jdk8-mips64-public/hotspot: src/share/vm/oops/klassVtable.cpp@624a0741915c (annotated)

src/share/vm/oops/klassVtable.cpp@624a0741915c (annotated)

src/share/vm/oops/klassVtable.cpp

Thu, 04 Apr 2019 17:56:29 +0800

author: aoqi
date: Thu, 04 Apr 2019 17:56:29 +0800
changeset 9572: 624a0741915c
parent 9041: 95a08233f46c
child 9756: 2be326848943
permissions: -rw-r--r--

Merge

 /*
  * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "gc_implementation/shared/markSweep.inline.hpp"
 #include "memory/gcLocker.hpp"
 #include "memory/metaspaceShared.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"
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 inline InstanceKlass* klassVtable::ik() const {
   Klass* k = _klass();
   assert(k->oop_is_instance(), "not an InstanceKlass");
   return (InstanceKlass*)k;
 }
 bool klassVtable::is_preinitialized_vtable() {
   return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
 }
 // 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 if (is_preinitialized_vtable()) {
     // A shared class' vtable is preinitialized at dump time. No need to copy
     // methods from super class for shared class, as that was already done
     // during archiving time. However, if Jvmti has redefined a class,
     // copy super class's vtable in case the super class has changed.
     return super->vtable()->length();
   } 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;
   bool is_shared = _klass->is_shared();
   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()) {
     assert(!is_shared, "sanity");
     // 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) {
           assert(!is_shared, "shared class def_vtable_indices does not exist");
           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);
             if (is_preinitialized_vtable()) {
               // At runtime initialize_vtable is rerun for a shared class
               // (loaded by the non-boot loader) as part of link_class_impl().
               // The dumptime vtable index should be the same as the runtime index.
               assert(def_vtable_indices->at(i) == initialized,
                      "dump time vtable index is different from runtime index");
             } else {
               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
 // For public and protected methods: if they override a superclass, they will
 // also be overridden themselves appropriately.
 // Private methods do not override and are not overridden.
 // Package Private methods are trickier:
 // e.g. P1.A, pub m
 // P2.B extends A, package private m
 // P1.C extends B, public m
 // P1.C.m needs to override P1.A.m and can not override P2.B.m
 // Therefore: all package private methods need their own vtable entries for
 // them to be the root of an inheritance overriding decision
 // Package private methods may also override other vtable entries
 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
   Klass* super = klass->super();
   if (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;
     if (is_preinitialized_vtable()) {
       // If this is a shared class, the vtable is already in the final state (fully
       // initialized). Need to look at the super's vtable.
       klassVtable* superVtable = super->vtable();
       super_method = superVtable->method_at(i);
     } else {
       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();
       // private methods are also never overridden
       if (!super_method->is_private() &&
           (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)))))
         {
         // Package private methods always need a new entry to root their own
         // overriding. They may also override other methods.
         if (!target_method()->is_package_private()) {
           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) {
            if (is_preinitialized_vtable()) {
              // At runtime initialize_vtable is rerun as part of link_class_impl()
              // for a shared class loaded by the non-boot loader.
              // The dumptime vtable index should be the same as the runtime index.
              assert(def_vtable_indices->at(default_index) == i,
                     "dump time vtable index is different from runtime index");
            } else {
              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) {
   if (is_preinitialized_vtable()) {
     // At runtime initialize_vtable is rerun as part of link_class_impl()
     // for shared class loaded by the non-boot loader to obtain the loader
     // constraints based on the runtime classloaders' context. The dumptime
     // method at the vtable index should be the same as the runtime method.
     assert(table()[index].method() == m,
            "archived method is different from the runtime method");
   } else {
 #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, except for java.lang.Object methods,
     // so there is no point to assigning
     // a vtable index to any of their local 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;
   }
   // Package private methods always need a new entry to root their own
   // overriding. This allows transitive overriding to work.
   if (target_method()->is_package_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, Klass::find_defaults) != 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");
     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 array,
 // its default_method table and its super class.
 // "Miranda" means an abstract non-private method that would not be
 // overridden for the local class.
 // A "miranda" method should only include non-private interface
 // instance methods, i.e. not private methods, not static methods,
 // not default methods (concrete interface methods), not overpass methods.
 // If a given class already has a local (including overpass) method, a
 // default method, or any of its superclasses has the same which would have
 // overridden an abstract method, then this is not a miranda method.
 //
 // Miranda methods are checked multiple times.
 // Pass 1: during class load/class file parsing: before vtable size calculation:
 // include superinterface abstract and default methods (non-private instance).
 // We include potential default methods to give them space in the vtable.
 // During the first run, the current instanceKlass has not yet been
 // created, the superclasses and superinterfaces do have instanceKlasses
 // but may not have vtables, the default_methods list is empty, no overpasses.
 // This is seen by default method creation.
 //
 // Pass 2: recalculated during vtable initialization: only include abstract methods.
