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/numberSeq.hpp"
59 #include "utilities/powerOfTwo.hpp"
60 #include "utilities/rotate_bits.hpp"
61 #include "utilities/stack.inline.hpp"
62
63 void Klass::set_java_mirror(Handle m) {
64 assert(!m.is_null(), "New mirror should never be null.");
65 assert(_java_mirror.is_empty(), "should only be used to initialize mirror");
66 _java_mirror = class_loader_data()->add_handle(m);
67 }
68
69 bool Klass::is_cloneable() const {
70 return _misc_flags.is_cloneable_fast() ||
71 is_subtype_of(vmClasses::Cloneable_klass());
72 }
73
74 void Klass::set_is_cloneable() {
75 if (name() == vmSymbols::java_lang_invoke_MemberName()) {
76 assert(is_final(), "no subclasses allowed");
77 // MemberName cloning should not be intrinsified and always happen in JVM_Clone.
78 } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) {
79 // Reference cloning should not be intrinsified and always happen in JVM_Clone.
80 } else {
81 _misc_flags.set_is_cloneable_fast(true);
82 }
83 }
84
85 uint8_t Klass::compute_hash_slot(Symbol* n) {
86 uint hash_code;
87 // Special cases for the two superclasses of all Array instances.
88 // Code elsewhere assumes, for all instances of ArrayKlass, that
89 // these two interfaces will be in this order.
90
91 // We ensure there are some empty slots in the hash table between
92 // these two very common interfaces because if they were adjacent
93 // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1
94 // would result in a probe length of 3.
95 if (n == vmSymbols::java_lang_Cloneable()) {
96 hash_code = 0;
97 } else if (n == vmSymbols::java_io_Serializable()) {
98 hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2;
99 } else {
100 auto s = (const jbyte*) n->bytes();
101 hash_code = java_lang_String::hash_code(s, n->utf8_length());
102 // We use String::hash_code here (rather than e.g.
103 // Symbol::identity_hash()) in order to have a hash code that
104 // does not change from run to run. We want that because the
105 // hash value for a secondary superclass appears in generated
106 // code as a constant.
107
108 // This constant is magic: see Knuth, "Fibonacci Hashing".
109 constexpr uint multiplier
110 = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 ))
111 constexpr uint hash_shift = sizeof(hash_code) * 8 - 6;
112 // The leading bits of the least significant half of the product.
113 hash_code = (hash_code * multiplier) >> hash_shift;
114
115 if (StressSecondarySupers) {
116 // Generate many hash collisions in order to stress-test the
117 // linear search fallback.
118 hash_code = hash_code % 3;
119 hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3);
120 }
121 }
122
123 return (hash_code & SECONDARY_SUPERS_TABLE_MASK);
124 }
125
126 void Klass::set_name(Symbol* n) {
127 _name = n;
128
129 if (_name != nullptr) {
130 _name->increment_refcount();
131 }
132
133 {
134 elapsedTimer selftime;
135 selftime.start();
136
137 _hash_slot = compute_hash_slot(n);
138 assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required");
139
140 selftime.stop();
141 if (UsePerfData) {
142 ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks());
143 }
144 }
145
146 if (CDSConfig::is_dumping_archive() && is_instance_klass()) {
147 SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this));
148 }
149 }
150
151 bool Klass::is_subclass_of(const Klass* k) const {
152 // Run up the super chain and check
153 if (this == k) return true;
154
155 Klass* t = const_cast<Klass*>(this)->super();
156
157 while (t != nullptr) {
158 if (t == k) return true;
159 t = t->super();
160 }
161 return false;
162 }
163
164 void Klass::release_C_heap_structures(bool release_constant_pool) {
165 if (_name != nullptr) _name->decrement_refcount();
166 }
167
168 bool Klass::linear_search_secondary_supers(const Klass* k) const {
169 // Scan the array-of-objects for a match
170 // FIXME: We could do something smarter here, maybe a vectorized
171 // comparison or a binary search, but is that worth any added
172 // complexity?
173 int cnt = secondary_supers()->length();
174 for (int i = 0; i < cnt; i++) {
175 if (secondary_supers()->at(i) == k) {
176 return true;
177 }
178 }
179 return false;
180 }
181
182 // Given a secondary superklass k, an initial array index, and an
183 // occupancy bitmap rotated such that Bit 1 is the next bit to test,
184 // search for k.
185 bool Klass::fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const {
186 // Once the occupancy bitmap is almost full, it's faster to use a
187 // linear search.
188 if (secondary_supers()->length() > SECONDARY_SUPERS_TABLE_SIZE - 2) {
189 return linear_search_secondary_supers(k);
190 }
191
192 // This is conventional linear probing, but instead of terminating
193 // when a null entry is found in the table, we maintain a bitmap
194 // in which a 0 indicates missing entries.
195
196 precond((int)population_count(rotated_bitmap) == secondary_supers()->length());
197
198 // The check for secondary_supers()->length() <= SECONDARY_SUPERS_TABLE_SIZE - 2
199 // at the start of this function guarantees there are 0s in the
200 // bitmap, so this loop eventually terminates.
201 while ((rotated_bitmap & 2) != 0) {
202 if (++index == secondary_supers()->length()) {
203 index = 0;
204 }
205 if (secondary_supers()->at(index) == k) {
206 return true;
207 }
208 rotated_bitmap = rotate_right(rotated_bitmap, 1);
209 }
210 return false;
211 }
212
213 // Return self, except for abstract classes with exactly 1
214 // implementor. Then return the 1 concrete implementation.
