1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/archiveHeapLoader.hpp"
27 #include "cds/cdsConfig.hpp"
28 #include "cds/heapShared.hpp"
29 #include "classfile/classLoader.hpp"
30 #include "classfile/classLoaderData.inline.hpp"
31 #include "classfile/classLoaderDataGraph.inline.hpp"
32 #include "classfile/javaClasses.inline.hpp"
33 #include "classfile/moduleEntry.hpp"
34 #include "classfile/systemDictionary.hpp"
35 #include "classfile/systemDictionaryShared.hpp"
36 #include "classfile/vmClasses.hpp"
37 #include "classfile/vmSymbols.hpp"
38 #include "gc/shared/collectedHeap.inline.hpp"
39 #include "jvm_io.h"
40 #include "logging/log.hpp"
41 #include "memory/metadataFactory.hpp"
42 #include "memory/metaspaceClosure.hpp"
43 #include "memory/oopFactory.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "memory/universe.hpp"
46 #include "oops/compressedKlass.inline.hpp"
47 #include "oops/compressedOops.inline.hpp"
48 #include "oops/instanceKlass.hpp"
49 #include "oops/klass.inline.hpp"
50 #include "oops/objArrayKlass.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/oopHandle.inline.hpp"
53 #include "prims/jvmtiExport.hpp"
54 #include "runtime/atomic.hpp"
55 #include "runtime/handles.inline.hpp"
56 #include "runtime/perfData.hpp"
57 #include "utilities/macros.hpp"
58 #include "utilities/powerOfTwo.hpp"
59 #include "utilities/rotate_bits.hpp"
60 #include "utilities/stack.inline.hpp"
61
62 void Klass::set_java_mirror(Handle m) {
63 assert(!m.is_null(), "New mirror should never be null.");
64 assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
65 _java_mirror = class_loader_data()->add_handle(m);
66 }
67
68 bool Klass::is_cloneable() const {
69 return _misc_flags.is_cloneable_fast() ||
70 is_subtype_of(vmClasses::Cloneable_klass());
71 }
72
73 void Klass::set_is_cloneable() {
74 if (name() == vmSymbols::java_lang_invoke_MemberName()) {
75 assert(is_final(), "no subclasses allowed");
76 // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
77 } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
78 // Reference cloning should not be intrinsified and always happen in JVM_Clone.
79 } else {
80 _misc_flags.set_is_cloneable_fast(true);
81 }
82 }
83
84 uint8_t Klass::compute_hash_slot(Symbol* n) {
85 uint hash_code;
86 // Special cases for the two superclasses of all Array instances.
87 // Code elsewhere assumes, for all instances of ArrayKlass, that
88 // these two interfaces will be in this order.
89
90 // We ensure there are some empty slots in the hash table between
91 // these two very common interfaces because if they were adjacent
92 // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1
93 // would result in a probe length of 3.
94 if (n == vmSymbols::java_lang_Cloneable()) {
95 hash_code = 0;
96 } else if (n == vmSymbols::java_io_Serializable()) {
97 hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2;
98 } else {
99 auto s = (const jbyte*) n->bytes();
100 hash_code = java_lang_String::hash_code(s, n->utf8_length());
101 // We use String::hash_code here (rather than e.g.
102 // Symbol::identity_hash()) in order to have a hash code that
103 // does not change from run to run. We want that because the
104 // hash value for a secondary superclass appears in generated
105 // code as a constant.
106
107 // This constant is magic: see Knuth, "Fibonacci Hashing".
108 constexpr uint multiplier
109 = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 ))
110 constexpr uint hash_shift = sizeof(hash_code) * 8 - 6;
111 // The leading bits of the least significant half of the product.
112 hash_code = (hash_code * multiplier) >> hash_shift;
113
114 if (StressSecondarySupers) {
115 // Generate many hash collisions in order to stress-test the
116 // linear search fallback.
117 hash_code = hash_code % 3;
118 hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3);
119 }
120 }
121
122 return (hash_code & SECONDARY_SUPERS_TABLE_MASK);
123 }
124
125 void Klass::set_name(Symbol* n) {
126 _name = n;
127
128 if (_name != nullptr) {
129 _name->increment_refcount();
130 }
131
132 {
133 elapsedTimer selftime;
134 selftime.start();
135
136 _hash_slot = compute_hash_slot(n);
137 assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required");
138
139 selftime.stop();
140 if (UsePerfData) {
141 ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks());
142 }
143 }
144
145 if (CDSConfig::is_dumping_archive() && is_instance_klass()) {
146 SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
147 }
148 }
149
150 bool Klass::is_subclass_of(const Klass* k) const {
151 // Run up the super chain and check
152 if (this == k) return true;
153
154 Klass* t = const_cast<Klass*>(this)->super();
155
156 while (t != nullptr) {
157 if (t == k) return true;
158 t = t->super();
159 }
160 return false;
161 }
162
163 void Klass::release_C_heap_structures(bool release_constant_pool) {
164 if (_name != nullptr) _name->decrement_refcount();
165 }
166
167 bool Klass::linear_search_secondary_supers(const Klass* k) const {
168 // Scan the array-of-objects for a match
169 // FIXME: We could do something smarter here, maybe a vectorized
170 // comparison or a binary search, but is that worth any added
171 // complexity?
