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 _misc_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 _misc_flags.set_is_cloneable_fast(true);
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 Klass::Klass() : _kind(UnknownKlassKind) {
251 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
252 }
253
254 // "Normal" instantiation is preceded by a MetaspaceObj allocation
255 // which zeros out memory - calloc equivalent.
256 // The constructor is also used from CppVtableCloner,
257 // which doesn't zero out the memory before calling the constructor.
258 Klass::Klass(KlassKind kind) : _kind(kind),
259 _shared_class_path_index(-1) {
260 CDS_ONLY(_shared_class_flags = 0;)
261 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
262 _primary_supers[0] = this;
263 set_super_check_offset(in_bytes(primary_supers_offset()));
264 }
265
266 jint Klass::array_layout_helper(BasicType etype) {
267 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
268 // Note that T_ARRAY is not allowed here.
269 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
270 int esize = type2aelembytes(etype);
271 bool isobj = (etype == T_OBJECT);
272 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
273 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
274
275 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
276 assert(layout_helper_is_array(lh), "correct kind");
277 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
278 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
279 assert(layout_helper_header_size(lh) == hsize, "correct decode");
280 assert(layout_helper_element_type(lh) == etype, "correct decode");
281 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
282
283 return lh;
284 }
285
286 bool Klass::can_be_primary_super_slow() const {
287 if (super() == nullptr)
288 return true;
289 else if (super()->super_depth() >= primary_super_limit()-1)
290 return false;
291 else
292 return true;
293 }
294
295 void Klass::set_secondary_supers(Array<Klass*>* secondaries) {
296 assert(!UseSecondarySupersTable || secondaries == nullptr, "");
297 set_secondary_supers(secondaries, SECONDARY_SUPERS_BITMAP_EMPTY);
298 }
299
300 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
301 #ifdef ASSERT
302 if (UseSecondarySupersTable && secondaries != nullptr) {
303 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
304 assert(bitmap == real_bitmap, "must be");
305 assert(secondaries->length() >= (int)population_count(bitmap), "must be");
306 }
307 #endif
308 _bitmap = bitmap;
309 _secondary_supers = secondaries;
310
311 if (secondaries != nullptr) {
312 LogMessage(class, load) msg;
313 NonInterleavingLogStream log {LogLevel::Debug, msg};
314 if (log.is_enabled()) {
315 ResourceMark rm;
316 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
317 print_secondary_supers_on(&log);
318 }
319 }
320 }
321
322 // Hashed secondary superclasses
323 //
324 // We use a compressed 64-entry hash table with linear probing. We
325 // start by creating a hash table in the usual way, followed by a pass
326 // that removes all the null entries. To indicate which entries would
327 // have been null we use a bitmap that contains a 1 in each position
328 // where an entry is present, 0 otherwise. This bitmap also serves as
329 // a kind of Bloom filter, which in many cases allows us quickly to
330 // eliminate the possibility that something is a member of a set of
331 // secondaries.
332 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
333 const int length = secondaries->length();
334
335 if (length == 0) {
336 return SECONDARY_SUPERS_BITMAP_EMPTY;
337 }
338
339 if (length == 1) {
340 int hash_slot = secondaries->at(0)->hash_slot();
341 return uintx(1) << hash_slot;
342 }
343
344 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)
345
346 // Don't attempt to hash a table that's completely full, because in
347 // the case of an absent interface linear probing would not
348 // terminate.
349 if (length >= SECONDARY_SUPERS_TABLE_SIZE) {
350 return SECONDARY_SUPERS_BITMAP_FULL;
351 }
352
353 {
354 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time());
355
356 ResourceMark rm;
357 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
358 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
359 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
360
361 for (int j = 0; j < length; j++) {
362 Klass* k = secondaries->at(j);
363 hash_insert(k, hashed_secondaries, bitmap);
364 }
365
366 // Pack the hashed secondaries array by copying it into the
367 // secondaries array, sans nulls, if modification is allowed.
