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