215 Klass *Klass::up_cast_abstract() {
216 Klass *r = this;
217 while( r->is_abstract() ) { // Receiver is abstract?
218 Klass *s = r->subklass(); // Check for exactly 1 subklass
219 if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up
220 return this; // Return 'this' as a no-progress flag
221 r = s; // Loop till find concrete class
222 }
223 return r; // Return the 1 concrete class
224 }
225
226 // Find LCA in class hierarchy
227 Klass *Klass::LCA( Klass *k2 ) {
228 Klass *k1 = this;
229 while( 1 ) {
230 if( k1->is_subtype_of(k2) ) return k2;
231 if( k2->is_subtype_of(k1) ) return k1;
232 k1 = k1->super();
233 k2 = k2->super();
234 }
235 }
236
237
238 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) {
239 ResourceMark rm(THREAD);
240 THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
241 : vmSymbols::java_lang_InstantiationException(), external_name());
242 }
243
244
245 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) {
246 ResourceMark rm(THREAD);
247 assert(s != nullptr, "Throw NPE!");
248 THROW_MSG(vmSymbols::java_lang_ArrayStoreException(),
249 err_msg("arraycopy: source type %s is not an array", s->klass()->external_name()));
250 }
251
252
253 void Klass::initialize(TRAPS) {
254 ShouldNotReachHere();
255 }
256
257 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
258 #ifdef ASSERT
259 tty->print_cr("Error: find_field called on a klass oop."
260 " Likely error: reflection method does not correctly"
261 " wrap return value in a mirror object.");
262 #endif
263 ShouldNotReachHere();
264 return nullptr;
265 }
266
267 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature,
268 OverpassLookupMode overpass_mode,
269 PrivateLookupMode private_mode) const {
270 #ifdef ASSERT
271 tty->print_cr("Error: uncached_lookup_method called on a klass oop."
272 " Likely error: reflection method does not correctly"
273 " wrap return value in a mirror object.");
274 #endif
275 ShouldNotReachHere();
276 return nullptr;
277 }
278
279 static markWord make_prototype(const Klass* kls) {
280 markWord prototype = markWord::prototype();
281 #ifdef _LP64
282 if (UseCompactObjectHeaders) {
283 // With compact object headers, the narrow Klass ID is part of the mark word.
284 // We therfore seed the mark word with the narrow Klass ID.
285 // Note that only those Klass that can be instantiated have a narrow Klass ID.
286 // For those who don't, we leave the klass bits empty and assert if someone
287 // tries to use those.
288 const narrowKlass nk = CompressedKlassPointers::is_encodable(kls) ?
289 CompressedKlassPointers::encode(const_cast<Klass*>(kls)) : 0;
290 prototype = prototype.set_narrow_klass(nk);
291 }
292 #endif
293 return prototype;
294 }
295
296 Klass::Klass() : _kind(UnknownKlassKind) {
297 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds");
298 }
299
300 // "Normal" instantiation is preceded by a MetaspaceObj allocation
301 // which zeros out memory - calloc equivalent.
302 // The constructor is also used from CppVtableCloner,
303 // which doesn't zero out the memory before calling the constructor.
304 Klass::Klass(KlassKind kind) : _kind(kind),
305 _prototype_header(make_prototype(this)),
306 _shared_class_path_index(-1) {
307 CDS_ONLY(_shared_class_flags = 0;)
308 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;)
309 _primary_supers[0] = this;
310 set_super_check_offset(in_bytes(primary_supers_offset()));
311 }
312
313 jint Klass::array_layout_helper(BasicType etype) {
314 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype");
315 // Note that T_ARRAY is not allowed here.
316 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
317 int esize = type2aelembytes(etype);
318 bool isobj = (etype == T_OBJECT);
319 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value;
320 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize));
321
322 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
323 assert(layout_helper_is_array(lh), "correct kind");
324 assert(layout_helper_is_objArray(lh) == isobj, "correct kind");
325 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind");
326 assert(layout_helper_header_size(lh) == hsize, "correct decode");
327 assert(layout_helper_element_type(lh) == etype, "correct decode");
328 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode");
329
330 return lh;
331 }
332
333 bool Klass::can_be_primary_super_slow() const {
334 if (super() == nullptr)
335 return true;
336 else if (super()->super_depth() >= primary_super_limit()-1)
337 return false;
338 else
339 return true;
340 }
341
342 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) {
343 #ifdef ASSERT
344 if (secondaries != nullptr) {
345 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries);
346 assert(bitmap == real_bitmap, "must be");
347 assert(secondaries->length() >= (int)population_count(bitmap), "must be");
348 }
349 #endif
350 _secondary_supers_bitmap = bitmap;
351 _secondary_supers = secondaries;
352
353 if (secondaries != nullptr) {
354 LogMessage(class, load) msg;
355 NonInterleavingLogStream log {LogLevel::Debug, msg};
356 if (log.is_enabled()) {
357 ResourceMark rm;
358 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name());
359 print_secondary_supers_on(&log);
360 }
361 }
362 }
363
364 // Hashed secondary superclasses
365 //
366 // We use a compressed 64-entry hash table with linear probing. We
367 // start by creating a hash table in the usual way, followed by a pass
368 // that removes all the null entries. To indicate which entries would
369 // have been null we use a bitmap that contains a 1 in each position
370 // where an entry is present, 0 otherwise. This bitmap also serves as
371 // a kind of Bloom filter, which in many cases allows us quickly to
372 // eliminate the possibility that something is a member of a set of
373 // secondaries.