368 // Otherwise, validate the order.
369 int i = 0;
370 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
371 bool has_element = ((bitmap >> slot) & 1) != 0;
372 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
373 if (has_element) {
374 Klass* k = hashed_secondaries->at(slot);
375 if (rewrite) {
376 secondaries->at_put(i, k);
377 } else if (secondaries->at(i) != k) {
378 assert(false, "broken secondary supers hash table");
379 return SECONDARY_SUPERS_BITMAP_FULL;
380 }
381 i++;
382 }
383 }
384 assert(i == secondaries->length(), "mismatch");
385
386 return bitmap;
387 }
388 }
389
390 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
391 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
392
393 int dist = 0;
394 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
395 Klass* existing = secondaries->at(slot);
396 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
397 if (existing == nullptr) { // no conflict
398 secondaries->at_put(slot, klass);
399 bitmap |= uintx(1) << slot;
400 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
401 return;
402 } else {
403 // Use Robin Hood hashing to minimize the worst case search.
404 // Also, every permutation of the insertion sequence produces
405 // the same final Robin Hood hash table, provided that a
406 // consistent tie breaker is used.
407 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
408 if (existing_dist < dist
409 // This tie breaker ensures that the hash order is maintained.
410 || ((existing_dist == dist)
411 && (uintptr_t(existing) < uintptr_t(klass)))) {
412 Klass* tmp = secondaries->at(slot);
413 secondaries->at_put(slot, klass);
414 klass = tmp;
415 dist = existing_dist;
416 }
417 ++dist;
418 }
419 }
420 }
421
422 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
423 GrowableArray<Klass*>* primaries,
424 GrowableArray<Klass*>* secondaries,
425 uintx& bitmap, TRAPS) {
426 int new_length = primaries->length() + secondaries->length();
427 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
428
429 // Combine the two arrays into a metadata object to pack the array.
430 // The primaries are added in the reverse order, then the secondaries.
431 int fill_p = primaries->length();
432 for (int j = 0; j < fill_p; j++) {
433 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
434 }
435 for( int j = 0; j < secondaries->length(); j++ ) {
436 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
437 }
438 #ifdef ASSERT
439 // We must not copy any null placeholders left over from bootstrap.
440 for (int j = 0; j < secondary_supers->length(); j++) {
441 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
442 }
443 #endif
444
445 if (UseSecondarySupersTable) {
446 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
447 } else {
448 bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
449 }
450 return secondary_supers;
451 }
452
453 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
454 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
455 }
456
457 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
458 uint8_t hash = k->hash_slot();
459 if (hash > 0) {
460 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
461 }
462 return 0;
463 }
464
465
466 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
467 if (k == nullptr) {
468 set_super(nullptr);
469 _primary_supers[0] = this;
470 assert(super_depth() == 0, "Object must already be initialized properly");
471 } else if (k != super() || k == vmClasses::Object_klass()) {
472 assert(super() == nullptr || super() == vmClasses::Object_klass(),
473 "initialize this only once to a non-trivial value");
474 set_super(k);
475 Klass* sup = k;
476 int sup_depth = sup->super_depth();
477 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
478 if (!can_be_primary_super_slow())
479 my_depth = primary_super_limit();
480 for (juint i = 0; i < my_depth; i++) {
481 _primary_supers[i] = sup->_primary_supers[i];
482 }
483 Klass* *super_check_cell;
484 if (my_depth < primary_super_limit()) {
485 _primary_supers[my_depth] = this;
486 super_check_cell = &_primary_supers[my_depth];
487 } else {
488 // Overflow of the primary_supers array forces me to be secondary.
