1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "cds/cdsConfig.hpp"
26 #include "cds/heapShared.inline.hpp"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/classLoaderData.inline.hpp"
29 #include "classfile/classLoaderDataGraph.inline.hpp"
30 #include "classfile/javaClasses.inline.hpp"
31 #include "classfile/moduleEntry.hpp"
32 #include "classfile/systemDictionary.hpp"
33 #include "classfile/systemDictionaryShared.hpp"
34 #include "classfile/vmClasses.hpp"
35 #include "classfile/vmSymbols.hpp"
36 #include "gc/shared/collectedHeap.inline.hpp"
37 #include "jvm_io.h"
38 #include "logging/log.hpp"
39 #include "memory/metadataFactory.hpp"
40 #include "memory/metaspaceClosure.hpp"
41 #include "memory/oopFactory.hpp"
42 #include "memory/resourceArea.hpp"
43 #include "memory/universe.hpp"
44 #include "oops/compressedKlass.inline.hpp"
45 #include "oops/compressedOops.inline.hpp"
46 #include "oops/instanceKlass.hpp"
47 #include "oops/klass.inline.hpp"
48 #include "oops/objArrayKlass.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "oops/oopHandle.inline.hpp"
51 #include "prims/jvmtiExport.hpp"
52 #include "runtime/atomicAccess.hpp"
53 #include "runtime/handles.inline.hpp"
54 #include "runtime/perfData.hpp"
55 #include "utilities/macros.hpp"
56 #include "utilities/powerOfTwo.hpp"
57 #include "utilities/rotate_bits.hpp"
58 #include "utilities/stack.inline.hpp"
59
60 #if INCLUDE_JFR
61 #include "jfr/jfr.hpp"
62 #endif
63
64 void Klass::set_java_mirror(Handle m) {
65 assert(!m.is_null(), "New mirror should never be null.");
66 assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
67 _java_mirror = class_loader_data()->add_handle(m);
68 }
69
70 bool Klass::is_cloneable() const {
71 return _misc_flags.is_cloneable_fast() ||
72 is_subtype_of(vmClasses::Cloneable_klass());
73 }
74
75 void Klass::set_is_cloneable() {
76 if (name() == vmSymbols::java_lang_invoke_MemberName()) {
77 assert(is_final(), "no subclasses allowed");
78 // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
79 } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
80 // Reference cloning should not be intrinsified and always happen in JVM_Clone.
81 } else {
82 _misc_flags.set_is_cloneable_fast(true);
83 }
84 }
85
86 uint8_t Klass::compute_hash_slot(Symbol* n) {
87 uint hash_code;
88 // Special cases for the two superclasses of all Array instances.
89 // Code elsewhere assumes, for all instances of ArrayKlass, that
90 // these two interfaces will be in this order.
91
92 // We ensure there are some empty slots in the hash table between
93 // these two very common interfaces because if they were adjacent
94 // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1
95 // would result in a probe length of 3.
96 if (n == vmSymbols::java_lang_Cloneable()) {
97 hash_code = 0;
98 } else if (n == vmSymbols::java_io_Serializable()) {
99 hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2;
100 } else {
101 auto s = (const jbyte*) n->bytes();
102 hash_code = java_lang_String::hash_code(s, n->utf8_length());
103 // We use String::hash_code here (rather than e.g.
104 // Symbol::identity_hash()) in order to have a hash code that
105 // does not change from run to run. We want that because the
106 // hash value for a secondary superclass appears in generated
107 // code as a constant.
108
109 // This constant is magic: see Knuth, "Fibonacci Hashing".
110 constexpr uint multiplier
111 = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 ))
112 constexpr uint hash_shift = sizeof(hash_code) * 8 - 6;
113 // The leading bits of the least significant half of the product.
114 hash_code = (hash_code * multiplier) >> hash_shift;
115
116 if (StressSecondarySupers) {
117 // Generate many hash collisions in order to stress-test the
118 // linear search fallback.
119 hash_code = hash_code % 3;
120 hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3);
121 }
122 }
123
124 return (hash_code & SECONDARY_SUPERS_TABLE_MASK);
125 }
126
127 void Klass::set_name(Symbol* n) {
128 _name = n;
129
130 if (_name != nullptr) {
131 _name->increment_refcount();
132 }
133
134 {
135 elapsedTimer selftime;
136 selftime.start();
137
138 _hash_slot = compute_hash_slot(n);
139 assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required");
140
141 selftime.stop();
142 if (UsePerfData) {
143 ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks());
144 }
145 }
146
147 if (CDSConfig::is_dumping_archive() && is_instance_klass()) {
148 SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
149 }
150 }
151
152 bool Klass::is_subclass_of(const Klass* k) const {
153 // Run up the super chain and check
154 if (this == k) return true;
155
156 Klass* t = const_cast<Klass*>(this)->super();
157
158 while (t != nullptr) {
159 if (t == k) return true;
160 t = t->super();
161 }
162 return false;
163 }
164
165 void Klass::release_C_heap_structures(bool release_constant_pool) {
166 if (_name != nullptr) _name->decrement_refcount();
167 }
168
169 bool Klass::linear_search_secondary_supers(const Klass* k) const {
170 // Scan the array-of-objects for a match
171 // FIXME: We could do something smarter here, maybe a vectorized
172 // comparison or a binary search, but is that worth any added
173 // complexity?
174 int cnt = secondary_supers()->length();
175 for (int i = 0; i < cnt; i++) {
176 if (secondary_supers()->at(i) == k) {
177 return true;
178 }
179 }
180 return false;
181 }
182
183 // Given a secondary superklass k, an initial array index, and an
184 // occupancy bitmap rotated such that Bit 1 is the next bit to test,
185 // search for k.
