();
1705 oop f = m->obj_field(field_offset);
1706 if (!CompressedOops::is_null(f)) {
1707 verify_subgraph_from(f);
1708 }
1709 }
1710
1711 void HeapShared::verify_subgraph_from(oop orig_obj) {
1712 if (!has_been_archived(orig_obj)) {
1713 // It's OK for the root of a subgraph to be not archived. See comments in
1714 // archive_reachable_objects_from().
1715 return;
1716 }
1717
1718 // Verify that all objects reachable from orig_obj are archived.
1719 init_seen_objects_table();
1720 verify_reachable_objects_from(orig_obj);
1721 delete_seen_objects_table();
1722 }
1723
1724 void HeapShared::verify_reachable_objects_from(oop obj) {
1725 _num_total_verifications ++;
1726 if (java_lang_Class::is_instance(obj)) {
1727 obj = scratch_java_mirror(obj);
1728 assert(obj != nullptr, "must be");
1729 }
1730 if (!has_been_seen_during_subgraph_recording(obj)) {
1731 set_has_been_seen_during_subgraph_recording(obj);
1732 assert(has_been_archived(obj), "must be");
1733 VerifySharedOopClosure walker;
1734 obj->oop_iterate(&walker);
1735 }
1736 }
1737 #endif
1738
1739 void HeapShared::check_special_subgraph_classes() {
1740 if (CDSConfig::is_initing_classes_at_dump_time()) {
1741 // We can have aot-initialized classes (such as Enums) that can reference objects
1742 // of arbitrary types. Currently, we trust the JEP 483 implementation to only
1743 // aot-initialize classes that are "safe".
1744 //
1745 // TODO: we need an automatic tool that checks the safety of aot-initialized
1746 // classes (when we extend the set of aot-initialized classes beyond JEP 483)
1747 return;
1748 } else {
1749 // In this case, the special subgraph should contain a few specific types
1750 GrowableArray<Klass*>* klasses = _dump_time_special_subgraph->subgraph_object_klasses();
1751 int num = klasses->length();
1752 for (int i = 0; i < num; i++) {
1753 Klass* subgraph_k = klasses->at(i);
1754 Symbol* name = subgraph_k->name();
1755 if (subgraph_k->is_instance_klass() &&
1756 name != vmSymbols::java_lang_Class() &&
1757 name != vmSymbols::java_lang_String() &&
1758 name != vmSymbols::java_lang_ArithmeticException() &&
1759 name != vmSymbols::java_lang_ArrayIndexOutOfBoundsException() &&
1760 name != vmSymbols::java_lang_ArrayStoreException() &&
1761 name != vmSymbols::java_lang_ClassCastException() &&
1762 name != vmSymbols::java_lang_InternalError() &&
1763 name != vmSymbols::java_lang_NullPointerException()) {
1764 ResourceMark rm;
1765 fatal("special subgraph cannot have objects of type %s", subgraph_k->external_name());
1766 }
1767 }
1768 }
1769 }
1770
1771 HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = nullptr;
1772 HeapShared::PendingOop HeapShared::_object_being_archived;
1773 int HeapShared::_num_new_walked_objs;
1774 int HeapShared::_num_new_archived_objs;
1775 int HeapShared::_num_old_recorded_klasses;
1776
1777 int HeapShared::_num_total_subgraph_recordings = 0;
1778 int HeapShared::_num_total_walked_objs = 0;
1779 int HeapShared::_num_total_archived_objs = 0;
1780 int HeapShared::_num_total_recorded_klasses = 0;
1781 int HeapShared::_num_total_verifications = 0;
1782
1783 bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
1784 return _seen_objects_table->get(obj) != nullptr;
1785 }
1786
1787 void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
1788 assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
1789 _seen_objects_table->put_when_absent(obj, true);
1790 _seen_objects_table->maybe_grow();
1791 ++ _num_new_walked_objs;
1792 }
1793
1794 void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
1795 log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
1796 init_subgraph_info(k, is_full_module_graph);
1797 init_seen_objects_table();
1798 _num_new_walked_objs = 0;
1799 _num_new_archived_objs = 0;
1800 _num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