489 super_check_cell = &_secondary_super_cache;
490 }
491 set_super_check_offset(u4((address)super_check_cell - (address) this));
492
493 #ifdef ASSERT
494 {
495 juint j = super_depth();
496 assert(j == my_depth, "computed accessor gets right answer");
497 Klass* t = this;
498 while (!t->can_be_primary_super()) {
499 t = t->super();
500 j = t->super_depth();
501 }
502 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
503 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
504 }
505 while (t != nullptr) {
506 assert(primary_super_of_depth(j) == t, "super list initialization");
507 t = t->super();
508 --j;
509 }
510 assert(j == (juint)-1, "correct depth count");
511 }
512 #endif
513 }
514
515 if (secondary_supers() == nullptr) {
516
517 // Now compute the list of secondary supertypes.
518 // Secondaries can occasionally be on the super chain,
519 // if the inline "_primary_supers" array overflows.
520 int extras = 0;
521 Klass* p;
522 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
523 ++extras;
524 }
525
526 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
527
528 // Compute the "real" non-extra secondaries.
529 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
530 if (secondaries == nullptr) {
531 // secondary_supers set by compute_secondary_supers
532 return;
533 }
534
535 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
536
537 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
538 int i; // Scan for overflow primaries being duplicates of 2nd'arys
539
540 // This happens frequently for very deeply nested arrays: the
541 // primary superclass chain overflows into the secondary. The
542 // secondary list contains the element_klass's secondaries with
543 // an extra array dimension added. If the element_klass's
544 // secondary list already contains some primary overflows, they
545 // (with the extra level of array-ness) will collide with the
546 // normal primary superclass overflows.
547 for( i = 0; i < secondaries->length(); i++ ) {
548 if( secondaries->at(i) == p )
549 break;
550 }
551 if( i < secondaries->length() )
552 continue; // It's a dup, don't put it in
553 primaries->push(p);
554 }
555 // Combine the two arrays into a metadata object to pack the array.
556 uintx bitmap = 0;
557 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
558 set_secondary_supers(s2, bitmap);
559 }
560 }
561
562 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
563 Array<InstanceKlass*>* transitive_interfaces) {
564 assert(num_extra_slots == 0, "override for complex klasses");
565 assert(transitive_interfaces == nullptr, "sanity");
566 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
567 return nullptr;
568 }
569
570
571 // superklass links
572 InstanceKlass* Klass::superklass() const {
573 assert(super() == nullptr || super()->is_instance_klass(), "must be instance klass");
574 return _super == nullptr ? nullptr : InstanceKlass::cast(_super);
575 }
576
577 // subklass links. Used by the compiler (and vtable initialization)
578 // May be cleaned concurrently, so must use the Compile_lock.
579 // The log parameter is for clean_weak_klass_links to report unlinked classes.
580 Klass* Klass::subklass(bool log) const {
581 // Need load_acquire on the _subklass, because it races with inserts that
582 // publishes freshly initialized data.
583 for (Klass* chain = Atomic::load_acquire(&_subklass);
584 chain != nullptr;
585 // Do not need load_acquire on _next_sibling, because inserts never
586 // create _next_sibling edges to dead data.
587 chain = Atomic::load(&chain->_next_sibling))
588 {
589 if (chain->is_loader_alive()) {
590 return chain;
591 } else if (log) {
592 if (log_is_enabled(Trace, class, unload)) {
593 ResourceMark rm;
594 log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
595 }
596 }
597 }
598 return nullptr;
599 }
600
601 Klass* Klass::next_sibling(bool log) const {
602 // Do not need load_acquire on _next_sibling, because inserts never
603 // create _next_sibling edges to dead data.
604 for (Klass* chain = Atomic::load(&_next_sibling);
605 chain != nullptr;
606 chain = Atomic::load(&chain->_next_sibling)) {
607 // Only return alive klass, there may be stale klass
608 // in this chain if cleaned concurrently.
