/* * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "cds/cdsConfig.hpp" #include "cds/heapShared.inline.hpp" #include "classfile/classLoader.hpp" #include "classfile/classLoaderData.inline.hpp" #include "classfile/classLoaderDataGraph.inline.hpp" #include "classfile/javaClasses.inline.hpp" #include "classfile/moduleEntry.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/systemDictionaryShared.hpp" #include "classfile/vmClasses.hpp" #include "classfile/vmSymbols.hpp" #include "gc/shared/collectedHeap.inline.hpp" #include "jvm_io.h" #include "logging/log.hpp" #include "memory/metadataFactory.hpp" #include "memory/metaspaceClosure.hpp" #include "memory/oopFactory.hpp" #include "memory/resourceArea.hpp" #include "memory/universe.hpp" #include "oops/compressedKlass.inline.hpp" #include "oops/compressedOops.inline.hpp" #include "oops/instanceKlass.hpp" #include "oops/klass.inline.hpp" #include "oops/objArrayKlass.hpp" #include "oops/oop.inline.hpp" #include "oops/oopHandle.inline.hpp" #include "prims/jvmtiExport.hpp" #include "runtime/atomicAccess.hpp" #include "runtime/handles.inline.hpp" #include "runtime/perfData.hpp" #include "utilities/macros.hpp" #include "utilities/powerOfTwo.hpp" #include "utilities/rotate_bits.hpp" #include "utilities/stack.inline.hpp" #if INCLUDE_JFR #include "jfr/jfr.hpp" #endif void Klass::set_java_mirror(Handle m) { assert(!m.is_null(), "New mirror should never be null."); assert(_java_mirror.is_empty(), "should only be used to initialize mirror"); _java_mirror = class_loader_data()->add_handle(m); } bool Klass::is_cloneable() const { return _misc_flags.is_cloneable_fast() || is_subtype_of(vmClasses::Cloneable_klass()); } uint8_t Klass::compute_hash_slot(Symbol* n) { uint hash_code; // Special cases for the two superclasses of all Array instances. // Code elsewhere assumes, for all instances of ArrayKlass, that // these two interfaces will be in this order. // We ensure there are some empty slots in the hash table between // these two very common interfaces because if they were adjacent // (e.g. Slots 0 and 1), then any other class which hashed to 0 or 1 // would result in a probe length of 3. if (n == vmSymbols::java_lang_Cloneable()) { hash_code = 0; } else if (n == vmSymbols::java_io_Serializable()) { hash_code = SECONDARY_SUPERS_TABLE_SIZE / 2; } else { auto s = (const jbyte*) n->bytes(); hash_code = java_lang_String::hash_code(s, n->utf8_length()); // We use String::hash_code here (rather than e.g. // Symbol::identity_hash()) in order to have a hash code that // does not change from run to run. We want that because the // hash value for a secondary superclass appears in generated // code as a constant. // This constant is magic: see Knuth, "Fibonacci Hashing". constexpr uint multiplier = 2654435769; // (uint)(((u8)1 << 32) / ((1 + sqrt(5)) / 2 )) constexpr uint hash_shift = sizeof(hash_code) * 8 - 6; // The leading bits of the least significant half of the product. hash_code = (hash_code * multiplier) >> hash_shift; if (StressSecondarySupers) { // Generate many hash collisions in order to stress-test the // linear search fallback. hash_code = hash_code % 3; hash_code = hash_code * (SECONDARY_SUPERS_TABLE_SIZE / 3); } } return (hash_code & SECONDARY_SUPERS_TABLE_MASK); } void Klass::set_name(Symbol* n) { _name = n; if (_name != nullptr) { _name->increment_refcount(); } { elapsedTimer selftime; selftime.start(); _hash_slot = compute_hash_slot(n); assert(_hash_slot < SECONDARY_SUPERS_TABLE_SIZE, "required"); selftime.stop(); if (UsePerfData) { ClassLoader::perf_secondary_hash_time()->inc(selftime.ticks()); } } if (CDSConfig::is_dumping_archive() && is_instance_klass()) { SystemDictionaryShared::init_dumptime_info(InstanceKlass::cast(this)); } } bool Klass::is_subclass_of(const Klass* k) const { // Run up the super chain and check if (this == k) return true; Klass* t = const_cast(this)->super(); while (t != nullptr) { if (t == k) return true; t = t->super(); } return false; } void Klass::release_C_heap_structures(bool release_constant_pool) { if (_name != nullptr) _name->decrement_refcount(); } bool Klass::linear_search_secondary_supers(const Klass* k) const { // Scan the array-of-objects for a match // FIXME: We could do something smarter here, maybe a vectorized // comparison or a binary search, but is that worth any added // complexity? int cnt = secondary_supers()->length(); for (int i = 0; i < cnt; i++) { if (secondary_supers()->at(i) == k) { return true; } } return false; } // Given a secondary superklass k, an initial array index, and an // occupancy bitmap rotated such that Bit 1 is the next bit to test, // search for k. bool Klass::fallback_search_secondary_supers(const Klass* k, int index, uintx rotated_bitmap) const { // Once the occupancy bitmap is almost full, it's faster to use a // linear search. if (secondary_supers()->length() > SECONDARY_SUPERS_TABLE_SIZE - 2) { return linear_search_secondary_supers(k); } // This is conventional linear probing, but instead of terminating // when a null entry is found in the table, we maintain a bitmap // in which a 0 indicates missing entries. precond((int)population_count(rotated_bitmap) == secondary_supers()->length()); // The check for