1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/archiveHeapLoader.hpp"
27 #include "cds/cdsConfig.hpp"
28 #include "cds/heapShared.hpp"
29 #include "classfile/classLoader.hpp"
30 #include "classfile/classLoaderData.inline.hpp"
31 #include "classfile/classLoaderDataGraph.inline.hpp"
32 #include "classfile/javaClasses.inline.hpp"
33 #include "classfile/moduleEntry.hpp"
34 #include "classfile/systemDictionary.hpp"
35 #include "classfile/systemDictionaryShared.hpp"
36 #include "classfile/vmClasses.hpp"
37 #include "classfile/vmSymbols.hpp"
38 #include "gc/shared/collectedHeap.inline.hpp"
39 #include "jvm_io.h"
40 #include "logging/log.hpp"
41 #include "memory/metadataFactory.hpp"
42 #include "memory/metaspaceClosure.hpp"
43 #include "memory/oopFactory.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "memory/universe.hpp"
46 #include "oops/compressedOops.inline.hpp"
47 #include "oops/instanceKlass.hpp"
48 #include "oops/klass.inline.hpp"
49 #include "oops/objArrayKlass.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/oopHandle.inline.hpp"
52 #include "prims/jvmtiExport.hpp"
53 #include "runtime/atomic.hpp"
54 #include "runtime/handles.inline.hpp"
55 #include "runtime/perfData.hpp"
56 #include "utilities/macros.hpp"
57 #include "utilities/powerOfTwo.hpp"
58 #include "utilities/rotate_bits.hpp"
59 #include "utilities/stack.inline.hpp"
60
61 void Klass::set_java_mirror(Handle m) {
62 assert(!m.is_null(), "New mirror should never be null.");
63 assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
64 _java_mirror = class_loader_data()->add_handle(m);
65 }
66
67 bool Klass::is_cloneable() const {
68 return _misc_flags.is_cloneable_fast() ||
69 is_subtype_of(vmClasses::Cloneable_klass());
70 }
71
72 void Klass::set_is_cloneable() {
73 if (name() == vmSymbols::java_lang_invoke_MemberName()) {
74 assert(is_final(), "no subclasses allowed");
75 // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
76 } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
77 // Reference cloning should not be intrinsified and always happen in JVM_Clone.
78 } else {
79 _misc_flags.set_is_cloneable_fast(true);
80 }
81 }
82
83 uint8_t Klass::compute_hash_slot(Symbol* n) {
84 uint hash_code;
85 // Special cases for the two superclasses of all Array instances.
86 // Code elsewhere assumes, for all instances of ArrayKlass, that
87 // these two interfaces will be in this order.
88
89 // We ensure there are some empty slots in the hash table between
90 // these two very common interfaces because if they were adjacent
91 // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1
92 // would result in a probe length of 3.
93 if (n == vmSymbols::java_lang_Cloneable()) {
94 hash_code = 0;
95 } else if (n == vmSymbols::java_io_Serializable()) {
96 hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2;
97 } else {
98 auto s = (const jbyte*) n->bytes();
99 hash_code = java_lang_String::hash_code(s, n->utf8_length());
100 // We use String::hash_code here (rather than e.g.
101 // Symbol::identity_hash()) in order to have a hash code that
102 // does not change from run to run. We want that because the
103 // hash value for a secondary superclass appears in generated
104 // code as a constant.
105
106 // This constant is magic: see Knuth, "Fibonacci Hashing".
107 constexpr uint multiplier
108 = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 ))
109 constexpr uint hash_shift = sizeof(hash_code) * 8 - 6;
110 // The leading bits of the least significant half of the product.
111 hash_code = (hash_code * multiplier) >> hash_shift;
112
113 if (StressSecondarySupers) {
114 // Generate many hash collisions in order to stress-test the
115 // linear search fallback.
116 hash_code = hash_code % 3;
117 hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3);
118 }
119 }
120
121 return (hash_code & SECONDARY_SUPERS_TABLE_MASK);
122 }
123
124 void Klass::set_name(Symbol* n) {
125 _name = n;
126
127 if (_name != nullptr) {
128 _name->increment_refcount();
129 }
130
131 {
132 elapsedTimer selftime;
133 selftime.start();
134
135 _hash_slot = compute_hash_slot(n);
136 assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required");
137
138 selftime.stop();
139 if (UsePerfData) {
140 ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks());
141 }
142 }
143
144 if (CDSConfig::is_dumping_archive() && is_instance_klass()) {
145 SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
146 }
147 }
148
149 bool Klass::is_subclass_of(const Klass* k) const {
150 // Run up the super chain and check
151 if (this == k) return true;
152
153 Klass* t = const_cast<Klass*>(this)->super();
154
155 while (t != nullptr) {
156 if (t == k) return true;
157 t = t->super();
158 }
159 return false;
160 }
161
162 void Klass::release_C_heap_structures(bool release_constant_pool) {
163 if (_name != nullptr) _name->decrement_refcount();
164 }
165
166 bool Klass::linear_search_secondary_supers(const Klass* k) const {
167 // Scan the array-of-objects for a match
168 // FIXME: We could do something smarter here, maybe a vectorized
169 // comparison or a binary search, but is that worth any added
170 // complexity?
