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 void Klass::initialize_preemptable(TRAPS) {
256 ShouldNotReachHere();
257 }
258
259 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
260 #ifdef ASSERT
261 tty->print_cr("Error: find_field called on a klass oop."
262 " Likely error: reflection method does not correctly"
263 " wrap return value in a mirror object.");
264 #endif
265 ShouldNotReachHere();
266 return nullptr;
267 }
268
269 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
270 OverpassLookupMode overpass_mode,
271 PrivateLookupMode private_mode) const {
272 #ifdef ASSERT
273 tty->print_cr("Error: uncached_lookup_method called on a klass oop."
274 " Likely error: reflection method does not correctly"
275 " wrap return value in a mirror object.");
276 #endif
277 ShouldNotReachHere();
278 return nullptr;
279 }
280
281 static markWord make_prototype(const Klass* kls) {
282 markWord prototype = markWord::prototype();
283 #ifdef _LP64
284 if (UseCompactObjectHeaders) {
285 // With compact object headers, the narrow Klass ID is part of the mark word.
286 // We therefore seed the mark word with the narrow Klass ID.
287 precond(CompressedKlassPointers::is_encodable(kls));
288 const narrowKlass nk = CompressedKlassPointers::encode(const_cast<Klass*>(kls));
289 prototype = prototype.set_narrow_klass(nk);
290 }
291 #endif
292 return prototype;
293 }
294
295 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
296 return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
297 }
298
299 Klass::Klass() : _kind(UnknownKlassKind) {
300 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
301 }
302
303 // "Normal" instantiation is preceded by a MetaspaceObj allocation
304 // which zeros out memory - calloc equivalent.
305 // The constructor is also used from CppVtableCloner,
306 // which doesn't zero out the memory before calling the constructor.
307 Klass::Klass(KlassKind kind) : _kind(kind),
308 _prototype_header(make_prototype(this)),
309 _shared_class_path_index(-1) {
310 CDS_ONLY(_aot_class_flags = 0;)
311 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
312 _primary_supers[0] = this;
313 set_super_check_offset(in_bytes(primary_supers_offset()));
314 }
315
316 jint Klass::array_layout_helper(BasicType etype) {
317 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
318 // Note that T_ARRAY is not allowed here.
319 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
320 int esize = type2aelembytes(etype);
321 bool isobj = (etype == T_OBJECT);
322 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
323 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
324
325 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
326 assert(layout_helper_is_array(lh), "correct kind");
327 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
328 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
329 assert(layout_helper_header_size(lh) == hsize, "correct decode");
330 assert(layout_helper_element_type(lh) == etype, "correct decode");
331 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
332
333 return lh;
334 }
335
336 int Klass::modifier_flags() const {
337 int mods = java_lang_Class::modifiers(java_mirror());
338 assert(mods == compute_modifier_flags(), "should be same");
339 return mods;
340 }
341
342 bool Klass::can_be_primary_super_slow() const {
343 if (super() == nullptr)
344 return true;
345 else if (super()->super_depth() >= primary_super_limit()-1)
346 return false;
347 else
348 return true;
349 }
350
351 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
352 #ifdef ASSERT
353 if (secondaries != nullptr) {
354 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
355 assert(bitmap == real_bitmap, "must be");
356 assert(secondaries->length() >= (int)population_count(bitmap), "must be");
357 }
358 #endif
359 _secondary_supers_bitmap = bitmap;
360 _secondary_supers = secondaries;
361
362 if (secondaries != nullptr) {
363 LogMessage(class, load) msg;
364 NonInterleavingLogStream log {LogLevel::Debug, msg};
365 if (log.is_enabled()) {
366 ResourceMark rm;
367 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
368 print_secondary_supers_on(&log);
369 }
370 }
371 }
372
373 // Hashed secondary superclasses
374 //
375 // We use a compressed 64-entry hash table with linear probing. We
376 // start by creating a hash table in the usual way, followed by a pass
377 // that removes all the null entries. To indicate which entries would
378 // have been null we use a bitmap that contains a 1 in each position
379 // where an entry is present, 0 otherwise. This bitmap also serves as
380 // a kind of Bloom filter, which in many cases allows us quickly to
381 // eliminate the possibility that something is a member of a set of
382 // secondaries.
383 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
384 const int length = secondaries->length();
385
386 if (length == 0) {
387 return SECONDARY_SUPERS_BITMAP_EMPTY;
388 }
389
390 if (length == 1) {
391 int hash_slot = secondaries->at(0)->hash_slot();
392 return uintx(1) << hash_slot;
393 }
394
395 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)
396
397 // Don't attempt to hash a table that's completely full, because in
398 // the case of an absent interface linear probing would not
399 // terminate.
