/* * Copyright (c) 1997, 2014, 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/systemDictionary.hpp" #include "classfile/verifier.hpp" #include "classfile/vmSymbols.hpp" #include "compiler/compileBroker.hpp" #include "gc_implementation/shared/markSweep.inline.hpp" #include "gc_interface/collectedHeap.inline.hpp" #include "interpreter/oopMapCache.hpp" #include "interpreter/rewriter.hpp" #include "jvmtifiles/jvmti.h" #include "memory/genOopClosures.inline.hpp" #include "memory/oopFactory.hpp" #include "memory/permGen.hpp" #include "oops/fieldStreams.hpp" #include "oops/instanceKlass.hpp" #include "oops/instanceMirrorKlass.hpp" #include "oops/instanceOop.hpp" #include "oops/methodOop.hpp" #include "oops/objArrayKlassKlass.hpp" #include "oops/oop.inline.hpp" #include "oops/symbol.hpp" #include "prims/jvmtiExport.hpp" #include "prims/jvmtiRedefineClassesTrace.hpp" #include "runtime/fieldDescriptor.hpp" #include "runtime/handles.inline.hpp" #include "runtime/javaCalls.hpp" #include "runtime/mutexLocker.hpp" #include "services/threadService.hpp" #include "utilities/dtrace.hpp" #ifdef TARGET_OS_FAMILY_linux # include "thread_linux.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_solaris # include "thread_solaris.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_windows # include "thread_windows.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_bsd # include "thread_bsd.inline.hpp" #endif #ifndef SERIALGC #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" #include "gc_implementation/g1/g1OopClosures.inline.hpp" #include "gc_implementation/g1/g1RemSet.inline.hpp" #include "gc_implementation/g1/heapRegionSeq.inline.hpp" #include "gc_implementation/parNew/parOopClosures.inline.hpp" #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp" #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp" #include "oops/oop.pcgc.inline.hpp" #endif #ifdef COMPILER1 #include "c1/c1_Compiler.hpp" #endif #ifdef DTRACE_ENABLED #ifndef USDT2 HS_DTRACE_PROBE_DECL4(hotspot, class__initialization__required, char*, intptr_t, oop, intptr_t); HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__recursive, char*, intptr_t, oop, intptr_t, int); HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__concurrent, char*, intptr_t, oop, intptr_t, int); HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__erroneous, char*, intptr_t, oop, intptr_t, int); HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__super__failed, char*, intptr_t, oop, intptr_t, int); HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__clinit, char*, intptr_t, oop, intptr_t, int); HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__error, char*, intptr_t, oop, intptr_t, int); HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__end, char*, intptr_t, oop, intptr_t, int); #define DTRACE_CLASSINIT_PROBE(type, clss, thread_type) \ { \ char* data = NULL; \ int len = 0; \ Symbol* name = (clss)->name(); \ if (name != NULL) { \ data = (char*)name->bytes(); \ len = name->utf8_length(); \ } \ HS_DTRACE_PROBE4(hotspot, class__initialization__##type, \ data, len, (clss)->class_loader(), thread_type); \ } #define DTRACE_CLASSINIT_PROBE_WAIT(type, clss, thread_type, wait) \ { \ char* data = NULL; \ int len = 0; \ Symbol* name = (clss)->name(); \ if (name != NULL) { \ data = (char*)name->bytes(); \ len = name->utf8_length(); \ } \ HS_DTRACE_PROBE5(hotspot, class__initialization__##type, \ data, len, (clss)->class_loader(), thread_type, wait); \ } #else /* USDT2 */ #define HOTSPOT_CLASS_INITIALIZATION_required HOTSPOT_CLASS_INITIALIZATION_REQUIRED #define HOTSPOT_CLASS_INITIALIZATION_recursive HOTSPOT_CLASS_INITIALIZATION_RECURSIVE #define HOTSPOT_CLASS_INITIALIZATION_concurrent HOTSPOT_CLASS_INITIALIZATION_CONCURRENT #define HOTSPOT_CLASS_INITIALIZATION_erroneous HOTSPOT_CLASS_INITIALIZATION_ERRONEOUS #define HOTSPOT_CLASS_INITIALIZATION_super__failed HOTSPOT_CLASS_INITIALIZATION_SUPER_FAILED #define HOTSPOT_CLASS_INITIALIZATION_clinit HOTSPOT_CLASS_INITIALIZATION_CLINIT #define HOTSPOT_CLASS_INITIALIZATION_error HOTSPOT_CLASS_INITIALIZATION_ERROR #define HOTSPOT_CLASS_INITIALIZATION_end HOTSPOT_CLASS_INITIALIZATION_END #define DTRACE_CLASSINIT_PROBE(type, clss, thread_type) \ { \ char* data = NULL; \ int len = 0; \ Symbol* name = (clss)->name(); \ if (name != NULL) { \ data = (char*)name->bytes(); \ len = name->utf8_length(); \ } \ HOTSPOT_CLASS_INITIALIZATION_##type( \ data, len, (clss)->class_loader(), thread_type); \ } #define DTRACE_CLASSINIT_PROBE_WAIT(type, clss, thread_type, wait) \ { \ char* data = NULL; \ int len = 0; \ Symbol* name = (clss)->name(); \ if (name != NULL) { \ data = (char*)name->bytes(); \ len = name->utf8_length(); \ } \ HOTSPOT_CLASS_INITIALIZATION_##type( \ data, len, (clss)->class_loader(), thread_type, wait); \ } #endif /* USDT2 */ #else // ndef DTRACE_ENABLED #define DTRACE_CLASSINIT_PROBE(type, clss, thread_type) #define DTRACE_CLASSINIT_PROBE_WAIT(type, clss, thread_type, wait) #endif // ndef DTRACE_ENABLED volatile int instanceKlass::_total_instanceKlass_count = 0; bool instanceKlass::should_be_initialized() const { return !is_initialized(); } klassVtable* instanceKlass::vtable() const { return new klassVtable(as_klassOop(), start_of_vtable(), vtable_length() / vtableEntry::size()); } klassItable* instanceKlass::itable() const { return new klassItable(as_klassOop()); } void instanceKlass::eager_initialize(Thread *thread) { if (!EagerInitialization) return; if (this->is_not_initialized()) { // abort if the the class has a class initializer if (this->class_initializer() != NULL) return; // abort if it is java.lang.Object (initialization is handled in genesis) klassOop super = this->super(); if (super == NULL) return; // abort if the super class should be initialized if (!instanceKlass::cast(super)->is_initialized()) return; // call body to expose the this pointer instanceKlassHandle this_oop(thread, this->as_klassOop()); eager_initialize_impl(this_oop); } } void instanceKlass::eager_initialize_impl(instanceKlassHandle this_oop) { EXCEPTION_MARK; ObjectLocker ol(this_oop, THREAD); // abort if someone beat us to the initialization if (!this_oop->is_not_initialized()) return; // note: not equivalent to is_initialized() ClassState old_state = this_oop->init_state(); link_class_impl(this_oop, true, THREAD); if (HAS_PENDING_EXCEPTION) { CLEAR_PENDING_EXCEPTION; // Abort if linking the class throws an exception. // Use a test to avoid redundantly resetting the state if there's // no change. Set_init_state() asserts that state changes make // progress, whereas here we might just be spinning in place. if( old_state != this_oop->_init_state ) this_oop->set_init_state (old_state); } else { // linking successfull, mark class as initialized this_oop->set_init_state (fully_initialized); // trace if (TraceClassInitialization) { ResourceMark rm(THREAD); tty->print_cr("[Initialized %s without side effects]", this_oop->external_name()); } } } // See "The Virtual Machine Specification" section 2.16.5 for a detailed explanation of the class initialization // process. The step comments refers to the procedure described in that section. // Note: implementation moved to static method to expose the this pointer. void instanceKlass::initialize(TRAPS) { if (this->should_be_initialized()) { HandleMark hm(THREAD); instanceKlassHandle this_oop(THREAD, this->as_klassOop()); initialize_impl(this_oop, CHECK); // Note: at this point the class may be initialized // OR it may be in the state of being initialized // in case of recursive initialization! } else { assert(is_initialized(), "sanity check"); } } bool instanceKlass::verify_code( instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS) { // 1) Verify the bytecodes Verifier::Mode mode = throw_verifyerror ? Verifier::ThrowException : Verifier::NoException; return Verifier::verify(this_oop, mode, this_oop->should_verify_class(), CHECK_false); } // Used exclusively by the shared spaces dump mechanism to prevent // classes mapped into the shared regions in new VMs from appearing linked. void instanceKlass::unlink_class() { assert(is_linked(), "must be linked"); _init_state = loaded; } void instanceKlass::link_class(TRAPS) { assert(is_loaded(), "must be loaded"); if (!is_linked()) { instanceKlassHandle this_oop(THREAD, this->as_klassOop()); link_class_impl(this_oop, true, CHECK); } } // Called to verify that a class can link during initialization, without // throwing a VerifyError. bool instanceKlass::link_class_or_fail(TRAPS) { assert(is_loaded(), "must be loaded"); if (!is_linked()) { instanceKlassHandle this_oop(THREAD, this->as_klassOop()); link_class_impl(this_oop, false, CHECK_false); } return is_linked(); } bool instanceKlass::link_class_impl( instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS) { // check for error state if (this_oop->is_in_error_state()) { ResourceMark rm(THREAD); THROW_MSG_(vmSymbols::java_lang_NoClassDefFoundError(), this_oop->external_name(), false); } // return if already verified if (this_oop->is_linked()) { return true; } // Timing // timer handles recursion assert(THREAD->is_Java_thread(), "non-JavaThread in link_class_impl"); JavaThread* jt = (JavaThread*)THREAD; // link super class before linking this class instanceKlassHandle super(THREAD, this_oop->super()); if (super.not_null()) { if (super->is_interface()) { // check if super class is an interface ResourceMark rm(THREAD); Exceptions::fthrow( THREAD_AND_LOCATION, vmSymbols::java_lang_IncompatibleClassChangeError(), "class %s has interface %s as super class", this_oop->external_name(), super->external_name() ); return false; } link_class_impl(super, throw_verifyerror, CHECK_false); } // link all interfaces implemented by this class before linking this class objArrayHandle interfaces (THREAD, this_oop->local_interfaces()); int num_interfaces = interfaces->length(); for (int index = 0; index < num_interfaces; index++) { HandleMark hm(THREAD); instanceKlassHandle ih(THREAD, klassOop(interfaces->obj_at(index))); link_class_impl(ih, throw_verifyerror, CHECK_false); } // in case the class is linked in the process of linking its superclasses if (this_oop->is_linked()) { return true; } // trace only the link time for this klass that includes // the verification time PerfClassTraceTime vmtimer(ClassLoader::perf_class_link_time(), ClassLoader::perf_class_link_selftime(), ClassLoader::perf_classes_linked(), jt->get_thread_stat()->perf_recursion_counts_addr(), jt->get_thread_stat()->perf_timers_addr(), PerfClassTraceTime::CLASS_LINK); // verification & rewriting { ObjectLocker ol(this_oop, THREAD); // rewritten will have been set if loader constraint error found // on an earlier link attempt // don't verify or rewrite if already rewritten if (!this_oop->is_linked()) { if (!this_oop->is_rewritten()) { { // Timer includes any side effects of class verification (resolution, // etc), but not recursive entry into verify_code(). PerfClassTraceTime timer(ClassLoader::perf_class_verify_time(), ClassLoader::perf_class_verify_selftime(), ClassLoader::perf_classes_verified(), jt->get_thread_stat()->perf_recursion_counts_addr(), jt->get_thread_stat()->perf_timers_addr(), PerfClassTraceTime::CLASS_VERIFY); bool verify_ok = verify_code(this_oop, throw_verifyerror, THREAD); if (!verify_ok) { return false; } } // Just in case a side-effect of verify linked this class already // (which can sometimes happen since the verifier loads classes // using custom class loaders, which are free to initialize things) if (this_oop->is_linked()) { return true; } // also sets rewritten this_oop->rewrite_class(CHECK_false); } // relocate jsrs and link methods after they are all rewritten this_oop->relocate_and_link_methods(CHECK_false); // Initialize the vtable and interface table after // methods have been rewritten since rewrite may // fabricate new methodOops. // also does loader constraint checking if (!this_oop()->is_shared()) { ResourceMark rm(THREAD); this_oop->vtable()->initialize_vtable(true, CHECK_false); this_oop->itable()->initialize_itable(true, CHECK_false); } #ifdef ASSERT else { ResourceMark rm(THREAD); this_oop->vtable()->verify(tty, true); // In case itable verification is ever added. // this_oop->itable()->verify(tty, true); } #endif this_oop->set_init_state(linked); if (JvmtiExport::should_post_class_prepare()) { Thread *thread = THREAD; assert(thread->is_Java_thread(), "thread->is_Java_thread()"); JvmtiExport::post_class_prepare((JavaThread *) thread, this_oop()); } } } return true; } // Rewrite the byte codes of all of the methods of a class. // The rewriter must be called exactly once. Rewriting must happen after // verification but before the first method of the class is executed. void instanceKlass::rewrite_class(TRAPS) { assert(is_loaded(), "must be loaded"); instanceKlassHandle this_oop(THREAD, this->as_klassOop()); if (this_oop->is_rewritten()) { assert(this_oop()->is_shared(), "rewriting an unshared class?"); return; } Rewriter::rewrite(this_oop, CHECK); this_oop->set_rewritten(); } // Now relocate and link method entry points after class is rewritten. // This is outside is_rewritten flag. In case of an exception, it can be // executed more than once. void instanceKlass::relocate_and_link_methods(TRAPS) { assert(is_loaded(), "must be loaded"); instanceKlassHandle this_oop(THREAD, this->as_klassOop()); Rewriter::relocate_and_link(this_oop, CHECK); } void instanceKlass::initialize_impl(instanceKlassHandle this_oop, TRAPS) { // Make sure klass is linked (verified) before initialization // A class could already be verified, since it has been reflected upon. this_oop->link_class(CHECK); DTRACE_CLASSINIT_PROBE(required, instanceKlass::cast(this_oop()), -1); bool wait = false; // refer to the JVM book page 47 for description of steps // Step 1 { ObjectLocker ol(this_oop, THREAD); Thread *self = THREAD; // it's passed the current thread // Step 2 // If we were to use wait() instead of waitInterruptibly() then // we might end up throwing IE from link/symbol resolution sites // that aren't expected to throw. This would wreak havoc. See 6320309. while(this_oop->is_being_initialized() && !this_oop->is_reentrant_initialization(self)) { wait = true; ol.waitUninterruptibly(CHECK); } // Step 3 if (this_oop->is_being_initialized() && this_oop->is_reentrant_initialization(self)) { DTRACE_CLASSINIT_PROBE_WAIT(recursive, instanceKlass::cast(this_oop()), -1,wait); return; } // Step 4 if (this_oop->is_initialized()) { DTRACE_CLASSINIT_PROBE_WAIT(concurrent, instanceKlass::cast(this_oop()), -1,wait); return; } // Step 5 if (this_oop->is_in_error_state()) { DTRACE_CLASSINIT_PROBE_WAIT(erroneous, instanceKlass::cast(this_oop()), -1,wait); ResourceMark rm(THREAD); const char* desc = "Could not initialize class "; const char* className = this_oop->external_name(); size_t msglen = strlen(desc) + strlen(className) + 1; char* message = NEW_RESOURCE_ARRAY(char, msglen); if (NULL == message) { // Out of memory: can't create detailed error message THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), className); } else { jio_snprintf(message, msglen, "%s%s", desc, className); THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), message); } } // Step 6 this_oop->set_init_state(being_initialized); this_oop->set_init_thread(self); } // Step 7 klassOop super_klass = this_oop->super(); if (super_klass != NULL && !this_oop->is_interface() && Klass::cast(super_klass)->should_be_initialized()) { Klass::cast(super_klass)->initialize(THREAD); if (HAS_PENDING_EXCEPTION) { Handle e(THREAD, PENDING_EXCEPTION); CLEAR_PENDING_EXCEPTION; { EXCEPTION_MARK; this_oop->set_initialization_state_and_notify(initialization_error, THREAD); // Locks object, set state, and notify all waiting threads CLEAR_PENDING_EXCEPTION; // ignore any exception thrown, superclass initialization error is thrown below } DTRACE_CLASSINIT_PROBE_WAIT(super__failed, instanceKlass::cast(this_oop()), -1,wait); THROW_OOP(e()); } } // Step 8 { assert(THREAD->is_Java_thread(), "non-JavaThread in initialize_impl"); JavaThread* jt = (JavaThread*)THREAD; DTRACE_CLASSINIT_PROBE_WAIT(clinit, instanceKlass::cast(this_oop()), -1,wait); // Timer includes any side effects of class initialization (resolution, // etc), but not recursive entry into call_class_initializer(). PerfClassTraceTime timer(ClassLoader::perf_class_init_time(), ClassLoader::perf_class_init_selftime(), ClassLoader::perf_classes_inited(), jt->get_thread_stat()->perf_recursion_counts_addr(), jt->get_thread_stat()->perf_timers_addr(), PerfClassTraceTime::CLASS_CLINIT); this_oop->call_class_initializer(THREAD); } // Step 9 if (!HAS_PENDING_EXCEPTION) { this_oop->set_initialization_state_and_notify(fully_initialized, CHECK); { ResourceMark rm(THREAD); debug_only(this_oop->vtable()->verify(tty, true);) } } else { // Step 10 and 11 Handle e(THREAD, PENDING_EXCEPTION); CLEAR_PENDING_EXCEPTION; { EXCEPTION_MARK; this_oop->set_initialization_state_and_notify(initialization_error, THREAD); CLEAR_PENDING_EXCEPTION; // ignore any exception thrown, class initialization error is thrown below } DTRACE_CLASSINIT_PROBE_WAIT(error, instanceKlass::cast(this_oop()), -1,wait); if (e->is_a(SystemDictionary::Error_klass())) { THROW_OOP(e()); } else { JavaCallArguments args(e); THROW_ARG(vmSymbols::java_lang_ExceptionInInitializerError(), vmSymbols::throwable_void_signature(), &args); } } DTRACE_CLASSINIT_PROBE_WAIT(end, instanceKlass::cast(this_oop()), -1,wait); } // Note: implementation moved to static method to expose the this pointer. void instanceKlass::set_initialization_state_and_notify(ClassState state, TRAPS) { instanceKlassHandle kh(THREAD, this->as_klassOop()); set_initialization_state_and_notify_impl(kh, state, CHECK); } void instanceKlass::set_initialization_state_and_notify_impl(instanceKlassHandle this_oop, ClassState state, TRAPS) { ObjectLocker ol(this_oop, THREAD); this_oop->set_init_state(state); ol.notify_all(CHECK); } // The embedded _implementor field can only record one implementor. // When there are more than one implementors, the _implementor field // is set to the interface klassOop itself. Following are the possible // values for the _implementor field: // NULL - no implementor // implementor klassOop - one implementor // self - more than one implementor // // The _implementor field only exists for interfaces. void instanceKlass::add_implementor(klassOop k) { assert(Compile_lock->owned_by_self(), ""); assert(is_interface(), "not interface"); // Filter out my subinterfaces. // (Note: Interfaces are never on the subklass list.) if (instanceKlass::cast(k)->is_interface()) return; // Filter out subclasses whose supers already implement me. // (Note: CHA must walk subclasses of direct implementors // in order to locate indirect implementors.) klassOop sk = instanceKlass::cast(k)->super(); if (sk != NULL && instanceKlass::cast(sk)->implements_interface(as_klassOop())) // We only need to check one immediate superclass, since the // implements_interface query looks at transitive_interfaces. // Any supers of the super have the same (or fewer) transitive_interfaces. return; klassOop ik = implementor(); if (ik == NULL) { set_implementor(k); } else if (ik != this->as_klassOop()) { // There is already an implementor. Use itself as an indicator of // more than one implementors. set_implementor(this->as_klassOop()); } // The implementor also implements the transitive_interfaces for (int index = 0; index < local_interfaces()->length(); index++) { instanceKlass::cast(klassOop(local_interfaces()->obj_at(index)))->add_implementor(k); } } void instanceKlass::init_implementor() { if (is_interface()) { set_implementor(NULL); } } void instanceKlass::process_interfaces(Thread *thread) { // link this class into the implementors list of every interface it implements KlassHandle this_as_oop (thread, this->as_klassOop()); for (int i = local_interfaces()->length() - 1; i >= 0; i--) { assert(local_interfaces()->obj_at(i)->is_klass(), "must be a klass"); instanceKlass* interf = instanceKlass::cast(klassOop(local_interfaces()->obj_at(i))); assert(interf->is_interface(), "expected interface"); interf->add_implementor(this_as_oop()); } } bool instanceKlass::can_be_primary_super_slow() const { if (is_interface()) return false; else return Klass::can_be_primary_super_slow(); } objArrayOop instanceKlass::compute_secondary_supers(int num_extra_slots, TRAPS) { // The secondaries are the implemented interfaces. instanceKlass* ik = instanceKlass::cast(as_klassOop()); objArrayHandle interfaces (THREAD, ik->transitive_interfaces()); int num_secondaries = num_extra_slots + interfaces->length(); if (num_secondaries == 0) { return Universe::the_empty_system_obj_array(); } else if (num_extra_slots == 0) { return interfaces(); } else { // a mix of both objArrayOop secondaries = oopFactory::new_system_objArray(num_secondaries, CHECK_NULL); for (int i = 0; i < interfaces->length(); i++) { secondaries->obj_at_put(num_extra_slots+i, interfaces->obj_at(i)); } return secondaries; } } bool instanceKlass::compute_is_subtype_of(klassOop k) { if (Klass::cast(k)->is_interface()) { return implements_interface(k); } else { return Klass::compute_is_subtype_of(k); } } bool instanceKlass::implements_interface(klassOop k) const { if (as_klassOop() == k) return true; assert(Klass::cast(k)->is_interface(), "should be an interface class"); for (int i = 0; i < transitive_interfaces()->length(); i++) { if (transitive_interfaces()->obj_at(i) == k) { return true; } } return false; } objArrayOop instanceKlass::allocate_objArray(int n, int length, TRAPS) { if (length < 0) THROW_0(vmSymbols::java_lang_NegativeArraySizeException()); if (length > arrayOopDesc::max_array_length(T_OBJECT)) { report_java_out_of_memory("Requested array size exceeds VM limit"); JvmtiExport::post_array_size_exhausted(); THROW_OOP_0(Universe::out_of_memory_error_array_size()); } int size = objArrayOopDesc::object_size(length); klassOop ak = array_klass(n, CHECK_NULL); KlassHandle h_ak (THREAD, ak); objArrayOop o = (objArrayOop)CollectedHeap::array_allocate(h_ak, size, length, CHECK_NULL); return o; } instanceOop instanceKlass::register_finalizer(instanceOop i, TRAPS) { if (TraceFinalizerRegistration) { tty->print("Registered "); i->print_value_on(tty); tty->print_cr(" (" INTPTR_FORMAT ") as finalizable", (address)i); } instanceHandle h_i(THREAD, i); // Pass the handle as argument, JavaCalls::call expects oop as jobjects JavaValue result(T_VOID); JavaCallArguments args(h_i); methodHandle mh (THREAD, Universe::finalizer_register_method()); JavaCalls::call(&result, mh, &args, CHECK_NULL); return h_i(); } instanceOop instanceKlass::allocate_instance(TRAPS) { assert(!oop_is_instanceMirror(), "wrong allocation path"); bool has_finalizer_flag = has_finalizer(); // Query before possible GC int size = size_helper(); // Query before forming handle. KlassHandle h_k(THREAD, as_klassOop()); instanceOop i; i = (instanceOop)CollectedHeap::obj_allocate(h_k, size, CHECK_NULL); if (has_finalizer_flag && !RegisterFinalizersAtInit) { i = register_finalizer(i, CHECK_NULL); } return i; } instanceOop instanceKlass::allocate_permanent_instance(TRAPS) { // Finalizer registration occurs in the Object. constructor // and constructors normally aren't run when allocating perm // instances so simply disallow finalizable perm objects. This can // be relaxed if a need for it is found. assert(!has_finalizer(), "perm objects not allowed to have finalizers"); assert(!oop_is_instanceMirror(), "wrong allocation path"); int size = size_helper(); // Query before forming handle. KlassHandle h_k(THREAD, as_klassOop()); instanceOop i = (instanceOop) CollectedHeap::permanent_obj_allocate(h_k, size, CHECK_NULL); return i; } void instanceKlass::check_valid_for_instantiation(bool throwError, TRAPS) { if (is_interface() || is_abstract()) { ResourceMark rm(THREAD); THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError() : vmSymbols::java_lang_InstantiationException(), external_name()); } if (as_klassOop() == SystemDictionary::Class_klass()) { ResourceMark rm(THREAD); THROW_MSG(throwError ? vmSymbols::java_lang_IllegalAccessError() : vmSymbols::java_lang_IllegalAccessException(), external_name()); } } klassOop instanceKlass::array_klass_impl(bool or_null, int n, TRAPS) { instanceKlassHandle this_oop(THREAD, as_klassOop()); return array_klass_impl(this_oop, or_null, n, THREAD); } klassOop instanceKlass::array_klass_impl(instanceKlassHandle this_oop, bool or_null, int n, TRAPS) { if (this_oop->array_klasses() == NULL) { if (or_null) return NULL; ResourceMark rm; JavaThread *jt = (JavaThread *)THREAD; { // Atomic creation of array_klasses MutexLocker mc(Compile_lock, THREAD); // for vtables MutexLocker ma(MultiArray_lock, THREAD); // Check if update has already taken place if (this_oop->array_klasses() == NULL) { objArrayKlassKlass* oakk = (objArrayKlassKlass*)Universe::objArrayKlassKlassObj()->klass_part(); klassOop k = oakk->allocate_objArray_klass(1, this_oop, CHECK_NULL); this_oop->set_array_klasses(k); } } } // _this will always be set at this point objArrayKlass* oak = (objArrayKlass*)this_oop->array_klasses()->klass_part(); if (or_null) { return oak->array_klass_or_null(n); } return oak->array_klass(n, CHECK_NULL); } klassOop instanceKlass::array_klass_impl(bool or_null, TRAPS) { return array_klass_impl(or_null, 1, THREAD); } void instanceKlass::call_class_initializer(TRAPS) { instanceKlassHandle ik (THREAD, as_klassOop()); call_class_initializer_impl(ik, THREAD); } static int call_class_initializer_impl_counter = 0; // for debugging methodOop instanceKlass::class_initializer() { methodOop clinit = find_method( vmSymbols::class_initializer_name(), vmSymbols::void_method_signature()); if (clinit != NULL && clinit->has_valid_initializer_flags()) { return clinit; } return NULL; } void instanceKlass::call_class_initializer_impl(instanceKlassHandle this_oop, TRAPS) { methodHandle h_method(THREAD, this_oop->class_initializer()); assert(!this_oop->is_initialized(), "we cannot initialize twice"); if (TraceClassInitialization) { tty->print("%d Initializing ", call_class_initializer_impl_counter++); this_oop->name()->print_value(); tty->print_cr("%s (" INTPTR_FORMAT ")", h_method() == NULL ? "(no method)" : "", (address)this_oop()); } if (h_method() != NULL) { JavaCallArguments args; // No arguments JavaValue result(T_VOID); JavaCalls::call(&result, h_method, &args, CHECK); // Static call (no args) } } void instanceKlass::mask_for(methodHandle method, int bci, InterpreterOopMap* entry_for) { // Dirty read, then double-check under a lock. if (_oop_map_cache == NULL) { // Otherwise, allocate a new one. MutexLocker x(OopMapCacheAlloc_lock); // First time use. Allocate a cache in C heap if (_oop_map_cache == NULL) { _oop_map_cache = new OopMapCache(); } } // _oop_map_cache is constant after init; lookup below does is own locking. _oop_map_cache->lookup(method, bci, entry_for); } bool instanceKlass::find_local_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const { for (JavaFieldStream fs(as_klassOop()); !fs.done(); fs.next()) { Symbol* f_name = fs.name(); Symbol* f_sig = fs.signature(); if (f_name == name && f_sig == sig) { fd->initialize(as_klassOop(), fs.index()); return true; } } return false; } void instanceKlass::shared_symbols_iterate(SymbolClosure* closure) { Klass::shared_symbols_iterate(closure); closure->do_symbol(&_generic_signature); closure->do_symbol(&_source_file_name); for (JavaFieldStream fs(this); !fs.done(); fs.next()) { int name_index = fs.name_index(); closure->do_symbol(constants()->symbol_at_addr(name_index)); int sig_index = fs.signature_index(); closure->do_symbol(constants()->symbol_at_addr(sig_index)); } } klassOop instanceKlass::find_interface_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const { const int n = local_interfaces()->length(); for (int i = 0; i < n; i++) { klassOop intf1 = klassOop(local_interfaces()->obj_at(i)); assert(Klass::cast(intf1)->is_interface(), "just checking type"); // search for field in current interface if (instanceKlass::cast(intf1)->find_local_field(name, sig, fd)) { assert(fd->is_static(), "interface field must be static"); return intf1; } // search for field in direct superinterfaces klassOop intf2 = instanceKlass::cast(intf1)->find_interface_field(name, sig, fd); if (intf2 != NULL) return intf2; } // otherwise field lookup fails return NULL; } klassOop instanceKlass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const { // search order according to newest JVM spec (5.4.3.2, p.167). // 1) search for field in current klass if (find_local_field(name, sig, fd)) { return as_klassOop(); } // 2) search for field recursively in direct superinterfaces { klassOop intf = find_interface_field(name, sig, fd); if (intf != NULL) return intf; } // 3) apply field lookup recursively if superclass exists { klassOop supr = super(); if (supr != NULL) return instanceKlass::cast(supr)->find_field(name, sig, fd); } // 4) otherwise field lookup fails return NULL; } klassOop instanceKlass::find_field(Symbol* name, Symbol* sig, bool is_static, fieldDescriptor* fd) const { // search order according to newest JVM spec (5.4.3.2, p.167). // 1) search for field in current klass if (find_local_field(name, sig, fd)) { if (fd->is_static() == is_static) return as_klassOop(); } // 2) search for field recursively in direct superinterfaces if (is_static) { klassOop intf = find_interface_field(name, sig, fd); if (intf != NULL) return intf; } // 3) apply field lookup recursively if superclass exists { klassOop supr = super(); if (supr != NULL) return instanceKlass::cast(supr)->find_field(name, sig, is_static, fd); } // 4) otherwise field lookup fails return NULL; } bool instanceKlass::find_local_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const { for (JavaFieldStream fs(as_klassOop()); !fs.done(); fs.next()) { if (fs.offset() == offset) { fd->initialize(as_klassOop(), fs.index()); if (fd->is_static() == is_static) return true; } } return false; } bool instanceKlass::find_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const { klassOop klass = as_klassOop(); while (klass != NULL) { if (instanceKlass::cast(klass)->find_local_field_from_offset(offset, is_static, fd)) { return true; } klass = Klass::cast(klass)->super(); } return false; } void instanceKlass::methods_do(void f(methodOop method)) { int len = methods()->length(); for (int index = 0; index < len; index++) { methodOop m = methodOop(methods()->obj_at(index)); assert(m->is_method(), "must be method"); f(m); } } void instanceKlass::do_local_static_fields(FieldClosure* cl) { for (JavaFieldStream fs(this); !fs.done(); fs.next()) { if (fs.access_flags().is_static()) { fieldDescriptor fd; fd.initialize(as_klassOop(), fs.index()); cl->do_field(&fd); } } } void instanceKlass::do_local_static_fields(void f(fieldDescriptor*, TRAPS), TRAPS) { instanceKlassHandle h_this(THREAD, as_klassOop()); do_local_static_fields_impl(h_this, f, CHECK); } void instanceKlass::do_local_static_fields_impl(instanceKlassHandle this_oop, void f(fieldDescriptor* fd, TRAPS), TRAPS) { for (JavaFieldStream fs(this_oop()); !fs.done(); fs.next()) { if (fs.access_flags().is_static()) { fieldDescriptor fd; fd.initialize(this_oop(), fs.index()); f(&fd, CHECK); } } } static int compare_fields_by_offset(int* a, int* b) { return a[0] - b[0]; } void instanceKlass::do_nonstatic_fields(FieldClosure* cl) { instanceKlass* super = superklass(); if (super != NULL) { super->do_nonstatic_fields(cl); } fieldDescriptor fd; int length = java_fields_count(); // In DebugInfo nonstatic fields are sorted by offset. int* fields_sorted = NEW_C_HEAP_ARRAY(int, 2*(length+1), mtClass); int j = 0; for (int i = 0; i < length; i += 1) { fd.initialize(as_klassOop(), i); if (!fd.is_static()) { fields_sorted[j + 0] = fd.offset(); fields_sorted[j + 1] = i; j += 2; } } if (j > 0) { length = j; // _sort_Fn is defined in growableArray.hpp. qsort(fields_sorted, length/2, 2*sizeof(int), (_sort_Fn)compare_fields_by_offset); for (int i = 0; i < length; i += 2) { fd.initialize(as_klassOop(), fields_sorted[i + 1]); assert(!fd.is_static() && fd.offset() == fields_sorted[i], "only nonstatic fields"); cl->do_field(&fd); } } FREE_C_HEAP_ARRAY(int, fields_sorted, mtClass); } void instanceKlass::array_klasses_do(void f(klassOop k)) { if (array_klasses() != NULL) arrayKlass::cast(array_klasses())->array_klasses_do(f); } void instanceKlass::with_array_klasses_do(void f(klassOop k)) { f(as_klassOop()); array_klasses_do(f); } #ifdef ASSERT static int linear_search(objArrayOop methods, Symbol* name, Symbol* signature) { int len = methods->length(); for (int index = 0; index < len; index++) { methodOop m = (methodOop)(methods->obj_at(index)); assert(m->is_method(), "must be method"); if (m->signature() == signature && m->name() == name) { return index; } } return -1; } #endif methodOop instanceKlass::find_method(Symbol* name, Symbol* signature) const { return instanceKlass::find_method(methods(), name, signature); } methodOop instanceKlass::find_method(objArrayOop methods, Symbol* name, Symbol* signature) { int len = methods->length(); // methods are sorted, so do binary search int l = 0; int h = len - 1; while (l <= h) { int mid = (l + h) >> 1; methodOop m = (methodOop)methods->obj_at(mid); assert(m->is_method(), "must be method"); int res = m->name()->fast_compare(name); if (res == 0) { // found matching name; do linear search to find matching signature // first, quick check for common case if (m->signature() == signature) return m; // search downwards through overloaded methods int i; for (i = mid - 1; i >= l; i--) { methodOop m = (methodOop)methods->obj_at(i); assert(m->is_method(), "must be method"); if (m->name() != name) break; if (m->signature() == signature) return m; } // search upwards for (i = mid + 1; i <= h; i++) { methodOop m = (methodOop)methods->obj_at(i); assert(m->is_method(), "must be method"); if (m->name() != name) break; if (m->signature() == signature) return m; } // not found #ifdef ASSERT int index = linear_search(methods, name, signature); assert(index == -1, err_msg("binary search should have found entry %d", index)); #endif return NULL; } else if (res < 0) { l = mid + 1; } else { h = mid - 1; } } #ifdef ASSERT int index = linear_search(methods, name, signature); assert(index == -1, err_msg("binary search should have found entry %d", index)); #endif return NULL; } methodOop instanceKlass::uncached_lookup_method(Symbol* name, Symbol* signature) const { klassOop klass = as_klassOop(); while (klass != NULL) { methodOop method = instanceKlass::cast(klass)->find_method(name, signature); if (method != NULL) return method; klass = instanceKlass::cast(klass)->super(); } return NULL; } // lookup a method in all the interfaces that this class implements methodOop instanceKlass::lookup_method_in_all_interfaces(Symbol* name, Symbol* signature) const { objArrayOop all_ifs = instanceKlass::cast(as_klassOop())->transitive_interfaces(); int num_ifs = all_ifs->length(); instanceKlass *ik = NULL; for (int i = 0; i < num_ifs; i++) { ik = instanceKlass::cast(klassOop(all_ifs->obj_at(i))); methodOop m = ik->lookup_method(name, signature); if (m != NULL) { return m; } } return NULL; } /* jni_id_for_impl for jfieldIds only */ JNIid* instanceKlass::jni_id_for_impl(instanceKlassHandle this_oop, int offset) { MutexLocker ml(JfieldIdCreation_lock); // Retry lookup after we got the lock JNIid* probe = this_oop->jni_ids() == NULL ? NULL : this_oop->jni_ids()->find(offset); if (probe == NULL) { // Slow case, allocate new static field identifier probe = new JNIid(this_oop->as_klassOop(), offset, this_oop->jni_ids()); this_oop->set_jni_ids(probe); } return probe; } /* jni_id_for for jfieldIds only */ JNIid* instanceKlass::jni_id_for(int offset) { JNIid* probe = jni_ids() == NULL ? NULL : jni_ids()->find(offset); if (probe == NULL) { probe = jni_id_for_impl(this->as_klassOop(), offset); } return probe; } u2 instanceKlass::enclosing_method_data(int offset) { typeArrayOop inner_class_list = inner_classes(); if (inner_class_list == NULL) { return 0; } int length = inner_class_list->length(); if (length % inner_class_next_offset == 0) { return 0; } else { int index = length - enclosing_method_attribute_size; typeArrayHandle inner_class_list_h(inner_class_list); assert(offset < enclosing_method_attribute_size, "invalid offset"); return inner_class_list_h->ushort_at(index + offset); } } void instanceKlass::set_enclosing_method_indices(u2 class_index, u2 method_index) { typeArrayOop inner_class_list = inner_classes(); assert (inner_class_list != NULL, "_inner_classes list is not set up"); int length = inner_class_list->length(); if (length % inner_class_next_offset == enclosing_method_attribute_size) { int index = length - enclosing_method_attribute_size; typeArrayHandle inner_class_list_h(inner_class_list); inner_class_list_h->ushort_at_put( index + enclosing_method_class_index_offset, class_index); inner_class_list_h->ushort_at_put( index + enclosing_method_method_index_offset, method_index); } } // Lookup or create a jmethodID. // This code is called by the VMThread and JavaThreads so the // locking has to be done very carefully to avoid deadlocks // and/or other cache consistency problems. // jmethodID instanceKlass::get_jmethod_id(instanceKlassHandle ik_h, methodHandle method_h) { size_t idnum = (size_t)method_h->method_idnum(); jmethodID* jmeths = ik_h->methods_jmethod_ids_acquire(); size_t length = 0; jmethodID id = NULL; // We use a double-check locking idiom here because this cache is // performance sensitive. In the normal system, this cache only // transitions from NULL to non-NULL which is safe because we use // release_set_methods_jmethod_ids() to advertise the new cache. // A partially constructed cache should never be seen by a racing // thread. We also use release_store_ptr() to save a new jmethodID // in the cache so a partially constructed jmethodID should never be // seen either. Cache reads of existing jmethodIDs proceed without a // lock, but cache writes of a new jmethodID requires uniqueness and // creation of the cache itself requires no leaks so a lock is // generally acquired in those two cases. // // If the RedefineClasses() API has been used, then this cache can // grow and we'll have transitions from non-NULL to bigger non-NULL. // Cache creation requires no leaks and we require safety between all // cache accesses and freeing of the old cache so a lock is generally // acquired when the RedefineClasses() API has been used. if (jmeths != NULL) { // the cache already exists if (!ik_h->idnum_can_increment()) { // the cache can't grow so we can just get the current values get_jmethod_id_length_value(jmeths, idnum, &length, &id); } else { // cache can grow so we have to be more careful if (Threads::number_of_threads() == 0 || SafepointSynchronize::is_at_safepoint()) { // we're single threaded or at a safepoint - no locking needed get_jmethod_id_length_value(jmeths, idnum, &length, &id); } else { MutexLocker ml(JmethodIdCreation_lock); get_jmethod_id_length_value(jmeths, idnum, &length, &id); } } } // implied else: // we need to allocate a cache so default length and id values are good if (jmeths == NULL || // no cache yet length <= idnum || // cache is too short id == NULL) { // cache doesn't contain entry // This function can be called by the VMThread so we have to do all // things that might block on a safepoint before grabbing the lock. // Otherwise, we can deadlock with the VMThread or have a cache // consistency issue. These vars keep track of what we might have // to free after the lock is dropped. jmethodID to_dealloc_id = NULL; jmethodID* to_dealloc_jmeths = NULL; // may not allocate new_jmeths or use it if we allocate it jmethodID* new_jmeths = NULL; if (length <= idnum) { // allocate a new cache that might be used size_t size = MAX2(idnum+1, (size_t)ik_h->idnum_allocated_count()); new_jmeths = NEW_C_HEAP_ARRAY(jmethodID, size+1, mtClass); memset(new_jmeths, 0, (size+1)*sizeof(jmethodID)); // cache size is stored in element[0], other elements offset by one new_jmeths[0] = (jmethodID)size; } // allocate a new jmethodID that might be used jmethodID new_id = NULL; if (method_h->is_old() && !method_h->is_obsolete()) { // The method passed in is old (but not obsolete), we need to use the current version methodOop current_method = ik_h->method_with_idnum((int)idnum); assert(current_method != NULL, "old and but not obsolete, so should exist"); methodHandle current_method_h(current_method == NULL? method_h() : current_method); new_id = JNIHandles::make_jmethod_id(current_method_h); } else { // It is the current version of the method or an obsolete method, // use the version passed in new_id = JNIHandles::make_jmethod_id(method_h); } if (Threads::number_of_threads() == 0 || SafepointSynchronize::is_at_safepoint()) { // we're single threaded or at a safepoint - no locking needed id = get_jmethod_id_fetch_or_update(ik_h, idnum, new_id, new_jmeths, &to_dealloc_id, &to_dealloc_jmeths); } else { MutexLocker ml(JmethodIdCreation_lock); id = get_jmethod_id_fetch_or_update(ik_h, idnum, new_id, new_jmeths, &to_dealloc_id, &to_dealloc_jmeths); } // The lock has been dropped so we can free resources. // Free up either the old cache or the new cache if we allocated one. if (to_dealloc_jmeths != NULL) { FreeHeap(to_dealloc_jmeths); } // free up the new ID since it wasn't needed if (to_dealloc_id != NULL) { JNIHandles::destroy_jmethod_id(to_dealloc_id); } } return id; } // Common code to fetch the jmethodID from the cache or update the // cache with the new jmethodID. This function should never do anything // that causes the caller to go to a safepoint or we can deadlock with // the VMThread or have cache consistency issues. // jmethodID instanceKlass::get_jmethod_id_fetch_or_update( instanceKlassHandle ik_h, size_t idnum, jmethodID new_id, jmethodID* new_jmeths, jmethodID* to_dealloc_id_p, jmethodID** to_dealloc_jmeths_p) { assert(new_id != NULL, "sanity check"); assert(to_dealloc_id_p != NULL, "sanity check"); assert(to_dealloc_jmeths_p != NULL, "sanity check"); assert(Threads::number_of_threads() == 0 || SafepointSynchronize::is_at_safepoint() || JmethodIdCreation_lock->owned_by_self(), "sanity check"); // reacquire the cache - we are locked, single threaded or at a safepoint jmethodID* jmeths = ik_h->methods_jmethod_ids_acquire(); jmethodID id = NULL; size_t length = 0; if (jmeths == NULL || // no cache yet (length = (size_t)jmeths[0]) <= idnum) { // cache is too short if (jmeths != NULL) { // copy any existing entries from the old cache for (size_t index = 0; index < length; index++) { new_jmeths[index+1] = jmeths[index+1]; } *to_dealloc_jmeths_p = jmeths; // save old cache for later delete } ik_h->release_set_methods_jmethod_ids(jmeths = new_jmeths); } else { // fetch jmethodID (if any) from the existing cache id = jmeths[idnum+1]; *to_dealloc_jmeths_p = new_jmeths; // save new cache for later delete } if (id == NULL) { // No matching jmethodID in the existing cache or we have a new // cache or we just grew the cache. This cache write is done here // by the first thread to win the foot race because a jmethodID // needs to be unique once it is generally available. id = new_id; // The jmethodID cache can be read while unlocked so we have to // make sure the new jmethodID is complete before installing it // in the cache. OrderAccess::release_store_ptr(&jmeths[idnum+1], id); } else { *to_dealloc_id_p = new_id; // save new id for later delete } return id; } // Common code to get the jmethodID cache length and the jmethodID // value at index idnum if there is one. // void instanceKlass::get_jmethod_id_length_value(jmethodID* cache, size_t idnum, size_t *length_p, jmethodID* id_p) { assert(cache != NULL, "sanity check"); assert(length_p != NULL, "sanity check"); assert(id_p != NULL, "sanity check"); // cache size is stored in element[0], other elements offset by one *length_p = (size_t)cache[0]; if (*length_p <= idnum) { // cache is too short *id_p = NULL; } else { *id_p = cache[idnum+1]; // fetch jmethodID (if any) } } // Lookup a jmethodID, NULL if not found. Do no blocking, no allocations, no handles jmethodID instanceKlass::jmethod_id_or_null(methodOop method) { size_t idnum = (size_t)method->method_idnum(); jmethodID* jmeths = methods_jmethod_ids_acquire(); size_t length; // length assigned as debugging crumb jmethodID id = NULL; if (jmeths != NULL && // If there is a cache (length = (size_t)jmeths[0]) > idnum) { // and if it is long enough, id = jmeths[idnum+1]; // Look up the id (may be NULL) } return id; } // Cache an itable index void instanceKlass::set_cached_itable_index(size_t idnum, int index) { int* indices = methods_cached_itable_indices_acquire(); int* to_dealloc_indices = NULL; // We use a double-check locking idiom here because this cache is // performance sensitive. In the normal system, this cache only // transitions from NULL to non-NULL which is safe because we use // release_set_methods_cached_itable_indices() to advertise the // new cache. A partially constructed cache should never be seen // by a racing thread. Cache reads and writes proceed without a // lock, but creation of the cache itself requires no leaks so a // lock is generally acquired in that case. // // If the RedefineClasses() API has been used, then this cache can // grow and we'll have transitions from non-NULL to bigger non-NULL. // Cache creation requires no leaks and we require safety between all // cache accesses and freeing of the old cache so a lock is generally // acquired when the RedefineClasses() API has been used. if (indices == NULL || idnum_can_increment()) { // we need a cache or the cache can grow MutexLocker ml(JNICachedItableIndex_lock); // reacquire the cache to see if another thread already did the work indices = methods_cached_itable_indices_acquire(); size_t length = 0; // cache size is stored in element[0], other elements offset by one if (indices == NULL || (length = (size_t)indices[0]) <= idnum) { size_t size = MAX2(idnum+1, (size_t)idnum_allocated_count()); int* new_indices = NEW_C_HEAP_ARRAY(int, size+1, mtClass); new_indices[0] = (int)size; // copy any existing entries size_t i; for (i = 0; i < length; i++) { new_indices[i+1] = indices[i+1]; } // Set all the rest to -1 for (i = length; i < size; i++) { new_indices[i+1] = -1; } if (indices != NULL) { // We have an old cache to delete so save it for after we // drop the lock. to_dealloc_indices = indices; } release_set_methods_cached_itable_indices(indices = new_indices); } if (idnum_can_increment()) { // this cache can grow so we have to write to it safely indices[idnum+1] = index; } } else { CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops()); } if (!idnum_can_increment()) { // The cache cannot grow and this JNI itable index value does not // have to be unique like a jmethodID. If there is a race to set it, // it doesn't matter. indices[idnum+1] = index; } if (to_dealloc_indices != NULL) { // we allocated a new cache so free the old one FreeHeap(to_dealloc_indices); } } // Retrieve a cached itable index int instanceKlass::cached_itable_index(size_t idnum) { int* indices = methods_cached_itable_indices_acquire(); if (indices != NULL && ((size_t)indices[0]) > idnum) { // indices