172 int cnt = secondary_supers()->length();
173 for (int i = 0; i < cnt; i++) {
174 if (secondary_supers()->at(i) == k) {
175 return true;
176 }
177 }
178 return false;
179 }
180
181 // Given a secondary superklass k, an initial array index, and an
182 // occupancy bitmap rotated such that Bit 1 is the next bit to test,
183 // search for k.
184 bool Klass::fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const {
185 // Once the occupancy bitmap is almost full, it's faster to use a
186 // linear search.
187 if (secondary_supers()->length() > SECONDARY_SUPERS_TABLE_SIZE - 2) {
188 return linear_search_secondary_supers(k);
189 }
190
191 // This is conventional linear probing, but instead of terminating
192 // when a null entry is found in the table, we maintain a bitmap
193 // in which a 0 indicates missing entries.
194
195 precond((int)population_count(rotated_bitmap) == secondary_supers()->length());
196
197 // The check for secondary_supers()->length() <= SECONDARY_SUPERS_TABLE_SIZE - 2
198 // at the start of this function guarantees there are 0s in the
199 // bitmap, so this loop eventually terminates.
200 while ((rotated_bitmap & 2) != 0) {
201 if (++index == secondary_supers()->length()) {
202 index = 0;
203 }
204 if (secondary_supers()->at(index) == k) {
205 return true;
206 }
207 rotated_bitmap = rotate_right(rotated_bitmap, 1);
208 }
209 return false;
210 }
211
212 // Return self, except for abstract classes with exactly 1
213 // implementor. Then return the 1 concrete implementation.
214 Klass *Klass::up_cast_abstract() {
215 Klass *r = this;
216 while( r->is_abstract() ) { // Receiver is abstract?
217 Klass *s = r->subklass(); // Check for exactly 1 subklass
218 if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up
219 return this; // Return 'this' as a no-progress flag
220 r = s; // Loop till find concrete class
221 }
222 return r; // Return the 1 concrete class
223 }
224
225 // Find LCA in class hierarchy
226 Klass *Klass::LCA( Klass *k2 ) {
227 Klass *k1 = this;
228 while( 1 ) {
229 if( k1->is_subtype_of(k2) ) return k2;
230 if( k2->is_subtype_of(k1) ) return k1;
231 k1 = k1->super();
232 k2 = k2->super();
233 }
234 }
235
236
237 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
238 ResourceMark rm(THREAD);
239 THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
240 : vmSymbols::java_lang_InstantiationException(), external_name());
241 }
242
243
244 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
245 ResourceMark rm(THREAD);
246 assert(s != nullptr, "Throw NPE!");
247 THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
248 err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
249 }
250
251
252 void Klass::initialize(TRAPS) {
253 ShouldNotReachHere();
254 }
255
256 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
257 #ifdef ASSERT
258 tty->print_cr("Error: find_field called on a klass oop."
259 " Likely error: reflection method does not correctly"
260 " wrap return value in a mirror object.");
261 #endif
262 ShouldNotReachHere();
263 return nullptr;
264 }
265
266 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
267 OverpassLookupMode overpass_mode,
268 PrivateLookupMode private_mode) const {
269 #ifdef ASSERT
270 tty->print_cr("Error: uncached_lookup_method called on a klass oop."
271 " Likely error: reflection method does not correctly"
272 " wrap return value in a mirror object.");
273 #endif
274 ShouldNotReachHere();
275 return nullptr;
276 }
277
278 static markWord make_prototype(const Klass* kls) {
279 markWord prototype = markWord::prototype();
280 #ifdef _LP64
281 if (UseCompactObjectHeaders) {
282 // With compact object headers, the narrow Klass ID is part of the mark word.
283 // We therfore seed the mark word with the narrow Klass ID.
284 // Note that only those Klass that can be instantiated have a narrow Klass ID.
285 // For those who don't, we leave the klass bits empty and assert if someone
286 // tries to use those.
287 const narrowKlass nk = CompressedKlassPointers::is_encodable(kls) ?
288 CompressedKlassPointers::encode(const_cast<Klass*>(kls)) : 0;
289 prototype = prototype.set_narrow_klass(nk);
290 }
291 #endif
292 return prototype;
293 }
294
295 Klass::Klass() : _kind(UnknownKlassKind) {
296 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
297 }
298
299 // "Normal" instantiation is preceded by a MetaspaceObj allocation
300 // which zeros out memory - calloc equivalent.
301 // The constructor is also used from CppVtableCloner,
302 // which doesn't zero out the memory before calling the constructor.
303 Klass::Klass(KlassKind kind) : _kind(kind),
304 _prototype_header(make_prototype(this)),
305 _shared_class_path_index(-1) {
306 CDS_ONLY(_shared_class_flags = 0;)
307 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
308 _primary_supers[0] = this;
309 set_super_check_offset(in_bytes(primary_supers_offset()));
310 }
311
312 jint Klass::array_layout_helper(BasicType etype) {
313 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
314 // Note that T_ARRAY is not allowed here.