186 bool Klass::fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const {
187 // Once the occupancy bitmap is almost full, it's faster to use a
188 // linear search.
189 if (secondary_supers()->length() > SECONDARY_SUPERS_TABLE_SIZE - 2) {
190 return linear_search_secondary_supers(k);
191 }
192
193 // This is conventional linear probing, but instead of terminating
194 // when a null entry is found in the table, we maintain a bitmap
195 // in which a 0 indicates missing entries.
196
197 precond((int)population_count(rotated_bitmap) == secondary_supers()->length());
198
199 // The check for secondary_supers()->length() <= SECONDARY_SUPERS_TABLE_SIZE - 2
200 // at the start of this function guarantees there are 0s in the
201 // bitmap, so this loop eventually terminates.
202 while ((rotated_bitmap & 2) != 0) {
203 if (++index == secondary_supers()->length()) {
204 index = 0;
205 }
206 if (secondary_supers()->at(index) == k) {
207 return true;
208 }
209 rotated_bitmap = rotate_right(rotated_bitmap, 1);
210 }
211 return false;
212 }
213
214 // Return self, except for abstract classes with exactly 1
215 // implementor. Then return the 1 concrete implementation.
216 Klass *Klass::up_cast_abstract() {
217 Klass *r = this;
218 while( r->is_abstract() ) { // Receiver is abstract?
219 Klass *s = r->subklass(); // Check for exactly 1 subklass
220 if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up
221 return this; // Return 'this' as a no-progress flag
222 r = s; // Loop till find concrete class
223 }
224 return r; // Return the 1 concrete class
225 }
226
227 // Find LCA in class hierarchy
228 Klass *Klass::LCA( Klass *k2 ) {
229 Klass *k1 = this;
230 while( 1 ) {
231 if( k1->is_subtype_of(k2) ) return k2;
232 if( k2->is_subtype_of(k1) ) return k1;
233 k1 = k1->super();
234 k2 = k2->super();
235 }
236 }
237
238
239 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
240 ResourceMark rm(THREAD);
241 THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
242 : vmSymbols::java_lang_InstantiationException(), external_name());
243 }
244
245
246 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
247 ResourceMark rm(THREAD);
248 assert(s != nullptr, "Throw NPE!");
249 THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
250 err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
251 }
252
253
254 void Klass::initialize(TRAPS) {
255 ShouldNotReachHere();
256 }
257
258 void Klass::initialize_preemptable(TRAPS) {
259 ShouldNotReachHere();
260 }
261
262 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
263 #ifdef ASSERT
264 tty->print_cr("Error: find_field called on a klass oop."
265 " Likely error: reflection method does not correctly"
266 " wrap return value in a mirror object.");
267 #endif
268 ShouldNotReachHere();
269 return nullptr;
270 }
271
272 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
273 OverpassLookupMode overpass_mode,
274 PrivateLookupMode private_mode) const {
275 #ifdef ASSERT
276 tty->print_cr("Error: uncached_lookup_method called on a klass oop."
277 " Likely error: reflection method does not correctly"
278 " wrap return value in a mirror object.");
279 #endif
280 ShouldNotReachHere();
281 return nullptr;
282 }
283
284 static markWord make_prototype(const Klass* kls) {
285 markWord prototype = markWord::prototype();
286 #ifdef _LP64
287 if (UseCompactObjectHeaders) {
288 // With compact object headers, the narrow Klass ID is part of the mark word.
289 // We therefore seed the mark word with the narrow Klass ID.
290 precond(CompressedKlassPointers::is_encodable(kls));
291 const narrowKlass nk = CompressedKlassPointers::encode(const_cast<Klass*>(kls));
292 prototype = prototype.set_narrow_klass(nk);
293 }
294 #endif
295 return prototype;
296 }
297
298 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
299 return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
300 }
301
302 Klass::Klass() : _kind(UnknownKlassKind) {
303 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
304 }
305
306 // "Normal" instantiation is preceded by a MetaspaceObj allocation
307 // which zeros out memory - calloc equivalent.
308 // The constructor is also used from CppVtableCloner,
309 // which doesn't zero out the memory before calling the constructor.
310 Klass::Klass(KlassKind kind) : _kind(kind),
311 _prototype_header(make_prototype(this)),
312 _shared_class_path_index(-1) {
313 CDS_ONLY(_aot_class_flags = 0;)
314 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
315 _primary_supers[0] = this;
316 set_super_check_offset(in_bytes(primary_supers_offset()));
317 }
318
319 jint Klass::array_layout_helper(BasicType etype) {
320 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
321 // Note that T_ARRAY is not allowed here.