400 if (length >= SECONDARY_SUPERS_TABLE_SIZE) {
401 return SECONDARY_SUPERS_BITMAP_FULL;
402 }
403
404 {
405 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time());
406
407 ResourceMark rm;
408 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
409 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
410 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
411
412 for (int j = 0; j < length; j++) {
413 Klass* k = secondaries->at(j);
414 hash_insert(k, hashed_secondaries, bitmap);
415 }
416
417 // Pack the hashed secondaries array by copying it into the
418 // secondaries array, sans nulls, if modification is allowed.
419 // Otherwise, validate the order.
420 int i = 0;
421 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
422 bool has_element = ((bitmap >> slot) & 1) != 0;
423 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
424 if (has_element) {
425 Klass* k = hashed_secondaries->at(slot);
426 if (rewrite) {
427 secondaries->at_put(i, k);
428 } else if (secondaries->at(i) != k) {
429 assert(false, "broken secondary supers hash table");
430 return SECONDARY_SUPERS_BITMAP_FULL;
431 }
432 i++;
433 }
434 }
435 assert(i == secondaries->length(), "mismatch");
436 postcond((int)population_count(bitmap) == secondaries->length());
437
438 return bitmap;
439 }
440 }
441
442 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
443 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
444
445 int dist = 0;
446 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
447 Klass* existing = secondaries->at(slot);
448 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
449 if (existing == nullptr) { // no conflict
450 secondaries->at_put(slot, klass);
451 bitmap |= uintx(1) << slot;
452 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
453 return;
454 } else {
455 // Use Robin Hood hashing to minimize the worst case search.
456 // Also, every permutation of the insertion sequence produces
457 // the same final Robin Hood hash table, provided that a
458 // consistent tie breaker is used.
459 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
460 if (existing_dist < dist
461 // This tie breaker ensures that the hash order is maintained.
462 || ((existing_dist == dist)
463 && (uintptr_t(existing) < uintptr_t(klass)))) {
464 Klass* tmp = secondaries->at(slot);
465 secondaries->at_put(slot, klass);
466 klass = tmp;
467 dist = existing_dist;
468 }
469 ++dist;
470 }
471 }
472 }
473
474 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
475 GrowableArray<Klass*>* primaries,
476 GrowableArray<Klass*>* secondaries,
477 uintx& bitmap, TRAPS) {
478 int new_length = primaries->length() + secondaries->length();
479 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
480
481 // Combine the two arrays into a metadata object to pack the array.
482 // The primaries are added in the reverse order, then the secondaries.
483 int fill_p = primaries->length();
484 for (int j = 0; j < fill_p; j++) {
485 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
486 }
487 for( int j = 0; j < secondaries->length(); j++ ) {
488 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
489 }
490 #ifdef ASSERT
491 // We must not copy any null placeholders left over from bootstrap.
492 for (int j = 0; j < secondary_supers->length(); j++) {
493 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
494 }
495 #endif
496
497 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
498 return secondary_supers;
499 }
500
501 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
502 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
503 }
504
505 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
506 uint8_t hash = k->hash_slot();
507 if (hash > 0) {
508 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
509 }
510 return 0;
511 }
512
513
514 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
515 if (k == nullptr) {
516 set_super(nullptr);
517 _primary_supers[0] = this;
518 assert(super_depth() == 0, "Object must already be initialized properly");
519 } else if (k != super() || k == vmClasses::Object_klass()) {
520 assert(super() == nullptr || super() == vmClasses::Object_klass(),
521 "initialize this only once to a non-trivial value");
522 set_super(k);
523 Klass* sup = k;
524 int sup_depth = sup->super_depth();
525 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
526 if (!can_be_primary_super_slow())
527 my_depth = primary_super_limit();
528 for (juint i = 0; i < my_depth; i++) {
529 _primary_supers[i] = sup->_primary_supers[i];
530 }
531 Klass* *super_check_cell;
532 if (my_depth < primary_super_limit()) {
533 _primary_supers[my_depth] = this;
534 super_check_cell = &_primary_supers[my_depth];
535 } else {
536 // Overflow of the primary_supers array forces me to be secondary.
