1 /* 2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "cds/cdsConfig.hpp" 26 #include "cds/heapShared.inline.hpp" 27 #include "classfile/classLoader.hpp" 28 #include "classfile/classLoaderData.inline.hpp" 29 #include "classfile/classLoaderDataGraph.inline.hpp" 30 #include "classfile/javaClasses.inline.hpp" 31 #include "classfile/moduleEntry.hpp" 32 #include "classfile/systemDictionary.hpp" 33 #include "classfile/systemDictionaryShared.hpp" 34 #include "classfile/vmClasses.hpp" 35 #include "classfile/vmSymbols.hpp" 36 #include "gc/shared/collectedHeap.inline.hpp" 37 #include "jvm_io.h" 38 #include "logging/log.hpp" 39 #include "memory/metadataFactory.hpp" 40 #include "memory/metaspaceClosure.hpp" 41 #include "memory/oopFactory.hpp" 42 #include "memory/resourceArea.hpp" 43 #include "memory/universe.hpp" 44 #include "oops/compressedKlass.inline.hpp" 45 #include "oops/compressedOops.inline.hpp" 46 #include "oops/instanceKlass.hpp" 47 #include "oops/klass.inline.hpp" 48 #include "oops/objArrayKlass.hpp" 49 #include "oops/oop.inline.hpp" 50 #include "oops/oopHandle.inline.hpp" 51 #include "prims/jvmtiExport.hpp" 52 #include "runtime/atomicAccess.hpp" 53 #include "runtime/handles.inline.hpp" 54 #include "runtime/perfData.hpp" 55 #include "utilities/macros.hpp" 56 #include "utilities/powerOfTwo.hpp" 57 #include "utilities/rotate_bits.hpp" 58 #include "utilities/stack.inline.hpp" 59 60 #if INCLUDE_JFR 61 #include "jfr/jfr.hpp" 62 #endif 63 64 void Klass::set_java_mirror(Handle m) { 65 assert(!m.is_null(), "New mirror should never be null."); 66 assert(_java_mirror.is_empty(), "should only be used to initialize mirror"); 67 _java_mirror = class_loader_data()->add_handle(m); 68 } 69 70 bool Klass::is_cloneable() const { 71 return _misc_flags.is_cloneable_fast() || 72 is_subtype_of(vmClasses::Cloneable_klass()); 73 } 74 75 uint8_t Klass::compute_hash_slot(Symbol* n) { 76 uint hash_code; 77 // Special cases for the two superclasses of all Array instances. 78 // Code elsewhere assumes, for all instances of ArrayKlass, that 79 // these two interfaces will be in this order. 80 81 // We ensure there are some empty slots in the hash table between 82 // these two very common interfaces because if they were adjacent 83 // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1 84 // would result in a probe length of 3. 85 if (n == vmSymbols::java_lang_Cloneable()) { 86 hash_code = 0; 87 } else if (n == vmSymbols::java_io_Serializable()) { 88 hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2; 89 } else { 90 auto s = (const jbyte*) n->bytes(); 91 hash_code = java_lang_String::hash_code(s, n->utf8_length()); 92 // We use String::hash_code here (rather than e.g. 93 // Symbol::identity_hash()) in order to have a hash code that 94 // does not change from run to run. We want that because the 95 // hash value for a secondary superclass appears in generated 96 // code as a constant. 97 98 // This constant is magic: see Knuth, "Fibonacci Hashing". 99 constexpr uint multiplier 100 = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 )) 101 constexpr uint hash_shift = sizeof(hash_code) * 8 - 6; 102 // The leading bits of the least significant half of the product. 103 hash_code = (hash_code * multiplier) >> hash_shift; 104 105 if (StressSecondarySupers) { 106 // Generate many hash collisions in order to stress-test the 107 // linear search fallback. 108 hash_code = hash_code % 3; 109 hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3); 110 } 111 } 112 113 return (hash_code & SECONDARY_SUPERS_TABLE_MASK); 114 } 115 116 void Klass::set_name(Symbol* n) { 117 _name = n; 118 119 if (_name != nullptr) { 120 _name->increment_refcount(); 121 } 122 123 { 124 elapsedTimer selftime; 125 selftime.start(); 126 127 _hash_slot = compute_hash_slot(n); 128 assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required"); 129 130 selftime.stop(); 131 if (UsePerfData) { 132 ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks()); 133 } 134 } 135 136 if (CDSConfig::is_dumping_archive() && is_instance_klass()) { 137 SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this)); 138 } 139 } 140 141 bool Klass::is_subclass_of(const Klass* k) const { 142 // Run up the super chain and check 143 if (this == k) return true; 144 145 Klass* t = const_cast<Klass*>(this)->super(); 146 147 while (t != nullptr) { 148 if (t == k) return true; 149 t = t->super(); 150 } 151 return false; 152 } 153 154 void Klass::release_C_heap_structures(bool release_constant_pool) { 155 if (_name != nullptr) _name->decrement_refcount(); 156 } 157 158 bool Klass::linear_search_secondary_supers(const Klass* k) const { 159 // Scan the array-of-objects for a match 160 // FIXME: We could do something smarter here, maybe a vectorized 161 // comparison or a binary search, but is that worth any added 162 // complexity? 163 int cnt = secondary_supers()->length(); 164 for (int i = 0; i < cnt; i++) { 165 if (secondary_supers()->at(i) == k) { 166 return true; 167 } 168 } 169 return false; 170 } 171 172 // Given a secondary superklass k, an initial array index, and an 173 // occupancy bitmap rotated such that Bit 1 is the next bit to test, 174 // search for k. 175 bool Klass::fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const { 176 // Once the occupancy bitmap is almost full, it's faster to use a 177 // linear search. 178 if (secondary_supers()->length() > SECONDARY_SUPERS_TABLE_SIZE - 2) { 179 return linear_search_secondary_supers(k); 180 } 181 182 // This is conventional linear probing, but instead of terminating 183 // when a null entry is found in the table, we maintain a bitmap 184 // in which a 0 indicates missing entries. 