1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "cds/archiveHeapLoader.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/classLoaderData.inline.hpp"
30 #include "classfile/classLoaderDataGraph.inline.hpp"
31 #include "classfile/javaClasses.inline.hpp"
32 #include "classfile/moduleEntry.hpp"
33 #include "classfile/systemDictionary.hpp"
34 #include "classfile/systemDictionaryShared.hpp"
35 #include "classfile/vmClasses.hpp"
36 #include "classfile/vmSymbols.hpp"
37 #include "gc/shared/collectedHeap.inline.hpp"
38 #include "jvm_io.h"
39 #include "logging/log.hpp"
40 #include "memory/metadataFactory.hpp"
41 #include "memory/metaspaceClosure.hpp"
42 #include "memory/oopFactory.hpp"
43 #include "memory/resourceArea.hpp"
44 #include "memory/universe.hpp"
45 #include "oops/compressedKlass.inline.hpp"
46 #include "oops/compressedOops.inline.hpp"
47 #include "oops/instanceKlass.hpp"
48 #include "oops/klass.inline.hpp"
49 #include "oops/objArrayKlass.hpp"
50 #include "oops/oop.inline.hpp"
51 #include "oops/oopHandle.inline.hpp"
52 #include "prims/jvmtiExport.hpp"
53 #include "runtime/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 void Klass::initialize_preemptable(TRAPS) {
256 ShouldNotReachHere();
257 }
258
259 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
260 #ifdef ASSERT
261 tty->print_cr("Error: find_field called on a klass oop."
262 " Likely error: reflection method does not correctly"
263 " wrap return value in a mirror object.");
264 #endif
265 ShouldNotReachHere();
266 return nullptr;
267 }
268
269 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
270 OverpassLookupMode overpass_mode,
271 PrivateLookupMode private_mode) const {
272 #ifdef ASSERT
273 tty->print_cr("Error: uncached_lookup_method called on a klass oop."
274 " Likely error: reflection method does not correctly"
275 " wrap return value in a mirror object.");
276 #endif
277 ShouldNotReachHere();
278 return nullptr;
279 }
280
281 static markWord make_prototype(const Klass* kls) {
282 markWord prototype = markWord::prototype();
283 #ifdef _LP64
284 if (UseCompactObjectHeaders) {
285 // With compact object headers, the narrow Klass ID is part of the mark word.
286 // We therfore seed the mark word with the narrow Klass ID.
287 // Note that only those Klass that can be instantiated have a narrow Klass ID.
288 // For those who don't, we leave the klass bits empty and assert if someone
289 // tries to use those.
290 const narrowKlass nk = CompressedKlassPointers::is_encodable(kls) ?
291 CompressedKlassPointers::encode(const_cast<Klass*>(kls)) : 0;
292 prototype = prototype.set_narrow_klass(nk);
293 }
294 #endif
295 return prototype;
296 }
297
298 Klass::Klass() : _kind(UnknownKlassKind) {
299 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
300 }
301
302 // "Normal" instantiation is preceded by a MetaspaceObj allocation
303 // which zeros out memory - calloc equivalent.
304 // The constructor is also used from CppVtableCloner,
305 // which doesn't zero out the memory before calling the constructor.
306 Klass::Klass(KlassKind kind) : _kind(kind),
307 _prototype_header(make_prototype(this)),
308 _shared_class_path_index(-1) {
309 CDS_ONLY(_shared_class_flags = 0;)
310 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
311 _primary_supers[0] = this;
312 set_super_check_offset(in_bytes(primary_supers_offset()));
313 }
314
315 jint Klass::array_layout_helper(BasicType etype) {
316 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
317 // Note that T_ARRAY is not allowed here.
318 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
319 int esize = type2aelembytes(etype);
320 bool isobj = (etype == T_OBJECT);
321 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
322 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
323
324 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
325 assert(layout_helper_is_array(lh), "correct kind");
326 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
327 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
328 assert(layout_helper_header_size(lh) == hsize, "correct decode");
329 assert(layout_helper_element_type(lh) == etype, "correct decode");
330 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
331
332 return lh;
333 }
334
335 int Klass::modifier_flags() const {
336 int mods = java_lang_Class::modifiers(java_mirror());
337 assert(mods == compute_modifier_flags(), "should be same");
338 return mods;
339 }
340
341 bool Klass::can_be_primary_super_slow() const {
342 if (super() == nullptr)
343 return true;
344 else if (super()->super_depth() >= primary_super_limit()-1)
345 return false;
346 else
347 return true;
348 }
349
350 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
351 #ifdef ASSERT
352 if (secondaries != nullptr) {
353 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
354 assert(bitmap == real_bitmap, "must be");
355 assert(secondaries->length() >= (int)population_count(bitmap), "must be");
356 }
357 #endif
358 _secondary_supers_bitmap = bitmap;
359 _secondary_supers = secondaries;
360
361 if (secondaries != nullptr) {
362 LogMessage(class, load) msg;
363 NonInterleavingLogStream log {LogLevel::Debug, msg};
364 if (log.is_enabled()) {
365 ResourceMark rm;
366 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
367 print_secondary_supers_on(&log);
368 }
369 }
370 }
371
372 // Hashed secondary superclasses
373 //
374 // We use a compressed 64-entry hash table with linear probing. We
375 // start by creating a hash table in the usual way, followed by a pass
376 // that removes all the null entries. To indicate which entries would
377 // have been null we use a bitmap that contains a 1 in each position
378 // where an entry is present, 0 otherwise. This bitmap also serves as
379 // a kind of Bloom filter, which in many cases allows us quickly to
380 // eliminate the possibility that something is a member of a set of
381 // secondaries.
