1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/archiveHeapLoader.hpp"
27 #include "cds/cdsConfig.hpp"
28 #include "cds/heapShared.hpp"
29 #include "classfile/classLoader.hpp"
30 #include "classfile/classLoaderData.inline.hpp"
31 #include "classfile/classLoaderDataGraph.inline.hpp"
32 #include "classfile/javaClasses.inline.hpp"
33 #include "classfile/moduleEntry.hpp"
34 #include "classfile/systemDictionary.hpp"
35 #include "classfile/systemDictionaryShared.hpp"
36 #include "classfile/vmClasses.hpp"
37 #include "classfile/vmSymbols.hpp"
38 #include "gc/shared/collectedHeap.inline.hpp"
39 #include "jvm_io.h"
40 #include "logging/log.hpp"
41 #include "memory/metadataFactory.hpp"
42 #include "memory/metaspaceClosure.hpp"
43 #include "memory/oopFactory.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "memory/universe.hpp"
46 #include "oops/compressedOops.inline.hpp"
47 #include "oops/instanceKlass.hpp"
48 #include "oops/klass.inline.hpp"
49 #include "oops/objArrayKlass.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/oopHandle.inline.hpp"
52 #include "prims/jvmtiExport.hpp"
53 #include "runtime/atomic.hpp"
54 #include "runtime/handles.inline.hpp"
55 #include "runtime/perfData.hpp"
56 #include "utilities/macros.hpp"
57 #include "utilities/powerOfTwo.hpp"
58 #include "utilities/rotate_bits.hpp"
59 #include "utilities/stack.inline.hpp"
60
61 void Klass::set_java_mirror(Handle m) {
62 assert(!m.is_null(), "New mirror should never be null.");
63 assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
64 _java_mirror = class_loader_data()->add_handle(m);
65 }
66
67 bool Klass::is_cloneable() const {
68 return _access_flags.is_cloneable_fast() ||
69 is_subtype_of(vmClasses::Cloneable_klass());
70 }
71
72 void Klass::set_is_cloneable() {
73 if (name() == vmSymbols::java_lang_invoke_MemberName()) {
74 assert(is_final(), "no subclasses allowed");
75 // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
76 } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
77 // Reference cloning should not be intrinsified and always happen in JVM_Clone.
78 } else {
79 _access_flags.set_is_cloneable_fast();
80 }
81 }
82
83 uint8_t Klass::compute_hash_slot(Symbol* n) {
84 uint hash_code;
85 // Special cases for the two superclasses of all Array instances.
86 // Code elsewhere assumes, for all instances of ArrayKlass, that
87 // these two interfaces will be in this order.
88
89 // We ensure there are some empty slots in the hash table between
90 // these two very common interfaces because if they were adjacent
91 // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1
92 // would result in a probe length of 3.
93 if (n == vmSymbols::java_lang_Cloneable()) {
94 hash_code = 0;
95 } else if (n == vmSymbols::java_io_Serializable()) {
96 hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2;
97 } else {
98 auto s = (const jbyte*) n->bytes();
99 hash_code = java_lang_String::hash_code(s, n->utf8_length());
100 // We use String::hash_code here (rather than e.g.
101 // Symbol::identity_hash()) in order to have a hash code that
102 // does not change from run to run. We want that because the
103 // hash value for a secondary superclass appears in generated
104 // code as a constant.
105
106 // This constant is magic: see Knuth, "Fibonacci Hashing".
107 constexpr uint multiplier
108 = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 ))
109 constexpr uint hash_shift = sizeof(hash_code) * 8 - 6;
110 // The leading bits of the least significant half of the product.
111 hash_code = (hash_code * multiplier) >> hash_shift;
112
113 if (StressSecondarySupers) {
114 // Generate many hash collisions in order to stress-test the
115 // linear search fallback.
116 hash_code = hash_code % 3;
117 hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3);
118 }
119 }
120
121 return (hash_code & SECONDARY_SUPERS_TABLE_MASK);
122 }
123
124 void Klass::set_name(Symbol* n) {
125 _name = n;
126
127 if (_name != nullptr) {
128 _name->increment_refcount();
129 }
130
131 if (UseSecondarySupersTable) {
132 elapsedTimer selftime;
133 selftime.start();
134
135 _hash_slot = compute_hash_slot(n);
136 assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required");
137
138 selftime.stop();
139 if (UsePerfData) {
140 ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks());
141 }
142 }
143
144 if (CDSConfig::is_dumping_archive() && is_instance_klass()) {
145 SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
146 }
147 }
148
149 bool Klass::is_subclass_of(const Klass* k) const {
150 // Run up the super chain and check
151 if (this == k) return true;
152
153 Klass* t = const_cast<Klass*>(this)->super();
154
155 while (t != nullptr) {
156 if (t == k) return true;
157 t = t->super();
158 }
159 return false;
160 }
161
162 void Klass::release_C_heap_structures(bool release_constant_pool) {
163 if (_name != nullptr) _name->decrement_refcount();
164 }
165
166 bool Klass::search_secondary_supers(Klass* k) const {
167 // Put some extra logic here out-of-line, before the search proper.