374 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) {
375 const int length = secondaries->length();
376
377 if (length == 0) {
378 return SECONDARY_SUPERS_BITMAP_EMPTY;
379 }
380
381 if (length == 1) {
382 int hash_slot = secondaries->at(0)->hash_slot();
383 return uintx(1) << hash_slot;
384 }
385
386 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)
387
388 // Don't attempt to hash a table that's completely full, because in
389 // the case of an absent interface linear probing would not
390 // terminate.
391 if (length >= SECONDARY_SUPERS_TABLE_SIZE) {
392 return SECONDARY_SUPERS_BITMAP_FULL;
393 }
394
395 {
396 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time());
397
398 ResourceMark rm;
399 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY;
400 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE,
401 SECONDARY_SUPERS_TABLE_SIZE, nullptr);
402
403 for (int j = 0; j < length; j++) {
404 Klass* k = secondaries->at(j);
405 hash_insert(k, hashed_secondaries, bitmap);
406 }
407
408 // Pack the hashed secondaries array by copying it into the
409 // secondaries array, sans nulls, if modification is allowed.
410 // Otherwise, validate the order.
411 int i = 0;
412 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) {
413 bool has_element = ((bitmap >> slot) & 1) != 0;
414 assert(has_element == (hashed_secondaries->at(slot) != nullptr), "");
415 if (has_element) {
416 Klass* k = hashed_secondaries->at(slot);
417 if (rewrite) {
418 secondaries->at_put(i, k);
419 } else if (secondaries->at(i) != k) {
420 assert(false, "broken secondary supers hash table");
421 return SECONDARY_SUPERS_BITMAP_FULL;
422 }
423 i++;
424 }
425 }
426 assert(i == secondaries->length(), "mismatch");
427 postcond((int)population_count(bitmap) == secondaries->length());
428
429 return bitmap;
430 }
431 }
432
433 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) {
434 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
435
436 int dist = 0;
437 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) {
438 Klass* existing = secondaries->at(slot);
439 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch");
440 if (existing == nullptr) { // no conflict
441 secondaries->at_put(slot, klass);
442 bitmap |= uintx(1) << slot;
443 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, "");
444 return;
445 } else {
446 // Use Robin Hood hashing to minimize the worst case search.
447 // Also, every permutation of the insertion sequence produces
448 // the same final Robin Hood hash table, provided that a
449 // consistent tie breaker is used.
450 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK;
451 if (existing_dist < dist
452 // This tie breaker ensures that the hash order is maintained.
453 || ((existing_dist == dist)
454 && (uintptr_t(existing) < uintptr_t(klass)))) {
455 Klass* tmp = secondaries->at(slot);
456 secondaries->at_put(slot, klass);
457 klass = tmp;
458 dist = existing_dist;
459 }
460 ++dist;
461 }
462 }
463 }
464
465 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data,
466 GrowableArray<Klass*>* primaries,
467 GrowableArray<Klass*>* secondaries,
468 uintx& bitmap, TRAPS) {
469 int new_length = primaries->length() + secondaries->length();
470 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL);
471
472 // Combine the two arrays into a metadata object to pack the array.
473 // The primaries are added in the reverse order, then the secondaries.
474 int fill_p = primaries->length();
475 for (int j = 0; j < fill_p; j++) {
476 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order.
477 }
478 for( int j = 0; j < secondaries->length(); j++ ) {
479 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end.
480 }
481 #ifdef ASSERT
482 // We must not copy any null placeholders left over from bootstrap.
483 for (int j = 0; j < secondary_supers->length(); j++) {
484 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order");
485 }
486 #endif
487
488 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array
489 return secondary_supers;
490 }
491
492 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) {
493 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed
494 }
495
496 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) {
497 uint8_t hash = k->hash_slot();
498 if (hash > 0) {
499 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash));
500 }
501 return 0;
502 }
503
504
505 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) {
506 if (k == nullptr) {
507 set_super(nullptr);
508 _primary_supers[0] = this;
509 assert(super_depth() == 0, "Object must already be initialized properly");
510 } else if (k != super() || k == vmClasses::Object_klass()) {
511 assert(super() == nullptr || super() == vmClasses::Object_klass(),
512 "initialize this only once to a non-trivial value");
513 set_super(k);
514 Klass* sup = k;
515 int sup_depth = sup->super_depth();
516 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit());
517 if (!can_be_primary_super_slow())
518 my_depth = primary_super_limit();
519 for (juint i = 0; i < my_depth; i++) {
520 _primary_supers[i] = sup->_primary_supers[i];
521 }
522 Klass* *super_check_cell;
523 if (my_depth < primary_super_limit()) {
524 _primary_supers[my_depth] = this;
525 super_check_cell = &_primary_supers[my_depth];
526 } else {
527 // Overflow of the primary_supers array forces me to be secondary.
528 super_check_cell = &_secondary_super_cache;
529 }
530 set_super_check_offset(u4((address)super_check_cell - (address) this));
531
532 #ifdef ASSERT
533 {
534 juint j = super_depth();
535 assert(j == my_depth, "computed accessor gets right answer");
536 Klass* t = this;
537 while (!t->can_be_primary_super()) {
538 t = t->super();
539 j = t->super_depth();
540 }
541 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) {
542 assert(primary_super_of_depth(j1) == nullptr, "super list padding");
543 }
544 while (t != nullptr) {
545 assert(primary_super_of_depth(j) == t, "super list initialization");
546 t = t->super();
547 --j;
548 }
549 assert(j == (juint)-1, "correct depth count");
550 }
551 #endif
552 }
553
554 if (secondary_supers() == nullptr) {
555
556 // Now compute the list of secondary supertypes.