382 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
383 const int length = secondaries->length();
384
385 if (length == 0) {
386 return SECONDARY_SUPERS_BITMAP_EMPTY;
387 }
388
389 if (length == 1) {
390 int hash_slot = secondaries->at(0)->hash_slot();
391 return uintx(1) << hash_slot;
392 }
393
394 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)
395
396 // Don't attempt to hash a table that's completely full, because in
397 // the case of an absent interface linear probing would not
398 // terminate.
399 if (length >= SECONDARY_SUPERS_TABLE_SIZE) {
400 return SECONDARY_SUPERS_BITMAP_FULL;
401 }
402
403 {
404 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time());
405
406 ResourceMark rm;
407 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
408 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
409 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
410
411 for (int j = 0; j < length; j++) {
412 Klass* k = secondaries->at(j);
413 hash_insert(k, hashed_secondaries, bitmap);
414 }
415
416 // Pack the hashed secondaries array by copying it into the
417 // secondaries array, sans nulls, if modification is allowed.
418 // Otherwise, validate the order.
419 int i = 0;
420 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
421 bool has_element = ((bitmap >> slot) & 1) != 0;
422 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
423 if (has_element) {
424 Klass* k = hashed_secondaries->at(slot);
425 if (rewrite) {
426 secondaries->at_put(i, k);
427 } else if (secondaries->at(i) != k) {
428 assert(false, "broken secondary supers hash table");
429 return SECONDARY_SUPERS_BITMAP_FULL;
430 }
431 i++;
432 }
433 }
434 assert(i == secondaries->length(), "mismatch");
435 postcond((int)population_count(bitmap) == secondaries->length());
436
437 return bitmap;
438 }
439 }
440
441 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
442 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
443
444 int dist = 0;
445 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
446 Klass* existing = secondaries->at(slot);
447 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
448 if (existing == nullptr) { // no conflict
449 secondaries->at_put(slot, klass);
450 bitmap |= uintx(1) << slot;
451 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
452 return;
453 } else {
454 // Use Robin Hood hashing to minimize the worst case search.
455 // Also, every permutation of the insertion sequence produces
456 // the same final Robin Hood hash table, provided that a
457 // consistent tie breaker is used.
458 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
459 if (existing_dist < dist
460 // This tie breaker ensures that the hash order is maintained.
461 || ((existing_dist == dist)
462 && (uintptr_t(existing) < uintptr_t(klass)))) {
463 Klass* tmp = secondaries->at(slot);
464 secondaries->at_put(slot, klass);
465 klass = tmp;
466 dist = existing_dist;
467 }
468 ++dist;
469 }
470 }
471 }
472
473 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
474 GrowableArray<Klass*>* primaries,
475 GrowableArray<Klass*>* secondaries,
476 uintx& bitmap, TRAPS) {
477 int new_length = primaries->length() + secondaries->length();
478 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
479
480 // Combine the two arrays into a metadata object to pack the array.
481 // The primaries are added in the reverse order, then the secondaries.
482 int fill_p = primaries->length();
483 for (int j = 0; j < fill_p; j++) {
484 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
485 }
486 for( int j = 0; j < secondaries->length(); j++ ) {
487 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
488 }
489 #ifdef ASSERT
490 // We must not copy any null placeholders left over from bootstrap.