1801 }
1802
1803 void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
1804 int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
1805 _num_old_recorded_klasses;
1806 log_info(cds, heap)("Done recording subgraph(s) for archived fields in %s: "
1807 "walked %d objs, archived %d new objs, recorded %d classes",
1808 class_name, _num_new_walked_objs, _num_new_archived_objs,
1809 num_new_recorded_klasses);
1810
1811 delete_seen_objects_table();
1812
1813 _num_total_subgraph_recordings ++;
1814 _num_total_walked_objs += _num_new_walked_objs;
1815 _num_total_archived_objs += _num_new_archived_objs;
1816 _num_total_recorded_klasses += num_new_recorded_klasses;
1817 }
1818
1819 class ArchivableStaticFieldFinder: public FieldClosure {
1820 InstanceKlass* _ik;
1821 Symbol* _field_name;
1822 bool _found;
1823 int _offset;
1824 public:
1825 ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
1826 _ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
1827
1828 virtual void do_field(fieldDescriptor* fd) {
1829 if (fd->name() == _field_name) {
1830 assert(!_found, "fields can never be overloaded");
1831 if (is_reference_type(fd->field_type())) {
1832 _found = true;
1833 _offset = fd->offset();
1834 }
1835 }
1836 }
1837 bool found() { return _found; }
1838 int offset() { return _offset; }
1839 };
1840
1841 void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
1842 TRAPS) {
1843 for (int i = 0; fields[i].valid(); i++) {
1844 ArchivableStaticFieldInfo* info = &fields[i];
1845 TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
1846 TempNewSymbol field_name = SymbolTable::new_symbol(info->field_name);
1847 ResourceMark rm; // for stringStream::as_string() etc.
1848
1849 #ifndef PRODUCT
1850 bool is_test_class = (ArchiveHeapTestClass != nullptr) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
1851 const char* test_class_name = ArchiveHeapTestClass;
1852 #else
1853 bool is_test_class = false;
1854 const char* test_class_name = ""; // avoid C++ printf checks warnings.
1855 #endif
1856
1857 if (is_test_class) {
1858 log_warning(cds)("Loading ArchiveHeapTestClass %s ...", test_class_name);
1859 }
1860
1861 Klass* k = SystemDictionary::resolve_or_fail(klass_name, true, THREAD);
1862 if (HAS_PENDING_EXCEPTION) {
1863 CLEAR_PENDING_EXCEPTION;
1864 stringStream st;
1865 st.print("Fail to initialize archive heap: %s cannot be loaded by the boot loader", info->klass_name);
1866 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1867 }
1868
1869 if (!k->is_instance_klass()) {
1870 stringStream st;
1871 st.print("Fail to initialize archive heap: %s is not an instance class", info->klass_name);
1872 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1873 }
1874
1875 InstanceKlass* ik = InstanceKlass::cast(k);
1876 assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
1877 "Only support boot classes");
1878
1879 if (is_test_class) {
1880 if (ik->module()->is_named()) {
1881 // We don't want ArchiveHeapTestClass to be abused to easily load/initialize arbitrary
1882 // core-lib classes. You need to at least append to the bootclasspath.
1883 stringStream st;
1884 st.print("ArchiveHeapTestClass %s is not in unnamed module", test_class_name);
1885 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1886 }
1887
1888 if (ik->package() != nullptr) {
1889 // This restriction makes HeapShared::is_a_test_class_in_unnamed_module() easy.
1890 stringStream st;
1891 st.print("ArchiveHeapTestClass %s is not in unnamed package", test_class_name);
1892 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1893 }
1894 } else {
1895 if (ik->module()->name() != vmSymbols::java_base()) {
1896 // We don't want to deal with cases when a module is unavailable at runtime.
1897 // FUTURE -- load from archived heap only when module graph has not changed
1898 // between dump and runtime.