168 // This cuts down the size of the inline method.
169
170 // This is necessary, since I am never in my own secondary_super list.
171 if (this == k)
172 return true;
173 // Scan the array-of-objects for a match
174 int cnt = secondary_supers()->length();
175 for (int i = 0; i < cnt; i++) {
176 if (secondary_supers()->at(i) == k) {
177 ((Klass*)this)->set_secondary_super_cache(k);
178 return true;
179 }
180 }
181 return false;
182 }
183
184 // Return self, except for abstract classes with exactly 1
185 // implementor. Then return the 1 concrete implementation.
186 Klass *Klass::up_cast_abstract() {
187 Klass *r = this;
188 while( r->is_abstract() ) { // Receiver is abstract?
189 Klass *s = r->subklass(); // Check for exactly 1 subklass
190 if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up
191 return this; // Return 'this' as a no-progress flag
192 r = s; // Loop till find concrete class
193 }
194 return r; // Return the 1 concrete class
195 }
196
197 // Find LCA in class hierarchy
198 Klass *Klass::LCA( Klass *k2 ) {
199 Klass *k1 = this;
200 while( 1 ) {
201 if( k1->is_subtype_of(k2) ) return k2;
202 if( k2->is_subtype_of(k1) ) return k1;
203 k1 = k1->super();
204 k2 = k2->super();
205 }
206 }
207
208
209 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
210 ResourceMark rm(THREAD);
211 THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
212 : vmSymbols::java_lang_InstantiationException(), external_name());
213 }
214
215
216 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
217 ResourceMark rm(THREAD);
218 assert(s != nullptr, "Throw NPE!");
219 THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
220 err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
221 }
222
223
224 void Klass::initialize(TRAPS) {
225 ShouldNotReachHere();
226 }
227
228 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
229 #ifdef ASSERT
230 tty->print_cr("Error: find_field called on a klass oop."
231 " Likely error: reflection method does not correctly"
232 " wrap return value in a mirror object.");
233 #endif
234 ShouldNotReachHere();
235 return nullptr;
236 }
237
238 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
239 OverpassLookupMode overpass_mode,
240 PrivateLookupMode private_mode) const {
241 #ifdef ASSERT
242 tty->print_cr("Error: uncached_lookup_method called on a klass oop."
243 " Likely error: reflection method does not correctly"
244 " wrap return value in a mirror object.");
245 #endif
246 ShouldNotReachHere();
247 return nullptr;
248 }
249
250 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
251 return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
252 }
253
254 Klass::Klass() : _kind(UnknownKlassKind) {
255 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
256 }
257
258 // "Normal" instantiation is preceded by a MetaspaceObj allocation
259 // which zeros out memory - calloc equivalent.
260 // The constructor is also used from CppVtableCloner,
261 // which doesn't zero out the memory before calling the constructor.
262 Klass::Klass(KlassKind kind) : _kind(kind),
263 _shared_class_path_index(-1) {
264 CDS_ONLY(_shared_class_flags = 0;)
265 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
266 _primary_supers[0] = this;
267 set_super_check_offset(in_bytes(primary_supers_offset()));
268 }
269
270 jint Klass::array_layout_helper(BasicType etype) {
271 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
272 // Note that T_ARRAY is not allowed here.
273 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
274 int esize = type2aelembytes(etype);
275 bool isobj = (etype == T_OBJECT);
276 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
277 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
278
279 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
280 assert(layout_helper_is_array(lh), "correct kind");
281 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
282 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
283 assert(layout_helper_header_size(lh) == hsize, "correct decode");
284 assert(layout_helper_element_type(lh) == etype, "correct decode");
285 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
286
287 return lh;
288 }
289
290 bool Klass::can_be_primary_super_slow() const {
291 if (super() == nullptr)
292 return true;
293 else if (super()->super_depth() >= primary_super_limit()-1)
294 return false;
295 else
296 return true;
297 }
298
299 void Klass::set_secondary_supers(Array<Klass*>* secondaries) {
300 assert(!UseSecondarySupersTable || secondaries == nullptr, "");
301 set_secondary_supers(secondaries, SECONDARY_SUPERS_BITMAP_EMPTY);
302 }
303
304 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
305 #ifdef ASSERT
306 if (UseSecondarySupersTable && secondaries != nullptr) {
307 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
308 assert(bitmap == real_bitmap, "must be");
309 }
310 #endif
311 _bitmap = bitmap;
312 _secondary_supers = secondaries;
313
314 if (secondaries != nullptr) {
315 LogMessage(class, load) msg;
316 NonInterleavingLogStream log {LogLevel::Debug, msg};
317 if (log.is_enabled()) {
318 ResourceMark rm;
319 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
320 print_secondary_supers_on(&log);
321 }
322 }
323 }
324
325 // Hashed secondary superclasses
326 //
327 // We use a compressed 64-entry hash table with linear probing. We
328 // start by creating a hash table in the usual way, followed by a pass
329 // that removes all the null entries. To indicate which entries would
330 // have been null we use a bitmap that contains a 1 in each position
331 // where an entry is present, 0 otherwise. This bitmap also serves as
332 // a kind of Bloom filter, which in many cases allows us quickly to
333 // eliminate the possibility that something is a member of a set of
334 // secondaries.