537 super_check_cell = &_secondary_super_cache;
538 }
539 set_super_check_offset(u4((address)super_check_cell - (address) this));
540
541 #ifdef ASSERT
542 {
543 juint j = super_depth();
544 assert(j == my_depth, "computed accessor gets right answer");
545 Klass* t = this;
546 while (!t->can_be_primary_super()) {
547 t = t->super();
548 j = t->super_depth();
549 }
550 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
551 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
552 }
553 while (t != nullptr) {
554 assert(primary_super_of_depth(j) == t, "super list initialization");
555 t = t->super();
556 --j;
557 }
558 assert(j == (juint)-1, "correct depth count");
559 }
560 #endif
561 }
562
563 if (secondary_supers() == nullptr) {
564
565 // Now compute the list of secondary supertypes.
566 // Secondaries can occasionally be on the super chain,
567 // if the inline "_primary_supers" array overflows.
568 int extras = 0;
569 Klass* p;
570 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
571 ++extras;
572 }
573
574 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
575
576 // Compute the "real" non-extra secondaries.
577 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
578 if (secondaries == nullptr) {
579 // secondary_supers set by compute_secondary_supers
580 return;
581 }
582
583 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
584
585 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
586 int i; // Scan for overflow primaries being duplicates of 2nd'arys
587
588 // This happens frequently for very deeply nested arrays: the
589 // primary superclass chain overflows into the secondary. The
590 // secondary list contains the element_klass's secondaries with
591 // an extra array dimension added. If the element_klass's
592 // secondary list already contains some primary overflows, they
593 // (with the extra level of array-ness) will collide with the
594 // normal primary superclass overflows.
595 for( i = 0; i < secondaries->length(); i++ ) {
596 if( secondaries->at(i) == p )
597 break;
598 }
599 if( i < secondaries->length() )
600 continue; // It's a dup, don't put it in
601 primaries->push(p);
602 }
603 // Combine the two arrays into a metadata object to pack the array.
604 uintx bitmap = 0;
605 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
606 set_secondary_supers(s2, bitmap);
607 }
608 }
609
610 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
611 Array<InstanceKlass*>* transitive_interfaces) {
612 assert(num_extra_slots == 0, "override for complex klasses");
613 assert(transitive_interfaces == nullptr, "sanity");
614 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
615 return nullptr;
616 }
617
618
619 // subklass links. Used by the compiler (and vtable initialization)
620 // May be cleaned concurrently, so must use the Compile_lock.
621 Klass* Klass::subklass() const {
622 // Need load_acquire on the _subklass, because it races with inserts that
623 // publishes freshly initialized data.
624 for (Klass* chain = AtomicAccess::load_acquire(&_subklass);
625 chain != nullptr;
626 // Do not need load_acquire on _next_sibling, because inserts never
627 // create _next_sibling edges to dead data.
628 chain = AtomicAccess::load(&chain->_next_sibling))
629 {
630 if (chain->is_loader_alive()) {
631 return chain;
632 }
633 }
634 return nullptr;
635 }
636
637 Klass* Klass::next_sibling(bool log) const {
638 // Do not need load_acquire on _next_sibling, because inserts never
639 // create _next_sibling edges to dead data.
640 for (Klass* chain = AtomicAccess::load(&_next_sibling);
641 chain != nullptr;
642 chain = AtomicAccess::load(&chain->_next_sibling)) {
643 // Only return alive klass, there may be stale klass
644 // in this chain if cleaned concurrently.
645 if (chain->is_loader_alive()) {
646 return chain;
647 } else if (log) {
648 if (log_is_enabled(Trace, class, unload)) {
649 ResourceMark rm;
650 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
651 }
652 }
653 }
654 return nullptr;
655 }
656
657 void Klass::set_subklass(Klass* s) {
658 assert(s != this, "sanity check");
659 AtomicAccess::release_store(&_subklass, s);
660 }
661
662 void Klass::set_next_sibling(Klass* s) {
663 assert(s != this, "sanity check");
664 // Does not need release semantics. If used by cleanup, it will link to
665 // already safely published data, and if used by inserts, will be published
666 // safely using cmpxchg.
667 AtomicAccess::store(&_next_sibling, s);
668 }
669
670 void Klass::append_to_sibling_list() {
671 if (Universe::is_fully_initialized()) {
672 assert_locked_or_safepoint(Compile_lock);
673 }
674 DEBUG_ONLY(verify();)
675 // add ourselves to super' subklass list
676 InstanceKlass* super = java_super();
677 if (super == nullptr) return; // special case: class Object
678 assert((!super->is_interface() // interfaces cannot be supers
679 && (super->java_super() == nullptr || !is_interface())),
680 "an interface can only be a subklass of Object");
681
682 // Make sure there is no stale subklass head
683 super->clean_subklass();
684
685 for (;;) {
686 Klass* prev_first_subklass = AtomicAccess::load_acquire(&_super->_subklass);
687 if (prev_first_subklass != nullptr) {
688 // set our sibling to be the super' previous first subklass
689 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
690 set_next_sibling(prev_first_subklass);
691 }
692 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
693 // are ever created to not alive klasses. This is an important invariant of the lock-free
694 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
695 if (AtomicAccess::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
696 return;
697 }
698 }
699 DEBUG_ONLY(verify();)
700 }
701
702 // The log parameter is for clean_weak_klass_links to report unlinked classes.