185 186 precond((int)population_count(rotated_bitmap) == secondary_supers()->length()); 187 188 // The check for secondary_supers()->length() <= SECONDARY_SUPERS_TABLE_SIZE - 2 189 // at the start of this function guarantees there are 0s in the 190 // bitmap, so this loop eventually terminates. 191 while ((rotated_bitmap & 2) != 0) { 192 if (++index == secondary_supers()->length()) { 193 index = 0; 194 } 195 if (secondary_supers()->at(index) == k) { 196 return true; 197 } 198 rotated_bitmap = rotate_right(rotated_bitmap, 1); 199 } 200 return false; 201 } 202 203 // Return self, except for abstract classes with exactly 1 204 // implementor. Then return the 1 concrete implementation. 205 Klass *Klass::up_cast_abstract() { 206 Klass *r = this; 207 while( r->is_abstract() ) { // Receiver is abstract? 208 Klass *s = r->subklass(); // Check for exactly 1 subklass 209 if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up 210 return this; // Return 'this' as a no-progress flag 211 r = s; // Loop till find concrete class 212 } 213 return r; // Return the 1 concrete class 214 } 215 216 // Find LCA in class hierarchy 217 Klass *Klass::LCA( Klass *k2 ) { 218 Klass *k1 = this; 219 while( 1 ) { 220 if( k1->is_subtype_of(k2) ) return k2; 221 if( k2->is_subtype_of(k1) ) return k1; 222 k1 = k1->super(); 223 k2 = k2->super(); 224 } 225 } 226 227 228 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) { 229 ResourceMark rm(THREAD); 230 THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError() 231 : vmSymbols::java_lang_InstantiationException(), external_name()); 232 } 233 234 235 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) { 236 ResourceMark rm(THREAD); 237 assert(s != nullptr, "Throw NPE!"); 238 THROW_MSG(vmSymbols::java_lang_ArrayStoreException(), 239 err_msg("arraycopy: source type %s is not an array", s->klass()->external_name())); 240 } 241 242 243 void Klass::initialize(TRAPS) { 244 ShouldNotReachHere(); 245 } 246 247 void Klass::initialize_preemptable(TRAPS) { 248 ShouldNotReachHere(); 249 } 250 251 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const { 252 #ifdef ASSERT 253 tty->print_cr("Error: find_field called on a klass oop." 254 " Likely error: reflection method does not correctly" 255 " wrap return value in a mirror object."); 256 #endif 257 ShouldNotReachHere(); 258 return nullptr; 259 } 260 261 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature, 262 OverpassLookupMode overpass_mode, 263 PrivateLookupMode private_mode) const { 264 #ifdef ASSERT 265 tty->print_cr("Error: uncached_lookup_method called on a klass oop." 266 " Likely error: reflection method does not correctly" 267 " wrap return value in a mirror object."); 268 #endif 269 ShouldNotReachHere(); 270 return nullptr; 271 } 272 273 static markWord make_prototype(const Klass* kls) { 274 markWord prototype = markWord::prototype(); 275 #ifdef _LP64 276 if (UseCompactObjectHeaders) { 277 // With compact object headers, the narrow Klass ID is part of the mark word. 278 // We therefore seed the mark word with the narrow Klass ID. 279 precond(CompressedKlassPointers::is_encodable(kls)); 280 const narrowKlass nk = CompressedKlassPointers::encode(const_cast<Klass*>(kls)); 281 prototype = prototype.set_narrow_klass(nk); 282 } 283 #endif 284 return prototype; 285 } 286 287 void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() { 288 return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD); 289 } 290 291 Klass::Klass() : _kind(UnknownKlassKind) { 292 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds"); 293 } 294 295 // "Normal" instantiation is preceded by a MetaspaceObj allocation 296 // which zeros out memory - calloc equivalent. 297 // The constructor is also used from CppVtableCloner, 298 // which doesn't zero out the memory before calling the constructor. 299 Klass::Klass(KlassKind kind) : _kind(kind), 300 _prototype_header(make_prototype(this)), 301 _shared_class_path_index(-1) { 302 CDS_ONLY(_aot_class_flags = 0;) 303 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;) 304 _primary_supers[0] = this; 305 set_super_check_offset(in_bytes(primary_supers_offset())); 306 } 307 308 jint Klass::array_layout_helper(BasicType etype) { 309 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype"); 310 // Note that T_ARRAY is not allowed here. 311 int hsize = arrayOopDesc::base_offset_in_bytes(etype); 312 int esize = type2aelembytes(etype); 313 bool isobj = (etype == T_OBJECT); 314 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value; 315 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize)); 316 317 assert(lh < (int)_lh_neutral_value, "must look like an array layout"); 318 assert(layout_helper_is_array(lh), "correct kind"); 319 assert(layout_helper_is_objArray(lh) == isobj, "correct kind"); 320 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind"); 321 assert(layout_helper_header_size(lh) == hsize, "correct decode"); 322 assert(layout_helper_element_type(lh) == etype, "correct decode"); 323 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode"); 324 325 return lh; 326 } 327 328 int Klass::modifier_flags() const { 329 int mods = java_lang_Class::modifiers(java_mirror()); 330 assert(mods == compute_modifier_flags(), "should be same"); 331 return mods; 332 } 333 334 bool Klass::can_be_primary_super_slow() const { 335 if (super() == nullptr) 336 return true; 337 else if (super()->super_depth() >= primary_super_limit()-1) 338 return false; 339 else 340 return true; 341 } 342 343 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) { 344 #ifdef ASSERT 345 if (secondaries != nullptr) { 346 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries); 347 assert(bitmap == real_bitmap, "must be"); 348 assert(secondaries->length() >= (int)population_count(bitmap), "must be"); 349 } 350 #endif 351 _secondary_supers_bitmap = bitmap; 352 _secondary_supers = secondaries; 353 354 if (secondaries != nullptr) { 355 LogMessage(class, load) msg; 356 NonInterleavingLogStream log {LogLevel::Debug, msg}; 357 if (log.is_enabled()) { 358 ResourceMark rm; 359 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name()); 360 print_secondary_supers_on(&log); 361 } 362 } 363 } 364 365 // Hashed secondary superclasses 366 // 367 // We use a compressed 64-entry hash table with linear probing. We 368 // start by creating a hash table in the usual way, followed by a pass 369 // that removes all the null entries. To indicate which entries would 370 // have been null we use a bitmap that contains a 1 in each position 371 // where an entry is present, 0 otherwise. This bitmap also serves as 372 // a kind of Bloom filter, which in many cases allows us quickly to 373 // eliminate the possibility that something is a member of a set of 374 // secondaries. 375 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) { 376 const int length = secondaries->length(); 377 378 if (length == 0) { 379 return SECONDARY_SUPERS_BITMAP_EMPTY; 380 } 381 382 if (length == 1) { 383 int hash_slot = secondaries->at(0)->hash_slot(); 384 return uintx(1) << hash_slot; 385 } 386 387 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap) 388 389 // Don't attempt to hash a table that's completely full, because in 390 // the case of an absent interface linear probing would not 391 // terminate. 392 if (length >= SECONDARY_SUPERS_TABLE_SIZE) { 393 return SECONDARY_SUPERS_BITMAP_FULL; 394 } 395 396 { 397 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time()); 398 399 ResourceMark rm; 400 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY; 401 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE, 402 SECONDARY_SUPERS_TABLE_SIZE, nullptr); 403 404 for (int j = 0; j < length; j++) { 405 Klass* k = secondaries->at(j); 406 hash_insert(k, hashed_secondaries, bitmap); 407 } 408 409 // Pack the hashed secondaries array by copying it into the 410 // secondaries array, sans nulls, if modification is allowed. 411 // Otherwise, validate the order. 412 int i = 0; 413 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) { 414 bool has_element = ((bitmap >> slot) & 1) != 0; 415 assert(has_element == (hashed_secondaries->at(slot) != nullptr), ""); 416 if (has_element) { 417 Klass* k = hashed_secondaries->at(slot); 418 if (rewrite) { 419 secondaries->at_put(i, k); 420 } else if (secondaries->at(i) != k) { 421 assert(false, "broken secondary supers hash table"); 422 return SECONDARY_SUPERS_BITMAP_FULL; 423 } 424 i++; 425 } 426 } 427 assert(i == secondaries->length(), "mismatch"); 428 postcond((int)population_count(bitmap) == secondaries->length()); 429 430 return bitmap; 431 } 432 } 433 434 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) { 435 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, ""); 436 437 int dist = 0; 438 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) { 439 Klass* existing = secondaries->at(slot); 440 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch"); 441 if (existing == nullptr) { // no conflict 442 secondaries->at_put(slot, klass); 443 bitmap |= uintx(1) << slot; 444 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, ""); 445 return; 446 } else { 447 // Use Robin Hood hashing to minimize the worst case search. 448 // Also, every permutation of the insertion sequence produces 449 // the same final Robin Hood hash table, provided that a 450 // consistent tie breaker is used. 451 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK; 452 if (existing_dist < dist 453 // This tie breaker ensures that the hash order is maintained. 454 || ((existing_dist == dist) 455 && (uintptr_t(existing) < uintptr_t(klass)))) { 456 Klass* tmp = secondaries->at(slot); 457 secondaries->at_put(slot, klass); 458 klass = tmp; 459 dist = existing_dist; 460 } 461 ++dist; 462 } 463 } 464 } 465 466 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data, 467 GrowableArray<Klass*>* primaries, 468 GrowableArray<Klass*>* secondaries, 469 uintx& bitmap, TRAPS) { 470 int new_length = primaries->length() + secondaries->length(); 471 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL); 472 473 // Combine the two arrays into a metadata object to pack the array. 474 // The primaries are added in the reverse order, then the secondaries. 475 int fill_p = primaries->length(); 476 for (int j = 0; j < fill_p; j++) { 477 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order. 478 } 479 for( int j = 0; j < secondaries->length(); j++ ) { 480 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end. 481 } 482 #ifdef ASSERT 483 // We must not copy any null placeholders left over from bootstrap. 484 for (int j = 0; j < secondary_supers->length(); j++) { 485 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order"); 486 } 487 #endif 488 489 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array 490 return secondary_supers; 491 } 492 493 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) { 494 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed 495 } 496 497 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) { 498 uint8_t hash = k->hash_slot(); 499 if (hash > 0) { 500 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash)); 501 } 502 return 0; 503 } 504 505 506 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) { 507 if (k == nullptr) { 508 set_super(nullptr); 509 _primary_supers[0] = this; 510 assert(super_depth() == 0, "Object must already be initialized properly"); 511 } else if (k != super() || k == vmClasses::Object_klass()) { 512 assert(super() == nullptr || super() == vmClasses::Object_klass(), 513 "initialize this only once to a non-trivial value"); 514 set_super(k); 515 Klass* sup = k; 516 int sup_depth = sup->super_depth(); 517 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit()); 518 if (!can_be_primary_super_slow()) 519 my_depth = primary_super_limit(); 520 for (juint i = 0; i < my_depth; i++) { 521 _primary_supers[i] = sup->_primary_supers[i]; 522 } 523 Klass* *super_check_cell; 524 if (my_depth < primary_super_limit()) { 525 _primary_supers[my_depth] = this; 526 super_check_cell = &_primary_supers[my_depth]; 527 } else { 528 // Overflow of the primary_supers array forces me to be secondary. 