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 /*

  * Copyright (c) 1997, 2013, 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, and none of C's superclasses implements I.

 // Let's say there is an abstract 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<Method*>* all_mirandas, Klass* super,

     Array<Method*>* methods, AccessFlags class_flags,

     Handle classloader, Symbol* classname, Array<Klass*>* 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<Method*> new_mirandas(20);

   // compute the number of mirandas methods that must be added to the end

   get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces);

   *num_new_mirandas = new_mirandas.length();

   // Interfaces do not need interface methods in their vtables

   // This includes miranda methods and during later processing, default methods

   if (!class_flags.is_interface()) {

     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->has_vtable_index(), "do not ask this of non-vtable methods");

   return m->vtable_index();

 }

 // Copy super class's vtable to the first part (prefix) of this class's vtable,

 // and return the number of entries copied.  Expects that 'super' is the Java

 // super class (arrays can have "array" super classes that must be skipped).

 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 (Kestrel 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<Method*>* methods = ik()->methods();

     int len = methods->length();

     int initialized = super_vtable_len;

     // Check each of this class's methods against super;

     // if override, replace in copy of super vtable, otherwise append to end

     for (int i = 0; i < len; i++) {

       // update_inherited_vtable can stop for gc - ensure using handles

       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, -1, checkconstraints, CHECK);

       if (needs_new_entry) {

         put_method_at(mh(), initialized);

         mh()->set_vtable_index(initialized); // set primary vtable index

         initialized++;

       }

     }

     // update vtable with default_methods

     Array<Method*>* default_methods = ik()->default_methods();

     if (default_methods != NULL) {

       len = default_methods->length();

       if (len > 0) {

         Array<int>* def_vtable_indices = NULL;

         if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {

           def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);

         } else {

           assert(def_vtable_indices->length() == len, "reinit vtable len?");

         }

         for (int i = 0; i < len; i++) {

           HandleMark hm(THREAD);

           assert(default_methods->at(i)->is_method(), "must be a Method*");

           methodHandle mh(THREAD, default_methods->at(i));

           bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);

           // needs new entry

           if (needs_new_entry) {

             put_method_at(mh(), initialized);

             def_vtable_indices->at_put(i, initialized); //set vtable index

             initialized++;

           }

         }

       }

     }

     // add miranda methods; it will also return the updated initialized

     // Interfaces do not need interface methods in their vtables

     // This includes miranda methods and during later processing, default methods

     if (!ik()->is_interface()) {

       initialized = fill_in_mirandas(initialized);

     }

     // In class hierarchies where the accessibility is not increasing (i.e., going from private ->

     // package_private -> public/protected), 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);

           char* sig = target_method()->name_and_sig_as_C_string();

           tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",

            supersuperklass->internal_name(),

            _klass->internal_name(), sig, vtable_index);

            super_method->access_flags().print_on(tty);

            if (super_method->is_default_method()) {

              tty->print("default ");

            }

            tty->print("overriders flags: ");

            target_method->access_flags().print_on(tty);

            if (target_method->is_default_method()) {

              tty->print("default ");

            }

         }

 #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, int default_index,

                                           bool checkconstraints, TRAPS) {

   ResourceMark rm;

   bool allocate_new = true;

   assert(klass->oop_is_instance(), "must be InstanceKlass");

   Array<int>* def_vtable_indices = NULL;

   bool is_default = false;

   // default methods are concrete methods in superinterfaces which are added to the vtable

   // with their real method_holder

   // Since vtable and itable indices share the same storage, don't touch

   // the default method's real vtable/itable index

   // default_vtable_indices stores the vtable value relative to this inheritor

   if (default_index >= 0 ) {

     is_default = true;

     def_vtable_indices = klass->default_vtable_indices();

     assert(def_vtable_indices != NULL, "def vtable alloc?");

     assert(default_index <= def_vtable_indices->length(), "def vtable len?");

   } else {

     assert(klass == target_method()->method_holder(), "caller resp.");

     // 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 <init> methods are never in

   if (target_method()->is_static() || target_method()->name() ==  vmSymbols::object_initializer_name()) {

     return false;

   }

   if (target_method->is_final_method(klass->access_flags())) {

     // 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;

   } else if (klass->is_interface()) {

     allocate_new = false;  // see note below in needs_new_vtable_entry

     // An interface never allocates new vtable slots, only inherits old ones.