171 int cnt = secondary_supers()->length();
172 for (int i = 0; i < cnt; i++) {
173 if (secondary_supers()->at(i) == k) {
174 return true;
175 }
176 }
177 return false;
178 }
179
180 // Given a secondary superklass k, an initial array index, and an
181 // occupancy bitmap rotated such that Bit 1 is the next bit to test,
182 // search for k.
183 bool Klass::fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const {
184 // Once the occupancy bitmap is almost full, it's faster to use a
185 // linear search.
186 if (secondary_supers()->length() > SECONDARY_SUPERS_TABLE_SIZE - 2) {
187 return linear_search_secondary_supers(k);
188 }
189
190 // This is conventional linear probing, but instead of terminating
191 // when a null entry is found in the table, we maintain a bitmap
192 // in which a 0 indicates missing entries.
193
194 precond((int)population_count(rotated_bitmap) == secondary_supers()->length());
195
196 // The check for secondary_supers()->length() <= SECONDARY_SUPERS_TABLE_SIZE - 2
197 // at the start of this function guarantees there are 0s in the
198 // bitmap, so this loop eventually terminates.
199 while ((rotated_bitmap & 2) != 0) {
200 if (++index == secondary_supers()->length()) {
201 index = 0;
202 }
203 if (secondary_supers()->at(index) == k) {
204 return true;
205 }
206 rotated_bitmap = rotate_right(rotated_bitmap, 1);
207 }
208 return false;
209 }
210
211 // Return self, except for abstract classes with exactly 1
212 // implementor. Then return the 1 concrete implementation.
213 Klass *Klass::up_cast_abstract() {
214 Klass *r = this;
215 while( r->is_abstract() ) { // Receiver is abstract?
216 Klass *s = r->subklass(); // Check for exactly 1 subklass
217 if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up
218 return this; // Return 'this' as a no-progress flag
219 r = s; // Loop till find concrete class
220 }
221 return r; // Return the 1 concrete class
222 }
223
224 // Find LCA in class hierarchy
225 Klass *Klass::LCA( Klass *k2 ) {
226 Klass *k1 = this;
227 while( 1 ) {
228 if( k1->is_subtype_of(k2) ) return k2;
229 if( k2->is_subtype_of(k1) ) return k1;
230 k1 = k1->super();
231 k2 = k2->super();
232 }
233 }
234
235
236 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
237 ResourceMark rm(THREAD);
238 THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
239 : vmSymbols::java_lang_InstantiationException(), external_name());
240 }
241
242
243 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
244 ResourceMark rm(THREAD);
245 assert(s != nullptr, "Throw NPE!");
246 THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
247 err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
248 }
249
250
251 void Klass::initialize(TRAPS) {
252 ShouldNotReachHere();
253 }
254
255 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
256 #ifdef ASSERT
257 tty->print_cr("Error: find_field called on a klass oop."
258 " Likely error: reflection method does not correctly"
259 " wrap return value in a mirror object.");
260 #endif
261 ShouldNotReachHere();
262 return nullptr;
263 }
264
265 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
266 OverpassLookupMode overpass_mode,
267 PrivateLookupMode private_mode) const {
268 #ifdef ASSERT
269 tty->print_cr("Error: uncached_lookup_method called on a klass oop."
270 " Likely error: reflection method does not correctly"
271 " wrap return value in a mirror object.");
272 #endif
273 ShouldNotReachHere();
274 return nullptr;
275 }
276
277 Klass::Klass() : _kind(UnknownKlassKind) {
278 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
279 }
280
281 // "Normal" instantiation is preceded by a MetaspaceObj allocation
282 // which zeros out memory - calloc equivalent.
283 // The constructor is also used from CppVtableCloner,
284 // which doesn't zero out the memory before calling the constructor.
285 Klass::Klass(KlassKind kind) : _kind(kind),
286 _shared_class_path_index(-1) {
287 CDS_ONLY(_shared_class_flags = 0;)
288 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
289 _primary_supers[0] = this;
290 set_super_check_offset(in_bytes(primary_supers_offset()));
291 }
292
293 jint Klass::array_layout_helper(BasicType etype) {
294 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
295 // Note that T_ARRAY is not allowed here.
296 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
297 int esize = type2aelembytes(etype);
298 bool isobj = (etype == T_OBJECT);
299 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
300 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
301
302 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
303 assert(layout_helper_is_array(lh), "correct kind");
304 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
305 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
306 assert(layout_helper_header_size(lh) == hsize, "correct decode");
307 assert(layout_helper_element_type(lh) == etype, "correct decode");
308 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
309
310 return lh;
311 }
312
313 bool Klass::can_be_primary_super_slow() const {
314 if (super() == nullptr)
315 return true;
316 else if (super()->super_depth() >= primary_super_limit()-1)
317 return false;
318 else
319 return true;
320 }
321
322 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
323 #ifdef ASSERT
324 if (secondaries != nullptr) {
325 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
326 assert(bitmap == real_bitmap, "must be");
327 assert(secondaries->length() >= (int)population_count(bitmap), "must be");
328 }
329 #endif
330 _secondary_supers_bitmap = bitmap;
331 _secondary_supers = secondaries;
332
333 if (secondaries != nullptr) {
334 LogMessage(class, load) msg;
335 NonInterleavingLogStream log {LogLevel::Debug, msg};
336 if (log.is_enabled()) {
337 ResourceMark rm;
338 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
339 print_secondary_supers_on(&log);
340 }
341 }
342 }
343
344 // Hashed secondary superclasses
345 //
346 // We use a compressed 64-entry hash table with linear probing. We
347 // start by creating a hash table in the usual way, followed by a pass
348 // that removes all the null entries. To indicate which entries would
349 // have been null we use a bitmap that contains a 1 in each position
350 // where an entry is present, 0 otherwise. This bitmap also serves as
351 // a kind of Bloom filter, which in many cases allows us quickly to
352 // eliminate the possibility that something is a member of a set of
353 // secondaries.
