Mercurial > hg > graal-jvmci-8
view src/share/vm/oops/klassVtable.cpp @ 3979:4dfb2df418f2
6484982: G1: process references during evacuation pauses
Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp
author | johnc |
---|---|
date | Thu, 22 Sep 2011 10:57:37 -0700 |
parents | 8ce625481709 |
children | da91efe96a93 |
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/* * Copyright (c) 1997, 2011, 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/klassOop.hpp" #include "oops/klassVtable.hpp" #include "oops/methodOop.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()->klass_part(); 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, int &num_miranda_methods, klassOop super, objArrayOop methods, AccessFlags class_flags, Handle classloader, Symbol* classname, objArrayOop local_interfaces, TRAPS ) { No_Safepoint_Verifier nsv; // set up default result values vtable_length = 0; num_miranda_methods = 0; // start off with super's vtable length instanceKlass* sk = (instanceKlass*)super->klass_part(); 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->obj_at(i)->is_method(), "must be a methodOop"); methodHandle mh(THREAD, methodOop(methods->obj_at(i))); if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) { vtable_length += vtableEntry::size(); // we need a new entry } } // compute the number of mirandas methods that must be added to the end num_miranda_methods = get_num_mirandas(super, methods, local_interfaces); vtable_length += (num_miranda_methods * 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"); } int klassVtable::index_of(methodOop 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()->klass_part(); 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"); objArrayHandle methods(THREAD, 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()->obj_at(i)->is_method(), "must be a methodOop"); methodHandle mh(THREAD, (methodOop)methods()->obj_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()) { methodOop 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() : "<NULL>", 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; } // 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(methodOopDesc::nonvirtual_vtable_index); // Static and <init> methods are never in if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { return false; } if (klass->is_final() || target_method()->is_final()) { // 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++) { methodOop 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() : "<NULL>", 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() : "<NULL>", 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(methodOop m, int index) { assert(m->is_oop_or_null(), "Not an oop or null"); #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() : "<NULL>", index); } assert(unchecked_method_at(index)->is_oop_or_null(), "Not an oop or null"); #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, klassOop super, Handle classloader, Symbol* classname, AccessFlags class_flags, TRAPS) { if ((class_flags.is_final() || target_method()->is_final()) || // 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()) // <init> 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(); klassOop k = super; methodOop super_method = NULL; instanceKlass *holder = NULL; methodOop 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--) { methodOop m = table()[i].method(); if (is_miranda_entry_at(i) && m->name() == name && m->signature() == signature) { return i; } } return methodOopDesc::invalid_vtable_index; } // check if an entry is miranda bool klassVtable::is_miranda_entry_at(int i) { methodOop m = method_at(i); klassOop 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() && m->is_abstract(), "should be public and abstract"); 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(methodOop m, objArrayOop class_methods, klassOop 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; } methodOop 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_list(GrowableArray<methodOop>* list_of_current_mirandas, objArrayOop current_interface_methods, objArrayOop class_methods, klassOop 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++) { methodOop im = methodOop(current_interface_methods->obj_at(i)); bool is_duplicate = false; int num_of_current_mirandas = list_of_current_mirandas->length(); // check for duplicate mirandas in different interfaces we implement for (int j = 0; j < num_of_current_mirandas; j++) { methodOop miranda = list_of_current_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) { list_of_current_mirandas->append(im); } } } } } void klassVtable::get_mirandas(GrowableArray<methodOop>* mirandas, klassOop super, objArrayOop