315 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
316 int esize = type2aelembytes(etype);
317 bool isobj = (etype == T_OBJECT);
318 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
319 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
320
321 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
322 assert(layout_helper_is_array(lh), "correct kind");
323 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
324 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
325 assert(layout_helper_header_size(lh) == hsize, "correct decode");
326 assert(layout_helper_element_type(lh) == etype, "correct decode");
327 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
328
329 return lh;
330 }
331
332 bool Klass::can_be_primary_super_slow() const {
333 if (super() == nullptr)
334 return true;
335 else if (super()->super_depth() >= primary_super_limit()-1)
336 return false;
337 else
338 return true;
339 }
340
341 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
342 #ifdef ASSERT
343 if (secondaries != nullptr) {
344 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
345 assert(bitmap == real_bitmap, "must be");
346 assert(secondaries->length() >= (int)population_count(bitmap), "must be");
347 }
348 #endif
349 _secondary_supers_bitmap = bitmap;
350 _secondary_supers = secondaries;
351
352 if (secondaries != nullptr) {
353 LogMessage(class, load) msg;
354 NonInterleavingLogStream log {LogLevel::Debug, msg};
355 if (log.is_enabled()) {
356 ResourceMark rm;
357 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
358 print_secondary_supers_on(&log);
359 }
360 }
361 }
362
363 // Hashed secondary superclasses
364 //
365 // We use a compressed 64-entry hash table with linear probing. We
366 // start by creating a hash table in the usual way, followed by a pass
367 // that removes all the null entries. To indicate which entries would
368 // have been null we use a bitmap that contains a 1 in each position
369 // where an entry is present, 0 otherwise. This bitmap also serves as
370 // a kind of Bloom filter, which in many cases allows us quickly to
371 // eliminate the possibility that something is a member of a set of
372 // secondaries.
373 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
374 const int length = secondaries->length();
375
376 if (length == 0) {
377 return SECONDARY_SUPERS_BITMAP_EMPTY;
378 }
379
380 if (length == 1) {
381 int hash_slot = secondaries->at(0)->hash_slot();
382 return uintx(1) << hash_slot;
383 }
384
385 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)
386
387 // Don't attempt to hash a table that's completely full, because in
388 // the case of an absent interface linear probing would not
389 // terminate.
390 if (length >= SECONDARY_SUPERS_TABLE_SIZE) {
391 return SECONDARY_SUPERS_BITMAP_FULL;
392 }
393
394 {
395 //PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time()); // Leyden FIXME
396
397 ResourceMark rm;
398 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
399 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
400 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
401
402 for (int j = 0; j < length; j++) {
403 Klass* k = secondaries->at(j);
404 hash_insert(k, hashed_secondaries, bitmap);
405 }
406
407 // Pack the hashed secondaries array by copying it into the
408 // secondaries array, sans nulls, if modification is allowed.
409 // Otherwise, validate the order.
410 int i = 0;
411 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
412 bool has_element = ((bitmap >> slot) & 1) != 0;
413 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
414 if (has_element) {
415 Klass* k = hashed_secondaries->at(slot);
416 if (rewrite) {
417 secondaries->at_put(i, k);
418 } else if (secondaries->at(i) != k) {
419 assert(false, "broken secondary supers hash table");
420 return SECONDARY_SUPERS_BITMAP_FULL;
421 }
422 i++;
423 }
424 }
425 assert(i == secondaries->length(), "mismatch");
426 postcond((int)population_count(bitmap) == secondaries->length());
427
428 return bitmap;
429 }
430 }
431
432 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
433 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
434
435 int dist = 0;
436 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
437 Klass* existing = secondaries->at(slot);
438 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
439 if (existing == nullptr) { // no conflict
440 secondaries->at_put(slot, klass);
441 bitmap |= uintx(1) << slot;
442 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
443 return;
444 } else {
445 // Use Robin Hood hashing to minimize the worst case search.
446 // Also, every permutation of the insertion sequence produces
447 // the same final Robin Hood hash table, provided that a
448 // consistent tie breaker is used.
449 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
450 if (existing_dist < dist
451 // This tie breaker ensures that the hash order is maintained.
452 || ((existing_dist == dist)
453 && (uintptr_t(existing) < uintptr_t(klass)))) {
454 Klass* tmp = secondaries->at(slot);
455 secondaries->at_put(slot, klass);
456 klass = tmp;
457 dist = existing_dist;
458 }
459 ++dist;
460 }
461 }
462 }
463
464 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
465 GrowableArray<Klass*>* primaries,
466 GrowableArray<Klass*>* secondaries,
467 uintx& bitmap, TRAPS) {
468 int new_length = primaries->length() + secondaries->length();
469 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
470
471 // Combine the two arrays into a metadata object to pack the array.
472 // The primaries are added in the reverse order, then the secondaries.
473 int fill_p = primaries->length();
474 for (int j = 0; j < fill_p; j++) {
475 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
476 }
477 for( int j = 0; j < secondaries->length(); j++ ) {
478 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
479 }
480 #ifdef ASSERT
481 // We must not copy any null placeholders left over from bootstrap.
482 for (int j = 0; j < secondary_supers->length(); j++) {
483 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
484 }
485 #endif
486
487 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
488 return secondary_supers;
489 }
490
491 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
492 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
493 }
494
495 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
496 uint8_t hash = k->hash_slot();
497 if (hash > 0) {
498 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
499 }
500 return 0;
501 }
502
503
504 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
505 if (k == nullptr) {
506 set_super(nullptr);
507 _primary_supers[0] = this;
508 assert(super_depth() == 0, "Object must already be initialized properly");
509 } else if (k != super() || k == vmClasses::Object_klass()) {
510 assert(super() == nullptr || super() == vmClasses::Object_klass(),
511 "initialize this only once to a non-trivial value");
512 set_super(k);
513 Klass* sup = k;
514 int sup_depth = sup->super_depth();
515 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
516 if (!can_be_primary_super_slow())
517 my_depth = primary_super_limit();
518 for (juint i = 0; i < my_depth; i++) {
519 _primary_supers[i] = sup->_primary_supers[i];
520 }
521 Klass* *super_check_cell;
522 if (my_depth < primary_super_limit()) {
523 _primary_supers[my_depth] = this;
524 super_check_cell = &_primary_supers[my_depth];
525 } else {
526 // Overflow of the primary_supers array forces me to be secondary.