354 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
355 const int length = secondaries->length();
356
357 if (length == 0) {
358 return SECONDARY_SUPERS_BITMAP_EMPTY;
359 }
360
361 if (length == 1) {
362 int hash_slot = secondaries->at(0)->hash_slot();
363 return uintx(1) << hash_slot;
364 }
365
366 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)
367
368 // Don't attempt to hash a table that's completely full, because in
369 // the case of an absent interface linear probing would not
370 // terminate.
371 if (length >= SECONDARY_SUPERS_TABLE_SIZE) {
372 return SECONDARY_SUPERS_BITMAP_FULL;
373 }
374
375 {
376 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time());
377
378 ResourceMark rm;
379 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
380 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
381 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
382
383 for (int j = 0; j < length; j++) {
384 Klass* k = secondaries->at(j);
385 hash_insert(k, hashed_secondaries, bitmap);
386 }
387
388 // Pack the hashed secondaries array by copying it into the
389 // secondaries array, sans nulls, if modification is allowed.
390 // Otherwise, validate the order.
391 int i = 0;
392 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
393 bool has_element = ((bitmap >> slot) & 1) != 0;
394 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
395 if (has_element) {
396 Klass* k = hashed_secondaries->at(slot);
397 if (rewrite) {
398 secondaries->at_put(i, k);
399 } else if (secondaries->at(i) != k) {
400 assert(false, "broken secondary supers hash table");
401 return SECONDARY_SUPERS_BITMAP_FULL;
402 }
403 i++;
404 }
405 }
406 assert(i == secondaries->length(), "mismatch");
407 postcond((int)population_count(bitmap) == secondaries->length());
408
409 return bitmap;
410 }
411 }
412
413 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
414 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
415
416 int dist = 0;
417 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
418 Klass* existing = secondaries->at(slot);
419 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
420 if (existing == nullptr) { // no conflict
421 secondaries->at_put(slot, klass);
422 bitmap |= uintx(1) << slot;
423 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
424 return;
425 } else {
426 // Use Robin Hood hashing to minimize the worst case search.
427 // Also, every permutation of the insertion sequence produces
428 // the same final Robin Hood hash table, provided that a
429 // consistent tie breaker is used.
430 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
431 if (existing_dist < dist
432 // This tie breaker ensures that the hash order is maintained.
433 || ((existing_dist == dist)
434 && (uintptr_t(existing) < uintptr_t(klass)))) {
435 Klass* tmp = secondaries->at(slot);
436 secondaries->at_put(slot, klass);
437 klass = tmp;
438 dist = existing_dist;
439 }
440 ++dist;
441 }
442 }
443 }
444
445 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
446 GrowableArray<Klass*>* primaries,
447 GrowableArray<Klass*>* secondaries,
448 uintx& bitmap, TRAPS) {
449 int new_length = primaries->length() + secondaries->length();
450 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
451
452 // Combine the two arrays into a metadata object to pack the array.
453 // The primaries are added in the reverse order, then the secondaries.
454 int fill_p = primaries->length();
455 for (int j = 0; j < fill_p; j++) {
456 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
457 }
458 for( int j = 0; j < secondaries->length(); j++ ) {
459 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
460 }
461 #ifdef ASSERT
462 // We must not copy any null placeholders left over from bootstrap.
463 for (int j = 0; j < secondary_supers->length(); j++) {
464 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
465 }
466 #endif
467
468 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
469 return secondary_supers;
470 }
471
472 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
473 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
474 }
475
476 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
477 uint8_t hash = k->hash_slot();
478 if (hash > 0) {
479 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
480 }
481 return 0;
482 }
483
484
485 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
486 if (k == nullptr) {
487 set_super(nullptr);
488 _primary_supers[0] = this;
489 assert(super_depth() == 0, "Object must already be initialized properly");
490 } else if (k != super() || k == vmClasses::Object_klass()) {
491 assert(super() == nullptr || super() == vmClasses::Object_klass(),
492 "initialize this only once to a non-trivial value");
493 set_super(k);
494 Klass* sup = k;
495 int sup_depth = sup->super_depth();
496 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
497 if (!can_be_primary_super_slow())
498 my_depth = primary_super_limit();
499 for (juint i = 0; i < my_depth; i++) {
500 _primary_supers[i] = sup->_primary_supers[i];
501 }
502 Klass* *super_check_cell;
503 if (my_depth < primary_super_limit()) {
504 _primary_supers[my_depth] = this;
505 super_check_cell = &_primary_supers[my_depth];
506 } else {
507 // Overflow of the primary_supers array forces me to be secondary.