491 for (int j = 0; j < secondary_supers->length(); j++) {
492 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
493 }
494 #endif
495
496 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
497 return secondary_supers;
498 }
499
500 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
501 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
502 }
503
504 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
505 uint8_t hash = k->hash_slot();
506 if (hash > 0) {
507 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
508 }
509 return 0;
510 }
511
512
513 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
514 if (k == nullptr) {
515 set_super(nullptr);
516 _primary_supers[0] = this;
517 assert(super_depth() == 0, "Object must already be initialized properly");
518 } else if (k != super() || k == vmClasses::Object_klass()) {
519 assert(super() == nullptr || super() == vmClasses::Object_klass(),
520 "initialize this only once to a non-trivial value");
521 set_super(k);
522 Klass* sup = k;
523 int sup_depth = sup->super_depth();
524 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
525 if (!can_be_primary_super_slow())
526 my_depth = primary_super_limit();
527 for (juint i = 0; i < my_depth; i++) {
528 _primary_supers[i] = sup->_primary_supers[i];
529 }
530 Klass* *super_check_cell;
531 if (my_depth < primary_super_limit()) {
532 _primary_supers[my_depth] = this;
533 super_check_cell = &_primary_supers[my_depth];
534 } else {
535 // Overflow of the primary_supers array forces me to be secondary.
536 super_check_cell = &_secondary_super_cache;
537 }
538 set_super_check_offset(u4((address)super_check_cell - (address) this));
539
540 #ifdef ASSERT
541 {
542 juint j = super_depth();
543 assert(j == my_depth, "computed accessor gets right answer");
544 Klass* t = this;
545 while (!t->can_be_primary_super()) {
546 t = t->super();
547 j = t->super_depth();
548 }
549 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
550 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
551 }
552 while (t != nullptr) {
553 assert(primary_super_of_depth(j) == t, "super list initialization");
554 t = t->super();
555 --j;
556 }
557 assert(j == (juint)-1, "correct depth count");
558 }
559 #endif
560 }
561
562 if (secondary_supers() == nullptr) {
563
564 // Now compute the list of secondary supertypes.
565 // Secondaries can occasionally be on the super chain,
566 // if the inline "_primary_supers" array overflows.
567 int extras = 0;
568 Klass* p;
569 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
570 ++extras;
571 }
572
573 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
574
575 // Compute the "real" non-extra secondaries.
576 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
577 if (secondaries == nullptr) {
578 // secondary_supers set by compute_secondary_supers
579 return;
580 }
581
582 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
583
584 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
585 int i; // Scan for overflow primaries being duplicates of 2nd'arys
586
587 // This happens frequently for very deeply nested arrays: the
588 // primary superclass chain overflows into the secondary. The
589 // secondary list contains the element_klass's secondaries with
590 // an extra array dimension added. If the element_klass's
591 // secondary list already contains some primary overflows, they
592 // (with the extra level of array-ness) will collide with the
593 // normal primary superclass overflows.
594 for( i = 0; i < secondaries->length(); i++ ) {
595 if( secondaries->at(i) == p )
596 break;
597 }
598 if( i < secondaries->length() )
599 continue; // It's a dup, don't put it in
600 primaries->push(p);
601 }
602 // Combine the two arrays into a metadata object to pack the array.
603 uintx bitmap = 0;
604 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
605 set_secondary_supers(s2, bitmap);
606 }
607 }
608
609 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
610 Array<InstanceKlass*>* transitive_interfaces) {
611 assert(num_extra_slots == 0, "override for complex klasses");
612 assert(transitive_interfaces == nullptr, "sanity");
613 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
614 return nullptr;
615 }
616
617
618 // superklass links
619 InstanceKlass* Klass::superklass() const {
620 assert(super() == nullptr || super()->is_instance_klass(), "must be instance klass");
621 return _super == nullptr ? nullptr : InstanceKlass::cast(_super);
622 }
623
624 // subklass links. Used by the compiler (and vtable initialization)
625 // May be cleaned concurrently, so must use the Compile_lock.
626 // The log parameter is for clean_weak_klass_links to report unlinked classes.
627 Klass* Klass::subklass(bool log) const {
628 // Need load_acquire on the _subklass, because it races with inserts that
629 // publishes freshly initialized data.
630 for (Klass* chain = Atomic::load_acquire(&_subklass);
631 chain != nullptr;
632 // Do not need load_acquire on _next_sibling, because inserts never
633 // create _next_sibling edges to dead data.
634 chain = Atomic::load(&chain->_next_sibling))
635 {
636 if (chain->is_loader_alive()) {
637 return chain;
638 } else if (log) {
639 if (log_is_enabled(Trace, class, unload)) {
640 ResourceMark rm;
641 log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
642 }
643 }
644 }
645 return nullptr;
646 }
647
648 Klass* Klass::next_sibling(bool log) const {
649 // Do not need load_acquire on _next_sibling, because inserts never
650 // create _next_sibling edges to dead data.
651 for (Klass* chain = Atomic::load(&_next_sibling);
652 chain != nullptr;
653 chain = Atomic::load(&chain->_next_sibling)) {
654 // Only return alive klass, there may be stale klass
655 // in this chain if cleaned concurrently.