secondary_supers()->length() <= SECONDARY_SUPERS_TABLE_SIZE - 2 // at the start of this function guarantees there are 0s in the // bitmap, so this loop eventually terminates. while ((rotated_bitmap & 2) != 0) { if (++index == secondary_supers()->length()) { index = 0; } if (secondary_supers()->at(index) == k) { return true; } rotated_bitmap = rotate_right(rotated_bitmap, 1); } return false; } // Return self, except for abstract classes with exactly 1 // implementor. Then return the 1 concrete implementation. Klass *Klass::up_cast_abstract() { Klass *r = this; while( r->is_abstract() ) { // Receiver is abstract? Klass *s = r->subklass(); // Check for exactly 1 subklass if (s == nullptr || s->next_sibling() != nullptr) // Oops; wrong count; give up return this; // Return 'this' as a no-progress flag r = s; // Loop till find concrete class } return r; // Return the 1 concrete class } // Find LCA in class hierarchy Klass *Klass::LCA( Klass *k2 ) { Klass *k1 = this; while( 1 ) { if( k1->is_subtype_of(k2) ) return k2; if( k2->is_subtype_of(k1) ) return k1; k1 = k1->super(); k2 = k2->super(); } } void Klass::check_valid_for_instantiation(bool throwError, TRAPS) { ResourceMark rm(THREAD); THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError() : vmSymbols::java_lang_InstantiationException(), external_name()); } void Klass::copy_array(arrayOop s, int src_pos, arrayOop d, int dst_pos, int length, TRAPS) { ResourceMark rm(THREAD); assert(s != nullptr, "Throw NPE!"); THROW_MSG(vmSymbols::java_lang_ArrayStoreException(), err_msg("arraycopy: source type %s is not an array", s->klass()->external_name())); } void Klass::initialize(TRAPS) { ShouldNotReachHere(); } void Klass::initialize_preemptable(TRAPS) { ShouldNotReachHere(); } Klass* Klass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const { #ifdef ASSERT tty->print_cr("Error: find_field called on a klass oop." " Likely error: reflection method does not correctly" " wrap return value in a mirror object."); #endif ShouldNotReachHere(); return nullptr; } Method* Klass::uncached_lookup_method(const Symbol* name, const Symbol* signature, OverpassLookupMode overpass_mode, PrivateLookupMode private_mode) const { #ifdef ASSERT tty->print_cr("Error: uncached_lookup_method called on a klass oop." " Likely error: reflection method does not correctly" " wrap return value in a mirror object."); #endif ShouldNotReachHere(); return nullptr; } static markWord make_prototype(const Klass* kls) { markWord prototype = markWord::prototype(); #ifdef _LP64 if (UseCompactObjectHeaders) { // With compact object headers, the narrow Klass ID is part of the mark word. // We therefore seed the mark word with the narrow Klass ID. precond(CompressedKlassPointers::is_encodable(kls)); const narrowKlass nk = CompressedKlassPointers::encode(const_cast(kls)); prototype = prototype.set_narrow_klass(nk); } #endif return prototype; } void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() { return Metaspace::allocate(loader_data, word_size, MetaspaceObj::ClassType, THREAD); } Klass::Klass() : _kind(UnknownKlassKind) { assert(CDSConfig::is_dumping_static_archive() || CDSConfig::is_using_archive(), "only for cds"); } // "Normal" instantiation is preceded by a MetaspaceObj allocation // which zeros out memory - calloc equivalent. // The constructor is also used from CppVtableCloner, // which doesn't zero out the memory before calling the constructor. Klass::Klass(KlassKind kind) : _kind(kind), _prototype_header(make_prototype(this)), _shared_class_path_index(-1) { CDS_ONLY(_aot_class_flags = 0;) CDS_JAVA_HEAP_ONLY(_archived_mirror_index = -1;) _primary_supers[0] = this; set_super_check_offset(in_bytes(primary_supers_offset())); } jint Klass::array_layout_helper(BasicType etype) { assert(etype >= T_BOOLEAN && etype <= T_OBJECT, "valid etype"); // Note that T_ARRAY is not allowed here. int hsize = arrayOopDesc::base_offset_in_bytes(etype); int esize = type2aelembytes(etype); bool isobj = (etype == T_OBJECT); int tag = isobj ? _lh_array_tag_obj_value : _lh_array_tag_type_value; int lh = array_layout_helper(tag, hsize, etype, exact_log2(esize)); assert(lh < (int)_lh_neutral_value, "must look like an array layout"); assert(layout_helper_is_array(lh), "correct kind"); assert(layout_helper_is_objArray(lh) == isobj, "correct kind"); assert(layout_helper_is_typeArray(lh) == !isobj, "correct kind"); assert(layout_helper_header_size(lh) == hsize, "correct decode"); assert(layout_helper_element_type(lh) == etype, "correct decode"); assert(1 << layout_helper_log2_element_size(lh) == esize, "correct decode"); return lh; } int Klass::modifier_flags() const { int mods = java_lang_Class::modifiers(java_mirror()); assert(mods == compute_modifier_flags(), "should be same"); return mods; } bool Klass::can_be_primary_super_slow() const { if (super() == nullptr) return true; else if (super()->super_depth() >= primary_super_limit()-1) return false; else return true; } void Klass::set_secondary_supers(Array* secondaries, uintx bitmap) { #ifdef ASSERT if (secondaries != nullptr) { uintx real_bitmap = compute_secondary_supers_bitmap(secondaries); assert(bitmap == real_bitmap, "must be"); assert(secondaries->length() >= (int)population_count(bitmap), "must