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/cdsConfig.hpp"
26 #include "cds/heapShared.inline.hpp"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/classLoaderData.inline.hpp"
29 #include "classfile/classLoaderDataGraph.inline.hpp"
30 #include "classfile/javaClasses.inline.hpp"
31 #include "classfile/moduleEntry.hpp"
32 #include "classfile/systemDictionary.hpp"
33 #include "classfile/systemDictionaryShared.hpp"
34 #include "classfile/vmClasses.hpp"
35 #include "classfile/vmSymbols.hpp"
36 #include "gc/shared/collectedHeap.inline.hpp"
37 #include "jvm_io.h"
38 #include "logging/log.hpp"
39 #include "memory/metadataFactory.hpp"
40 #include "memory/metaspaceClosure.hpp"
41 #include "memory/oopFactory.hpp"
42 #include "memory/resourceArea.hpp"
43 #include "memory/universe.hpp"
44 #include "oops/compressedKlass.inline.hpp"
45 #include "oops/compressedOops.inline.hpp"
46 #include "oops/instanceKlass.hpp"
47 #include "oops/klass.inline.hpp"
48 #include "oops/objArrayKlass.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "oops/oopHandle.inline.hpp"
51 #include "prims/jvmtiExport.hpp"
52 #include "runtime/atomicAccess.hpp"
53 #include "runtime/handles.inline.hpp"
54 #include "runtime/perfData.hpp"
55 #include "utilities/macros.hpp"
56 #include "utilities/powerOfTwo.hpp"
57 #include "utilities/rotate_bits.hpp"
58 #include "utilities/stack.inline.hpp"
59
60 #if INCLUDE_JFR
61 #include "jfr/jfr.hpp"
62 #endif
63
64 void Klass::set_java_mirror(Handle m) {
65 assert(!m.is_null(), "New mirror should never be null.");
66 assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
67 _java_mirror = class_loader_data()->add_handle(m);
68 }
69
70 bool Klass::is_cloneable() const {
71 return _misc_flags.is_cloneable_fast() ||
72 is_subtype_of(vmClasses::Cloneable_klass());
73 }
74
75 uint8_t Klass::compute_hash_slot(Symbol* n) {
76 uint hash_code;
77 // Special cases for the two superclasses of all Array instances.
78 // Code elsewhere assumes, for all instances of ArrayKlass, that
79 // these two interfaces will be in this order.
80
81 // We ensure there are some empty slots in the hash table between
82 // these two very common interfaces because if they were adjacent
83 // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1
84 // would result in a probe length of 3.
85 if (n == vmSymbols::java_lang_Cloneable()) {
86 hash_code = 0;
87 } else if (n == vmSymbols::java_io_Serializable()) {
88 hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2;
89 } else {
90 auto s = (const jbyte*) n->bytes();
91 hash_code = java_lang_String::hash_code(s, n->utf8_length());
92 // We use String::hash_code here (rather than e.g.
93 // Symbol::identity_hash()) in order to have a hash code that
94 // does not change from run to run. We want that because the
95 // hash value for a secondary superclass appears in generated
96 // code as a constant.
97
98 // This constant is magic: see Knuth, "Fibonacci Hashing".
99 constexpr uint multiplier
100 = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 ))
101 constexpr uint hash_shift = sizeof(hash_code) * 8 - 6;
102 // The leading bits of the least significant half of the product.
103 hash_code = (hash_code * multiplier) >> hash_shift;
104
105 if (StressSecondarySupers) {
106 // Generate many hash collisions in order to stress-test the
107 // linear search fallback.
108 hash_code = hash_code % 3;
109 hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3);
110 }
111 }
112
113 return (hash_code & SECONDARY_SUPERS_TABLE_MASK);
114 }
115
116 void Klass::set_name(Symbol* n) {
117 _name = n;
118
119 if (_name != nullptr) {
120 _name->increment_refcount();
121 }
122
123 {
124 elapsedTimer selftime;
125 selftime.start();
126
127 _hash_slot = compute_hash_slot(n);
128 assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required");
129
130 selftime.stop();
131 if (UsePerfData) {
132 ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks());
133 }
134 }
135
136 if (CDSConfig::is_dumping_archive() && is_instance_klass()) {
137 SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
138 }
139 }
140
141 bool Klass::is_subclass_of(const Klass* k) const {
142 // Run up the super chain and check
143 if (this == k) return true;
144
145 Klass* t = const_cast<Klass*>(this)->super();
146
147 while (t != nullptr) {
148 if (t == k) return true;
149 t = t->super();
150 }
151 return false;
152 }
153
154 void Klass::release_C_heap_structures(bool release_constant_pool) {
155 if (_name != nullptr) _name->decrement_refcount();
156 }
157
158 bool Klass::linear_search_secondary_supers(const Klass* k) const {
159 // Scan the array-of-objects for a match
160 // FIXME: We could do something smarter here, maybe a vectorized
161 // comparison or a binary search, but is that worth any added
162 // complexity?
163 int cnt = secondary_supers()->length();
164 for (int i = 0; i < cnt; i++) {
165 if (secondary_supers()->at(i) == k) {
166 return true;
167 }
168 }
169 return false;
170 }
171
172 // Given a secondary superklass k, an initial array index, and an
173 // occupancy bitmap rotated such that Bit 1 is the next bit to test,
174 // search for k.
175 bool Klass::fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const {
176 // Once the occupancy bitmap is almost full, it's faster to use a
177 // linear search.
