/* * Copyright (c) 1997, 2012, 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/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "gc_implementation/shared/markSweep.inline.hpp" #include "memory/gcLocker.hpp" #include "memory/resourceArea.hpp" #include "memory/universe.inline.hpp" #include "oops/instanceKlass.hpp" #include "oops/klassVtable.hpp" #include "oops/method.hpp" #include "oops/objArrayOop.hpp" #include "oops/oop.inline.hpp" #include "prims/jvmtiRedefineClassesTrace.hpp" #include "runtime/arguments.hpp" #include "runtime/handles.inline.hpp" #include "utilities/copy.hpp" inline InstanceKlass* klassVtable::ik() const { Klass* k = _klass(); assert(k->oop_is_instance(), "not an InstanceKlass"); return (InstanceKlass*)k; } // this function computes the vtable size (including the size needed for miranda // methods) and the number of miranda methods in this class // Note on Miranda methods: Let's say there is a class C that implements // interface I. Let's say there is a method m in I that neither C nor any // of its super classes implement (i.e there is no method of any access, with // the same name and signature as m), then m is a Miranda method which is // entered as a public abstract method in C's vtable. From then on it should // treated as any other public method in C for method over-ride purposes. void klassVtable::compute_vtable_size_and_num_mirandas( int* vtable_length_ret, int* num_new_mirandas, GrowableArray* all_mirandas, Klass* super, Array* methods, AccessFlags class_flags, Handle classloader, Symbol* classname, Array* local_interfaces, TRAPS) { No_Safepoint_Verifier nsv; // set up default result values int vtable_length = 0; // start off with super's vtable length InstanceKlass* sk = (InstanceKlass*)super; vtable_length = super == NULL ? 0 : sk->vtable_length(); // go thru each method in the methods table to see if it needs a new entry int len = methods->length(); for (int i = 0; i < len; i++) { assert(methods->at(i)->is_method(), "must be a Method*"); methodHandle mh(THREAD, methods->at(i)); if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) { vtable_length += vtableEntry::size(); // we need a new entry } } GrowableArray new_mirandas(20); // compute the number of mirandas methods that must be added to the end get_mirandas(&new_mirandas, all_mirandas, super, methods, local_interfaces); *num_new_mirandas = new_mirandas.length(); vtable_length += *num_new_mirandas * vtableEntry::size(); if (Universe::is_bootstrapping() && vtable_length == 0) { // array classes don't have their superclass set correctly during // bootstrapping vtable_length = Universe::base_vtable_size(); } if (super == NULL && !Universe::is_bootstrapping() && vtable_length != Universe::base_vtable_size()) { // Someone is attempting to redefine java.lang.Object incorrectly. The // only way this should happen is from // SystemDictionary::resolve_from_stream(), which will detect this later // and throw a security exception. So don't assert here to let // the exception occur. vtable_length = Universe::base_vtable_size(); } assert(super != NULL || vtable_length == Universe::base_vtable_size(), "bad vtable size for class Object"); assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); *vtable_length_ret = vtable_length; } int klassVtable::index_of(Method* m, int len) const { assert(m->vtable_index() >= 0, "do not ask this of non-vtable methods"); return m->vtable_index(); } int klassVtable::initialize_from_super(KlassHandle super) { if (super.is_null()) { return 0; } else { // copy methods from superKlass // can't inherit from array class, so must be InstanceKlass assert(super->oop_is_instance(), "must be instance klass"); InstanceKlass* sk = (InstanceKlass*)super(); klassVtable* superVtable = sk->vtable(); assert(superVtable->length() <= _length, "vtable too short"); #ifdef ASSERT superVtable->verify(tty, true); #endif superVtable->copy_vtable_to(table()); #ifndef PRODUCT if (PrintVtables && Verbose) { ResourceMark rm; tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length); } #endif return superVtable->length(); } } // Revised lookup semantics introduced 1.3 (Kestral beta) void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { // Note: Arrays can have intermediate array supers. Use java_super to skip them. KlassHandle super (THREAD, klass()->java_super()); int nofNewEntries = 0; if (PrintVtables && !klass()->oop_is_array()) { ResourceMark rm(THREAD); tty->print_cr("Initializing: %s", _klass->name()->as_C_string()); } #ifdef ASSERT oop* end_of_obj = (oop*)_klass() + _klass()->size(); oop* end_of_vtable = (oop*)&table()[_length]; assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); #endif if (Universe::is_bootstrapping()) { // just