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