1899 stringStream st;
1900 st.print("%s is not in java.base module", info->klass_name);
1901 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1902 }
1903 }
1904
1905 if (is_test_class) {
1906 log_warning(cds)("Initializing ArchiveHeapTestClass %s ...", test_class_name);
1907 }
1908 ik->initialize(CHECK);
1909
1910 ArchivableStaticFieldFinder finder(ik, field_name);
1911 ik->do_local_static_fields(&finder);
1912 if (!finder.found()) {
1913 stringStream st;
1914 st.print("Unable to find the static T_OBJECT field %s::%s", info->klass_name, info->field_name);
1915 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
1916 }
1917
1918 info->klass = ik;
1919 info->offset = finder.offset();
1920 }
1921 }
1922
1923 void HeapShared::init_subgraph_entry_fields(TRAPS) {
1924 assert(CDSConfig::is_dumping_heap(), "must be");
1925 _dump_time_subgraph_info_table = new (mtClass)DumpTimeKlassSubGraphInfoTable();
1926 init_subgraph_entry_fields(archive_subgraph_entry_fields, CHECK);
1927 if (CDSConfig::is_dumping_full_module_graph()) {
1928 init_subgraph_entry_fields(fmg_archive_subgraph_entry_fields, CHECK);
1929 }
1930 }
1931
1932 #ifndef PRODUCT
1933 void HeapShared::setup_test_class(const char* test_class_name) {
1934 ArchivableStaticFieldInfo* p = archive_subgraph_entry_fields;
1935 int num_slots = sizeof(archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
1936 assert(p[num_slots - 2].klass_name == nullptr, "must have empty slot that's patched below");
1937 assert(p[num_slots - 1].klass_name == nullptr, "must have empty slot that marks the end of the list");
1938
1939 if (test_class_name != nullptr) {
1940 p[num_slots - 2].klass_name = test_class_name;
1941 p[num_slots - 2].field_name = ARCHIVE_TEST_FIELD_NAME;
1942 }
1943 }
1944
1945 // See if ik is one of the test classes that are pulled in by -XX:ArchiveHeapTestClass
1946 // during runtime. This may be called before the module system is initialized so
1947 // we cannot rely on InstanceKlass::module(), etc.
1948 bool HeapShared::is_a_test_class_in_unnamed_module(Klass* ik) {
1949 if (_test_class != nullptr) {
1950 if (ik == _test_class) {
1951 return true;
1952 }
1953 Array<Klass*>* klasses = _test_class_record->subgraph_object_klasses();
1954 if (klasses == nullptr) {
1955 return false;
1956 }
1957
1958 for (int i = 0; i < klasses->length(); i++) {
1959 Klass* k = klasses->at(i);
1960 if (k == ik) {
1961 Symbol* name;
1962 if (k->is_instance_klass()) {
1963 name = InstanceKlass::cast(k)->name();
1964 } else if (k->is_objArray_klass()) {
1965 Klass* bk = ObjArrayKlass::cast(k)->bottom_klass();
1966 if (!bk->is_instance_klass()) {
1967 return false;
1968 }
1969 name = bk->name();
1970 } else {
1971 return false;
1972 }
1973
1974 // See KlassSubGraphInfo::check_allowed_klass() - we only allow test classes
1975 // to be:
1976 // (A) java.base classes (which must not be in the unnamed module)
1977 // (B) test classes which must be in the unnamed package of the unnamed module.
1978 // So if we see a '/' character in the class name, it must be in (A);
1979 // otherwise it must be in (B).
1980 if (name->index_of_at(0, "/", 1) >= 0) {
1981 return false; // (A)
1982 }
1983
1984 return true; // (B)
1985 }
1986 }
1987 }
1988
1989 return false;
1990 }
1991
1992 void HeapShared::initialize_test_class_from_archive(JavaThread* current) {
1993 Klass* k = _test_class;
1994 if (k != nullptr && ArchiveHeapLoader::is_in_use()) {
1995 JavaThread* THREAD = current;
1996 ExceptionMark em(THREAD);
1997 const ArchivedKlassSubGraphInfoRecord* record =
1998 resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
1999
2000 // The _test_class is in the unnamed module, so it can't call CDS.initializeFromArchive()
2001 // from its <clinit> method. So we set up its "archivedObjects" field first, before
2002 // calling its <clinit>. This is not strictly clean, but it's a convenient way to write unit
2003 // test cases (see test/hotspot/jtreg/runtime/cds/appcds/cacheObject/ArchiveHeapTestClass.java).