557 // Secondaries can occasionally be on the super chain,
558 // if the inline "_primary_supers" array overflows.
559 int extras = 0;
560 Klass* p;
561 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
562 ++extras;
563 }
564
565 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below
566
567 // Compute the "real" non-extra secondaries.
568 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces);
569 if (secondaries == nullptr) {
570 // secondary_supers set by compute_secondary_supers
571 return;
572 }
573
574 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras);
575
576 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) {
577 int i; // Scan for overflow primaries being duplicates of 2nd'arys
578
579 // This happens frequently for very deeply nested arrays: the
580 // primary superclass chain overflows into the secondary. The
581 // secondary list contains the element_klass's secondaries with
582 // an extra array dimension added. If the element_klass's
583 // secondary list already contains some primary overflows, they
584 // (with the extra level of array-ness) will collide with the
585 // normal primary superclass overflows.
586 for( i = 0; i < secondaries->length(); i++ ) {
587 if( secondaries->at(i) == p )
588 break;
589 }
590 if( i < secondaries->length() )
591 continue; // It's a dup, don't put it in
592 primaries->push(p);
593 }
594 // Combine the two arrays into a metadata object to pack the array.
595 uintx bitmap = 0;
596 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK);
597 set_secondary_supers(s2, bitmap);
598 }
599 }
600
601 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots,
602 Array<InstanceKlass*>* transitive_interfaces) {
603 assert(num_extra_slots == 0, "override for complex klasses");
604 assert(transitive_interfaces == nullptr, "sanity");
605 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap());
606 return nullptr;
607 }
608
609
610 // superklass links
611 InstanceKlass* Klass::superklass() const {
612 assert(super() == nullptr || super()->is_instance_klass(), "must be instance klass");
613 return _super == nullptr ? nullptr : InstanceKlass::cast(_super);
614 }
615
616 // subklass links. Used by the compiler (and vtable initialization)
617 // May be cleaned concurrently, so must use the Compile_lock.
618 // The log parameter is for clean_weak_klass_links to report unlinked classes.
619 Klass* Klass::subklass(bool log) const {
620 // Need load_acquire on the _subklass, because it races with inserts that
621 // publishes freshly initialized data.
622 for (Klass* chain = Atomic::load_acquire(&_subklass);
623 chain != nullptr;
624 // Do not need load_acquire on _next_sibling, because inserts never
625 // create _next_sibling edges to dead data.
626 chain = Atomic::load(&chain->_next_sibling))
627 {
628 if (chain->is_loader_alive()) {
629 return chain;
630 } else if (log) {
631 if (log_is_enabled(Trace, class, unload)) {
632 ResourceMark rm;
633 log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name());
634 }
635 }
636 }
637 return nullptr;
638 }
639
640 Klass* Klass::next_sibling(bool log) const {
641 // Do not need load_acquire on _next_sibling, because inserts never
642 // create _next_sibling edges to dead data.
643 for (Klass* chain = Atomic::load(&_next_sibling);
644 chain != nullptr;
645 chain = Atomic::load(&chain->_next_sibling)) {
646 // Only return alive klass, there may be stale klass
647 // in this chain if cleaned concurrently.
648 if (chain->is_loader_alive()) {
649 return chain;
650 } else if (log) {
651 if (log_is_enabled(Trace, class, unload)) {
652 ResourceMark rm;
653 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name());
654 }
655 }
656 }
657 return nullptr;
658 }
659
660 void Klass::set_subklass(Klass* s) {
661 assert(s != this, "sanity check");
662 Atomic::release_store(&_subklass, s);
663 }
664
665 void Klass::set_next_sibling(Klass* s) {
666 assert(s != this, "sanity check");
667 // Does not need release semantics. If used by cleanup, it will link to
668 // already safely published data, and if used by inserts, will be published
669 // safely using cmpxchg.
670 Atomic::store(&_next_sibling, s);
671 }
672
673 void Klass::append_to_sibling_list() {
674 if (Universe::is_fully_initialized()) {
675 assert_locked_or_safepoint(Compile_lock);
676 }
677 debug_only(verify();)
678 // add ourselves to superklass' subklass list
679 InstanceKlass* super = superklass();
680 if (super == nullptr) return; // special case: class Object
681 assert((!super->is_interface() // interfaces cannot be supers
682 && (super->superklass() == nullptr || !is_interface())),
683 "an interface can only be a subklass of Object");
684
685 // Make sure there is no stale subklass head
686 super->clean_subklass();
687
688 for (;;) {
689 Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass);
690 if (prev_first_subklass != nullptr) {
691 // set our sibling to be the superklass' previous first subklass
692 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses");
693 set_next_sibling(prev_first_subklass);
694 }
695 // Note that the prev_first_subklass is always alive, meaning no sibling_next links
696 // are ever created to not alive klasses. This is an important invariant of the lock-free
697 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list.
698 if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) {
699 return;
700 }
701 }
702 debug_only(verify();)
703 }
704
705 void Klass::clean_subklass() {
706 for (;;) {
707 // Need load_acquire, due to contending with concurrent inserts
708 Klass* subklass = Atomic::load_acquire(&_subklass);
709 if (subklass == nullptr || subklass->is_loader_alive()) {
710 return;
711 }
712 // Try to fix _subklass until it points at something not dead.