     // This method will either be assigned its own itable index later,

     // or be assigned an inherited vtable index in the loop below.

     // default methods inherited by classes store their vtable indices

     // in the inheritor's default_vtable_indices

     // default methods inherited by interfaces may already have a

     // valid itable index, if so, don't change it

     // overpass methods in an interface will be assigned an itable index later

     // by an inheriting class

     if (!is_default || !target_method()->has_itable_index()) {

       target_method()->set_vtable_index(Method::pending_itable_index);

     }

   }

   // we need a new entry if there is no superclass

   if (klass->super() == NULL) {

     return allocate_new;

   }

   // private methods in classes always have a new entry in the vtable

   // specification interpretation since classic has

   // private methods not overriding

   // JDK8 adds private methods in interfaces which require invokespecial

   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();

   KlassHandle target_klass(THREAD, target_method()->method_holder());

   if (target_klass == NULL) {

     target_klass = _klass;

   }

   Handle target_loader(THREAD, target_klass->class_loader());

   Symbol* target_classname = target_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 =  super_method->method_holder();

       if (is_default

           || ((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);

             Symbol* failed_type_symbol =

               SystemDictionary::check_signature_loaders(signature, target_loader,

                                                         super_loader, true,

                                                         CHECK_(false));

             if (failed_type_symbol != 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 = target_klass->name()->as_C_string();

               const char* loader2 = SystemDictionary::loader_name(super_loader());

               char* failed_type_name = failed_type_symbol->as_C_string();

               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);

        if (!is_default) {

          target_method()->set_vtable_index(i);

        } else {

          if (def_vtable_indices != NULL) {

            def_vtable_indices->at_put(default_index, i);

          }

          assert(super_method->is_default_method() || super_method->is_overpass()

                 || super_method->is_abstract(), "default override error");

        }

 #ifndef PRODUCT

         if (PrintVtables && Verbose) {

           ResourceMark rm(THREAD);

           char* sig = target_method()->name_and_sig_as_C_string();

           tty->print("overriding with %s::%s index %d, original flags: ",

            target_klass->internal_name(), sig, i);

            super_method->access_flags().print_on(tty);

            if (super_method->is_default_method()) {

              tty->print("default ");

            }

            if (super_method->is_overpass()) {

              tty->print("overpass");

            }

            tty->print("overriders flags: ");

            target_method->access_flags().print_on(tty);

            if (target_method->is_default_method()) {

              tty->print("default ");

            }

            if (target_method->is_overpass()) {

              tty->print("overpass");

            }

            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) {

           ResourceMark rm(THREAD);

           char* sig = target_method()->name_and_sig_as_C_string();

           tty->print("NOT overriding with %s::%s index %d, original flags: ",

            target_klass->internal_name(), sig,i);

            super_method->access_flags().print_on(tty);

            if (super_method->is_default_method()) {

              tty->print("default ");

            }

            if (super_method->is_overpass()) {

              tty->print("overpass");

            }

            tty->print("overriders flags: ");

            target_method->access_flags().print_on(tty);

            if (target_method->is_default_method()) {

              tty->print("default ");

            }

            if (target_method->is_overpass()) {

              tty->print("overpass");

            }

            tty->cr();

         }

 #endif /*PRODUCT*/

       }

     }

   }

   return allocate_new;

 }

 void klassVtable::put_method_at(Method* m, int index) {

 #ifndef PRODUCT

   if (PrintVtables && Verbose) {

     ResourceMark rm;

     const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";

     tty->print("adding %s at index %d, flags: ", sig, index);

     if (m != NULL) {

       m->access_flags().print_on(tty);

       if (m->is_default_method()) {

         tty->print("default ");

       }

       if (m->is_overpass()) {

         tty->print("overpass");

       }

     }

     tty->cr();

   }

 #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 (class_flags.is_interface()) {

     // Interfaces do not use vtables, so there is no point to assigning

     // a vtable index to any of their methods.  If we refrain from doing this,

     // we can use Method::_vtable_index to hold the itable index

     return false;