178 if (secondary_supers()->length() > SECONDARY_SUPERS_TABLE_SIZE - 2) {
179 return linear_search_secondary_supers(k);
180 }
181
182 // This is conventional linear probing, but instead of terminating
183 // when a null entry is found in the table, we maintain a bitmap
184 // in which a 0 indicates missing entries.
185
186 precond((int)population_count(rotated_bitmap) == secondary_supers()->length());
187
188 // The check for secondary_supers()->length() <= SECONDARY_SUPERS_TABLE_SIZE - 2
189 // at the start of this function guarantees there are 0s in the
190 // bitmap, so this loop eventually terminates.
191 while ((rotated_bitmap & 2) != 0) {
192 if (++index == secondary_supers()->length()) {
193 index = 0;
194 }
195 if (secondary_supers()->at(index) == k) {
196 return true;
197 }
198 rotated_bitmap = rotate_right(rotated_bitmap, 1);
199 }
200 return false;
201 }
202
203 // Return self, except for abstract classes with exactly 1
204 // implementor. Then return the 1 concrete implementation.
205 Klass *Klass::up_cast_abstract() {
206 Klass *r = this;
207 while( r->is_abstract() ) { // Receiver is abstract?
208 Klass *s = r->subklass(); // Check for exactly 1 subklass
209 if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up
210 return this; // Return 'this' as a no-progress flag
211 r = s; // Loop till find concrete class
212 }
213 return r; // Return the 1 concrete class
214 }
215
216 // Find LCA in class hierarchy
217 Klass *Klass::LCA( Klass *k2 ) {
218 Klass *k1 = this;
219 while( 1 ) {
220 if( k1->is_subtype_of(k2) ) return k2;
221 if( k2->is_subtype_of(k1) ) return k1;
222 k1 = k1->super();
223 k2 = k2->super();
224 }
225 }
226
227
228 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
229 ResourceMark rm(THREAD);
230 THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
231 : vmSymbols::java_lang_InstantiationException(), external_name());
232 }
233
234
235 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
236 ResourceMark rm(THREAD);
237 assert(s != nullptr, "Throw NPE!");
238 THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
239 err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
240 }
241
242
243 void Klass::initialize(TRAPS) {
244 ShouldNotReachHere();
245 }
246
247 void Klass::initialize_preemptable(TRAPS) {
248 ShouldNotReachHere();
249 }
250
251 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
252 #ifdef ASSERT
253 tty->print_cr("Error: find_field called on a klass oop."
254 " Likely error: reflection method does not correctly"
255 " wrap return value in a mirror object.");
256 #endif
257 ShouldNotReachHere();
258 return nullptr;
259 }
260
261 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
262 OverpassLookupMode overpass_mode,
263 PrivateLookupMode private_mode) const {
264 #ifdef ASSERT
265 tty->print_cr("Error: uncached_lookup_method called on a klass oop."
266 " Likely error: reflection method does not correctly"
267 " wrap return value in a mirror object.");
268 #endif
269 ShouldNotReachHere();
270 return nullptr;
271 }
272
273 static markWord make_prototype(const Klass* kls) {
274 markWord prototype = markWord::prototype();
275 #ifdef _LP64
276 if (UseCompactObjectHeaders) {
277 // With compact object headers, the narrow Klass ID is part of the mark word.
278 // We therefore seed the mark word with the narrow Klass ID.
279 precond(CompressedKlassPointers::is_encodable(kls));
280 const narrowKlass nk = CompressedKlassPointers::encode(const_cast<Klass*>(kls));
281 prototype = prototype.set_narrow_klass(nk);
282 }
283 #endif
284 return prototype;
285 }
286
287 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() {
288 return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD);
289 }
290
291 Klass::Klass() : _kind(UnknownKlassKind) {
292 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
293 }
294
295 // "Normal" instantiation is preceded by a MetaspaceObj allocation
296 // which zeros out memory - calloc equivalent.
297 // The constructor is also used from CppVtableCloner,
298 // which doesn't zero out the memory before calling the constructor.
299 Klass::Klass(KlassKind kind) : _kind(kind),
300 _prototype_header(make_prototype(this)),
301 _shared_class_path_index(-1) {
302 CDS_ONLY(_aot_class_flags = 0;)
303 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
304 _primary_supers[0] = this;
305 set_super_check_offset(in_bytes(primary_supers_offset()));
306 }
307
308 jint Klass::array_layout_helper(BasicType etype) {
309 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
310 // Note that T_ARRAY is not allowed here.
311 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
312 int esize = type2aelembytes(etype);
313 bool isobj = (etype == T_OBJECT);
314 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
315 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
316
317 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
318 assert(layout_helper_is_array(lh), "correct kind");
319 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
320 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
321 assert(layout_helper_header_size(lh) == hsize, "correct decode");
322 assert(layout_helper_element_type(lh) == etype, "correct decode");
323 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
324
325 return lh;
326 }
327
328 int Klass::modifier_flags() const {
329 int mods = java_lang_Class::modifiers(java_mirror());
330 assert(mods == compute_modifier_flags(), "should be same");
331 return mods;
332 }
333
334 bool Klass::can_be_primary_super_slow() const {
335 if (super() == nullptr)
336 return true;
337 else if (super()->super_depth() >= primary_super_limit()-1)
338 return false;
339 else
340 return true;
341 }
342
343 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
344 #ifdef ASSERT
345 if (secondaries != nullptr) {
346 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
347 assert(bitmap == real_bitmap, "must be");
348 assert(secondaries->length() >= (int)population_count(bitmap), "must be");
349 }
350 #endif
351 _secondary_supers_bitmap = bitmap;
352 _secondary_supers = secondaries;
353
354 if (secondaries != nullptr) {
355 LogMessage(class, load) msg;
356 NonInterleavingLogStream log {LogLevel::Debug, msg};
357 if (log.is_enabled()) {
358 ResourceMark rm;
359 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
360 print_secondary_supers_on(&log);
361 }
362 }
363 }
364
365 // Hashed secondary superclasses
366 //
367 // We use a compressed 64-entry hash table with linear probing. We
368 // start by creating a hash table in the usual way, followed by a pass
369 // that removes all the null entries. To indicate which entries would
370 // have been null we use a bitmap that contains a 1 in each position
371 // where an entry is present, 0 otherwise. This bitmap also serves as
372 // a kind of Bloom filter, which in many cases allows us quickly to
373 // eliminate the possibility that something is a member of a set of
374 // secondaries.