322 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
323 int esize = type2aelembytes(etype);
324 bool isobj = (etype == T_OBJECT);
325 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
326 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
327
328 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
329 assert(layout_helper_is_array(lh), "correct kind");
330 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
331 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
332 assert(layout_helper_header_size(lh) == hsize, "correct decode");
333 assert(layout_helper_element_type(lh) == etype, "correct decode");
334 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
335
336 return lh;
337 }
338
339 int Klass::modifier_flags() const {
340 int mods = java_lang_Class::modifiers(java_mirror());
341 assert(mods == compute_modifier_flags(), "should be same");
342 return mods;
343 }
344
345 bool Klass::can_be_primary_super_slow() const {
346 if (super() == nullptr)
347 return true;
348 else if (super()->super_depth() >= primary_super_limit()-1)
349 return false;
350 else
351 return true;
352 }
353
354 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
355 #ifdef ASSERT
356 if (secondaries != nullptr) {
357 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
358 assert(bitmap == real_bitmap, "must be");
359 assert(secondaries->length() >= (int)population_count(bitmap), "must be");
360 }
361 #endif
362 _secondary_supers_bitmap = bitmap;
363 _secondary_supers = secondaries;
364
365 if (secondaries != nullptr) {
366 LogMessage(class, load) msg;
367 NonInterleavingLogStream log {LogLevel::Debug, msg};
368 if (log.is_enabled()) {
369 ResourceMark rm;
370 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
371 print_secondary_supers_on(&log);
372 }
373 }
374 }
375
376 // Hashed secondary superclasses
377 //
378 // We use a compressed 64-entry hash table with linear probing. We
379 // start by creating a hash table in the usual way, followed by a pass
380 // that removes all the null entries. To indicate which entries would
381 // have been null we use a bitmap that contains a 1 in each position
382 // where an entry is present, 0 otherwise. This bitmap also serves as
383 // a kind of Bloom filter, which in many cases allows us quickly to
384 // eliminate the possibility that something is a member of a set of
385 // secondaries.
386 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
387 const int length = secondaries->length();
388
389 if (length == 0) {
390 return SECONDARY_SUPERS_BITMAP_EMPTY;
391 }
392
393 if (length == 1) {
394 int hash_slot = secondaries->at(0)->hash_slot();
395 return uintx(1) << hash_slot;
396 }
397
398 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)
399
400 // Don't attempt to hash a table that's completely full, because in
401 // the case of an absent interface linear probing would not
402 // terminate.
403 if (length >= SECONDARY_SUPERS_TABLE_SIZE) {
404 return SECONDARY_SUPERS_BITMAP_FULL;
405 }
406
407 {
408 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time());
409
410 ResourceMark rm;
411 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
412 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
413 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
414
415 for (int j = 0; j < length; j++) {
416 Klass* k = secondaries->at(j);
417 hash_insert(k, hashed_secondaries, bitmap);
418 }
419
420 // Pack the hashed secondaries array by copying it into the
421 // secondaries array, sans nulls, if modification is allowed.
422 // Otherwise, validate the order.
423 int i = 0;
424 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
425 bool has_element = ((bitmap >> slot) & 1) != 0;
426 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
427 if (has_element) {
428 Klass* k = hashed_secondaries->at(slot);
429 if (rewrite) {
430 secondaries->at_put(i, k);
431 } else if (secondaries->at(i) != k) {
432 assert(false, "broken secondary supers hash table");
433 return SECONDARY_SUPERS_BITMAP_FULL;
434 }
435 i++;
436 }
437 }
438 assert(i == secondaries->length(), "mismatch");
439 postcond((int)population_count(bitmap) == secondaries->length());
440
441 return bitmap;
442 }
443 }
444
445 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
446 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
447
448 int dist = 0;
449 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
450 Klass* existing = secondaries->at(slot);
451 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
452 if (existing == nullptr) { // no conflict
453 secondaries->at_put(slot, klass);
454 bitmap |= uintx(1) << slot;
455 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
456 return;
457 } else {
458 // Use Robin Hood hashing to minimize the worst case search.
459 // Also, every permutation of the insertion sequence produces
460 // the same final Robin Hood hash table, provided that a
461 // consistent tie breaker is used.
462 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
463 if (existing_dist < dist
464 // This tie breaker ensures that the hash order is maintained.
465 || ((existing_dist == dist)
466 && (uintptr_t(existing) < uintptr_t(klass)))) {
467 Klass* tmp = secondaries->at(slot);
468 secondaries->at_put(slot, klass);
469 klass = tmp;
470 dist = existing_dist;
471 }
472 ++dist;
473 }
474 }
475 }
476
477 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
478 GrowableArray<Klass*>* primaries,
479 GrowableArray<Klass*>* secondaries,
480 uintx& bitmap, TRAPS) {
481 int new_length = primaries->length() + secondaries->length();
482 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
483
484 // Combine the two arrays into a metadata object to pack the array.
485 // The primaries are added in the reverse order, then the secondaries.
486 int fill_p = primaries->length();
487 for (int j = 0; j < fill_p; j++) {
488 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
489 }
490 for( int j = 0; j < secondaries->length(); j++ ) {
491 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
492 }
493 #ifdef ASSERT
494 // We must not copy any null placeholders left over from bootstrap.
495 for (int j = 0; j < secondary_supers->length(); j++) {
496 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
497 }
498 #endif
499
500 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
501 return secondary_supers;
502 }
503
504 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
505 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
506 }
507
508 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
509 uint8_t hash = k->hash_slot();
510 if (hash > 0) {
511 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
512 }
513 return 0;
514 }
515
516
517 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
518 if (k == nullptr) {
519 set_super(nullptr);
520 _primary_supers[0] = this;
521 assert(super_depth() == 0, "Object must already be initialized properly");
522 } else if (k != super() || k == vmClasses::Object_klass()) {
523 assert(super() == nullptr || super() == vmClasses::Object_klass(),
524 "initialize this only once to a non-trivial value");
525 set_super(k);
526 Klass* sup = k;
527 int sup_depth = sup->super_depth();
528 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
529 if (!can_be_primary_super_slow())
530 my_depth = primary_super_limit();
531 for (juint i = 0; i < my_depth; i++) {
532 _primary_supers[i] = sup->_primary_supers[i];
533 }
534 Klass* *super_check_cell;
535 if (my_depth < primary_super_limit()) {
536 _primary_supers[my_depth] = this;
537 super_check_cell = &_primary_supers[my_depth];
538 } else {
539 // Overflow of the primary_supers array forces me to be secondary.