508 super_check_cell = &_secondary_super_cache;
509 }
510 set_super_check_offset(u4((address)super_check_cell - (address) this));
511
512 #ifdef ASSERT
513 {
514 juint j = super_depth();
515 assert(j == my_depth, "computed accessor gets right answer");
516 Klass* t = this;
517 while (!t->can_be_primary_super()) {
518 t = t->super();
519 j = t->super_depth();
520 }
521 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
522 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
523 }
524 while (t != nullptr) {
525 assert(primary_super_of_depth(j) == t, "super list initialization");
526 t = t->super();
527 --j;
528 }
529 assert(j == (juint)-1, "correct depth count");
530 }
531 #endif
532 }
533
534 if (secondary_supers() == nullptr) {
535
536 // Now compute the list of secondary supertypes.
537 // Secondaries can occasionally be on the super chain,
538 // if the inline "_primary_supers" array overflows.
539 int extras = 0;
540 Klass* p;
541 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
542 ++extras;
543 }
544
545 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
546
547 // Compute the "real" non-extra secondaries.
548 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
549 if (secondaries == nullptr) {
550 // secondary_supers set by compute_secondary_supers
551 return;
552 }
553
554 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
555
556 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
557 int i; // Scan for overflow primaries being duplicates of 2nd'arys
558
559 // This happens frequently for very deeply nested arrays: the
560 // primary superclass chain overflows into the secondary. The
561 // secondary list contains the element_klass's secondaries with
562 // an extra array dimension added. If the element_klass's
563 // secondary list already contains some primary overflows, they
564 // (with the extra level of array-ness) will collide with the
565 // normal primary superclass overflows.
566 for( i = 0; i < secondaries->length(); i++ ) {
567 if( secondaries->at(i) == p )
568 break;
569 }
570 if( i < secondaries->length() )
571 continue; // It's a dup, don't put it in
572 primaries->push(p);
573 }
574 // Combine the two arrays into a metadata object to pack the array.
575 uintx bitmap = 0;
576 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
577 set_secondary_supers(s2, bitmap);
578 }
579 }
580
581 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
582 Array<InstanceKlass*>* transitive_interfaces) {
583 assert(num_extra_slots == 0, "override for complex klasses");
584 assert(transitive_interfaces == nullptr, "sanity");
585 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
586 return nullptr;
587 }
588
589
590 // superklass links
591 InstanceKlass* Klass::superklass() const {
592 assert(super() == nullptr || super()->is_instance_klass(), "must be instance klass");
593 return _super == nullptr ? nullptr : InstanceKlass::cast(_super);
594 }
595
596 // subklass links. Used by the compiler (and vtable initialization)
597 // May be cleaned concurrently, so must use the Compile_lock.
598 // The log parameter is for clean_weak_klass_links to report unlinked classes.
599 Klass* Klass::subklass(bool log) const {
600 // Need load_acquire on the _subklass, because it races with inserts that
601 // publishes freshly initialized data.
602 for (Klass* chain = Atomic::load_acquire(&_subklass);
603 chain != nullptr;
604 // Do not need load_acquire on _next_sibling, because inserts never
605 // create _next_sibling edges to dead data.
606 chain = Atomic::load(&chain->_next_sibling))
607 {
608 if (chain->is_loader_alive()) {
609 return chain;
610 } else if (log) {
611 if (log_is_enabled(Trace, class, unload)) {
612 ResourceMark rm;
613 log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
614 }
615 }
616 }
617 return nullptr;
618 }
619
620 Klass* Klass::next_sibling(bool log) const {
621 // Do not need load_acquire on _next_sibling, because inserts never
622 // create _next_sibling edges to dead data.
623 for (Klass* chain = Atomic::load(&_next_sibling);
624 chain != nullptr;
625 chain = Atomic::load(&chain->_next_sibling)) {
626 // Only return alive klass, there may be stale klass
627 // in this chain if cleaned concurrently.
628 if (chain->is_loader_alive()) {
629 return chain;
630 } else if (log) {
631 if (log_is_enabled(Trace, class, unload)) {
632 ResourceMark rm;
633 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
634 }
635 }
636 }
637 return nullptr;
638 }
639
640 void Klass::set_subklass(Klass* s) {
641 assert(s != this, "sanity check");
642 Atomic::release_store(&_subklass, s);
643 }
644
645 void Klass::set_next_sibling(Klass* s) {
646 assert(s != this, "sanity check");
647 // Does not need release semantics. If used by cleanup, it will link to
648 // already safely published data, and if used by inserts, will be published
649 // safely using cmpxchg.
