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 bool Klass::can_be_primary_super_slow() const { 332 if (super() == nullptr) 333 return true; 334 else if (super()->super_depth() >= primary_super_limit()-1) 335 return false; 336 else 337 return true; 338 } 339 340 void Klass::set_secondary_supers(Array<Klass*>* secondaries, uintx bitmap) { 341 #ifdef ASSERT 342 if (secondaries != nullptr) { 343 uintx real_bitmap = compute_secondary_supers_bitmap(secondaries); 344 assert(bitmap == real_bitmap, "must be"); 345 assert(secondaries->length() >= (int)population_count(bitmap), "must be"); 346 } 347 #endif 348 _secondary_supers_bitmap = bitmap; 349 _secondary_supers = secondaries; 350 351 if (secondaries != nullptr) { 352 LogMessage(class, load) msg; 353 NonInterleavingLogStream log {LogLevel::Debug, msg}; 354 if (log.is_enabled()) { 355 ResourceMark rm; 356 log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name()); 357 print_secondary_supers_on(&log); 358 } 359 } 360 } 361 362 // Hashed secondary superclasses 363 // 364 // We use a compressed 64-entry hash table with linear probing. We 365 // start by creating a hash table in the usual way, followed by a pass 366 // that removes all the null entries. To indicate which entries would 367 // have been null we use a bitmap that contains a 1 in each position 368 // where an entry is present, 0 otherwise. This bitmap also serves as 369 // a kind of Bloom filter, which in many cases allows us quickly to 370 // eliminate the possibility that something is a member of a set of 371 // secondaries. 372 uintx Klass::hash_secondary_supers(Array<Klass*>* secondaries, bool rewrite) { 373 const int length = secondaries->length(); 374 375 if (length == 0) { 376 return SECONDARY_SUPERS_BITMAP_EMPTY; 377 } 378 379 if (length == 1) { 380 int hash_slot = secondaries->at(0)->hash_slot(); 381 return uintx(1) << hash_slot; 382 } 383 384 // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap) 385 386 // Don't attempt to hash a table that's completely full, because in 387 // the case of an absent interface linear probing would not 388 // terminate. 389 if (length >= SECONDARY_SUPERS_TABLE_SIZE) { 390 return SECONDARY_SUPERS_BITMAP_FULL; 391 } 392 393 { 394 PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time()); 395 396 ResourceMark rm; 397 uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY; 398 auto hashed_secondaries = new GrowableArray<Klass*>(SECONDARY_SUPERS_TABLE_SIZE, 399 SECONDARY_SUPERS_TABLE_SIZE, nullptr); 400 401 for (int j = 0; j < length; j++) { 402 Klass* k = secondaries->at(j); 403 hash_insert(k, hashed_secondaries, bitmap); 404 } 405 406 // Pack the hashed secondaries array by copying it into the 407 // secondaries array, sans nulls, if modification is allowed. 408 // Otherwise, validate the order. 409 int i = 0; 410 for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) { 411 bool has_element = ((bitmap >> slot) & 1) != 0; 412 assert(has_element == (hashed_secondaries->at(slot) != nullptr), ""); 413 if (has_element) { 414 Klass* k = hashed_secondaries->at(slot); 415 if (rewrite) { 416 secondaries->at_put(i, k); 417 } else if (secondaries->at(i) != k) { 418 assert(false, "broken secondary supers hash table"); 419 return SECONDARY_SUPERS_BITMAP_FULL; 420 } 421 i++; 422 } 423 } 424 assert(i == secondaries->length(), "mismatch"); 425 postcond((int)population_count(bitmap) == secondaries->length()); 426 427 return bitmap; 428 } 429 } 430 431 void Klass::hash_insert(Klass* klass, GrowableArray<Klass*>* secondaries, uintx& bitmap) { 432 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, ""); 433 434 int dist = 0; 435 for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) { 436 Klass* existing = secondaries->at(slot); 437 assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch"); 438 if (existing == nullptr) { // no conflict 439 secondaries->at_put(slot, klass); 440 bitmap |= uintx(1) << slot; 441 assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, ""); 442 return; 443 } else { 444 // Use Robin Hood hashing to minimize the worst case search. 445 // Also, every permutation of the insertion sequence produces 446 // the same final Robin Hood hash table, provided that a 447 // consistent tie breaker is used. 448 int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK; 449 if (existing_dist < dist 450 // This tie breaker ensures that the hash order is maintained. 