656 if (chain->is_loader_alive()) {
657 return chain;
658 } else if (log) {
659 if (log_is_enabled(Trace, class, unload)) {
660 ResourceMark rm;
661 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
662 }
663 }
664 }
665 return nullptr;
666 }
667
668 void Klass::set_subklass(Klass* s) {
669 assert(s != this, "sanity check");
670 Atomic::release_store(&_subklass, s);
671 }
672
673 void Klass::set_next_sibling(Klass* s) {
674 assert(s != this, "sanity check");
675 // Does not need release semantics. If used by cleanup, it will link to
676 // already safely published data, and if used by inserts, will be published
677 // safely using cmpxchg.
678 Atomic::store(&_next_sibling, s);
679 }
680
681 void Klass::append_to_sibling_list() {
682 if (Universe::is_fully_initialized()) {
683 assert_locked_or_safepoint(Compile_lock);
684 }
685 debug_only(verify();)
686 // add ourselves to superklass' subklass list
687 InstanceKlass* super = superklass();
688 if (super == nullptr) return; // special case: class Object
689 assert((!super->is_interface() // interfaces cannot be supers
690 && (super->superklass() == nullptr || !is_interface())),
691 "an interface can only be a subklass of Object");
692
693 // Make sure there is no stale subklass head
694 super->clean_subklass();
695
696 for (;;) {
697 Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
698 if (prev_first_subklass != nullptr) {
699 // set our sibling to be the superklass' previous first subklass
700 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
701 set_next_sibling(prev_first_subklass);
702 }
703 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
704 // are ever created to not alive klasses. This is an important invariant of the lock-free
705 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
706 if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
707 return;
708 }
709 }
710 debug_only(verify();)
711 }
712
713 void Klass::clean_subklass() {
714 for (;;) {
715 // Need load_acquire, due to contending with concurrent inserts
716 Klass* subklass = Atomic::load_acquire(&_subklass);
717 if (subklass == nullptr || subklass->is_loader_alive()) {
718 return;
719 }
720 // Try to fix _subklass until it points at something not dead.
721 Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
722 }
723 }
724
725 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
726 if (!ClassUnloading || !unloading_occurred) {
727 return;
728 }
729
730 Klass* root = vmClasses::Object_klass();
731 Stack<Klass*, mtGC> stack;
732
733 stack.push(root);
734 while (!stack.is_empty()) {
735 Klass* current = stack.pop();
736
737 assert(current->is_loader_alive(), "just checking, this should be live");
738
739 // Find and set the first alive subklass
740 Klass* sub = current->subklass(true);
741 current->clean_subklass();
742 if (sub != nullptr) {
743 stack.push(sub);
744 }
745
746 // Find and set the first alive sibling
747 Klass* sibling = current->next_sibling(true);
748 current->set_next_sibling(sibling);
749 if (sibling != nullptr) {
750 stack.push(sibling);
751 }
752
753 // Clean the implementors list and method data.
754 if (clean_alive_klasses && current->is_instance_klass()) {
755 InstanceKlass* ik = InstanceKlass::cast(current);
756 ik->clean_weak_instanceklass_links();
757
758 // JVMTI RedefineClasses creates previous versions that are not in
759 // the class hierarchy, so process them here.
760 while ((ik = ik->previous_versions()) != nullptr) {
761 ik->clean_weak_instanceklass_links();
762 }
763 }
764 }
765 }
766
767 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
768 if (log_is_enabled(Trace, cds)) {
769 ResourceMark rm;
770 log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
771 }
772
773 it->push(&_name);
774 it->push(&_secondary_supers);
775 for (int i = 0; i < _primary_super_limit; i++) {
776 it->push(&_primary_supers[i]);
777 }
778 it->push(&_super);
779 if (!CDSConfig::is_dumping_archive()) {
780 // If dumping archive, these may point to excluded classes. There's no need
781 // to follow these pointers anyway, as they will be set to null in
782 // remove_unshareable_info().
783 it->push((Klass**)&_subklass);
784 it->push((Klass**)&_next_sibling);
785 it->push(&_next_link);
786 }
787
788 vtableEntry* vt = start_of_vtable();
789 for (int i=0; i<vtable_length(); i++) {
790 it->push(vt[i].method_addr());
791 }
792 }
793
794 #if INCLUDE_CDS
795 void Klass::remove_unshareable_info() {
796 assert(CDSConfig::is_dumping_archive(),
797 "only called during CDS dump time");
798 JFR_ONLY(REMOVE_ID(this);)
799 if (log_is_enabled(Trace, cds, unshareable)) {
800 ResourceMark rm;
801 log_trace(cds, unshareable)("remove: %s", external_name());
802 }
803
804 // _secondary_super_cache may be updated by an is_subtype_of() call
805 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
806 // null and let it be repopulated at runtime.