375 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
376 const int length = secondaries->length();
377
378 if (length == 0) {
379 return SECONDARY_SUPERS_BITMAP_EMPTY;
380 }
381
382 if (length == 1) {
383 int hash_slot = secondaries->at(0)->hash_slot();
384 return uintx(1) << hash_slot;
385 }
386
387 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)
388
389 // Don't attempt to hash a table that's completely full, because in
390 // the case of an absent interface linear probing would not
391 // terminate.
392 if (length >= SECONDARY_SUPERS_TABLE_SIZE) {
393 return SECONDARY_SUPERS_BITMAP_FULL;
394 }
395
396 {
397 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time());
398
399 ResourceMark rm;
400 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
401 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
402 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
403
404 for (int j = 0; j < length; j++) {
405 Klass* k = secondaries->at(j);
406 hash_insert(k, hashed_secondaries, bitmap);
407 }
408
409 // Pack the hashed secondaries array by copying it into the
410 // secondaries array, sans nulls, if modification is allowed.
411 // Otherwise, validate the order.
412 int i = 0;
413 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
414 bool has_element = ((bitmap >> slot) & 1) != 0;
415 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
416 if (has_element) {
417 Klass* k = hashed_secondaries->at(slot);
418 if (rewrite) {
419 secondaries->at_put(i, k);
420 } else if (secondaries->at(i) != k) {
421 assert(false, "broken secondary supers hash table");
422 return SECONDARY_SUPERS_BITMAP_FULL;
423 }
424 i++;
425 }
426 }
427 assert(i == secondaries->length(), "mismatch");
428 postcond((int)population_count(bitmap) == secondaries->length());
429
430 return bitmap;
431 }
432 }
433
434 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
435 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
436
437 int dist = 0;
438 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
439 Klass* existing = secondaries->at(slot);
440 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
441 if (existing == nullptr) { // no conflict
442 secondaries->at_put(slot, klass);
443 bitmap |= uintx(1) << slot;
444 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
445 return;
446 } else {
447 // Use Robin Hood hashing to minimize the worst case search.
448 // Also, every permutation of the insertion sequence produces
449 // the same final Robin Hood hash table, provided that a
450 // consistent tie breaker is used.
451 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
452 if (existing_dist < dist
453 // This tie breaker ensures that the hash order is maintained.
454 || ((existing_dist == dist)
455 && (uintptr_t(existing) < uintptr_t(klass)))) {
456 Klass* tmp = secondaries->at(slot);
457 secondaries->at_put(slot, klass);
458 klass = tmp;
459 dist = existing_dist;
460 }
461 ++dist;
462 }
463 }
464 }
465
466 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
467 GrowableArray<Klass*>* primaries,
468 GrowableArray<Klass*>* secondaries,
469 uintx& bitmap, TRAPS) {
470 int new_length = primaries->length() + secondaries->length();
471 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
472
473 // Combine the two arrays into a metadata object to pack the array.
474 // The primaries are added in the reverse order, then the secondaries.
475 int fill_p = primaries->length();
476 for (int j = 0; j < fill_p; j++) {
477 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
478 }
479 for( int j = 0; j < secondaries->length(); j++ ) {
480 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
481 }
482 #ifdef ASSERT
483 // We must not copy any null placeholders left over from bootstrap.
484 for (int j = 0; j < secondary_supers->length(); j++) {
485 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
486 }
487 #endif
488
489 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
490 return secondary_supers;
491 }
492
493 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
494 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
495 }
496
497 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
498 uint8_t hash = k->hash_slot();
499 if (hash > 0) {
500 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
501 }
502 return 0;
503 }
504
505
506 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
507 if (k == nullptr) {
508 set_super(nullptr);
509 _primary_supers[0] = this;
510 assert(super_depth() == 0, "Object must already be initialized properly");
511 } else if (k != super() || k == vmClasses::Object_klass()) {
512 assert(super() == nullptr || super() == vmClasses::Object_klass(),
513 "initialize this only once to a non-trivial value");
514 set_super(k);
515 Klass* sup = k;
516 int sup_depth = sup->super_depth();
517 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
518 if (!can_be_primary_super_slow())
519 my_depth = primary_super_limit();
520 for (juint i = 0; i < my_depth; i++) {
521 _primary_supers[i] = sup->_primary_supers[i];
522 }
523 Klass* *super_check_cell;
524 if (my_depth < primary_super_limit()) {
525 _primary_supers[my_depth] = this;
526 super_check_cell = &_primary_supers[my_depth];
527 } else {
528 // Overflow of the primary_supers array forces me to be secondary.