class_methods, objArrayOop local_interfaces) { assert((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(klassOop(local_interfaces->obj_at(i))); add_new_mirandas_to_list(mirandas, ik->methods(), class_methods, super); // iterate thru each local's super interfaces objArrayOop 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(klassOop(super_ifs->obj_at(j))); add_new_mirandas_to_list(mirandas, sik->methods(), class_methods, super); } } } // get number of mirandas int klassVtable::get_num_mirandas(klassOop super, objArrayOop class_methods, objArrayOop local_interfaces) { ResourceMark rm; GrowableArray<methodOop>* mirandas = new GrowableArray<methodOop>(20); get_mirandas(mirandas, super, class_methods, local_interfaces); return mirandas->length(); } // fill in mirandas void klassVtable::fill_in_mirandas(int& initialized) { ResourceMark rm; GrowableArray<methodOop>* mirandas = new GrowableArray<methodOop>(20); instanceKlass *this_ik = ik(); get_mirandas(mirandas, this_ik->super(), this_ik->methods(), this_ik->local_interfaces()); int num_mirandas = mirandas->length(); for (int i = 0; i < num_mirandas; 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(methodOop* old_methods, methodOop* 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++) { methodOop old_method = old_methods[j]; methodOop 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; } // Garbage collection void klassVtable::oop_follow_contents() { int len = length(); for (int i = 0; i < len; i++) { MarkSweep::mark_and_push(adr_method_at(i)); } } #ifndef SERIALGC void klassVtable::oop_follow_contents(ParCompactionManager* cm) { int len = length(); for (int i = 0; i < len; i++) { PSParallelCompact::mark_and_push(cm, adr_method_at(i)); } } #endif // SERIALGC void klassVtable::oop_adjust_pointers() { int len = length(); for (int i = 0; i < len; i++) { MarkSweep::adjust_pointer(adr_method_at(i)); } } #ifndef SERIALGC void klassVtable::oop_update_pointers(ParCompactionManager* cm) { const int n = length(); for (int i = 0; i < n; i++) { PSParallelCompact::adjust_pointer(adr_method_at(i)); } } #endif // SERIALGC // Iterators void klassVtable::oop_oop_iterate(OopClosure* blk) { int len = length(); for (int i = 0; i < len; i++) { blk->do_oop(adr_method_at(i)); } } void klassVtable::oop_oop_iterate_m(OopClosure* blk, MemRegion mr) { int len = length(); int i; for (i = 0; i < len; i++) { if ((HeapWord*)adr_method_at(i) >= mr.start()) break; } for (; i < len; i++) { oop* adr = adr_method_at(i); if ((HeapWord*)adr < mr.end()) blk->do_oop(adr); } } //----------------------------------------------------------------------------------------- // Itable code // Initialize a itableMethodEntry void itableMethodEntry::initialize(methodOop 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->as_klassOop()) + offset_entry->offset()); intptr_t* end = klass->end_of_itable(); _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass->as_klassOop(); _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; } // Garbage Collection void klassItable::oop_follow_contents() { // offset table itableOffsetEntry* ioe = offset_entry(0); for(int i = 0; i < _size_offset_table; i++) { MarkSweep::mark_and_push((oop*)&ioe->_interface); ioe++; } // method table itableMethodEntry* ime = method_entry(0); for(int j = 0; j < _size_method_table; j++) { MarkSweep::mark_and_push((oop*)&ime->_method); ime++; } } #ifndef SERIALGC void klassItable::oop_follow_contents(ParCompactionManager* cm) { // offset table itableOffsetEntry* ioe = offset_entry(0); for(int i = 0; i < _size_offset_table; i++) { PSParallelCompact::mark_and_push(cm, (oop*)&ioe->_interface); ioe++; } // method table itableMethodEntry* ime = method_entry(0); for(int j = 0; j < _size_method_table; j++) { PSParallelCompact::mark_and_push(cm, (oop*)&ime->_method); ime++; } } #endif // SERIALGC void klassItable::oop_adjust_pointers() { // offset table itableOffsetEntry* ioe = offset_entry(0); for(int i = 0; i < _size_offset_table; i++) { MarkSweep::adjust_pointer((oop*)&ioe->_interface); ioe++; } // method table itableMethodEntry* ime = method_entry(0); for(int j = 0; j < _size_method_table; j++) { MarkSweep::adjust_pointer((oop*)&ime->_method); ime++; } } #ifndef SERIALGC void klassItable::oop_update_pointers(ParCompactionManager* cm) { // offset table itableOffsetEntry* ioe = offset_entry(0); for(int i = 0; i < _size_offset_table; i++) { PSParallelCompact::adjust_pointer((oop*)&ioe->_interface); ioe++; } // method table itableMethodEntry* ime = method_entry(0); for(int j = 0; j < _size_method_table; j++) { PSParallelCompact::adjust_pointer((oop*)&ime->_method); ime++; } } #endif // SERIALGC // Iterators void