exist and are long enough, retrieve possible cached return indices[idnum+1]; } return -1; } // // Walk the list of dependent nmethods searching for nmethods which // are dependent on the changes that were passed in and mark them for // deoptimization. Returns the number of nmethods found. // int instanceKlass::mark_dependent_nmethods(DepChange& changes) { assert_locked_or_safepoint(CodeCache_lock); int found = 0; nmethodBucket* b = _dependencies; while (b != NULL) { nmethod* nm = b->get_nmethod(); // since dependencies aren't removed until an nmethod becomes a zombie, // the dependency list may contain nmethods which aren't alive. if (nm->is_alive() && !nm->is_marked_for_deoptimization() && nm->check_dependency_on(changes)) { if (TraceDependencies) { ResourceMark rm; tty->print_cr("Marked for deoptimization"); tty->print_cr(" context = %s", this->external_name()); changes.print(); nm->print(); nm->print_dependencies(); } nm->mark_for_deoptimization(); found++; } b = b->next(); } return found; } // // Add an nmethodBucket to the list of dependencies for this nmethod. // It's possible that an nmethod has multiple dependencies on this klass // so a count is kept for each bucket to guarantee that creation and // deletion of dependencies is consistent. // void instanceKlass::add_dependent_nmethod(nmethod* nm) { assert_locked_or_safepoint(CodeCache_lock); nmethodBucket* b = _dependencies; nmethodBucket* last = NULL; while (b != NULL) { if (nm == b->get_nmethod()) { b->increment(); return; } b = b->next(); } _dependencies = new nmethodBucket(nm, _dependencies); } // // Decrement count of the nmethod in the dependency list and remove // the bucket competely when the count goes to 0. This method must // find a corresponding bucket otherwise there's a bug in the // recording of dependecies. // void instanceKlass::remove_dependent_nmethod(nmethod* nm) { assert_locked_or_safepoint(CodeCache_lock); nmethodBucket* b = _dependencies; nmethodBucket* last = NULL; while (b != NULL) { if (nm == b->get_nmethod()) { if (b->decrement() == 0) { if (last == NULL) { _dependencies = b->next(); } else { last->set_next(b->next()); } delete b; } return; } last = b; b = b->next(); } #ifdef ASSERT tty->print_cr("### %s can't find dependent nmethod:", this->external_name()); nm->print(); #endif // ASSERT ShouldNotReachHere(); } #ifndef PRODUCT void instanceKlass::print_dependent_nmethods(bool verbose) { nmethodBucket* b = _dependencies; int idx = 0; while (b != NULL) { nmethod* nm = b->get_nmethod(); tty->print("[%d] count=%d { ", idx++, b->count()); if (!verbose) { nm->print_on(tty, "nmethod"); tty->print_cr(" } "); } else { nm->print(); nm->print_dependencies(); tty->print_cr("--- } "); } b = b->next(); } } bool instanceKlass::is_dependent_nmethod(nmethod* nm) { nmethodBucket* b = _dependencies; while (b != NULL) { if (nm == b->get_nmethod()) { return true; } b = b->next(); } return false; } #endif //PRODUCT #ifdef ASSERT template void assert_is_in(T *p) { T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop o = oopDesc::decode_heap_oop_not_null(heap_oop); assert(Universe::heap()->is_in(o), "should be in heap"); } } template void assert_is_in_closed_subset(T *p) { T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop o = oopDesc::decode_heap_oop_not_null(heap_oop); assert(Universe::heap()->is_in_closed_subset(o), "should be in closed"); } } template void assert_is_in_reserved(T *p) { T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop o = oopDesc::decode_heap_oop_not_null(heap_oop); assert(Universe::heap()->is_in_reserved(o), "should be in reserved"); } } template void assert_nothing(T *p) {} #else template void assert_is_in(T *p) {} template void assert_is_in_closed_subset(T *p) {} template void assert_is_in_reserved(T *p) {} template void assert_nothing(T *p) {} #endif // ASSERT // // Macros that iterate over areas of oops which are specialized on type of // oop pointer either narrow or wide, depending on UseCompressedOops // // Parameters are: // T - type of oop to point to (either oop or narrowOop) // start_p - starting pointer for region to iterate over // count - number of oops or narrowOops to iterate over // do_oop - action to perform on each oop (it's arbitrary C code which // makes it more efficient to put in a macro rather than making // it a template function) // assert_fn - assert function which is template function because performance // doesn't matter when enabled. #define InstanceKlass_SPECIALIZED_OOP_ITERATE( \ T, start_p, count, do_oop, \ assert_fn) \ { \ T* p = (T*)(start_p); \ T* const end = p + (count); \ while (p < end) { \ (assert_fn)(p); \ do_oop; \ ++p; \ } \ } #define InstanceKlass_SPECIALIZED_OOP_REVERSE_ITERATE( \ T, start_p, count, do_oop, \ assert_fn) \ { \ T* const start = (T*)(start_p); \ T* p = start + (count); \ while (start < p) { \ --p; \ (assert_fn)(p); \ do_oop; \ } \ } #define InstanceKlass_SPECIALIZED_BOUNDED_OOP_ITERATE( \ T, start_p, count, low, high, \ do_oop, assert_fn) \ { \ T* const l = (T*)(low); \ T* const h = (T*)(high); \ assert(mask_bits((intptr_t)l, sizeof(T)-1) == 0 && \ mask_bits((intptr_t)h, sizeof(T)-1) == 0, \ "bounded region must be properly aligned"); \ T* p = (T*)(start_p); \ T* end = p + (count); \ if (p < l) p = l; \ if (end > h) end = h; \ while (p < end) { \ (assert_fn)(p); \ do_oop; \ ++p; \ } \ } // The following macros call specialized macros, passing either oop or // narrowOop as the specialization type. These test the UseCompressedOops // flag. #define InstanceKlass_OOP_MAP_ITERATE(obj, do_oop, assert_fn) \ { \ /* Compute oopmap block range. The common case \ is nonstatic_oop_map_size == 1. */ \ OopMapBlock* map = start_of_nonstatic_oop_maps(); \ OopMapBlock* const end_map = map + nonstatic_oop_map_count(); \ if (UseCompressedOops) { \ while (map < end_map) { \ InstanceKlass_SPECIALIZED_OOP_ITERATE(narrowOop, \ obj->obj_field_addr(map->offset()), map->count(), \ do_oop, assert_fn) \ ++map; \ } \ } else { \ while (map < end_map) { \ InstanceKlass_SPECIALIZED_OOP_ITERATE(oop, \ obj->obj_field_addr(map->offset()), map->count(), \ do_oop, assert_fn) \ ++map; \ } \ } \ } #define InstanceKlass_OOP_MAP_REVERSE_ITERATE(obj, do_oop, assert_fn) \ { \ OopMapBlock* const start_map = start_of_nonstatic_oop_maps(); \ OopMapBlock* map = start_map + nonstatic_oop_map_count(); \ if (UseCompressedOops) { \ while (start_map < map) { \ --map; \ InstanceKlass_SPECIALIZED_OOP_REVERSE_ITERATE(narrowOop, \ obj->obj_field_addr(map->offset()), map->count(), \ do_oop, assert_fn) \ } \ } else { \ while (start_map < map) { \ --map; \ InstanceKlass_SPECIALIZED_OOP_REVERSE_ITERATE(oop, \ obj->obj_field_addr(map->offset()), map->count(), \ do_oop, assert_fn) \ } \ } \ } #define InstanceKlass_BOUNDED_OOP_MAP_ITERATE(obj, low, high, do_oop, \ assert_fn) \ { \ /* Compute oopmap block range. The common case is \ nonstatic_oop_map_size == 1, so we accept the \ usually non-existent extra overhead of examining \ all the maps. */ \ OopMapBlock* map = start_of_nonstatic_oop_maps(); \ OopMapBlock* const end_map = map + nonstatic_oop_map_count(); \ if (UseCompressedOops) { \ while (map < end_map) { \ InstanceKlass_SPECIALIZED_BOUNDED_OOP_ITERATE(narrowOop, \ obj->obj_field_addr(map->offset()), map->count(), \ low, high, \ do_oop, assert_fn) \ ++map; \ } \ } else { \ while (map < end_map) { \ InstanceKlass_SPECIALIZED_BOUNDED_OOP_ITERATE(oop, \ obj->obj_field_addr(map->offset()), map->count(), \ low, high, \ do_oop, assert_fn) \ ++map; \ } \ } \ } void instanceKlass::oop_follow_contents(oop obj) { assert(obj != NULL, "can't follow the content of NULL object"); obj->follow_header(); InstanceKlass_OOP_MAP_ITERATE( \ obj, \ MarkSweep::mark_and_push(p), \ assert_is_in_closed_subset) } #ifndef SERIALGC void instanceKlass::oop_follow_contents(ParCompactionManager* cm, oop obj) { assert(obj != NULL, "can't follow the content of NULL object"); obj->follow_header(cm); InstanceKlass_OOP_MAP_ITERATE( \ obj, \ PSParallelCompact::mark_and_push(cm, p), \ assert_is_in) } #endif // SERIALGC // closure's do_header() method dicates whether the given closure should be // applied to the klass ptr in the object header. #define InstanceKlass_OOP_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \ \ int instanceKlass::oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) { \ SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::ik);\ /* header */ \ if (closure->do_header()) { \ obj->oop_iterate_header(closure); \ } \ InstanceKlass_OOP_MAP_ITERATE( \ obj, \ SpecializationStats:: \ record_do_oop_call##nv_suffix(SpecializationStats::ik); \ (closure)->do_oop##nv_suffix(p), \ assert_is_in_closed_subset) \ return size_helper(); \ } #ifndef SERIALGC #define InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN(OopClosureType, nv_suffix) \ \ int instanceKlass::oop_oop_iterate_backwards##nv_suffix(oop obj, \ OopClosureType* closure) { \ SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::ik); \ /* header */ \ if (closure->do_header()) { \ obj->oop_iterate_header(closure); \ } \ /* instance variables */ \ InstanceKlass_OOP_MAP_REVERSE_ITERATE( \ obj, \ SpecializationStats::record_do_oop_call##nv_suffix(SpecializationStats::ik);\ (closure)->do_oop##nv_suffix(p), \ assert_is_in_closed_subset) \ return size_helper(); \ } #endif // !SERIALGC #define InstanceKlass_OOP_OOP_ITERATE_DEFN_m(OopClosureType, nv_suffix) \ \ int instanceKlass::oop_oop_iterate##nv_suffix##_m(oop obj, \ OopClosureType* closure, \ MemRegion mr) { \ SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::ik);\ if (closure->do_header()) { \ obj->oop_iterate_header(closure, mr); \ } \ InstanceKlass_BOUNDED_OOP_MAP_ITERATE( \ obj, mr.start(), mr.end(), \ (closure)->do_oop##nv_suffix(p), \ assert_is_in_closed_subset) \ return size_helper(); \ } ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_DEFN) ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_DEFN) ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_DEFN_m) ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_DEFN_m) #ifndef SERIALGC ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN) ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN) #endif // !SERIALGC int instanceKlass::oop_adjust_pointers(oop obj) { int size = size_helper(); InstanceKlass_OOP_MAP_ITERATE( \ obj, \ MarkSweep::adjust_pointer(p), \ assert_is_in) obj->adjust_header(); return size; } #ifndef SERIALGC void instanceKlass::oop_push_contents(PSPromotionManager* pm, oop obj) { InstanceKlass_OOP_MAP_REVERSE_ITERATE( \ obj, \ if (PSScavenge::should_scavenge(p)) { \ pm->claim_or_forward_depth(p); \ }, \ assert_nothing ) } int instanceKlass::oop_update_pointers(ParCompactionManager* cm, oop obj) { InstanceKlass_OOP_MAP_ITERATE( \ obj, \ PSParallelCompact::adjust_pointer(p), \ assert_nothing) return size_helper(); } #endif // SERIALGC // This klass is alive but the implementor link is not followed/updated. // Subklass and sibling links are handled by Klass::follow_weak_klass_links void instanceKlass::follow_weak_klass_links( BoolObjectClosure* is_alive, OopClosure* keep_alive) { assert(is_alive->do_object_b(as_klassOop()), "this oop should be live"); if (is_interface()) { if (ClassUnloading) { klassOop impl = implementor(); if (impl != NULL) { if (!is_alive->do_object_b(impl)) { // remove this guy *adr_implementor() = NULL; } } } else { assert(adr_implementor() != NULL, "just checking"); keep_alive->do_oop(adr_implementor()); } } Klass::follow_weak_klass_links(is_alive, keep_alive); } void instanceKlass::remove_unshareable_info() { Klass::remove_unshareable_info(); init_implementor(); } static void clear_all_breakpoints(methodOop m) { m->clear_all_breakpoints(); } void instanceKlass::release_C_heap_structures() { // Deallocate oop map cache if (_oop_map_cache != NULL) { delete _oop_map_cache; _oop_map_cache = NULL; } // Deallocate JNI identifiers for jfieldIDs JNIid::deallocate(jni_ids()); set_jni_ids(NULL); jmethodID* jmeths = methods_jmethod_ids_acquire(); if (jmeths != (jmethodID*)NULL) { release_set_methods_jmethod_ids(NULL); FreeHeap(jmeths); } // Deallocate MemberNameTable { Mutex* lock_or_null = SafepointSynchronize::is_at_safepoint() ? NULL : MemberNameTable_lock; MutexLockerEx ml(lock_or_null, Mutex::_no_safepoint_check_flag); MemberNameTable* mnt = member_names(); if (mnt != NULL) { delete mnt; set_member_names(NULL); } } int* indices = methods_cached_itable_indices_acquire(); if (indices != (int*)NULL) { release_set_methods_cached_itable_indices(NULL); FreeHeap(indices); } // release dependencies nmethodBucket* b = _dependencies; _dependencies = NULL; while (b != NULL) { nmethodBucket* next = b->next(); delete b; b = next; } // Deallocate breakpoint records if (breakpoints() != 0x0) { methods_do(clear_all_breakpoints); assert(breakpoints() == 0x0, "should have cleared breakpoints"); } // deallocate information about previous versions if (_previous_versions != NULL) { for (int i = _previous_versions->length() - 1; i >= 0; i--) { PreviousVersionNode * pv_node = _previous_versions->at(i); delete pv_node; } delete _previous_versions; _previous_versions = NULL; } // deallocate the cached class file if (_cached_class_file_bytes != NULL) { os::free(_cached_class_file_bytes, mtClass); _cached_class_file_bytes = NULL; _cached_class_file_len = 0; } // Decrement symbol reference counts associated with the unloaded class. if (_name != NULL) _name->decrement_refcount(); // unreference array name derived from this class name (arrays of an unloaded // class can't be referenced anymore). if (_array_name != NULL) _array_name->decrement_refcount(); if (_source_file_name != NULL) _source_file_name->decrement_refcount(); // walk constant pool and decrement symbol reference counts _constants->unreference_symbols(); if (_source_debug_extension != NULL) FREE_C_HEAP_ARRAY(char, _source_debug_extension, mtClass); assert(_total_instanceKlass_count >= 1, "Sanity check"); Atomic::dec(&_total_instanceKlass_count); } void instanceKlass::set_source_file_name(Symbol* n) { _source_file_name = n; if (_source_file_name != NULL) _source_file_name->increment_refcount(); } void instanceKlass::set_source_debug_extension(char* array, int length) { if (array == NULL) { _source_debug_extension = NULL; } else { // Adding one to the attribute length in order to store a null terminator // character could cause an overflow because the attribute length is // already coded with an u4 in the classfile, but in practice, it's // unlikely to happen. assert((length+1) > length, "Overflow checking"); char* sde = NEW_C_HEAP_ARRAY(char, (length + 1), mtClass); for (int i = 0; i < length; i++) { sde[i] = array[i]; } sde[length] = '\0'; _source_debug_extension = sde; } } address instanceKlass::static_field_addr(int offset) { return (address)(offset + instanceMirrorKlass::offset_of_static_fields() + (intptr_t)java_mirror()); } const char* instanceKlass::signature_name() const { const char* src = (const char*) (name()->as_C_string()); const int src_length = (int)strlen(src); char* dest = NEW_RESOURCE_ARRAY(char, src_length + 3); int src_index = 0; int dest_index = 0; dest[dest_index++] = 'L'; while (src_index < src_length) { dest[dest_index++] = src[src_index++]; } dest[dest_index++] = ';'; dest[dest_index] = '\0'; return dest; } // different verisons of is_same_class_package bool instanceKlass::is_same_class_package(klassOop class2) { klassOop class1 = as_klassOop(); oop classloader1 = instanceKlass::cast(class1)->class_loader(); Symbol* classname1 = Klass::cast(class1)->name(); if (Klass::cast(class2)->oop_is_objArray()) { class2 = objArrayKlass::cast(class2)->bottom_klass(); } oop classloader2; if (Klass::cast(class2)->oop_is_instance()) { classloader2 = instanceKlass::cast(class2)->class_loader(); } else { assert(Klass::cast(class2)->oop_is_typeArray(), "should be type array"); classloader2 = NULL; } Symbol* classname2 = Klass::cast(class2)->name(); return instanceKlass::is_same_class_package(classloader1, classname1, classloader2, classname2); } bool instanceKlass::is_same_class_package(oop classloader2, Symbol* classname2) { klassOop class1 = as_klassOop(); oop classloader1 = instanceKlass::cast(class1)->class_loader(); Symbol* classname1 = Klass::cast(class1)->name(); return instanceKlass::is_same_class_package(classloader1, classname1, classloader2, classname2); } // return true if two classes are in the same package, classloader // and classname information is enough to determine a class's package bool instanceKlass::is_same_class_package(oop class_loader1, Symbol* class_name1, oop class_loader2, Symbol* class_name2) { if (class_loader1 != class_loader2) { return false; } else if (class_name1 == class_name2) { return true; // skip painful bytewise comparison } else { ResourceMark rm; // The Symbol*'s are in UTF8 encoding. Since we only need to check explicitly // for ASCII characters ('/', 'L', '['), we can keep them in UTF8 encoding. // Otherwise, we just compare jbyte values between the strings. const jbyte *name1 = class_name1->base(); const jbyte *name2 = class_name2->base(); const jbyte *last_slash1 = UTF8::strrchr(name1, class_name1->utf8_length(), '/'); const jbyte *last_slash2 = UTF8::strrchr(name2, class_name2->utf8_length(), '/'); if ((last_slash1 == NULL) || (last_slash2 == NULL)) { // One of the two doesn't have a package. Only return true // if the other one also doesn't have a package. return last_slash1 == last_slash2; } else { // Skip over '['s if (*name1 == '[') { do { name1++; } while (*name1 == '['); if (*name1 != 'L') { // Something is terribly wrong. Shouldn't be here. return false; } } if (*name2 == '[') { do { name2++; } while (*name2 == '['); if (*name2 != 'L') { // Something is terribly wrong. Shouldn't be here. return false; } } // Check that package part is identical int length1 = last_slash1 - name1; int length2 = last_slash2 - name2; return UTF8::equal(name1, length1, name2, length2); } } } // Returns true iff super_method can be overridden by a method in targetclassname // See JSL 3rd edition 8.4.6.1 // Assumes name-signature match // "this" is instanceKlass of super_method which must exist // note that the instanceKlass of the method in the targetclassname has not always been created yet bool instanceKlass::is_override(methodHandle super_method, Handle targetclassloader, Symbol* targetclassname, TRAPS) { // Private methods can not be overridden if (super_method->is_private()) { return false; } // If super method is accessible, then override if ((super_method->is_protected()) || (super_method->is_public())) { return true; } // Package-private methods are not inherited outside of package assert(super_method->is_package_private(), "must be package private"); return(is_same_class_package(targetclassloader(), targetclassname)); } /* defined for now in jvm.cpp, for historical reasons *-- klassOop instanceKlass::compute_enclosing_class_impl(instanceKlassHandle self, Symbol*& simple_name_result, TRAPS) { ... } */ // tell if two classes have the same enclosing class (at package level) bool instanceKlass::is_same_package_member_impl(instanceKlassHandle class1, klassOop class2_oop, TRAPS) { if (class2_oop == class1->as_klassOop()) return true; if (!Klass::cast(class2_oop)->oop_is_instance()) return false; instanceKlassHandle class2(THREAD, class2_oop); // must be in same package before we try anything else if (!class1->is_same_class_package(class2->class_loader(), class2->name())) return false; // As long as there is an outer1.getEnclosingClass, // shift the search outward. instanceKlassHandle outer1 = class1; for (;;) { // As we walk along, look for equalities between outer1 and class2. // Eventually, the walks will terminate as outer1 stops // at the top-level class around the original class. bool ignore_inner_is_member; klassOop next = outer1->compute_enclosing_class(&ignore_inner_is_member, CHECK_false); if (next == NULL) break; if (next == class2()) return true; outer1 = instanceKlassHandle(THREAD, next); } // Now do the same for class2. instanceKlassHandle outer2 = class2; for (;;) { bool ignore_inner_is_member; klassOop next = outer2->compute_enclosing_class(&ignore_inner_is_member, CHECK_false); if (next == NULL) break; // Might as well check the new outer against all available values. if (next == class1()) return true; if (next == outer1()) return true; outer2 = instanceKlassHandle(THREAD, next); } // If by this point we have not found an equality between the // two classes, we know they are in separate package members. return false; } jint instanceKlass::compute_modifier_flags(TRAPS) const { klassOop k = as_klassOop(); jint access = access_flags().as_int(); // But check if it happens to be member class. instanceKlassHandle ik(THREAD, k); InnerClassesIterator iter(ik); for (; !iter.done(); iter.next()) { int ioff = iter.inner_class_info_index(); // Inner class attribute can be zero, skip it. // Strange but true: JVM spec. allows null inner class refs. if (ioff == 0) continue; // only look at classes that are already loaded // since we are looking for the flags for our self. Symbol* inner_name = ik->constants()->klass_name_at(ioff); if ((ik->name() == inner_name)) { // This is really a member class. access = iter.inner_access_flags(); break; } } // Remember to strip ACC_SUPER bit return (access & (~JVM_ACC_SUPER)) & JVM_ACC_WRITTEN_FLAGS; } jint instanceKlass::jvmti_class_status() const { jint result = 0; if (is_linked()) { result |= JVMTI_CLASS_STATUS_VERIFIED | JVMTI_CLASS_STATUS_PREPARED; } if (is_initialized()) { assert(is_linked(), "Class status is not consistent"); result |= JVMTI_CLASS_STATUS_INITIALIZED; } if (is_in_error_state()) { result |= JVMTI_CLASS_STATUS_ERROR; } return result; } methodOop instanceKlass::method_at_itable(klassOop holder, int index, TRAPS) { itableOffsetEntry* ioe = (itableOffsetEntry*)start_of_itable(); int method_table_offset_in_words = ioe->offset()/wordSize; int nof_interfaces = (method_table_offset_in_words - itable_offset_in_words()) / itableOffsetEntry::size(); for (int cnt = 0 ; ; cnt ++, ioe ++) { // If the interface isn't implemented by the receiver class, // the VM should throw IncompatibleClassChangeError. if (cnt >= nof_interfaces) { THROW_0(vmSymbols::java_lang_IncompatibleClassChangeError()); } klassOop ik = ioe->interface_klass(); if (ik == holder) break; } itableMethodEntry* ime = ioe->first_method_entry(as_klassOop()); methodOop m = ime[index].method(); if (m == NULL) { THROW_0(vmSymbols::java_lang_AbstractMethodError()); } return m; } // On-stack replacement stuff void instanceKlass::add_osr_nmethod(nmethod* n) { // only one compilation can be active NEEDS_CLEANUP // This is a short non-blocking critical region, so the no safepoint check is ok. OsrList_lock->lock_without_safepoint_check(); assert(n->is_osr_method(), "wrong kind of nmethod"); n->set_osr_link(osr_nmethods_head()); set_osr_nmethods_head(n); // Raise the highest osr level if necessary if (TieredCompilation) { methodOop m = n->method(); m->set_highest_osr_comp_level(MAX2(m->highest_osr_comp_level(), n->comp_level())); } // Remember to unlock again OsrList_lock->unlock(); // Get rid of the osr methods for the same bci that have lower levels. if (TieredCompilation) { for (int l = CompLevel_limited_profile; l < n->comp_level(); l++) { nmethod *inv = lookup_osr_nmethod(n->method(), n->osr_entry_bci(), l, true); if (inv != NULL && inv->is_in_use()) { inv->make_not_entrant(); } } } } void instanceKlass::remove_osr_nmethod(nmethod* n) { // This is a short non-blocking critical region, so the no safepoint check is ok. OsrList_lock->lock_without_safepoint_check(); assert(n->is_osr_method(), "wrong kind of