1 /*
   2  * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/systemDictionary.hpp"
  27 #include "classfile/vmSymbols.hpp"
  28 #include "gc_implementation/shared/markSweep.inline.hpp"
  29 #include "memory/gcLocker.hpp"
  30 #include "memory/resourceArea.hpp"
  31 #include "memory/universe.inline.hpp"
  32 #include "oops/instanceKlass.hpp"
  33 #include "oops/klassVtable.hpp"
  34 #include "oops/method.hpp"
  35 #include "oops/objArrayOop.hpp"
  36 #include "oops/oop.inline.hpp"
  37 #include "prims/jvmtiRedefineClassesTrace.hpp"
  38 #include "runtime/arguments.hpp"
  39 #include "runtime/handles.inline.hpp"
  40 #include "utilities/copy.hpp"
  41 
  42 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  43 
  44 inline InstanceKlass* klassVtable::ik() const {
  45   Klass* k = _klass();
  46   assert(k->oop_is_instance(), "not an InstanceKlass");
  47   return (InstanceKlass*)k;
  48 }
  49 
  50 
  51 // this function computes the vtable size (including the size needed for miranda
  52 // methods) and the number of miranda methods in this class.
  53 // Note on Miranda methods: Let's say there is a class C that implements
  54 // interface I, and none of C's superclasses implements I.
  55 // Let's say there is an abstract method m in I that neither C
  56 // nor any of its super classes implement (i.e there is no method of any access,
  57 // with the same name and signature as m), then m is a Miranda method which is
  58 // entered as a public abstract method in C's vtable.  From then on it should
  59 // treated as any other public method in C for method over-ride purposes.
  60 void klassVtable::compute_vtable_size_and_num_mirandas(
  61     int* vtable_length_ret, int* num_new_mirandas,
  62     GrowableArray<Method*>* all_mirandas, Klass* super,
  63     Array<Method*>* methods, AccessFlags class_flags,
  64     Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
  65     TRAPS) {
  66   No_Safepoint_Verifier nsv;
  67 
  68   // set up default result values
  69   int vtable_length = 0;
  70 
  71   // start off with super's vtable length
  72   InstanceKlass* sk = (InstanceKlass*)super;
  73   vtable_length = super == NULL ? 0 : sk->vtable_length();
  74 
  75   // go thru each method in the methods table to see if it needs a new entry
  76   int len = methods->length();
  77   for (int i = 0; i < len; i++) {
  78     assert(methods->at(i)->is_method(), "must be a Method*");
  79     methodHandle mh(THREAD, methods->at(i));
  80 
  81     if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) {
  82       vtable_length += vtableEntry::size(); // we need a new entry
  83     }
  84   }
  85 
  86   GrowableArray<Method*> new_mirandas(20);
  87   // compute the number of mirandas methods that must be added to the end
  88   get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces);
  89   *num_new_mirandas = new_mirandas.length();
  90 
  91   // Interfaces do not need interface methods in their vtables
  92   // This includes miranda methods and during later processing, default methods
  93   if (!class_flags.is_interface()) {
  94     vtable_length += *num_new_mirandas * vtableEntry::size();
  95   }
  96 
  97   if (Universe::is_bootstrapping() && vtable_length == 0) {
  98     // array classes don't have their superclass set correctly during
  99     // bootstrapping
 100     vtable_length = Universe::base_vtable_size();
 101   }
 102 
 103   if (super == NULL && vtable_length != Universe::base_vtable_size()) {
 104     if (Universe::is_bootstrapping()) {
 105       // Someone is attempting to override java.lang.Object incorrectly on the
 106       // bootclasspath.  The JVM cannot recover from this error including throwing
 107       // an exception
 108       vm_exit_during_initialization("Incompatible definition of java.lang.Object");
 109     } else {
 110       // Someone is attempting to redefine java.lang.Object incorrectly.  The
 111       // only way this should happen is from
 112       // SystemDictionary::resolve_from_stream(), which will detect this later
 113       // and throw a security exception.  So don't assert here to let
 114       // the exception occur.