713 Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling());
714 }
715 }
716
717 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) {
718 if (!ClassUnloading || !unloading_occurred) {
719 return;
720 }
721
722 Klass* root = vmClasses::Object_klass();
723 Stack<Klass*, mtGC> stack;
724
725 stack.push(root);
726 while (!stack.is_empty()) {
727 Klass* current = stack.pop();
728
729 assert(current->is_loader_alive(), "just checking, this should be live");
730
731 // Find and set the first alive subklass
732 Klass* sub = current->subklass(true);
733 current->clean_subklass();
734 if (sub != nullptr) {
735 stack.push(sub);
736 }
737
738 // Find and set the first alive sibling
739 Klass* sibling = current->next_sibling(true);
740 current->set_next_sibling(sibling);
741 if (sibling != nullptr) {
742 stack.push(sibling);
743 }
744
745 // Clean the implementors list and method data.
746 if (clean_alive_klasses && current->is_instance_klass()) {
747 InstanceKlass* ik = InstanceKlass::cast(current);
748 ik->clean_weak_instanceklass_links();
749
750 // JVMTI RedefineClasses creates previous versions that are not in
751 // the class hierarchy, so process them here.
752 while ((ik = ik->previous_versions()) != nullptr) {
753 ik->clean_weak_instanceklass_links();
754 }
755 }
756 }
757 }
758
759 void Klass::metaspace_pointers_do(MetaspaceClosure* it) {
760 if (log_is_enabled(Trace, cds)) {
761 ResourceMark rm;
762 log_trace(cds)("Iter(Klass): %p (%s)", this, external_name());
763 }
764
765 it->push(&_name);
766 it->push(&_secondary_supers);
767 for (int i = 0; i < _primary_super_limit; i++) {
768 it->push(&_primary_supers[i]);
769 }
770 it->push(&_super);
771 if (!CDSConfig::is_dumping_archive()) {
772 // If dumping archive, these may point to excluded classes. There's no need
773 // to follow these pointers anyway, as they will be set to null in
774 // remove_unshareable_info().
775 it->push((Klass**)&_subklass);
776 it->push((Klass**)&_next_sibling);
777 it->push(&_next_link);
778 }
779
780 vtableEntry* vt = start_of_vtable();
781 for (int i=0; i<vtable_length(); i++) {
782 it->push(vt[i].method_addr());
783 }
784 }
785
786 #if INCLUDE_CDS
787 void Klass::remove_unshareable_info() {
788 assert(CDSConfig::is_dumping_archive(),
789 "only called during CDS dump time");
790 JFR_ONLY(REMOVE_ID(this);)
791 if (log_is_enabled(Trace, cds, unshareable)) {
792 ResourceMark rm;
793 log_trace(cds, unshareable)("remove: %s", external_name());
794 }
795
796 // _secondary_super_cache may be updated by an is_subtype_of() call
797 // while ArchiveBuilder is copying metaspace objects. Let's reset it to
798 // null and let it be repopulated at runtime.
799 set_secondary_super_cache(nullptr);
800
801 set_subklass(nullptr);
802 set_next_sibling(nullptr);
803 set_next_link(nullptr);
804
805 // Null out class_loader_data because we don't share that yet.
806 set_class_loader_data(nullptr);
807 set_is_shared();
808
809 // FIXME: validation in Klass::hash_secondary_supers() may fail for shared klasses.
810 // Even though the bitmaps always match, the canonical order of elements in the table
811 // is not guaranteed to stay the same (see tie breaker during Robin Hood hashing in Klass::hash_insert).
812 //assert(compute_secondary_supers_bitmap(secondary_supers()) == _secondary_supers_bitmap, "broken table");
813 }
814
815 void Klass::remove_java_mirror() {
816 assert(CDSConfig::is_dumping_archive(), "sanity");
817 if (log_is_enabled(Trace, cds, unshareable)) {
818 ResourceMark rm;
819 log_trace(cds, unshareable)("remove java_mirror: %s", external_name());
820 }
821 // Just null out the mirror. The class_loader_data() no longer exists.
822 clear_java_mirror_handle();
823 }
824
825 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
826 assert(is_klass(), "ensure C++ vtable is restored");
827 assert(is_shared(), "must be set");
828 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be");
829 JFR_ONLY(RESTORE_ID(this);)
830 if (log_is_enabled(Trace, cds, unshareable)) {
831 ResourceMark rm(THREAD);
832 oop class_loader = loader_data->class_loader();
833 log_trace(cds, unshareable)("restore: %s with class loader: %s", external_name(),
834 class_loader != nullptr ? class_loader->klass()->external_name() : "boot");
835 }
836
837 // If an exception happened during CDS restore, some of these fields may already be
838 // set. We leave the class on the CLD list, even if incomplete so that we don't
839 // modify the CLD list outside a safepoint.
840 if (class_loader_data() == nullptr) {
841 set_class_loader_data(loader_data);
842
843 // Add to class loader list first before creating the mirror
844 // (same order as class file parsing)
845 loader_data->add_class(this);
846 }
847
848 Handle loader(THREAD, loader_data->class_loader());
849 ModuleEntry* module_entry = nullptr;
850 Klass* k = this;
851 if (k->is_objArray_klass()) {
852 k = ObjArrayKlass::cast(k)->bottom_klass();
853 }
854 // Obtain klass' module.