nmethod"); nmethod* last = NULL; nmethod* cur = osr_nmethods_head(); int max_level = CompLevel_none; // Find the max comp level excluding n methodOop m = n->method(); // Search for match while(cur != NULL && cur != n) { if (TieredCompilation) { // Find max level before n max_level = MAX2(max_level, cur->comp_level()); } last = cur; cur = cur->osr_link(); } nmethod* next = NULL; if (cur == n) { next = cur->osr_link(); if (last == NULL) { // Remove first element set_osr_nmethods_head(next); } else { last->set_osr_link(next); } } n->set_osr_link(NULL); if (TieredCompilation) { cur = next; while (cur != NULL) { // Find max level after n max_level = MAX2(max_level, cur->comp_level()); cur = cur->osr_link(); } m->set_highest_osr_comp_level(max_level); } // Remember to unlock again OsrList_lock->unlock(); } nmethod* instanceKlass::lookup_osr_nmethod(const methodOop m, int bci, int comp_level, bool match_level) const { // This is a short non-blocking critical region, so the no safepoint check is ok. OsrList_lock->lock_without_safepoint_check(); nmethod* osr = osr_nmethods_head(); nmethod* best = NULL; while (osr != NULL) { assert(osr->is_osr_method(), "wrong kind of nmethod found in chain"); // There can be a time when a c1 osr method exists but we are waiting // for a c2 version. When c2 completes its osr nmethod we will trash // the c1 version and only be able to find the c2 version. However // while we overflow in the c1 code at back branches we don't want to // try and switch to the same code as we are already running if (osr->method() == m && (bci == InvocationEntryBci || osr->osr_entry_bci() == bci)) { if (match_level) { if (osr->comp_level() == comp_level) { // Found a match - return it. OsrList_lock->unlock(); return osr; } } else { if (best == NULL || (osr->comp_level() > best->comp_level())) { if (osr->comp_level() == CompLevel_highest_tier) { // Found the best possible - return it. OsrList_lock->unlock(); return osr; } best = osr; } } } osr = osr->osr_link(); } OsrList_lock->unlock(); if (best != NULL && best->comp_level() >= comp_level && match_level == false) { return best; } return NULL; } bool instanceKlass::add_member_name(Handle mem_name) { jweak mem_name_wref = JNIHandles::make_weak_global(mem_name); MutexLocker ml(MemberNameTable_lock); DEBUG_ONLY(No_Safepoint_Verifier nsv); // Check if method has been redefined while taking out MemberNameTable_lock, if so // return false. We cannot cache obsolete methods. They will crash when the function // is called! methodOop method = (methodOop)java_lang_invoke_MemberName::vmtarget(mem_name()); if (method->is_obsolete()) { return false; } else if (method->is_old()) { // Replace method with redefined version java_lang_invoke_MemberName::set_vmtarget(mem_name(), method_with_idnum(method->method_idnum())); } if (_member_names == NULL) { _member_names = new (ResourceObj::C_HEAP, mtClass) MemberNameTable(idnum_allocated_count()); } _member_names->add_member_name(mem_name_wref); return true; } // ----------------------------------------------------------------------------------------------------- #ifndef PRODUCT // Printing #define BULLET " - " void FieldPrinter::do_field(fieldDescriptor* fd) { _st->print(BULLET); if (_obj == NULL) { fd->print_on(_st); _st->cr(); } else { fd->print_on_for(_st, _obj); _st->cr(); } } void instanceKlass::oop_print_on(oop obj, outputStream* st) { Klass::oop_print_on(obj, st); if (as_klassOop() == SystemDictionary::String_klass()) { typeArrayOop value = java_lang_String::value(obj); juint offset = java_lang_String::offset(obj); juint length = java_lang_String::length(obj); if (value != NULL && value->is_typeArray() && offset <= (juint) value->length() && offset + length <= (juint) value->length()) { st->print(BULLET"string: "); Handle h_obj(obj); java_lang_String::print(h_obj, st); st->cr(); if (!WizardMode) return; // that is enough } } st->print_cr(BULLET"---- fields (total size %d words):", oop_size(obj)); FieldPrinter print_field(st, obj); do_nonstatic_fields(&print_field); if (as_klassOop() == SystemDictionary::Class_klass()) { st->print(BULLET"signature: "); java_lang_Class::print_signature(obj, st); st->cr(); klassOop mirrored_klass = java_lang_Class::as_klassOop(obj); st->print(BULLET"fake entry for mirror: "); mirrored_klass->print_value_on(st); st->cr(); st->print(BULLET"fake entry resolved_constructor: "); methodOop ctor = java_lang_Class::resolved_constructor(obj); ctor->print_value_on(st); klassOop array_klass = java_lang_Class::array_klass(obj); st->cr(); st->print(BULLET"fake entry for array: "); array_klass->print_value_on(st); st->cr(); st->print_cr(BULLET"fake entry for oop_size: %d", java_lang_Class::oop_size(obj)); st->print_cr(BULLET"fake entry for static_oop_field_count: %d", java_lang_Class::static_oop_field_count(obj)); klassOop real_klass = java_lang_Class::as_klassOop(obj); if (real_klass != NULL && real_klass->klass_part()->oop_is_instance()) { instanceKlass::cast(real_klass)->do_local_static_fields(&print_field); } } else if (as_klassOop() == SystemDictionary::MethodType_klass()) { st->print(BULLET"signature: "); java_lang_invoke_MethodType::print_signature(obj, st); st->cr(); } } #endif //PRODUCT void instanceKlass::oop_print_value_on(oop obj, outputStream* st) { st->print("a "); name()->print_value_on(st); obj->print_address_on(st); if (as_klassOop() == SystemDictionary::String_klass() && java_lang_String::value(obj) != NULL) { ResourceMark rm; int len = java_lang_String::length(obj); int plen = (len < 24 ? len : 12); char* str = java_lang_String::as_utf8_string(obj, 0, plen); st->print(" = \"%s\"", str); if (len > plen) st->print("...[%d]", len); } else if (as_klassOop() == SystemDictionary::Class_klass()) { klassOop k = java_lang_Class::as_klassOop(obj); st->print(" = "); if (k != NULL) { k->print_value_on(st); } else { const char* tname = type2name(java_lang_Class::primitive_type(obj)); st->print("%s", tname ? tname : "type?"); } } else if (as_klassOop() == SystemDictionary::MethodType_klass()) { st->print(" = "); java_lang_invoke_MethodType::print_signature(obj, st); } else if (java_lang_boxing_object::is_instance(obj)) { st->print(" = "); java_lang_boxing_object::print(obj, st); } else if (as_klassOop() == SystemDictionary::LambdaForm_klass()) { oop vmentry = java_lang_invoke_LambdaForm::vmentry(obj); if (vmentry != NULL) { st->print(" => "); vmentry->print_value_on(st); } } else if (as_klassOop() == SystemDictionary::MemberName_klass()) { oop vmtarget = java_lang_invoke_MemberName::vmtarget(obj); if (vmtarget != NULL) { st->print(" = "); vmtarget->print_value_on(st); } else { java_lang_invoke_MemberName::clazz(obj)->print_value_on(st); st->print("."); java_lang_invoke_MemberName::name(obj)->print_value_on(st); } } } const char* instanceKlass::internal_name() const { return external_name(); } // Verification class VerifyFieldClosure: public OopClosure { protected: template void do_oop_work(T* p) { guarantee(Universe::heap()->is_in_closed_subset(p), "should be in heap"); oop obj = oopDesc::load_decode_heap_oop(p); if (!obj->is_oop_or_null()) { tty->print_cr("Failed: " PTR_FORMAT " -> " PTR_FORMAT, p, (address)obj); Universe::print(); guarantee(false, "boom"); } } public: virtual void do_oop(oop* p) { VerifyFieldClosure::do_oop_work(p); } virtual void do_oop(narrowOop* p) { VerifyFieldClosure::do_oop_work(p); } }; void instanceKlass::oop_verify_on(oop obj, outputStream* st) { Klass::oop_verify_on(obj, st); VerifyFieldClosure blk; oop_oop_iterate(obj, &blk); } // JNIid class for jfieldIDs only // Note to reviewers: // These JNI functions are just moved over to column 1 and not changed // in the compressed oops workspace. JNIid::JNIid(klassOop holder, int offset, JNIid* next) { _holder = holder; _offset = offset; _next = next; debug_only(_is_static_field_id = false;) } JNIid* JNIid::find(int offset) { JNIid* current = this; while (current != NULL) { if (current->offset() == offset) return current; current = current->next(); } return NULL; } void JNIid::oops_do(OopClosure* f) { for (JNIid* cur = this; cur != NULL; cur = cur->next()) { f->do_oop(cur->holder_addr()); } } void JNIid::deallocate(JNIid* current) { while (current != NULL) { JNIid* next = current->next(); delete current; current = next; } } void JNIid::verify(klassOop holder) { int first_field_offset = instanceMirrorKlass::offset_of_static_fields(); int end_field_offset; end_field_offset = first_field_offset + (instanceKlass::cast(holder)->static_field_size() * wordSize); JNIid* current = this; while (current != NULL) { guarantee(current->holder() == holder, "Invalid klass in JNIid"); #ifdef ASSERT int o = current->offset(); if (current->is_static_field_id()) { guarantee(o >= first_field_offset && o < end_field_offset, "Invalid static field offset in JNIid"); } #endif current = current->next(); } } #ifdef ASSERT void instanceKlass::set_init_state(ClassState state) { bool good_state = as_klassOop()->is_shared() ? (_init_state <= state) : (_init_state < state); assert(good_state || state == allocated, "illegal state transition"); _init_state = (u1)state; } #endif // RedefineClasses() support for previous versions: // Add an information node that contains weak references to the // interesting parts of the previous version of the_class. // This is also where we clean out any unused weak references. // Note that while we delete nodes from the _previous_versions // array, we never delete the array itself until the klass is // unloaded. The has_been_redefined() query depends on that fact. // void instanceKlass::add_previous_version(instanceKlassHandle ikh, BitMap* emcp_methods, int emcp_method_count) { assert(Thread::current()->is_VM_thread(), "only VMThread can add previous versions"); if (_previous_versions == NULL) { // This is the first previous version so make some space. // Start with 2 elements under the assumption that the class // won't be redefined much. _previous_versions = new (ResourceObj::C_HEAP, mtClass) GrowableArray(2, true); } // RC_TRACE macro has an embedded ResourceMark RC_TRACE(0x00000100, ("adding previous version ref for %s @%d, EMCP_cnt=%d", ikh->external_name(), _previous_versions->length(), emcp_method_count)); constantPoolHandle cp_h(ikh->constants()); jobject cp_ref; if (cp_h->is_shared()) { // a shared ConstantPool requires a regular reference; a weak // reference would be collectible cp_ref = JNIHandles::make_global(cp_h); } else { cp_ref = JNIHandles::make_weak_global(cp_h); } PreviousVersionNode * pv_node = NULL; objArrayOop old_methods = ikh->methods(); if (emcp_method_count == 0) { // non-shared ConstantPool gets a weak reference pv_node = new PreviousVersionNode(cp_ref, !cp_h->is_shared(), NULL); RC_TRACE(0x00000400, ("add: all methods are obsolete; flushing any EMCP weak refs")); } else { int local_count = 0; GrowableArray* method_refs = new (ResourceObj::C_HEAP, mtClass) GrowableArray(emcp_method_count, true); for (int i = 0; i < old_methods->length(); i++) { if (emcp_methods->at(i)) { // this old method is EMCP so save a weak ref methodOop old_method = (methodOop) old_methods->obj_at(i); methodHandle old_method_h(old_method); jweak method_ref = JNIHandles::make_weak_global(old_method_h); method_refs->append(method_ref); if (++local_count >= emcp_method_count) { // no more EMCP methods so bail out now break; } } } // non-shared ConstantPool gets a weak reference pv_node = new PreviousVersionNode(cp_ref, !cp_h->is_shared(), method_refs); } _previous_versions->append(pv_node); // Using weak references allows the interesting parts of previous // classes to be GC'ed when they are no longer needed. Since the // caller is the VMThread and we are at a safepoint, this is a good // time to clear out unused weak references. RC_TRACE(0x00000400, ("add: previous version length=%d", _previous_versions->length())); // skip the