650 Atomic::store(&_next_sibling, s);
651 }
652
653 void Klass::append_to_sibling_list() {
654 if (Universe::is_fully_initialized()) {
655 assert_locked_or_safepoint(Compile_lock);
656 }
657 debug_only(verify();)
658 // add ourselves to superklass' subklass list
659 InstanceKlass* super = superklass();
660 if (super == nullptr) return; // special case: class Object
661 assert((!super->is_interface() // interfaces cannot be supers
662 && (super->superklass() == nullptr || !is_interface())),
663 "an interface can only be a subklass of Object");
664
665 // Make sure there is no stale subklass head
666 super->clean_subklass();
667
668 for (;;) {
669 Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
670 if (prev_first_subklass != nullptr) {
671 // set our sibling to be the superklass' previous first subklass
672 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
673 set_next_sibling(prev_first_subklass);
674 }
675 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
676 // are ever created to not alive klasses. This is an important invariant of the lock-free
677 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
678 if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
679 return;
680 }
681 }
682 debug_only(verify();)
683 }
684
685 void Klass::clean_subklass() {
686 for (;;) {
687 // Need load_acquire, due to contending with concurrent inserts
688 Klass* subklass = Atomic::load_acquire(&_subklass);
689 if (subklass == nullptr || subklass->is_loader_alive()) {
690 return;
691 }
692 // Try to fix _subklass until it points at something not dead.
693 Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
694 }
695 }
696
697 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
698 if (!ClassUnloading || !unloading_occurred) {
699 return;
700 }
701
702 Klass* root = vmClasses::Object_klass();
703 Stack<Klass*, mtGC> stack;
704
705 stack.push(root);
706 while (!stack.is_empty()) {
707 Klass* current = stack.pop();
708
709 assert(current->is_loader_alive(), "just checking, this should be live");
710
711 // Find and set the first alive subklass
712 Klass* sub = current->subklass(true);
713 current->clean_subklass();
714 if (sub != nullptr) {
715 stack.push(sub);
716 }
717
718 // Find and set the first alive sibling
719 Klass* sibling = current->next_sibling(true);
720 current->set_next_sibling(sibling);
721 if (sibling != nullptr) {
722 stack.push(sibling);
723 }
724
725 // Clean the implementors list and method data.
726 if (clean_alive_klasses && current->is_instance_klass()) {
727 InstanceKlass* ik = InstanceKlass::cast(current);
728 ik->clean_weak_instanceklass_links();
729
730 // JVMTI RedefineClasses creates previous versions that are not in
731 // the class hierarchy, so process them here.
732 while ((ik = ik->previous_versions()) != nullptr) {
733 ik->clean_weak_instanceklass_links();
734 }
735 }
736 }
737 }
738
739 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
740 if (log_is_enabled(Trace, cds)) {
741 ResourceMark rm;
742 log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
743 }
744
745 it->push(&_name);
746 it->push(&_secondary_supers);
747 for (int i = 0; i < _primary_super_limit; i++) {
748 it->push(&_primary_supers[i]);
749 }
750 it->push(&_super);
751 if (!CDSConfig::is_dumping_archive()) {
752 // If dumping archive, these may point to excluded classes. There's no need
753 // to follow these pointers anyway, as they will be set to null in
754 // remove_unshareable_info().
755 it->push((Klass**)&_subklass);
756 it->push((Klass**)&_next_sibling);
757 it->push(&_next_link);
758 }
759
760 vtableEntry* vt = start_of_vtable();
761 for (int i=0; i<vtable_length(); i++) {
762 it->push(vt[i].method_addr());
763 }
764 }
765
766 #if INCLUDE_CDS
767 void Klass::remove_unshareable_info() {
768 assert(CDSConfig::is_dumping_archive(),
769 "only called during CDS dump time");
770 JFR_ONLY(REMOVE_ID(this);)
771 if (log_is_enabled(Trace, cds, unshareable)) {
772 ResourceMark rm;
773 log_trace(cds, unshareable)("remove: %s", external_name());
774 }
775
776 // _secondary_super_cache may be updated by an is_subtype_of() call
777 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
778 // null and let it be repopulated at runtime.
779 set_secondary_super_cache(nullptr);
780
781 set_subklass(nullptr);
782 set_next_sibling(nullptr);
783 set_next_link(nullptr);
784
785 // Null out class_loader_data because we don't share that yet.
786 set_class_loader_data(nullptr);
787 set_is_shared();
788
789 // FIXME: validation in Klass::hash_secondary_supers() may fail for shared klasses.
790 // Even though the bitmaps always match, the canonical order of elements in the table
791 // is not guaranteed to stay the same (see tie breaker during Robin Hood hashing in Klass::hash_insert).
792 //assert(compute_secondary_supers_bitmap(secondary_supers()) == _secondary_supers_bitmap, "broken table");
793 }
794
795 void Klass::remove_java_mirror() {
796 assert(CDSConfig::is_dumping_archive(), "sanity");
797 if (log_is_enabled(Trace, cds, unshareable)) {
798 ResourceMark rm;
799 log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
800 }
801 // Just null out the mirror. The class_loader_data() no longer exists.
802 clear_java_mirror_handle();
803 }
804
805 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
806 assert(is_klass(), "ensure C++ vtable is restored");
807 assert(is_shared(), "must be set");
808 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be");
809 JFR_ONLY(RESTORE_ID(this);)
810 if (log_is_enabled(Trace, cds, unshareable)) {
811 ResourceMark rm(THREAD);
812 oop class_loader = loader_data->class_loader();
813 log_trace(cds, unshareable)("restore: %s with class loader: %s", external_name(),
814 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
815 }
816
817 // If an exception happened during CDS restore, some of these fields may already be
818 // set. We leave the class on the CLD list, even if incomplete so that we don't
819 // modify the CLD list outside a safepoint.