855 if (k->is_instance_klass()) {
856 InstanceKlass* ik = (InstanceKlass*) k;
857 module_entry = ik->module();
858 } else {
859 module_entry = ModuleEntryTable::javabase_moduleEntry();
860 }
861 // Obtain java.lang.Module, if available
862 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module() : (oop)nullptr));
863
864 if (this->has_archived_mirror_index()) {
865 ResourceMark rm(THREAD);
866 log_debug(cds, mirror)("%s has raw archived mirror", external_name());
867 if (ArchiveHeapLoader::is_in_use()) {
868 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle,
869 protection_domain,
870 CHECK);
871 if (present) {
872 return;
873 }
874 }
875
876 // No archived mirror data
877 log_debug(cds, mirror)("No archived mirror data for %s", external_name());
878 clear_java_mirror_handle();
879 this->clear_archived_mirror_index();
880 }
881
882 // Only recreate it if not present. A previous attempt to restore may have
883 // gotten an OOM later but keep the mirror if it was created.
884 if (java_mirror() == nullptr) {
885 ResourceMark rm(THREAD);
886 log_trace(cds, mirror)("Recreate mirror for %s", external_name());
887 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK);
888 }
889 }
890 #endif // INCLUDE_CDS
891
892 #if INCLUDE_CDS_JAVA_HEAP
893 oop Klass::archived_java_mirror() {
894 assert(has_archived_mirror_index(), "must have archived mirror");
895 return HeapShared::get_root(_archived_mirror_index);
896 }
897
898 void Klass::clear_archived_mirror_index() {
899 if (_archived_mirror_index >= 0) {
900 HeapShared::clear_root(_archived_mirror_index);
901 }
902 _archived_mirror_index = -1;
903 }
904
905 // No GC barrier
906 void Klass::set_archived_java_mirror(int mirror_index) {
907 assert(CDSConfig::is_dumping_heap(), "sanity");
908 _archived_mirror_index = mirror_index;
909 }
910 #endif // INCLUDE_CDS_JAVA_HEAP
911
912 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) {
913 if (length > max_length) {
914 if (!THREAD->is_in_internal_oome_mark()) {
915 report_java_out_of_memory("Requested array size exceeds VM limit");
916 JvmtiExport::post_array_size_exhausted();
917 THROW_OOP(Universe::out_of_memory_error_array_size());
918 } else {
919 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace());
920 }
921 } else if (length < 0) {
922 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length));
923 }
924 }
925
926 // Replace the last '+' char with '/'.
927 static char* convert_hidden_name_to_java(Symbol* name) {
928 size_t name_len = name->utf8_length();
929 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
930 name->as_klass_external_name(result, (int)name_len + 1);
931 for (int index = (int)name_len; index > 0; index--) {
932 if (result[index] == '+') {
933 result[index] = JVM_SIGNATURE_SLASH;
934 break;
935 }
936 }
937 return result;
938 }
939
940 // In product mode, this function doesn't have virtual function calls so
941 // there might be some performance advantage to handling InstanceKlass here.
942 const char* Klass::external_name() const {
943 if (is_instance_klass()) {
944 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this);
945 if (ik->is_hidden()) {
946 char* result = convert_hidden_name_to_java(name());
947 return result;
948 }
949 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
950 char* result = convert_hidden_name_to_java(name());
951 return result;
952 }
953 if (name() == nullptr) return "<unknown>";
954 return name()->as_klass_external_name();
955 }
956
957 const char* Klass::signature_name() const {
958 if (name() == nullptr) return "<unknown>";
959 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) {
960 size_t name_len = name()->utf8_length();
961 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1);
962 name()->as_C_string(result, (int)name_len + 1);
963 for (int index = (int)name_len; index > 0; index--) {
964 if (result[index] == '+') {
965 result[index] = JVM_SIGNATURE_DOT;
966 break;
967 }
968 }
969 return result;
970 }
971 return name()->as_C_string();
972 }
973
974 const char* Klass::external_kind() const {
975 if (is_interface()) return "interface";
976 if (is_abstract()) return "abstract class";
977 return "class";
978 }
979
980 // Unless overridden, jvmti_class_status has no flags set.
981 jint Klass::jvmti_class_status() const {
982 return 0;
983 }
984
985
986 // Printing
987
988 void Klass::print_on(outputStream* st) const {
989 ResourceMark rm;
990 // print title
991 st->print("%s", internal_name());
992 print_address_on(st);
993 st->cr();
994 }
995
996 #define BULLET " - "
997
998 // Caller needs ResourceMark
999 void Klass::oop_print_on(oop obj, outputStream* st) {
1000 // print title
1001 st->print_cr("%s ", internal_name());
1002 obj->print_address_on(st);
1003
1004 if (WizardMode) {
1005 // print header
1006 obj->mark().print_on(st);
1007 st->cr();
1008 if (UseCompactObjectHeaders) {
1009 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value());
1010 st->cr();
1011 }
1012 }
1013
1014 // print class
1015 st->print(BULLET"klass: ");
1016 obj->klass()->print_value_on(st);
1017 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr();
1018 st->cr();
1019 }
1020
1021 void Klass::oop_print_value_on(oop obj, outputStream* st) {
1022 // print title
1023 ResourceMark rm; // Cannot print in debug mode without this
1024 st->print("%s", internal_name());
1025 obj->print_address_on(st);
1026 }
1027
1028 // Verification
1029
1030 void Klass::verify_on(outputStream* st) {
1031
1032 // This can be expensive, but it is worth checking that this klass is actually
1033 // in the CLD graph but not in production.