clear everything for (int i = 0; i < _length; i++) table()[i].clear(); return; } int super_vtable_len = initialize_from_super(super); if (klass()->oop_is_array()) { assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); } else { assert(_klass->oop_is_instance(), "must be InstanceKlass"); Array* methods = ik()->methods(); int len = methods->length(); int initialized = super_vtable_len; // update_inherited_vtable can stop for gc - ensure using handles for (int i = 0; i < len; i++) { HandleMark hm(THREAD); assert(methods->at(i)->is_method(), "must be a Method*"); methodHandle mh(THREAD, methods->at(i)); bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, checkconstraints, CHECK); if (needs_new_entry) { put_method_at(mh(), initialized); mh()->set_vtable_index(initialized); // set primary vtable index initialized++; } } // add miranda methods; it will also update the value of initialized fill_in_mirandas(&initialized); // In class hierarchies where the accessibility is not increasing (i.e., going from private -> // package_private -> publicprotected), the vtable might actually be smaller than our initial // calculation. assert(initialized <= _length, "vtable initialization failed"); for(;initialized < _length; initialized++) { put_method_at(NULL, initialized); } NOT_PRODUCT(verify(tty, true)); } } // Called for cases where a method does not override its superclass' vtable entry // For bytecodes not produced by javac together it is possible that a method does not override // the superclass's method, but might indirectly override a super-super class's vtable entry // If none found, return a null superk, else return the superk of the method this does override InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { InstanceKlass* superk = initialsuper; while (superk != NULL && superk->super() != NULL) { InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); klassVtable* ssVtable = supersuperklass->vtable(); if (vtable_index < ssVtable->length()) { Method* super_method = ssVtable->method_at(vtable_index); #ifndef PRODUCT Symbol* name= target_method()->name(); Symbol* signature = target_method()->signature(); assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); #endif if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { #ifndef PRODUCT if (PrintVtables && Verbose) { ResourceMark rm(THREAD); tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ", supersuperklass->internal_name(), _klass->internal_name(), (target_method() != NULL) ? target_method()->name()->as_C_string() : "", vtable_index); super_method->access_flags().print_on(tty); tty->print("overriders flags: "); target_method->access_flags().print_on(tty); tty->cr(); } #endif /*PRODUCT*/ break; // return found superk } } else { // super class has no vtable entry here, stop transitive search superk = (InstanceKlass*)NULL; break; } // if no override found yet, continue to search up superk = InstanceKlass::cast(superk->super()); } return superk; } // Methods that are "effectively" final don't need vtable entries. bool method_is_effectively_final( AccessFlags klass_flags, methodHandle target) { return target->is_final() || klass_flags.is_final() && !target->is_overpass(); } // Update child's copy of super vtable for overrides // OR return true if a new vtable entry is required // Only called for InstanceKlass's, i.e. not for arrays // If that changed, could not use _klass as handle for klass bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, int super_vtable_len, bool checkconstraints, TRAPS) { ResourceMark rm; bool allocate_new = true; assert(klass->oop_is_instance(), "must be InstanceKlass"); // Initialize the method's vtable index to "nonvirtual". // If we allocate a vtable entry, we will update it to a non-negative number. target_method()->set_vtable_index(Method::nonvirtual_vtable_index); // Static and methods are never in if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { return false; } if (method_is_effectively_final(klass->access_flags(), target_method)) { // a final method never needs a new entry; final methods can be statically // resolved and they have to be present in the vtable only if they override // a super's method, in which case they re-use its entry allocate_new = false; } // we need a new entry if there is no superclass if (klass->super() == NULL) { return allocate_new; } // private methods always have a new entry in the vtable // specification interpretation since classic has // private methods not overriding if (target_method()->is_private()) { return allocate_new; } // search through the vtable and update overridden entries // Since check_signature_loaders acquires SystemDictionary_lock // which can block for gc, once we