451 || ((existing_dist == dist) 452 && (uintptr_t(existing) < uintptr_t(klass)))) { 453 Klass* tmp = secondaries->at(slot); 454 secondaries->at_put(slot, klass); 455 klass = tmp; 456 dist = existing_dist; 457 } 458 ++dist; 459 } 460 } 461 } 462 463 Array<Klass*>* Klass::pack_secondary_supers(ClassLoaderData* loader_data, 464 GrowableArray<Klass*>* primaries, 465 GrowableArray<Klass*>* secondaries, 466 uintx& bitmap, TRAPS) { 467 int new_length = primaries->length() + secondaries->length(); 468 Array<Klass*>* secondary_supers = MetadataFactory::new_array<Klass*>(loader_data, new_length, CHECK_NULL); 469 470 // Combine the two arrays into a metadata object to pack the array. 471 // The primaries are added in the reverse order, then the secondaries. 472 int fill_p = primaries->length(); 473 for (int j = 0; j < fill_p; j++) { 474 secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order. 475 } 476 for( int j = 0; j < secondaries->length(); j++ ) { 477 secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end. 478 } 479 #ifdef ASSERT 480 // We must not copy any null placeholders left over from bootstrap. 481 for (int j = 0; j < secondary_supers->length(); j++) { 482 assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order"); 483 } 484 #endif 485 486 bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array 487 return secondary_supers; 488 } 489 490 uintx Klass::compute_secondary_supers_bitmap(Array<Klass*>* secondary_supers) { 491 return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed 492 } 493 494 uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) { 495 uint8_t hash = k->hash_slot(); 496 if (hash > 0) { 497 return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash)); 498 } 499 return 0; 500 } 501 502 503 void Klass::initialize_supers(Klass* k, Array<InstanceKlass*>* transitive_interfaces, TRAPS) { 504 if (k == nullptr) { 505 set_super(nullptr); 506 _primary_supers[0] = this; 507 assert(super_depth() == 0, "Object must already be initialized properly"); 508 } else if (k != super() || k == vmClasses::Object_klass()) { 509 assert(super() == nullptr || super() == vmClasses::Object_klass(), 510 "initialize this only once to a non-trivial value"); 511 set_super(k); 512 Klass* sup = k; 513 int sup_depth = sup->super_depth(); 514 juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit()); 515 if (!can_be_primary_super_slow()) 516 my_depth = primary_super_limit(); 517 for (juint i = 0; i < my_depth; i++) { 518 _primary_supers[i] = sup->_primary_supers[i]; 519 } 520 Klass* *super_check_cell; 521 if (my_depth < primary_super_limit()) { 522 _primary_supers[my_depth] = this; 523 super_check_cell = &_primary_supers[my_depth]; 524 } else { 525 // Overflow of the primary_supers array forces me to be secondary. 526 super_check_cell = &_secondary_super_cache; 527 } 528 set_super_check_offset(u4((address)super_check_cell - (address) this)); 529 530 #ifdef ASSERT 531 { 532 juint j = super_depth(); 533 assert(j == my_depth, "computed accessor gets right answer"); 534 Klass* t = this; 535 while (!t->can_be_primary_super()) { 536 t = t->super(); 537 j = t->super_depth(); 538 } 539 for (juint j1 = j+1; j1 < primary_super_limit(); j1++) { 540 assert(primary_super_of_depth(j1) == nullptr, "super list padding"); 541 } 542 while (t != nullptr) { 543 assert(primary_super_of_depth(j) == t, "super list initialization"); 544 t = t->super(); 545 --j; 546 } 547 assert(j == (juint)-1, "correct depth count"); 548 } 549 #endif 550 } 551 552 if (secondary_supers() == nullptr) { 553 554 // Now compute the list of secondary supertypes. 555 // Secondaries can occasionally be on the super chain, 556 // if the inline "_primary_supers" array overflows. 557 int extras = 0; 558 Klass* p; 559 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) { 560 ++extras; 561 } 562 563 ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below 564 565 // Compute the "real" non-extra secondaries. 