/* * Copyright (c) 1997, 2017, 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 "precompiled.hpp" #include "classfile/javaClasses.hpp" #include "classfile/dictionary.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "gc_implementation/shared/markSweep.inline.hpp" #include "gc_interface/collectedHeap.inline.hpp" #include "memory/heapInspection.hpp" #include "memory/metadataFactory.hpp" #include "memory/oopFactory.hpp" #include "memory/resourceArea.hpp" #include "oops/instanceKlass.hpp" #include "oops/klass.inline.hpp" #include "oops/oop.inline2.hpp" #include "runtime/atomic.inline.hpp" #include "runtime/orderAccess.inline.hpp" #include "trace/traceMacros.hpp" #include "utilities/stack.hpp" #include "utilities/macros.hpp" #if INCLUDE_ALL_GCS #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp" #include "gc_implementation/parallelScavenge/psParallelCompact.hpp" #include "gc_implementation/parallelScavenge/psPromotionManager.hpp" #include "gc_implementation/parallelScavenge/psScavenge.hpp" #endif // INCLUDE_ALL_GCS void Klass::set_name(Symbol* n) { _name = n; if (_name != NULL) _name->increment_refcount(); } 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 != NULL) { if (t == k) return true; t = t->super(); } return false; } bool Klass::search_secondary_supers(Klass* k) const { // Put some extra logic here out-of-line, before the search proper. // This cuts down the size of the inline method. // This is necessary, since I am never in my own secondary_super list. if (this == k) return true; // Scan the array-of-objects for a match int cnt = secondary_supers()->length(); for (int i = 0; i < cnt; i++) { if (secondary_supers()->at(i) == k) { ((Klass*)this)->set_secondary_super_cache(k); return true; } } 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 || s->next_sibling() ) // 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) { THROW(vmSymbols::java_lang_ArrayStoreException()); } void Klass::initialize(TRAPS) { ShouldNotReachHere(); } bool Klass::compute_is_subtype_of(Klass* k) { assert(k->is_klass(), "argument must be a class"); return is_subclass_of(k); } 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 NULL; } Method* Klass::uncached_lookup_method(Symbol* name, Symbol* signature, OverpassLookupMode overpass_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 NULL; } void* Klass::operator new(size_t size, ClassLoaderData* loader_data, size_t word_size, TRAPS) throw() { return Metaspace::allocate(loader_data, word_size, /*read_only*/false, MetaspaceObj::ClassType, CHECK_NULL); } Klass::Klass() { Klass* k = this; // Preinitialize supertype information. // A later call to initialize_supers() may update these settings: set_super(NULL); for (juint i = 0; i < Klass::primary_super_limit(); i++) { _primary_supers[i] = NULL; } set_secondary_supers(NULL); set_secondary_super_cache(NULL); _primary_supers[0] = k; set_super_check_offset(in_bytes(primary_supers_offset())); // The constructor is used from init_self_patching_vtbl_list, // which doesn't zero out the memory before calling the constructor. // Need to set the field explicitly to not hit an assert that the field // should be NULL before setting it. _java_mirror = NULL; set_modifier_flags(0); set_layout_helper(Klass::_lh_neutral_value); set_name(NULL); AccessFlags af; af.set_flags(0); set_access_flags(af); set_subklass(NULL); set_next_sibling(NULL); set_next_link(NULL); TRACE_INIT_ID(this); set_prototype_header(markOopDesc::prototype()); set_biased_lock_revocation_count(0); set_last_biased_lock_bulk_revocation_time(0); // The klass doesn't have any references at this point. clear_modified_oops(); clear_accumulated_modified_oops(); _shared_class_path_index = -1; } 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; } bool Klass::can_be_primary_super_slow() const { if (super() == NULL) return true; else if (super()->super_depth() >= primary_super_limit()-1) return false; else return