are in this loop, use handles // For classfiles built with >= jdk7, we now look for transitive overrides Symbol* name = target_method()->name(); Symbol* signature = target_method()->signature(); Handle target_loader(THREAD, _klass()->class_loader()); Symbol* target_classname = _klass->name(); for(int i = 0; i < super_vtable_len; i++) { Method* super_method = method_at(i); // Check if method name matches if (super_method->name() == name && super_method->signature() == signature) { // get super_klass for method_holder for the found method InstanceKlass* super_klass = InstanceKlass::cast(super_method->method_holder()); if ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) && ((super_klass = find_transitive_override(super_klass, target_method, i, target_loader, target_classname, THREAD)) != (InstanceKlass*)NULL))) { // overriding, so no new entry allocate_new = false; if (checkconstraints) { // Override vtable entry if passes loader constraint check // if loader constraint checking requested // No need to visit his super, since he and his super // have already made any needed loader constraints. // Since loader constraints are transitive, it is enough // to link to the first super, and we get all the others. Handle super_loader(THREAD, super_klass->class_loader()); if (target_loader() != super_loader()) { ResourceMark rm(THREAD); char* failed_type_name = SystemDictionary::check_signature_loaders(signature, target_loader, super_loader, true, CHECK_(false)); if (failed_type_name != NULL) { const char* msg = "loader constraint violation: when resolving " "overridden method \"%s\" the class loader (instance" " of %s) of the current class, %s, and its superclass loader " "(instance of %s), have different Class objects for the type " "%s used in the signature"; char* sig = target_method()->name_and_sig_as_C_string(); const char* loader1 = SystemDictionary::loader_name(target_loader()); char* current = _klass->name()->as_C_string(); const char* loader2 = SystemDictionary::loader_name(super_loader()); size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + strlen(current) + strlen(loader2) + strlen(failed_type_name); char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, failed_type_name); THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); } } } put_method_at(target_method(), i); target_method()->set_vtable_index(i); #ifndef PRODUCT if (PrintVtables && Verbose) { tty->print("overriding with %s::%s index %d, original flags: ", _klass->internal_name(), (target_method() != NULL) ? target_method()->name()->as_C_string() : "", i); super_method->access_flags().print_on(tty); tty->print("overriders flags: "); target_method->access_flags().print_on(tty); tty->cr(); } #endif /*PRODUCT*/ } else { // allocate_new = true; default. We might override one entry, // but not override another. Once we override one, not need new #ifndef PRODUCT if (PrintVtables && Verbose) { tty->print("NOT overriding with %s::%s index %d, original flags: ", _klass->internal_name(), (target_method() != NULL) ? target_method()->name()->as_C_string() : "", i); super_method->access_flags().print_on(tty); tty->print("overriders flags: "); target_method->access_flags().print_on(tty); tty->cr(); } #endif /*PRODUCT*/ } } } return allocate_new; } void klassVtable::put_method_at(Method* m, int index) { #ifndef PRODUCT if (PrintVtables && Verbose) { ResourceMark rm; tty->print_cr("adding %s::%s at index %d", _klass->internal_name(), (m != NULL) ? m->name()->as_C_string() : "", index); } #endif table()[index].set(m); } // Find out if a method "m" with superclass "super", loader "classloader" and // name "classname" needs a new vtable entry. Let P be a class package defined // by "classloader" and "classname". // NOTE: The logic used here is very similar to the one used for computing // the vtables indices for a method. We cannot directly use that function because, // we allocate the InstanceKlass at load time, and that requires that the // superclass has been loaded. // However, the vtable entries are filled in at link time, and therefore // the superclass' vtable may not yet have been filled in. bool klassVtable::needs_new_vtable_entry(methodHandle target_method, Klass* super, Handle classloader, Symbol* classname, AccessFlags class_flags, TRAPS) { if (method_is_effectively_final(class_flags, target_method) || // a final method never needs a new entry; final methods can be statically // resolved and they have to be present in the vtable only if they override // a super's method, in which case they re-use its entry (target_method()->is_static()) || // static methods don't need to be in vtable (target_method()->name() == vmSymbols::object_initializer_name()) // is never