527 super_check_cell = &_secondary_super_cache;
528 }
529 set_super_check_offset(u4((address)super_check_cell - (address) this));
530
531 #ifdef ASSERT
532 {
533 juint j = super_depth();
534 assert(j == my_depth, "computed accessor gets right answer");
535 Klass* t = this;
536 while (!t->can_be_primary_super()) {
537 t = t->super();
538 j = t->super_depth();
539 }
540 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
541 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
542 }
543 while (t != nullptr) {
544 assert(primary_super_of_depth(j) == t, "super list initialization");
545 t = t->super();
546 --j;
547 }
548 assert(j == (juint)-1, "correct depth count");
549 }
550 #endif
551 }
552
553 if (secondary_supers() == nullptr) {
554
555 // Now compute the list of secondary supertypes.
556 // Secondaries can occasionally be on the super chain,
557 // if the inline "_primary_supers" array overflows.
558 int extras = 0;
559 Klass* p;
560 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
561 ++extras;
562 }
563
564 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
565
566 // Compute the "real" non-extra secondaries.
567 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
568 if (secondaries == nullptr) {
569 // secondary_supers set by compute_secondary_supers
570 return;
571 }
572
573 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
574
575 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
576 int i; // Scan for overflow primaries being duplicates of 2nd'arys
577
578 // This happens frequently for very deeply nested arrays: the
579 // primary superclass chain overflows into the secondary. The
580 // secondary list contains the element_klass's secondaries with
581 // an extra array dimension added. If the element_klass's
582 // secondary list already contains some primary overflows, they
583 // (with the extra level of array-ness) will collide with the
584 // normal primary superclass overflows.
585 for( i = 0; i < secondaries->length(); i++ ) {
586 if( secondaries->at(i) == p )
587 break;
588 }
589 if( i < secondaries->length() )
590 continue; // It's a dup, don't put it in
591 primaries->push(p);
592 }
593 // Combine the two arrays into a metadata object to pack the array.
594 uintx bitmap = 0;
595 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
596 set_secondary_supers(s2, bitmap);
597 }
598 }
599
600 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
601 Array<InstanceKlass*>* transitive_interfaces) {
602 assert(num_extra_slots == 0, "override for complex klasses");
603 assert(transitive_interfaces == nullptr, "sanity");
604 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
605 return nullptr;
606 }
607
608
609 // superklass links
610 InstanceKlass* Klass::superklass() const {
611 assert(super() == nullptr || super()->is_instance_klass(), "must be instance klass");
612 return _super == nullptr ? nullptr : InstanceKlass::cast(_super);
613 }
614
615 // subklass links. Used by the compiler (and vtable initialization)
616 // May be cleaned concurrently, so must use the Compile_lock.
617 // The log parameter is for clean_weak_klass_links to report unlinked classes.
618 Klass* Klass::subklass(bool log) const {
619 // Need load_acquire on the _subklass, because it races with inserts that
620 // publishes freshly initialized data.
621 for (Klass* chain = Atomic::load_acquire(&_subklass);
622 chain != nullptr;
623 // Do not need load_acquire on _next_sibling, because inserts never
624 // create _next_sibling edges to dead data.
625 chain = Atomic::load(&chain->_next_sibling))
626 {
627 if (chain->is_loader_alive()) {
628 return chain;
629 } else if (log) {
630 if (log_is_enabled(Trace, class, unload)) {
631 ResourceMark rm;
632 log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
633 }
634 }
635 }
636 return nullptr;
637 }
638
639 Klass* Klass::next_sibling(bool log) const {
640 // Do not need load_acquire on _next_sibling, because inserts never
641 // create _next_sibling edges to dead data.
642 for (Klass* chain = Atomic::load(&_next_sibling);
643 chain != nullptr;
644 chain = Atomic::load(&chain->_next_sibling)) {
645 // Only return alive klass, there may be stale klass
646 // in this chain if cleaned concurrently.
647 if (chain->is_loader_alive()) {
648 return chain;
649 } else if (log) {
650 if (log_is_enabled(Trace, class, unload)) {
651 ResourceMark rm;
652 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
653 }
654 }
655 }
656 return nullptr;
657 }
658
659 void Klass::set_subklass(Klass* s) {
660 assert(s != this, "sanity check");
661 Atomic::release_store(&_subklass, s);
662 }
663
664 void Klass::set_next_sibling(Klass* s) {
665 assert(s != this, "sanity check");
666 // Does not need release semantics. If used by cleanup, it will link to
667 // already safely published data, and if used by inserts, will be published
668 // safely using cmpxchg.
