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