540 super_check_cell = &_secondary_super_cache;
541 }
542 set_super_check_offset(u4((address)super_check_cell - (address) this));
543
544 #ifdef ASSERT
545 {
546 juint j = super_depth();
547 assert(j == my_depth, "computed accessor gets right answer");
548 Klass* t = this;
549 while (!t->can_be_primary_super()) {
550 t = t->super();
551 j = t->super_depth();
552 }
553 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
554 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
555 }
556 while (t != nullptr) {
557 assert(primary_super_of_depth(j) == t, "super list initialization");
558 t = t->super();
559 --j;
560 }
561 assert(j == (juint)-1, "correct depth count");
562 }
563 #endif
564 }
565
566 if (secondary_supers() == nullptr) {
567
568 // Now compute the list of secondary supertypes.
569 // Secondaries can occasionally be on the super chain,
570 // if the inline "_primary_supers" array overflows.
571 int extras = 0;
572 Klass* p;
573 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
574 ++extras;
575 }
576
577 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
578
579 // Compute the "real" non-extra secondaries.
580 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
581 if (secondaries == nullptr) {
582 // secondary_supers set by compute_secondary_supers
583 return;
584 }
585
586 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
587
588 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
589 int i; // Scan for overflow primaries being duplicates of 2nd'arys
590
591 // This happens frequently for very deeply nested arrays: the
592 // primary superclass chain overflows into the secondary. The
593 // secondary list contains the element_klass's secondaries with
594 // an extra array dimension added. If the element_klass's
595 // secondary list already contains some primary overflows, they
596 // (with the extra level of array-ness) will collide with the
597 // normal primary superclass overflows.
598 for( i = 0; i < secondaries->length(); i++ ) {
599 if( secondaries->at(i) == p )
600 break;
601 }
602 if( i < secondaries->length() )
603 continue; // It's a dup, don't put it in
604 primaries->push(p);
605 }
606 // Combine the two arrays into a metadata object to pack the array.
607 uintx bitmap = 0;
608 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
609 set_secondary_supers(s2, bitmap);
610 }
611 }
612
613 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
614 Array<InstanceKlass*>* transitive_interfaces) {
615 assert(num_extra_slots == 0, "override for complex klasses");
616 assert(transitive_interfaces == nullptr, "sanity");
617 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
618 return nullptr;
619 }
620
621
622 // subklass links. Used by the compiler (and vtable initialization)
623 // May be cleaned concurrently, so must use the Compile_lock.
624 Klass* Klass::subklass() const {
625 // Need load_acquire on the _subklass, because it races with inserts that
626 // publishes freshly initialized data.
627 for (Klass* chain = AtomicAccess::load_acquire(&_subklass);
628 chain != nullptr;
629 // Do not need load_acquire on _next_sibling, because inserts never
630 // create _next_sibling edges to dead data.
631 chain = AtomicAccess::load(&chain->_next_sibling))
632 {
633 if (chain->is_loader_alive()) {
634 return chain;
635 }
636 }
637 return nullptr;
638 }
639
640 Klass* Klass::next_sibling(bool log) const {
641 // Do not need load_acquire on _next_sibling, because inserts never
642 // create _next_sibling edges to dead data.
643 for (Klass* chain = AtomicAccess::load(&_next_sibling);
644 chain != nullptr;
645 chain = AtomicAccess::load(&chain->_next_sibling)) {
646 // Only return alive klass, there may be stale klass
647 // in this chain if cleaned concurrently.
648 if (chain->is_loader_alive()) {
649 return chain;
650 } else if (log) {
651 if (log_is_enabled(Trace, class, unload)) {
652 ResourceMark rm;
653 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
654 }
655 }
656 }
657 return nullptr;
658 }
659
660 void Klass::set_subklass(Klass* s) {
661 assert(s != this, "sanity check");
662 AtomicAccess::release_store(&_subklass, s);
663 }
664
665 void Klass::set_next_sibling(Klass* s) {
666 assert(s != this, "sanity check");
667 // Does not need release semantics. If used by cleanup, it will link to
668 // already safely published data, and if used by inserts, will be published
669 // safely using cmpxchg.
670 AtomicAccess::store(&_next_sibling, s);
671 }
672
673 void Klass::append_to_sibling_list() {
674 if (Universe::is_fully_initialized()) {
675 assert_locked_or_safepoint(Compile_lock);
676 }
677 DEBUG_ONLY(verify();)
678 // add ourselves to super' subklass list
679 InstanceKlass* super = java_super();
680 if (super == nullptr) return; // special case: class Object
681 assert((!super->is_interface() // interfaces cannot be supers
682 && (super->java_super() == nullptr || !is_interface())),
683 "an interface can only be a subklass of Object");
684
685 // Make sure there is no stale subklass head
686 super->clean_subklass();
687
688 for (;;) {
689 Klass* prev_first_subklass = AtomicAccess::load_acquire(&_super->_subklass);
690 if (prev_first_subklass != nullptr) {
691 // set our sibling to be the super' previous first subklass
692 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
693 set_next_sibling(prev_first_subklass);
694 }
695 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
696 // are ever created to not alive klasses. This is an important invariant of the lock-free
697 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
698 if (AtomicAccess::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
699 return;
700 }
701 }
702 DEBUG_ONLY(verify();)
703 }
704
705 // The log parameter is for clean_weak_klass_links to report unlinked classes.