 115       vtable_length = Universe::base_vtable_size();
 116     }
 117   }
 118   assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
 119   assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
 120 
 121   *vtable_length_ret = vtable_length;
 122 }
 123 
 124 int klassVtable::index_of(Method* m, int len) const {
 125   assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
 126   return m->vtable_index();
 127 }
 128 
 129 // Copy super class's vtable to the first part (prefix) of this class's vtable,
 130 // and return the number of entries copied.  Expects that 'super' is the Java
 131 // super class (arrays can have "array" super classes that must be skipped).
 132 int klassVtable::initialize_from_super(KlassHandle super) {
 133   if (super.is_null()) {
 134     return 0;
 135   } else {
 136     // copy methods from superKlass
 137     // can't inherit from array class, so must be InstanceKlass
 138     assert(super->oop_is_instance(), "must be instance klass");
 139     InstanceKlass* sk = (InstanceKlass*)super();
 140     klassVtable* superVtable = sk->vtable();
 141     assert(superVtable->length() <= _length, "vtable too short");
 142 #ifdef ASSERT
 143     superVtable->verify(tty, true);
 144 #endif
 145     superVtable->copy_vtable_to(table());
 146 #ifndef PRODUCT
 147     if (PrintVtables && Verbose) {
 148       ResourceMark rm;
 149       tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length);
 150     }
 151 #endif
 152     return superVtable->length();
 153   }
 154 }
 155 
 156 //
 157 // Revised lookup semantics   introduced 1.3 (Kestrel beta)
 158 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
 159 
 160   // Note:  Arrays can have intermediate array supers.  Use java_super to skip them.
 161   KlassHandle super (THREAD, klass()->java_super());
 162   int nofNewEntries = 0;
 163 
 164   if (PrintVtables && !klass()->oop_is_array()) {
 165     ResourceMark rm(THREAD);
 166     tty->print_cr("Initializing: %s", _klass->name()->as_C_string());
 167   }
 168 
 169 #ifdef ASSERT
 170   oop* end_of_obj = (oop*)_klass() + _klass()->size();
 171   oop* end_of_vtable = (oop*)&table()[_length];
 172   assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
 173 #endif
 174 
 175   if (Universe::is_bootstrapping()) {
 176     // just clear everything
 177     for (int i = 0; i < _length; i++) table()[i].clear();
 178     return;
 179   }
 180 
 181   int super_vtable_len = initialize_from_super(super);
 182   if (klass()->oop_is_array()) {
 183     assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
 184   } else {
 185     assert(_klass->oop_is_instance(), "must be InstanceKlass");
 186 
 187     Array<Method*>* methods = ik()->methods();
 188     int len = methods->length();
 189     int initialized = super_vtable_len;
 190 
 191     // Check each of this class's methods against super;
 192     // if override, replace in copy of super vtable, otherwise append to end
 193     for (int i = 0; i < len; i++) {
 194       // update_inherited_vtable can stop for gc - ensure using handles
 195       HandleMark hm(THREAD);
 196       assert(methods->at(i)->is_method(), "must be a Method*");
 197       methodHandle mh(THREAD, methods->at(i));
 198 
 199       bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
 200 
 201       if (needs_new_entry) {
 202         put_method_at(mh(), initialized);
 203         mh()->set_vtable_index(initialized); // set primary vtable index
 204         initialized++;
 205       }
 206     }
 207 
 208     // update vtable with default_methods
 209     Array<Method*>* default_methods = ik()->default_methods();
 210     if (default_methods != NULL) {
 211       len = default_methods->length();
 212       if (len > 0) {
 213         Array<int>* def_vtable_indices = NULL;
 214         if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
 215           def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
 216         } else {
 217           assert(def_vtable_indices->length() == len, "reinit vtable len?");
 218         }
 219         for (int i = 0; i < len; i++) {
 220           HandleMark hm(THREAD);
 221           assert(default_methods->at(i)->is_method(), "must be a Method*");
 222           methodHandle mh(THREAD, default_methods->at(i));
 223 
 224           bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
 225 
 226           // needs new entry
 227           if (needs_new_entry) {
 228             put_method_at(mh(), initialized);
 229             def_vtable_indices->at_put(i, initialized); //set vtable index
 230             initialized++;
 231           }
 232         }
 233       }
 234     }
 235 
 236     // add miranda methods; it will also return the updated initialized
 237     // Interfaces do not need interface methods in their vtables
 238     // This includes miranda methods and during later processing, default methods
 239     if (!ik()->is_interface()) {
 240       initialized = fill_in_mirandas(initialized);
 241     }
 242 
 243     // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
 244     // package_private -> public/protected), the vtable might actually be smaller than our initial
 245     // calculation.