335 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
336 const int length = secondaries->length();
337
338 if (length == 0) {
339 return SECONDARY_SUPERS_BITMAP_EMPTY;
340 }
341
342 if (length == 1) {
343 int hash_slot = secondaries->at(0)->hash_slot();
344 return uintx(1) << hash_slot;
345 }
346
347 // For performance reasons we don't use a hashed table unless there
348 // are at least two empty slots in it. If there were only one empty
349 // slot it'd take a long time to create the table and the resulting
350 // search would be no faster than linear probing.
351 if (length > SECONDARY_SUPERS_TABLE_SIZE - 2) {
352 return SECONDARY_SUPERS_BITMAP_FULL;
353 }
354
355 {
356 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time());
357
358 ResourceMark rm;
359 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
360 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
361 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
362
363 for (int j = 0; j < length; j++) {
364 Klass* k = secondaries->at(j);
365 hash_insert(k, hashed_secondaries, bitmap);
366 }
367
368 // Pack the hashed secondaries array by copying it into the
369 // secondaries array, sans nulls, if modification is allowed.
370 // Otherwise, validate the order.
371 int i = 0;
372 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
373 bool has_element = ((bitmap >> slot) & 1) != 0;
374 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
375 if (has_element) {
376 Klass* k = hashed_secondaries->at(slot);
377 if (rewrite) {
378 secondaries->at_put(i, k);
379 } else if (secondaries->at(i) != k) {
380 assert(false, "broken secondary supers hash table");
381 return SECONDARY_SUPERS_BITMAP_FULL;
382 }
383 i++;
384 }
385 }
386 assert(i == secondaries->length(), "mismatch");
387
388 return bitmap;
389 }
390 }
391
392 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
393 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
394
395 int dist = 0;
396 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
397 Klass* existing = secondaries->at(slot);
398 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
399 if (existing == nullptr) { // no conflict
400 secondaries->at_put(slot, klass);
401 bitmap |= uintx(1) << slot;
402 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
403 return;
404 } else {
405 // Use Robin Hood hashing to minimize the worst case search.
406 // Also, every permutation of the insertion sequence produces
407 // the same final Robin Hood hash table, provided that a
408 // consistent tie breaker is used.
409 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
410 if (existing_dist < dist
411 // This tie breaker ensures that the hash order is maintained.
412 || ((existing_dist == dist)
413 && (uintptr_t(existing) < uintptr_t(klass)))) {
414 Klass* tmp = secondaries->at(slot);
415 secondaries->at_put(slot, klass);
416 klass = tmp;
417 dist = existing_dist;
418 }
419 ++dist;
420 }
421 }
422 }
423
424 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
425 GrowableArray<Klass*>* primaries,
426 GrowableArray<Klass*>* secondaries,
427 uintx& bitmap, TRAPS) {
428 int new_length = primaries->length() + secondaries->length();
429 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
430
431 // Combine the two arrays into a metadata object to pack the array.
432 // The primaries are added in the reverse order, then the secondaries.
433 int fill_p = primaries->length();
434 for (int j = 0; j < fill_p; j++) {
435 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
436 }
437 for( int j = 0; j < secondaries->length(); j++ ) {
438 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
439 }
440 #ifdef ASSERT
441 // We must not copy any null placeholders left over from bootstrap.
442 for (int j = 0; j < secondary_supers->length(); j++) {
443 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
444 }
445 #endif
446
447 if (UseSecondarySupersTable) {
448 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
449 } else {
450 bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
451 }
452 return secondary_supers;
453 }
454
455 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
456 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
457 }
458
459 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
460 uint8_t hash = k->hash_slot();
461 if (hash > 0) {
462 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
463 }
464 return 0;
465 }
466
467
468 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
469 if (k == nullptr) {
470 set_super(nullptr);
471 _primary_supers[0] = this;
472 assert(super_depth() == 0, "Object must already be initialized properly");
473 } else if (k != super() || k == vmClasses::Object_klass()) {
474 assert(super() == nullptr || super() == vmClasses::Object_klass(),
475 "initialize this only once to a non-trivial value");
476 set_super(k);
477 Klass* sup = k;
478 int sup_depth = sup->super_depth();
479 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
480 if (!can_be_primary_super_slow())
481 my_depth = primary_super_limit();
482 for (juint i = 0; i < my_depth; i++) {
483 _primary_supers[i] = sup->_primary_supers[i];
484 }
485 Klass* *super_check_cell;
486 if (my_depth < primary_super_limit()) {
487 _primary_supers[my_depth] = this;
488 super_check_cell = &_primary_supers[my_depth];
489 } else {
490 // Overflow of the primary_supers array forces me to be secondary.