566 GrowableArray<Klass*>* secondaries = compute_secondary_supers(extras, transitive_interfaces); 567 if (secondaries == nullptr) { 568 // secondary_supers set by compute_secondary_supers 569 return; 570 } 571 572 GrowableArray<Klass*>* primaries = new GrowableArray<Klass*>(extras); 573 574 for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) { 575 int i; // Scan for overflow primaries being duplicates of 2nd'arys 576 577 // This happens frequently for very deeply nested arrays: the 578 // primary superclass chain overflows into the secondary. The 579 // secondary list contains the element_klass's secondaries with 580 // an extra array dimension added. If the element_klass's 581 // secondary list already contains some primary overflows, they 582 // (with the extra level of array-ness) will collide with the 583 // normal primary superclass overflows. 584 for( i = 0; i < secondaries->length(); i++ ) { 585 if( secondaries->at(i) == p ) 586 break; 587 } 588 if( i < secondaries->length() ) 589 continue; // It's a dup, don't put it in 590 primaries->push(p); 591 } 592 // Combine the two arrays into a metadata object to pack the array. 593 uintx bitmap = 0; 594 Array<Klass*>* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK); 595 set_secondary_supers(s2, bitmap); 596 } 597 } 598 599 GrowableArray<Klass*>* Klass::compute_secondary_supers(int num_extra_slots, 600 Array<InstanceKlass*>* transitive_interfaces) { 601 assert(num_extra_slots == 0, "override for complex klasses"); 602 assert(transitive_interfaces == nullptr, "sanity"); 603 set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap()); 604 return nullptr; 605 } 606 607 608 // superklass links 609 InstanceKlass* Klass::superklass() const { 610 assert(super() == nullptr || super()->is_instance_klass(), "must be instance klass"); 611 return _super == nullptr ? nullptr : InstanceKlass::cast(_super); 612 } 613 614 // subklass links. Used by the compiler (and vtable initialization) 615 // May be cleaned concurrently, so must use the Compile_lock. 616 // The log parameter is for clean_weak_klass_links to report unlinked classes. 617 Klass* Klass::subklass(bool log) const { 618 // Need load_acquire on the _subklass, because it races with inserts that 619 // publishes freshly initialized data. 620 for (Klass* chain = Atomic::load_acquire(&_subklass); 621 chain != nullptr; 622 // Do not need load_acquire on _next_sibling, because inserts never 623 // create _next_sibling edges to dead data. 624 chain = Atomic::load(&chain->_next_sibling)) 625 { 626 if (chain->is_loader_alive()) { 627 return chain; 628 } else if (log) { 629 if (log_is_enabled(Trace, class, unload)) { 630 ResourceMark rm; 631 log_trace(class, unload)("unlinking class (subclass): %s", chain->external_name()); 632 } 633 } 634 } 635 return nullptr; 636 } 637 638 Klass* Klass::next_sibling(bool log) const { 639 // Do not need load_acquire on _next_sibling, because inserts never 640 // create _next_sibling edges to dead data. 641 for (Klass* chain = Atomic::load(&_next_sibling); 642 chain != nullptr; 643 chain = Atomic::load(&chain->_next_sibling)) { 644 // Only return alive klass, there may be stale klass 645 // in this chain if cleaned concurrently. 646 if (chain->is_loader_alive()) { 647 return chain; 648 } else if (log) { 649 if (log_is_enabled(Trace, class, unload)) { 650 ResourceMark rm; 651 log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name()); 652 } 653 } 654 } 655 return nullptr; 656 } 657 658 void Klass::set_subklass(Klass* s) { 659 assert(s != this, "sanity check"); 660 Atomic::release_store(&_subklass, s); 661 } 662 663 void Klass::set_next_sibling(Klass* s) { 664 assert(s != this, "sanity check"); 665 // Does not need release semantics. If used by cleanup, it will link to 666 // already safely published data, and if used by inserts, will be published 667 // safely using cmpxchg. 668 Atomic::store(&_next_sibling, s); 669 } 670 671 void Klass::append_to_sibling_list() { 672 if (Universe::is_fully_initialized()) { 673 assert_locked_or_safepoint(Compile_lock); 674 } 675 debug_only(verify();) 676 // add ourselves to superklass' subklass list 677 InstanceKlass* super = superklass(); 678 if (super == nullptr) return; // special case: class Object 679 assert((!super->is_interface() // interfaces cannot be supers 680 && (super->superklass() == nullptr || !is_interface())), 681 "an interface can only be a subklass of Object"); 682 683 // Make sure there is no stale subklass head 684 super->clean_subklass(); 685 686 for (;;) { 687 Klass* prev_first_subklass = Atomic::load_acquire(&_super->_subklass); 688 if (prev_first_subklass != nullptr) { 689 // set our sibling to be the superklass' previous first subklass 690 assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses"); 691 set_next_sibling(prev_first_subklass); 692 } 693 // Note that the prev_first_subklass is always alive, meaning no sibling_next links 694 // are ever created to not alive klasses. This is an important invariant of the lock-free 695 // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list. 696 if (Atomic::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) { 697 return; 698 } 699 } 700 debug_only(verify();) 701 } 702 703 void Klass::clean_subklass() { 704 for (;;) { 705 // Need load_acquire, due to contending with concurrent inserts 706 Klass* subklass = Atomic::load_acquire(&_subklass); 707 if (subklass == nullptr || subklass->is_loader_alive()) { 708 return; 709 } 710 // Try to fix _subklass until it points at something not dead. 711 Atomic::cmpxchg(&_subklass, subklass, subklass->next_sibling()); 712 } 713 } 714 715 void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) { 716 if (!ClassUnloading || !unloading_occurred) { 717 return; 718 } 719 720 Klass* root = vmClasses::Object_klass(); 721 Stack<Klass*, mtGC> stack; 722 723 stack.push(root); 724 while (!stack.is_empty()) { 725 Klass* current = stack.pop(); 726 727 assert(current->is_loader_alive(), "just checking, this should be live"); 728 729 // Find and set the first alive subklass 730 Klass* sub = current->subklass(true); 731 current->clean_subklass(); 732 if (sub != nullptr) { 733 stack.push(sub); 734 } 735 736 // Find and set the first alive sibling 737 Klass* sibling = current->next_sibling(true); 738 current->set_next_sibling(sibling); 739 if (sibling != nullptr) { 740 stack.push(sibling); 741 } 742 743 // Clean the implementors list and method data. 744 if (clean_alive_klasses && current->is_instance_klass()) { 745 InstanceKlass* ik = InstanceKlass::cast(current); 746 ik->clean_weak_instanceklass_links(); 747 748 // 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 } 756 757 void Klass::metaspace_pointers_do(MetaspaceClosure* it) { 758 if (log_is_enabled(Trace, cds)) { 759 ResourceMark rm; 760 log_trace(cds)("Iter(Klass): %p (%s)", this, external_name()); 761 } 762 763 it->push(&_name); 764 it->push(&_secondary_supers); 765 for (int i = 0; i < _primary_super_limit; i++) { 766 it->push(&_primary_supers[i]); 767 } 768 it->push(&_super); 769 if (!CDSConfig::is_dumping_archive()) { 770 // If dumping archive, these may point to excluded classes. There's no need 771 // to follow these pointers anyway, as they will be set to null in 772 // remove_unshareable_info(). 773 it->push((Klass**)&_subklass); 774 it->push((Klass**)&_next_sibling); 775 it->push(&_next_link); 776 } 777 778 vtableEntry* vt = start_of_vtable(); 779 for (int i=0; i<vtable_length(); i++) { 780 it->push(vt[i].method_addr()); 781 } 782 } 783 784 #if INCLUDE_CDS 785 void Klass::remove_unshareable_info() { 786 assert(CDSConfig::is_dumping_archive(), 787 "only called during CDS dump time"); 788 JFR_ONLY(REMOVE_ID(this);) 789 if (log_is_enabled(Trace, cds, unshareable)) { 790 ResourceMark rm; 791 log_trace(cds, unshareable)("remove: %s", external_name()); 792 } 793 794 // _secondary_super_cache may be updated by an is_subtype_of() call 795 // while ArchiveBuilder is copying metaspace objects. Let's reset it to 796 // null and let it be repopulated at runtime. 797 set_secondary_super_cache(nullptr); 798 799 set_subklass(nullptr); 800 set_next_sibling(nullptr); 801 set_next_link(nullptr); 802 803 // Null out class_loader_data because we don't share that yet. 804 set_class_loader_data(nullptr); 805 set_is_shared(); 806 807 // FIXME: validation in Klass::hash_secondary_supers() may fail for shared klasses. 808 // Even though the bitmaps always match, the canonical order of elements in the table 809 // is not guaranteed to stay the same (see tie breaker during Robin Hood hashing in Klass::hash_insert). 810 //assert(compute_secondary_supers_bitmap(secondary_supers()) == _secondary_supers_bitmap, "broken table"); 811 } 812 813 void Klass::remove_java_mirror() { 814 assert(CDSConfig::is_dumping_archive(), "sanity"); 815 if (log_is_enabled(Trace, cds, unshareable)) { 816 ResourceMark rm; 817 log_trace(cds, unshareable)("remove java_mirror: %s", external_name()); 818 } 819 820 #if INCLUDE_CDS_JAVA_HEAP 821 _archived_mirror_index = -1; 822 if (CDSConfig::is_dumping_heap()) { 823 Klass* src_k = ArchiveBuilder::current()->get_source_addr(this); 824 oop orig_mirror = src_k->java_mirror(); 825 oop scratch_mirror = HeapShared::scratch_java_mirror(orig_mirror); 826 if (scratch_mirror != nullptr) { 827 _archived_mirror_index = HeapShared::append_root(scratch_mirror); 828 } 829 } 830 #endif 831 832 // Just null out the mirror. The class_loader_data() no longer exists. 