last entry since we just added it for (int i = _previous_versions->length() - 2; i >= 0; i--) { // check the previous versions array for a GC'ed weak refs pv_node = _previous_versions->at(i); cp_ref = pv_node->prev_constant_pool(); assert(cp_ref != NULL, "cp ref was unexpectedly cleared"); if (cp_ref == NULL) { delete pv_node; _previous_versions->remove_at(i); // Since we are traversing the array backwards, we don't have to // do anything special with the index. continue; // robustness } constantPoolOop cp = (constantPoolOop)JNIHandles::resolve(cp_ref); if (cp == NULL) { // this entry has been GC'ed so remove it delete pv_node; _previous_versions->remove_at(i); // Since we are traversing the array backwards, we don't have to // do anything special with the index. continue; } else { RC_TRACE(0x00000400, ("add: previous version @%d is alive", i)); } GrowableArray* method_refs = pv_node->prev_EMCP_methods(); if (method_refs != NULL) { RC_TRACE(0x00000400, ("add: previous methods length=%d", method_refs->length())); for (int j = method_refs->length() - 1; j >= 0; j--) { jweak method_ref = method_refs->at(j); assert(method_ref != NULL, "weak method ref was unexpectedly cleared"); if (method_ref == NULL) { method_refs->remove_at(j); // Since we are traversing the array backwards, we don't have to // do anything special with the index. continue; // robustness } methodOop method = (methodOop)JNIHandles::resolve(method_ref); if (method == NULL || emcp_method_count == 0) { // This method entry has been GC'ed or the current // RedefineClasses() call has made all methods obsolete // so remove it. JNIHandles::destroy_weak_global(method_ref); method_refs->remove_at(j); } else { // RC_TRACE macro has an embedded ResourceMark RC_TRACE(0x00000400, ("add: %s(%s): previous method @%d in version @%d is alive", method->name()->as_C_string(), method->signature()->as_C_string(), j, i)); } } } } int obsolete_method_count = old_methods->length() - emcp_method_count; if (emcp_method_count != 0 && obsolete_method_count != 0 && _previous_versions->length() > 1) { // We have a mix of obsolete and EMCP methods. If there is more // than the previous version that we just added, then we have to // clear out any matching EMCP method entries the hard way. int local_count = 0; for (int i = 0; i < old_methods->length(); i++) { if (!emcp_methods->at(i)) { // only obsolete methods are interesting methodOop old_method = (methodOop) old_methods->obj_at(i); Symbol* m_name = old_method->name(); Symbol* m_signature = old_method->signature(); // skip the last entry since we just added it for (int j = _previous_versions->length() - 2; j >= 0; j--) { // check the previous versions array for a GC'ed weak refs pv_node = _previous_versions->at(j); cp_ref = pv_node->prev_constant_pool(); assert(cp_ref != NULL, "cp ref was unexpectedly cleared"); if (cp_ref == NULL) { delete pv_node; _previous_versions->remove_at(j); // Since we are traversing the array backwards, we don't have to // do anything special with the index. continue; // robustness } constantPoolOop cp = (constantPoolOop)JNIHandles::resolve(cp_ref); if (cp == NULL) { // this entry has been GC'ed so remove it delete pv_node; _previous_versions->remove_at(j); // Since we are traversing the array backwards, we don't have to // do anything special with the index. continue; } GrowableArray* method_refs = pv_node->prev_EMCP_methods(); if (method_refs == NULL) { // We have run into a PreviousVersion generation where // all methods were made obsolete during that generation's // RedefineClasses() operation. At the time of that // operation, all EMCP methods were flushed so we don't // have to go back any further. // // A NULL method_refs is different than an empty method_refs. // We cannot infer any optimizations about older generations // from an empty method_refs for the current generation. break; } for (int k = method_refs->length() - 1; k >= 0; k--) { jweak method_ref = method_refs->at(k); assert(method_ref != NULL, "weak method ref was unexpectedly cleared"); if (method_ref == NULL) { method_refs->remove_at(k); // Since we are traversing the array backwards, we don't // have to do anything special with the index. continue; // robustness } methodOop method = (methodOop)JNIHandles::resolve(method_ref); if (method == NULL) { // this method entry has been GC'ed so skip it JNIHandles::destroy_weak_global(method_ref); method_refs->remove_at(k); continue; } if (method->name() == m_name && method->signature() == m_signature) { // The current RedefineClasses() call has made all EMCP // versions of this method obsolete so mark it as obsolete // and remove the weak ref. RC_TRACE(0x00000400, ("add: %s(%s): flush obsolete method @%d in version @%d", m_name->as_C_string(), m_signature->as_C_string(), k, j)); method->set_is_obsolete(); JNIHandles::destroy_weak_global(method_ref); method_refs->remove_at(k); break; } } // The previous loop may not find a matching EMCP method, but // that doesn't mean that we can optimize and not go any // further back in the PreviousVersion generations. The EMCP // method for this generation could have already been GC'ed, // but there still may be an older EMCP method that has not // been GC'ed. } if (++local_count >= obsolete_method_count) { // no more obsolete methods so bail out now break; } } } } } // end add_previous_version() // Determine if instanceKlass has a previous version. bool instanceKlass::has_previous_version() const { if (_previous_versions == NULL) { // no previous versions array so answer is easy return false; } for (int i = _previous_versions->length() - 1; i >= 0; i--) { // Check the previous versions array for an info node that hasn't // been GC'ed PreviousVersionNode * pv_node = _previous_versions->at(i); jobject cp_ref = pv_node->prev_constant_pool(); assert(cp_ref != NULL, "cp reference was unexpectedly cleared"); if (cp_ref == NULL) { continue; // robustness } constantPoolOop cp = (constantPoolOop)JNIHandles::resolve(cp_ref); if (cp != NULL) { // we have at least one previous version return true; } // We don't have to check the method refs. If the constant pool has // been GC'ed then so have the methods. } // all of the underlying nodes' info has been GC'ed return false; } // end has_previous_version() methodOop instanceKlass::method_with_idnum(int idnum) { methodOop m = NULL; if (idnum < methods()->length()) { m = (methodOop) methods()->obj_at(idnum); } if (m == NULL || m->method_idnum() != idnum) { for (int index = 0; index < methods()->length(); ++index) { m = (methodOop) methods()->obj_at(index); if (m->method_idnum() == idnum) { return m; } } } return m; } // Set the annotation at 'idnum' to 'anno'. // We don't want to create or extend the array if 'anno' is NULL, since that is the // default value. However, if the array exists and is long enough, we must set NULL values. void instanceKlass::set_methods_annotations_of(int idnum, typeArrayOop anno, objArrayOop* md_p) { objArrayOop md = *md_p; if (md != NULL && md->length() > idnum) { md->obj_at_put(idnum, anno); } else if (anno != NULL) { // create the array int length = MAX2(idnum+1, (int)_idnum_allocated_count); md = oopFactory::new_system_objArray(length, Thread::current()); if (*md_p != NULL) { // copy the existing entries for (int index = 0; index < (*md_p)->length(); index++) { md->obj_at_put(index, (*md_p)->obj_at(index)); } } set_annotations(md, md_p); md->obj_at_put(idnum, anno); } // if no array and idnum isn't included there is nothing to do } // Construct a PreviousVersionNode entry for the array hung off // the instanceKlass. PreviousVersionNode::PreviousVersionNode(jobject prev_constant_pool, bool prev_cp_is_weak, GrowableArray* prev_EMCP_methods) { _prev_constant_pool = prev_constant_pool; _prev_cp_is_weak = prev_cp_is_weak; _prev_EMCP_methods = prev_EMCP_methods; } // Destroy a PreviousVersionNode PreviousVersionNode::~PreviousVersionNode() { if (_prev_constant_pool != NULL) { if (_prev_cp_is_weak) { JNIHandles::destroy_weak_global(_prev_constant_pool); } else { JNIHandles::destroy_global(_prev_constant_pool); } } if (_prev_EMCP_methods != NULL) { for (int i = _prev_EMCP_methods->length() - 1; i >= 0; i--) { jweak method_ref = _prev_EMCP_methods->at(i); if (method_ref != NULL) { JNIHandles::destroy_weak_global(method_ref); } } delete _prev_EMCP_methods; } } // Construct a PreviousVersionInfo entry PreviousVersionInfo::PreviousVersionInfo(PreviousVersionNode *pv_node) { _prev_constant_pool_handle = constantPoolHandle(); // NULL handle _prev_EMCP_method_handles = NULL; jobject cp_ref = pv_node->prev_constant_pool(); assert(cp_ref != NULL, "constant pool ref was unexpectedly cleared"); if (cp_ref == NULL) { return; // robustness } constantPoolOop cp = (constantPoolOop)JNIHandles::resolve(cp_ref); if (cp == NULL) { // Weak reference has been GC'ed. Since the constant pool has been // GC'ed, the methods have also been GC'ed. return; } // make the constantPoolOop safe to return _prev_constant_pool_handle = constantPoolHandle(cp); GrowableArray* method_refs = pv_node->prev_EMCP_methods(); if (method_refs == NULL) { // the instanceKlass did not have any EMCP methods return; } _prev_EMCP_method_handles = new GrowableArray(10); int n_methods = method_refs->length(); for (int i = 0; i < n_methods; i++) { jweak method_ref = method_refs->at(i); assert(method_ref != NULL, "weak method ref was unexpectedly cleared"); if (method_ref == NULL) { continue; // robustness } methodOop method = (methodOop)JNIHandles::resolve(method_ref); if (method == NULL) { // this entry has been GC'ed so skip it continue; } // make the methodOop safe to return _prev_EMCP_method_handles->append(methodHandle(method)); } } // Destroy a PreviousVersionInfo PreviousVersionInfo::~PreviousVersionInfo() { // Since _prev_EMCP_method_handles is not C-heap allocated, we // don't have to delete it. } // Construct a helper for walking the previous versions array PreviousVersionWalker::PreviousVersionWalker(instanceKlass *ik) { _previous_versions = ik->previous_versions(); _current_index = 0; // _hm needs no initialization _current_p = NULL; } // Destroy a PreviousVersionWalker PreviousVersionWalker::~PreviousVersionWalker() { // Delete the current info just in case the caller didn't walk to // the end of the previous versions list. No harm if _current_p is // already NULL. delete _current_p; // When _hm is destroyed, all the Handles returned in // PreviousVersionInfo objects will be destroyed. // Also, after this destructor is finished it will be // safe to delete the GrowableArray allocated in the // PreviousVersionInfo objects. } // Return the interesting information for the next previous version // of the klass. Returns NULL if there are no more previous versions. PreviousVersionInfo* PreviousVersionWalker::next_previous_version() { if (_previous_versions == NULL) { // no previous versions so nothing to return return NULL; } delete _current_p; // cleanup the previous info for the caller _current_p = NULL; // reset to NULL so we don't delete same object twice int length = _previous_versions->length(); while (_current_index < length) { PreviousVersionNode * pv_node = _previous_versions->at(_current_index++); PreviousVersionInfo * pv_info = new (ResourceObj::C_HEAP, mtClass) PreviousVersionInfo(pv_node); constantPoolHandle cp_h = pv_info->prev_constant_pool_handle(); if (cp_h.is_null()) { delete pv_info; // The underlying node's info has been GC'ed so try the next one. // We don't have to check the methods. If the constant pool has // GC'ed then so have the methods. continue; } // Found a node with non GC'ed info so return it. The caller will // need to delete pv_info when they are done with it. _current_p = pv_info; return pv_info; } // all of the underlying nodes' info has been GC'ed return NULL; } // end next_previous_version()