   }

   if (target_method->is_final_method(class_flags) ||

       // 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;

   }

   // Concrete interface methods do not need new entries, they override

   // abstract method entries using default inheritance rules

   if (target_method()->method_holder() != NULL &&

       target_method()->method_holder()->is_interface()  &&

       !target_method()->is_abstract() ) {

     return false;

   }

   // we need a new entry if there is no superclass

   if (super == NULL) {

     return true;

   }

   // private methods in classes always have a new entry in the vtable

   // specification interpretation since classic has

   // private methods not overriding

   // JDK8 adds private  methods in interfaces which require invokespecial

   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 = 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 at an index is miranda

 // requires that method m at entry be declared ("held") by an interface.

 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 public abstract instance 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");

     // the search could find a miranda or a default method

     if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {

       return true;

     }

   }

   return false;

 }

 // check if a method is a miranda method, given a class's methods table,

 // its default_method table  and its super

 // "miranda" means not static, not defined by this class.

 // private methods in interfaces do not belong in the miranda list.

 // the caller must make sure that the method belongs to an interface implemented by the class

 // Miranda methods only include public interface instance methods

 // Not private methods, not static methods, not default == concrete abstract

 // Miranda methods also do not include overpass methods in interfaces

 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,

                              Array<Method*>* default_methods, Klass* super) {

   if (m->is_static() || m->is_private() || m->is_overpass()) {

     return false;

   }

   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 ((default_methods == NULL) ||

         InstanceKlass::find_method(default_methods, name, signature) == NULL) {

       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;

 }

 // Scans current_interface_methods for miranda methods that do not

 // already appear in new_mirandas, or default methods,  and are also not defined-and-non-private

 // in super (superclass).  These mirandas are added to all_mirandas if it is

 // not null; in addition, those that are not duplicates of miranda methods

 // inherited by super from its interfaces are added to new_mirandas.

 // Thus, new_mirandas will be the set of mirandas that this class introduces,

 // all_mirandas will be the set of all mirandas applicable to this class

 // including all defined in superclasses.

 void klassVtable::add_new_mirandas_to_lists(

     GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,

     Array<Method*>* current_interface_methods, Array<Method*>* class_methods,

     Array<Method*>* default_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, default_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<Method*>* new_mirandas,

                                GrowableArray<Method*>* all_mirandas,

                                Klass* super, Array<Method*>* class_methods,

                                Array<Method*>* default_methods,

                                Array<Klass*>* 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,

                               default_methods, super);

     // iterate thru each local's super interfaces

     Array<Klass*>* 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,

                                 default_methods, super);

     }

   }

 }

 // Discover miranda methods ("miranda" = "interface abstract, no binding"),

 // and append them into the vtable starting at index initialized,

 // return the new value of initialized.

 // Miranda methods use vtable entries, but do not get assigned a vtable_index

 // The vtable_index is discovered by searching from the end of the vtable

 int klassVtable::fill_in_mirandas(int initialized) {

   GrowableArray<Method*> mirandas(20);

   get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),

                ik()->default_methods(), ik()->local_interfaces());

   for (int i = 0; i < mirandas.length(); i++) {

     if (PrintVtables && Verbose) {

       Method* meth = mirandas.at(i);

       ResourceMark rm(Thread::current());

       if (meth != NULL) {

         char* sig = meth->name_and_sig_as_C_string();

         tty->print("fill in mirandas with %s index %d, flags: ",

           sig, initialized);

         meth->access_flags().print_on(tty);

         if (meth->is_default_method()) {

           tty->print("default ");

         }

         tty->cr();

       }

     }

     put_method_at(mirandas.at(i), initialized);

     ++initialized;

   }

   return initialized;

 }

 // Copy this class's vtable to the vtable beginning at start.