 246     assert(initialized <= _length, "vtable initialization failed");
 247     for(;initialized < _length; initialized++) {
 248       put_method_at(NULL, initialized);
 249     }
 250     NOT_PRODUCT(verify(tty, true));
 251   }
 252 }
 253 
 254 // Called for cases where a method does not override its superclass' vtable entry
 255 // For bytecodes not produced by javac together it is possible that a method does not override
 256 // the superclass's method, but might indirectly override a super-super class's vtable entry
 257 // If none found, return a null superk, else return the superk of the method this does override
 258 // For public and protected methods: if they override a superclass, they will
 259 // also be overridden themselves appropriately.
 260 // Private methods do not override and are not overridden.
 261 // Package Private methods are trickier:
 262 // e.g. P1.A, pub m
 263 // P2.B extends A, package private m
 264 // P1.C extends B, public m
 265 // P1.C.m needs to override P1.A.m and can not override P2.B.m
 266 // Therefore: all package private methods need their own vtable entries for
 267 // them to be the root of an inheritance overriding decision
 268 // Package private methods may also override other vtable entries
 269 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
 270                             int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
 271   InstanceKlass* superk = initialsuper;
 272   while (superk != NULL && superk->super() != NULL) {
 273     InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
 274     klassVtable* ssVtable = supersuperklass->vtable();
 275     if (vtable_index < ssVtable->length()) {
 276       Method* super_method = ssVtable->method_at(vtable_index);
 277 #ifndef PRODUCT
 278       Symbol* name= target_method()->name();
 279       Symbol* signature = target_method()->signature();
 280       assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
 281 #endif
 282       if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
 283 #ifndef PRODUCT
 284         if (PrintVtables && Verbose) {
 285           ResourceMark rm(THREAD);
 286           char* sig = target_method()->name_and_sig_as_C_string();
 287           tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
 288            supersuperklass->internal_name(),
 289            _klass->internal_name(), sig, vtable_index);
 290            super_method->access_flags().print_on(tty);
 291            if (super_method->is_default_method()) {
 292              tty->print("default ");
 293            }
 294            tty->print("overriders flags: ");
 295            target_method->access_flags().print_on(tty);
 296            if (target_method->is_default_method()) {
 297              tty->print("default ");
 298            }
 299         }
 300 #endif /*PRODUCT*/
 301         break; // return found superk
 302       }
 303     } else  {
 304       // super class has no vtable entry here, stop transitive search
 305       superk = (InstanceKlass*)NULL;
 306       break;
 307     }
 308     // if no override found yet, continue to search up
 309     superk = InstanceKlass::cast(superk->super());
 310   }
 311 
 312   return superk;
 313 }
 314 
 315 // Update child's copy of super vtable for overrides
 316 // OR return true if a new vtable entry is required.
 317 // Only called for InstanceKlass's, i.e. not for arrays
 318 // If that changed, could not use _klass as handle for klass
 319 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method,
 320                                           int super_vtable_len, int default_index,
 321                                           bool checkconstraints, TRAPS) {
 322   ResourceMark rm;
 323   bool allocate_new = true;
 324   assert(klass->oop_is_instance(), "must be InstanceKlass");
 325 
 326   Array<int>* def_vtable_indices = NULL;
 327   bool is_default = false;
 328   // default methods are concrete methods in superinterfaces which are added to the vtable
 329   // with their real method_holder
 330   // Since vtable and itable indices share the same storage, don't touch
 331   // the default method's real vtable/itable index
 332   // default_vtable_indices stores the vtable value relative to this inheritor
 333   if (default_index >= 0 ) {
 334     is_default = true;
 335     def_vtable_indices = klass->default_vtable_indices();
 336     assert(def_vtable_indices != NULL, "def vtable alloc?");
 337     assert(default_index <= def_vtable_indices->length(), "def vtable len?");
 338   } else {
 339     assert(klass == target_method()->method_holder(), "caller resp.");
 340     // Initialize the method's vtable index to "nonvirtual".