703 Klass* Klass::clean_subklass(bool log) {
704 for (;;) {
705 // Need load_acquire, due to contending with concurrent inserts
706 Klass* subklass = AtomicAccess::load_acquire(&_subklass);
707 if (subklass == nullptr || subklass->is_loader_alive()) {
708 return subklass;
709 }
710 if (log && log_is_enabled(Trace, class, unload)) {
711 ResourceMark rm;
712 log_trace(class, unload)("unlinking class (subclass): %s", subklass->external_name());
713 }
714 // Try to fix _subklass until it points at something not dead.
715 AtomicAccess::cmpxchg(&_subklass, subklass, subklass->next_sibling(log));
716 }
717 }
718
719 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
720 if (!ClassUnloading || !unloading_occurred) {
721 return;
722 }
723
724 Klass* root = vmClasses::Object_klass();
725 Stack<Klass*, mtGC> stack;
726
727 stack.push(root);
728 while (!stack.is_empty()) {
729 Klass* current = stack.pop();
730
731 assert(current->is_loader_alive(), "just checking, this should be live");
732
733 // Find and set the first alive subklass
734 Klass* sub = current->clean_subklass(true);
735 if (sub != nullptr) {
736 stack.push(sub);
737 }
738
739 // Find and set the first alive sibling
740 Klass* sibling = current->next_sibling(true);
741 current->set_next_sibling(sibling);
742 if (sibling != nullptr) {
743 stack.push(sibling);
744 }
745
746 // Clean the implementors list and method data.
747 if (clean_alive_klasses && current->is_instance_klass()) {
748 InstanceKlass* ik = InstanceKlass::cast(current);
749 clean_weak_instanceklass_links(ik);
750 }
751 }
752 }
753
754 void Klass::clean_weak_instanceklass_links(InstanceKlass* ik) {
755 ik->clean_weak_instanceklass_links();
756 // JVMTI RedefineClasses creates previous versions that are not in
757 // the class hierarchy, so process them here.
758 while ((ik = ik->previous_versions()) != nullptr) {
759 ik->clean_weak_instanceklass_links();
760 }
761 }
762
763 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
764 if (log_is_enabled(Trace, aot)) {
765 ResourceMark rm;
766 log_trace(aot)("Iter(Klass): %p (%s)", this, external_name());
767 }
768
769 it->push(&_name);
770 it->push(&_secondary_supers);
771 for (int i = 0; i < _primary_super_limit; i++) {
772 it->push(&_primary_supers[i]);
773 }
774 it->push(&_super);
775 if (!CDSConfig::is_dumping_archive()) {
776 // If dumping archive, these may point to excluded classes. There's no need
777 // to follow these pointers anyway, as they will be set to null in
778 // remove_unshareable_info().
779 it->push((Klass**)&_subklass);
780 it->push((Klass**)&_next_sibling);
781 it->push(&_next_link);
782 }
783
784 vtableEntry* vt = start_of_vtable();
785 for (int i=0; i<vtable_length(); i++) {
786 it->push(vt[i].method_addr());
787 }
788 }
789
790 #if INCLUDE_CDS
791 void Klass::remove_unshareable_info() {
792 assert(CDSConfig::is_dumping_archive(),
793 "only called during CDS dump time");
794 JFR_ONLY(REMOVE_ID(this);)
795 if (log_is_enabled(Trace, aot, unshareable)) {
796 ResourceMark rm;
797 log_trace(aot, unshareable)("remove: %s", external_name());
798 }
799
800 // _secondary_super_cache may be updated by an is_subtype_of() call
801 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
802 // null and let it be repopulated at runtime.
803 set_secondary_super_cache(nullptr);
804
805 set_subklass(nullptr);
806 set_next_sibling(nullptr);
807 set_next_link(nullptr);
808
809 // Null out class_loader_data because we don't share that yet.
810 set_class_loader_data(nullptr);
811 set_in_aot_cache();
812
813 if (CDSConfig::is_dumping_classic_static_archive()) {
814 // "Classic" static archives are required to have deterministic contents.
815 // The elements in _secondary_supers are addresses in the ArchiveBuilder
816 // output buffer, so they should have deterministic values. If we rehash
817 // _secondary_supers, its elements will appear in a deterministic order.
