1 /* 2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "cds/archiveHeapLoader.hpp" 26 #include "cds/cdsConfig.hpp" 27 #include "cds/heapShared.hpp" 28 #include "classfile/classLoader.hpp" 29 #include "classfile/classLoaderData.inline.hpp" 30 #include "classfile/classLoaderDataGraph.inline.hpp" 31 #include "classfile/javaClasses.inline.hpp" 32 #include "classfile/moduleEntry.hpp" 33 #include "classfile/systemDictionary.hpp" 34 #include "classfile/systemDictionaryShared.hpp" 35 #include "classfile/vmClasses.hpp" 36 #include "classfile/vmSymbols.hpp" 37 #include "gc/shared/collectedHeap.inline.hpp" 38 #include "jvm_io.h" 39 #include "logging/log.hpp" 40 #include "memory/metadataFactory.hpp" 41 #include "memory/metaspaceClosure.hpp" 42 #include "memory/oopFactory.hpp" 43 #include "memory/resourceArea.hpp" 44 #include "memory/universe.hpp" 45 #include "oops/compressedKlass.inline.hpp" 46 #include "oops/compressedOops.inline.hpp" 47 #include "oops/instanceKlass.hpp" 48 #include "oops/klass.inline.hpp" 49 #include "oops/objArrayKlass.hpp" 50 #include "oops/oop.inline.hpp" 51 #include "oops/oopHandle.inline.hpp" 52 #include "prims/jvmtiExport.hpp" 53 #include "runtime/atomic.hpp" 54 #include "runtime/handles.inline.hpp" 55 #include "runtime/perfData.hpp" 56 #include "utilities/macros.hpp" 57 #include "utilities/powerOfTwo.hpp" 58 #include "utilities/rotate_bits.hpp" 59 #include "utilities/stack.inline.hpp" 60 61 void Klass::set_java_mirror(Handle m) { 62 assert(!m.is_null(), "New mirror should never be null."); 63 assert(_java_mirror.is_empty(), "should only be used to initialize mirror"); 64 _java_mirror = class_loader_data()->add_handle(m); 65 } 66 67 bool Klass::is_cloneable() const { 68 return _misc_flags.is_cloneable_fast() || 69 is_subtype_of(vmClasses::Cloneable_klass()); 70 } 71 72 void Klass::set_is_cloneable() { 73 if (name() == vmSymbols::java_lang_invoke_MemberName()) { 74 assert(is_final(), "no subclasses allowed"); 75 // MemberName cloning should not be intrinsified and always happen in JVM_Clone. 76 } else if (is_instance_klass() && InstanceKlass::cast(this)->reference_type() != REF_NONE) { 77 // Reference cloning should not be intrinsified and always happen in JVM_Clone. 78 } else { 79 _misc_flags.set_is_cloneable_fast(true); 80 } 81 } 82 83 uint8_t Klass::compute_hash_slot(Symbol* n) { 84 uint hash_code; 85 // Special cases for the two superclasses of all Array instances. 86 // Code elsewhere assumes, for all instances of ArrayKlass, that 87 // these two interfaces will be in this order. 88 89 // We ensure there are some empty slots in the hash table between 90 // these two very common interfaces because if they were adjacent 91 // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1 92 // would result in a probe length of 3. 93 if (n == vmSymbols::java_lang_Cloneable()) { 94 hash_code = 0; 95 } else if (n == vmSymbols::java_io_Serializable()) { 96 hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2; 97 } else { 98 auto s = (const jbyte*) n->bytes(); 99 hash_code = java_lang_String::hash_code(s, n->utf8_length()); 100 // We use String::hash_code here (rather than e.g. 101 // Symbol::identity_hash()) in order to have a hash code that 102 // does not change from run to run. We want that because the 103 // hash value for a secondary superclass appears in generated 104 // code as a constant. 105 106 // This constant is magic: see Knuth, "Fibonacci Hashing". 107 constexpr uint multiplier 108 = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 )) 109 constexpr uint hash_shift = sizeof(hash_code) * 8 - 6; 110 // The leading bits of the least significant half of the product. 111 hash_code = (hash_code * multiplier) >> hash_shift; 112 113 if (StressSecondarySupers) { 114 // Generate many hash collisions in order to stress-test the 115 // linear search fallback. 116 hash_code = hash_code % 3; 117 hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3); 118 } 119 } 120 121 return (hash_code & SECONDARY_SUPERS_TABLE_MASK); 122 } 123 124 void Klass::set_name(Symbol* n) { 125 _name = n; 126 127 if (_name != nullptr) { 128 _name->increment_refcount(); 129 } 130 131 { 132 elapsedTimer selftime; 133 selftime.start(); 134 135 _hash_slot = compute_hash_slot(n); 136 assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required"); 137 138 selftime.stop(); 139 if (UsePerfData) { 140 ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks()); 141 } 142 } 143 144 if (CDSConfig::is_dumping_archive() && is_instance_klass()) { 145 SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this)); 146 } 147 } 148 149 bool Klass::is_subclass_of(const Klass* k) const { 150 // Run up the super chain and check 151 if (this == k) return true; 152 153 Klass* t = const_cast<Klass*>(this)->super(); 154 155 while (t != nullptr) { 156 if (t == k) return true; 157 t = t->super(); 158 } 159 return false; 160 } 161 162 void Klass::release_C_heap_structures(bool release_constant_pool) { 163 if (_name != nullptr) _name->decrement_refcount(); 164 } 165 166 bool Klass::linear_search_secondary_supers(const Klass* k) const { 167 // Scan the array-of-objects for a match 168 // FIXME: We could do something smarter here, maybe a vectorized 169 // comparison or a binary search, but is that worth any added 170 // complexity? 171 int cnt = secondary_supers()->length(); 172 for (int i = 0; i < cnt; i++) { 173 if (secondary_supers()->at(i) == k) { 174 return true; 175 } 176 } 177 return false; 178 } 179 180 // Given a secondary superklass k, an initial array index, and an 181 // occupancy bitmap rotated such that Bit 1 is the next bit to test, 182 // search for k. 183 bool Klass::fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const { 184 // Once the occupancy bitmap is almost full, it's faster to use a 185 // linear search. 