true; } void Klass::initialize_supers(Klass* k, TRAPS) { if (FastSuperclassLimit == 0) { // None of the other machinery matters. set_super(k); return; } if (k == NULL) { set_super(NULL); _primary_supers[0] = this; assert(super_depth() == 0, "Object must already be initialized properly"); } else if (k != super() || k == SystemDictionary::Object_klass()) { assert(super() == NULL || super() == SystemDictionary::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((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) == NULL, "super list padding"); } while (t != NULL) { 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() == NULL) { KlassHandle this_kh (THREAD, this); // 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 == NULL || 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); if (secondaries == NULL) { // secondary_supers set by compute_secondary_supers return; } GrowableArray* primaries = new GrowableArray(extras); for (p = this_kh->super(); !(p == NULL || 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. // The primaries are added in the reverse order, then the secondaries. int new_length = primaries->length() + secondaries->length(); Array* s2 = MetadataFactory::new_array( class_loader_data(), new_length, CHECK); int fill_p = primaries->length(); for (int j = 0; j < fill_p; j++) { s2->at_put(j, primaries->pop()); // add primaries in reverse order. } for( int j = 0; j < secondaries->length(); j++ ) { s2->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 < s2->length(); j++) { assert(s2->at(j) != NULL, "correct bootstrapping order"); } #endif this_kh->set_secondary_supers(s2); } } GrowableArray* Klass::compute_secondary_supers(int num_extra_slots) { assert(num_extra_slots == 0, "override for complex klasses"); set_secondary_supers(Universe::the_empty_klass_array()); return NULL; } Klass* Klass::subklass() const { return _subklass == NULL ? NULL : _subklass; } InstanceKlass* Klass::superklass() const { assert(super() == NULL || super()->oop_is_instance(), "must be instance klass"); return _super == NULL ? NULL : InstanceKlass::cast(_super); } Klass* Klass::next_sibling() const { return _next_sibling == NULL ? NULL : _next_sibling; } void Klass::set_subklass(Klass* s) { assert(s != this, "sanity check"); _subklass = s; } void Klass::set_next_sibling(Klass* s) { assert(s != this, "sanity check"); _next_sibling = s; } void Klass::append_to_sibling_list() { debug_only(verify();) // add ourselves to superklass' subklass list InstanceKlass* super = superklass(); if (super == NULL) return; // special case: class Object assert((!super->is_interface() // interfaces cannot be supers && (super->superklass() == NULL || !is_interface())), "an interface can only be a subklass of Object"); Klass* prev_first_subklass = super->subklass_oop(); if (prev_first_subklass != NULL) { // set our sibling to be the superklass' previous first subklass set_next_sibling(prev_first_subklass); } // make ourselves the superklass' first subklass super->set_subklass(this); debug_only(verify();) } bool Klass::is_loader_alive(BoolObjectClosure* is_alive) { #ifdef ASSERT // The class is alive iff the class loader is alive. oop loader = class_loader(); bool loader_alive = (loader == NULL) || is_alive->do_object_b(loader); #endif // ASSERT // The class is alive if it's mirror is alive (which should be marked if the // loader is alive) unless it's an anoymous class. bool mirror_alive = is_alive->do_object_b(java_mirror()); assert(!mirror_alive || loader_alive, "loader must be alive if the mirror is" " but not the other way around with anonymous classes"); return mirror_alive; } void Klass::clean_weak_klass_links(BoolObjectClosure* is_alive, bool clean_alive_klasses) { if (!ClassUnloading) { return; } Klass* root = SystemDictionary::Object_klass(); Stack stack; stack.push(root); while (!stack.is_empty()) { Klass* current = stack.pop(); assert(current->is_loader_alive(is_alive), "just