529 super_check_cell = &_secondary_super_cache; 530 } 531 set_super_check_offset(u4((address)super_check_cell - (address) this)); 532 533 #ifdef ASSERT 534 { 535 juint j = super_depth(); 536 assert(j == my_depth, "computed accessor gets right answer"); 537 Klass* t = this; 538 while (!t->can_be_primary_super()) { 539 t = t->super(); 540 j = t->super_depth(); 541 } 542 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) { 543 assert(primary_super_of_depth(j1) == nullptr, "super list padding"); 544 } 545 while (t != nullptr) { 546 assert(primary_super_of_depth(j) == t, "super list initialization"); 547 t = t->super(); 548 --j; 549 } 550 assert(j == (juint)-1, "correct depth count"); 551 } 552 #endif 553 } 554 555 if (secondary_supers() == nullptr) { 556 557 // Now compute the list of secondary supertypes. 558 // Secondaries can occasionally be on the super chain, 559 // if the inline "_primary_supers" array overflows. 560 int extras = 0; 561 Klass* p; 562 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) { 563 ++extras; 564 } 565 566 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below 567 568 // Compute the "real" non-extra secondaries. 569 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces); 570 if (secondaries == nullptr) { 571 // secondary_supers set by compute_secondary_supers 572 return; 573 } 574 575 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras); 576 577 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) { 578 int i; // Scan for overflow primaries being duplicates of 2nd'arys 579 580 // This happens frequently for very deeply nested arrays: the 581 // primary superclass chain overflows into the secondary. The 582 // secondary list contains the element_klass's secondaries with 583 // an extra array dimension added. If the element_klass's 584 // secondary list already contains some primary overflows, they 585 // (with the extra level of array-ness) will collide with the 586 // normal primary superclass overflows. 587 for( i = 0; i < secondaries->length(); i++ ) { 588 if( secondaries->at(i) == p ) 589 break; 590 } 591 if( i < secondaries->length() ) 592 continue; // It's a dup, don't put it in 593 primaries->push(p); 594 } 595 // Combine the two arrays into a metadata object to pack the array. 596 uintx bitmap = 0; 597 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK); 598 set_secondary_supers(s2, bitmap); 599 } 600 } 601 602 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots, 603 Array<InstanceKlass*>* transitive_interfaces) { 604 assert(num_extra_slots == 0, "override for complex klasses"); 605 assert(transitive_interfaces == nullptr, "sanity"); 606 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap()); 607 return nullptr; 608 } 609 610 611 // subklass links. Used by the compiler (and vtable initialization) 612 // May be cleaned concurrently, so must use the Compile_lock. 613 Klass* Klass::subklass() const { 614 // Need load_acquire on the _subklass, because it races with inserts that 615 // publishes freshly initialized data. 616 for (Klass* chain = AtomicAccess::load_acquire(&_subklass); 617 chain != nullptr; 618 // Do not need load_acquire on _next_sibling, because inserts never 619 // create _next_sibling edges to dead data. 620 chain = AtomicAccess::load(&chain->_next_sibling)) 621 { 622 if (chain->is_loader_alive()) { 623 return chain; 624 } 625 } 626 return nullptr; 627 } 628 629 Klass* Klass::next_sibling(bool log) const { 630 // Do not need load_acquire on _next_sibling, because inserts never 631 // create _next_sibling edges to dead data. 632 for (Klass* chain = AtomicAccess::load(&_next_sibling); 633 chain != nullptr; 634 chain = AtomicAccess::load(&chain->_next_sibling)) { 635 // Only return alive klass, there may be stale klass 636 // in this chain if cleaned concurrently. 637 if (chain->is_loader_alive()) { 638 return chain; 639 } else if (log) { 640 if (log_is_enabled(Trace, class, unload)) { 641 ResourceMark rm; 642 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name()); 643 } 644 } 645 } 646 return nullptr; 647 } 648 649 void Klass::set_subklass(Klass* s) { 650 assert(s != this, "sanity check"); 651 AtomicAccess::release_store(&_subklass, s); 652 } 653 654 void Klass::set_next_sibling(Klass* s) { 655 assert(s != this, "sanity check"); 656 // Does not need release semantics. If used by cleanup, it will link to 657 // already safely published data, and if used by inserts, will be published 658 // safely using cmpxchg. 659 AtomicAccess::store(&_next_sibling, s); 660 } 661 662 void Klass::append_to_sibling_list() { 663 if (Universe::is_fully_initialized()) { 664 assert_locked_or_safepoint(Compile_lock); 665 } 666 DEBUG_ONLY(verify();) 667 // add ourselves to super' subklass list 668 InstanceKlass* super = java_super(); 669 if (super == nullptr) return; // special case: class Object 670 assert((!super->is_interface() // interfaces cannot be supers 671 && (super->java_super() == nullptr || !is_interface())), 672 "an interface can only be a subklass of Object"); 673 674 // Make sure there is no stale subklass head 675 super->clean_subklass(); 676 677 for (;;) { 678 Klass* prev_first_subklass = AtomicAccess::load_acquire(&_super->_subklass); 679 if (prev_first_subklass != nullptr) { 680 // set our sibling to be the super' previous first subklass 681 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses"); 682 set_next_sibling(prev_first_subklass); 683 } 684 // Note that the prev_first_subklass is always alive, meaning no sibling_next links 685 // are ever created to not alive klasses. This is an important invariant of the lock-free 686 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list. 687 if (AtomicAccess::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) { 688 return; 689 } 690 } 691 DEBUG_ONLY(verify();) 692 } 693 694 // The log parameter is for clean_weak_klass_links to report unlinked classes. 