 // The goal of pass 2 is to walk through the superinterfaces to see if any of
 // the superinterface methods (which were all abstract pre-default methods)
 // need to be added to the vtable.
 // With the addition of default methods, we have three new challenges:
 // overpasses, static interface methods and private interface methods.
 // Static and private interface methods do not get added to the vtable and
 // are not seen by the method resolution process, so we skip those.
 // Overpass methods are already in the vtable, so vtable lookup will
 // find them and we don't need to add a miranda method to the end of
 // the vtable. So we look for overpass methods and if they are found we
 // return false. Note that we inherit our superclasses vtable, so
 // the superclass' search also needs to use find_overpass so that if
 // one is found we return false.
 // False means - we don't need a miranda method added to the vtable.
 //
 // During the second run, default_methods is set up, so concrete methods from
 // superinterfaces with matching names/signatures to default_methods are already
 // in the default_methods list and do not need to be appended to the vtable
 // as mirandas. Abstract methods may already have been handled via
 // overpasses - either local or superclass overpasses, which may be
 // in the vtable already.
 //
 // Pass 3: They are also checked by link resolution and selection,
 // for invocation on a method (not interface method) reference that
 // resolves to a method with an interface as its method_holder.
 // Used as part of walking from the bottom of the vtable to find
 // the vtable index for the miranda method.
 //
 // Part of the Miranda Rights in the US mean that if you do not have
 // an attorney one will be appointed for you.
 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();
   // First look in local methods to see if already covered
   if (InstanceKlass::find_local_method(class_methods, name, signature,
               Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
   {
     return false;
   }
   // Check local default methods
   if ((default_methods != NULL) &&
     (InstanceKlass::find_method(default_methods, name, signature) != NULL))
    {
      return false;
    }
   InstanceKlass* cursuper;
   // Iterate on all superclasses, which should have instanceKlasses
   // Note that we explicitly look for overpasses at each level.
   // Overpasses may or may not exist for supers for pass 1,
   // they should have been created for pass 2 and later.
   for (cursuper = InstanceKlass::cast(super); cursuper != NULL;  cursuper = (InstanceKlass*)cursuper->super())
   {
      if (cursuper->find_local_method(name, signature,
            Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) {
        return false;
      }
   }
   return true;
 }
 // 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(), Klass::find_defaults) == 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;
 }
 // search the vtable for uses of either obsolete or EMCP methods
 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
   int prn_enabled = 0;
   for (int index = 0; index < length(); index++) {
     Method* old_method = unchecked_method_at(index);
     if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
       continue; // skip uninteresting entries
     }
     assert(!old_method->is_deleted(), "vtable methods may not be deleted");
     Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
     assert(new_method != NULL, "method_with_idnum() should not be NULL");
     assert(old_method != new_method, "sanity check");
     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"));
     }
   }
 }
 // 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;
   if (MetaspaceShared::is_in_shared_space((void*)&_method) &&
      !MetaspaceShared::remapped_readwrite()) {
     // At runtime initialize_itable is rerun as part of link_class_impl()
     // for a shared class loaded by the non-boot loader.
     // The dumptime itable method entry should be the same as the runtime entry.
     assert(_method == m, "sanity");
   } else {
     _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()) {
         // A shared method could have an initialized itable_index that
         // is < 0.
         assert(m->vtable_index() == Method::pending_itable_index ||
                m->is_shared(),
                "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;
   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()) {
       // This search must match the runtime resolution, i.e. selection search for invokeinterface
       // to correctly enforce loader constraints for interface method inheritance
       LinkResolver::lookup_instance_method_in_klasses(target, _klass, m->name(), m->signature(), CHECK);
     }
     if (target == NULL || !target->is_public() || target->is_abstract()) {
       // Entry does not resolve. Leave it empty for AbstractMethodError.
         if (!(target == NULL) && !target->is_public()) {
           // Stuff an IllegalAccessError throwing method in there instead.
           itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()].
               initialize(Universe::throw_illegal_access_error());
         }
     } 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
 // search the itable for uses of either obsolete or EMCP methods
 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
   itableMethodEntry* ime = method_entry(0);
   for (int i = 0; i < _size_method_table; i++, ime++) {
     Method* old_method = ime->method();
     if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
       continue; // skip uninteresting entries
     }
     assert(!old_method->is_deleted(), "itable methods may not be deleted");
     Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
     assert(new_method != NULL, "method_with_idnum() should not be NULL");
     assert(old_method != new_method, "sanity check");
     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()));
     }
   }
 }
 // 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++;
         }
       }
     }
     // Visit all interfaces which either have any methods or can participate in receiver type check.
     // We do not bother to count methods in transitive interfaces, although that would allow us to skip
     // this step in the rare case of a zero-method interface extending another zero-method interface.
     if (method_count > 0 || InstanceKlass::cast(intf)->transitive_interfaces()->length() > 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

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/oops/klassVtable.cpp@624a0741915c (annotated)

src/share/vm/oops/klassVtable.cpp