706 Klass* Klass::clean_subklass(bool log) {
707 for (;;) {
708 // Need load_acquire, due to contending with concurrent inserts
709 Klass* subklass = AtomicAccess::load_acquire(&_subklass);
710 if (subklass == nullptr || subklass->is_loader_alive()) {
711 return subklass;
712 }
713 if (log && log_is_enabled(Trace, class, unload)) {
714 ResourceMark rm;
715 log_trace(class, unload)("unlinking class (subclass): %s", subklass->external_name());
716 }
717 // Try to fix _subklass until it points at something not dead.
718 AtomicAccess::cmpxchg(&_subklass, subklass, subklass->next_sibling(log));
719 }
720 }
721
722 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
723 if (!ClassUnloading || !unloading_occurred) {
724 return;
725 }
726
727 Klass* root = vmClasses::Object_klass();
728 Stack<Klass*, mtGC> stack;
729
730 stack.push(root);
731 while (!stack.is_empty()) {
732 Klass* current = stack.pop();
733
734 assert(current->is_loader_alive(), "just checking, this should be live");
735
736 // Find and set the first alive subklass
737 Klass* sub = current->clean_subklass(true);
738 if (sub != nullptr) {
739 stack.push(sub);
740 }
741
742 // Find and set the first alive sibling
743 Klass* sibling = current->next_sibling(true);
744 current->set_next_sibling(sibling);
745 if (sibling != nullptr) {
746 stack.push(sibling);
747 }
748
749 // Clean the implementors list and method data.
750 if (clean_alive_klasses && current->is_instance_klass()) {
751 InstanceKlass* ik = InstanceKlass::cast(current);
752 clean_weak_instanceklass_links(ik);
753 }
754 }
755 }
756
757 void Klass::clean_weak_instanceklass_links(InstanceKlass* ik) {
758 ik->clean_weak_instanceklass_links();
759 // JVMTI RedefineClasses creates previous versions that are not in
760 // the class hierarchy, so process them here.
761 while ((ik = ik->previous_versions()) != nullptr) {
762 ik->clean_weak_instanceklass_links();
763 }
764 }
765
766 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
767 if (log_is_enabled(Trace, aot)) {
768 ResourceMark rm;
769 log_trace(aot)("Iter(Klass): %p (%s)", this, external_name());
770 }
771
772 it->push(&_name);
773 it->push(&_secondary_supers);
774 for (int i = 0; i < _primary_super_limit; i++) {
775 it->push(&_primary_supers[i]);
776 }
777 it->push(&_super);
778 if (!CDSConfig::is_dumping_archive()) {
779 // If dumping archive, these may point to excluded classes. There's no need
780 // to follow these pointers anyway, as they will be set to null in
781 // remove_unshareable_info().
782 it->push((Klass**)&_subklass);
783 it->push((Klass**)&_next_sibling);
784 it->push(&_next_link);
785 }
786
787 vtableEntry* vt = start_of_vtable();
788 for (int i=0; i<vtable_length(); i++) {
789 it->push(vt[i].method_addr());
790 }
791 }
792
793 #if INCLUDE_CDS
794 void Klass::remove_unshareable_info() {
795 assert(CDSConfig::is_dumping_archive(),
796 "only called during CDS dump time");
797 JFR_ONLY(REMOVE_ID(this);)
798 if (log_is_enabled(Trace, aot, unshareable)) {
799 ResourceMark rm;
800 log_trace(aot, unshareable)("remove: %s", external_name());
801 }
802
803 // _secondary_super_cache may be updated by an is_subtype_of() call
804 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
805 // null and let it be repopulated at runtime.
806 set_secondary_super_cache(nullptr);
807
808 set_subklass(nullptr);
809 set_next_sibling(nullptr);
810 set_next_link(nullptr);
811
812 // Null out class_loader_data because we don't share that yet.
813 set_class_loader_data(nullptr);
814 set_in_aot_cache();
815
816 if (CDSConfig::is_dumping_classic_static_archive()) {
817 // "Classic" static archives are required to have deterministic contents.
818 // The elements in _secondary_supers are addresses in the ArchiveBuilder
819 // output buffer, so they should have deterministic values. If we rehash
820 // _secondary_supers, its elements will appear in a deterministic order.
821 //
822 // Note that the bitmap is guaranteed to be deterministic, regardless of the
823 // actual addresses of the elements in _secondary_supers. So rehashing shouldn't
824 // change it.
825 uintx bitmap = hash_secondary_supers(secondary_supers(), true);
826 assert(bitmap == _secondary_supers_bitmap, "bitmap should not be changed due to rehashing");
827 }
828 }
829
830 void Klass::remove_java_mirror() {
831 assert(CDSConfig::is_dumping_archive(), "sanity");
832 if (log_is_enabled(Trace, aot, unshareable)) {
833 ResourceMark rm;
834 log_trace(aot, unshareable)("remove java_mirror: %s", external_name());
835 }
836
837 #if INCLUDE_CDS_JAVA_HEAP
838 _archived_mirror_index = -1;
839 if (CDSConfig::is_dumping_heap()) {
840 Klass* src_k = ArchiveBuilder::current()->get_source_addr(this);
841 oop orig_mirror = src_k->java_mirror();
842 if (orig_mirror == nullptr) {
843 assert(CDSConfig::is_dumping_final_static_archive(), "sanity");
844 if (is_instance_klass()) {
845 assert(InstanceKlass::cast(this)->defined_by_other_loaders(), "sanity");
846 } else {
847 precond(is_objArray_klass());
848 Klass *k = ObjArrayKlass::cast(this)->bottom_klass();
849 precond(k->is_instance_klass());
850 assert(InstanceKlass::cast(k)->defined_by_other_loaders(), "sanity");
851 }
852 } else {
853 oop scratch_mirror = HeapShared::scratch_java_mirror(orig_mirror);
854 if (scratch_mirror != nullptr) {
855 _archived_mirror_index = HeapShared::append_root(scratch_mirror);
856 }
857 }
858 }
859 #endif
860
861 // Just null out the mirror. The class_loader_data() no longer exists.