807 set_secondary_super_cache(nullptr);
808
809 set_subklass(nullptr);
810 set_next_sibling(nullptr);
811 set_next_link(nullptr);
812
813 // Null out class_loader_data because we don't share that yet.
814 set_class_loader_data(nullptr);
815 set_is_shared();
816
817 // FIXME: validation in Klass::hash_secondary_supers() may fail for shared klasses.
818 // Even though the bitmaps always match, the canonical order of elements in the table
819 // is not guaranteed to stay the same (see tie breaker during Robin Hood hashing in Klass::hash_insert).
820 //assert(compute_secondary_supers_bitmap(secondary_supers()) == _secondary_supers_bitmap, "broken table");
821 }
822
823 void Klass::remove_java_mirror() {
824 assert(CDSConfig::is_dumping_archive(), "sanity");
825 if (log_is_enabled(Trace, cds, unshareable)) {
826 ResourceMark rm;
827 log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
828 }
829
830 #if INCLUDE_CDS_JAVA_HEAP
831 _archived_mirror_index = -1;
832 if (CDSConfig::is_dumping_heap()) {
833 Klass* src_k = ArchiveBuilder::current()->get_source_addr(this);
834 oop orig_mirror = src_k->java_mirror();
835 if (orig_mirror == nullptr) {
836 assert(CDSConfig::is_dumping_final_static_archive(), "sanity");
837 if (is_instance_klass()) {
838 assert(InstanceKlass::cast(this)->is_shared_unregistered_class(), "sanity");
839 } else {
840 precond(is_objArray_klass());
841 Klass *k = ObjArrayKlass::cast(this)->bottom_klass();
842 precond(k->is_instance_klass());
843 assert(InstanceKlass::cast(k)->is_shared_unregistered_class(), "sanity");
844 }
845 } else {
846 oop scratch_mirror = HeapShared::scratch_java_mirror(orig_mirror);
847 if (scratch_mirror != nullptr) {
848 _archived_mirror_index = HeapShared::append_root(scratch_mirror);
849 }
850 }
851 }
852 #endif
853
854 // Just null out the mirror. The class_loader_data() no longer exists.
855 clear_java_mirror_handle();
856 }
857
858 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
859 assert(is_klass(), "ensure C++ vtable is restored");
860 assert(is_shared(), "must be set");
861 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be");
862 JFR_ONLY(RESTORE_ID(this);)
863 if (log_is_enabled(Trace, cds, unshareable)) {
864 ResourceMark rm(THREAD);
865 oop class_loader = loader_data->class_loader();
866 log_trace(cds, unshareable)("restore: %s with class loader: %s", external_name(),
867 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
868 }
869
870 // If an exception happened during CDS restore, some of these fields may already be
871 // set. We leave the class on the CLD list, even if incomplete so that we don't
872 // modify the CLD list outside a safepoint.
873 if (class_loader_data() == nullptr) {
874 set_class_loader_data(loader_data);
875
876 // Add to class loader list first before creating the mirror
877 // (same order as class file parsing)
878 loader_data->add_class(this);
879 }
880
881 Handle loader(THREAD, loader_data->class_loader());
882 ModuleEntry* module_entry = nullptr;
883 Klass* k = this;
884 if (k->is_objArray_klass()) {
885 k = ObjArrayKlass::cast(k)->bottom_klass();
886 }
887 // Obtain klass' module.
888 if (k->is_instance_klass()) {
889 InstanceKlass* ik = (InstanceKlass*) k;
890 module_entry = ik->module();
891 } else {
892 module_entry = ModuleEntryTable::javabase_moduleEntry();
893 }
894 // Obtain java.lang.Module, if available
895 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module() : (oop)nullptr));
896
897 if (this->has_archived_mirror_index()) {
898 ResourceMark rm(THREAD);
899 log_debug(cds, mirror)("%s has raw archived mirror", external_name());
900 if (ArchiveHeapLoader::is_in_use()) {
901 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
902 protection_domain,
903 CHECK);
904 if (present) {
905 return;
906 }
907 }
908
909 // No archived mirror data
910 log_debug(cds, mirror)("No archived mirror data for %s", external_name());
911 clear_java_mirror_handle();
912 this->clear_archived_mirror_index();
913 }
914
915 // Only recreate it if not present. A previous attempt to restore may have
916 // gotten an OOM later but keep the mirror if it was created.