669 Atomic::store(&_next_sibling, s);
670 }
671
672 void Klass::append_to_sibling_list() {
673 if (Universe::is_fully_initialized()) {
674 assert_locked_or_safepoint(Compile_lock);
675 }
676 debug_only(verify();)
677 // add ourselves to superklass' subklass list
678 InstanceKlass* super = superklass();
679 if (super == nullptr) return; // special case: class Object
680 assert((!super->is_interface() // interfaces cannot be supers
681 && (super->superklass() == nullptr || !is_interface())),
682 "an interface can only be a subklass of Object");
683
684 // Make sure there is no stale subklass head
685 super->clean_subklass();
686
687 for (;;) {
688 Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
689 if (prev_first_subklass != nullptr) {
690 // set our sibling to be the superklass' previous first subklass
691 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
692 set_next_sibling(prev_first_subklass);
693 }
694 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
695 // are ever created to not alive klasses. This is an important invariant of the lock-free
696 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
697 if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
698 return;
699 }
700 }
701 debug_only(verify();)
702 }
703
704 void Klass::clean_subklass() {
705 for (;;) {
706 // Need load_acquire, due to contending with concurrent inserts
707 Klass* subklass = Atomic::load_acquire(&_subklass);
708 if (subklass == nullptr || subklass->is_loader_alive()) {
709 return;
710 }
711 // Try to fix _subklass until it points at something not dead.
712 Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
713 }
714 }
715
716 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
717 if (!ClassUnloading || !unloading_occurred) {
718 return;
719 }
720
721 Klass* root = vmClasses::Object_klass();
722 Stack<Klass*, mtGC> stack;
723
724 stack.push(root);
725 while (!stack.is_empty()) {
726 Klass* current = stack.pop();
727
728 assert(current->is_loader_alive(), "just checking, this should be live");
729
730 // Find and set the first alive subklass
731 Klass* sub = current->subklass(true);
732 current->clean_subklass();
733 if (sub != nullptr) {
734 stack.push(sub);
735 }
736
737 // Find and set the first alive sibling
738 Klass* sibling = current->next_sibling(true);
739 current->set_next_sibling(sibling);
740 if (sibling != nullptr) {
741 stack.push(sibling);
742 }
743
744 // Clean the implementors list and method data.
745 if (clean_alive_klasses && current->is_instance_klass()) {
746 InstanceKlass* ik = InstanceKlass::cast(current);
747 ik->clean_weak_instanceklass_links();
748
749 // JVMTI RedefineClasses creates previous versions that are not in
750 // the class hierarchy, so process them here.
751 while ((ik = ik->previous_versions()) != nullptr) {
752 ik->clean_weak_instanceklass_links();
753 }
754 }
755 }
756 }
757
758 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
759 if (log_is_enabled(Trace, cds)) {
760 ResourceMark rm;
761 log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
762 }
763
764 it->push(&_name);
765 it->push(&_secondary_supers);
766 for (int i = 0; i < _primary_super_limit; i++) {
767 it->push(&_primary_supers[i]);
768 }
769 it->push(&_super);
770 if (!CDSConfig::is_dumping_archive()) {
771 // If dumping archive, these may point to excluded classes. There's no need
772 // to follow these pointers anyway, as they will be set to null in
773 // remove_unshareable_info().
774 it->push((Klass**)&_subklass);
775 it->push((Klass**)&_next_sibling);
776 it->push(&_next_link);
777 }
778
779 vtableEntry* vt = start_of_vtable();
780 for (int i=0; i<vtable_length(); i++) {
781 it->push(vt[i].method_addr());
782 }
783 }
784
785 #if INCLUDE_CDS
786 void Klass::remove_unshareable_info() {
787 assert(CDSConfig::is_dumping_archive(),
788 "only called during CDS dump time");
789 JFR_ONLY(REMOVE_ID(this);)
790 if (log_is_enabled(Trace, cds, unshareable)) {
791 ResourceMark rm;
792 log_trace(cds, unshareable)("remove: %s", external_name());
793 }
794
795 // _secondary_super_cache may be updated by an is_subtype_of() call
796 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
797 // null and let it be repopulated at runtime.
798 set_secondary_super_cache(nullptr);
799
800 set_subklass(nullptr);
801 set_next_sibling(nullptr);
802 set_next_link(nullptr);
803
804 // Null out class_loader_data because we don't share that yet.
805 set_class_loader_data(nullptr);
806 set_is_shared();
807
808 // FIXME: validation in Klass::hash_secondary_supers() may fail for shared klasses.
809 // Even though the bitmaps always match, the canonical order of elements in the table
810 // is not guaranteed to stay the same (see tie breaker during Robin Hood hashing in Klass::hash_insert).
811 //assert(compute_secondary_supers_bitmap(secondary_supers()) == _secondary_supers_bitmap, "broken table");
812 }
813
814 void Klass::remove_java_mirror() {
815 assert(CDSConfig::is_dumping_archive(), "sanity");
816 if (log_is_enabled(Trace, cds, unshareable)) {
817 ResourceMark rm;
818 log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
819 }
820 // Just null out the mirror. The class_loader_data() no longer exists.
821 clear_java_mirror_handle();
822 }
823
824 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
825 assert(is_klass(), "ensure C++ vtable is restored");
826 assert(is_shared(), "must be set");
827 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be");
828 JFR_ONLY(RESTORE_ID(this);)
829 if (log_is_enabled(Trace, cds, unshareable)) {
830 ResourceMark rm(THREAD);
831 oop class_loader = loader_data->class_loader();
832 log_trace(cds, unshareable)("restore: %s with class loader: %s", external_name(),
833 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
834 }
835
836 // If an exception happened during CDS restore, some of these fields may already be
837 // set. We leave the class on the CLD list, even if incomplete so that we don't
838 // modify the CLD list outside a safepoint.