609 if (chain->is_loader_alive()) {
610 return chain;
611 } else if (log) {
612 if (log_is_enabled(Trace, class, unload)) {
613 ResourceMark rm;
614 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
615 }
616 }
617 }
618 return nullptr;
619 }
620
621 void Klass::set_subklass(Klass* s) {
622 assert(s != this, "sanity check");
623 Atomic::release_store(&_subklass, s);
624 }
625
626 void Klass::set_next_sibling(Klass* s) {
627 assert(s != this, "sanity check");
628 // Does not need release semantics. If used by cleanup, it will link to
629 // already safely published data, and if used by inserts, will be published
630 // safely using cmpxchg.
631 Atomic::store(&_next_sibling, s);
632 }
633
634 void Klass::append_to_sibling_list() {
635 if (Universe::is_fully_initialized()) {
636 assert_locked_or_safepoint(Compile_lock);
637 }
638 debug_only(verify();)
639 // add ourselves to superklass' subklass list
640 InstanceKlass* super = superklass();
641 if (super == nullptr) return; // special case: class Object
642 assert((!super->is_interface() // interfaces cannot be supers
643 && (super->superklass() == nullptr || !is_interface())),
644 "an interface can only be a subklass of Object");
645
646 // Make sure there is no stale subklass head
647 super->clean_subklass();
648
649 for (;;) {
650 Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
651 if (prev_first_subklass != nullptr) {
652 // set our sibling to be the superklass' previous first subklass
653 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
654 set_next_sibling(prev_first_subklass);
655 }
656 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
657 // are ever created to not alive klasses. This is an important invariant of the lock-free
658 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
659 if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
660 return;
661 }
662 }
663 debug_only(verify();)
664 }
665
666 void Klass::clean_subklass() {
667 for (;;) {
668 // Need load_acquire, due to contending with concurrent inserts
669 Klass* subklass = Atomic::load_acquire(&_subklass);
670 if (subklass == nullptr || subklass->is_loader_alive()) {
671 return;
672 }
673 // Try to fix _subklass until it points at something not dead.
674 Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
675 }
676 }
677
678 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
679 if (!ClassUnloading || !unloading_occurred) {
680 return;
681 }
682
683 Klass* root = vmClasses::Object_klass();
684 Stack<Klass*, mtGC> stack;
685
686 stack.push(root);
687 while (!stack.is_empty()) {
688 Klass* current = stack.pop();
689
690 assert(current->is_loader_alive(), "just checking, this should be live");
691
692 // Find and set the first alive subklass
693 Klass* sub = current->subklass(true);
694 current->clean_subklass();
695 if (sub != nullptr) {
696 stack.push(sub);
697 }
698
699 // Find and set the first alive sibling
700 Klass* sibling = current->next_sibling(true);
701 current->set_next_sibling(sibling);
702 if (sibling != nullptr) {
703 stack.push(sibling);
704 }
705
706 // Clean the implementors list and method data.
707 if (clean_alive_klasses && current->is_instance_klass()) {
708 InstanceKlass* ik = InstanceKlass::cast(current);
709 ik->clean_weak_instanceklass_links();
710
711 // JVMTI RedefineClasses creates previous versions that are not in
712 // the class hierarchy, so process them here.
713 while ((ik = ik->previous_versions()) != nullptr) {
714 ik->clean_weak_instanceklass_links();
715 }
716 }
717 }
718 }
719
720 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
721 if (log_is_enabled(Trace, cds)) {
722 ResourceMark rm;
723 log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
724 }
725
726 it->push(&_name);
727 it->push(&_secondary_supers);
728 for (int i = 0; i < _primary_super_limit; i++) {
729 it->push(&_primary_supers[i]);
730 }
731 it->push(&_super);
732 if (!CDSConfig::is_dumping_archive()) {
733 // If dumping archive, these may point to excluded classes. There's no need
734 // to follow these pointers anyway, as they will be set to null in
735 // remove_unshareable_info().