917 if (java_mirror() == nullptr) {
918 ResourceMark rm(THREAD);
919 log_trace(cds, mirror)("Recreate mirror for %s", external_name());
920 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
921 }
922 }
923 #endif // INCLUDE_CDS
924
925 #if INCLUDE_CDS_JAVA_HEAP
926 oop Klass::archived_java_mirror() {
927 assert(has_archived_mirror_index(), "must have archived mirror");
928 return HeapShared::get_root(_archived_mirror_index);
929 }
930
931 void Klass::clear_archived_mirror_index() {
932 if (_archived_mirror_index >= 0) {
933 HeapShared::clear_root(_archived_mirror_index);
934 }
935 _archived_mirror_index = -1;
936 }
937 #endif // INCLUDE_CDS_JAVA_HEAP
938
939 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
940 if (length > max_length) {
941 if (!THREAD->is_in_internal_oome_mark()) {
942 report_java_out_of_memory("Requested array size exceeds VM limit");
943 JvmtiExport::post_array_size_exhausted();
944 THROW_OOP(Universe::out_of_memory_error_array_size());
945 } else {
946 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
947 }
948 } else if (length < 0) {
949 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
950 }
951 }
952
953 // Replace the last '+' char with '/'.
954 static char* convert_hidden_name_to_java(Symbol* name) {
955 size_t name_len = name->utf8_length();
956 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
957 name->as_klass_external_name(result, (int)name_len + 1);
958 for (int index = (int)name_len; index > 0; index--) {
959 if (result[index] == '+') {
960 result[index] = JVM_SIGNATURE_SLASH;
961 break;
962 }
963 }
964 return result;
965 }
966
967 // In product mode, this function doesn't have virtual function calls so
968 // there might be some performance advantage to handling InstanceKlass here.
969 const char* Klass::external_name() const {
970 if (is_instance_klass()) {
971 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
972 if (ik->is_hidden()) {
973 char* result = convert_hidden_name_to_java(name());
974 return result;
975 }
976 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
977 char* result = convert_hidden_name_to_java(name());
978 return result;
979 }
980 if (name() == nullptr) return "<unknown>";
981 return name()->as_klass_external_name();
982 }
983
984 const char* Klass::signature_name() const {
985 if (name() == nullptr) return "<unknown>";
986 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
987 size_t name_len = name()->utf8_length();
988 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
989 name()->as_C_string(result, (int)name_len + 1);
990 for (int index = (int)name_len; index > 0; index--) {
991 if (result[index] == '+') {
992 result[index] = JVM_SIGNATURE_DOT;
993 break;
994 }
995 }
996 return result;
997 }
998 return name()->as_C_string();
999 }
1000
1001 const char* Klass::external_kind() const {
1002 if (is_interface()) return "interface";
1003 if (is_abstract()) return "abstract class";
1004 return "class";
1005 }
1006
1007 // Unless overridden, jvmti_class_status has no flags set.
1008 jint Klass::jvmti_class_status() const {
1009 return 0;
1010 }
1011
1012
1013 // Printing
1014
1015 void Klass::print_on(outputStream* st) const {
1016 ResourceMark rm;
1017 // print title
1018 st->print("%s", internal_name());
1019 print_address_on(st);
1020 st->cr();
1021 }
1022
1023 #define BULLET " - "
1024
1025 // Caller needs ResourceMark
1026 void Klass::oop_print_on(oop obj, outputStream* st) {
1027 // print title
1028 st->print_cr("%s ", internal_name());
1029 obj->print_address_on(st);
1030
1031 if (WizardMode) {
1032 // print header
1033 obj->mark().print_on(st);
1034 st->cr();
1035 if (UseCompactObjectHeaders) {
1036 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
1037 st->cr();
1038 }
1039 }
1040
1041 // print class
1042 st->print(BULLET"klass: ");
1043 obj->klass()->print_value_on(st);
1044 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr();
1045 st->cr();
1046 }
1047
1048 void Klass::oop_print_value_on(oop obj, outputStream* st) {
1049 // print title
1050 ResourceMark rm; // Cannot print in debug mode without this
1051 st->print("%s", internal_name());
1052 obj->print_address_on(st);
1053 }
1054
1055 // Verification
1056
1057 void Klass::verify_on(outputStream* st) {
1058
1059 // This can be expensive, but it is worth checking that this klass is actually
1060 // in the CLD graph but not in production.