be"); } #endif _secondary_supers_bitmap = bitmap; _secondary_supers = secondaries; if (secondaries != nullptr) { LogMessage(class, load) msg; NonInterleavingLogStream log {LogLevel::Debug, msg}; if (log.is_enabled()) { ResourceMark rm; log.print_cr("set_secondary_supers: hash_slot: %d; klass: %s", hash_slot(), external_name()); print_secondary_supers_on(&log); } } } // Hashed secondary superclasses // // We use a compressed 64-entry hash table with linear probing. We // start by creating a hash table in the usual way, followed by a pass // that removes all the null entries. To indicate which entries would // have been null we use a bitmap that contains a 1 in each position // where an entry is present, 0 otherwise. This bitmap also serves as // a kind of Bloom filter, which in many cases allows us quickly to // eliminate the possibility that something is a member of a set of // secondaries. uintx Klass::hash_secondary_supers(Array* secondaries, bool rewrite) { const int length = secondaries->length(); if (length == 0) { return SECONDARY_SUPERS_BITMAP_EMPTY; } if (length == 1) { int hash_slot = secondaries->at(0)->hash_slot(); return uintx(1) << hash_slot; } // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap) // Don't attempt to hash a table that's completely full, because in // the case of an absent interface linear probing would not // terminate. if (length >= SECONDARY_SUPERS_TABLE_SIZE) { return SECONDARY_SUPERS_BITMAP_FULL; } { PerfTraceTime ptt(ClassLoader::perf_secondary_hash_time()); ResourceMark rm; uintx bitmap = SECONDARY_SUPERS_BITMAP_EMPTY; auto hashed_secondaries = new GrowableArray(SECONDARY_SUPERS_TABLE_SIZE, SECONDARY_SUPERS_TABLE_SIZE, nullptr); for (int j = 0; j < length; j++) { Klass* k = secondaries->at(j); hash_insert(k, hashed_secondaries, bitmap); } // Pack the hashed secondaries array by copying it into the // secondaries array, sans nulls, if modification is allowed. // Otherwise, validate the order. int i = 0; for (int slot = 0; slot < SECONDARY_SUPERS_TABLE_SIZE; slot++) { bool has_element = ((bitmap >> slot) & 1) != 0; assert(has_element == (hashed_secondaries->at(slot) != nullptr), ""); if (has_element) { Klass* k = hashed_secondaries->at(slot); if (rewrite) { secondaries->at_put(i, k); } else if (secondaries->at(i) != k) { assert(false, "broken secondary supers hash table"); return SECONDARY_SUPERS_BITMAP_FULL; } i++; } } assert(i == secondaries->length(), "mismatch"); postcond((int)population_count(bitmap) == secondaries->length()); return bitmap; } } void Klass::hash_insert(Klass* klass, GrowableArray* secondaries, uintx& bitmap) { assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, ""); int dist = 0; for (int slot = klass->hash_slot(); true; slot = (slot + 1) & SECONDARY_SUPERS_TABLE_MASK) { Klass* existing = secondaries->at(slot); assert(((bitmap >> slot) & 1) == (existing != nullptr), "mismatch"); if (existing == nullptr) { // no conflict secondaries->at_put(slot, klass); bitmap |= uintx(1) << slot; assert(bitmap != SECONDARY_SUPERS_BITMAP_FULL, ""); return; } else { // Use Robin Hood hashing to minimize the worst case search. // Also, every permutation of the insertion sequence produces // the same final Robin Hood hash table, provided that a // consistent tie breaker is used. int existing_dist = (slot - existing->hash_slot()) & SECONDARY_SUPERS_TABLE_MASK; if (existing_dist < dist // This tie breaker ensures that the hash order is maintained. || ((existing_dist == dist) && (uintptr_t(existing) < uintptr_t(klass)))) { Klass* tmp = secondaries->at(slot); secondaries->at_put(slot, klass); klass = tmp; dist = existing_dist; } ++dist; } } } Array* Klass::pack_secondary_supers(ClassLoaderData* loader_data, GrowableArray* primaries, GrowableArray* secondaries, uintx& bitmap, TRAPS) { int new_length = primaries->length() + secondaries->length(); Array* secondary_supers = MetadataFactory::new_array(loader_data, new_length, CHECK_NULL); // Combine the two arrays into a metadata object to pack the array. // The primaries are added in the reverse order, then the secondaries. int fill_p = primaries->length(); for (int j = 0; j < fill_p; j++) { secondary_supers->at_put(j, primaries->pop()); // add primaries in reverse order. } for( int j = 0; j < secondaries->length(); j++ ) { secondary_supers->at_put(j+fill_p, secondaries->at(j)); // add secondaries on the end. } #ifdef ASSERT // We must not copy any null placeholders left over from bootstrap. for (int j = 0; j < secondary_supers->length(); j++) { assert(secondary_supers->at(j) != nullptr, "correct bootstrapping order"); } #endif bitmap = hash_secondary_supers(secondary_supers, /*rewrite=*/true); // rewrites freshly allocated array return secondary_supers; } uintx Klass::compute_secondary_supers_bitmap(Array* secondary_supers) { return hash_secondary_supers(secondary_supers, /*rewrite=*/false); // no rewrites allowed } uint8_t Klass::compute_home_slot(Klass* k, uintx bitmap) { uint8_t hash = k->hash_slot(); if (hash > 0) { return population_count(bitmap << (SECONDARY_SUPERS_TABLE_SIZE - hash)); } return 0; } void Klass::initialize_supers(Klass* k, Array* transitive_interfaces, TRAPS) { if (k == nullptr) { set_super(nullptr); _primary_supers[0] = this; assert(super_depth() == 0, "Object must already be initialized properly"); } else if (k != super() || k == vmClasses::Object_klass()) { assert(super() == nullptr || super() == vmClasses::Object_klass(), "initialize this only once to a non-trivial value"); set_super(k); Klass* sup = k; int sup_depth = sup->super_depth(); juint my_depth = MIN2(sup_depth + 1, (int)primary_super_limit()); if (!can_be_primary_super_slow()) my_depth = primary_super_limit(); for (juint i = 0; i < my_depth; i++) { _primary_supers[i] = sup->_primary_supers[i]; } Klass* *super_check_cell; if (my_depth < primary_super_limit()) { _primary_supers[my_depth] = this; super_check_cell = &_primary_supers[my_depth]; } else { // Overflow of the primary_supers array forces me to be secondary. super_check_cell = &_secondary_super_cache; } set_super_check_offset(u4((address)super_check_cell - (address) this)); #ifdef ASSERT { juint j = super_depth(); assert(j == my_depth, "computed accessor gets right answer"); Klass* t = this; while (!t->can_be_primary_super()) { t = t->super(); j = t->super_depth(); } for (juint j1 = j+1; j1 < primary_super_limit(); j1++) { assert(primary_super_of_depth(j1) == nullptr, "super list padding"); } while (t != nullptr) { assert(primary_super_of_depth(j) == t, "super list initialization"); t = t->super(); --j; } assert(j == (juint)-1, "correct depth count"); } #endif } if (secondary_supers() == nullptr) { // Now compute the list of secondary supertypes. // Secondaries can occasionally be on the super chain, // if the inline "_primary_supers" array overflows. int extras = 0; Klass* p; for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) { ++extras; } ResourceMark rm(THREAD); // need to reclaim GrowableArrays allocated below // Compute the "real" non-extra secondaries. GrowableArray* secondaries = compute_secondary_supers(extras, transitive_interfaces); if (secondaries == nullptr) { // secondary_supers set by compute_secondary_supers return; } GrowableArray* primaries = new GrowableArray(extras); for (p = super(); !(p == nullptr || p->can_be_primary_super()); p = p->super()) { int i; // Scan for overflow primaries being duplicates of 2nd'arys // This happens frequently for very deeply nested arrays: the // primary superclass chain overflows into the secondary. The // secondary list contains the element_klass's secondaries with // an extra array dimension added. If the element_klass's // secondary list already contains some primary overflows, they // (with the extra level of array-ness) will collide with the // normal primary superclass overflows. for( i = 0; i < secondaries->length(); i++ ) { if( secondaries->at(i) == p ) break; } if( i < secondaries->length() ) continue; // It's a dup, don't put it in primaries->push(p); } // Combine the two arrays into a metadata object to pack the array. uintx bitmap = 0; Array* s2 = pack_secondary_supers(class_loader_data(), primaries, secondaries, bitmap, CHECK); set_secondary_supers(s2, bitmap); } } GrowableArray* Klass::compute_secondary_supers(int num_extra_slots, Array* transitive_interfaces) { assert(num_extra_slots == 0, "override for complex klasses"); assert(transitive_interfaces == nullptr, "sanity"); set_secondary_supers(Universe::the_empty_klass_array(), Universe::the_empty_klass_bitmap()); return nullptr; } // subklass links. Used by the compiler (and vtable initialization) // May be cleaned concurrently, so must use the Compile_lock. Klass* Klass::subklass() const { // Need load_acquire on the _subklass, because it races with inserts that // publishes freshly initialized data. for (Klass* chain = AtomicAccess::load_acquire(&_subklass); chain != nullptr; // Do not need load_acquire on _next_sibling, because inserts never // create _next_sibling edges to dead data. chain = AtomicAccess::load(&chain->_next_sibling)) { if (chain->is_loader_alive()) { return chain; } } return nullptr; } Klass* Klass::next_sibling(bool log) const { // Do not need load_acquire on _next_sibling, because inserts never // create _next_sibling edges to dead data. for (Klass* chain = AtomicAccess::load(&_next_sibling); chain != nullptr; chain = AtomicAccess::load(&chain->_next_sibling)) { // Only return alive klass, there may be stale klass // in this chain if cleaned concurrently. if (chain->is_loader_alive()) { return chain; } else if (log) { if (log_is_enabled(Trace, class, unload)) { ResourceMark rm; log_trace(class, unload)("unlinking class (sibling): %s", chain->external_name()); } } } return nullptr; } void Klass::set_subklass(Klass* s) { assert(s != this, "sanity check"); AtomicAccess::release_store(&_subklass, s); } void Klass::set_next_sibling(Klass* s) { assert(s != this, "sanity check"); // Does not need release semantics. If used by cleanup, it will link to // already safely published data, and if used by inserts, will be published // safely using cmpxchg. AtomicAccess::store(&_next_sibling, s); } void Klass::append_to_sibling_list() { if (Universe::is_fully_initialized()) { assert_locked_or_safepoint(Compile_lock); } DEBUG_ONLY(verify();) // add ourselves to super' subklass list InstanceKlass* super = java_super(); if (super == nullptr) return; // special case: class