818 //
819 // Note that the bitmap is guaranteed to be deterministic, regardless of the
820 // actual addresses of the elements in _secondary_supers. So rehashing shouldn't
821 // change it.
822 uintx bitmap = hash_secondary_supers(secondary_supers(), true);
823 assert(bitmap == _secondary_supers_bitmap, "bitmap should not be changed due to rehashing");
824 }
825 }
826
827 void Klass::remove_java_mirror() {
828 assert(CDSConfig::is_dumping_archive(), "sanity");
829 if (log_is_enabled(Trace, aot, unshareable)) {
830 ResourceMark rm;
831 log_trace(aot, unshareable)("remove java_mirror: %s", external_name());
832 }
833
834 #if INCLUDE_CDS_JAVA_HEAP
835 _archived_mirror_index = -1;
836 if (CDSConfig::is_dumping_heap()) {
837 Klass* src_k = ArchiveBuilder::current()->get_source_addr(this);
838 oop orig_mirror = src_k->java_mirror();
839 if (orig_mirror == nullptr) {
840 assert(CDSConfig::is_dumping_final_static_archive(), "sanity");
841 if (is_instance_klass()) {
842 assert(InstanceKlass::cast(this)->defined_by_other_loaders(), "sanity");
843 } else {
844 precond(is_objArray_klass());
845 Klass *k = ObjArrayKlass::cast(this)->bottom_klass();
846 precond(k->is_instance_klass());
847 assert(InstanceKlass::cast(k)->defined_by_other_loaders(), "sanity");
848 }
849 } else {
850 oop scratch_mirror = HeapShared::scratch_java_mirror(orig_mirror);
851 if (scratch_mirror != nullptr) {
852 _archived_mirror_index = HeapShared::append_root(scratch_mirror);
853 }
854 }
855 }
856 #endif
857
858 // Just null out the mirror. The class_loader_data() no longer exists.
859 clear_java_mirror_handle();
860 }
861
862 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
863 assert(is_klass(), "ensure C++ vtable is restored");
864 assert(in_aot_cache(), "must be set");
865 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be");
866 JFR_ONLY(RESTORE_ID(this);)
867 if (log_is_enabled(Trace, aot, unshareable)) {
868 ResourceMark rm(THREAD);
869 oop class_loader = loader_data->class_loader();
870 log_trace(aot, unshareable)("restore: %s with class loader: %s", external_name(),
871 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
872 }
873
874 // If an exception happened during CDS restore, some of these fields may already be
875 // set. We leave the class on the CLD list, even if incomplete so that we don't
876 // modify the CLD list outside a safepoint.
877 if (class_loader_data() == nullptr) {
878 set_class_loader_data(loader_data);
879
880 // Add to class loader list first before creating the mirror
881 // (same order as class file parsing)
882 loader_data->add_class(this);
883 }
884
885 Handle loader(THREAD, loader_data->class_loader());
886 ModuleEntry* module_entry = nullptr;
887 Klass* k = this;
888 if (k->is_objArray_klass()) {
889 k = ObjArrayKlass::cast(k)->bottom_klass();
890 }
891 // Obtain klass' module.
892 if (k->is_instance_klass()) {
893 InstanceKlass* ik = (InstanceKlass*) k;
894 module_entry = ik->module();
895 } else {
896 module_entry = ModuleEntryTable::javabase_moduleEntry();
897 }
898 // Obtain java.lang.Module, if available
899 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module_oop() : (oop)nullptr));
900
901 if (this->has_archived_mirror_index()) {
902 ResourceMark rm(THREAD);
903 log_debug(aot, mirror)("%s has raw archived mirror", external_name());
904 if (ArchiveHeapLoader::is_in_use()) {
905 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
906 protection_domain,
907 CHECK);
908 if (present) {
909 return;
910 }
911 }
912
913 // No archived mirror data
914 log_debug(aot, mirror)("No archived mirror data for %s", external_name());
915 clear_java_mirror_handle();
916 this->clear_archived_mirror_index();
917 }
918
919 // Only recreate it if not present. A previous attempt to restore may have
920 // gotten an OOM later but keep the mirror if it was created.