839 if (class_loader_data() == nullptr) {
840 set_class_loader_data(loader_data);
841
842 // Add to class loader list first before creating the mirror
843 // (same order as class file parsing)
844 loader_data->add_class(this);
845 }
846
847 Handle loader(THREAD, loader_data->class_loader());
848 ModuleEntry* module_entry = nullptr;
849 Klass* k = this;
850 if (k->is_objArray_klass()) {
851 k = ObjArrayKlass::cast(k)->bottom_klass();
852 }
853 // Obtain klass' module.
854 if (k->is_instance_klass()) {
855 InstanceKlass* ik = (InstanceKlass*) k;
856 module_entry = ik->module();
857 } else {
858 module_entry = ModuleEntryTable::javabase_moduleEntry();
859 }
860 // Obtain java.lang.Module, if available
861 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module() : (oop)nullptr));
862
863 if (this->has_archived_mirror_index()) {
864 ResourceMark rm(THREAD);
865 log_debug(cds, mirror)("%s has raw archived mirror", external_name());
866 if (ArchiveHeapLoader::is_in_use()) {
867 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
868 protection_domain,
869 CHECK);
870 if (present) {
871 return;
872 }
873 }
874
875 // No archived mirror data
876 log_debug(cds, mirror)("No archived mirror data for %s", external_name());
877 clear_java_mirror_handle();
878 this->clear_archived_mirror_index();
879 }
880
881 // Only recreate it if not present. A previous attempt to restore may have
882 // gotten an OOM later but keep the mirror if it was created.
883 if (java_mirror() == nullptr) {
884 ResourceMark rm(THREAD);
885 log_trace(cds, mirror)("Recreate mirror for %s", external_name());
886 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
887 }
888 }
889 #endif // INCLUDE_CDS
890
891 #if INCLUDE_CDS_JAVA_HEAP
892 oop Klass::archived_java_mirror() {
893 assert(has_archived_mirror_index(), "must have archived mirror");
894 return HeapShared::get_root(_archived_mirror_index);
895 }
896
897 void Klass::clear_archived_mirror_index() {
898 if (_archived_mirror_index >= 0) {
899 HeapShared::clear_root(_archived_mirror_index);
900 }
901 _archived_mirror_index = -1;
902 }
903
904 // No GC barrier
905 void Klass::set_archived_java_mirror(int mirror_index) {
906 assert(CDSConfig::is_dumping_heap(), "sanity");
907 _archived_mirror_index = mirror_index;
908 }
909 #endif // INCLUDE_CDS_JAVA_HEAP
910
911 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
912 if (length > max_length) {
913 if (!THREAD->is_in_internal_oome_mark()) {
914 report_java_out_of_memory("Requested array size exceeds VM limit");
915 JvmtiExport::post_array_size_exhausted();
916 THROW_OOP(Universe::out_of_memory_error_array_size());
917 } else {
918 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
919 }
920 } else if (length < 0) {
921 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
922 }
923 }
924
925 // Replace the last '+' char with '/'.
926 static char* convert_hidden_name_to_java(Symbol* name) {
927 size_t name_len = name->utf8_length();
928 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
929 name->as_klass_external_name(result, (int)name_len + 1);
930 for (int index = (int)name_len; index > 0; index--) {
931 if (result[index] == '+') {
932 result[index] = JVM_SIGNATURE_SLASH;
933 break;
934 }
935 }
936 return result;
937 }
938
939 // In product mode, this function doesn't have virtual function calls so
940 // there might be some performance advantage to handling InstanceKlass here.
941 const char* Klass::external_name() const {
942 if (is_instance_klass()) {
943 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
944 if (ik->is_hidden()) {
945 char* result = convert_hidden_name_to_java(name());
946 return result;
947 }
948 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
949 char* result = convert_hidden_name_to_java(name());
950 return result;
951 }
952 if (name() == nullptr) return "<unknown>";
953 return name()->as_klass_external_name();
954 }
955
956 const char* Klass::signature_name() const {
957 if (name() == nullptr) return "<unknown>";
958 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
959 size_t name_len = name()->utf8_length();
960 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
961 name()->as_C_string(result, (int)name_len + 1);
962 for (int index = (int)name_len; index > 0; index--) {
963 if (result[index] == '+') {
964 result[index] = JVM_SIGNATURE_DOT;
965 break;
966 }
967 }
968 return result;
969 }
970 return name()->as_C_string();
971 }
972
973 const char* Klass::external_kind() const {
974 if (is_interface()) return "interface";
975 if (is_abstract()) return "abstract class";
976 return "class";
977 }
978
979 // Unless overridden, jvmti_class_status has no flags set.