2004 if (record != nullptr) {
2005 init_archived_fields_for(k, record);
2006 }
2007 resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
2008 }
2009 }
2010 #endif
2011
2012 void HeapShared::init_for_dumping(TRAPS) {
2013 if (CDSConfig::is_dumping_heap()) {
2014 setup_test_class(ArchiveHeapTestClass);
2015 _dumped_interned_strings = new (mtClass)DumpedInternedStrings(INITIAL_TABLE_SIZE, MAX_TABLE_SIZE);
2016 init_subgraph_entry_fields(CHECK);
2017 }
2018 }
2019
2020 void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
2021 bool is_full_module_graph) {
2022 _num_total_subgraph_recordings = 0;
2023 _num_total_walked_objs = 0;
2024 _num_total_archived_objs = 0;
2025 _num_total_recorded_klasses = 0;
2026 _num_total_verifications = 0;
2027
2028 // For each class X that has one or more archived fields:
2029 // [1] Dump the subgraph of each archived field
2030 // [2] Create a list of all the class of the objects that can be reached
2031 // by any of these static fields.
2032 // At runtime, these classes are initialized before X's archived fields
2033 // are restored by HeapShared::initialize_from_archived_subgraph().
2034 for (int i = 0; fields[i].valid(); ) {
2035 ArchivableStaticFieldInfo* info = &fields[i];
2036 const char* klass_name = info->klass_name;
2037 start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
2038
2039 // If you have specified consecutive fields of the same klass in
2040 // fields[], these will be archived in the same
2041 // {start_recording_subgraph ... done_recording_subgraph} pass to
2042 // save time.
2043 for (; fields[i].valid(); i++) {
2044 ArchivableStaticFieldInfo* f = &fields[i];
2045 if (f->klass_name != klass_name) {
2046 break;
2047 }
2048
2049 archive_reachable_objects_from_static_field(f->klass, f->klass_name,
2050 f->offset, f->field_name);
2051 }
2052 done_recording_subgraph(info->klass, klass_name);
2053 }
2054
2055 log_info(cds, heap)("Archived subgraph records = %d",
2056 _num_total_subgraph_recordings);
2057 log_info(cds, heap)(" Walked %d objects", _num_total_walked_objs);
2058 log_info(cds, heap)(" Archived %d objects", _num_total_archived_objs);
2059 log_info(cds, heap)(" Recorded %d klasses", _num_total_recorded_klasses);
2060
2061 #ifndef PRODUCT
2062 for (int i = 0; fields[i].valid(); i++) {
2063 ArchivableStaticFieldInfo* f = &fields[i];
2064 verify_subgraph_from_static_field(f->klass, f->offset);
2065 }
2066 log_info(cds, heap)(" Verified %d references", _num_total_verifications);
2067 #endif
2068 }
2069
2070 // Not all the strings in the global StringTable are dumped into the archive, because
2071 // some of those strings may be only referenced by classes that are excluded from
2072 // the archive. We need to explicitly mark the strings that are:
2073 // [1] used by classes that WILL be archived;
2074 // [2] included in the SharedArchiveConfigFile.
2075 void HeapShared::add_to_dumped_interned_strings(oop string) {
2076 assert_at_safepoint(); // DumpedInternedStrings uses raw oops
2077 assert(!ArchiveHeapWriter::is_string_too_large_to_archive(string), "must be");
2078 bool created;
2079 _dumped_interned_strings->put_if_absent(string, true, &created);
2080 if (created) {
2081 // Prevent string deduplication from changing the value field to
2082 // something not in the archive.
2083 java_lang_String::set_deduplication_forbidden(string);
2084 _dumped_interned_strings->maybe_grow();
2085 }
2086 }
2087
2088 bool HeapShared::is_dumped_interned_string(oop o) {
2089 return _dumped_interned_strings->get(o) != nullptr;
2090 }
2091
2092 void HeapShared::debug_trace() {
2093 ResourceMark rm;
2094 oop referrer = _object_being_archived.referrer();
2095 if (referrer != nullptr) {
2096 LogStream ls(Log(cds, heap)::error());
2097 ls.print_cr("Reference trace");
2098 CDSHeapVerifier::trace_to_root(&ls, referrer);
2099 }
2100 }
2101
2102 #ifndef PRODUCT
2103 // At dump-time, find the location of all the non-null oop pointers in an archived heap
2104 // region. This way we can quickly relocate all the pointers without using
2105 // BasicOopIterateClosure at runtime.