921 if (java_mirror() == nullptr) {
922 ResourceMark rm(THREAD);
923 log_trace(aot, mirror)("Recreate mirror for %s", external_name());
924 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
925 }
926 }
927 #endif // INCLUDE_CDS
928
929 #if INCLUDE_CDS_JAVA_HEAP
930 oop Klass::archived_java_mirror() {
931 assert(has_archived_mirror_index(), "must have archived mirror");
932 return HeapShared::get_root(_archived_mirror_index);
933 }
934
935 void Klass::clear_archived_mirror_index() {
936 if (_archived_mirror_index >= 0) {
937 HeapShared::clear_root(_archived_mirror_index);
938 }
939 _archived_mirror_index = -1;
940 }
941 #endif // INCLUDE_CDS_JAVA_HEAP
942
943 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
944 if (length > max_length) {
945 if (!THREAD->is_in_internal_oome_mark()) {
946 report_java_out_of_memory("Requested array size exceeds VM limit");
947 JvmtiExport::post_array_size_exhausted();
948 THROW_OOP(Universe::out_of_memory_error_array_size());
949 } else {
950 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
951 }
952 } else if (length < 0) {
953 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
954 }
955 }
956
957 // Replace the last '+' char with '/'.
958 static char* convert_hidden_name_to_java(Symbol* name) {
959 size_t name_len = name->utf8_length();
960 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
961 name->as_klass_external_name(result, (int)name_len + 1);
962 for (int index = (int)name_len; index > 0; index--) {
963 if (result[index] == '+') {
964 result[index] = JVM_SIGNATURE_SLASH;
965 break;
966 }
967 }
968 return result;
969 }
970
971 // In product mode, this function doesn't have virtual function calls so
972 // there might be some performance advantage to handling InstanceKlass here.
973 const char* Klass::external_name() const {
974 if (is_instance_klass()) {
975 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
976 if (ik->is_hidden()) {
977 char* result = convert_hidden_name_to_java(name());
978 return result;
979 }
980 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
981 char* result = convert_hidden_name_to_java(name());
982 return result;
983 }
984 if (name() == nullptr) return "<unknown>";
985 return name()->as_klass_external_name();
986 }
987
988 const char* Klass::signature_name() const {
989 if (name() == nullptr) return "<unknown>";
990 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
991 size_t name_len = name()->utf8_length();
992 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
993 name()->as_C_string(result, (int)name_len + 1);
994 for (int index = (int)name_len; index > 0; index--) {
995 if (result[index] == '+') {
996 result[index] = JVM_SIGNATURE_DOT;
997 break;
998 }
999 }
1000 return result;
1001 }
1002 return name()->as_C_string();
1003 }
1004
1005 const char* Klass::external_kind() const {
1006 if (is_interface()) return "interface";
1007 if (is_abstract()) return "abstract class";
1008 return "class";
1009 }
1010
1011 // Unless overridden, jvmti_class_status has no flags set.
1012 jint Klass::jvmti_class_status() const {
1013 return 0;
1014 }
1015
1016
1017 // Printing
1018
1019 void Klass::print_on(outputStream* st) const {
1020 ResourceMark rm;
1021 // print title
1022 st->print("%s", internal_name());
1023 print_address_on(st);
1024 st->cr();
1025 }
1026
1027 #define BULLET " - "
1028
1029 // Caller needs ResourceMark
1030 void Klass::oop_print_on(oop obj, outputStream* st) {
1031 // print title
1032 st->print_cr("%s ", internal_name());
1033 obj->print_address_on(st);
1034
1035 if (WizardMode) {
1036 // print header
1037 obj->mark().print_on(st);
1038 st->cr();
1039 if (UseCompactObjectHeaders) {
1040 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
1041 st->cr();
1042 }
1043 }
1044
1045 // print class
1046 st->print(BULLET"klass: ");
1047 obj->klass()->print_value_on(st);
1048 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr();
1049 st->cr();
1050 }
1051
1052 void Klass::oop_print_value_on(oop obj, outputStream* st) {
1053 // print title
1054 ResourceMark rm; // Cannot print in debug mode without this
1055 st->print("%s", internal_name());
1056 obj->print_address_on(st);
1057 }
1058
1059 // Verification
1060
1061 void Klass::verify_on(outputStream* st) {
1062
1063 // This can be expensive, but it is worth checking that this klass is actually
1064 // in the CLD graph but not in production.