491 super_check_cell = &_secondary_super_cache;
492 }
493 set_super_check_offset(u4((address)super_check_cell - (address) this));
494
495 #ifdef ASSERT
496 {
497 juint j = super_depth();
498 assert(j == my_depth, "computed accessor gets right answer");
499 Klass* t = this;
500 while (!t->can_be_primary_super()) {
501 t = t->super();
502 j = t->super_depth();
503 }
504 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
505 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
506 }
507 while (t != nullptr) {
508 assert(primary_super_of_depth(j) == t, "super list initialization");
509 t = t->super();
510 --j;
511 }
512 assert(j == (juint)-1, "correct depth count");
513 }
514 #endif
515 }
516
517 if (secondary_supers() == nullptr) {
518
519 // Now compute the list of secondary supertypes.
520 // Secondaries can occasionally be on the super chain,
521 // if the inline "_primary_supers" array overflows.
522 int extras = 0;
523 Klass* p;
524 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
525 ++extras;
526 }
527
528 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
529
530 // Compute the "real" non-extra secondaries.
531 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
532 if (secondaries == nullptr) {
533 // secondary_supers set by compute_secondary_supers
534 return;
535 }
536
537 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
538
539 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
540 int i; // Scan for overflow primaries being duplicates of 2nd'arys
541
542 // This happens frequently for very deeply nested arrays: the
543 // primary superclass chain overflows into the secondary. The
544 // secondary list contains the element_klass's secondaries with
545 // an extra array dimension added. If the element_klass's
546 // secondary list already contains some primary overflows, they
547 // (with the extra level of array-ness) will collide with the
548 // normal primary superclass overflows.
549 for( i = 0; i < secondaries->length(); i++ ) {
550 if( secondaries->at(i) == p )
551 break;
552 }
553 if( i < secondaries->length() )
554 continue; // It's a dup, don't put it in
555 primaries->push(p);
556 }
557 // Combine the two arrays into a metadata object to pack the array.
558 uintx bitmap = 0;
559 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
560 set_secondary_supers(s2, bitmap);
561 }
562 }
563
564 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
565 Array<InstanceKlass*>* transitive_interfaces) {
566 assert(num_extra_slots == 0, "override for complex klasses");
567 assert(transitive_interfaces == nullptr, "sanity");
568 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
569 return nullptr;
570 }
571
572
573 // superklass links
574 InstanceKlass* Klass::superklass() const {
575 assert(super() == nullptr || super()->is_instance_klass(), "must be instance klass");
576 return _super == nullptr ? nullptr : InstanceKlass::cast(_super);
577 }
578
579 // subklass links. Used by the compiler (and vtable initialization)
580 // May be cleaned concurrently, so must use the Compile_lock.
581 // The log parameter is for clean_weak_klass_links to report unlinked classes.
582 Klass* Klass::subklass(bool log) const {
583 // Need load_acquire on the _subklass, because it races with inserts that
584 // publishes freshly initialized data.
585 for (Klass* chain = Atomic::load_acquire(&_subklass);
586 chain != nullptr;
587 // Do not need load_acquire on _next_sibling, because inserts never
588 // create _next_sibling edges to dead data.
589 chain = Atomic::load(&chain->_next_sibling))
590 {
591 if (chain->is_loader_alive()) {
592 return chain;
593 } else if (log) {
594 if (log_is_enabled(Trace, class, unload)) {
595 ResourceMark rm;
596 log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
597 }
598 }
599 }
600 return nullptr;
601 }
602
603 Klass* Klass::next_sibling(bool log) const {
604 // Do not need load_acquire on _next_sibling, because inserts never
605 // create _next_sibling edges to dead data.
606 for (Klass* chain = Atomic::load(&_next_sibling);
607 chain != nullptr;
608 chain = Atomic::load(&chain->_next_sibling)) {
609 // Only return alive klass, there may be stale klass
610 // in this chain if cleaned concurrently.
611 if (chain->is_loader_alive()) {
612 return chain;
613 } else if (log) {
614 if (log_is_enabled(Trace, class, unload)) {
615 ResourceMark rm;
616 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
617 }
618 }
619 }
620 return nullptr;
621 }
622
623 void Klass::set_subklass(Klass* s) {
624 assert(s != this, "sanity check");
625 Atomic::release_store(&_subklass, s);
626 }
627
628 void Klass::set_next_sibling(Klass* s) {
629 assert(s != this, "sanity check");
630 // Does not need release semantics. If used by cleanup, it will link to
631 // already safely published data, and if used by inserts, will be published
632 // safely using cmpxchg.
633 Atomic::store(&_next_sibling, s);
634 }
635
636 void Klass::append_to_sibling_list() {
637 if (Universe::is_fully_initialized()) {
638 assert_locked_or_safepoint(Compile_lock);
639 }
640 debug_only(verify();)
641 // add ourselves to superklass' subklass list
642 InstanceKlass* super = superklass();
643 if (super == nullptr) return; // special case: class Object
644 assert((!super->is_interface() // interfaces cannot be supers
645 && (super->superklass() == nullptr || !is_interface())),
646 "an interface can only be a subklass of Object");
647
648 // Make sure there is no stale subklass head
649 super->clean_subklass();
650
651 for (;;) {
652 Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
653 if (prev_first_subklass != nullptr) {
654 // set our sibling to be the superklass' previous first subklass
655 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
656 set_next_sibling(prev_first_subklass);
657 }
658 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
659 // are ever created to not alive klasses. This is an important invariant of the lock-free
660 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
661 if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
662 return;
663 }
664 }
665 debug_only(verify();)
666 }
667
668 void Klass::clean_subklass() {
669 for (;;) {
670 // Need load_acquire, due to contending with concurrent inserts
671 Klass* subklass = Atomic::load_acquire(&_subklass);
672 if (subklass == nullptr || subklass->is_loader_alive()) {
673 return;
674 }
675 // Try to fix _subklass until it points at something not dead.