833 clear_java_mirror_handle(); 834 } 835 836 void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) { 837 assert(is_klass(), "ensure C++ vtable is restored"); 838 assert(is_shared(), "must be set"); 839 assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be"); 840 JFR_ONLY(RESTORE_ID(this);) 841 if (log_is_enabled(Trace, cds, unshareable)) { 842 ResourceMark rm(THREAD); 843 oop class_loader = loader_data->class_loader(); 844 log_trace(cds, unshareable)("restore: %s with class loader: %s", external_name(), 845 class_loader != nullptr ? class_loader->klass()->external_name() : "boot"); 846 } 847 848 // If an exception happened during CDS restore, some of these fields may already be 849 // set. We leave the class on the CLD list, even if incomplete so that we don't 850 // modify the CLD list outside a safepoint. 851 if (class_loader_data() == nullptr) { 852 set_class_loader_data(loader_data); 853 854 // Add to class loader list first before creating the mirror 855 // (same order as class file parsing) 856 loader_data->add_class(this); 857 } 858 859 Handle loader(THREAD, loader_data->class_loader()); 860 ModuleEntry* module_entry = nullptr; 861 Klass* k = this; 862 if (k->is_objArray_klass()) { 863 k = ObjArrayKlass::cast(k)->bottom_klass(); 864 } 865 // Obtain klass' module. 866 if (k->is_instance_klass()) { 867 InstanceKlass* ik = (InstanceKlass*) k; 868 module_entry = ik->module(); 869 } else { 870 module_entry = ModuleEntryTable::javabase_moduleEntry(); 871 } 872 // Obtain java.lang.Module, if available 873 Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module() : (oop)nullptr)); 874 875 if (this->has_archived_mirror_index()) { 876 ResourceMark rm(THREAD); 877 log_debug(cds, mirror)("%s has raw archived mirror", external_name()); 878 if (ArchiveHeapLoader::is_in_use()) { 879 bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle, 880 protection_domain, 881 CHECK); 882 if (present) { 883 return; 884 } 885 } 886 887 // No archived mirror data 888 log_debug(cds, mirror)("No archived mirror data for %s", external_name()); 889 clear_java_mirror_handle(); 890 this->clear_archived_mirror_index(); 891 } 892 893 // Only recreate it if not present. A previous attempt to restore may have 894 // gotten an OOM later but keep the mirror if it was created. 895 if (java_mirror() == nullptr) { 896 ResourceMark rm(THREAD); 897 log_trace(cds, mirror)("Recreate mirror for %s", external_name()); 898 java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK); 899 } 900 } 901 #endif // INCLUDE_CDS 902 903 #if INCLUDE_CDS_JAVA_HEAP 904 oop Klass::archived_java_mirror() { 905 assert(has_archived_mirror_index(), "must have archived mirror"); 906 return HeapShared::get_root(_archived_mirror_index); 907 } 908 909 void Klass::clear_archived_mirror_index() { 910 if (_archived_mirror_index >= 0) { 911 HeapShared::clear_root(_archived_mirror_index); 912 } 913 _archived_mirror_index = -1; 914 } 915 #endif // INCLUDE_CDS_JAVA_HEAP 916 917 void Klass::check_array_allocation_length(int length, int max_length, TRAPS) { 918 if (length > max_length) { 919 if (!THREAD->is_in_internal_oome_mark()) { 920 report_java_out_of_memory("Requested array size exceeds VM limit"); 921 JvmtiExport::post_array_size_exhausted(); 922 THROW_OOP(Universe::out_of_memory_error_array_size()); 923 } else { 924 THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace()); 925 } 926 } else if (length < 0) { 927 THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length)); 928 } 929 } 930 931 // Replace the last '+' char with '/'. 