980 jint Klass::jvmti_class_status() const {
981 return 0;
982 }
983
984
985 // Printing
986
987 void Klass::print_on(outputStream* st) const {
988 ResourceMark rm;
989 // print title
990 st->print("%s", internal_name());
991 print_address_on(st);
992 st->cr();
993 }
994
995 #define BULLET " - "
996
997 // Caller needs ResourceMark
998 void Klass::oop_print_on(oop obj, outputStream* st) {
999 // print title
1000 st->print_cr("%s ", internal_name());
1001 obj->print_address_on(st);
1002
1003 if (WizardMode) {
1004 // print header
1005 obj->mark().print_on(st);
1006 st->cr();
1007 if (UseCompactObjectHeaders) {
1008 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
1009 st->cr();
1010 }
1011 }
1012
1013 // print class
1014 st->print(BULLET"klass: ");
1015 obj->klass()->print_value_on(st);
1016 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr();
1017 st->cr();
1018 }
1019
1020 void Klass::oop_print_value_on(oop obj, outputStream* st) {
1021 // print title
1022 ResourceMark rm; // Cannot print in debug mode without this
1023 st->print("%s", internal_name());
1024 obj->print_address_on(st);
1025 }
1026
1027 // Verification
1028
1029 void Klass::verify_on(outputStream* st) {
1030
1031 // This can be expensive, but it is worth checking that this klass is actually
1032 // in the CLD graph but not in production.
1033 #ifdef ASSERT
1034 if (UseCompressedClassPointers && needs_narrow_id()) {
1035 // Stricter checks for both correct alignment and placement
1036 CompressedKlassPointers::check_encodable(this);
1037 } else {
1038 assert(Metaspace::contains((address)this), "Should be");
1039 }
1040 #endif // ASSERT
1041
1042 guarantee(this->is_klass(),"should be klass");
1043
1044 if (super() != nullptr) {
1045 guarantee(super()->is_klass(), "should be klass");
1046 }
1047 if (secondary_super_cache() != nullptr) {
1048 Klass* ko = secondary_super_cache();
1049 guarantee(ko->is_klass(), "should be klass");
1050 }
1051 for ( uint i = 0; i < primary_super_limit(); i++ ) {
1052 Klass* ko = _primary_supers[i];
1053 if (ko != nullptr) {
1054 guarantee(ko->is_klass(), "should be klass");
1055 }
1056 }
1057
1058 if (java_mirror_no_keepalive() != nullptr) {
1059 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
1060 }
1061 }
1062
1063 void Klass::oop_verify_on(oop obj, outputStream* st) {
1064 guarantee(oopDesc::is_oop(obj), "should be oop");
1065 guarantee(obj->klass()->is_klass(), "klass field is not a klass");
1066 }
1067
1068 // Note: this function is called with an address that may or may not be a Klass.
1069 // The point is not to assert it is but to check if it could be.
1070 bool Klass::is_valid(Klass* k) {
1071 if (!is_aligned(k, sizeof(MetaWord))) return false;
1072 if ((size_t)k < os::min_page_size()) return false;
1073
1074 if (!os::is_readable_range(k, k + 1)) return false;
1075 if (!Metaspace::contains(k)) return false;
1076
1077 if (!Symbol::is_valid(k->name())) return false;
1078 return ClassLoaderDataGraph::is_valid(k->class_loader_data());
1079 }
1080
1081 Method* Klass::method_at_vtable(int index) {
1082 #ifndef PRODUCT
1083 assert(index >= 0, "valid vtable index");
1084 if (DebugVtables) {
1085 verify_vtable_index(index);
1086 }
1087 #endif
1088 return start_of_vtable()[index].method();
1089 }
1090
1091
1092 #ifndef PRODUCT
1093
1094 bool Klass::verify_vtable_index(int i) {
1095 int limit = vtable_length()/vtableEntry::size();
1096 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
1097 return true;
1098 }
1099
1100 #endif // PRODUCT
1101
1102 // Caller needs ResourceMark
1103 // joint_in_module_of_loader provides an optimization if 2 classes are in
1104 // the same module to succinctly print out relevant information about their
1105 // module name and class loader's name_and_id for error messages.
1106 // Format:
1107 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
1108 // are in module <module-name>[@<version>]
1109 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1110 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
1111 assert(module() == class2->module(), "classes do not have the same module");
1112 const char* class1_name = external_name();
1113 size_t len = strlen(class1_name) + 1;
1114
1115 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
1116 len += strlen(class2_description);
1117
1118 len += strlen(" and ");
1119
1120 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1121
1122 // Just return the FQN if error when allocating string
1123 if (joint_description == nullptr) {
1124 return class1_name;
1125 }
1126
1127 jio_snprintf(joint_description, len, "%s and %s",
1128 class1_name,
1129 class2_description);
1130
1131 return joint_description;
1132 }
1133
1134 // Caller needs ResourceMark
1135 // class_in_module_of_loader provides a standard way to include
1136 // relevant information about a class, such as its module name as
1137 // well as its class loader's name_and_id, in error messages and logging.
1138 // Format:
1139 // <fully-qualified-external-class-name> is in module <module-name>[@<version>]
1140 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1141 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
1142 // 1. fully qualified external name of class
1143 const char* klass_name = external_name();
1144 size_t len = strlen(klass_name) + 1;
1145
1146 // 2. module name + @version
1147 const char* module_name = "";
1148 const char* version = "";
1149 bool has_version = false;
1150 bool module_is_named = false;
1151 const char* module_name_phrase = "";
1152 const Klass* bottom_klass = is_objArray_klass() ?