695 Klass* Klass::clean_subklass(bool log) { 696 for (;;) { 697 // Need load_acquire, due to contending with concurrent inserts 698 Klass* subklass = AtomicAccess::load_acquire(&_subklass); 699 if (subklass == nullptr || subklass->is_loader_alive()) { 700 return subklass; 701 } 702 if (log && log_is_enabled(Trace, class, unload)) { 703 ResourceMark rm; 704 log_trace(class, unload)("unlinking class (subclass): %s", subklass->external_name()); 705 } 706 // Try to fix _subklass until it points at something not dead. 707 AtomicAccess::cmpxchg(&_subklass, subklass, subklass->next_sibling(log)); 708 } 709 } 710 711 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) { 712 if (!ClassUnloading || !unloading_occurred) { 713 return; 714 } 715 716 Klass* root = vmClasses::Object_klass(); 717 Stack<Klass*, mtGC> stack; 718 719 stack.push(root); 720 while (!stack.is_empty()) { 721 Klass* current = stack.pop(); 722 723 assert(current->is_loader_alive(), "just checking, this should be live"); 724 725 // Find and set the first alive subklass 726 Klass* sub = current->clean_subklass(true); 727 if (sub != nullptr) { 728 stack.push(sub); 729 } 730 731 // Find and set the first alive sibling 732 Klass* sibling = current->next_sibling(true); 733 current->set_next_sibling(sibling); 734 if (sibling != nullptr) { 735 stack.push(sibling); 736 } 737 738 // Clean the implementors list and method data. 739 if (clean_alive_klasses && current->is_instance_klass()) { 740 InstanceKlass* ik = InstanceKlass::cast(current); 741 clean_weak_instanceklass_links(ik); 742 } 743 } 744 } 745 746 void Klass::clean_weak_instanceklass_links(InstanceKlass* ik) { 747 ik->clean_weak_instanceklass_links(); 748 // JVMTI RedefineClasses creates previous versions that are not in 749 // the class hierarchy, so process them here. 750 while ((ik = ik->previous_versions()) != nullptr) { 751 ik->clean_weak_instanceklass_links(); 752 } 753 } 754 755 void Klass::metaspace_pointers_do(MetaspaceClosure* it) { 756 if (log_is_enabled(Trace, aot)) { 757 ResourceMark rm; 758 log_trace(aot)("Iter(Klass): %p (%s)", this, external_name()); 759 } 760 761 it->push(&_name); 762 it->push(&_secondary_supers); 763 for (int i = 0; i < _primary_super_limit; i++) { 764 it->push(&_primary_supers[i]); 765 } 766 it->push(&_super); 767 if (!CDSConfig::is_dumping_archive()) { 768 // If dumping archive, these may point to excluded classes. There's no need 769 // to follow these pointers anyway, as they will be set to null in 770 // remove_unshareable_info(). 771 it->push((Klass**)&_subklass); 772 it->push((Klass**)&_next_sibling); 773 it->push(&_next_link); 774 } 775 776 vtableEntry* vt = start_of_vtable(); 777 for (int i=0; i<vtable_length(); i++) { 778 it->push(vt[i].method_addr()); 779 } 780 } 781 782 #if INCLUDE_CDS 783 void Klass::remove_unshareable_info() { 784 assert(CDSConfig::is_dumping_archive(), 785 "only called during CDS dump time"); 786 JFR_ONLY(REMOVE_ID(this);) 787 if (log_is_enabled(Trace, aot, unshareable)) { 788 ResourceMark rm; 789 log_trace(aot, unshareable)("remove: %s", external_name()); 790 } 791 792 // _secondary_super_cache may be updated by an is_subtype_of() call 793 // while ArchiveBuilder is copying metaspace objects. Let's reset it to 794 // null and let it be repopulated at runtime. 795 set_secondary_super_cache(nullptr); 796 797 set_subklass(nullptr); 798 set_next_sibling(nullptr); 799 set_next_link(nullptr); 800 801 // Null out class_loader_data because we don't share that yet. 802 set_class_loader_data(nullptr); 803 set_in_aot_cache(); 804 805 if (CDSConfig::is_dumping_classic_static_archive()) { 806 // "Classic" static archives are required to have deterministic contents. 807 // The elements in _secondary_supers are addresses in the ArchiveBuilder 808 // output buffer, so they should have deterministic values. If we rehash 809 // _secondary_supers, its elements will appear in a deterministic order. 810 // 811 // Note that the bitmap is guaranteed to be deterministic, regardless of the 812 // actual addresses of the elements in _secondary_supers. So rehashing shouldn't 813 // change it. 814 uintx bitmap = hash_secondary_supers(secondary_supers(), true); 815 assert(bitmap == _secondary_supers_bitmap, "bitmap should not be changed due to rehashing"); 816 } 817 } 818 819 void Klass::remove_java_mirror() { 820 assert(CDSConfig::is_dumping_archive(), "sanity"); 821 if (log_is_enabled(Trace, aot, unshareable)) { 822 ResourceMark rm; 823 log_trace(aot, unshareable)("remove java_mirror: %s", external_name()); 824 } 825 826 #if INCLUDE_CDS_JAVA_HEAP 827 _archived_mirror_index = -1; 828 if (CDSConfig::is_dumping_heap()) { 829 Klass* src_k = ArchiveBuilder::current()->get_source_addr(this); 830 oop orig_mirror = src_k->java_mirror(); 831 if (orig_mirror == nullptr) { 832 assert(CDSConfig::is_dumping_final_static_archive(), "sanity"); 833 if (is_instance_klass()) { 834 assert(InstanceKlass::cast(this)->defined_by_other_loaders(), "sanity"); 835 } else { 836 precond(is_objArray_klass()); 837 Klass *k = ObjArrayKlass::cast(this)->bottom_klass(); 838 precond(k->is_instance_klass()); 839 assert(InstanceKlass::cast(k)->defined_by_other_loaders(), "sanity"); 840 } 841 } else { 842 oop scratch_mirror = HeapShared::scratch_java_mirror(orig_mirror); 843 if (scratch_mirror != nullptr) { 844 _archived_mirror_index = HeapShared::append_root(scratch_mirror); 845 } 846 } 847 } 848 #endif 849 850 // Just null out the mirror. The class_loader_data() no longer exists. 