862 clear_java_mirror_handle();
863 }
864
865 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
866 assert(is_klass(), "ensure C++ vtable is restored");
867 assert(in_aot_cache(), "must be set");
868 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be");
869 if (log_is_enabled(Trace, aot, unshareable)) {
870 ResourceMark rm(THREAD);
871 oop class_loader = loader_data->class_loader();
872 log_trace(aot, unshareable)("restore: %s with class loader: %s", external_name(),
873 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
874 }
875
876 // If an exception happened during CDS restore, some of these fields may already be
877 // set. We leave the class on the CLD list, even if incomplete so that we don't
878 // modify the CLD list outside a safepoint.
879 if (class_loader_data() == nullptr) {
880 set_class_loader_data(loader_data);
881 }
882
883 // Add to class loader list first before creating the mirror
884 // (same order as class file parsing)
885 loader_data->add_class(this);
886
887 JFR_ONLY(Jfr::on_restoration(this, THREAD);)
888
889 Handle loader(THREAD, loader_data->class_loader());
890 ModuleEntry* module_entry = nullptr;
891 Klass* k = this;
892 if (k->is_objArray_klass()) {
893 k = ObjArrayKlass::cast(k)->bottom_klass();
894 }
895 // Obtain klass' module.
896 if (k->is_instance_klass()) {
897 InstanceKlass* ik = (InstanceKlass*) k;
898 module_entry = ik->module();
899 } else {
900 module_entry = ModuleEntryTable::javabase_moduleEntry();
901 }
902 // Obtain java.lang.Module, if available
903 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module_oop() : (oop)nullptr));
904
905 if (this->has_archived_mirror_index()) {
906 ResourceMark rm(THREAD);
907 log_debug(aot, mirror)("%s has raw archived mirror", external_name());
908 if (HeapShared::is_archived_heap_in_use()) {
909 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
910 protection_domain,
911 CHECK);
912 if (present) {
913 return;
914 }
915 }
916
917 // No archived mirror data
918 log_debug(aot, mirror)("No archived mirror data for %s", external_name());
919 clear_java_mirror_handle();
920 this->clear_archived_mirror_index();
921 }
922
923 // Only recreate it if not present. A previous attempt to restore may have
924 // gotten an OOM later but keep the mirror if it was created.
925 if (java_mirror() == nullptr) {
926 ResourceMark rm(THREAD);
927 log_trace(aot, mirror)("Recreate mirror for %s", external_name());
928 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
929 }
930 }
931 #endif // INCLUDE_CDS
932
933 #if INCLUDE_CDS_JAVA_HEAP
934 oop Klass::archived_java_mirror() {
935 assert(has_archived_mirror_index(), "must have archived mirror");
936 return HeapShared::get_root(_archived_mirror_index);
937 }
938
939 void Klass::clear_archived_mirror_index() {
940 if (_archived_mirror_index >= 0) {
941 HeapShared::clear_root(_archived_mirror_index);
942 }
943 _archived_mirror_index = -1;
944 }
945 #endif // INCLUDE_CDS_JAVA_HEAP
946
947 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
948 if (length > max_length) {
949 if (!THREAD->is_in_internal_oome_mark()) {
950 report_java_out_of_memory("Requested array size exceeds VM limit");
951 JvmtiExport::post_array_size_exhausted();
952 THROW_OOP(Universe::out_of_memory_error_array_size());
953 } else {
954 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
955 }
956 } else if (length < 0) {
957 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
958 }
959 }
960
961 // Replace the last '+' char with '/'.
962 static char* convert_hidden_name_to_java(Symbol* name) {
963 size_t name_len = name->utf8_length();
964 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
965 name->as_klass_external_name(result, (int)name_len + 1);
966 for (int index = (int)name_len; index > 0; index--) {
967 if (result[index] == '+') {
968 result[index] = JVM_SIGNATURE_SLASH;
969 break;
970 }
971 }
972 return result;
973 }
974
975 // In product mode, this function doesn't have virtual function calls so
976 // there might be some performance advantage to handling InstanceKlass here.
977 const char* Klass::external_name() const {
978 if (is_instance_klass()) {
979 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
980 if (ik->is_hidden()) {
981 char* result = convert_hidden_name_to_java(name());
982 return result;
983 }
984 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
985 char* result = convert_hidden_name_to_java(name());
986 return result;
987 }
988 if (name() == nullptr) return "<unknown>";
989 return name()->as_klass_external_name();
990 }
991
992 const char* Klass::signature_name() const {
993 if (name() == nullptr) return "<unknown>";
994 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
995 size_t name_len = name()->utf8_length();
996 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
997 name()->as_C_string(result, (int)name_len + 1);
998 for (int index = (int)name_len; index > 0; index--) {
999 if (result[index] == '+') {
1000 result[index] = JVM_SIGNATURE_DOT;
1001 break;
1002 }
1003 }
1004 return result;
1005 }
1006 return name()->as_C_string();
1007 }
1008
1009 const char* Klass::external_kind() const {
1010 if (is_interface()) return "interface";
1011 if (is_abstract()) return "abstract class";
1012 return "class";
1013 }
1014
1015 // Unless overridden, jvmti_class_status has no flags set.