529 super_check_cell = &_secondary_super_cache;
530 }
531 set_super_check_offset(u4((address)super_check_cell - (address) this));
532
533 #ifdef ASSERT
534 {
535 juint j = super_depth();
536 assert(j == my_depth, "computed accessor gets right answer");
537 Klass* t = this;
538 while (!t->can_be_primary_super()) {
539 t = t->super();
540 j = t->super_depth();
541 }
542 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
543 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
544 }
545 while (t != nullptr) {
546 assert(primary_super_of_depth(j) == t, "super list initialization");
547 t = t->super();
548 --j;
549 }
550 assert(j == (juint)-1, "correct depth count");
551 }
552 #endif
553 }
554
555 if (secondary_supers() == nullptr) {
556
557 // Now compute the list of secondary supertypes.
558 // Secondaries can occasionally be on the super chain,
559 // if the inline "_primary_supers" array overflows.
560 int extras = 0;
561 Klass* p;
562 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
563 ++extras;
564 }
565
566 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
567
568 // Compute the "real" non-extra secondaries.
569 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
570 if (secondaries == nullptr) {
571 // secondary_supers set by compute_secondary_supers
572 return;
573 }
574
575 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
576
577 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
578 int i; // Scan for overflow primaries being duplicates of 2nd'arys
579
580 // This happens frequently for very deeply nested arrays: the
581 // primary superclass chain overflows into the secondary. The
582 // secondary list contains the element_klass's secondaries with
583 // an extra array dimension added. If the element_klass's
584 // secondary list already contains some primary overflows, they
585 // (with the extra level of array-ness) will collide with the
586 // normal primary superclass overflows.
587 for( i = 0; i < secondaries->length(); i++ ) {
588 if( secondaries->at(i) == p )
589 break;
590 }
591 if( i < secondaries->length() )
592 continue; // It's a dup, don't put it in
593 primaries->push(p);
594 }
595 // Combine the two arrays into a metadata object to pack the array.
596 uintx bitmap = 0;
597 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
598 set_secondary_supers(s2, bitmap);
599 }
600 }
601
602 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
603 Array<InstanceKlass*>* transitive_interfaces) {
604 assert(num_extra_slots == 0, "override for complex klasses");
605 assert(transitive_interfaces == nullptr, "sanity");
606 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
607 return nullptr;
608 }
609
610
611 // subklass links. Used by the compiler (and vtable initialization)
612 // May be cleaned concurrently, so must use the Compile_lock.
613 Klass* Klass::subklass() const {
614 // Need load_acquire on the _subklass, because it races with inserts that
615 // publishes freshly initialized data.
616 for (Klass* chain = AtomicAccess::load_acquire(&_subklass);
617 chain != nullptr;
618 // Do not need load_acquire on _next_sibling, because inserts never
619 // create _next_sibling edges to dead data.
620 chain = AtomicAccess::load(&chain->_next_sibling))
621 {
622 if (chain->is_loader_alive()) {
623 return chain;
624 }
625 }
626 return nullptr;
627 }
628
629 Klass* Klass::next_sibling(bool log) const {
630 // Do not need load_acquire on _next_sibling, because inserts never
631 // create _next_sibling edges to dead data.
632 for (Klass* chain = AtomicAccess::load(&_next_sibling);
633 chain != nullptr;
634 chain = AtomicAccess::load(&chain->_next_sibling)) {
635 // Only return alive klass, there may be stale klass
636 // in this chain if cleaned concurrently.
637 if (chain->is_loader_alive()) {
638 return chain;
639 } else if (log) {
640 if (log_is_enabled(Trace, class, unload)) {
641 ResourceMark rm;
642 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
643 }
644 }
645 }
646 return nullptr;
647 }
648
649 void Klass::set_subklass(Klass* s) {
650 assert(s != this, "sanity check");
651 AtomicAccess::release_store(&_subklass, s);
652 }
653
654 void Klass::set_next_sibling(Klass* s) {
655 assert(s != this, "sanity check");
656 // Does not need release semantics. If used by cleanup, it will link to
657 // already safely published data, and if used by inserts, will be published
658 // safely using cmpxchg.
659 AtomicAccess::store(&_next_sibling, s);
660 }
661
662 void Klass::append_to_sibling_list() {
663 if (Universe::is_fully_initialized()) {
664 assert_locked_or_safepoint(Compile_lock);
665 }
666 DEBUG_ONLY(verify();)
667 // add ourselves to super' subklass list
668 InstanceKlass* super = java_super();
669 if (super == nullptr) return; // special case: class Object
670 assert((!super->is_interface() // interfaces cannot be supers
671 && (super->java_super() == nullptr || !is_interface())),
672 "an interface can only be a subklass of Object");
673
674 // Make sure there is no stale subklass head
675 super->clean_subklass();
676
677 for (;;) {
678 Klass* prev_first_subklass = AtomicAccess::load_acquire(&_super->_subklass);
679 if (prev_first_subklass != nullptr) {
680 // set our sibling to be the super' previous first subklass
681 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
682 set_next_sibling(prev_first_subklass);
683 }
684 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
685 // are ever created to not alive klasses. This is an important invariant of the lock-free
686 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
687 if (AtomicAccess::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
688 return;
689 }
690 }
691 DEBUG_ONLY(verify();)
692 }
693
694 // The log parameter is for clean_weak_klass_links to report unlinked classes.
695 Klass* Klass::clean_subklass(bool log) {
696 for (;;) {
697 // Need load_acquire, due to contending with concurrent inserts
698 Klass* subklass = AtomicAccess::load_acquire(&_subklass);
699 if (subklass == nullptr || subklass->is_loader_alive()) {
700 return subklass;
701 }
702 if (log && log_is_enabled(Trace, class, unload)) {
703 ResourceMark rm;
704 log_trace(class, unload)("unlinking class (subclass): %s", subklass->external_name());
705 }
706 // Try to fix _subklass until it points at something not dead.