676 Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
677 }
678 }
679
680 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
681 if (!ClassUnloading || !unloading_occurred) {
682 return;
683 }
684
685 Klass* root = vmClasses::Object_klass();
686 Stack<Klass*, mtGC> stack;
687
688 stack.push(root);
689 while (!stack.is_empty()) {
690 Klass* current = stack.pop();
691
692 assert(current->is_loader_alive(), "just checking, this should be live");
693
694 // Find and set the first alive subklass
695 Klass* sub = current->subklass(true);
696 current->clean_subklass();
697 if (sub != nullptr) {
698 stack.push(sub);
699 }
700
701 // Find and set the first alive sibling
702 Klass* sibling = current->next_sibling(true);
703 current->set_next_sibling(sibling);
704 if (sibling != nullptr) {
705 stack.push(sibling);
706 }
707
708 // Clean the implementors list and method data.
709 if (clean_alive_klasses && current->is_instance_klass()) {
710 InstanceKlass* ik = InstanceKlass::cast(current);
711 ik->clean_weak_instanceklass_links();
712
713 // JVMTI RedefineClasses creates previous versions that are not in
714 // the class hierarchy, so process them here.
715 while ((ik = ik->previous_versions()) != nullptr) {
716 ik->clean_weak_instanceklass_links();
717 }
718 }
719 }
720 }
721
722 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
723 if (log_is_enabled(Trace, cds)) {
724 ResourceMark rm;
725 log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
726 }
727
728 it->push(&_name);
729 it->push(&_secondary_supers);
730 for (int i = 0; i < _primary_super_limit; i++) {
731 it->push(&_primary_supers[i]);
732 }
733 it->push(&_super);
734 if (!CDSConfig::is_dumping_archive()) {
735 // If dumping archive, these may point to excluded classes. There's no need
736 // to follow these pointers anyway, as they will be set to null in
737 // remove_unshareable_info().
738 it->push((Klass**)&_subklass);
739 it->push((Klass**)&_next_sibling);
740 it->push(&_next_link);
741 }
742
743 vtableEntry* vt = start_of_vtable();
744 for (int i=0; i<vtable_length(); i++) {
745 it->push(vt[i].method_addr());
746 }
747 }
748
749 #if INCLUDE_CDS
750 void Klass::remove_unshareable_info() {
751 assert(CDSConfig::is_dumping_archive(),
752 "only called during CDS dump time");
753 JFR_ONLY(REMOVE_ID(this);)
754 if (log_is_enabled(Trace, cds, unshareable)) {
755 ResourceMark rm;
756 log_trace(cds, unshareable)("remove: %s", external_name());
757 }
758
759 // _secondary_super_cache may be updated by an is_subtype_of() call
760 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
761 // null and let it be repopulated at runtime.
762 set_secondary_super_cache(nullptr);
763
764 set_subklass(nullptr);
765 set_next_sibling(nullptr);
766 set_next_link(nullptr);
767
768 // Null out class_loader_data because we don't share that yet.
769 set_class_loader_data(nullptr);
770 set_is_shared();
771
772 // FIXME: validation in Klass::hash_secondary_supers() may fail for shared klasses.
773 // Even though the bitmaps always match, the canonical order of elements in the table
774 // is not guaranteed to stay the same (see tie breaker during Robin Hood hashing in Klass::hash_insert).
775 //assert(compute_secondary_supers_bitmap(secondary_supers()) == _bitmap, "broken table");
776 }
777
778 void Klass::remove_java_mirror() {
779 assert(CDSConfig::is_dumping_archive(), "sanity");
780 if (log_is_enabled(Trace, cds, unshareable)) {
781 ResourceMark rm;
782 log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
783 }
784 // Just null out the mirror. The class_loader_data() no longer exists.
785 clear_java_mirror_handle();
786 }
787
788 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
789 assert(is_klass(), "ensure C++ vtable is restored");
790 assert(is_shared(), "must be set");
791 JFR_ONLY(RESTORE_ID(this);)
792 if (log_is_enabled(Trace, cds, unshareable)) {
793 ResourceMark rm(THREAD);
794 oop class_loader = loader_data->class_loader();
795 log_trace(cds, unshareable)("restore: %s with class loader: %s", external_name(),
796 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
797 }
798
799 // If an exception happened during CDS restore, some of these fields may already be
800 // set. We leave the class on the CLD list, even if incomplete so that we don't
801 // modify the CLD list outside a safepoint.