932 static char* convert_hidden_name_to_java(Symbol* name) { 933 size_t name_len = name->utf8_length(); 934 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1); 935 name->as_klass_external_name(result, (int)name_len + 1); 936 for (int index = (int)name_len; index > 0; index--) { 937 if (result[index] == '+') { 938 result[index] = JVM_SIGNATURE_SLASH; 939 break; 940 } 941 } 942 return result; 943 } 944 945 // In product mode, this function doesn't have virtual function calls so 946 // there might be some performance advantage to handling InstanceKlass here. 947 const char* Klass::external_name() const { 948 if (is_instance_klass()) { 949 const InstanceKlass* ik = static_cast<const InstanceKlass*>(this); 950 if (ik->is_hidden()) { 951 char* result = convert_hidden_name_to_java(name()); 952 return result; 953 } 954 } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) { 955 char* result = convert_hidden_name_to_java(name()); 956 return result; 957 } 958 if (name() == nullptr) return "<unknown>"; 959 return name()->as_klass_external_name(); 960 } 961 962 const char* Klass::signature_name() const { 963 if (name() == nullptr) return "<unknown>"; 964 if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) { 965 size_t name_len = name()->utf8_length(); 966 char* result = NEW_RESOURCE_ARRAY(char, name_len + 1); 967 name()->as_C_string(result, (int)name_len + 1); 968 for (int index = (int)name_len; index > 0; index--) { 969 if (result[index] == '+') { 970 result[index] = JVM_SIGNATURE_DOT; 971 break; 972 } 973 } 974 return result; 975 } 976 return name()->as_C_string(); 977 } 978 979 const char* Klass::external_kind() const { 980 if (is_interface()) return "interface"; 981 if (is_abstract()) return "abstract class"; 982 return "class"; 983 } 984 985 // Unless overridden, jvmti_class_status has no flags set. 986 jint Klass::jvmti_class_status() const { 987 return 0; 988 } 989 990 991 // Printing 992 993 void Klass::print_on(outputStream* st) const { 994 ResourceMark rm; 995 // print title 996 st->print("%s", internal_name()); 997 print_address_on(st); 998 st->cr(); 999 } 1000 1001 #define BULLET " - " 1002 1003 // Caller needs ResourceMark 1004 void Klass::oop_print_on(oop obj, outputStream* st) { 1005 // print title 1006 st->print_cr("%s ", internal_name()); 1007 obj->print_address_on(st); 1008 1009 if (WizardMode) { 1010 // print header 1011 obj->mark().print_on(st); 1012 st->cr(); 1013 if (UseCompactObjectHeaders) { 1014 st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value()); 1015 st->cr(); 1016 } 1017 } 1018 1019 // print class 1020 st->print(BULLET"klass: "); 1021 obj->klass()->print_value_on(st); 1022 st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr(); 1023 st->cr(); 1024 } 1025 1026 void Klass::oop_print_value_on(oop obj, outputStream* st) { 1027 // print title 1028 ResourceMark rm; // Cannot print in debug mode without this 1029 st->print("%s", internal_name()); 1030 obj->print_address_on(st); 1031 } 1032 1033 // Verification 1034 1035 void Klass::verify_on(outputStream* st) { 1036 1037 // This can be expensive, but it is worth checking that this klass is actually 1038 // in the CLD graph but not in production. 1039 #ifdef ASSERT 1040 if (UseCompressedClassPointers && needs_narrow_id()) { 1041 // Stricter checks for both correct alignment and placement 1042 CompressedKlassPointers::check_encodable(this); 1043 } else { 1044 assert(Metaspace::contains((address)this), "Should be"); 1045 } 1046 #endif // ASSERT 1047 1048 guarantee(this->is_klass(),"should be klass"); 1049 1050 if (super() != nullptr) { 1051 guarantee(super()->is_klass(), "should be klass"); 1052 } 1053 if (secondary_super_cache() != nullptr) { 1054 Klass* ko = secondary_super_cache(); 1055 guarantee(ko->is_klass(), "should be klass"); 1056 } 1057 for ( uint i = 0; i < primary_super_limit(); i++ ) { 1058 Klass* ko = _primary_supers[i]; 1059 if (ko != nullptr) { 1060 guarantee(ko->is_klass(), "should be klass"); 1061 } 1062 } 1063 1064 if (java_mirror_no_keepalive() != nullptr) { 1065 guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance"); 1066 } 1067 } 1068 1069 void Klass::oop_verify_on(oop obj, outputStream* st) { 1070 guarantee(oopDesc::is_oop(obj), "should be oop"); 1071 guarantee(obj->klass()->is_klass(), "klass field is not a klass"); 1072 } 1073 1074 // Note: this function is called with an address that may or may not be a Klass. 