851 clear_java_mirror_handle(); 852 } 853 854 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) { 855 assert(is_klass(), "ensure C++ vtable is restored"); 856 assert(in_aot_cache(), "must be set"); 857 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be"); 858 if (log_is_enabled(Trace, aot, unshareable)) { 859 ResourceMark rm(THREAD); 860 oop class_loader = loader_data->class_loader(); 861 log_trace(aot, unshareable)("restore: %s with class loader: %s", external_name(), 862 class_loader != nullptr ? class_loader->klass()->external_name() : "boot"); 863 } 864 865 // If an exception happened during CDS restore, some of these fields may already be 866 // set. We leave the class on the CLD list, even if incomplete so that we don't 867 // modify the CLD list outside a safepoint. 868 if (class_loader_data() == nullptr) { 869 set_class_loader_data(loader_data); 870 } 871 872 // Add to class loader list first before creating the mirror 873 // (same order as class file parsing) 874 loader_data->add_class(this); 875 876 JFR_ONLY(Jfr::on_restoration(this, THREAD);) 877 878 Handle loader(THREAD, loader_data->class_loader()); 879 ModuleEntry* module_entry = nullptr; 880 Klass* k = this; 881 if (k->is_objArray_klass()) { 882 k = ObjArrayKlass::cast(k)->bottom_klass(); 883 } 884 // Obtain klass' module. 885 if (k->is_instance_klass()) { 886 InstanceKlass* ik = (InstanceKlass*) k; 887 module_entry = ik->module(); 888 } else { 889 module_entry = ModuleEntryTable::javabase_moduleEntry(); 890 } 891 // Obtain java.lang.Module, if available 892 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module_oop() : (oop)nullptr)); 893 894 if (this->has_archived_mirror_index()) { 895 ResourceMark rm(THREAD); 896 log_debug(aot, mirror)("%s has raw archived mirror", external_name()); 897 if (HeapShared::is_archived_heap_in_use()) { 898 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle, 899 protection_domain, 900 CHECK); 901 if (present) { 902 return; 903 } 904 } 905 906 // No archived mirror data 907 log_debug(aot, mirror)("No archived mirror data for %s", external_name()); 908 clear_java_mirror_handle(); 909 this->clear_archived_mirror_index(); 910 } 911 912 // Only recreate it if not present. A previous attempt to restore may have 913 // gotten an OOM later but keep the mirror if it was created. 914 if (java_mirror() == nullptr) { 915 ResourceMark rm(THREAD); 916 log_trace(aot, mirror)("Recreate mirror for %s", external_name()); 917 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK); 918 } 919 } 920 #endif // INCLUDE_CDS 921 922 #if INCLUDE_CDS_JAVA_HEAP 923 oop Klass::archived_java_mirror() { 924 assert(has_archived_mirror_index(), "must have archived mirror"); 925 return HeapShared::get_root(_archived_mirror_index); 926 } 927 928 void Klass::clear_archived_mirror_index() { 929 if (_archived_mirror_index >= 0) { 930 HeapShared::clear_root(_archived_mirror_index); 931 } 932 _archived_mirror_index = -1; 933 } 934 #endif // INCLUDE_CDS_JAVA_HEAP 935 936 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) { 937 if (length > max_length) { 938 if (!THREAD->is_in_internal_oome_mark()) { 939 report_java_out_of_memory("Requested array size exceeds VM limit"); 940 JvmtiExport::post_array_size_exhausted(); 941 THROW_OOP(Universe::out_of_memory_error_array_size()); 942 } else { 943 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace()); 944 } 945 } else if (length < 0) { 946 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length)); 947 } 948 } 949 950 // Replace the last '+' char with '/'. 951 static char* convert_hidden_name_to_java(Symbol* name) { 952 size_t name_len = name->utf8_length(); 953 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1); 954 name->as_klass_external_name(result, (int)name_len + 1); 955 for (int index = (int)name_len; index > 0; index--) { 956 if (result[index] == '+') { 957 result[index] = JVM_SIGNATURE_SLASH; 958 break; 959 } 960 } 961 return result; 962 } 963 964 // In product mode, this function doesn't have virtual function calls so 965 // there might be some performance advantage to handling InstanceKlass here. 966 const char* Klass::external_name() const { 967 if (is_instance_klass()) { 968 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this); 969 if (ik->is_hidden()) { 970 char* result = convert_hidden_name_to_java(name()); 971 return result; 972 } 973 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) { 974 char* result = convert_hidden_name_to_java(name()); 975 return result; 976 } 977 if (name() == nullptr) return "<unknown>"; 978 return name()->as_klass_external_name(); 979 } 980 981 const char* Klass::signature_name() const { 982 if (name() == nullptr) return "<unknown>"; 983 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) { 984 size_t name_len = name()->utf8_length(); 985 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1); 986 name()->as_C_string(result, (int)name_len + 1); 987 for (int index = (int)name_len; index > 0; index--) { 988 if (result[index] == '+') { 989 result[index] = JVM_SIGNATURE_DOT; 990 break; 991 } 992 } 993 return result; 994 } 995 return name()->as_C_string(); 996 } 997 998 const char* Klass::external_kind() const { 999 if (is_interface()) return "interface"; 1000 if (is_abstract()) return "abstract class"; 1001 return "class"; 1002 } 1003 1004 // Unless overridden, jvmti_class_status