1034 #ifdef ASSERT
1035 if (UseCompressedClassPointers && needs_narrow_id()) {
1036 // Stricter checks for both correct alignment and placement
1037 CompressedKlassPointers::check_encodable(this);
1038 } else {
1039 assert(Metaspace::contains((address)this), "Should be");
1040 }
1041 #endif // ASSERT
1042
1043 guarantee(this->is_klass(),"should be klass");
1044
1045 if (super() != nullptr) {
1046 guarantee(super()->is_klass(), "should be klass");
1047 }
1048 if (secondary_super_cache() != nullptr) {
1049 Klass* ko = secondary_super_cache();
1050 guarantee(ko->is_klass(), "should be klass");
1051 }
1052 for ( uint i = 0; i < primary_super_limit(); i++ ) {
1053 Klass* ko = _primary_supers[i];
1054 if (ko != nullptr) {
1055 guarantee(ko->is_klass(), "should be klass");
1056 }
1057 }
1058
1059 if (java_mirror_no_keepalive() != nullptr) {
1060 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance");
1061 }
1062 }
1063
1064 void Klass::oop_verify_on(oop obj, outputStream* st) {
1065 guarantee(oopDesc::is_oop(obj), "should be oop");
1066 guarantee(obj->klass()->is_klass(), "klass field is not a klass");
1067 }
1068
1069 // Note: this function is called with an address that may or may not be a Klass.
1070 // The point is not to assert it is but to check if it could be.
1071 bool Klass::is_valid(Klass* k) {
1072 if (!is_aligned(k, sizeof(MetaWord))) return false;
1073 if ((size_t)k < os::min_page_size()) return false;
1074
1075 if (!os::is_readable_range(k, k + 1)) return false;
1076 if (!Metaspace::contains(k)) return false;
1077
1078 if (!Symbol::is_valid(k->name())) return false;
1079 return ClassLoaderDataGraph::is_valid(k->class_loader_data());
1080 }
1081
1082 Method* Klass::method_at_vtable(int index) {
1083 #ifndef PRODUCT
1084 assert(index >= 0, "valid vtable index");
1085 if (DebugVtables) {
1086 verify_vtable_index(index);
1087 }
1088 #endif
1089 return start_of_vtable()[index].method();
1090 }
1091
1092
1093 #ifndef PRODUCT
1094
1095 bool Klass::verify_vtable_index(int i) {
1096 int limit = vtable_length()/vtableEntry::size();
1097 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit);
1098 return true;
1099 }
1100
1101 #endif // PRODUCT
1102
1103 // Caller needs ResourceMark
1104 // joint_in_module_of_loader provides an optimization if 2 classes are in
1105 // the same module to succinctly print out relevant information about their
1106 // module name and class loader's name_and_id for error messages.
1107 // Format:
1108 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2>
1109 // are in module <module-name>[@<version>]
1110 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1111 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const {
1112 assert(module() == class2->module(), "classes do not have the same module");
1113 const char* class1_name = external_name();
1114 size_t len = strlen(class1_name) + 1;
1115
1116 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader);
1117 len += strlen(class2_description);
1118
1119 len += strlen(" and ");
1120
1121 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1122
1123 // Just return the FQN if error when allocating string
1124 if (joint_description == nullptr) {
1125 return class1_name;
1126 }
1127
1128 jio_snprintf(joint_description, len, "%s and %s",
1129 class1_name,
1130 class2_description);
1131
1132 return joint_description;
1133 }
1134
1135 // Caller needs ResourceMark
1136 // class_in_module_of_loader provides a standard way to include
1137 // relevant information about a class, such as its module name as
1138 // well as its class loader's name_and_id, in error messages and logging.
1139 // Format:
1140 // <fully-qualified-external-class-name> is in module <module-name>[@<version>]
1141 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>]
1142 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const {
1143 // 1. fully qualified external name of class
1144 const char* klass_name = external_name();
1145 size_t len = strlen(klass_name) + 1;
1146
1147 // 2. module name + @version
1148 const char* module_name = "";
1149 const char* version = "";
1150 bool has_version = false;
1151 bool module_is_named = false;
1152 const char* module_name_phrase = "";
1153 const Klass* bottom_klass = is_objArray_klass() ?
1154 ObjArrayKlass::cast(this)->bottom_klass() : this;
1155 if (bottom_klass->is_instance_klass()) {
1156 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module();
1157 if (module->is_named()) {
1158 module_is_named = true;
1159 module_name_phrase = "module ";
1160 module_name = module->name()->as_C_string();
1161 len += strlen(module_name);
1162 // Use version if exists and is not a jdk module
1163 if (module->should_show_version()) {
1164 has_version = true;
1165 version = module->version()->as_C_string();
1166 // Include stlen(version) + 1 for the "@"
1167 len += strlen(version) + 1;
1168 }
1169 } else {
1170 module_name = UNNAMED_MODULE;
1171 len += UNNAMED_MODULE_LEN;
1172 }
1173 } else {
1174 // klass is an array of primitives, module is java.base
1175 module_is_named = true;
1176 module_name_phrase = "module ";
1177 module_name = JAVA_BASE_NAME;
1178 len += JAVA_BASE_NAME_LEN;
1179 }
1180
1181 // 3. class loader's name_and_id
1182 ClassLoaderData* cld = class_loader_data();
1183 assert(cld != nullptr, "class_loader_data should not be null");
1184 const char* loader_name_and_id = cld->loader_name_and_id();
1185 len += strlen(loader_name_and_id);
1186
1187 // 4. include parent loader information
1188 const char* parent_loader_phrase = "";
1189 const char* parent_loader_name_and_id = "";
1190 if (include_parent_loader &&
1191 !cld->is_builtin_class_loader_data()) {
1192 oop parent_loader = java_lang_ClassLoader::parent(class_loader());
1193 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader);
1194 // The parent loader's ClassLoaderData could be null if it is
1195 // a delegating class loader that has never defined a class.