checking, this should be live"); // Find and set the first alive subklass Klass* sub = current->subklass_oop(); while (sub != NULL && !sub->is_loader_alive(is_alive)) { #ifndef PRODUCT if (TraceClassUnloading && WizardMode) { ResourceMark rm; tty->print_cr("[Unlinking class (subclass) %s]", sub->external_name()); } #endif sub = sub->next_sibling_oop(); } current->set_subklass(sub); if (sub != NULL) { stack.push(sub); } // Find and set the first alive sibling Klass* sibling = current->next_sibling_oop(); while (sibling != NULL && !sibling->is_loader_alive(is_alive)) { if (TraceClassUnloading && WizardMode) { ResourceMark rm; tty->print_cr("[Unlinking class (sibling) %s]", sibling->external_name()); } sibling = sibling->next_sibling_oop(); } current->set_next_sibling(sibling); if (sibling != NULL) { stack.push(sibling); } // Clean the implementors list and method data. if (clean_alive_klasses && current->oop_is_instance()) { InstanceKlass* ik = InstanceKlass::cast(current); ik->clean_weak_instanceklass_links(is_alive); // JVMTI RedefineClasses creates previous versions that are not in // the class hierarchy, so process them here. while ((ik = ik->previous_versions()) != NULL) { ik->clean_weak_instanceklass_links(is_alive); } } } } void Klass::klass_update_barrier_set(oop v) { record_modified_oops(); } // This barrier is used by G1 to remember the old oop values, so // that we don't forget any objects that were live at the snapshot at // the beginning. This function is only used when we write oops into Klasses. void Klass::klass_update_barrier_set_pre(oop* p, oop v) { #if INCLUDE_ALL_GCS if (UseG1GC) { oop obj = *p; if (obj != NULL) { G1SATBCardTableModRefBS::enqueue(obj); } } #endif } void Klass::klass_oop_store(oop* p, oop v) { assert(!Universe::heap()->is_in_reserved((void*)p), "Should store pointer into metadata"); assert(v == NULL || Universe::heap()->is_in_reserved((void*)v), "Should store pointer to an object"); // do the store if (always_do_update_barrier) { klass_oop_store((volatile oop*)p, v); } else { klass_update_barrier_set_pre(p, v); *p = v; klass_update_barrier_set(v); } } void Klass::klass_oop_store(volatile oop* p, oop v) { assert(!Universe::heap()->is_in_reserved((void*)p), "Should store pointer into metadata"); assert(v == NULL || Universe::heap()->is_in_reserved((void*)v), "Should store pointer to an object"); klass_update_barrier_set_pre((oop*)p, v); // Cast away volatile. OrderAccess::release_store_ptr(p, v); klass_update_barrier_set(v); } void Klass::oops_do(OopClosure* cl) { cl->do_oop(&_java_mirror); } void Klass::remove_unshareable_info() { assert (DumpSharedSpaces, "only called for DumpSharedSpaces"); set_subklass(NULL); set_next_sibling(NULL); // Clear the java mirror set_java_mirror(NULL); set_next_link(NULL); // Null out class_loader_data because we don't share that yet. set_class_loader_data(NULL); } void Klass::restore_unshareable_info(ClassLoaderData* loader_data, Handle protection_domain, TRAPS) { TRACE_INIT_ID(this); // 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() == NULL) { // Restore class_loader_data 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); } // Recreate the class mirror. // 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() == NULL) { java_lang_Class::create_mirror(this, class_loader(), protection_domain, CHECK); } } Klass* Klass::array_klass_or_null(int rank) { EXCEPTION_MARK; // No exception can be thrown by array_klass_impl when called with or_null == true. // (In anycase, the execption mark will fail if it do so) return array_klass_impl(true, rank, THREAD); } Klass* Klass::array_klass_or_null() { EXCEPTION_MARK; // No exception can be thrown by array_klass_impl when called with or_null == true. // (In anycase, the execption mark will fail if it do so) return array_klass_impl(true, THREAD); } Klass* Klass::array_klass_impl(bool or_null, int rank, TRAPS) { fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass"); return