707 AtomicAccess::cmpxchg(&_subklass, subklass, subklass->next_sibling(log));
708 }
709 }
710
711 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
712 if (!ClassUnloading || !unloading_occurred) {
713 return;
714 }
715
716 Klass* root = vmClasses::Object_klass();
717 Stack<Klass*, mtGC> stack;
718
719 stack.push(root);
720 while (!stack.is_empty()) {
721 Klass* current = stack.pop();
722
723 assert(current->is_loader_alive(), "just checking, this should be live");
724
725 // Find and set the first alive subklass
726 Klass* sub = current->clean_subklass(true);
727 if (sub != nullptr) {
728 stack.push(sub);
729 }
730
731 // Find and set the first alive sibling
732 Klass* sibling = current->next_sibling(true);
733 current->set_next_sibling(sibling);
734 if (sibling != nullptr) {
735 stack.push(sibling);
736 }
737
738 // Clean the implementors list and method data.
739 if (clean_alive_klasses && current->is_instance_klass()) {
740 InstanceKlass* ik = InstanceKlass::cast(current);
741 clean_weak_instanceklass_links(ik);
742 }
743 }
744 }
745
746 void Klass::clean_weak_instanceklass_links(InstanceKlass* ik) {
747 ik->clean_weak_instanceklass_links();
748 // JVMTI RedefineClasses creates previous versions that are not in
749 // the class hierarchy, so process them here.
750 while ((ik = ik->previous_versions()) != nullptr) {
751 ik->clean_weak_instanceklass_links();
752 }
753 }
754
755 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
756 if (log_is_enabled(Trace, aot)) {
757 ResourceMark rm;
758 log_trace(aot)("Iter(Klass): %p (%s)", this, external_name());
759 }
760
761 it->push(&_name);
762 it->push(&_secondary_supers);
763 for (int i = 0; i < _primary_super_limit; i++) {
764 it->push(&_primary_supers[i]);
765 }
766 it->push(&_super);
767 if (!CDSConfig::is_dumping_archive()) {
768 // If dumping archive, these may point to excluded classes. There's no need
769 // to follow these pointers anyway, as they will be set to null in
770 // remove_unshareable_info().
771 it->push((Klass**)&_subklass);
772 it->push((Klass**)&_next_sibling);
773 it->push(&_next_link);
774 }
775
776 vtableEntry* vt = start_of_vtable();
777 for (int i=0; i<vtable_length(); i++) {
778 it->push(vt[i].method_addr());
779 }
780 }
781
782 #if INCLUDE_CDS
783 void Klass::remove_unshareable_info() {
784 assert(CDSConfig::is_dumping_archive(),
785 "only called during CDS dump time");
786 JFR_ONLY(REMOVE_ID(this);)
787 if (log_is_enabled(Trace, aot, unshareable)) {
788 ResourceMark rm;
789 log_trace(aot, unshareable)("remove: %s", external_name());
790 }
791
792 // _secondary_super_cache may be updated by an is_subtype_of() call
793 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
794 // null and let it be repopulated at runtime.
795 set_secondary_super_cache(nullptr);
796
797 set_subklass(nullptr);
798 set_next_sibling(nullptr);
799 set_next_link(nullptr);
800
801 // Null out class_loader_data because we don't share that yet.
802 set_class_loader_data(nullptr);
803 set_in_aot_cache();
804
805 if (CDSConfig::is_dumping_classic_static_archive()) {
806 // "Classic" static archives are required to have deterministic contents.
807 // The elements in _secondary_supers are addresses in the ArchiveBuilder
808 // output buffer, so they should have deterministic values. If we rehash
809 // _secondary_supers, its elements will appear in a deterministic order.
810 //
811 // Note that the bitmap is guaranteed to be deterministic, regardless of the
812 // actual addresses of the elements in _secondary_supers. So rehashing shouldn't
813 // change it.
814 uintx bitmap = hash_secondary_supers(secondary_supers(), true);
815 assert(bitmap == _secondary_supers_bitmap, "bitmap should not be changed due to rehashing");
816 }
817 }
818
819 void Klass::remove_java_mirror() {
820 assert(CDSConfig::is_dumping_archive(), "sanity");
821 if (log_is_enabled(Trace, aot, unshareable)) {
822 ResourceMark rm;
823 log_trace(aot, unshareable)("remove java_mirror: %s", external_name());
824 }
825
826 #if INCLUDE_CDS_JAVA_HEAP
827 _archived_mirror_index = -1;
828 if (CDSConfig::is_dumping_heap()) {
829 Klass* src_k = ArchiveBuilder::current()->get_source_addr(this);
830 oop orig_mirror = src_k->java_mirror();
831 if (orig_mirror == nullptr) {
832 assert(CDSConfig::is_dumping_final_static_archive(), "sanity");
833 if (is_instance_klass()) {
834 assert(InstanceKlass::cast(this)->defined_by_other_loaders(), "sanity");
835 } else {
836 precond(is_objArray_klass());
837 Klass *k = ObjArrayKlass::cast(this)->bottom_klass();
838 precond(k->is_instance_klass());
839 assert(InstanceKlass::cast(k)->defined_by_other_loaders(), "sanity");
840 }
841 } else {
842 oop scratch_mirror = HeapShared::scratch_java_mirror(orig_mirror);
843 if (scratch_mirror != nullptr) {
844 _archived_mirror_index = HeapShared::append_root(scratch_mirror);
845 }
846 }
847 }
848 #endif
849
850 // Just null out the mirror. The class_loader_data() no longer exists.