2106 class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
2107 void* _start;
2108 BitMap *_oopmap;
2109 int _num_total_oops;
2110 int _num_null_oops;
2111 public:
2112 FindEmbeddedNonNullPointers(void* start, BitMap* oopmap)
2113 : _start(start), _oopmap(oopmap), _num_total_oops(0), _num_null_oops(0) {}
2114
2115 virtual void do_oop(narrowOop* p) {
2116 assert(UseCompressedOops, "sanity");
2117 _num_total_oops ++;
2118 narrowOop v = *p;
2119 if (!CompressedOops::is_null(v)) {
2120 size_t idx = p - (narrowOop*)_start;
2121 _oopmap->set_bit(idx);
2122 } else {
2123 _num_null_oops ++;
2124 }
2125 }
2126 virtual void do_oop(oop* p) {
2127 assert(!UseCompressedOops, "sanity");
2128 _num_total_oops ++;
2129 if ((*p) != nullptr) {
2130 size_t idx = p - (oop*)_start;
2131 _oopmap->set_bit(idx);
2132 } else {
2133 _num_null_oops ++;
2134 }
2135 }
2136 int num_total_oops() const { return _num_total_oops; }
2137 int num_null_oops() const { return _num_null_oops; }
2138 };
2139 #endif
2140
2141 void HeapShared::count_allocation(size_t size) {
2142 _total_obj_count ++;
2143 _total_obj_size += size;
2144 for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
2145 if (size <= (size_t(1) << i)) {
2146 _alloc_count[i] ++;
2147 _alloc_size[i] += size;
2148 return;
2149 }
2150 }
2151 }
2152
2153 static double avg_size(size_t size, size_t count) {
2154 double avg = 0;
2155 if (count > 0) {
2156 avg = double(size * HeapWordSize) / double(count);
2157 }
2158 return avg;
2159 }
2160
2161 void HeapShared::print_stats() {
2162 size_t huge_count = _total_obj_count;
2163 size_t huge_size = _total_obj_size;
2164
2165 for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
2166 size_t byte_size_limit = (size_t(1) << i) * HeapWordSize;
2167 size_t count = _alloc_count[i];
2168 size_t size = _alloc_size[i];
2169 log_info(cds, heap)("%8zu objects are <= %-6zu"
2170 " bytes (total %8zu bytes, avg %8.1f bytes)",
2171 count, byte_size_limit, size * HeapWordSize, avg_size(size, count));
2172 huge_count -= count;
2173 huge_size -= size;
2174 }
2175
2176 log_info(cds, heap)("%8zu huge objects (total %8zu bytes"
2177 ", avg %8.1f bytes)",
2178 huge_count, huge_size * HeapWordSize,
2179 avg_size(huge_size, huge_count));
2180 log_info(cds, heap)("%8zu total objects (total %8zu bytes"
2181 ", avg %8.1f bytes)",
2182 _total_obj_count, _total_obj_size * HeapWordSize,
2183 avg_size(_total_obj_size, _total_obj_count));
2184 }
2185
2186 bool HeapShared::is_archived_boot_layer_available(JavaThread* current) {
2187 TempNewSymbol klass_name = SymbolTable::new_symbol(ARCHIVED_BOOT_LAYER_CLASS);
2188 InstanceKlass* k = SystemDictionary::find_instance_klass(current, klass_name, Handle());
2189 if (k == nullptr) {
2190 return false;
2191 } else {
2192 TempNewSymbol field_name = SymbolTable::new_symbol(ARCHIVED_BOOT_LAYER_FIELD);
2193 TempNewSymbol field_signature = SymbolTable::new_symbol("Ljdk/internal/module/ArchivedBootLayer;");
2194 fieldDescriptor fd;
2195 if (k->find_field(field_name, field_signature, true, &fd) != nullptr) {
2196 oop m = k->java_mirror();
2197 oop f = m->obj_field(fd.offset());
2198 if (CompressedOops::is_null(f)) {
2199 return false;
2200 }
2201 } else {
2202 return false;
2203 }
2204 }
2205 return true;
2206 }
2207
2208 #endif // INCLUDE_CDS_JAVA_HEAP