NULL; } Klass* Klass::array_klass_impl(bool or_null, TRAPS) { fatal("array_klass should be dispatched to InstanceKlass, ObjArrayKlass or TypeArrayKlass"); return NULL; } oop Klass::class_loader() const { return class_loader_data()->class_loader(); } const char* Klass::external_name() const { if (oop_is_instance()) { InstanceKlass* ik = (InstanceKlass*) this; if (ik->is_anonymous()) { assert(EnableInvokeDynamic, ""); intptr_t hash = 0; if (ik->java_mirror() != NULL) { // java_mirror might not be created yet, return 0 as hash. hash = ik->java_mirror()->identity_hash(); } char hash_buf[40]; sprintf(hash_buf, "/" UINTX_FORMAT, (uintx)hash); size_t hash_len = strlen(hash_buf); size_t result_len = name()->utf8_length(); char* result = NEW_RESOURCE_ARRAY(char, result_len + hash_len + 1); name()->as_klass_external_name(result, (int) result_len + 1); assert(strlen(result) == result_len, ""); strcpy(result + result_len, hash_buf); assert(strlen(result) == result_len + hash_len, ""); return result; } } if (name() == NULL) return ""; return name()->as_klass_external_name(); } const char* Klass::signature_name() const { if (name() == NULL) return ""; return name()->as_C_string(); } // Unless overridden, modifier_flags is 0. jint Klass::compute_modifier_flags(TRAPS) const { return 0; } int Klass::atomic_incr_biased_lock_revocation_count() { return (int) Atomic::add(1, &_biased_lock_revocation_count); } // 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(); } void Klass::oop_print_on(oop obj, outputStream* st) { ResourceMark rm; // print title st->print_cr("%s ", internal_name()); obj->print_address_on(st); if (WizardMode) { // print header obj->mark()->print_on(st); } // print class st->print(" - klass: "); obj->klass()->print_value_on(st); 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); } #if INCLUDE_SERVICES // Size Statistics void Klass::collect_statistics(KlassSizeStats *sz) const { sz->_klass_bytes = sz->count(this); sz->_mirror_bytes = sz->count(java_mirror()); sz->_secondary_supers_bytes = sz->count_array(secondary_supers()); sz->_ro_bytes += sz->_secondary_supers_bytes; sz->_rw_bytes += sz->_klass_bytes + sz->_mirror_bytes; } #endif // INCLUDE_SERVICES // 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. assert(Metaspace::contains((address)this), "Should be"); guarantee(this->is_klass(),"should be klass"); if (super() != NULL) { guarantee(super()->is_klass(), "should be klass"); } if (secondary_super_cache() != NULL) { 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 != NULL) { guarantee(ko->is_klass(), "should be klass"); } } if (java_mirror() != NULL) { guarantee(java_mirror()->is_oop(), "should be instance"); } } void Klass::oop_verify_on(oop obj, outputStream* st) { guarantee(obj->is_oop(), "should be oop"); guarantee(obj->klass()->is_klass(), "klass field is not a klass"); } #ifndef PRODUCT bool Klass::verify_vtable_index(int i) { if (oop_is_instance()) { int limit = ((InstanceKlass*)this)->vtable_length()/vtableEntry::size(); assert(i >= 0 && i < limit, err_msg("index %d out of bounds %d", i, limit)); } else { assert(oop_is_array(), "Must be"); int limit = ((ArrayKlass*)this)->vtable_length()/vtableEntry::size(); assert(i >= 0 && i < limit, err_msg("index %d out of bounds %d", i, limit)); } return true; } bool Klass::verify_itable_index(int i) { assert(oop_is_instance(), ""); int method_count = klassItable::method_count_for_interface(this); assert(i >= 0 && i < method_count, "index out of bounds"); return true; } #endif /////////////// Unit tests /////////////// #ifndef PRODUCT class TestKlass { public: static void test_oop_is_instanceClassLoader() { assert(SystemDictionary::ClassLoader_klass()->oop_is_instanceClassLoader(), "assert"); assert(!SystemDictionary::String_klass()->oop_is_instanceClassLoader(), "assert"); } }; void TestKlass_test() { TestKlass::test_oop_is_instanceClassLoader(); } #endif