186 if (secondary_supers()->length() > SECONDARY_SUPERS_TABLE_SIZE - 2) { 187 return linear_search_secondary_supers(k); 188 } 189 190 // This is conventional linear probing, but instead of terminating 191 // when a null entry is found in the table, we maintain a bitmap 192 // in which a 0 indicates missing entries. 193 194 precond((int)population_count(rotated_bitmap) == secondary_supers()->length()); 195 196 // The check for secondary_supers()->length() <= SECONDARY_SUPERS_TABLE_SIZE - 2 197 // at the start of this function guarantees there are 0s in the 198 // bitmap, so this loop eventually terminates. 199 while ((rotated_bitmap & 2) != 0) { 200 if (++index == secondary_supers()->length()) { 201 index = 0; 202 } 203 if (secondary_supers()->at(index) == k) { 204 return true; 205 } 206 rotated_bitmap = rotate_right(rotated_bitmap, 1); 207 } 208 return false; 209 } 210 211 // Return self, except for abstract classes with exactly 1 212 // implementor. Then return the 1 concrete implementation. 213 Klass *Klass::up_cast_abstract() { 214 Klass *r = this; 215 while( r->is_abstract() ) { // Receiver is abstract? 216 Klass *s = r->subklass(); // Check for exactly 1 subklass 217 if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up 218 return this; // Return 'this' as a no-progress flag 219 r = s; // Loop till find concrete class 220 } 221 return r; // Return the 1 concrete class 222 } 223 224 // Find LCA in class hierarchy 225 Klass *Klass::LCA( Klass *k2 ) { 226 Klass *k1 = this; 227 while( 1 ) { 228 if( k1->is_subtype_of(k2) ) return k2; 229 if( k2->is_subtype_of(k1) ) return k1; 230 k1 = k1->super(); 231 k2 = k2->super(); 232 } 233 } 234 235 236 void Klass::check_valid_for_instantiation(bool throwError, TRAPS) { 237 ResourceMark rm(THREAD); 238 THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError() 239 : vmSymbols::java_lang_InstantiationException(), external_name()); 240 } 241 242 243 void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) { 244 ResourceMark rm(THREAD); 245 assert(s != nullptr, "Throw NPE!"); 246 THROW_MSG(vmSymbols::java_lang_ArrayStoreException(), 247 err_msg("arraycopy: source type %s is not an array", s->klass()->external_name())); 248 } 249 250 251 void Klass::initialize(TRAPS) { 252 ShouldNotReachHere(); 253 } 254 255 Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const { 256 #ifdef ASSERT 257 tty->print_cr("Error: find_field called on a klass oop." 258 " Likely error: reflection method does not correctly" 259 " wrap return value in a mirror object."); 260 #endif 261 ShouldNotReachHere(); 262 return nullptr; 263 } 264 265 Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature, 266 OverpassLookupMode overpass_mode, 267 PrivateLookupMode private_mode) const { 268 #ifdef ASSERT 269 tty->print_cr("Error: uncached_lookup_method called on a klass oop." 270 " Likely error: reflection method does not correctly" 271 " wrap return value in a mirror object."); 272 #endif 273 ShouldNotReachHere(); 274 return nullptr; 275 } 276 277 static markWord make_prototype(const Klass* kls) { 278 markWord prototype = markWord::prototype(); 279 #ifdef _LP64 280 if (UseCompactObjectHeaders) { 281 // With compact object headers, the narrow Klass ID is part of the mark word. 282 // We therfore seed the mark word with the narrow Klass ID. 283 // Note that only those Klass that can be instantiated have a narrow Klass ID. 284 // For those who don't, we leave the klass bits empty and assert if someone 285 // tries to use those. 286 const narrowKlass nk = CompressedKlassPointers::is_encodable(kls) ? 287 CompressedKlassPointers::encode(const_cast<Klass*>(kls)) : 0; 288 prototype = prototype.set_narrow_klass(nk); 289 } 290 #endif 291 return prototype; 292 } 293 294 Klass::Klass() : _kind(UnknownKlassKind) { 295 assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds"); 296 } 297 298 // "Normal" instantiation is preceded by a MetaspaceObj allocation 299 // which zeros out memory - calloc equivalent. 300 // The constructor is also used from CppVtableCloner, 301 // which doesn't zero out the memory before calling the constructor. 302 Klass::Klass(KlassKind kind) : _kind(kind), 303 _prototype_header(make_prototype(this)), 304 _shared_class_path_index(-1) { 305 CDS_ONLY(_shared_class_flags = 0;) 306 CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;) 307 _primary_supers[0] = this; 308 set_super_check_offset(in_bytes(primary_supers_offset())); 309 } 310 311 jint Klass::array_layout_helper(BasicType etype) { 312 assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype"); 313 // Note that T_ARRAY is not allowed here. 314 int hsize = arrayOopDesc::base_offset_in_bytes(etype); 315 int esize = type2aelembytes(etype); 316 bool isobj = (etype == T_OBJECT); 317 int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value; 318 int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize)); 319 320 assert(lh < (int)_lh_neutral_value, "must look like an array layout"); 321 assert(layout_helper_is_array(lh), "correct kind"); 322 assert(layout_helper_is_objArray(lh) == isobj, "correct kind"); 323 assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind"); 324 assert(layout_helper_header_size(lh) == hsize, "correct decode"); 325 assert(layout_helper_element_type(lh) == etype, "correct decode"); 326 assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode"); 327 328 return lh; 329 } 330 331 int Klass::modifier_flags() const { 332 int mods = java_lang_Class::modifiers(java_mirror()); 333 assert(mods == compute_modifier_flags(), "should be same"); 334 return mods; 335 } 336 337 bool Klass::can_be_primary_super_slow() const { 338 if (super() == nullptr) 339 return true; 340 else if (super()->super_depth() >= primary_super_limit()-1) 341 return false; 342 else 343 return true; 344 } 345 346 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) { 