1065 #ifdef ASSERT
1066 if (UseCompressedClassPointers) {
1067 // Stricter checks for both correct alignment and placement
1068 CompressedKlassPointers::check_encodable(this);
1069 } else {
1070 assert(Metaspace::contains((address)this), "Should be");
1071 }
1072 #endif // ASSERT
1073
1074 guarantee(this->is_klass(),"should be klass");
1075
1076 if (super() != nullptr) {
1077 guarantee(super()->is_klass(), "should be klass");
1078 }
1079 if (secondary_super_cache() != nullptr) {
1080 Klass* ko = secondary_super_cache();
1081 guarantee(ko->is_klass(), "should be klass");
1082 }
1083 for ( uint i = 0; i < primary_super_limit(); i++ ) {
1084 Klass* ko = _primary_supers[i];
1085 if (ko != nullptr) {
1086 guarantee(ko->is_klass(), "should be klass");
1087 }
1088 }
1089
1090 if (java_mirror_no_keepalive() != nullptr) {
1091 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
1092 }
1093 }
1094
1095 void Klass::oop_verify_on(oop obj, outputStream* st) {
1096 guarantee(oopDesc::is_oop(obj), "should be oop");
1097 guarantee(obj->klass()->is_klass(), "klass field is not a klass");
1098 }
1099
1100 // Note: this function is called with an address that may or may not be a Klass.
1101 // The point is not to assert it is but to check if it could be.
1102 bool Klass::is_valid(Klass* k) {
1103 if (!is_aligned(k, sizeof(MetaWord))) return false;
1104 if ((size_t)k < os::min_page_size()) return false;
1105
1106 if (!os::is_readable_range(k, k + 1)) return false;
1107 if (!Metaspace::contains(k)) return false;
1108
1109 if (!Symbol::is_valid(k->name())) return false;
1110 return ClassLoaderDataGraph::is_valid(k->class_loader_data());
1111 }
1112
1113 Method* Klass::method_at_vtable(int index) {
1114 #ifndef PRODUCT
1115 assert(index >= 0, "valid vtable index");
1116 if (DebugVtables) {
1117 verify_vtable_index(index);
1118 }
1119 #endif
1120 return start_of_vtable()[index].method();
1121 }
1122
1123
1124 #ifndef PRODUCT
1125
1126 bool Klass::verify_vtable_index(int i) {
1127 int limit = vtable_length()/vtableEntry::size();
1128 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
1129 return true;
1130 }
1131
1132 #endif // PRODUCT
1133
1134 // Caller needs ResourceMark
1135 // joint_in_module_of_loader provides an optimization if 2 classes are in
1136 // the same module to succinctly print out relevant information about their
1137 // module name and class loader's name_and_id for error messages.
1138 // Format:
1139 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
1140 // are in module <module-name>[@<version>]
1141 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1142 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
1143 assert(module() == class2->module(), "classes do not have the same module");
1144 const char* class1_name = external_name();
1145 size_t len = strlen(class1_name) + 1;
1146
1147 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
1148 len += strlen(class2_description);
1149
1150 len += strlen(" and ");
1151
1152 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1153
1154 // Just return the FQN if error when allocating string
1155 if (joint_description == nullptr) {
1156 return class1_name;
1157 }
1158
1159 jio_snprintf(joint_description, len, "%s and %s",
1160 class1_name,
1161 class2_description);
1162
1163 return joint_description;
1164 }
1165
1166 // Caller needs ResourceMark
1167 // class_in_module_of_loader provides a standard way to include
1168 // relevant information about a class, such as its module name as
1169 // well as its class loader's name_and_id, in error messages and logging.
1170 // Format:
1171 // <fully-qualified-external-class-name> is in module <module-name>[@<version>]
1172 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1173 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
1174 // 1. fully qualified external name of class
1175 const char* klass_name = external_name();
1176 size_t len = strlen(klass_name) + 1;
1177
1178 // 2. module name + @version
1179 const char* module_name = "";
1180 const char* version = "";
1181 bool has_version = false;
1182 bool module_is_named = false;
1183 const char* module_name_phrase = "";
1184 const Klass* bottom_klass = is_objArray_klass() ?
1185 ObjArrayKlass::cast(this)->bottom_klass() : this;
1186 if (bottom_klass->is_instance_klass()) {
1187 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
1188 if (module->is_named()) {
1189 module_is_named = true;
1190 module_name_phrase = "module ";
1191 module_name = module->name()->as_C_string();
1192 len += strlen(module_name);
1193 // Use version if exists and is not a jdk module
1194 if (module->should_show_version()) {
1195 has_version = true;
1196 version = module->version()->as_C_string();
1197 // Include stlen(version) + 1 for the "@"
1198 len += strlen(version) + 1;
1199 }
1200 } else {
1201 module_name = UNNAMED_MODULE;
1202 len += UNNAMED_MODULE_LEN;
1203 }
1204 } else {
1205 // klass is an array of primitives, module is java.base
1206 module_is_named = true;
1207 module_name_phrase = "module ";
1208 module_name = JAVA_BASE_NAME;
1209 len += JAVA_BASE_NAME_LEN;
1210 }
1211
1212 // 3. class loader's name_and_id
1213 ClassLoaderData* cld = class_loader_data();
1214 assert(cld != nullptr, "class_loader_data should not be null");
1215 const char* loader_name_and_id = cld->loader_name_and_id();
1216 len += strlen(loader_name_and_id);
1217
1218 // 4. include parent loader information
1219 const char* parent_loader_phrase = "";
1220 const char* parent_loader_name_and_id = "";
1221 if (include_parent_loader &&
1222 !cld->is_builtin_class_loader_data()) {
1223 oop parent_loader = java_lang_ClassLoader::parent(class_loader());
1224 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
1225 // The parent loader's ClassLoaderData could be null if it is
1226 // a delegating class loader that has never defined a class.