1061 #ifdef ASSERT
1062 if (UseCompressedClassPointers && needs_narrow_id()) {
1063 // Stricter checks for both correct alignment and placement
1064 CompressedKlassPointers::check_encodable(this);
1065 } else {
1066 assert(Metaspace::contains((address)this), "Should be");
1067 }
1068 #endif // ASSERT
1069
1070 guarantee(this->is_klass(),"should be klass");
1071
1072 if (super() != nullptr) {
1073 guarantee(super()->is_klass(), "should be klass");
1074 }
1075 if (secondary_super_cache() != nullptr) {
1076 Klass* ko = secondary_super_cache();
1077 guarantee(ko->is_klass(), "should be klass");
1078 }
1079 for ( uint i = 0; i < primary_super_limit(); i++ ) {
1080 Klass* ko = _primary_supers[i];
1081 if (ko != nullptr) {
1082 guarantee(ko->is_klass(), "should be klass");
1083 }
1084 }
1085
1086 if (java_mirror_no_keepalive() != nullptr) {
1087 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
1088 }
1089 }
1090
1091 void Klass::oop_verify_on(oop obj, outputStream* st) {
1092 guarantee(oopDesc::is_oop(obj), "should be oop");
1093 guarantee(obj->klass()->is_klass(), "klass field is not a klass");
1094 }
1095
1096 // Note: this function is called with an address that may or may not be a Klass.
1097 // The point is not to assert it is but to check if it could be.
1098 bool Klass::is_valid(Klass* k) {
1099 if (!is_aligned(k, sizeof(MetaWord))) return false;
1100 if ((size_t)k < os::min_page_size()) return false;
1101
1102 if (!os::is_readable_range(k, k + 1)) return false;
1103 if (!Metaspace::contains(k)) return false;
1104
1105 if (!Symbol::is_valid(k->name())) return false;
1106 return ClassLoaderDataGraph::is_valid(k->class_loader_data());
1107 }
1108
1109 Method* Klass::method_at_vtable(int index) {
1110 #ifndef PRODUCT
1111 assert(index >= 0, "valid vtable index");
1112 if (DebugVtables) {
1113 verify_vtable_index(index);
1114 }
1115 #endif
1116 return start_of_vtable()[index].method();
1117 }
1118
1119
1120 #ifndef PRODUCT
1121
1122 bool Klass::verify_vtable_index(int i) {
1123 int limit = vtable_length()/vtableEntry::size();
1124 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
1125 return true;
1126 }
1127
1128 #endif // PRODUCT
1129
1130 // Caller needs ResourceMark
1131 // joint_in_module_of_loader provides an optimization if 2 classes are in
1132 // the same module to succinctly print out relevant information about their
1133 // module name and class loader's name_and_id for error messages.
1134 // Format:
1135 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
1136 // are in module <module-name>[@<version>]
1137 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1138 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
1139 assert(module() == class2->module(), "classes do not have the same module");
1140 const char* class1_name = external_name();
1141 size_t len = strlen(class1_name) + 1;
1142
1143 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
1144 len += strlen(class2_description);
1145
1146 len += strlen(" and ");
1147
1148 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1149
1150 // Just return the FQN if error when allocating string
1151 if (joint_description == nullptr) {
1152 return class1_name;
1153 }
1154
1155 jio_snprintf(joint_description, len, "%s and %s",
1156 class1_name,
1157 class2_description);
1158
1159 return joint_description;
1160 }
1161
1162 // Caller needs ResourceMark
1163 // class_in_module_of_loader provides a standard way to include
1164 // relevant information about a class, such as its module name as
1165 // well as its class loader's name_and_id, in error messages and logging.
1166 // Format:
1167 // <fully-qualified-external-class-name> is in module <module-name>[@<version>]
1168 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1169 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
1170 // 1. fully qualified external name of class
1171 const char* klass_name = external_name();
1172 size_t len = strlen(klass_name) + 1;
1173
1174 // 2. module name + @version
1175 const char* module_name = "";
1176 const char* version = "";
1177 bool has_version = false;
1178 bool module_is_named = false;
1179 const char* module_name_phrase = "";
1180 const Klass* bottom_klass = is_objArray_klass() ?
1181 ObjArrayKlass::cast(this)->bottom_klass() : this;
1182 if (bottom_klass->is_instance_klass()) {
1183 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
1184 if (module->is_named()) {
1185 module_is_named = true;
1186 module_name_phrase = "module ";
1187 module_name = module->name()->as_C_string();
1188 len += strlen(module_name);
1189 // Use version if exists and is not a jdk module
1190 if (module->should_show_version()) {
1191 has_version = true;
1192 version = module->version()->as_C_string();
1193 // Include stlen(version) + 1 for the "@"
1194 len += strlen(version) + 1;
1195 }
1196 } else {
1197 module_name = UNNAMED_MODULE;
1198 len += UNNAMED_MODULE_LEN;
1199 }
1200 } else {
1201 // klass is an array of primitives, module is java.base
1202 module_is_named = true;
1203 module_name_phrase = "module ";
1204 module_name = JAVA_BASE_NAME;
1205 len += JAVA_BASE_NAME_LEN;
1206 }
1207
1208 // 3. class loader's name_and_id
1209 ClassLoaderData* cld = class_loader_data();
1210 assert(cld != nullptr, "class_loader_data should not be null");
1211 const char* loader_name_and_id = cld->loader_name_and_id();
1212 len += strlen(loader_name_and_id);
1213
1214 // 4. include parent loader information
1215 const char* parent_loader_phrase = "";
1216 const char* parent_loader_name_and_id = "";
1217 if (include_parent_loader &&
1218 !cld->is_builtin_class_loader_data()) {
1219 oop parent_loader = java_lang_ClassLoader::parent(class_loader());
1220 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
1221 // The parent loader's ClassLoaderData could be null if it is
1222 // a delegating class loader that has never defined a class.