851 clear_java_mirror_handle();
852 }
853
854 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
855 assert(is_klass(), "ensure C++ vtable is restored");
856 assert(in_aot_cache(), "must be set");
857 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be");
858 if (log_is_enabled(Trace, aot, unshareable)) {
859 ResourceMark rm(THREAD);
860 oop class_loader = loader_data->class_loader();
861 log_trace(aot, unshareable)("restore: %s with class loader: %s", external_name(),
862 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
863 }
864
865 // If an exception happened during CDS restore, some of these fields may already be
866 // set. We leave the class on the CLD list, even if incomplete so that we don't
867 // modify the CLD list outside a safepoint.
868 if (class_loader_data() == nullptr) {
869 set_class_loader_data(loader_data);
870 }
871
872 // Add to class loader list first before creating the mirror
873 // (same order as class file parsing)
874 loader_data->add_class(this);
875
876 JFR_ONLY(Jfr::on_restoration(this, THREAD);)
877
878 Handle loader(THREAD, loader_data->class_loader());
879 ModuleEntry* module_entry = nullptr;
880 Klass* k = this;
881 if (k->is_objArray_klass()) {
882 k = ObjArrayKlass::cast(k)->bottom_klass();
883 }
884 // Obtain klass' module.
885 if (k->is_instance_klass()) {
886 InstanceKlass* ik = (InstanceKlass*) k;
887 module_entry = ik->module();
888 } else {
889 module_entry = ModuleEntryTable::javabase_moduleEntry();
890 }
891 // Obtain java.lang.Module, if available
892 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module_oop() : (oop)nullptr));
893
894 if (this->has_archived_mirror_index()) {
895 ResourceMark rm(THREAD);
896 log_debug(aot, mirror)("%s has raw archived mirror", external_name());
897 if (HeapShared::is_archived_heap_in_use()) {
898 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
899 protection_domain,
900 CHECK);
901 if (present) {
902 return;
903 }
904 }
905
906 // No archived mirror data
907 log_debug(aot, mirror)("No archived mirror data for %s", external_name());
908 clear_java_mirror_handle();
909 this->clear_archived_mirror_index();
910 }
911
912 // Only recreate it if not present. A previous attempt to restore may have
913 // gotten an OOM later but keep the mirror if it was created.
914 if (java_mirror() == nullptr) {
915 ResourceMark rm(THREAD);
916 log_trace(aot, mirror)("Recreate mirror for %s", external_name());
917 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
918 }
919 }
920 #endif // INCLUDE_CDS
921
922 #if INCLUDE_CDS_JAVA_HEAP
923 oop Klass::archived_java_mirror() {
924 assert(has_archived_mirror_index(), "must have archived mirror");
925 return HeapShared::get_root(_archived_mirror_index);
926 }
927
928 void Klass::clear_archived_mirror_index() {
929 if (_archived_mirror_index >= 0) {
930 HeapShared::clear_root(_archived_mirror_index);
931 }
932 _archived_mirror_index = -1;
933 }
934 #endif // INCLUDE_CDS_JAVA_HEAP
935
936 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
937 if (length > max_length) {
938 if (!THREAD->is_in_internal_oome_mark()) {
939 report_java_out_of_memory("Requested array size exceeds VM limit");
940 JvmtiExport::post_array_size_exhausted();
941 THROW_OOP(Universe::out_of_memory_error_array_size());
942 } else {
943 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
944 }
945 } else if (length < 0) {
946 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
947 }
948 }
949
950 // Replace the last '+' char with '/'.
951 static char* convert_hidden_name_to_java(Symbol* name) {
952 size_t name_len = name->utf8_length();
953 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
954 name->as_klass_external_name(result, (int)name_len + 1);
955 for (int index = (int)name_len; index > 0; index--) {
956 if (result[index] == '+') {
957 result[index] = JVM_SIGNATURE_SLASH;
958 break;
959 }
960 }
961 return result;
962 }
963
964 // In product mode, this function doesn't have virtual function calls so
965 // there might be some performance advantage to handling InstanceKlass here.
966 const char* Klass::external_name() const {
967 if (is_instance_klass()) {
968 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
969 if (ik->is_hidden()) {
970 char* result = convert_hidden_name_to_java(name());
971 return result;
972 }
973 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
974 char* result = convert_hidden_name_to_java(name());
975 return result;
976 }
977 if (name() == nullptr) return "<unknown>";
978 return name()->as_klass_external_name();
979 }
980
981 const char* Klass::signature_name() const {
982 if (name() == nullptr) return "<unknown>";
983 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
984 size_t name_len = name()->utf8_length();
985 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
986 name()->as_C_string(result, (int)name_len + 1);
987 for (int index = (int)name_len; index > 0; index--) {
988 if (result[index] == '+') {
989 result[index] = JVM_SIGNATURE_DOT;
990 break;
991 }
992 }
993 return result;
994 }
995 return name()->as_C_string();
996 }
997
998 const char* Klass::external_kind() const {
999 if (is_interface()) return "interface";
1000 if (is_abstract()) return "abstract class";
1001 return "class";
1002 }
1003
1004 // Unless overridden, jvmti_class_status has no flags set.