klassItable::oop_oop_iterate(OopClosure* blk) { // offset table itableOffsetEntry* ioe = offset_entry(0); for(int i = 0; i < _size_offset_table; i++) { blk->do_oop((oop*)&ioe->_interface); ioe++; } // method table itableMethodEntry* ime = method_entry(0); for(int j = 0; j < _size_method_table; j++) { blk->do_oop((oop*)&ime->_method); ime++; } } void klassItable::oop_oop_iterate_m(OopClosure* blk, MemRegion mr) { // offset table itableOffsetEntry* ioe = offset_entry(0); for(int i = 0; i < _size_offset_table; i++) { oop* adr = (oop*)&ioe->_interface; if (mr.contains(adr)) blk->do_oop(adr); ioe++; } // method table itableMethodEntry* ime = method_entry(0); for(int j = 0; j < _size_method_table; j++) { oop* adr = (oop*)&ime->_method; if (mr.contains(adr)) blk->do_oop(adr); ime++; } } 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); 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) { objArrayHandle methods(THREAD, 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 methodOop if it is a class initializer int i = ((methodOop)methods()->obj_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++) { methodOop m = (methodOop)methods()->obj_at(i); Symbol* method_name = m->name(); Symbol* method_signature = m->signature(); // This is same code as in Linkresolver::lookup_instance_method_in_klasses methodOop target = klass->uncached_lookup_method(method_name, method_signature); while (target != NULL && target->is_static()) { // continue with recursive lookup through the superclass klassOop super = Klass::cast(target->method_holder())->super(); target = (super == NULL) ? methodOop(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 methodOop void klassItable::initialize_with_method(methodOop 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(methodOop* old_methods, methodOop* 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++) { methodOop old_method = old_methods[j]; methodOop 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())); } break; } ime++; } } } // Setup class InterfaceVisiterClosure : public StackObj { public: virtual void doit(klassOop intf, int method_count) = 0; }; // Visit all interfaces with at-least one method (excluding <clinit>) void visit_all_interfaces(objArrayOop transitive_intf, InterfaceVisiterClosure *blk) { // Handle array argument for(int i = 0; i < transitive_intf->length(); i++) { klassOop intf = (klassOop)transitive_intf->obj_at(i); assert(Klass::cast(intf)->is_interface(), "sanity check"); // Find no. of methods excluding a <clinit> int method_count = instanceKlass::cast(intf)->methods()->length(); if (method_count > 0) { methodOop m = (methodOop)instanceKlass::cast(intf)->methods()->obj_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(klassOop 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(klassOop 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(objArrayHandle 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(objArrayHandle(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->as_klassOop(), 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(methodOop m) { klassOop intf = m->method_holder(); assert(instanceKlass::cast(intf)->is_interface(), "sanity check"); objArrayOop methods = instanceKlass::cast(intf)->methods(); int index = 0; while(methods->obj_at(index) != m) { index++; assert(index < methods->length(), "should find index for resolve_invoke"); } // Adjust for <clinit>, which is left out of table if first method if (methods->length() > 0 && ((methodOop)methods->obj_at(0))->is_static_initializer()) { index--; } return index; } // inverse to compute_itable_index methodOop klassItable::method_for_itable_index(klassOop intf, int itable_index) { assert(instanceKlass::cast(intf)->is_interface(), "sanity check"); objArrayOop methods = instanceKlass::cast(intf)->methods(); int index = itable_index; // Adjust for <clinit>, which is left out of table if first method if (methods->length() > 0 && ((methodOop)methods->obj_at(0))->is_static_initializer()) { index++; } if (itable_index < 0 || index >= methods->length()) return NULL; // help caller defend against bad indexes methodOop m = (methodOop)methods->obj_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 klassOop 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(klassOop k) { Klass* kl = k->klass_part(); 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++) { methodOop m = unchecked_method_at(i); if (m != NULL) { if (m->is_old()) { return false; } } } return true; } void klassVtable::dump_vtable() { tty->print_cr("vtable dump --"); for (int i = 0; i < length(); i++) { methodOop 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(); } } } 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