736 it->push((Klass**)&_subklass);
737 it->push((Klass**)&_next_sibling);
738 it->push(&_next_link);
739 }
740
741 vtableEntry* vt = start_of_vtable();
742 for (int i=0; i<vtable_length(); i++) {
743 it->push(vt[i].method_addr());
744 }
745 }
746
747 #if INCLUDE_CDS
748 void Klass::remove_unshareable_info() {
749 assert(CDSConfig::is_dumping_archive(),
750 "only called during CDS dump time");
751 JFR_ONLY(REMOVE_ID(this);)
752 if (log_is_enabled(Trace, cds, unshareable)) {
753 ResourceMark rm;
754 log_trace(cds, unshareable)("remove: %s", external_name());
755 }
756
757 // _secondary_super_cache may be updated by an is_subtype_of() call
758 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
759 // null and let it be repopulated at runtime.
760 set_secondary_super_cache(nullptr);
761
762 set_subklass(nullptr);
763 set_next_sibling(nullptr);
764 set_next_link(nullptr);
765
766 // Null out class_loader_data because we don't share that yet.
767 set_class_loader_data(nullptr);
768 set_is_shared();
769
770 // FIXME: validation in Klass::hash_secondary_supers() may fail for shared klasses.
771 // Even though the bitmaps always match, the canonical order of elements in the table
772 // is not guaranteed to stay the same (see tie breaker during Robin Hood hashing in Klass::hash_insert).
773 //assert(compute_secondary_supers_bitmap(secondary_supers()) == _bitmap, "broken table");
774 }
775
776 void Klass::remove_java_mirror() {
777 assert(CDSConfig::is_dumping_archive(), "sanity");
778 if (log_is_enabled(Trace, cds, unshareable)) {
779 ResourceMark rm;
780 log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
781 }
782 // Just null out the mirror. The class_loader_data() no longer exists.
783 clear_java_mirror_handle();
784 }
785
786 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
787 assert(is_klass(), "ensure C++ vtable is restored");
788 assert(is_shared(), "must be set");
789 assert(secondary_supers()->length() >= (int)population_count(_bitmap), "must be");
790 JFR_ONLY(RESTORE_ID(this);)
791 if (log_is_enabled(Trace, cds, unshareable)) {
792 ResourceMark rm(THREAD);
793 oop class_loader = loader_data->class_loader();
794 log_trace(cds, unshareable)("restore: %s with class loader: %s", external_name(),
795 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
796 }
797
798 // If an exception happened during CDS restore, some of these fields may already be
799 // set. We leave the class on the CLD list, even if incomplete so that we don't
800 // modify the CLD list outside a safepoint.
801 if (class_loader_data() == nullptr) {
802 set_class_loader_data(loader_data);
803
804 // Add to class loader list first before creating the mirror
805 // (same order as class file parsing)
806 loader_data->add_class(this);
807 }
808
809 Handle loader(THREAD, loader_data->class_loader());
810 ModuleEntry* module_entry = nullptr;
811 Klass* k = this;
812 if (k->is_objArray_klass()) {
813 k = ObjArrayKlass::cast(k)->bottom_klass();
814 }
815 // Obtain klass' module.
816 if (k->is_instance_klass()) {
817 InstanceKlass* ik = (InstanceKlass*) k;
818 module_entry = ik->module();
819 } else {
820 module_entry = ModuleEntryTable::javabase_moduleEntry();
821 }
822 // Obtain java.lang.Module, if available
823 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module() : (oop)nullptr));
824
825 if (this->has_archived_mirror_index()) {
826 ResourceMark rm(THREAD);
827 log_debug(cds, mirror)("%s has raw archived mirror", external_name());
828 if (ArchiveHeapLoader::is_in_use()) {
829 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
830 protection_domain,
831 CHECK);
832 if (present) {
833 return;
834 }
835 }
836
837 // No archived mirror data
838 log_debug(cds, mirror)("No archived mirror data for %s", external_name());
839 clear_java_mirror_handle();
840 this->clear_archived_mirror_index();
841 }
842
843 // Only recreate it if not present. A previous attempt to restore may have
844 // gotten an OOM later but keep the mirror if it was created.