820 if (class_loader_data() == nullptr) {
821 set_class_loader_data(loader_data);
822
823 // Add to class loader list first before creating the mirror
824 // (same order as class file parsing)
825 loader_data->add_class(this);
826 }
827
828 Handle loader(THREAD, loader_data->class_loader());
829 ModuleEntry* module_entry = nullptr;
830 Klass* k = this;
831 if (k->is_objArray_klass()) {
832 k = ObjArrayKlass::cast(k)->bottom_klass();
833 }
834 // Obtain klass' module.
835 if (k->is_instance_klass()) {
836 InstanceKlass* ik = (InstanceKlass*) k;
837 module_entry = ik->module();
838 } else {
839 module_entry = ModuleEntryTable::javabase_moduleEntry();
840 }
841 // Obtain java.lang.Module, if available
842 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module() : (oop)nullptr));
843
844 if (this->has_archived_mirror_index()) {
845 ResourceMark rm(THREAD);
846 log_debug(cds, mirror)("%s has raw archived mirror", external_name());
847 if (ArchiveHeapLoader::is_in_use()) {
848 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
849 protection_domain,
850 CHECK);
851 if (present) {
852 return;
853 }
854 }
855
856 // No archived mirror data
857 log_debug(cds, mirror)("No archived mirror data for %s", external_name());
858 clear_java_mirror_handle();
859 this->clear_archived_mirror_index();
860 }
861
862 // Only recreate it if not present. A previous attempt to restore may have
863 // gotten an OOM later but keep the mirror if it was created.
864 if (java_mirror() == nullptr) {
865 ResourceMark rm(THREAD);
866 log_trace(cds, mirror)("Recreate mirror for %s", external_name());
867 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
868 }
869 }
870 #endif // INCLUDE_CDS
871
872 #if INCLUDE_CDS_JAVA_HEAP
873 oop Klass::archived_java_mirror() {
874 assert(has_archived_mirror_index(), "must have archived mirror");
875 return HeapShared::get_root(_archived_mirror_index);
876 }
877
878 void Klass::clear_archived_mirror_index() {
879 if (_archived_mirror_index >= 0) {
880 HeapShared::clear_root(_archived_mirror_index);
881 }
882 _archived_mirror_index = -1;
883 }
884
885 // No GC barrier
886 void Klass::set_archived_java_mirror(int mirror_index) {
887 assert(CDSConfig::is_dumping_heap(), "sanity");
888 _archived_mirror_index = mirror_index;
889 }
890 #endif // INCLUDE_CDS_JAVA_HEAP
891
892 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
893 if (length > max_length) {
894 if (!THREAD->is_in_internal_oome_mark()) {
895 report_java_out_of_memory("Requested array size exceeds VM limit");
896 JvmtiExport::post_array_size_exhausted();
897 THROW_OOP(Universe::out_of_memory_error_array_size());
898 } else {
899 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
900 }
901 } else if (length < 0) {
902 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
903 }
904 }
905
906 // Replace the last '+' char with '/'.
907 static char* convert_hidden_name_to_java(Symbol* name) {
908 size_t name_len = name->utf8_length();
909 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
910 name->as_klass_external_name(result, (int)name_len + 1);
911 for (int index = (int)name_len; index > 0; index--) {
912 if (result[index] == '+') {
913 result[index] = JVM_SIGNATURE_SLASH;
914 break;
915 }
916 }
917 return result;
918 }
919
920 // In product mode, this function doesn't have virtual function calls so
921 // there might be some performance advantage to handling InstanceKlass here.
922 const char* Klass::external_name() const {
923 if (is_instance_klass()) {
924 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
925 if (ik->is_hidden()) {
926 char* result = convert_hidden_name_to_java(name());
927 return result;
928 }
929 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
930 char* result = convert_hidden_name_to_java(name());
931 return result;
932 }
933 if (name() == nullptr) return "<unknown>";
934 return name()->as_klass_external_name();
935 }
936
937 const char* Klass::signature_name() const {
938 if (name() == nullptr) return "<unknown>";
939 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
940 size_t name_len = name()->utf8_length();
941 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
942 name()->as_C_string(result, (int)name_len + 1);
943 for (int index = (int)name_len; index > 0; index--) {
944 if (result[index] == '+') {
945 result[index] = JVM_SIGNATURE_DOT;
946 break;
947 }
948 }
949 return result;
950 }
951 return name()->as_C_string();
952 }
953
954 const char* Klass::external_kind() const {
955 if (is_interface()) return "interface";
956 if (is_abstract()) return "abstract class";
957 return "class";
958 }
959
960 // Unless overridden, jvmti_class_status has no flags set.