1075 // The point is not to assert it is but to check if it could be. 1076 bool Klass::is_valid(Klass* k) { 1077 if (!is_aligned(k, sizeof(MetaWord))) return false; 1078 if ((size_t)k < os::min_page_size()) return false; 1079 1080 if (!os::is_readable_range(k, k + 1)) return false; 1081 if (!Metaspace::contains(k)) return false; 1082 1083 if (!Symbol::is_valid(k->name())) return false; 1084 return ClassLoaderDataGraph::is_valid(k->class_loader_data()); 1085 } 1086 1087 Method* Klass::method_at_vtable(int index) { 1088 #ifndef PRODUCT 1089 assert(index >= 0, "valid vtable index"); 1090 if (DebugVtables) { 1091 verify_vtable_index(index); 1092 } 1093 #endif 1094 return start_of_vtable()[index].method(); 1095 } 1096 1097 1098 #ifndef PRODUCT 1099 1100 bool Klass::verify_vtable_index(int i) { 1101 int limit = vtable_length()/vtableEntry::size(); 1102 assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit); 1103 return true; 1104 } 1105 1106 #endif // PRODUCT 1107 1108 // Caller needs ResourceMark 1109 // joint_in_module_of_loader provides an optimization if 2 classes are in 1110 // the same module to succinctly print out relevant information about their 1111 // module name and class loader's name_and_id for error messages. 1112 // Format: 1113 // <fully-qualified-external-class-name1> and <fully-qualified-external-class-name2> 1114 // are in module <module-name>[@<version>] 1115 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>] 1116 const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const { 1117 assert(module() == class2->module(), "classes do not have the same module"); 1118 const char* class1_name = external_name(); 1119 size_t len = strlen(class1_name) + 1; 1120 1121 const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader); 1122 len += strlen(class2_description); 1123 1124 len += strlen(" and "); 1125 1126 char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len); 1127 1128 // Just return the FQN if error when allocating string 1129 if (joint_description == nullptr) { 1130 return class1_name; 1131 } 1132 1133 jio_snprintf(joint_description, len, "%s and %s", 1134 class1_name, 1135 class2_description); 1136 1137 return joint_description; 1138 } 1139 1140 // Caller needs ResourceMark 1141 // class_in_module_of_loader provides a standard way to include 1142 // relevant information about a class, such as its module name as 1143 // well as its class loader's name_and_id, in error messages and logging. 1144 // Format: 1145 // <fully-qualified-external-class-name> is in module <module-name>[@<version>] 1146 // of loader <loader-name_and_id>[, parent loader <parent-loader-name_and_id>] 1147 const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const { 1148 // 1. fully qualified external name of class 1149 const char* klass_name = external_name(); 1150 size_t len = strlen(klass_name) + 1; 1151 1152 // 2. module name + @version 1153 const char* module_name = ""; 1154 const char* version = ""; 1155 bool has_version = false; 1156 bool module_is_named = false; 1157 const char* module_name_phrase = ""; 1158 const Klass* bottom_klass = is_objArray_klass() ? 1159 ObjArrayKlass::cast(this)->bottom_klass() : this; 1160 if (bottom_klass->is_instance_klass()) { 1161 ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module(); 1162 if (module->is_named()) { 1163 module_is_named = true; 1164 module_name_phrase = "module "; 1165 module_name = module->name()->as_C_string(); 1166 len += strlen(module_name); 1167 // Use version if exists and is not a jdk module 1168 if (module->should_show_version()) { 1169 has_version = true; 1170 version = module->version()->as_C_string(); 1171 // Include stlen(version) + 1 for the "@" 1172 len += strlen(version) + 1; 1173 } 1174 } else { 1175 module_name = UNNAMED_MODULE; 1176 len += UNNAMED_MODULE_LEN; 1177 } 1178 } else { 1179 // klass is an array of primitives, module is java.base 1180 module_is_named = true; 1181 module_name_phrase = "module "; 1182 module_name = JAVA_BASE_NAME; 1183 len += JAVA_BASE_NAME_LEN; 1184 } 1185 1186 // 3. class loader's name_and_id 1187 ClassLoaderData* cld = class_loader_data(); 1188 assert(cld != nullptr, "class_loader_data should not be null"); 1189 const char* loader_name_and_id = cld->loader_name_and_id(); 1190 len += strlen(loader_name_and_id); 1191 1192 // 4. include parent loader information 1193 const char* parent_loader_phrase = ""; 1194 const char* parent_loader_name_and_id = ""; 1195 if (include_parent_loader && 1196 !cld->is_builtin_class_loader_data()) { 1197 oop parent_loader = java_lang_ClassLoader::parent(class_loader()); 1198 ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader); 1199 // The parent loader's ClassLoaderData could be null if it is 1200 // a delegating class loader that has never defined a class. 