347 #ifdef ASSERT 348 if (secondaries != nullptr) { 349 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries); 350 assert(bitmap == real_bitmap, "must be"); 351 assert(secondaries->length() >= (int)population_count(bitmap), "must be"); 352 } 353 #endif 354 _secondary_supers_bitmap = bitmap; 355 _secondary_supers = secondaries; 356 357 if (secondaries != nullptr) { 358 LogMessage(class, load) msg; 359 NonInterleavingLogStream log {LogLevel::Debug, msg}; 360 if (log.is_enabled()) { 361 ResourceMark rm; 362 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name()); 363 print_secondary_supers_on(&log); 364 } 365 } 366 } 367 368 // Hashed secondary superclasses 369 // 370 // We use a compressed 64-entry hash table with linear probing. We 371 // start by creating a hash table in the usual way, followed by a pass 372 // that removes all the null entries. To indicate which entries would 373 // have been null we use a bitmap that contains a 1 in each position 374 // where an entry is present, 0 otherwise. This bitmap also serves as 375 // a kind of Bloom filter, which in many cases allows us quickly to 376 // eliminate the possibility that something is a member of a set of 377 // secondaries. 378 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) { 379 const int length = secondaries->length(); 380 381 if (length == 0) { 382 return SECONDARY_SUPERS_BITMAP_EMPTY; 383 } 384 385 if (length == 1) { 386 int hash_slot = secondaries->at(0)->hash_slot(); 387 return uintx(1) << hash_slot; 388 } 389 390 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap) 391 392 // Don't attempt to hash a table that's completely full, because in 393 // the case of an absent interface linear probing would not 394 // terminate. 395 if (length >= SECONDARY_SUPERS_TABLE_SIZE) { 396 return SECONDARY_SUPERS_BITMAP_FULL; 397 } 398 399 { 400 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time()); 401 402 ResourceMark rm; 403 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY; 404 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE, 405 SECONDARY_SUPERS_TABLE_SIZE, nullptr); 406 407 for (int j = 0; j < length; j++) { 408 Klass* k = secondaries->at(j); 409 hash_insert(k, hashed_secondaries, bitmap); 410 } 411 412 // Pack the hashed secondaries array by copying it into the 413 // secondaries array, sans nulls, if modification is allowed. 414 // Otherwise, validate the order. 415 int i = 0; 416 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) { 417 bool has_element = ((bitmap >> slot) & 1) != 0; 418 assert(has_element == (hashed_secondaries->at(slot) != nullptr), ""); 419 if (has_element) { 420 Klass* k = hashed_secondaries->at(slot); 421 if (rewrite) { 422 secondaries->at_put(i, k); 423 } else if (secondaries->at(i) != k) { 424 assert(false, "broken secondary supers hash table"); 425 return SECONDARY_SUPERS_BITMAP_FULL; 426 } 427 i++; 428 } 429 } 430 assert(i == secondaries->length(), "mismatch"); 431 postcond((int)population_count(bitmap) == secondaries->length()); 432 433 return bitmap; 434 } 435 } 436 437 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) { 438 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, ""); 439 440 int dist = 0; 441 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) { 442 Klass* existing = secondaries->at(slot); 443 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch"); 444 if (existing == nullptr) { // no conflict 445 secondaries->at_put(slot, klass); 446 bitmap |= uintx(1) << slot; 447 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, ""); 448 return; 449 } else { 450 // Use Robin Hood hashing to minimize the worst case search. 451 // Also, every permutation of the insertion sequence produces 452 // the same final Robin Hood hash table, provided that a 453 // consistent tie breaker is used. 454 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK; 455 if (existing_dist < dist 456 // This tie breaker ensures that the hash order is maintained. 457 || ((existing_dist == dist) 458 && (uintptr_t(existing) < uintptr_t(klass)))) { 459 Klass* tmp = secondaries->at(slot); 460 secondaries->at_put(slot, klass); 461 klass = tmp; 462 dist = existing_dist; 463 } 464 ++dist; 465 } 466 } 467 } 468 469 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data, 470 GrowableArray<Klass*>* primaries, 471 GrowableArray<Klass*>* secondaries, 472 uintx& bitmap, TRAPS) { 473 int new_length = primaries->length() + secondaries->length(); 474 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL); 475 476 // Combine the two arrays into a metadata object to pack the array. 477 // The primaries are added in the reverse order, then the secondaries. 478 int fill_p = primaries->length(); 479 for (int j = 0; j < fill_p; j++) { 480 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order. 481 } 482 for( int j = 0; j < secondaries->length(); j++ ) { 483 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end. 484 } 485 #ifdef ASSERT 486 // We must not copy any null placeholders left over from bootstrap. 487 for (int j = 0; j < secondary_supers->length(); j++) { 488 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order"); 489 } 490 #endif 491 492 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array 493 return secondary_supers; 494 } 495 496 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) { 497 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed 498 } 499 500 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) { 501 uint8_t hash = k->hash_slot(); 502 if (hash > 0) { 503 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash)); 504 } 505 return 0; 506 } 507 508 509 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) { 510 if (k == nullptr) { 511 set_super(nullptr); 512 _primary_supers[0] = this; 513 assert(super_depth() == 0, "Object must already be initialized properly"); 514 } else if (k != super() || k == vmClasses::Object_klass()) { 515 assert(super() == nullptr || super() == vmClasses::Object_klass(), 516 "initialize this only once to a non-trivial value"); 517 set_super(k); 518 Klass* sup = k; 519 int sup_depth = sup->super_depth(); 520 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit()); 521 if (!can_be_primary_super_slow()) 522 my_depth = primary_super_limit(); 523 for (juint i = 0; i < my_depth; i++) { 524 _primary_supers[i] = sup->_primary_supers[i]; 525 } 526 Klass* *super_check_cell; 527 if (my_depth < primary_super_limit()) { 528 _primary_supers[my_depth] = this; 529 super_check_cell = &_primary_supers[my_depth]; 530 } else { 531 // Overflow of the primary_supers array forces me to be secondary. 