 341     // If we allocate a vtable entry, we will update it to a non-negative number.
 342     target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
 343   }
 344 
 345   // Static and <init> methods are never in
 346   if (target_method()->is_static() || target_method()->name() ==  vmSymbols::object_initializer_name()) {
 347     return false;
 348   }
 349 
 350   if (target_method->is_final_method(klass->access_flags())) {
 351     // a final method never needs a new entry; final methods can be statically
 352     // resolved and they have to be present in the vtable only if they override
 353     // a super's method, in which case they re-use its entry
 354     allocate_new = false;
 355   } else if (klass->is_interface()) {
 356     allocate_new = false;  // see note below in needs_new_vtable_entry
 357     // An interface never allocates new vtable slots, only inherits old ones.
 358     // This method will either be assigned its own itable index later,
 359     // or be assigned an inherited vtable index in the loop below.
 360     // default methods inherited by classes store their vtable indices
 361     // in the inheritor's default_vtable_indices
 362     // default methods inherited by interfaces may already have a
 363     // valid itable index, if so, don't change it
 364     // overpass methods in an interface will be assigned an itable index later
 365     // by an inheriting class
 366     if (!is_default || !target_method()->has_itable_index()) {
 367       target_method()->set_vtable_index(Method::pending_itable_index);
 368     }
 369   }
 370 
 371   // we need a new entry if there is no superclass
 372   if (klass->super() == NULL) {
 373     return allocate_new;
 374   }
 375 
 376   // private methods in classes always have a new entry in the vtable
 377   // specification interpretation since classic has
 378   // private methods not overriding
 379   // JDK8 adds private methods in interfaces which require invokespecial
 380   if (target_method()->is_private()) {
 381     return allocate_new;
 382   }
 383 
 384   // search through the vtable and update overridden entries
 385   // Since check_signature_loaders acquires SystemDictionary_lock
 386   // which can block for gc, once we are in this loop, use handles
 387   // For classfiles built with >= jdk7, we now look for transitive overrides
 388 
 389   Symbol* name = target_method()->name();
 390   Symbol* signature = target_method()->signature();
 391 
 392   KlassHandle target_klass(THREAD, target_method()->method_holder());
 393   if (target_klass == NULL) {
 394     target_klass = _klass;
 395   }
 396 
 397   Handle target_loader(THREAD, target_klass->class_loader());
 398 
 399   Symbol* target_classname = target_klass->name();
 400   for(int i = 0; i < super_vtable_len; i++) {
 401     Method* super_method = method_at(i);
 402     // Check if method name matches
 403     if (super_method->name() == name && super_method->signature() == signature) {
 404 
 405       // get super_klass for method_holder for the found method
 406       InstanceKlass* super_klass =  super_method->method_holder();
 407 
 408       if (is_default
 409           || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
 410           || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
 411           && ((super_klass = find_transitive_override(super_klass,
 412                              target_method, i, target_loader,
 413                              target_classname, THREAD))
 414                              != (InstanceKlass*)NULL))))
 415         {
 416         // Package private methods always need a new entry to root their own
 417         // overriding. They may also override other methods.
 418         if (!target_method()->is_package_private()) {
 419           allocate_new = false;
 420         }
 421 
 422         if (checkconstraints) {
 423         // Override vtable entry if passes loader constraint check
 424         // if loader constraint checking requested
 425         // No need to visit his super, since he and his super
 426         // have already made any needed loader constraints.
 427         // Since loader constraints are transitive, it is enough
 428         // to link to the first super, and we get all the others.