961 jint Klass::jvmti_class_status() const {
962 return 0;
963 }
964
965
966 // Printing
967
968 void Klass::print_on(outputStream* st) const {
969 ResourceMark rm;
970 // print title
971 st->print("%s", internal_name());
972 print_address_on(st);
973 st->cr();
974 }
975
976 #define BULLET " - "
977
978 // Caller needs ResourceMark
979 void Klass::oop_print_on(oop obj, outputStream* st) {
980 // print title
981 st->print_cr("%s ", internal_name());
982 obj->print_address_on(st);
983
984 if (WizardMode) {
985 // print header
986 obj->mark().print_on(st);
987 st->cr();
988 }
989
990 // print class
991 st->print(BULLET"klass: ");
992 obj->klass()->print_value_on(st);
993 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr();
994 st->cr();
995 }
996
997 void Klass::oop_print_value_on(oop obj, outputStream* st) {
998 // print title
999 ResourceMark rm; // Cannot print in debug mode without this
1000 st->print("%s", internal_name());
1001 obj->print_address_on(st);
1002 }
1003
1004 // Verification
1005
1006 void Klass::verify_on(outputStream* st) {
1007
1008 // This can be expensive, but it is worth checking that this klass is actually
1009 // in the CLD graph but not in production.
1010 assert(Metaspace::contains((address)this), "Should be");
1011
1012 guarantee(this->is_klass(),"should be klass");
1013
1014 if (super() != nullptr) {
1015 guarantee(super()->is_klass(), "should be klass");
1016 }
1017 if (secondary_super_cache() != nullptr) {
1018 Klass* ko = secondary_super_cache();
1019 guarantee(ko->is_klass(), "should be klass");
1020 }
1021 for ( uint i = 0; i < primary_super_limit(); i++ ) {
1022 Klass* ko = _primary_supers[i];
1023 if (ko != nullptr) {
1024 guarantee(ko->is_klass(), "should be klass");
1025 }
1026 }
1027
1028 if (java_mirror_no_keepalive() != nullptr) {
1029 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
1030 }
1031 }
1032
1033 void Klass::oop_verify_on(oop obj, outputStream* st) {
1034 guarantee(oopDesc::is_oop(obj), "should be oop");
1035 guarantee(obj->klass()->is_klass(), "klass field is not a klass");
1036 }
1037
1038 bool Klass::is_valid(Klass* k) {
1039 if (!is_aligned(k, sizeof(MetaWord))) return false;
1040 if ((size_t)k < os::min_page_size()) return false;
1041
1042 if (!os::is_readable_range(k, k + 1)) return false;
1043 if (!Metaspace::contains(k)) return false;
1044
1045 if (!Symbol::is_valid(k->name())) return false;
1046 return ClassLoaderDataGraph::is_valid(k->class_loader_data());
1047 }
1048
1049 Method* Klass::method_at_vtable(int index) {
1050 #ifndef PRODUCT
1051 assert(index >= 0, "valid vtable index");
1052 if (DebugVtables) {
1053 verify_vtable_index(index);
1054 }
1055 #endif
1056 return start_of_vtable()[index].method();
1057 }
1058
1059
1060 #ifndef PRODUCT
1061
1062 bool Klass::verify_vtable_index(int i) {
1063 int limit = vtable_length()/vtableEntry::size();
1064 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
1065 return true;
1066 }
1067
1068 #endif // PRODUCT
1069
1070 // Caller needs ResourceMark
1071 // joint_in_module_of_loader provides an optimization if 2 classes are in
1072 // the same module to succinctly print out relevant information about their
1073 // module name and class loader's name_and_id for error messages.
1074 // Format:
1075 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
1076 // are in module <module-name>[@<version>]
1077 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1078 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
1079 assert(module() == class2->module(), "classes do not have the same module");
1080 const char* class1_name = external_name();
1081 size_t len = strlen(class1_name) + 1;
1082
1083 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
1084 len += strlen(class2_description);
1085
1086 len += strlen(" and ");
1087
1088 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1089
1090 // Just return the FQN if error when allocating string
1091 if (joint_description == nullptr) {
1092 return class1_name;
1093 }
1094
1095 jio_snprintf(joint_description, len, "%s and %s",
1096 class1_name,
1097 class2_description);
1098
1099 return joint_description;
1100 }
1101
1102 // Caller needs ResourceMark
1103 // class_in_module_of_loader provides a standard way to include
1104 // relevant information about a class, such as its module name as
1105 // well as its class loader's name_and_id, in error messages and logging.
1106 // Format:
1107 // <fully-qualified-external-class-name> is in module <module-name>[@<version>]
1108 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1109 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
1110 // 1. fully qualified external name of class
1111 const char* klass_name = external_name();
1112 size_t len = strlen(klass_name) + 1;
1113
1114 // 2. module name + @version
1115 const char* module_name = "";
1116 const char* version = "";
1117 bool has_version = false;
1118 bool module_is_named = false;
1119 const char* module_name_phrase = "";
1120 const Klass* bottom_klass = is_objArray_klass() ?