532 super_check_cell = &_secondary_super_cache; 533 } 534 set_super_check_offset(u4((address)super_check_cell - (address) this)); 535 536 #ifdef ASSERT 537 { 538 juint j = super_depth(); 539 assert(j == my_depth, "computed accessor gets right answer"); 540 Klass* t = this; 541 while (!t->can_be_primary_super()) { 542 t = t->super(); 543 j = t->super_depth(); 544 } 545 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) { 546 assert(primary_super_of_depth(j1) == nullptr, "super list padding"); 547 } 548 while (t != nullptr) { 549 assert(primary_super_of_depth(j) == t, "super list initialization"); 550 t = t->super(); 551 --j; 552 } 553 assert(j == (juint)-1, "correct depth count"); 554 } 555 #endif 556 } 557 558 if (secondary_supers() == nullptr) { 559 560 // Now compute the list of secondary supertypes. 561 // Secondaries can occasionally be on the super chain, 562 // if the inline "_primary_supers" array overflows. 563 int extras = 0; 564 Klass* p; 565 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) { 566 ++extras; 567 } 568 569 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below 570 571 // Compute the "real" non-extra secondaries. 572 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces); 573 if (secondaries == nullptr) { 574 // secondary_supers set by compute_secondary_supers 575 return; 576 } 577 578 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras); 579 580 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) { 581 int i; // Scan for overflow primaries being duplicates of 2nd'arys 582 583 // This happens frequently for very deeply nested arrays: the 584 // primary superclass chain overflows into the secondary. The 585 // secondary list contains the element_klass's secondaries with 586 // an extra array dimension added. If the element_klass's 587 // secondary list already contains some primary overflows, they 588 // (with the extra level of array-ness) will collide with the 589 // normal primary superclass overflows. 590 for( i = 0; i < secondaries->length(); i++ ) { 591 if( secondaries->at(i) == p ) 592 break; 593 } 594 if( i < secondaries->length() ) 595 continue; // It's a dup, don't put it in 596 primaries->push(p); 597 } 598 // Combine the two arrays into a metadata object to pack the array. 599 uintx bitmap = 0; 600 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK); 601 set_secondary_supers(s2, bitmap); 602 } 603 } 604 605 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots, 606 Array<InstanceKlass*>* transitive_interfaces) { 607 assert(num_extra_slots == 0, "override for complex klasses"); 608 assert(transitive_interfaces == nullptr, "sanity"); 609 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap()); 610 return nullptr; 611 } 612 613 614 // superklass links 615 InstanceKlass* Klass::superklass() const { 616 assert(super() == nullptr || super()->is_instance_klass(), "must be instance klass"); 617 return _super == nullptr ? nullptr : InstanceKlass::cast(_super); 618 } 619 620 // subklass links. Used by the compiler (and vtable initialization) 621 // May be cleaned concurrently, so must use the Compile_lock. 622 // The log parameter is for clean_weak_klass_links to report unlinked classes. 623 Klass* Klass::subklass(bool log) const { 624 // Need load_acquire on the _subklass, because it races with inserts that 625 // publishes freshly initialized data. 626 for (Klass* chain = Atomic::load_acquire(&_subklass); 627 chain != nullptr; 628 // Do not need load_acquire on _next_sibling, because inserts never 629 // create _next_sibling edges to dead data. 630 chain = Atomic::load(&chain->_next_sibling)) 631 { 632 if (chain->is_loader_alive()) { 633 return chain; 634 } else if (log) { 635 if (log_is_enabled(Trace, class, unload)) { 636 ResourceMark rm; 637 log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name()); 638 } 639 } 640 } 641 return nullptr; 642 } 643 644 Klass* Klass::next_sibling(bool log) const { 645 // Do not need load_acquire on _next_sibling, because inserts never 646 // create _next_sibling edges to dead data. 647 for (Klass* chain = Atomic::load(&_next_sibling); 648 chain != nullptr; 649 chain = Atomic::load(&chain->_next_sibling)) { 650 // Only return alive klass, there may be stale klass 651 // in this chain if cleaned concurrently. 652 if (chain->is_loader_alive()) { 653 return chain; 654 } else if (log) { 655 if (log_is_enabled(Trace, class, unload)) { 656 ResourceMark rm; 657 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name()); 658 } 659 } 660 } 661 return nullptr; 662 } 663 664 void Klass::set_subklass(Klass* s) { 665 assert(s != this, "sanity check"); 666 Atomic::release_store(&_subklass, s); 667 } 668 669 void Klass::set_next_sibling(Klass* s) { 670 assert(s != this, "sanity check"); 671 // Does not need release semantics. If used by cleanup, it will link to 672 // already safely published data, and if used by inserts, will be published 673 // safely using cmpxchg. 