802 if (class_loader_data() == nullptr) {
803 set_class_loader_data(loader_data);
804
805 // Add to class loader list first before creating the mirror
806 // (same order as class file parsing)
807 loader_data->add_class(this);
808 }
809
810 Handle loader(THREAD, loader_data->class_loader());
811 ModuleEntry* module_entry = nullptr;
812 Klass* k = this;
813 if (k->is_objArray_klass()) {
814 k = ObjArrayKlass::cast(k)->bottom_klass();
815 }
816 // Obtain klass' module.
817 if (k->is_instance_klass()) {
818 InstanceKlass* ik = (InstanceKlass*) k;
819 module_entry = ik->module();
820 } else {
821 module_entry = ModuleEntryTable::javabase_moduleEntry();
822 }
823 // Obtain java.lang.Module, if available
824 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module() : (oop)nullptr));
825
826 if (this->has_archived_mirror_index()) {
827 ResourceMark rm(THREAD);
828 log_debug(cds, mirror)("%s has raw archived mirror", external_name());
829 if (ArchiveHeapLoader::is_in_use()) {
830 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
831 protection_domain,
832 CHECK);
833 if (present) {
834 return;
835 }
836 }
837
838 // No archived mirror data
839 log_debug(cds, mirror)("No archived mirror data for %s", external_name());
840 clear_java_mirror_handle();
841 this->clear_archived_mirror_index();
842 }
843
844 // Only recreate it if not present. A previous attempt to restore may have
845 // gotten an OOM later but keep the mirror if it was created.
846 if (java_mirror() == nullptr) {
847 ResourceMark rm(THREAD);
848 log_trace(cds, mirror)("Recreate mirror for %s", external_name());
849 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
850 }
851 }
852 #endif // INCLUDE_CDS
853
854 #if INCLUDE_CDS_JAVA_HEAP
855 oop Klass::archived_java_mirror() {
856 assert(has_archived_mirror_index(), "must have archived mirror");
857 return HeapShared::get_root(_archived_mirror_index);
858 }
859
860 void Klass::clear_archived_mirror_index() {
861 if (_archived_mirror_index >= 0) {
862 HeapShared::clear_root(_archived_mirror_index);
863 }
864 _archived_mirror_index = -1;
865 }
866
867 // No GC barrier
868 void Klass::set_archived_java_mirror(int mirror_index) {
869 assert(CDSConfig::is_dumping_heap(), "sanity");
870 _archived_mirror_index = mirror_index;
871 }
872 #endif // INCLUDE_CDS_JAVA_HEAP
873
874 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
875 if (length > max_length) {
876 if (!THREAD->is_in_internal_oome_mark()) {
877 report_java_out_of_memory("Requested array size exceeds VM limit");
878 JvmtiExport::post_array_size_exhausted();
879 THROW_OOP(Universe::out_of_memory_error_array_size());
880 } else {
881 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
882 }
883 } else if (length < 0) {
884 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
885 }
886 }
887
888 // Replace the last '+' char with '/'.
889 static char* convert_hidden_name_to_java(Symbol* name) {
890 size_t name_len = name->utf8_length();
891 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
892 name->as_klass_external_name(result, (int)name_len + 1);
893 for (int index = (int)name_len; index > 0; index--) {
894 if (result[index] == '+') {
895 result[index] = JVM_SIGNATURE_SLASH;
896 break;
897 }
898 }
899 return result;
900 }
901
902 // In product mode, this function doesn't have virtual function calls so
903 // there might be some performance advantage to handling InstanceKlass here.
904 const char* Klass::external_name() const {
905 if (is_instance_klass()) {
906 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
907 if (ik->is_hidden()) {
908 char* result = convert_hidden_name_to_java(name());
909 return result;
910 }
911 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
912 char* result = convert_hidden_name_to_java(name());
913 return result;
914 }
915 if (name() == nullptr) return "<unknown>";
916 return name()->as_klass_external_name();
917 }
918
919 const char* Klass::signature_name() const {
920 if (name() == nullptr) return "<unknown>";
921 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
922 size_t name_len = name()->utf8_length();
923 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
924 name()->as_C_string(result, (int)name_len + 1);
925 for (int index = (int)name_len; index > 0; index--) {
926 if (result[index] == '+') {
927 result[index] = JVM_SIGNATURE_DOT;
928 break;
929 }
930 }
931 return result;
932 }
933 return name()->as_C_string();
934 }
935
936 const char* Klass::external_kind() const {
937 if (is_interface()) return "interface";
938 if (is_abstract()) return "abstract class";
939 return "class";
940 }
941
942 // Unless overridden, jvmti_class_status has no flags set.
943 jint Klass::jvmti_class_status() const {
944 return 0;
945 }
946
947
948 // Printing
949
950 void Klass::print_on(outputStream* st) const {
951 ResourceMark rm;
952 // print title
953 st->print("%s", internal_name());
954 print_address_on(st);
955 st->cr();
956 }
957
958 #define BULLET " - "
959
960 // Caller needs ResourceMark
961 void Klass::oop_print_on(oop obj, outputStream* st) {
962 // print title
963 st->print_cr("%s ", internal_name());
964 obj->print_address_on(st);
965
966 if (WizardMode) {
967 // print header
968 obj->mark().print_on(st);
969 st->cr();
970 }
971
972 // print class
973 st->print(BULLET"klass: ");
974 obj->klass()->print_value_on(st);
975 st->cr();
976 }
977
978 void Klass::oop_print_value_on(oop obj, outputStream* st) {
979 // print title
980 ResourceMark rm; // Cannot print in debug mode without this
981 st->print("%s", internal_name());
982 obj->print_address_on(st);
983 }
984
985 // Verification
986
987 void Klass::verify_on(outputStream* st) {
988
989 // This can be expensive, but it is worth checking that this klass is actually
990 // in the CLD graph but not in production.