1016 jint Klass::jvmti_class_status() const {
1017 return 0;
1018 }
1019
1020
1021 // Printing
1022
1023 void Klass::print_on(outputStream* st) const {
1024 ResourceMark rm;
1025 // print title
1026 st->print("%s", internal_name());
1027 print_address_on(st);
1028 st->cr();
1029 }
1030
1031 #define BULLET " - "
1032
1033 // Caller needs ResourceMark
1034 void Klass::oop_print_on(oop obj, outputStream* st) {
1035 // print title
1036 st->print_cr("%s ", internal_name());
1037 obj->print_address_on(st);
1038
1039 if (WizardMode) {
1040 // print header
1041 obj->mark().print_on(st);
1042 st->cr();
1043 if (UseCompactObjectHeaders) {
1044 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
1045 st->cr();
1046 }
1047 }
1048
1049 // print class
1050 st->print(BULLET"klass: ");
1051 obj->klass()->print_value_on(st);
1052 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr();
1053 st->cr();
1054 }
1055
1056 void Klass::oop_print_value_on(oop obj, outputStream* st) {
1057 // print title
1058 ResourceMark rm; // Cannot print in debug mode without this
1059 st->print("%s", internal_name());
1060 obj->print_address_on(st);
1061 }
1062
1063 // Verification
1064
1065 void Klass::verify_on(outputStream* st) {
1066
1067 // This can be expensive, but it is worth checking that this klass is actually
1068 // in the CLD graph but not in production.
1069 #ifdef ASSERT
1070 if (UseCompressedClassPointers) {
1071 // Stricter checks for both correct alignment and placement
1072 CompressedKlassPointers::check_encodable(this);
1073 } else {
1074 assert(Metaspace::contains((address)this), "Should be");
1075 }
1076 #endif // ASSERT
1077
1078 guarantee(this->is_klass(),"should be klass");
1079
1080 if (super() != nullptr) {
1081 guarantee(super()->is_klass(), "should be klass");
1082 }
1083 if (secondary_super_cache() != nullptr) {
1084 Klass* ko = secondary_super_cache();
1085 guarantee(ko->is_klass(), "should be klass");
1086 }
1087 for ( uint i = 0; i < primary_super_limit(); i++ ) {
1088 Klass* ko = _primary_supers[i];
1089 if (ko != nullptr) {
1090 guarantee(ko->is_klass(), "should be klass");
1091 }
1092 }
1093
1094 if (java_mirror_no_keepalive() != nullptr) {
1095 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
1096 }
1097 }
1098
1099 void Klass::oop_verify_on(oop obj, outputStream* st) {
1100 guarantee(oopDesc::is_oop(obj), "should be oop");
1101 guarantee(obj->klass()->is_klass(), "klass field is not a klass");
1102 }
1103
1104 // Note: this function is called with an address that may or may not be a Klass.
1105 // The point is not to assert it is but to check if it could be.
1106 bool Klass::is_valid(Klass* k) {
1107 if (!is_aligned(k, sizeof(MetaWord))) return false;
1108 if ((size_t)k < os::min_page_size()) return false;
1109
1110 if (!os::is_readable_range(k, k + 1)) return false;
1111 if (!Metaspace::contains(k)) return false;
1112
1113 if (!Symbol::is_valid(k->name())) return false;
1114 return ClassLoaderDataGraph::is_valid(k->class_loader_data());
1115 }
1116
1117 Method* Klass::method_at_vtable(int index) {
1118 #ifndef PRODUCT
1119 assert(index >= 0, "valid vtable index");
1120 if (DebugVtables) {
1121 verify_vtable_index(index);
1122 }
1123 #endif
1124 return start_of_vtable()[index].method();
1125 }
1126
1127
1128 #ifndef PRODUCT
1129
1130 bool Klass::verify_vtable_index(int i) {
1131 int limit = vtable_length()/vtableEntry::size();
1132 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
1133 return true;
1134 }
1135
1136 #endif // PRODUCT
1137
1138 // Caller needs ResourceMark
1139 // joint_in_module_of_loader provides an optimization if 2 classes are in
1140 // the same module to succinctly print out relevant information about their
1141 // module name and class loader's name_and_id for error messages.
1142 // Format:
1143 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
1144 // are in module <module-name>[@<version>]
1145 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1146 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
1147 assert(module() == class2->module(), "classes do not have the same module");
1148 const char* class1_name = external_name();
1149 size_t len = strlen(class1_name) + 1;
1150
1151 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
1152 len += strlen(class2_description);
1153
1154 len += strlen(" and ");
1155
1156 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1157
1158 // Just return the FQN if error when allocating string
1159 if (joint_description == nullptr) {
1160 return class1_name;
1161 }
1162
1163 jio_snprintf(joint_description, len, "%s and %s",
1164 class1_name,
1165 class2_description);
1166
1167 return joint_description;
1168 }
1169
1170 // Caller needs ResourceMark
1171 // class_in_module_of_loader provides a standard way to include
1172 // relevant information about a class, such as its module name as
1173 // well as its class loader's name_and_id, in error messages and logging.
1174 // Format:
1175 // <fully-qualified-external-class-name> is in module <module-name>[@<version>]
1176 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1177 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
1178 // 1. fully qualified external name of class
1179 const char* klass_name = external_name();
1180 size_t len = strlen(klass_name) + 1;
1181
1182 // 2. module name + @version
1183 const char* module_name = "";
1184 const char* version = "";
1185 bool has_version = false;
1186 bool module_is_named = false;
1187 const char* module_name_phrase = "";
1188 const Klass* bottom_klass = is_objArray_klass() ?