1005 jint Klass::jvmti_class_status() const {
1006 return 0;
1007 }
1008
1009
1010 // Printing
1011
1012 void Klass::print_on(outputStream* st) const {
1013 ResourceMark rm;
1014 // print title
1015 st->print("%s", internal_name());
1016 print_address_on(st);
1017 st->cr();
1018 }
1019
1020 #define BULLET " - "
1021
1022 // Caller needs ResourceMark
1023 void Klass::oop_print_on(oop obj, outputStream* st) {
1024 // print title
1025 st->print_cr("%s ", internal_name());
1026 obj->print_address_on(st);
1027
1028 if (WizardMode) {
1029 // print header
1030 obj->mark().print_on(st);
1031 st->cr();
1032 if (UseCompactObjectHeaders) {
1033 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
1034 st->cr();
1035 }
1036 }
1037
1038 // print class
1039 st->print(BULLET"klass: ");
1040 obj->klass()->print_value_on(st);
1041 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr();
1042 st->cr();
1043 }
1044
1045 void Klass::oop_print_value_on(oop obj, outputStream* st) {
1046 // print title
1047 ResourceMark rm; // Cannot print in debug mode without this
1048 st->print("%s", internal_name());
1049 obj->print_address_on(st);
1050 }
1051
1052 // Verification
1053
1054 void Klass::verify_on(outputStream* st) {
1055
1056 // This can be expensive, but it is worth checking that this klass is actually
1057 // in the CLD graph but not in production.
1058 #ifdef ASSERT
1059 if (UseCompressedClassPointers) {
1060 // Stricter checks for both correct alignment and placement
1061 CompressedKlassPointers::check_encodable(this);
1062 } else {
1063 assert(Metaspace::contains((address)this), "Should be");
1064 }
1065 #endif // ASSERT
1066
1067 guarantee(this->is_klass(),"should be klass");
1068
1069 if (super() != nullptr) {
1070 guarantee(super()->is_klass(), "should be klass");
1071 }
1072 if (secondary_super_cache() != nullptr) {
1073 Klass* ko = secondary_super_cache();
1074 guarantee(ko->is_klass(), "should be klass");
1075 }
1076 for ( uint i = 0; i < primary_super_limit(); i++ ) {
1077 Klass* ko = _primary_supers[i];
1078 if (ko != nullptr) {
1079 guarantee(ko->is_klass(), "should be klass");
1080 }
1081 }
1082
1083 if (java_mirror_no_keepalive() != nullptr) {
1084 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
1085 }
1086 }
1087
1088 void Klass::oop_verify_on(oop obj, outputStream* st) {
1089 guarantee(oopDesc::is_oop(obj), "should be oop");
1090 guarantee(obj->klass()->is_klass(), "klass field is not a klass");
1091 }
1092
1093 // Note: this function is called with an address that may or may not be a Klass.
1094 // The point is not to assert it is but to check if it could be.
1095 bool Klass::is_valid(Klass* k) {
1096 if (!is_aligned(k, sizeof(MetaWord))) return false;
1097 if ((size_t)k < os::min_page_size()) return false;
1098
1099 if (!os::is_readable_range(k, k + 1)) return false;
1100 if (!Metaspace::contains(k)) return false;
1101
1102 if (!Symbol::is_valid(k->name())) return false;
1103 return ClassLoaderDataGraph::is_valid(k->class_loader_data());
1104 }
1105
1106 Method* Klass::method_at_vtable(int index) {
1107 #ifndef PRODUCT
1108 assert(index >= 0, "valid vtable index");
1109 if (DebugVtables) {
1110 verify_vtable_index(index);
1111 }
1112 #endif
1113 return start_of_vtable()[index].method();
1114 }
1115
1116
1117 #ifndef PRODUCT
1118
1119 bool Klass::verify_vtable_index(int i) {
1120 int limit = vtable_length()/vtableEntry::size();
1121 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
1122 return true;
1123 }
1124
1125 #endif // PRODUCT
1126
1127 // Caller needs ResourceMark
1128 // joint_in_module_of_loader provides an optimization if 2 classes are in
1129 // the same module to succinctly print out relevant information about their
1130 // module name and class loader's name_and_id for error messages.
1131 // Format:
1132 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
1133 // are in module <module-name>[@<version>]
1134 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1135 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
1136 assert(module() == class2->module(), "classes do not have the same module");
1137 const char* class1_name = external_name();
1138 size_t len = strlen(class1_name) + 1;
1139
1140 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
1141 len += strlen(class2_description);
1142
1143 len += strlen(" and ");
1144
1145 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1146
1147 // Just return the FQN if error when allocating string
1148 if (joint_description == nullptr) {
1149 return class1_name;
1150 }
1151
1152 jio_snprintf(joint_description, len, "%s and %s",
1153 class1_name,
1154 class2_description);
1155
1156 return joint_description;
1157 }
1158
1159 // Caller needs ResourceMark
1160 // class_in_module_of_loader provides a standard way to include
1161 // relevant information about a class, such as its module name as
1162 // well as its class loader's name_and_id, in error messages and logging.
1163 // Format:
1164 // <fully-qualified-external-class-name> is in module <module-name>[@<version>]
1165 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1166 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
1167 // 1. fully qualified external name of class
1168 const char* klass_name = external_name();
1169 size_t len = strlen(klass_name) + 1;
1170
1171 // 2. module name + @version
1172 const char* module_name = "";
1173 const char* version = "";
1174 bool has_version = false;
1175 bool module_is_named = false;
1176 const char* module_name_phrase = "";
1177 const Klass* bottom_klass = is_objArray_klass() ?