Object assert((!super->is_interface() // interfaces cannot be supers && (super->java_super() == nullptr || !is_interface())), "an interface can only be a subklass of Object"); // Make sure there is no stale subklass head super->clean_subklass(); for (;;) { Klass* prev_first_subklass = AtomicAccess::load_acquire(&_super->_subklass); if (prev_first_subklass != nullptr) { // set our sibling to be the super' previous first subklass assert(prev_first_subklass->is_loader_alive(), "May not attach not alive klasses"); set_next_sibling(prev_first_subklass); } // Note that the prev_first_subklass is always alive, meaning no sibling_next links // are ever created to not alive klasses. This is an important invariant of the lock-free // cleaning protocol, that allows us to safely unlink dead klasses from the sibling list. if (AtomicAccess::cmpxchg(&super->_subklass, prev_first_subklass, this) == prev_first_subklass) { return; } } DEBUG_ONLY(verify();) } // The log parameter is for clean_weak_klass_links to report unlinked classes. Klass* Klass::clean_subklass(bool log) { for (;;) { // Need load_acquire, due to contending with concurrent inserts Klass* subklass = AtomicAccess::load_acquire(&_subklass); if (subklass == nullptr || subklass->is_loader_alive()) { return subklass; } if (log && log_is_enabled(Trace, class, unload)) { ResourceMark rm; log_trace(class, unload)("unlinking class (subclass): %s", subklass->external_name()); } // Try to fix _subklass until it points at something not dead. AtomicAccess::cmpxchg(&_subklass, subklass, subklass->next_sibling(log)); } } void Klass::clean_weak_klass_links(bool unloading_occurred, bool clean_alive_klasses) { if (!ClassUnloading || !unloading_occurred) { return; } Klass* root = vmClasses::Object_klass(); Stack stack; stack.push(root); while (!stack.is_empty()) { Klass* current = stack.pop(); assert(current->is_loader_alive(), "just checking, this should be live"); // Find and set the first alive subklass Klass* sub = current->clean_subklass(true); if (sub != nullptr) { stack.push(sub); } // Find and set the first alive sibling Klass* sibling = current->next_sibling(true); current->set_next_sibling(sibling); if (sibling != nullptr) { stack.push(sibling); } // Clean the implementors list and method data. if (clean_alive_klasses && current->is_instance_klass()) { InstanceKlass* ik = InstanceKlass::cast(current); clean_weak_instanceklass_links(ik); } } } void Klass::clean_weak_instanceklass_links(InstanceKlass* ik) { ik->clean_weak_instanceklass_links(); // JVMTI RedefineClasses creates previous versions that are not in // the class hierarchy, so process them here. while ((ik = ik->previous_versions()) != nullptr) { ik->clean_weak_instanceklass_links(); } } void Klass::metaspace_pointers_do(MetaspaceClosure* it) { if (log_is_enabled(Trace, aot)) { ResourceMark rm; log_trace(aot)("Iter(Klass): %p (%s)", this, external_name()); } it->push(&_name); it->push(&_secondary_supers); for (int i = 0; i < _primary_super_limit; i++) { it->push(&_primary_supers[i]); } it->push(&_super); if (!CDSConfig::is_dumping_archive()) { // If dumping archive, these may point to excluded classes. There's no need // to follow these pointers anyway, as they will be set to null in // remove_unshareable_info(). it->push((Klass**)&_subklass); it->push((Klass**)&_next_sibling); it->push(&_next_link); } vtableEntry* vt = start_of_vtable(); for (int i=0; ipush(vt[i].method_addr()); } } #if INCLUDE_CDS void Klass::remove_unshareable_info() { assert(CDSConfig::is_dumping_archive(), "only called during CDS dump time"); JFR_ONLY(REMOVE_ID(this);) if (log_is_enabled(Trace, aot, unshareable)) { ResourceMark rm; log_trace(aot, unshareable)("remove: %s", external_name()); } // _secondary_super_cache may be updated by an is_subtype_of() call // while ArchiveBuilder is copying metaspace objects. Let's reset it to // null and let it be repopulated at runtime. set_secondary_super_cache(nullptr); set_subklass(nullptr); set_next_sibling(nullptr); set_next_link(nullptr); // Null out class_loader_data because we don't share that yet. set_class_loader_data(nullptr); set_in_aot_cache(); if (CDSConfig::is_dumping_classic_static_archive()) { // "Classic" static archives are required to have deterministic contents. // The elements in _secondary_supers are addresses in the ArchiveBuilder // output buffer, so they should have deterministic values. If we rehash // _secondary_supers, its elements will appear in a deterministic order. // // Note that the bitmap is guaranteed to be deterministic, regardless of the // actual addresses of the elements in _secondary_supers. So rehashing shouldn't // change it. uintx bitmap = hash_secondary_supers(secondary_supers(), true); assert(bitmap == _secondary_supers_bitmap, "bitmap should not be changed due to rehashing"); } } void Klass::remove_java_mirror() { assert(CDSConfig::is_dumping_archive(), "sanity"); if (log_is_enabled(Trace, aot, unshareable)) { ResourceMark rm; log_trace(aot, unshareable)("remove java_mirror: %s", external_name()); } #if INCLUDE_CDS_JAVA_HEAP _archived_mirror_index = -1; if (CDSConfig::is_dumping_heap()) { Klass* src_k = ArchiveBuilder::current()->get_source_addr(this); oop orig_mirror = src_k->java_mirror(); if (orig_mirror == nullptr) { assert(CDSConfig::is_dumping_final_static_archive(), "sanity"); if (is_instance_klass()) { assert(InstanceKlass::cast(this)->defined_by_other_loaders(), "sanity"); } else { precond(is_objArray_klass()); Klass *k = ObjArrayKlass::cast(this)->bottom_klass(); precond(k->is_instance_klass()); assert(InstanceKlass::cast(k)->defined_by_other_loaders(), "sanity"); } } else { oop scratch_mirror = HeapShared::scratch_java_mirror(orig_mirror); if (scratch_mirror != nullptr) { _archived_mirror_index = HeapShared::append_root(scratch_mirror); } } } #endif // Just null out the mirror. The class_loader_data() no longer exists. clear_java_mirror_handle(); } void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) { assert(is_klass(), "ensure C++ vtable is restored"); assert(in_aot_cache(), "must be set"); assert(secondary_supers()->length() >= (int)population_count(_secondary_supers_bitmap), "must be"); if (log_is_enabled(Trace, aot, unshareable)) { ResourceMark rm(THREAD); oop class_loader = loader_data->class_loader(); log_trace(aot, unshareable)("restore: %s with class loader: %s", external_name(), class_loader != nullptr ? class_loader->klass()->external_name() : "boot"); } // If an exception happened during CDS restore, some of these fields may already be // set. We leave the class on the CLD list, even if incomplete so that we don't // modify the CLD list outside a safepoint. if (class_loader_data() == nullptr) { set_class_loader_data(loader_data); } // Add to class loader list first before creating the mirror // (same order as class file parsing) loader_data->add_class(this); JFR_ONLY(Jfr::on_restoration(this, THREAD);) Handle loader(THREAD, loader_data->class_loader()); ModuleEntry* module_entry = nullptr; Klass* k = this; if (k->is_objArray_klass()) { k = ObjArrayKlass::cast(k)->bottom_klass(); } // Obtain klass' module. if (k->is_instance_klass()) { InstanceKlass* ik = (InstanceKlass*) k; module_entry = ik->module(); } else { module_entry = ModuleEntryTable::javabase_moduleEntry(); } // Obtain java.lang.Module, if available Handle module_handle(THREAD, ((module_entry != nullptr) ? module_entry->module_oop() : (oop)nullptr)); if (this->has_archived_mirror_index()) { ResourceMark rm(THREAD); log_debug(aot, mirror)("%s has raw archived mirror", external_name()); if (HeapShared::is_archived_heap_in_use()) { bool present = java_lang_Class::restore_archived_mirror(this, loader, module_handle, protection_domain, CHECK); if (present) { return; } } // No archived mirror data log_debug(aot, mirror)("No archived mirror data for %s", external_name()); clear_java_mirror_handle(); this->clear_archived_mirror_index(); } // Only recreate it if not present. A previous attempt to restore may have // gotten an OOM later but keep the mirror if it was created. if (java_mirror() == nullptr) { ResourceMark rm(THREAD); log_trace(aot, mirror)("Recreate mirror for %s", external_name()); java_lang_Class::create_mirror(this, loader, module_handle, protection_domain, Handle(), CHECK); } } #endif // INCLUDE_CDS #if INCLUDE_CDS_JAVA_HEAP oop Klass::archived_java_mirror() { assert(has_archived_mirror_index(), "must have archived mirror"); return HeapShared::get_root(_archived_mirror_index); } void Klass::clear_archived_mirror_index() { if (_archived_mirror_index >= 0) { HeapShared::clear_root(_archived_mirror_index); } _archived_mirror_index = -1; } #endif // INCLUDE_CDS_JAVA_HEAP void Klass::check_array_allocation_length(int length, int max_length, TRAPS) { if (length > max_length) { if (!THREAD->is_in_internal_oome_mark()) { report_java_out_of_memory("Requested array size exceeds VM limit"); JvmtiExport::post_array_size_exhausted(); THROW_OOP(Universe::out_of_memory_error_array_size()); } else { THROW_OOP(Universe::out_of_memory_error_java_heap_without_backtrace()); } } else if (length < 0) { THROW_MSG(vmSymbols::java_lang_NegativeArraySizeException(), err_msg("%d", length)); } } // Replace the last '+' char with '/'. static char* convert_hidden_name_to_java(Symbol* name) { size_t name_len = name->utf8_length(); char* result = NEW_RESOURCE_ARRAY(char, name_len + 1); name->as_klass_external_name(result, (int)name_len + 1); for (int index = (int)name_len; index > 0; index--) { if (result[index] == '+') { result[index] = JVM_SIGNATURE_SLASH; break; } } return result; } // In product mode, this function doesn't have virtual function calls so // there might be some performance advantage to handling InstanceKlass here. const char* Klass::external_name() const { if (is_instance_klass()) { const InstanceKlass* ik = static_cast(this); if (ik->is_hidden()) { char* result = convert_hidden_name_to_java(name()); return result; } } else if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) { char* result = convert_hidden_name_to_java(name()); return result; } if (name() == nullptr) return ""; return name()->as_klass_external_name(); } const char* Klass::signature_name() const { if (name() == nullptr) return ""; if (is_objArray_klass() && ObjArrayKlass::cast(this)->bottom_klass()->is_hidden()) { size_t name_len = name()->utf8_length(); char* result = NEW_RESOURCE_ARRAY(char, name_len + 1); name()->as_C_string(result, (int)name_len + 1); for (int index = (int)name_len; index > 0; index--) { if (result[index] == '+') { result[index] = JVM_SIGNATURE_DOT; break; } } return result; } return name()->as_C_string(); } const char* Klass::external_kind() const { if (is_interface()) return "interface"; if (is_abstract()) return "abstract class"; return "class"; } // Unless overridden, jvmti_class_status has no flags set. jint Klass::jvmti_class_status() const { return 0; } // Printing void Klass::print_on(outputStream* st) const { ResourceMark rm; // print title st->print("%s", internal_name()); print_address_on(st); st->cr(); } #define BULLET " - " // Caller needs ResourceMark void Klass::oop_print_on(oop obj, outputStream* st) { // print title st->print_cr("%s ", internal_name()); obj->print_address_on(st); if (WizardMode) { // print header obj->mark().print_on(st); st->cr(); if (UseCompactObjectHeaders) { st->print(BULLET"prototype_header: " INTPTR_FORMAT, _prototype_header.value()); st->cr(); } } // print class st->print(BULLET"klass: "); obj->klass()->print_value_on(st); st->print(BULLET"flags: "); _misc_flags.print_on(st); st->cr(); st->cr(); } void Klass::oop_print_value_on(oop obj, outputStream* st) { // print title ResourceMark rm; // Cannot print in debug mode without this st->print("%s", internal_name()); obj->print_address_on(st); } // Verification void Klass::verify_on(outputStream* st) { // This can be expensive, but it is worth checking that this klass is actually // in the CLD graph but not in production. // Stricter checks for both correct alignment and placement DEBUG_ONLY(CompressedKlassPointers::check_encodable(this)); guarantee(this->is_klass(),"should be klass"); if (super() != nullptr) { guarantee(super()->is_klass(), "should be klass"); } if (secondary_super_cache() != nullptr) { Klass* ko = secondary_super_cache(); guarantee(ko->is_klass(), "should be klass"); } for ( uint i = 0; i < primary_super_limit(); i++ ) { Klass* ko = _primary_supers[i]; if (ko != nullptr) { guarantee(ko->is_klass(), "should be klass"); } } if (java_mirror_no_keepalive() != nullptr) { guarantee(java_lang_Class::is_instance(java_mirror_no_keepalive()), "should be instance"); } } void Klass::oop_verify_on(oop obj, outputStream* st) { guarantee(oopDesc::is_oop(obj), "should be oop"); guarantee(obj->klass()->is_klass(), "klass field is not a klass"); } // Note: this function is called with an address that may or may not be a Klass. // The point is not to assert it is but to check if it could be. bool Klass::is_valid(Klass* k) { if (!is_aligned(k, sizeof(MetaWord))) return false; if ((size_t)k < os::min_page_size()) return false; if (!os::is_readable_range(k, k + 1)) return false; if (!Metaspace::contains(k)) return false; if (!Symbol::is_valid(k->name())) return false; return ClassLoaderDataGraph::is_valid(k->class_loader_data()); } Method* Klass::method_at_vtable(int index) { #ifndef PRODUCT assert(index >= 0, "valid vtable index"); if (DebugVtables) { verify_vtable_index(index); } #endif return start_of_vtable()[index].method(); } #ifndef PRODUCT bool Klass::verify_vtable_index(int i) { int limit = vtable_length()/vtableEntry::size(); assert(i >= 0 && i < limit, "index %d out of bounds %d", i, limit); return true; } #endif // PRODUCT // Caller needs ResourceMark // joint_in_module_of_loader provides an optimization if 2 classes are in // the same module to succinctly print out relevant information about their // module name and class loader's name_and_id for error messages. // Format: // and // are in module [@] // of loader [, parent loader ] const char* Klass::joint_in_module_of_loader(const Klass* class2, bool include_parent_loader) const { assert(module() == class2->module(), "classes do not have the same module"); const char* class1_name = external_name(); size_t len = strlen(class1_name) + 1; const char* class2_description = class2->class_in_module_of_loader(true, include_parent_loader); len += strlen(class2_description); len += strlen(" and "); char* joint_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len); // Just return the FQN if error when allocating string if (joint_description == nullptr) { return class1_name; } jio_snprintf(joint_description, len, "%s and %s", class1_name, class2_description); return joint_description; } // Caller needs ResourceMark // class_in_module_of_loader provides a standard way to include // relevant information about a class, such as its module name as // well as its class loader's name_and_id, in error messages and logging. // Format: // is in module [@] // of loader [, parent loader ] const char* Klass::class_in_module_of_loader(bool use_are, bool include_parent_loader) const { // 1. fully qualified external name of class const char* klass_name = external_name(); size_t len = strlen(klass_name) + 1; // 2. module name + @version const char* module_name = ""; const char* version = ""; bool has_version = false; bool module_is_named = false; const char* module_name_phrase = ""; const Klass* bottom_klass = is_objArray_klass() ? ObjArrayKlass::cast(this)->bottom_klass() : this; if (bottom_klass->is_instance_klass()) { ModuleEntry* module = InstanceKlass::cast(bottom_klass)->module(); if (module->is_named()) { module_is_named = true; module_name_phrase = "module "; module_name = module->name()->as_C_string(); len += strlen(module_name); // Use version if exists and is not a jdk module if (module->should_show_version()) { has_version = true; version = module->version()->as_C_string(); // Include stlen(version) + 1 for the "@" len += strlen(version) + 1; } } else { module_name = UNNAMED_MODULE; len += UNNAMED_MODULE_LEN; } } else { // klass is an array of primitives, module is java.base module_is_named = true; module_name_phrase = "module "; module_name = JAVA_BASE_NAME; len += JAVA_BASE_NAME_LEN; } // 3. class loader's name_and_id ClassLoaderData* cld = class_loader_data(); assert(cld != nullptr, "class_loader_data should not be null"); const char* loader_name_and_id = cld->loader_name_and_id(); len += strlen(loader_name_and_id); // 4. include parent loader information const char* parent_loader_phrase = ""; const char* parent_loader_name_and_id = ""; if (include_parent_loader && !cld->is_builtin_class_loader_data()) { oop parent_loader = java_lang_ClassLoader::parent(class_loader()); ClassLoaderData *parent_cld = ClassLoaderData::class_loader_data_or_null(parent_loader); // The parent loader's ClassLoaderData could be null if it is // a delegating class loader that has never defined a class. // In this case the loader's name must be obtained via the parent loader's oop. if (parent_cld == nullptr) { oop cl_name_and_id = java_lang_ClassLoader::nameAndId(parent_loader); if (cl_name_and_id != nullptr) { parent_loader_name_and_id = java_lang_String::as_utf8_string(cl_name_and_id); } } else { parent_loader_name_and_id = parent_cld->loader_name_and_id(); } parent_loader_phrase = ", parent loader "; len += strlen(parent_loader_phrase) + strlen(parent_loader_name_and_id); } // Start to construct final full class description string len += ((use_are) ? strlen(" are in ") : strlen(" is in ")); len += strlen(module_name_phrase) + strlen(" of loader "); char* class_description = NEW_RESOURCE_ARRAY_RETURN_NULL(char, len); // Just return the FQN if error when allocating string if (class_description == nullptr) { return klass_name; } jio_snprintf(class_description, len, "%s %s in %s%s%s%s of loader %s%s%s", klass_name, (use_are) ? "are" : "is", module_name_phrase, module_name, (has_version) ? "@" : "", (has_version) ? version : "", loader_name_and_id, parent_loader_phrase, parent_loader_name_and_id); return class_description; } class LookupStats : StackObj { private: uint _no_of_samples; uint _worst; uint _worst_count; uint _average; uint _best; uint _best_count; public: LookupStats() : _no_of_samples(0), _worst(0), _worst_count(0), _average(0), _best(INT_MAX), _best_count(0) {} ~LookupStats() { assert(_best <= _worst || _no_of_samples == 0, "sanity"); } void sample(uint value) { ++_no_of_samples; _average += value; if (_worst < value) { _worst = value; _worst_count = 1; } else if (_worst == value) { ++_worst_count; } if (_best > value) { _best = value; _best_count = 1; } else if (_best == value) { ++_best_count; } } void print_on(outputStream* st) const { st->print("best: %2d (%4.1f%%)", _best, (100.0 * _best_count) / _no_of_samples); if (_best_count < _no_of_samples) { st->print("; average: %4.1f; worst: %2d (%4.1f%%)", (1.0 * _average) / _no_of_samples, _worst, (100.0 * _worst_count) / _no_of_samples); } } }; static void print_positive_lookup_stats(Array* secondary_supers, uintx bitmap, outputStream* st) { int num_of_supers = secondary_supers->length(); LookupStats s; for (int i = 0; i < num_of_supers; i++) { Klass* secondary_super = secondary_supers->at(i); int home_slot = Klass::compute_home_slot(secondary_super, bitmap); uint score = 1 + ((i - home_slot) & Klass::SECONDARY_SUPERS_TABLE_MASK); s.sample(score); } st->print("positive_lookup: "); s.print_on(st); } static uint compute_distance_to_nearest_zero(int slot, uintx bitmap) { assert(~bitmap != 0, "no zeroes"); uintx start = rotate_right(bitmap, slot); return count_trailing_zeros(~start); } static void print_negative_lookup_stats(uintx bitmap, outputStream* st) { LookupStats s; for (int slot = 0; slot < Klass::SECONDARY_SUPERS_TABLE_SIZE; slot++) { uint score = compute_distance_to_nearest_zero(slot, bitmap); s.sample(score); } st->print("negative_lookup: "); s.print_on(st); } void Klass::print_secondary_supers_on(outputStream* st) const { if (secondary_supers() != nullptr) { st->print(" - "); st->print("%d elements;", _secondary_supers->length()); st->print_cr(" bitmap: " UINTX_FORMAT_X_0, _secondary_supers_bitmap); if (_secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_EMPTY && _secondary_supers_bitmap != SECONDARY_SUPERS_BITMAP_FULL) { st->print(" - "); print_positive_lookup_stats(secondary_supers(), _secondary_supers_bitmap, st); st->cr(); st->print(" - "); print_negative_lookup_stats(_secondary_supers_bitmap, st); st->cr(); } } else { st->print("null"); } } void Klass::on_secondary_supers_verification_failure(Klass* super, Klass* sub, bool linear_result, bool table_result, const char* msg) { ResourceMark rm; super->print(); sub->print(); fatal("%s: %s implements %s: linear_search: %d; table_lookup: %d", msg, sub->external_name(), super->external_name(), linear_result, table_result); }