1121 ObjArrayKlass::cast(this)->bottom_klass() : this;
1122 if (bottom_klass->is_instance_klass()) {
1123 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
1124 if (module->is_named()) {
1125 module_is_named = true;
1126 module_name_phrase = "module ";
1127 module_name = module->name()->as_C_string();
1128 len += strlen(module_name);
1129 // Use version if exists and is not a jdk module
1130 if (module->should_show_version()) {
1131 has_version = true;
1132 version = module->version()->as_C_string();
1133 // Include stlen(version) + 1 for the "@"
1134 len += strlen(version) + 1;
1135 }
1136 } else {
1137 module_name = UNNAMED_MODULE;
1138 len += UNNAMED_MODULE_LEN;
1139 }
1140 } else {
1141 // klass is an array of primitives, module is java.base
1142 module_is_named = true;
1143 module_name_phrase = "module ";
1144 module_name = JAVA_BASE_NAME;
1145 len += JAVA_BASE_NAME_LEN;
1146 }
1147
1148 // 3. class loader's name_and_id
1149 ClassLoaderData* cld = class_loader_data();
1150 assert(cld != nullptr, "class_loader_data should not be null");
1151 const char* loader_name_and_id = cld->loader_name_and_id();
1152 len += strlen(loader_name_and_id);
1153
1154 // 4. include parent loader information
1155 const char* parent_loader_phrase = "";
1156 const char* parent_loader_name_and_id = "";
1157 if (include_parent_loader &&
1158 !cld->is_builtin_class_loader_data()) {
1159 oop parent_loader = java_lang_ClassLoader::parent(class_loader());
1160 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
1161 // The parent loader's ClassLoaderData could be null if it is
1162 // a delegating class loader that has never defined a class.
1163 // In this case the loader's name must be obtained via the parent loader's oop.
1164 if (parent_cld == nullptr) {
1165 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
1166 if (cl_name_and_id != nullptr) {
1167 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
1168 }
1169 } else {
1170 parent_loader_name_and_id = parent_cld->loader_name_and_id();
1171 }
1172 parent_loader_phrase = ", parent loader ";
1173 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
1174 }
1175
1176 // Start to construct final full class description string
1177 len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
1178 len += strlen(module_name_phrase) + strlen(" of loader ");
1179
1180 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1181
1182 // Just return the FQN if error when allocating string
1183 if (class_description == nullptr) {
1184 return klass_name;
1185 }
1186
1187 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
1188 klass_name,
1189 (use_are) ? "are" : "is",
1190 module_name_phrase,
1191 module_name,
1192 (has_version) ? "@" : "",
1193 (has_version) ? version : "",
1194 loader_name_and_id,
1195 parent_loader_phrase,
1196 parent_loader_name_and_id);
1197
1198 return class_description;
1199 }
1200
1201 class LookupStats : StackObj {
1202 private:
1203 uint _no_of_samples;
1204 uint _worst;
1205 uint _worst_count;
1206 uint _average;
1207 uint _best;
1208 uint _best_count;
1209 public:
1210 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {}
1211
1212 ~LookupStats() {
1213 assert(_best <= _worst || _no_of_samples == 0, "sanity");
1214 }
1215
1216 void sample(uint value) {
1217 ++_no_of_samples;
1218 _average += value;
1219
1220 if (_worst < value) {
1221 _worst = value;
1222 _worst_count = 1;
1223 } else if (_worst == value) {
1224 ++_worst_count;
1225 }
1226
1227 if (_best > value) {
1228 _best = value;
1229 _best_count = 1;
1230 } else if (_best == value) {
1231 ++_best_count;
1232 }
1233 }
1234
1235 void print_on(outputStream* st) const {
1236 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples);
1237 if (_best_count < _no_of_samples) {
1238 st->print("; average: %4.1f; worst: %2d (%4.1f%%)",
1239 (1.0 * _average) / _no_of_samples,
1240 _worst, (100.0 * _worst_count) / _no_of_samples);
1241 }
1242 }
1243 };
1244
1245 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) {
1246 int num_of_supers = secondary_supers->length();
1247
1248 LookupStats s;
1249 for (int i = 0; i < num_of_supers; i++) {
1250 Klass* secondary_super = secondary_supers->at(i);
1251 int home_slot = Klass::compute_home_slot(secondary_super, bitmap);
1252 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK);
1253 s.sample(score);
1254 }
1255 st->print("positive_lookup: "); s.print_on(st);
1256 }
1257
1258 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) {
1259 assert(~bitmap != 0, "no zeroes");
1260 uintx start = rotate_right(bitmap, slot);
1261 return count_trailing_zeros(~start);
1262 }
1263
1264 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) {
1265 LookupStats s;
1266 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
1267 uint score = compute_distance_to_nearest_zero(slot, bitmap);
1268 s.sample(score);
1269 }
1270 st->print("negative_lookup: "); s.print_on(st);
1271 }
1272
1273 void Klass::print_secondary_supers_on(outputStream* st) const {
1274 if (secondary_supers() != nullptr) {
1275 st->print(" - "); st->print("%d elements;", _secondary_supers->length());
1276 st->print_cr(" bitmap: " UINTX_FORMAT_X_0 ";", _secondary_supers_bitmap);
1277 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY &&
1278 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) {
1279 st->print(" - "); print_positive_lookup_stats(secondary_supers(),
1280 _secondary_supers_bitmap, st); st->cr();
1281 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr();
1282 }
1283 } else {
1284 st->print("null");
1285 }
1286 }
1287
1288 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) {
1289 ResourceMark rm;
1290 super->print();
1291 sub->print();
1292 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d",
1293 msg, sub->external_name(), super->external_name(), linear_result, table_result);
1294 }