991 assert(Metaspace::contains((address)this), "Should be");
992
993 guarantee(this->is_klass(),"should be klass");
994
995 if (super() != nullptr) {
996 guarantee(super()->is_klass(), "should be klass");
997 }
998 if (secondary_super_cache() != nullptr) {
999 Klass* ko = secondary_super_cache();
1000 guarantee(ko->is_klass(), "should be klass");
1001 }
1002 for ( uint i = 0; i < primary_super_limit(); i++ ) {
1003 Klass* ko = _primary_supers[i];
1004 if (ko != nullptr) {
1005 guarantee(ko->is_klass(), "should be klass");
1006 }
1007 }
1008
1009 if (java_mirror_no_keepalive() != nullptr) {
1010 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
1011 }
1012 }
1013
1014 void Klass::oop_verify_on(oop obj, outputStream* st) {
1015 guarantee(oopDesc::is_oop(obj), "should be oop");
1016 guarantee(obj->klass()->is_klass(), "klass field is not a klass");
1017 }
1018
1019 bool Klass::is_valid(Klass* k) {
1020 if (!is_aligned(k, sizeof(MetaWord))) return false;
1021 if ((size_t)k < os::min_page_size()) return false;
1022
1023 if (!os::is_readable_range(k, k + 1)) return false;
1024 if (!Metaspace::contains(k)) return false;
1025
1026 if (!Symbol::is_valid(k->name())) return false;
1027 return ClassLoaderDataGraph::is_valid(k->class_loader_data());
1028 }
1029
1030 Method* Klass::method_at_vtable(int index) {
1031 #ifndef PRODUCT
1032 assert(index >= 0, "valid vtable index");
1033 if (DebugVtables) {
1034 verify_vtable_index(index);
1035 }
1036 #endif
1037 return start_of_vtable()[index].method();
1038 }
1039
1040
1041 #ifndef PRODUCT
1042
1043 bool Klass::verify_vtable_index(int i) {
1044 int limit = vtable_length()/vtableEntry::size();
1045 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
1046 return true;
1047 }
1048
1049 #endif // PRODUCT
1050
1051 // Caller needs ResourceMark
1052 // joint_in_module_of_loader provides an optimization if 2 classes are in
1053 // the same module to succinctly print out relevant information about their
1054 // module name and class loader's name_and_id for error messages.
1055 // Format:
1056 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
1057 // are in module <module-name>[@<version>]
1058 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1059 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
1060 assert(module() == class2->module(), "classes do not have the same module");
1061 const char* class1_name = external_name();
1062 size_t len = strlen(class1_name) + 1;
1063
1064 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
1065 len += strlen(class2_description);
1066
1067 len += strlen(" and ");
1068
1069 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1070
1071 // Just return the FQN if error when allocating string
1072 if (joint_description == nullptr) {
1073 return class1_name;
1074 }
1075
1076 jio_snprintf(joint_description, len, "%s and %s",
1077 class1_name,
1078 class2_description);
1079
1080 return joint_description;
1081 }
1082
1083 // Caller needs ResourceMark
1084 // class_in_module_of_loader provides a standard way to include
1085 // relevant information about a class, such as its module name as
1086 // well as its class loader's name_and_id, in error messages and logging.
1087 // Format:
1088 // <fully-qualified-external-class-name> is in module <module-name>[@<version>]
1089 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1090 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
1091 // 1. fully qualified external name of class
1092 const char* klass_name = external_name();
1093 size_t len = strlen(klass_name) + 1;
1094
1095 // 2. module name + @version
1096 const char* module_name = "";
1097 const char* version = "";
1098 bool has_version = false;
1099 bool module_is_named = false;
1100 const char* module_name_phrase = "";
1101 const Klass* bottom_klass = is_objArray_klass() ?
1102 ObjArrayKlass::cast(this)->bottom_klass() : this;
1103 if (bottom_klass->is_instance_klass()) {
1104 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
1105 if (module->is_named()) {
1106 module_is_named = true;
1107 module_name_phrase = "module ";
1108 module_name = module->name()->as_C_string();
1109 len += strlen(module_name);
1110 // Use version if exists and is not a jdk module
1111 if (module->should_show_version()) {
1112 has_version = true;
1113 version = module->version()->as_C_string();
1114 // Include stlen(version) + 1 for the "@"
1115 len += strlen(version) + 1;
1116 }
1117 } else {
1118 module_name = UNNAMED_MODULE;
1119 len += UNNAMED_MODULE_LEN;
1120 }
1121 } else {
1122 // klass is an array of primitives, module is java.base
1123 module_is_named = true;
1124 module_name_phrase = "module ";
1125 module_name = JAVA_BASE_NAME;
1126 len += JAVA_BASE_NAME_LEN;
1127 }
1128
1129 // 3. class loader's name_and_id
1130 ClassLoaderData* cld = class_loader_data();
1131 assert(cld != nullptr, "class_loader_data should not be null");
1132 const char* loader_name_and_id = cld->loader_name_and_id();
1133 len += strlen(loader_name_and_id);
1134
1135 // 4. include parent loader information
1136 const char* parent_loader_phrase = "";
1137 const char* parent_loader_name_and_id = "";
1138 if (include_parent_loader &&
1139 !cld->is_builtin_class_loader_data()) {
1140 oop parent_loader = java_lang_ClassLoader::parent(class_loader());
1141 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
1142 // The parent loader's ClassLoaderData could be null if it is
1143 // a delegating class loader that has never defined a class.