1153 ObjArrayKlass::cast(this)->bottom_klass() : this;
1154 if (bottom_klass->is_instance_klass()) {
1155 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
1156 if (module->is_named()) {
1157 module_is_named = true;
1158 module_name_phrase = "module ";
1159 module_name = module->name()->as_C_string();
1160 len += strlen(module_name);
1161 // Use version if exists and is not a jdk module
1162 if (module->should_show_version()) {
1163 has_version = true;
1164 version = module->version()->as_C_string();
1165 // Include stlen(version) + 1 for the "@"
1166 len += strlen(version) + 1;
1167 }
1168 } else {
1169 module_name = UNNAMED_MODULE;
1170 len += UNNAMED_MODULE_LEN;
1171 }
1172 } else {
1173 // klass is an array of primitives, module is java.base
1174 module_is_named = true;
1175 module_name_phrase = "module ";
1176 module_name = JAVA_BASE_NAME;
1177 len += JAVA_BASE_NAME_LEN;
1178 }
1179
1180 // 3. class loader's name_and_id
1181 ClassLoaderData* cld = class_loader_data();
1182 assert(cld != nullptr, "class_loader_data should not be null");
1183 const char* loader_name_and_id = cld->loader_name_and_id();
1184 len += strlen(loader_name_and_id);
1185
1186 // 4. include parent loader information
1187 const char* parent_loader_phrase = "";
1188 const char* parent_loader_name_and_id = "";
1189 if (include_parent_loader &&
1190 !cld->is_builtin_class_loader_data()) {
1191 oop parent_loader = java_lang_ClassLoader::parent(class_loader());
1192 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
1193 // The parent loader's ClassLoaderData could be null if it is
1194 // a delegating class loader that has never defined a class.
1195 // In this case the loader's name must be obtained via the parent loader's oop.
1196 if (parent_cld == nullptr) {
1197 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
1198 if (cl_name_and_id != nullptr) {
1199 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
1200 }
1201 } else {
1202 parent_loader_name_and_id = parent_cld->loader_name_and_id();
1203 }
1204 parent_loader_phrase = ", parent loader ";
1205 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
1206 }
1207
1208 // Start to construct final full class description string
1209 len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
1210 len += strlen(module_name_phrase) + strlen(" of loader ");
1211
1212 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1213
1214 // Just return the FQN if error when allocating string
1215 if (class_description == nullptr) {
1216 return klass_name;
1217 }
1218
1219 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
1220 klass_name,
1221 (use_are) ? "are" : "is",
1222 module_name_phrase,
1223 module_name,
1224 (has_version) ? "@" : "",
1225 (has_version) ? version : "",
1226 loader_name_and_id,
1227 parent_loader_phrase,
1228 parent_loader_name_and_id);
1229
1230 return class_description;
1231 }
1232
1233 class LookupStats : StackObj {
1234 private:
1235 uint _no_of_samples;
1236 uint _worst;
1237 uint _worst_count;
1238 uint _average;
1239 uint _best;
1240 uint _best_count;
1241 public:
1242 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {}
1243
1244 ~LookupStats() {
1245 assert(_best <= _worst || _no_of_samples == 0, "sanity");
1246 }
1247
1248 void sample(uint value) {
1249 ++_no_of_samples;
1250 _average += value;
1251
1252 if (_worst < value) {
1253 _worst = value;
1254 _worst_count = 1;
1255 } else if (_worst == value) {
1256 ++_worst_count;
1257 }
1258
1259 if (_best > value) {
1260 _best = value;
1261 _best_count = 1;
1262 } else if (_best == value) {
1263 ++_best_count;
1264 }
1265 }
1266
1267 void print_on(outputStream* st) const {
1268 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples);
1269 if (_best_count < _no_of_samples) {
1270 st->print("; average: %4.1f; worst: %2d (%4.1f%%)",
1271 (1.0 * _average) / _no_of_samples,
1272 _worst, (100.0 * _worst_count) / _no_of_samples);
1273 }
1274 }
1275 };
1276
1277 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) {
1278 int num_of_supers = secondary_supers->length();
1279
1280 LookupStats s;
1281 for (int i = 0; i < num_of_supers; i++) {
1282 Klass* secondary_super = secondary_supers->at(i);
1283 int home_slot = Klass::compute_home_slot(secondary_super, bitmap);
1284 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK);
1285 s.sample(score);
1286 }
1287 st->print("positive_lookup: "); s.print_on(st);
1288 }
1289
1290 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) {
1291 assert(~bitmap != 0, "no zeroes");
1292 uintx start = rotate_right(bitmap, slot);
1293 return count_trailing_zeros(~start);
1294 }
1295
1296 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) {
1297 LookupStats s;
1298 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
1299 uint score = compute_distance_to_nearest_zero(slot, bitmap);
1300 s.sample(score);
1301 }
1302 st->print("negative_lookup: "); s.print_on(st);
1303 }
1304
1305 void Klass::print_secondary_supers_on(outputStream* st) const {
1306 if (secondary_supers() != nullptr) {
1307 st->print(" - "); st->print("%d elements;", _secondary_supers->length());
1308 st->print_cr(" bitmap: " UINTX_FORMAT_X_0 ";", _secondary_supers_bitmap);
1309 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY &&
1310 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) {
1311 st->print(" - "); print_positive_lookup_stats(secondary_supers(),
1312 _secondary_supers_bitmap, st); st->cr();
1313 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr();
1314 }
1315 } else {
1316 st->print("null");
1317 }
1318 }
1319
1320 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) {
1321 ResourceMark rm;
1322 super->print();
1323 sub->print();
1324 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d",
1325 msg, sub->external_name(), super->external_name(), linear_result, table_result);
1326 }