has no flags set. 1005 jint Klass::jvmti_class_status() const { 1006 return 0; 1007 } 1008 1009 1010 // Printing 1011 1012 void Klass::print_on(outputStream* st) const { 1013 ResourceMark rm; 1014 // print title 1015 st->print("%s", internal_name()); 1016 print_address_on(st); 1017 st->cr(); 1018 } 1019 1020 #define BULLET " - " 1021 1022 // Caller needs ResourceMark 1023 void Klass::oop_print_on(oop obj, outputStream* st) { 1024 // print title 1025 st->print_cr("%s ", internal_name()); 1026 obj->print_address_on(st); 1027 1028 if (WizardMode) { 1029 // print header 1030 obj->mark().print_on(st); 1031 st->cr(); 1032 if (UseCompactObjectHeaders) { 1033 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value()); 1034 st->cr(); 1035 } 1036 } 1037 1038 // print class 1039 st->print(BULLET"klass: "); 1040 obj->klass()->print_value_on(st); 1041 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr(); 1042 st->cr(); 1043 } 1044 1045 void Klass::oop_print_value_on(oop obj, outputStream* st) { 1046 // print title 1047 ResourceMark rm; // Cannot print in debug mode without this 1048 st->print("%s", internal_name()); 1049 obj->print_address_on(st); 1050 } 1051 1052 // Verification 1053 1054 void Klass::verify_on(outputStream* st) { 1055 1056 // This can be expensive, but it is worth checking that this klass is actually 1057 // in the CLD graph but not in production. 1058 #ifdef ASSERT 1059 if (UseCompressedClassPointers) { 1060 // Stricter checks for both correct alignment and placement 1061 CompressedKlassPointers::check_encodable(this); 1062 } else { 1063 assert(Metaspace::contains((address)this), "Should be"); 1064 } 1065 #endif // ASSERT 1066 1067 guarantee(this->is_klass(),"should be klass"); 1068 1069 if (super() != nullptr) { 1070 guarantee(super()->is_klass(), "should be klass"); 1071 } 1072 if (secondary_super_cache() != nullptr) { 1073 Klass* ko = secondary_super_cache(); 1074 guarantee(ko->is_klass(), "should be klass"); 1075 } 1076 for ( uint i = 0; i < primary_super_limit(); i++ ) { 1077 Klass* ko = _primary_supers[i]; 1078 if (ko != nullptr) { 1079 guarantee(ko->is_klass(), "should be klass"); 1080 } 1081 } 1082 1083 if (java_mirror_no_keepalive() != nullptr) { 1084 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance"); 1085 } 1086 } 1087 1088 void Klass::oop_verify_on(oop obj, outputStream* st) { 1089 guarantee(oopDesc::is_oop(obj), "should be oop"); 1090 guarantee(obj->klass()->is_klass(), "klass field is not a klass"); 1091 } 1092 1093 // Note: this function is called with an address that may or may not be a Klass. 1094 // The point is not to assert it is but to check if it could be. 1095 bool Klass::is_valid(Klass* k) { 1096 if (!is_aligned(k, sizeof(MetaWord))) return false; 1097 if ((size_t)k < os::min_page_size()) return false; 1098 1099 if (!os::is_readable_range(k, k + 1)) return false; 1100 if (!Metaspace::contains(k)) return false; 1101 1102 if (!Symbol::is_valid(k->name())) return false; 1103 return ClassLoaderDataGraph::is_valid(k->class_loader_data()); 1104 } 1105 1106 Method* Klass::method_at_vtable(int index) { 1107 #ifndef PRODUCT 1108 assert(index >= 0, "valid vtable index"); 1109 if (DebugVtables) { 1110 verify_vtable_index(index); 1111 } 1112 #endif 1113 return start_of_vtable()[index].method(); 1114 } 1115 1116 1117 #ifndef PRODUCT 1118 1119 bool Klass::verify_vtable_index(int i) { 1120 int limit = vtable_length()/vtableEntry::size(); 1121 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit); 1122 return true; 1123 } 1124 1125 #endif // PRODUCT 1126 1127 // Caller needs ResourceMark 1128 // joint_in_module_of_loader provides an optimization if 2 classes are in 1129 // the same module to succinctly print out relevant information about their 1130 // module name and class loader's name_and_id for error messages. 1131 // Format: 1132 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2> 1133 // are in module <module-name>[@<version>] 1134 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>] 1135 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const { 1136 assert(module() == class2->module(), "classes do not have the same module"); 1137 const char* class1_name = external_name(); 1138 size_t len = strlen(class1_name) + 1; 1139 1140 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader); 1141 len += strlen(class2_description); 1142 1143 len += strlen(" and "); 1144 1145 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len); 1146 1147 // Just return the FQN if error when allocating string 1148 if (joint_description == nullptr) { 1149 return class1_name; 1150 } 1151 1152 jio_snprintf(joint_description, len, "%s and %s", 1153 class1_name, 1154 class2_description); 1155 1156 return joint_description; 1157 } 1158 1159 // Caller needs ResourceMark 1160 // class_in_module_of_loader provides a standard way to include 1161 // relevant information about a class, such as its module name as 1162 // well as its class loader's name_and_id, in error messages and logging. 1163 // Format: 1164 // <fully-qualified-external-class-name> is in module <module-name>[@<version>] 1165 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>] 1166 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const { 1167 // 1. fully qualified external name of class 1168 const char* klass_name = external_name(); 1169 size_t len = strlen(klass_name) + 1; 1170 1171 // 2. module name + @version 1172 const char* module_name = ""; 1173 const char* version = ""; 1174 bool has_version = false; 1175 bool module_is_named = false; 1176 const char* module_name_phrase = ""; 1177 const Klass* bottom_klass = is_objArray_klass() ? 