 // Used to copy superclass vtable to prefix of subclass's vtable.

 void klassVtable::copy_vtable_to(vtableEntry* start) {

   Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());

 }

 #if INCLUDE_JVMTI

 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {

   // If old_method is default, find this vtable index in default_vtable_indices

   // and replace that method in the _default_methods list

   bool updated = false;

   Array<Method*>* default_methods = ik()->default_methods();

   if (default_methods != NULL) {

     int len = default_methods->length();

     for (int idx = 0; idx < len; idx++) {

       if (vtable_index == ik()->default_vtable_indices()->at(idx)) {

         if (default_methods->at(idx) == old_method) {

           default_methods->at_put(idx, new_method);

           updated = true;

         }

         break;

       }

     }

   }

   return updated;

 }

 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);

           // For default methods, need to update the _default_methods array

           // which can only have one method entry for a given signature

           bool updated_default = false;

           if (old_method->is_default_method()) {

             updated_default = adjust_default_method(index, old_method, 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: klassname=%s for methods from name=%s",

                            klass()->external_name(),

                            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), updated default = %s",

                                 new_method->name()->as_C_string(),

                                 new_method->signature()->as_C_string(),

                                 updated_default ? "true" : "false"));

         }

         // cannot 'break' here; see for-loop comment above.

       }

     }

   }

 }

 // a vtable should never contain old or obsolete methods

 bool klassVtable::check_no_old_or_obsolete_entries() {

   for (int i = 0; i < length(); i++) {

     Method* m = unchecked_method_at(i);

     if (m != NULL &&

         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {

       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);

       if (m->is_default_method()) {

         tty->print("default ");

       }

       if (m->is_overpass()) {

         tty->print("overpass");

       }

       tty->print(" --  ");

       m->print_name(tty);

       tty->cr();

     }

   }

 }

 #endif // INCLUDE_JVMTI

 // 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) {

   if (_klass->is_interface()) {

     // This needs to go after vtable indices are assigned but

     // before implementors need to know the number of itable indices.

     assign_itable_indices_for_interface(_klass());

   }

   // 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");

 }

 inline bool interface_method_needs_itable_index(Method* m) {

   if (m->is_static())           return false;   // e.g., Stream.empty

   if (m->is_initializer())      return false;   // <init> or <clinit>

   // If an interface redeclares a method from java.lang.Object,

   // it should already have a vtable index, don't touch it.

   // e.g., CharSequence.toString (from initialize_vtable)

   // if (m->has_vtable_index())  return false; // NO!

   return true;

 }

 int klassItable::assign_itable_indices_for_interface(Klass* klass) {

   // an interface does not have an itable, but its methods need to be numbered

   if (TraceItables) tty->print_cr("%3d: Initializing itable for interface %s", ++initialize_count,

                                   klass->name()->as_C_string());

   Array<Method*>* methods = InstanceKlass::cast(klass)->methods();

   int nof_methods = methods->length();

   int ime_num = 0;

   for (int i = 0; i < nof_methods; i++) {

     Method* m = methods->at(i);

     if (interface_method_needs_itable_index(m)) {

       assert(!m->is_final_method(), "no final interface methods");

       // If m is already assigned a vtable index, do not disturb it.

       if (TraceItables && Verbose) {

         ResourceMark rm;

         const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";

         if (m->has_vtable_index()) {

           tty->print("itable index %d for method: %s, flags: ", m->vtable_index(), sig);

         } else {

           tty->print("itable index %d for method: %s, flags: ", ime_num, sig);

         }

         if (m != NULL) {

           m->access_flags().print_on(tty);

           if (m->is_default_method()) {

             tty->print("default ");

           }

           if (m->is_overpass()) {

             tty->print("overpass");

           }

         }

         tty->cr();

       }

       if (!m->has_vtable_index()) {

         assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable");

         m->set_itable_index(ime_num);

         // Progress to next itable entry

         ime_num++;

       }

     }

   }

   assert(ime_num == method_count_for_interface(klass), "proper sizing");

   return ime_num;

 }

 int klassItable::method_count_for_interface(Klass* interf) {

   assert(interf->oop_is_instance(), "must be");

   assert(interf->is_interface(), "must be");

   Array<Method*>* methods = InstanceKlass::cast(interf)->methods();

   int nof_methods = methods->length();

   while (nof_methods > 0) {

     Method* m = methods->at(nof_methods-1);

     if (m->has_itable_index()) {

       int length = m->itable_index() + 1;

 #ifdef ASSERT

       while (nof_methods = 0) {

         m = methods->at(--nof_methods);

         assert(!m->has_itable_index() || m->itable_index() < length, "");