1223 // In this case the loader's name must be obtained via the parent loader's oop.
1224 if (parent_cld == nullptr) {
1225 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
1226 if (cl_name_and_id != nullptr) {
1227 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
1228 }
1229 } else {
1230 parent_loader_name_and_id = parent_cld->loader_name_and_id();
1231 }
1232 parent_loader_phrase = ", parent loader ";
1233 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
1234 }
1235
1236 // Start to construct final full class description string
1237 len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
1238 len += strlen(module_name_phrase) + strlen(" of loader ");
1239
1240 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1241
1242 // Just return the FQN if error when allocating string
1243 if (class_description == nullptr) {
1244 return klass_name;
1245 }
1246
1247 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
1248 klass_name,
1249 (use_are) ? "are" : "is",
1250 module_name_phrase,
1251 module_name,
1252 (has_version) ? "@" : "",
1253 (has_version) ? version : "",
1254 loader_name_and_id,
1255 parent_loader_phrase,
1256 parent_loader_name_and_id);
1257
1258 return class_description;
1259 }
1260
1261 class LookupStats : StackObj {
1262 private:
1263 uint _no_of_samples;
1264 uint _worst;
1265 uint _worst_count;
1266 uint _average;
1267 uint _best;
1268 uint _best_count;
1269 public:
1270 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {}
1271
1272 ~LookupStats() {
1273 assert(_best <= _worst || _no_of_samples == 0, "sanity");
1274 }
1275
1276 void sample(uint value) {
1277 ++_no_of_samples;
1278 _average += value;
1279
1280 if (_worst < value) {
1281 _worst = value;
1282 _worst_count = 1;
1283 } else if (_worst == value) {
1284 ++_worst_count;
1285 }
1286
1287 if (_best > value) {
1288 _best = value;
1289 _best_count = 1;
1290 } else if (_best == value) {
1291 ++_best_count;
1292 }
1293 }
1294
1295 void print_on(outputStream* st) const {
1296 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples);
1297 if (_best_count < _no_of_samples) {
1298 st->print("; average: %4.1f; worst: %2d (%4.1f%%)",
1299 (1.0 * _average) / _no_of_samples,
1300 _worst, (100.0 * _worst_count) / _no_of_samples);
1301 }
1302 }
1303 };
1304
1305 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) {
1306 int num_of_supers = secondary_supers->length();
1307
1308 LookupStats s;
1309 for (int i = 0; i < num_of_supers; i++) {
1310 Klass* secondary_super = secondary_supers->at(i);
1311 int home_slot = Klass::compute_home_slot(secondary_super, bitmap);
1312 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK);
1313 s.sample(score);
1314 }
1315 st->print("positive_lookup: "); s.print_on(st);
1316 }
1317
1318 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) {
1319 assert(~bitmap != 0, "no zeroes");
1320 uintx start = rotate_right(bitmap, slot);
1321 return count_trailing_zeros(~start);
1322 }
1323
1324 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) {
1325 LookupStats s;
1326 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
1327 uint score = compute_distance_to_nearest_zero(slot, bitmap);
1328 s.sample(score);
1329 }
1330 st->print("negative_lookup: "); s.print_on(st);
1331 }
1332
1333 void Klass::print_secondary_supers_on(outputStream* st) const {
1334 if (secondary_supers() != nullptr) {
1335 st->print(" - "); st->print("%d elements;", _secondary_supers->length());
1336 st->print_cr(" bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap);
1337 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY &&
1338 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) {
1339 st->print(" - "); print_positive_lookup_stats(secondary_supers(),
1340 _secondary_supers_bitmap, st); st->cr();
1341 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr();
1342 }
1343 } else {
1344 st->print("null");
1345 }
1346 }
1347
1348 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) {
1349 ResourceMark rm;
1350 super->print();
1351 sub->print();
1352 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d",
1353 msg, sub->external_name(), super->external_name(), linear_result, table_result);
1354 }