674 Atomic::store(&_next_sibling, s); 675 } 676 677 void Klass::append_to_sibling_list() { 678 if (Universe::is_fully_initialized()) { 679 assert_locked_or_safepoint(Compile_lock); 680 } 681 DEBUG_ONLY(verify();) 682 // add ourselves to superklass' subklass list 683 InstanceKlass* super = superklass(); 684 if (super == nullptr) return; // special case: class Object 685 assert((!super->is_interface() // interfaces cannot be supers 686 && (super->superklass() == nullptr || !is_interface())), 687 "an interface can only be a subklass of Object"); 688 689 // Make sure there is no stale subklass head 690 super->clean_subklass(); 691 692 for (;;) { 693 Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass); 694 if (prev_first_subklass != nullptr) { 695 // set our sibling to be the superklass' previous first subklass 696 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses"); 697 set_next_sibling(prev_first_subklass); 698 } 699 // Note that the prev_first_subklass is always alive, meaning no sibling_next links 700 // are ever created to not alive klasses. This is an important invariant of the lock-free 701 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list. 702 if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) { 703 return; 704 } 705 } 706 DEBUG_ONLY(verify();) 707 } 708 709 void Klass::clean_subklass() { 710 for (;;) { 711 // Need load_acquire, due to contending with concurrent inserts 712 Klass* subklass = Atomic::load_acquire(&_subklass); 713 if (subklass == nullptr || subklass->is_loader_alive()) { 714 return; 715 } 716 // Try to fix _subklass until it points at something not dead. 717 Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling()); 718 } 719 } 720 721 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) { 722 if (!ClassUnloading || !unloading_occurred) { 723 return; 724 } 725 726 Klass* root = vmClasses::Object_klass(); 727 Stack<Klass*, mtGC> stack; 728 729 stack.push(root); 730 while (!stack.is_empty()) { 731 Klass* current = stack.pop(); 732 733 assert(current->is_loader_alive(), "just checking, this should be live"); 734 735 // Find and set the first alive subklass 736 Klass* sub = current->subklass(true); 737 current->clean_subklass(); 738 if (sub != nullptr) { 739 stack.push(sub); 740 } 741 742 // Find and set the first alive sibling 743 Klass* sibling = current->next_sibling(true); 744 current->set_next_sibling(sibling); 745 if (sibling != nullptr) { 746 stack.push(sibling); 747 } 748 749 // Clean the implementors list and method data. 750 if (clean_alive_klasses && current->is_instance_klass()) { 751 InstanceKlass* ik = InstanceKlass::cast(current); 752 clean_weak_instanceklass_links(ik); 753 } 754 } 755 } 756 757 void Klass::clean_weak_instanceklass_links(InstanceKlass* ik) { 758 ik->clean_weak_instanceklass_links(); 759 // JVMTI RedefineClasses creates previous versions that are not in 760 // the class hierarchy, so process them here. 761 while ((ik = ik->previous_versions()) != nullptr) { 762 ik->clean_weak_instanceklass_links(); 763 } 764 } 765 766 void Klass::metaspace_pointers_do(MetaspaceClosure* it) { 767 if (log_is_enabled(Trace, aot)) { 768 ResourceMark rm; 769 log_trace(aot)("Iter(Klass): %p (%s)", this, external_name()); 770 } 771 772 it->push(&_name); 773 it->push(&_secondary_supers); 774 for (int i = 0; i < _primary_super_limit; i++) { 775 it->push(&_primary_supers[i]); 776 } 777 it->push(&_super); 778 if (!CDSConfig::is_dumping_archive()) { 779 // If dumping archive, these may point to excluded classes. There's no need 780 // to follow these pointers anyway, as they will be set to null in 781 // remove_unshareable_info(). 782 it->push((Klass**)&_subklass); 783 it->push((Klass**)&_next_sibling); 784 it->push(&_next_link); 785 } 786 787 vtableEntry* vt = start_of_vtable(); 788 for (int i=0; i<vtable_length(); i++) { 789 it->push(vt[i].method_addr()); 790 } 791 } 792 793 #if INCLUDE_CDS 794 void Klass::remove_unshareable_info() { 795 assert(CDSConfig::is_dumping_archive(), 796 "only called during CDS dump time"); 797 JFR_ONLY(REMOVE_ID(this);) 798 if (log_is_enabled(Trace, aot, unshareable)) { 799 ResourceMark rm; 800 log_trace(aot, unshareable)("remove: %s", external_name()); 801 } 802 803 // _secondary_super_cache may be updated by an is_subtype_of() call 804 // while ArchiveBuilder is copying metaspace objects. Let's reset it to 805 // null and let it be repopulated at runtime. 806 set_secondary_super_cache(nullptr); 807 808 set_subklass(nullptr); 809 set_next_sibling(nullptr); 810 set_next_link(nullptr); 811 812 // Null out class_loader_data because we don't share that yet. 813 set_class_loader_data(nullptr); 814 set_is_shared(); 815 816 if (CDSConfig::is_dumping_classic_static_archive()) { 817 // "Classic" static archives are required to have deterministic contents. 818 // The elements in _secondary_supers are addresses in the ArchiveBuilder 819 // output buffer, so they should have deterministic values. If we rehash 820 // _secondary_supers, its elements will appear in a deterministic order. 821 // 822 // Note that the bitmap is guaranteed to be deterministic, regardless of the 823 // actual addresses of the elements in _secondary_supers. So rehashing shouldn't 824 // change it. 825 uintx bitmap = hash_secondary_supers(secondary_supers(), true); 826 assert(bitmap == _secondary_supers_bitmap, "bitmap should not be changed due to rehashing"); 827 } 828 } 829 830 void Klass::remove_java_mirror() { 831 assert(CDSConfig::is_dumping_archive(), "sanity"); 832 if (log_is_enabled(Trace, aot, unshareable)) { 833 ResourceMark rm; 834 log_trace(aot, unshareable)("remove java_mirror: %s", external_name()); 835 } 836 837 #if INCLUDE_CDS_JAVA_HEAP 838 _archived_mirror_index = -1; 839 if (CDSConfig::is_dumping_heap()) { 840 Klass* src_k = ArchiveBuilder::current()->get_source_addr(this); 841 oop orig_mirror = src_k->java_mirror(); 842 if (orig_mirror == nullptr) { 843 assert(CDSConfig::is_dumping_final_static_archive(), "sanity"); 844 if (is_instance_klass()) { 845 assert(InstanceKlass::cast(this)->defined_by_other_loaders(), "sanity"); 846 } else { 847 precond(is_objArray_klass()); 848 Klass *k = ObjArrayKlass::cast(this)->bottom_klass(); 849 precond(k->is_instance_klass()); 850 assert(InstanceKlass::cast(k)->defined_by_other_loaders(), "sanity"); 851 } 852 } else { 853 oop scratch_mirror = HeapShared::scratch_java_mirror(orig_mirror); 854 if (scratch_mirror != nullptr) { 855 _archived_mirror_index = HeapShared::append_root(scratch_mirror); 856 } 857 } 858 } 859 #endif 860 861 // Just null out the mirror. The class_loader_data() no longer exists. 