1178 ObjArrayKlass::cast(this)->bottom_klass() : this; 1179 if (bottom_klass->is_instance_klass()) { 1180 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module(); 1181 if (module->is_named()) { 1182 module_is_named = true; 1183 module_name_phrase = "module "; 1184 module_name = module->name()->as_C_string(); 1185 len += strlen(module_name); 1186 // Use version if exists and is not a jdk module 1187 if (module->should_show_version()) { 1188 has_version = true; 1189 version = module->version()->as_C_string(); 1190 // Include stlen(version) + 1 for the "@" 1191 len += strlen(version) + 1; 1192 } 1193 } else { 1194 module_name = UNNAMED_MODULE; 1195 len += UNNAMED_MODULE_LEN; 1196 } 1197 } else { 1198 // klass is an array of primitives, module is java.base 1199 module_is_named = true; 1200 module_name_phrase = "module "; 1201 module_name = JAVA_BASE_NAME; 1202 len += JAVA_BASE_NAME_LEN; 1203 } 1204 1205 // 3. class loader's name_and_id 1206 ClassLoaderData* cld = class_loader_data(); 1207 assert(cld != nullptr, "class_loader_data should not be null"); 1208 const char* loader_name_and_id = cld->loader_name_and_id(); 1209 len += strlen(loader_name_and_id); 1210 1211 // 4. include parent loader information 1212 const char* parent_loader_phrase = ""; 1213 const char* parent_loader_name_and_id = ""; 1214 if (include_parent_loader && 1215 !cld->is_builtin_class_loader_data()) { 1216 oop parent_loader = java_lang_ClassLoader::parent(class_loader()); 1217 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader); 1218 // The parent loader's ClassLoaderData could be null if it is 1219 // a delegating class loader that has never defined a class. 1220 // In this case the loader's name must be obtained via the parent loader's oop. 1221 if (parent_cld == nullptr) { 1222 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader); 1223 if (cl_name_and_id != nullptr) { 1224 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id); 1225 } 1226 } else { 1227 parent_loader_name_and_id = parent_cld->loader_name_and_id(); 1228 } 1229 parent_loader_phrase = ", parent loader "; 1230 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id); 1231 } 1232 1233 // Start to construct final full class description string 1234 len += ((use_are) ? strlen(" are in ") : strlen(" is in ")); 1235 len += strlen(module_name_phrase) + strlen(" of loader "); 1236 1237 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len); 1238 1239 // Just return the FQN if error when allocating string 1240 if (class_description == nullptr) { 1241 return klass_name; 1242 } 1243 1244 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s", 1245 klass_name, 1246 (use_are) ? "are" : "is", 1247 module_name_phrase, 1248 module_name, 1249 (has_version) ? "@" : "", 1250 (has_version) ? version : "", 1251 loader_name_and_id, 1252 parent_loader_phrase, 1253 parent_loader_name_and_id); 1254 1255 return class_description; 1256 } 1257 1258 class LookupStats : StackObj { 1259 private: 1260 uint _no_of_samples; 1261 uint _worst; 1262 uint _worst_count; 1263 uint _average; 1264 uint _best; 1265 uint _best_count; 1266 public: 1267 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {} 1268 1269 ~LookupStats() { 1270 assert(_best <= _worst || _no_of_samples == 0, "sanity"); 1271 } 1272 1273 void sample(uint value) { 1274 ++_no_of_samples; 1275 _average += value; 1276 1277 if (_worst < value) { 1278 _worst = value; 1279 _worst_count = 1; 1280 } else if (_worst == value) { 1281 ++_worst_count; 1282 } 1283 1284 if (_best > value) { 1285 _best = value; 1286 _best_count = 1; 1287 } else if (_best == value) { 1288 ++_best_count; 1289 } 1290 } 1291 1292 void print_on(outputStream* st) const { 1293 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples); 1294 if (_best_count < _no_of_samples) { 1295 st->print("; average: %4.1f; worst: %2d (%4.1f%%)", 1296 (1.0 * _average) / _no_of_samples, 1297 _worst, (100.0 * _worst_count) / _no_of_samples); 1298 } 1299 } 1300 }; 1301 1302 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) { 1303 int num_of_supers = secondary_supers->length(); 1304 1305 LookupStats s; 1306 for (int i = 0; i < num_of_supers; i++) { 1307 Klass* secondary_super = secondary_supers->at(i); 1308 int home_slot = Klass::compute_home_slot(secondary_super, bitmap); 1309 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK); 1310 s.sample(score); 1311 } 1312 st->print("positive_lookup: "); s.print_on(st); 1313 } 1314 1315 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) { 1316 assert(~bitmap != 0, "no zeroes"); 1317 uintx start = rotate_right(bitmap, slot); 1318 return count_trailing_zeros(~start); 1319 } 1320 1321 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) { 1322 LookupStats s; 1323 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) { 1324 uint score = compute_distance_to_nearest_zero(slot, bitmap); 1325 s.sample(score); 1326 } 1327 st->print("negative_lookup: "); s.print_on(st); 1328 } 1329 1330 void Klass::print_secondary_supers_on(outputStream* st) const { 1331 if (secondary_supers() != nullptr) { 1332 st->print(" - "); st->print("%d elements;", _secondary_supers->length()); 1333 st->print_cr(" bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap); 1334 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY && 1335 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) { 1336 st->print(" - "); print_positive_lookup_stats(secondary_supers(), 1337 _secondary_supers_bitmap, st); st->cr(); 1338 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr(); 1339 } 1340 } else { 1341 st->print("null"); 1342 } 1343 } 1344 1345 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) { 1346 ResourceMark rm; 1347 super->print(); 1348 sub->print(); 1349 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d", 1350 msg, sub->external_name(), super->external_name(), linear_result, table_result); 1351 } --- EOF ---