called dynamically-bound ) { return false; } // we need a new entry if there is no superclass if (super == NULL) { return true; } // private methods always have a new entry in the vtable // specification interpretation since classic has // private methods not overriding if (target_method()->is_private()) { return true; } // search through the super class hierarchy to see if we need // a new entry ResourceMark rm; Symbol* name = target_method()->name(); Symbol* signature = target_method()->signature(); Klass* k = super; Method* super_method = NULL; InstanceKlass *holder = NULL; Method* recheck_method = NULL; while (k != NULL) { // lookup through the hierarchy for a method with matching name and sign. super_method = InstanceKlass::cast(k)->lookup_method(name, signature); if (super_method == NULL) { break; // we still have to search for a matching miranda method } // get the class holding the matching method // make sure you use that class for is_override InstanceKlass* superk = InstanceKlass::cast(super_method->method_holder()); // we want only instance method matches // pretend private methods are not in the super vtable // since we do override around them: e.g. a.m pub/b.m private/c.m pub, // ignore private, c.m pub does override a.m pub // For classes that were not javac'd together, we also do transitive overriding around // methods that have less accessibility if ((!super_method->is_static()) && (!super_method->is_private())) { if (superk->is_override(super_method, classloader, classname, THREAD)) { return false; // else keep looking for transitive overrides } } // Start with lookup result and continue to search up k = superk->super(); // haven't found an override match yet; continue to look } // if the target method is public or protected it may have a matching // miranda method in the super, whose entry it should re-use. // Actually, to handle cases that javac would not generate, we need // this check for all access permissions. InstanceKlass *sk = InstanceKlass::cast(super); if (sk->has_miranda_methods()) { if (sk->lookup_method_in_all_interfaces(name, signature) != NULL) { return false; // found a matching miranda; we do not need a new entry } } return true; // found no match; we need a new entry } // Support for miranda methods // get the vtable index of a miranda method with matching "name" and "signature" int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { // search from the bottom, might be faster for (int i = (length() - 1); i >= 0; i--) { Method* m = table()[i].method(); if (is_miranda_entry_at(i) && m->name() == name && m->signature() == signature) { return i; } } return Method::invalid_vtable_index; } // check if an entry is miranda bool klassVtable::is_miranda_entry_at(int i) { Method* m = method_at(i); Klass* method_holder = m->method_holder(); InstanceKlass *mhk = InstanceKlass::cast(method_holder); // miranda methods are interface methods in a class's vtable if (mhk->is_interface()) { assert(m->is_public(), "should be public"); assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); assert(is_miranda(m, ik()->methods(), ik()->super()), "should be a miranda_method"); return true; } return false; } // check if a method is a miranda method, given a class's methods table and it's super // the caller must make sure that the method belongs to an interface implemented by the class bool klassVtable::is_miranda(Method* m, Array* class_methods, Klass* super) { Symbol* name = m->name(); Symbol* signature = m->signature(); if (InstanceKlass::find_method(class_methods, name, signature) == NULL) { // did not find it in the method table of the current class if (super == NULL) { // super doesn't exist return true; } Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature); if (mo == NULL || mo->access_flags().is_private() ) { // super class hierarchy does not implement it or protection is different return true; } } return false; } void klassVtable::add_new_mirandas_to_lists( GrowableArray* new_mirandas, GrowableArray* all_mirandas, Array* current_interface_methods, Array* class_methods, Klass* super) { // iterate thru the current interface's method to see if it a miranda int num_methods = current_interface_methods->length(); for (int i = 0; i < num_methods; i++) { Method* im = current_interface_methods->at(i); bool is_duplicate = false; int num_of_current_mirandas = new_mirandas->length(); // check for duplicate mirandas in different interfaces we implement for (int j = 0; j < num_of_current_mirandas; j++) { Method* miranda = new_mirandas->at(j); if ((im->name() == miranda->name()) && (im->signature() == miranda->signature())) { is_duplicate = true; break; } } if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable if (is_miranda(im, class_methods, super)) { // is it a miranda at all? InstanceKlass *sk = InstanceKlass::cast(super); // check if it is a duplicate of a super's miranda if (sk->lookup_method_in_all_interfaces(im->name(), im->signature()) == NULL) { new_mirandas->append(im); } if (all_mirandas != NULL) { all_mirandas->append(im); } } } } } void klassVtable::get_mirandas(GrowableArray* new_mirandas, GrowableArray* all_mirandas, Klass* super, Array* class_methods, Array* local_interfaces) { assert((new_mirandas->length() == 0) , "current mirandas must be 0"); // iterate thru the local interfaces looking for a miranda int num_local_ifs = local_interfaces->length(); for (int i = 0; i < num_local_ifs; i++) { InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); add_new_mirandas_to_lists(new_mirandas, all_mirandas, ik->methods(), class_methods, super); // iterate thru each local's super interfaces Array* super_ifs = ik->transitive_interfaces(); int num_super_ifs = super_ifs->length(); for (int j = 0; j < num_super_ifs; j++) { InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); add_new_mirandas_to_lists(new_mirandas, all_mirandas, sik->methods(), class_methods, super); } } } // fill in mirandas void klassVtable::fill_in_mirandas(int* initialized) { GrowableArray mirandas(20); get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), ik()->local_interfaces()); for (int i = 0; i < mirandas.length(); i++) { put_method_at(mirandas.at(i), *initialized); ++(*initialized); } } void klassVtable::copy_vtable_to(vtableEntry* start) { Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); } void klassVtable::adjust_method_entries(Method** old_methods, Method** new_methods, int methods_length, bool * trace_name_printed) { // search the vtable for uses of either obsolete or EMCP methods for (int j = 0; j < methods_length; j++) { Method* old_method = old_methods[j]; Method* new_method = new_methods[j]; // In the vast majority of cases we could get the vtable index // by using: old_method->vtable_index() // However, there are rare cases, eg. sun.awt.X11.XDecoratedPeer.getX() // in sun.awt.X11.XFramePeer where methods occur more than once in the // vtable, so, alas, we must do an exhaustive search. for (int index = 0; index < length(); index++) { if (unchecked_method_at(index) == old_method) { put_method_at(new_method, index); if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { if (!(*trace_name_printed)) { // RC_TRACE_MESG macro has an embedded ResourceMark RC_TRACE_MESG(("adjust: name=%s", Klass::cast(old_method->method_holder())->external_name())); *trace_name_printed = true; } // RC_TRACE macro has an embedded ResourceMark RC_TRACE(0x00100000, ("vtable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string())); } } } } } // CDS/RedefineClasses support - clear vtables so they can be reinitialized void klassVtable::clear_vtable() { for (int i = 0; i < _length; i++) table()[i].clear(); } bool klassVtable::is_initialized() { return _length == 0 || table()[0].method() != NULL; } //----------------------------------------------------------------------------------------- // Itable code // Initialize a itableMethodEntry void itableMethodEntry::initialize(Method* m) { if (m == NULL) return; _method = m; } klassItable::klassItable(instanceKlassHandle klass) { _klass = klass; if (klass->itable_length() > 0) { itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized // First offset entry points to the first method_entry intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset()); intptr_t* end = klass->end_of_itable(); _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass(); _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); _size_method_table = (end - method_entry) / itableMethodEntry::size(); assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); return; } } // The length of the itable was either zero, or it has not yet been initialized. _table_offset = 0; _size_offset_table = 0; _size_method_table = 0; } static int initialize_count = 0; // Initialization void klassItable::initialize_itable(bool checkconstraints, TRAPS) { // Cannot be setup doing bootstrapping, interfaces don't have // itables, and klass with only ones entry have empty itables if (Universe::is_bootstrapping() || _klass->is_interface() || _klass->itable_length() == itableOffsetEntry::size()) return; // There's alway an extra itable entry so we can null-terminate it. guarantee(size_offset_table() >= 1, "too small"); int num_interfaces = size_offset_table() - 1; if (num_interfaces > 0) { if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count, _klass->name()->as_C_string()); // Iterate through all interfaces int i; for(i = 0; i < num_interfaces; i++) { itableOffsetEntry* ioe = offset_entry(i); HandleMark hm(THREAD); KlassHandle interf_h (THREAD, ioe->interface_klass()); assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable"); initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK); } } // Check that the last entry is empty itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); } void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) { Array* methods = InstanceKlass::cast(interf_h())->methods(); int nof_methods = methods->length(); HandleMark hm; KlassHandle klass = _klass; assert(nof_methods > 0, "at least one method must exist for interface to be in vtable"); Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader()); int ime_num = 0; // Skip first Method* if it is a class initializer int i = methods->at(0)->is_static_initializer() ? 1 : 0; // m, method_name, method_signature, klass reset each loop so they // don't need preserving across check_signature_loaders call // methods needs a handle in case of gc from check_signature_loaders for(; i < nof_methods; i++) { Method* m = methods->at(i); Symbol* method_name = m->name(); Symbol* method_signature = m->signature(); // This is same code as in Linkresolver::lookup_instance_method_in_klasses Method* target = klass->uncached_lookup_method(method_name, method_signature); while (target != NULL && target->is_static()) { // continue with recursive lookup through the superclass Klass* super = Klass::cast(target->method_holder())->super(); target = (super == NULL) ? (Method*)NULL : Klass::cast(super)->uncached_lookup_method(method_name, method_signature); } if (target == NULL || !target->is_public() || target->is_abstract()) { // Entry do not resolve. Leave it empty } else { // Entry did resolve, check loader constraints before initializing // if checkconstraints requested methodHandle target_h (THREAD, target); // preserve across gc if (checkconstraints) { Handle method_holder_loader (THREAD, InstanceKlass::cast(target->method_holder())->class_loader()); if (method_holder_loader() != interface_loader()) { ResourceMark rm(THREAD); char* failed_type_name = SystemDictionary::check_signature_loaders(method_signature, method_holder_loader, interface_loader, true, CHECK); if (failed_type_name != NULL) { const char* msg = "loader constraint violation in interface " "itable initialization: when resolving method \"%s\" the class" " loader (instance of %s) of the current class, %s, " "and the class loader (instance of %s) for interface " "%s have different Class objects for the type %s " "used in the signature"; char* sig = target_h()->name_and_sig_as_C_string(); const char* loader1 = SystemDictionary::loader_name(method_holder_loader()); char* current = klass->name()->as_C_string(); const char* loader2 = SystemDictionary::loader_name(interface_loader()); char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string(); size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + strlen(current) + strlen(loader2) + strlen(iface) + strlen(failed_type_name); char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, iface, failed_type_name); THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); } } } // ime may have moved during GC so recalculate address itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target_h()); } // Progress to next entry ime_num++; } } // Update entry for specific Method* void klassItable::initialize_with_method(Method* m) { itableMethodEntry* ime = method_entry(0); for(int i = 0; i < _size_method_table; i++) { if (ime->method() == m) { ime->initialize(m); } ime++; } } void klassItable::adjust_method_entries(Method** old_methods, Method** new_methods, int methods_length, bool * trace_name_printed) { // search the itable for uses of either obsolete or EMCP methods for (int j = 0; j < methods_length; j++) { Method* old_method = old_methods[j]; Method* new_method = new_methods[j]; itableMethodEntry* ime = method_entry(0); // The itable can describe more than one interface and the same // method signature can be specified by more than one interface. // This means we have to do an exhaustive search to find all the // old_method references. for (int i = 0; i < _size_method_table; i++) { if (ime->method() == old_method) { ime->initialize(new_method); if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { if (!