862 clear_java_mirror_handle(); 863 } 864 865 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) { 866 assert(is_klass(), "ensure C++ vtable is restored"); 867 assert(is_shared(), "must be set"); 868 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be"); 869 JFR_ONLY(RESTORE_ID(this);) 870 if (log_is_enabled(Trace, aot, unshareable)) { 871 ResourceMark rm(THREAD); 872 oop class_loader = loader_data->class_loader(); 873 log_trace(aot, unshareable)("restore: %s with class loader: %s", external_name(), 874 class_loader != nullptr ? class_loader->klass()->external_name() : "boot"); 875 } 876 877 // If an exception happened during CDS restore, some of these fields may already be 878 // set. We leave the class on the CLD list, even if incomplete so that we don't 879 // modify the CLD list outside a safepoint. 880 if (class_loader_data() == nullptr) { 881 set_class_loader_data(loader_data); 882 883 // Add to class loader list first before creating the mirror 884 // (same order as class file parsing) 885 loader_data->add_class(this); 886 } 887 888 Handle loader(THREAD, loader_data->class_loader()); 889 ModuleEntry* module_entry = nullptr; 890 Klass* k = this; 891 if (k->is_objArray_klass()) { 892 k = ObjArrayKlass::cast(k)->bottom_klass(); 893 } 894 // Obtain klass' module. 895 if (k->is_instance_klass()) { 896 InstanceKlass* ik = (InstanceKlass*) k; 897 module_entry = ik->module(); 898 } else { 899 module_entry = ModuleEntryTable::javabase_moduleEntry(); 900 } 901 // Obtain java.lang.Module, if available 902 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module_oop() : (oop)nullptr)); 903 904 if (this->has_archived_mirror_index()) { 905 ResourceMark rm(THREAD); 906 log_debug(aot, mirror)("%s has raw archived mirror", external_name()); 907 if (ArchiveHeapLoader::is_in_use()) { 908 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle, 909 protection_domain, 910 CHECK); 911 if (present) { 912 return; 913 } 914 } 915 916 // No archived mirror data 917 log_debug(aot, mirror)("No archived mirror data for %s", external_name()); 918 clear_java_mirror_handle(); 919 this->clear_archived_mirror_index(); 920 } 921 922 // Only recreate it if not present. A previous attempt to restore may have 923 // gotten an OOM later but keep the mirror if it was created. 924 if (java_mirror() == nullptr) { 925 ResourceMark rm(THREAD); 926 log_trace(aot, mirror)("Recreate mirror for %s", external_name()); 927 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK); 928 } 929 } 930 #endif // INCLUDE_CDS 931 932 #if INCLUDE_CDS_JAVA_HEAP 933 oop Klass::archived_java_mirror() { 934 assert(has_archived_mirror_index(), "must have archived mirror"); 935 return HeapShared::get_root(_archived_mirror_index); 936 } 937 938 void Klass::clear_archived_mirror_index() { 939 if (_archived_mirror_index >= 0) { 940 HeapShared::clear_root(_archived_mirror_index); 941 } 942 _archived_mirror_index = -1; 943 } 944 #endif // INCLUDE_CDS_JAVA_HEAP 945 946 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) { 947 if (length > max_length) { 948 if (!THREAD->is_in_internal_oome_mark()) { 949 report_java_out_of_memory("Requested array size exceeds VM limit"); 950 JvmtiExport::post_array_size_exhausted(); 951 THROW_OOP(Universe::out_of_memory_error_array_size()); 952 } else { 953 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace()); 954 } 955 } else if (length < 0) { 956 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length)); 957 } 958 } 959 960 // Replace the last '+' char with '/'. 961 static char* convert_hidden_name_to_java(Symbol* name) { 962 size_t name_len = name->utf8_length(); 963 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1); 964 name->as_klass_external_name(result, (int)name_len + 1); 965 for (int index = (int)name_len; index > 0; index--) { 966 if (result[index] == '+') { 967 result[index] = JVM_SIGNATURE_SLASH; 968 break; 969 } 970 } 971 return result; 972 } 973 974 // In product mode, this function doesn't have virtual function calls so 975 // there might be some performance advantage to handling InstanceKlass here. 976 const char* Klass::external_name() const { 977 if (is_instance_klass()) { 978 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this); 979 if (ik->is_hidden()) { 980 char* result = convert_hidden_name_to_java(name()); 981 return result; 982 } 983 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) { 984 char* result = convert_hidden_name_to_java(name()); 985 return result; 986 } 987 if (name() == nullptr) return "<unknown>"; 988 return name()->as_klass_external_name(); 989 } 990 991 const char* Klass::signature_name() const { 992 if (name() == nullptr) return "<unknown>"; 993 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) { 994 size_t name_len = name()->utf8_length(); 995 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1); 996 name()->as_C_string(result, (int)name_len + 1); 997 for (int index = (int)name_len; index > 0; index--) { 998 if (result[index] == '+') { 999 result[index] = JVM_SIGNATURE_DOT; 1000 break; 1001 } 1002 } 1003 return result; 1004 } 1005 return name()->as_C_string(); 1006 } 1007 1008 const char* Klass::external_kind() const { 1009 if (is_interface()) return "interface"; 1010 if (is_abstract()) return "abstract class"; 1011 return "class"; 1012 } 1013 1014 // Unless overridden, jvmti_class_status has no flags set. 1015 jint Klass::jvmti_class_status() const { 1016 return 0; 1017 } 1018 1019 1020 // Printing 1021 1022 void Klass::print_on(outputStream* st) const { 1023 ResourceMark rm; 1024 // print title 1025 st->print("%s", internal_name()); 1026 print_address_on(st); 1027 st->cr(); 1028 } 1029 1030 #define BULLET " - " 1031 1032 // Caller needs ResourceMark 1033 void Klass::oop_print_on(oop obj, outputStream* st) { 1034 // print title 1035 st->print_cr("%s ", internal_name()); 1036 obj->print_address_on(st); 1037 1038 if (WizardMode) { 1039 // print header 1040 obj->mark().print_on(st); 1041 st->cr(); 1042 if (UseCompactObjectHeaders) { 1043 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value()); 1044 st->cr(); 1045 } 1046 } 1047 1048 // print class 1049 st->print(BULLET"klass: "); 1050 obj->klass()->print_value_on(st); 1051 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr(); 1052 st->cr(); 1053 } 1054 1055 void Klass::oop_print_value_on(oop obj, outputStream* st) { 1056 // print title 1057 ResourceMark rm; // Cannot print in debug mode without this 1058 st->print("%s", internal_name()); 1059 obj->print_address_on(st); 1060 } 1061 1062 // Verification 1063 1064 void Klass::verify_on(outputStream* st) { 1065 1066 // This can be expensive, but it is worth checking that this klass is actually 1067 // in the CLD graph but not in production. 1068 #ifdef ASSERT 1069 if (UseCompressedClassPointers && needs_narrow_id()) { 1070 // Stricter checks for both correct alignment and placement 1071 CompressedKlassPointers::check_encodable(this); 1072 } else { 1073 assert(Metaspace::contains((address)this), "Should be"); 1074 } 1075 #endif // ASSERT 1076 1077 guarantee(this->is_klass(),"should be klass"); 1078 1079 if (super() != nullptr) { 1080 guarantee(super()->is_klass(), "should be klass"); 1081 } 1082 if (secondary_super_cache() != nullptr) { 1083 Klass* ko = secondary_super_cache(); 1084 guarantee(ko->is_klass(), "should be klass"); 1085 } 1086 for ( uint i = 0; i < primary_super_limit(); i++ ) { 1087 Klass* ko = _primary_supers[i]; 1088 if (ko != nullptr) { 1089 guarantee(ko->is_klass(), "should be klass"); 1090 } 1091 } 1092 1093 if (java_mirror_no_keepalive() != nullptr) { 1094 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance"); 1095 } 1096 } 1097 1098 void Klass::oop_verify_on(oop obj, outputStream* st) { 1099 guarantee(oopDesc::is_oop(obj), "should be oop"); 1100 guarantee(obj->klass()->is_klass(), "klass field is not a klass"); 1101 } 1102 1103 // Note: this function is called with an address that may or may not be a Klass. 1104 // The point is not to assert it is but to check if it could be. 1105 bool Klass::is_valid(Klass* k) { 1106 if (!is_aligned(k, sizeof(MetaWord))) return false; 1107 if ((size_t)k < os::min_page_size()) return false; 1108 1109 if (!os::is_readable_range(k, k + 1)) return false; 1110 if (!Metaspace::contains(k)) return false; 1111 1112 if (!Symbol::is_valid(k->name())) return false; 1113 return ClassLoaderDataGraph::is_valid(k->class_loader_data()); 1114 } 1115 1116 Method* Klass::method_at_vtable(int index) { 1117 #ifndef PRODUCT 1118 assert(index >= 0, "valid vtable index"); 1119 if (DebugVtables) { 1120 verify_vtable_index(index); 1121 } 1122 #endif 1123 return start_of_vtable()[index].method(); 1124 } 1125 1126 1127 #ifndef PRODUCT 1128 1129 bool Klass::verify_vtable_index(int i) { 1130 int limit = vtable_length()/vtableEntry::size(); 1131 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit); 1132 return true; 1133 } 1134 1135 #endif // PRODUCT 1136 1137 // Caller needs ResourceMark 1138 // joint_in_module_of_loader provides an optimization if 2 classes are in 1139 // the same module to succinctly print out relevant information about their 1140 // module name and class loader's name_and_id for error messages. 1141 // Format: 1142 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2> 1143 // are in module <module-name>[@<version>] 1144 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>] 1145 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const { 1146 assert(module() == class2->module(), "classes do not have the same module"); 1147 const char* class1_name = external_name(); 1148 size_t len = strlen(class1_name) + 1; 1149 1150 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader); 1151 len += strlen(class2_description); 1152 1153 len += strlen(" and "); 1154 1155 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len); 1156 1157 // Just return the FQN if error when allocating string 1158 if (joint_description == nullptr) { 1159 return class1_name; 1160 } 1161 1162 jio_snprintf(joint_description, len, "%s and %s", 1163 class1_name, 1164 class2_description); 1165 1166 return joint_description; 1167 } 1168 1169 // Caller needs ResourceMark 1170 // class_in_module_of_loader provides a standard way to include 1171 // relevant information about a class, such as its module name as 1172 // well as its class loader's name_and_id, in error messages and logging. 1173 // Format: 1174 // <fully-qualified-external-class-name> is in module <module-name>[@<version>] 1175 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>] 1176 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const { 1177 // 1. fully qualified external name of class 1178 const char* klass_name = external_name(); 1179 size_t len = strlen(klass_name) + 1; 1180 1181 // 2. module name + @version 1182 const char* module_name = ""; 1183 const char* version = ""; 1184 bool has_version = false; 1185 bool module_is_named = false; 1186 const char* module_name_phrase = ""; 1187 const Klass* bottom_klass = is_objArray_klass() ? 