1178 ObjArrayKlass::cast(this)->bottom_klass() : this;
1179 if (bottom_klass->is_instance_klass()) {
1180 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
1181 if (module->is_named()) {
1182 module_is_named = true;
1183 module_name_phrase = "module ";
1184 module_name = module->name()->as_C_string();
1185 len += strlen(module_name);
1186 // Use version if exists and is not a jdk module
1187 if (module->should_show_version()) {
1188 has_version = true;
1189 version = module->version()->as_C_string();
1190 // Include stlen(version) + 1 for the "@"
1191 len += strlen(version) + 1;
1192 }
1193 } else {
1194 module_name = UNNAMED_MODULE;
1195 len += UNNAMED_MODULE_LEN;
1196 }
1197 } else {
1198 // klass is an array of primitives, module is java.base
1199 module_is_named = true;
1200 module_name_phrase = "module ";
1201 module_name = JAVA_BASE_NAME;
1202 len += JAVA_BASE_NAME_LEN;
1203 }
1204
1205 // 3. class loader's name_and_id
1206 ClassLoaderData* cld = class_loader_data();
1207 assert(cld != nullptr, "class_loader_data should not be null");
1208 const char* loader_name_and_id = cld->loader_name_and_id();
1209 len += strlen(loader_name_and_id);
1210
1211 // 4. include parent loader information
1212 const char* parent_loader_phrase = "";
1213 const char* parent_loader_name_and_id = "";
1214 if (include_parent_loader &&
1215 !cld->is_builtin_class_loader_data()) {
1216 oop parent_loader = java_lang_ClassLoader::parent(class_loader());
1217 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
1218 // The parent loader's ClassLoaderData could be null if it is
1219 // a delegating class loader that has never defined a class.
1220 // In this case the loader's name must be obtained via the parent loader's oop.
1221 if (parent_cld == nullptr) {
1222 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
1223 if (cl_name_and_id != nullptr) {
1224 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
1225 }
1226 } else {
1227 parent_loader_name_and_id = parent_cld->loader_name_and_id();
1228 }
1229 parent_loader_phrase = ", parent loader ";
1230 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
1231 }
1232
1233 // Start to construct final full class description string
1234 len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
1235 len += strlen(module_name_phrase) + strlen(" of loader ");
1236
1237 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1238
1239 // Just return the FQN if error when allocating string
1240 if (class_description == nullptr) {
1241 return klass_name;
1242 }
1243
1244 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
1245 klass_name,
1246 (use_are) ? "are" : "is",
1247 module_name_phrase,
1248 module_name,
1249 (has_version) ? "@" : "",
1250 (has_version) ? version : "",
1251 loader_name_and_id,
1252 parent_loader_phrase,
1253 parent_loader_name_and_id);
1254
1255 return class_description;
1256 }
1257
1258 class LookupStats : StackObj {
1259 private:
1260 uint _no_of_samples;
1261 uint _worst;
1262 uint _worst_count;
1263 uint _average;
1264 uint _best;
1265 uint _best_count;
1266 public:
1267 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {}
1268
1269 ~LookupStats() {
1270 assert(_best <= _worst || _no_of_samples == 0, "sanity");
1271 }
1272
1273 void sample(uint value) {
1274 ++_no_of_samples;
1275 _average += value;
1276
1277 if (_worst < value) {
1278 _worst = value;
1279 _worst_count = 1;
1280 } else if (_worst == value) {
1281 ++_worst_count;
1282 }
1283
1284 if (_best > value) {
1285 _best = value;
1286 _best_count = 1;
1287 } else if (_best == value) {
1288 ++_best_count;
1289 }
1290 }
1291
1292 void print_on(outputStream* st) const {
1293 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples);
1294 if (_best_count < _no_of_samples) {
1295 st->print("; average: %4.1f; worst: %2d (%4.1f%%)",
1296 (1.0 * _average) / _no_of_samples,
1297 _worst, (100.0 * _worst_count) / _no_of_samples);
1298 }
1299 }
1300 };
1301
1302 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) {
1303 int num_of_supers = secondary_supers->length();
1304
1305 LookupStats s;
1306 for (int i = 0; i < num_of_supers; i++) {
1307 Klass* secondary_super = secondary_supers->at(i);
1308 int home_slot = Klass::compute_home_slot(secondary_super, bitmap);
1309 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK);
1310 s.sample(score);
1311 }
1312 st->print("positive_lookup: "); s.print_on(st);
1313 }
1314
1315 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) {
1316 assert(~bitmap != 0, "no zeroes");
1317 uintx start = rotate_right(bitmap, slot);
1318 return count_trailing_zeros(~start);
1319 }
1320
1321 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) {
1322 LookupStats s;
1323 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
1324 uint score = compute_distance_to_nearest_zero(slot, bitmap);
1325 s.sample(score);
1326 }
1327 st->print("negative_lookup: "); s.print_on(st);
1328 }
1329
1330 void Klass::print_secondary_supers_on(outputStream* st) const {
1331 if (secondary_supers() != nullptr) {
1332 st->print(" - "); st->print("%d elements;", _secondary_supers->length());
1333 st->print_cr(" bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap);
1334 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY &&
1335 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) {
1336 st->print(" - "); print_positive_lookup_stats(secondary_supers(),
1337 _secondary_supers_bitmap, st); st->cr();
1338 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr();
1339 }
1340 } else {
1341 st->print("null");
1342 }
1343 }
1344
1345 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) {
1346 ResourceMark rm;
1347 super->print();
1348 sub->print();
1349 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d",
1350 msg, sub->external_name(), super->external_name(), linear_result, table_result);
1351 }
--- EOF ---