1144 // In this case the loader's name must be obtained via the parent loader's oop.
1145 if (parent_cld == nullptr) {
1146 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
1147 if (cl_name_and_id != nullptr) {
1148 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
1149 }
1150 } else {
1151 parent_loader_name_and_id = parent_cld->loader_name_and_id();
1152 }
1153 parent_loader_phrase = ", parent loader ";
1154 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
1155 }
1156
1157 // Start to construct final full class description string
1158 len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
1159 len += strlen(module_name_phrase) + strlen(" of loader ");
1160
1161 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1162
1163 // Just return the FQN if error when allocating string
1164 if (class_description == nullptr) {
1165 return klass_name;
1166 }
1167
1168 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
1169 klass_name,
1170 (use_are) ? "are" : "is",
1171 module_name_phrase,
1172 module_name,
1173 (has_version) ? "@" : "",
1174 (has_version) ? version : "",
1175 loader_name_and_id,
1176 parent_loader_phrase,
1177 parent_loader_name_and_id);
1178
1179 return class_description;
1180 }
1181
1182 class LookupStats : StackObj {
1183 private:
1184 uint _no_of_samples;
1185 uint _worst;
1186 uint _worst_count;
1187 uint _average;
1188 uint _best;
1189 uint _best_count;
1190 public:
1191 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {}
1192
1193 ~LookupStats() {
1194 assert(_best <= _worst || _no_of_samples == 0, "sanity");
1195 }
1196
1197 void sample(uint value) {
1198 ++_no_of_samples;
1199 _average += value;
1200
1201 if (_worst < value) {
1202 _worst = value;
1203 _worst_count = 1;
1204 } else if (_worst == value) {
1205 ++_worst_count;
1206 }
1207
1208 if (_best > value) {
1209 _best = value;
1210 _best_count = 1;
1211 } else if (_best == value) {
1212 ++_best_count;
1213 }
1214 }
1215
1216 void print_on(outputStream* st) const {
1217 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples);
1218 if (_best_count < _no_of_samples) {
1219 st->print("; average: %4.1f; worst: %2d (%4.1f%%)",
1220 (1.0 * _average) / _no_of_samples,
1221 _worst, (100.0 * _worst_count) / _no_of_samples);
1222 }
1223 }
1224 };
1225
1226 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) {
1227 int num_of_supers = secondary_supers->length();
1228
1229 LookupStats s;
1230 for (int i = 0; i < num_of_supers; i++) {
1231 Klass* secondary_super = secondary_supers->at(i);
1232 int home_slot = Klass::compute_home_slot(secondary_super, bitmap);
1233 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK);
1234 s.sample(score);
1235 }
1236 st->print("positive_lookup: "); s.print_on(st);
1237 }
1238
1239 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) {
1240 assert(~bitmap != 0, "no zeroes");
1241 uintx start = rotate_right(bitmap, slot);
1242 return count_trailing_zeros(~start);
1243 }
1244
1245 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) {
1246 LookupStats s;
1247 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
1248 uint score = compute_distance_to_nearest_zero(slot, bitmap);
1249 s.sample(score);
1250 }
1251 st->print("negative_lookup: "); s.print_on(st);
1252 }
1253
1254 void Klass::print_secondary_supers_on(outputStream* st) const {
1255 if (secondary_supers() != nullptr) {
1256 if (UseSecondarySupersTable) {
1257 st->print(" - "); st->print("%d elements;", _secondary_supers->length());
1258 st->print_cr(" bitmap: " UINTX_FORMAT_X_0 ";", _bitmap);
1259 if (_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY &&
1260 _bitmap != SECONDARY_SUPERS_BITMAP_FULL) {
1261 st->print(" - "); print_positive_lookup_stats(secondary_supers(), _bitmap, st); st->cr();
1262 st->print(" - "); print_negative_lookup_stats(_bitmap, st); st->cr();
1263 }
1264 }
1265 } else {
1266 st->print("null");
1267 }
1268 }
1269
1270 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) {
1271 ResourceMark rm;
1272 super->print();
1273 sub->print();
1274 fatal("%s: %s implements %s: is_subtype_of: %d; linear_search: %d; table_lookup: %d",
1275 msg, sub->external_name(), super->external_name(),
1276 sub->is_subtype_of(super), linear_result, table_result);
1277 }