1188 ObjArrayKlass::cast(this)->bottom_klass() : this; 1189 if (bottom_klass->is_instance_klass()) { 1190 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module(); 1191 if (module->is_named()) { 1192 module_is_named = true; 1193 module_name_phrase = "module "; 1194 module_name = module->name()->as_C_string(); 1195 len += strlen(module_name); 1196 // Use version if exists and is not a jdk module 1197 if (module->should_show_version()) { 1198 has_version = true; 1199 version = module->version()->as_C_string(); 1200 // Include stlen(version) + 1 for the "@" 1201 len += strlen(version) + 1; 1202 } 1203 } else { 1204 module_name = UNNAMED_MODULE; 1205 len += UNNAMED_MODULE_LEN; 1206 } 1207 } else { 1208 // klass is an array of primitives, module is java.base 1209 module_is_named = true; 1210 module_name_phrase = "module "; 1211 module_name = JAVA_BASE_NAME; 1212 len += JAVA_BASE_NAME_LEN; 1213 } 1214 1215 // 3. class loader's name_and_id 1216 ClassLoaderData* cld = class_loader_data(); 1217 assert(cld != nullptr, "class_loader_data should not be null"); 1218 const char* loader_name_and_id = cld->loader_name_and_id(); 1219 len += strlen(loader_name_and_id); 1220 1221 // 4. include parent loader information 1222 const char* parent_loader_phrase = ""; 1223 const char* parent_loader_name_and_id = ""; 1224 if (include_parent_loader && 1225 !cld->is_builtin_class_loader_data()) { 1226 oop parent_loader = java_lang_ClassLoader::parent(class_loader()); 1227 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader); 1228 // The parent loader's ClassLoaderData could be null if it is 1229 // a delegating class loader that has never defined a class. 1230 // In this case the loader's name must be obtained via the parent loader's oop. 1231 if (parent_cld == nullptr) { 1232 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader); 1233 if (cl_name_and_id != nullptr) { 1234 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id); 1235 } 1236 } else { 1237 parent_loader_name_and_id = parent_cld->loader_name_and_id(); 1238 } 1239 parent_loader_phrase = ", parent loader "; 1240 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id); 1241 } 1242 1243 // Start to construct final full class description string 1244 len += ((use_are) ? strlen(" are in ") : strlen(" is in ")); 1245 len += strlen(module_name_phrase) + strlen(" of loader "); 1246 1247 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len); 1248 1249 // Just return the FQN if error when allocating string 1250 if (class_description == nullptr) { 1251 return klass_name; 1252 } 1253 1254 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s", 1255 klass_name, 1256 (use_are) ? "are" : "is", 1257 module_name_phrase, 1258 module_name, 1259 (has_version) ? "@" : "", 1260 (has_version) ? version : "", 1261 loader_name_and_id, 1262 parent_loader_phrase, 1263 parent_loader_name_and_id); 1264 1265 return class_description; 1266 } 1267 1268 class LookupStats : StackObj { 1269 private: 1270 uint _no_of_samples; 1271 uint _worst; 1272 uint _worst_count; 1273 uint _average; 1274 uint _best; 1275 uint _best_count; 1276 public: 1277 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {} 1278 1279 ~LookupStats() { 1280 assert(_best <= _worst || _no_of_samples == 0, "sanity"); 1281 } 1282 1283 void sample(uint value) { 1284 ++_no_of_samples; 1285 _average += value; 1286 1287 if (_worst < value) { 1288 _worst = value; 1289 _worst_count = 1; 1290 } else if (_worst == value) { 1291 ++_worst_count; 1292 } 1293 1294 if (_best > value) { 1295 _best = value; 1296 _best_count = 1; 1297 } else if (_best == value) { 1298 ++_best_count; 1299 } 1300 } 1301 1302 void print_on(outputStream* st) const { 1303 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples); 1304 if (_best_count < _no_of_samples) { 1305 st->print("; average: %4.1f; worst: %2d (%4.1f%%)", 1306 (1.0 * _average) / _no_of_samples, 1307 _worst, (100.0 * _worst_count) / _no_of_samples); 1308 } 1309 } 1310 }; 1311 1312 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) { 1313 int num_of_supers = secondary_supers->length(); 1314 1315 LookupStats s; 1316 for (int i = 0; i < num_of_supers; i++) { 1317 Klass* secondary_super = secondary_supers->at(i); 1318 int home_slot = Klass::compute_home_slot(secondary_super, bitmap); 1319 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK); 1320 s.sample(score); 1321 } 1322 st->print("positive_lookup: "); s.print_on(st); 1323 } 1324 1325 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) { 1326 assert(~bitmap != 0, "no zeroes"); 1327 uintx start = rotate_right(bitmap, slot); 1328 return count_trailing_zeros(~start); 1329 } 1330 1331 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) { 1332 LookupStats s; 1333 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) { 1334 uint score = compute_distance_to_nearest_zero(slot, bitmap); 1335 s.sample(score); 1336 } 1337 st->print("negative_lookup: "); s.print_on(st); 1338 } 1339 1340 void Klass::print_secondary_supers_on(outputStream* st) const { 1341 if (secondary_supers() != nullptr) { 1342 st->print(" - "); st->print("%d elements;", _secondary_supers->length()); 1343 st->print_cr(" bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap); 1344 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY && 1345 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) { 1346 st->print(" - "); print_positive_lookup_stats(secondary_supers(), 1347 _secondary_supers_bitmap, st); st->cr(); 1348 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr(); 1349 } 1350 } else { 1351 st->print("null"); 1352 } 1353 } 1354 1355 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) { 1356 ResourceMark rm; 1357 super->print(); 1358 sub->print(); 1359 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d", 1360 msg, sub->external_name(), super->external_name(), linear_result, table_result); 1361 }