       }

 #endif //ASSERT

       return length;  // return the rightmost itable index, plus one

     }

     nof_methods -= 1;

   }

   // no methods have itable indices

   return 0;

 }

 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {

   Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();

   int nof_methods = methods->length();

   HandleMark hm;

   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_count = method_count_for_interface(interf_h());

   for (int i = 0; i < nof_methods; i++) {

     Method* m = methods->at(i);

     methodHandle target;

     if (m->has_itable_index()) {

       LinkResolver::lookup_instance_method_in_klasses(target, _klass, m->name(), m->signature(), CHECK);

     }

     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

       if (checkconstraints) {

         Handle method_holder_loader (THREAD, target->method_holder()->class_loader());

         if (method_holder_loader() != interface_loader()) {

           ResourceMark rm(THREAD);

           Symbol* failed_type_symbol =

             SystemDictionary::check_signature_loaders(m->signature(),

                                                       method_holder_loader,

                                                       interface_loader,

                                                       true, CHECK);

           if (failed_type_symbol != 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()->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();

             char* failed_type_name = failed_type_symbol->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

       int ime_num = m->itable_index();

       assert(ime_num < ime_count, "oob");

       itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target());

       if (TraceItables && Verbose) {

         ResourceMark rm(THREAD);

         if (target() != NULL) {

           char* sig = target()->name_and_sig_as_C_string();

           tty->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",

                     interf_h()->internal_name(), ime_num, sig,

                     target()->method_holder()->internal_name());

           tty->print("target_method flags: ");

           target()->access_flags().print_on(tty);

           if (target()->is_default_method()) {

             tty->print("default ");

           }

           tty->cr();

         }

       }

     }

   }

 }

 // 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++;

   }

 }

 #if INCLUDE_JVMTI

 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",

               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' here; see for-loop comment above.

       }

       ime++;

     }

   }

 }

 // an itable should never contain old or obsolete methods

 bool klassItable::check_no_old_or_obsolete_entries() {

   itableMethodEntry* ime = method_entry(0);

   for (int i = 0; i < _size_method_table; i++) {

     Method* m = ime->method();

     if (m != NULL &&

         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {

       return false;

     }

     ime++;

   }

   return true;

 }

 void klassItable::dump_itable() {

   itableMethodEntry* ime = method_entry(0);

   tty->print_cr("itable dump --");

   for (int i = 0; i < _size_method_table; i++) {

     Method* m = ime->method();

     if (m != NULL) {

       tty->print("      (%5d)  ", i);

       m->access_flags().print_on(tty);

       if (m->is_default_method()) {

         tty->print("default ");

       }

       tty->print(" --  ");

       m->print_name(tty);

       tty->cr();

     }

     ime++;

   }

 }

 #endif // INCLUDE_JVMTI

 // Setup

 class InterfaceVisiterClosure : public StackObj {

  public:

   virtual void doit(Klass* intf, int method_count) = 0;

 };

 // Visit all interfaces with at least one itable method

 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {

   // Handle array argument

   for(int i = 0; i < transitive_intf->length(); i++) {

     Klass* intf = transitive_intf->at(i);

     assert(intf->is_interface(), "sanity check");

     // Find no. of itable methods

     int method_count = 0;

     // method_count = klassItable::method_count_for_interface(intf);

     Array<Method*>* methods = InstanceKlass::cast(intf)->methods();

     if (methods->length() > 0) {

       for (int i = methods->length(); --i >= 0; ) {

         if (interface_method_needs_itable_index(methods->at(i))) {

           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<Klass*>* 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

 }

 // inverse to itable_index

 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {

   assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");

   assert(intf->verify_itable_index(itable_index), "");

   Array<Method*>* methods = InstanceKlass::cast(intf)->methods();

   if (itable_index < 0 || itable_index >= method_count_for_interface(intf))

     return NULL;                // help caller defend against bad indices

   int index = itable_index;

   Method* m = methods->at(index);

   int index2 = -1;

   while (!m->has_itable_index() ||

          (index2 = m->itable_index()) != itable_index) {

     assert(index2 < itable_index, "monotonic");

     if (++index == methods->length())

       return NULL;

     m = methods->at(index);

   }

   assert(m->itable_index() == 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);

 }

 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