1196 // In this case the loader's name must be obtained via the parent loader's oop.
1197 if (parent_cld == nullptr) {
1198 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader);
1199 if (cl_name_and_id != nullptr) {
1200 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id);
1201 }
1202 } else {
1203 parent_loader_name_and_id = parent_cld->loader_name_and_id();
1204 }
1205 parent_loader_phrase = ", parent loader ";
1206 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id);
1207 }
1208
1209 // Start to construct final full class description string
1210 len += ((use_are) ? strlen(" are in ") : strlen(" is in "));
1211 len += strlen(module_name_phrase) + strlen(" of loader ");
1212
1213 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len);
1214
1215 // Just return the FQN if error when allocating string
1216 if (class_description == nullptr) {
1217 return klass_name;
1218 }
1219
1220 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s",
1221 klass_name,
1222 (use_are) ? "are" : "is",
1223 module_name_phrase,
1224 module_name,
1225 (has_version) ? "@" : "",
1226 (has_version) ? version : "",
1227 loader_name_and_id,
1228 parent_loader_phrase,
1229 parent_loader_name_and_id);
1230
1231 return class_description;
1232 }
1233
1234 class LookupStats : StackObj {
1235 private:
1236 uint _no_of_samples;
1237 uint _worst;
1238 uint _worst_count;
1239 uint _average;
1240 uint _best;
1241 uint _best_count;
1242 public:
1243 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {}
1244
1245 ~LookupStats() {
1246 assert(_best <= _worst || _no_of_samples == 0, "sanity");
1247 }
1248
1249 void sample(uint value) {
1250 ++_no_of_samples;
1251 _average += value;
1252
1253 if (_worst < value) {
1254 _worst = value;
1255 _worst_count = 1;
1256 } else if (_worst == value) {
1257 ++_worst_count;
1258 }
1259
1260 if (_best > value) {
1261 _best = value;
1262 _best_count = 1;
1263 } else if (_best == value) {
1264 ++_best_count;
1265 }
1266 }
1267
1268 void print_on(outputStream* st) const {
1269 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples);
1270 if (_best_count < _no_of_samples) {
1271 st->print("; average: %4.1f; worst: %2d (%4.1f%%)",
1272 (1.0 * _average) / _no_of_samples,
1273 _worst, (100.0 * _worst_count) / _no_of_samples);
1274 }
1275 }
1276 };
1277
1278 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) {
1279 int num_of_supers = secondary_supers->length();
1280
1281 LookupStats s;
1282 for (int i = 0; i < num_of_supers; i++) {
1283 Klass* secondary_super = secondary_supers->at(i);
1284 int home_slot = Klass::compute_home_slot(secondary_super, bitmap);
1285 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK);
1286 s.sample(score);
1287 }
1288 st->print("positive_lookup: "); s.print_on(st);
1289 }
1290
1291 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) {
1292 assert(~bitmap != 0, "no zeroes");
1293 uintx start = rotate_right(bitmap, slot);
1294 return count_trailing_zeros(~start);
1295 }
1296
1297 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) {
1298 LookupStats s;
1299 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) {
1300 uint score = compute_distance_to_nearest_zero(slot, bitmap);
1301 s.sample(score);
1302 }
1303 st->print("negative_lookup: "); s.print_on(st);
1304 }
1305
1306 void Klass::print_secondary_supers_on(outputStream* st) const {
1307 if (secondary_supers() != nullptr) {
1308 st->print(" - "); st->print("%d elements;", _secondary_supers->length());
1309 st->print_cr(" bitmap: " UINTX_FORMAT_X_0 ";", _secondary_supers_bitmap);
1310 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY &&
1311 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) {
1312 st->print(" - "); print_positive_lookup_stats(secondary_supers(),
1313 _secondary_supers_bitmap, st); st->cr();
1314 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr();
1315 }
1316 } else {
1317 st->print("null");
1318 }
1319 }
1320
1321 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) {
1322 ResourceMark rm;
1323 super->print();
1324 sub->print();
1325 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d",
1326 msg, sub->external_name(), super->external_name(), linear_result, table_result);
1327 }
1328
1329 static int expanded = 0;
1330 static int not_expanded = 0;
1331 static NumberSeq seq = NumberSeq();
1332
1333 bool Klass::expand_for_hash(oop obj) const {
1334 assert(UseCompactObjectHeaders, "only with compact i-hash");
1335 assert((size_t)hash_offset_in_bytes(obj) <= (obj->base_size_given_klass(obj->mark(), this) * HeapWordSize), "hash offset must be eq or lt base size: hash offset: %d, base size: " SIZE_FORMAT, hash_offset_in_bytes(obj), obj->base_size_given_klass(obj->mark(), this) * HeapWordSize);
1336 return obj->base_size_given_klass(obj->mark(), this) * HeapWordSize - hash_offset_in_bytes(obj) < (int)sizeof(uint32_t);
1337 }