1189 ObjArrayKlass::cast(this)->bottom_klass() : this;
1190 if (bottom_klass->is_instance_klass()) {
1191 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
1192 if (module->is_named()) {
1193 module_is_named = true;
1194 module_name_phrase = "module ";
1195 module_name = module->name()->as_C_string();
1196 len += strlen(module_name);
1197 // Use version if exists and is not a jdk module
1198 if (module->should_show_version()) {
1199 has_version = true;
1200 version = module->version()->as_C_string();
1201 // Include stlen(version) + 1 for the "@"
1202 len += strlen(version) + 1;
1203 }
1204 } else {
1205 module_name = UNNAMED_MODULE;
1206 len += UNNAMED_MODULE_LEN;
1207 }
1208 } else {
1209 // klass is an array of primitives, module is java.base
1210 module_is_named = true;
1211 module_name_phrase = "module ";
1212 module_name = JAVA_BASE_NAME;
1213 len += JAVA_BASE_NAME_LEN;
1214 }
1215
1216 // 3. class loader's name_and_id
1217 ClassLoaderData* cld = class_loader_data();
1218 assert(cld != nullptr, "class_loader_data should not be null");
1219 const char* loader_name_and_id = cld->loader_name_and_id();
1220 len += strlen(loader_name_and_id);
1221
1222 // 4. include parent loader information
1223 const char* parent_loader_phrase = "";
1224 const char* parent_loader_name_and_id = "";
1225 if (include_parent_loader &&
1226 !cld->is_builtin_class_loader_data()) {
1227 oop parent_loader = java_lang_ClassLoader::parent(class_loader());
1228 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
1229 // The parent loader's ClassLoaderData could be null if it is
1230 // a delegating class loader that has never defined a class.
1231 // In this case the loader's name must be obtained via the parent loader's oop.
1232 if (parent_cld == nullptr) {
1233 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
1234 if (cl_name_and_id != nullptr) {
1235 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
1236 }
1237 } else {
1238 parent_loader_name_and_id = parent_cld->loader_name_and_id();
1239 }
1240 parent_loader_phrase = ", parent loader ";
1241 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
1242 }
1243
1244 // Start to construct final full class description string
1245 len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
1246 len += strlen(module_name_phrase) + strlen(" of loader ");
1247
1248 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1249
1250 // Just return the FQN if error when allocating string
1251 if (class_description == nullptr) {
1252 return klass_name;
1253 }
1254
1255 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
1256 klass_name,
1257 (use_are) ? "are" : "is",
1258 module_name_phrase,
1259 module_name,
1260 (has_version) ? "@" : "",
1261 (has_version) ? version : "",
1262 loader_name_and_id,
1263 parent_loader_phrase,
1264 parent_loader_name_and_id);
1265
1266 return class_description;
1267 }
1268
1269 class LookupStats : StackObj {
1270 private:
1271 uint _no_of_samples;
1272 uint _worst;
1273 uint _worst_count;
1274 uint _average;
1275 uint _best;
1276 uint _best_count;
1277 public:
1278 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {}
1279
1280 ~LookupStats() {
1281 assert(_best <= _worst || _no_of_samples == 0, "sanity");
1282 }
1283
1284 void sample(uint value) {
1285 ++_no_of_samples;
1286 _average += value;
1287
1288 if (_worst < value) {
1289 _worst = value;
1290 _worst_count = 1;
1291 } else if (_worst == value) {
1292 ++_worst_count;
1293 }
1294
1295 if (_best > value) {
1296 _best = value;
1297 _best_count = 1;
1298 } else if (_best == value) {
1299 ++_best_count;
1300 }
1301 }
1302
1303 void print_on(outputStream* st) const {
1304 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples);
1305 if (_best_count < _no_of_samples) {
1306 st->print("; average: %4.1f; worst: %2d (%4.1f%%)",
1307 (1.0 * _average) / _no_of_samples,
1308 _worst, (100.0 * _worst_count) / _no_of_samples);
1309 }
1310 }
1311 };
1312
1313 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) {
1314 int num_of_supers = secondary_supers->length();
1315
1316 LookupStats s;
1317 for (int i = 0; i < num_of_supers; i++) {
1318 Klass* secondary_super = secondary_supers->at(i);
1319 int home_slot = Klass::compute_home_slot(secondary_super, bitmap);
1320 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK);
1321 s.sample(score);
1322 }
1323 st->print("positive_lookup: "); s.print_on(st);
1324 }
1325
1326 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) {
1327 assert(~bitmap != 0, "no zeroes");
1328 uintx start = rotate_right(bitmap, slot);
1329 return count_trailing_zeros(~start);
1330 }
1331
1332 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) {
1333 LookupStats s;
1334 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
1335 uint score = compute_distance_to_nearest_zero(slot, bitmap);
1336 s.sample(score);
1337 }
1338 st->print("negative_lookup: "); s.print_on(st);
1339 }
1340
1341 void Klass::print_secondary_supers_on(outputStream* st) const {
1342 if (secondary_supers() != nullptr) {
1343 st->print(" - "); st->print("%d elements;", _secondary_supers->length());
1344 st->print_cr(" bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap);
1345 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY &&
1346 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) {
1347 st->print(" - "); print_positive_lookup_stats(secondary_supers(),
1348 _secondary_supers_bitmap, st); st->cr();
1349 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr();
1350 }
1351 } else {
1352 st->print("null");
1353 }
1354 }
1355
1356 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) {
1357 ResourceMark rm;
1358 super->print();
1359 sub->print();
1360 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d",
1361 msg, sub->external_name(), super->external_name(), linear_result, table_result);
1362 }
--- EOF ---