845 if (java_mirror() == nullptr) {
846 ResourceMark rm(THREAD);
847 log_trace(cds, mirror)("Recreate mirror for %s", external_name());
848 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
849 }
850 }
851 #endif // INCLUDE_CDS
852
853 #if INCLUDE_CDS_JAVA_HEAP
854 oop Klass::archived_java_mirror() {
855 assert(has_archived_mirror_index(), "must have archived mirror");
856 return HeapShared::get_root(_archived_mirror_index);
857 }
858
859 void Klass::clear_archived_mirror_index() {
860 if (_archived_mirror_index >= 0) {
861 HeapShared::clear_root(_archived_mirror_index);
862 }
863 _archived_mirror_index = -1;
864 }
865
866 // No GC barrier
867 void Klass::set_archived_java_mirror(int mirror_index) {
868 assert(CDSConfig::is_dumping_heap(), "sanity");
869 _archived_mirror_index = mirror_index;
870 }
871 #endif // INCLUDE_CDS_JAVA_HEAP
872
873 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
874 if (length > max_length) {
875 if (!THREAD->is_in_internal_oome_mark()) {
876 report_java_out_of_memory("Requested array size exceeds VM limit");
877 JvmtiExport::post_array_size_exhausted();
878 THROW_OOP(Universe::out_of_memory_error_array_size());
879 } else {
880 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
881 }
882 } else if (length < 0) {
883 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
884 }
885 }
886
887 // Replace the last '+' char with '/'.
888 static char* convert_hidden_name_to_java(Symbol* name) {
889 size_t name_len = name->utf8_length();
890 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
891 name->as_klass_external_name(result, (int)name_len + 1);
892 for (int index = (int)name_len; index > 0; index--) {
893 if (result[index] == '+') {
894 result[index] = JVM_SIGNATURE_SLASH;
895 break;
896 }
897 }
898 return result;
899 }
900
901 // In product mode, this function doesn't have virtual function calls so
902 // there might be some performance advantage to handling InstanceKlass here.
903 const char* Klass::external_name() const {
904 if (is_instance_klass()) {
905 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
906 if (ik->is_hidden()) {
907 char* result = convert_hidden_name_to_java(name());
908 return result;
909 }
910 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
911 char* result = convert_hidden_name_to_java(name());
912 return result;
913 }
914 if (name() == nullptr) return "<unknown>";
915 return name()->as_klass_external_name();
916 }
917
918 const char* Klass::signature_name() const {
919 if (name() == nullptr) return "<unknown>";
920 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
921 size_t name_len = name()->utf8_length();
922 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
923 name()->as_C_string(result, (int)name_len + 1);
924 for (int index = (int)name_len; index > 0; index--) {
925 if (result[index] == '+') {
926 result[index] = JVM_SIGNATURE_DOT;
927 break;
928 }
929 }
930 return result;
931 }
932 return name()->as_C_string();
933 }
934
935 const char* Klass::external_kind() const {
936 if (is_interface()) return "interface";
937 if (is_abstract()) return "abstract class";
938 return "class";
939 }
940
941 // Unless overridden, jvmti_class_status has no flags set.
942 jint Klass::jvmti_class_status() const {
943 return 0;
944 }
945
946
947 // Printing
948
949 void Klass::print_on(outputStream* st) const {
950 ResourceMark rm;
951 // print title
952 st->print("%s", internal_name());
953 print_address_on(st);
954 st->cr();
955 }
956
957 #define BULLET " - "
958
959 // Caller needs ResourceMark
960 void Klass::oop_print_on(oop obj, outputStream* st) {
961 // print title
962 st->print_cr("%s ", internal_name());
963 obj->print_address_on(st);
964
965 if (WizardMode) {
966 // print header
967 obj->mark().print_on(st);
968 st->cr();
969 }
970
971 // print class
972 st->print(BULLET"klass: ");
973 obj->klass()->print_value_on(st);
974 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr();
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 }