(*trace_name_printed)) { // RC_TRACE_MESG macro has an embedded ResourceMark RC_TRACE_MESG(("adjust: name=%s", Klass::cast(old_method->method_holder())->external_name())); *trace_name_printed = true; } // RC_TRACE macro has an embedded ResourceMark RC_TRACE(0x00200000, ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string())); } // Cannot break because there might be another entry for this method } ime++; } } } // Setup class InterfaceVisiterClosure : public StackObj { public: virtual void doit(Klass* intf, int method_count) = 0; }; // Visit all interfaces with at-least one method (excluding ) void visit_all_interfaces(Array* transitive_intf, InterfaceVisiterClosure *blk) { // Handle array argument for(int i = 0; i < transitive_intf->length(); i++) { Klass* intf = transitive_intf->at(i); assert(Klass::cast(intf)->is_interface(), "sanity check"); // Find no. of methods excluding a int method_count = InstanceKlass::cast(intf)->methods()->length(); if (method_count > 0) { Method* m = InstanceKlass::cast(intf)->methods()->at(0); assert(m != NULL && m->is_method(), "sanity check"); if (m->name() == vmSymbols::object_initializer_name()) { method_count--; } } // Only count interfaces with at least one method if (method_count > 0) { blk->doit(intf, method_count); } } } class CountInterfacesClosure : public InterfaceVisiterClosure { private: int _nof_methods; int _nof_interfaces; public: CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } int nof_methods() const { return _nof_methods; } int nof_interfaces() const { return _nof_interfaces; } void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } }; class SetupItableClosure : public InterfaceVisiterClosure { private: itableOffsetEntry* _offset_entry; itableMethodEntry* _method_entry; address _klass_begin; public: SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { _klass_begin = klass_begin; _offset_entry = offset_entry; _method_entry = method_entry; } itableMethodEntry* method_entry() const { return _method_entry; } void doit(Klass* intf, int method_count) { int offset = ((address)_method_entry) - _klass_begin; _offset_entry->initialize(intf, offset); _offset_entry++; _method_entry += method_count; } }; int klassItable::compute_itable_size(Array* transitive_interfaces) { // Count no of interfaces and total number of interface methods CountInterfacesClosure cic; visit_all_interfaces(transitive_interfaces, &cic); // There's alway an extra itable entry so we can null-terminate it. int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); // Statistics update_stats(itable_size * HeapWordSize); return itable_size; } // Fill out offset table and interface klasses into the itable space void klassItable::setup_itable_offset_table(instanceKlassHandle klass) { if (klass->itable_length() == 0) return; assert(!klass->is_interface(), "Should have zero length itable"); // Count no of interfaces and total number of interface methods CountInterfacesClosure cic; visit_all_interfaces(klass->transitive_interfaces(), &cic); int nof_methods = cic.nof_methods(); int nof_interfaces = cic.nof_interfaces(); // Add one extra entry so we can null-terminate the table nof_interfaces++; assert(compute_itable_size(klass->transitive_interfaces()) == calc_itable_size(nof_interfaces, nof_methods), "mismatch calculation of itable size"); // Fill-out offset table itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); intptr_t* end = klass->end_of_itable(); assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); // Visit all interfaces and initialize itable offset table SetupItableClosure sic((address)klass(), ioe, ime); visit_all_interfaces(klass->transitive_interfaces(), &sic); #ifdef ASSERT ime = sic.method_entry(); oop* v = (oop*) klass->end_of_itable(); assert( (oop*)(ime) == v, "wrong offset calculation (2)"); #endif } // m must be a method in an interface int klassItable::compute_itable_index(Method* m) { Klass* intf = m->method_holder(); assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); Array* methods = InstanceKlass::cast(intf)->methods(); int index = 0; while(methods->at(index) != m) { index++; assert(index < methods->length(), "should find index for resolve_invoke"); } // Adjust for , which is left out of table if first method if (methods->length() > 0 && methods->at(0)->is_static_initializer()) { index--; } return index; } // inverse to compute_itable_index Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); Array* methods = InstanceKlass::cast(intf)->methods(); int index = itable_index; // Adjust for , which is left out of table if first method if (methods->length() > 0 && methods->at(0)->is_static_initializer()) { index++; } if (itable_index < 0 || index >= methods->length()) return NULL; // help caller defend against bad indexes Method* m = methods->at(index); assert(compute_itable_index(m) == itable_index, "correct inverse"); return m; } void klassVtable::verify(outputStream* st, bool forced) { // make sure table is initialized if (!Universe::is_fully_initialized()) return; #ifndef PRODUCT // avoid redundant verifies if (!forced && _verify_count == Universe::verify_count()) return; _verify_count = Universe::verify_count(); #endif oop* end_of_obj = (oop*)_klass() + _klass()->size(); oop* end_of_vtable = (oop *)&table()[_length]; if (end_of_vtable > end_of_obj) { fatal(err_msg("klass %s: klass object too short (vtable extends beyond " "end)", _klass->internal_name())); } for (int i = 0; i < _length; i++) table()[i].verify(this, st); // verify consistency with superKlass vtable Klass* super = _klass->super(); if (super != NULL) { InstanceKlass* sk = InstanceKlass::cast(super); klassVtable* vt = sk->vtable(); for (int i = 0; i < vt->length(); i++) { verify_against(st, vt, i); } } } void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { vtableEntry* vte = &vt->table()[index]; if (vte->method()->name() != table()[index].method()->name() || vte->method()->signature() != table()[index].method()->signature()) { fatal("mismatched name/signature of vtable entries"); } } #ifndef PRODUCT void klassVtable::print() { ResourceMark rm; tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); for (int i = 0; i < length(); i++) { table()[i].print(); tty->cr(); } } #endif void vtableEntry::verify(klassVtable* vt, outputStream* st) { NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); assert(method() != NULL, "must have set method"); method()->verify(); // we sub_type, because it could be a miranda method if (!vt->klass()->is_subtype_of(method()->method_holder())) { #ifndef PRODUCT print(); #endif fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this)); } } #ifndef PRODUCT void vtableEntry::print() { ResourceMark rm; tty->print("vtableEntry %s: ", method()->name()->as_C_string()); if (Verbose) { tty->print("m %#lx ", (address)method()); } } class VtableStats : AllStatic { public: static int no_klasses; // # classes with vtables static int no_array_klasses; // # array classes static int no_instance_klasses; // # instanceKlasses static int sum_of_vtable_len; // total # of vtable entries static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only static int fixed; // total fixed overhead in bytes static int filler; // overhead caused by filler bytes static int entries; // total bytes consumed by vtable entries static int array_entries; // total bytes consumed by array vtable entries static void do_class(Klass* k) { Klass* kl = k; klassVtable* vt = kl->vtable(); if (vt == NULL) return; no_klasses++; if (kl->oop_is_instance()) { no_instance_klasses++; kl->array_klasses_do(do_class); } if (kl->oop_is_array()) { no_array_klasses++; sum_of_array_vtable_len += vt->length(); } sum_of_vtable_len += vt->length(); } static void compute() { SystemDictionary::classes_do(do_class); fixed = no_klasses * oopSize; // vtable length // filler size is a conservative approximation filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); entries = sizeof(vtableEntry) * sum_of_vtable_len; array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; } }; int VtableStats::no_klasses = 0; int VtableStats::no_array_klasses = 0; int VtableStats::no_instance_klasses = 0; int VtableStats::sum_of_vtable_len = 0; int VtableStats::sum_of_array_vtable_len = 0; int VtableStats::fixed = 0; int VtableStats::filler = 0; int VtableStats::entries = 0; int VtableStats::array_entries = 0; void klassVtable::print_statistics() { ResourceMark rm; HandleMark hm; VtableStats::compute(); tty->print_cr("vtable statistics:"); tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); tty->print_cr("%6d bytes filler overhead", VtableStats::filler); tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); tty->print_cr("%6d bytes total", total); } bool klassVtable::check_no_old_entries() { // Check that there really is no entry for (int i = 0; i < length(); i++) { Method* m = unchecked_method_at(i); if (m != NULL) { if (!m->is_valid() || m->is_old()) { return false; } } } return true; } void klassVtable::dump_vtable() { tty->print_cr("vtable dump --"); for (int i = 0; i < length(); i++) { Method* m = unchecked_method_at(i); if (m != NULL) { tty->print(" (%5d) ", i); m->access_flags().print_on(tty); tty->print(" -- "); m->print_name(tty); tty->cr(); } } } bool klassItable::check_no_old_entries() { itableMethodEntry* ime = method_entry(0); for(int i = 0; i < _size_method_table; i++) { Method* m = ime->method(); if (m != NULL && (!m->is_valid() || m->is_old())) return false; ime++; } return true; } int klassItable::_total_classes; // Total no. of classes with itables long klassItable::_total_size; // Total no. of bytes used for itables void klassItable::print_statistics() { tty->print_cr("itable statistics:"); tty->print_cr("%6d classes with itables", _total_classes); tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes); } #endif // PRODUCT