1201 // In this case the loader's name must be obtained via the parent loader's oop. 1202 if (parent_cld == nullptr) { 1203 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader); 1204 if (cl_name_and_id != nullptr) { 1205 parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id); 1206 } 1207 } else { 1208 parent_loader_name_and_id = parent_cld->loader_name_and_id(); 1209 } 1210 parent_loader_phrase = ", parent loader "; 1211 len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id); 1212 } 1213 1214 // Start to construct final full class description string 1215 len += ((use_are) ? strlen(" are in ") : strlen(" is in ")); 1216 len += strlen(module_name_phrase) + strlen(" of loader "); 1217 1218 char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len); 1219 1220 // Just return the FQN if error when allocating string 1221 if (class_description == nullptr) { 1222 return klass_name; 1223 } 1224 1225 jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s", 1226 klass_name, 1227 (use_are) ? "are" : "is", 1228 module_name_phrase, 1229 module_name, 1230 (has_version) ? "@" : "", 1231 (has_version) ? version : "", 1232 loader_name_and_id, 1233 parent_loader_phrase, 1234 parent_loader_name_and_id); 1235 1236 return class_description; 1237 } 1238 1239 class LookupStats : StackObj { 1240 private: 1241 uint _no_of_samples; 1242 uint _worst; 1243 uint _worst_count; 1244 uint _average; 1245 uint _best; 1246 uint _best_count; 1247 public: 1248 LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {} 1249 1250 ~LookupStats() { 1251 assert(_best <= _worst || _no_of_samples == 0, "sanity"); 1252 } 1253 1254 void sample(uint value) { 1255 ++_no_of_samples; 1256 _average += value; 1257 1258 if (_worst < value) { 1259 _worst = value; 1260 _worst_count = 1; 1261 } else if (_worst == value) { 1262 ++_worst_count; 1263 } 1264 1265 if (_best > value) { 1266 _best = value; 1267 _best_count = 1; 1268 } else if (_best == value) { 1269 ++_best_count; 1270 } 1271 } 1272 1273 void print_on(outputStream* st) const { 1274 st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples); 1275 if (_best_count < _no_of_samples) { 1276 st->print("; average: %4.1f; worst: %2d (%4.1f%%)", 1277 (1.0 * _average) / _no_of_samples, 1278 _worst, (100.0 * _worst_count) / _no_of_samples); 1279 } 1280 } 1281 }; 1282 1283 static void print_positive_lookup_stats(Array<Klass*>* secondary_supers, uintx bitmap, outputStream* st) { 1284 int num_of_supers = secondary_supers->length(); 1285 1286 LookupStats s; 1287 for (int i = 0; i < num_of_supers; i++) { 1288 Klass* secondary_super = secondary_supers->at(i); 1289 int home_slot = Klass::compute_home_slot(secondary_super, bitmap); 1290 uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK); 1291 s.sample(score); 1292 } 1293 st->print("positive_lookup: "); s.print_on(st); 1294 } 1295 1296 static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) { 1297 assert(~bitmap != 0, "no zeroes"); 1298 uintx start = rotate_right(bitmap, slot); 1299 return count_trailing_zeros(~start); 1300 } 1301 1302 static void print_negative_lookup_stats(uintx bitmap, outputStream* st) { 1303 LookupStats s; 1304 for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) { 1305 uint score = compute_distance_to_nearest_zero(slot, bitmap); 1306 s.sample(score); 1307 } 1308 st->print("negative_lookup: "); s.print_on(st); 1309 } 1310 1311 void Klass::print_secondary_supers_on(outputStream* st) const { 1312 if (secondary_supers() != nullptr) { 1313 st->print(" - "); st->print("%d elements;", _secondary_supers->length()); 1314 st->print_cr(" bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap); 1315 if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY && 1316 _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) { 1317 st->print(" - "); print_positive_lookup_stats(secondary_supers(), 1318 _secondary_supers_bitmap, st); st->cr(); 1319 st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr(); 1320 } 1321 } else { 1322 st->print("null"); 1323 } 1324 } 1325 1326 void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) { 1327 ResourceMark rm; 1328 super->print(); 1329 sub->print(); 1330 fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d", 1331 msg, sub->external_name(), super->external_name(), linear_result, table_result); 1332 }