1227 // In this case the loader's name must be obtained via the parent loader's oop.
1228 if (parent_cld == nullptr) {
1229 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
1230 if (cl_name_and_id != nullptr) {
1231 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
1232 }
1233 } else {
1234 parent_loader_name_and_id = parent_cld->loader_name_and_id();
1235 }
1236 parent_loader_phrase = ", parent loader ";
1237 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
1238 }
1239
1240 // Start to construct final full class description string
1241 len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
1242 len += strlen(module_name_phrase) + strlen(" of loader ");
1243
1244 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1245
1246 // Just return the FQN if error when allocating string
1247 if (class_description == nullptr) {
1248 return klass_name;
1249 }
1250
1251 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
1252 klass_name,
1253 (use_are) ? "are" : "is",
1254 module_name_phrase,
1255 module_name,
1256 (has_version) ? "@" : "",
1257 (has_version) ? version : "",
1258 loader_name_and_id,
1259 parent_loader_phrase,
1260 parent_loader_name_and_id);
1261
1262 return class_description;
1263 }
1264
1265 class LookupStats : StackObj {
1266 private:
1267 uint _no_of_samples;
1268 uint _worst;
1269 uint _worst_count;
1270 uint _average;
1271 uint _best;
1272 uint _best_count;
1273 public:
1274 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {}
1275
1276 ~LookupStats() {
1277 assert(_best <= _worst || _no_of_samples == 0, "sanity");
1278 }
1279
1280 void sample(uint value) {
1281 ++_no_of_samples;
1282 _average += value;
1283
1284 if (_worst < value) {
1285 _worst = value;
1286 _worst_count = 1;
1287 } else if (_worst == value) {
1288 ++_worst_count;
1289 }
1290
1291 if (_best > value) {
1292 _best = value;
1293 _best_count = 1;
1294 } else if (_best == value) {
1295 ++_best_count;
1296 }
1297 }
1298
1299 void print_on(outputStream* st) const {
1300 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples);
1301 if (_best_count < _no_of_samples) {
1302 st->print("; average: %4.1f; worst: %2d (%4.1f%%)",
1303 (1.0 * _average) / _no_of_samples,
1304 _worst, (100.0 * _worst_count) / _no_of_samples);
1305 }
1306 }
1307 };
1308
1309 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) {
1310 int num_of_supers = secondary_supers->length();
1311
1312 LookupStats s;
1313 for (int i = 0; i < num_of_supers; i++) {
1314 Klass* secondary_super = secondary_supers->at(i);
1315 int home_slot = Klass::compute_home_slot(secondary_super, bitmap);
1316 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK);
1317 s.sample(score);
1318 }
1319 st->print("positive_lookup: "); s.print_on(st);
1320 }
1321
1322 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) {
1323 assert(~bitmap != 0, "no zeroes");
1324 uintx start = rotate_right(bitmap, slot);
1325 return count_trailing_zeros(~start);
1326 }
1327
1328 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) {
1329 LookupStats s;
1330 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
1331 uint score = compute_distance_to_nearest_zero(slot, bitmap);
1332 s.sample(score);
1333 }
1334 st->print("negative_lookup: "); s.print_on(st);
1335 }
1336
1337 void Klass::print_secondary_supers_on(outputStream* st) const {
1338 if (secondary_supers() != nullptr) {
1339 st->print(" - "); st->print("%d elements;", _secondary_supers->length());
1340 st->print_cr(" bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap);
1341 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY &&
1342 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) {
1343 st->print(" - "); print_positive_lookup_stats(secondary_supers(),
1344 _secondary_supers_bitmap, st); st->cr();
1345 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr();
1346 }
1347 } else {
1348 st->print("null");
1349 }
1350 }
1351
1352 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) {
1353 ResourceMark rm;
1354 super->print();
1355 sub->print();
1356 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d",
1357 msg, sub->external_name(), super->external_name(), linear_result, table_result);
1358 }