 429           Handle super_loader(THREAD, super_klass->class_loader());
 430 
 431           if (target_loader() != super_loader()) {
 432             ResourceMark rm(THREAD);
 433             Symbol* failed_type_symbol =
 434               SystemDictionary::check_signature_loaders(signature, target_loader,
 435                                                         super_loader, true,
 436                                                         CHECK_(false));
 437             if (failed_type_symbol != NULL) {
 438               const char* msg = "loader constraint violation: when resolving "
 439                 "overridden method \"%s\" the class loader (instance"
 440                 " of %s) of the current class, %s, and its superclass loader "
 441                 "(instance of %s), have different Class objects for the type "
 442                 "%s used in the signature";
 443               char* sig = target_method()->name_and_sig_as_C_string();
 444               const char* loader1 = SystemDictionary::loader_name(target_loader());
 445               char* current = target_klass->name()->as_C_string();
 446               const char* loader2 = SystemDictionary::loader_name(super_loader());
 447               char* failed_type_name = failed_type_symbol->as_C_string();
 448               size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
 449                 strlen(current) + strlen(loader2) + strlen(failed_type_name);
 450               char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
 451               jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
 452                            failed_type_name);
 453               THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
 454             }
 455           }
 456        }
 457 
 458        put_method_at(target_method(), i);
 459        if (!is_default) {
 460          target_method()->set_vtable_index(i);
 461        } else {
 462          if (def_vtable_indices != NULL) {
 463            def_vtable_indices->at_put(default_index, i);
 464          }
 465          assert(super_method->is_default_method() || super_method->is_overpass()
 466                 || super_method->is_abstract(), "default override error");
 467        }
 468 
 469 
 470 #ifndef PRODUCT
 471         if (PrintVtables && Verbose) {
 472           ResourceMark rm(THREAD);
 473           char* sig = target_method()->name_and_sig_as_C_string();
 474           tty->print("overriding with %s::%s index %d, original flags: ",
 475            target_klass->internal_name(), sig, i);
 476            super_method->access_flags().print_on(tty);
 477            if (super_method->is_default_method()) {
 478              tty->print("default ");
 479            }
 480            if (super_method->is_overpass()) {
 481              tty->print("overpass");
 482            }
 483            tty->print("overriders flags: ");
 484            target_method->access_flags().print_on(tty);
 485            if (target_method->is_default_method()) {
 486              tty->print("default ");
 487            }
 488            if (target_method->is_overpass()) {
 489              tty->print("overpass");
 490            }
 491            tty->cr();
 492         }
 493 #endif /*PRODUCT*/
 494       } else {
 495         // allocate_new = true; default. We might override one entry,
 496         // but not override another. Once we override one, not need new
 497 #ifndef PRODUCT
 498         if (PrintVtables && Verbose) {
 499           ResourceMark rm(THREAD);
 500           char* sig = target_method()->name_and_sig_as_C_string();
 501           tty->print("NOT overriding with %s::%s index %d, original flags: ",
 502            target_klass->internal_name(), sig,i);
 503            super_method->access_flags().print_on(tty);
 504            if (super_method->is_default_method()) {
 505              tty->print("default ");
 506            }
 507            if (super_method->is_overpass()) {
 508              tty->print("overpass");
 509            }
 510            tty->print("overriders flags: ");
 511            target_method->access_flags().print_on(tty);
 512            if (target_method->is_default_method()) {
 513              tty->print("default ");
 514            }
 515            if (target_method->is_overpass()) {
 516              tty->print("overpass");
 517            }
 518            tty->cr();
 519         }
 520 #endif /*PRODUCT*/
 521       }
 522     }
 523   }
 524   return allocate_new;
 525 }
 526 
 527 void klassVtable::put_method_at(Method* m, int index) {
 528 #ifndef PRODUCT
 529   if (PrintVtables && Verbose) {
 530     ResourceMark rm;
 531     const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
 532     tty->print("adding %s at index %d, flags: ", sig, index);
 533     if (m != NULL) {
 534       m->access_flags().print_on(tty);
 535       if (m->is_default_method()) {
 536         tty->print("default ");
 537       }
 538       if (m->is_overpass()) {
 539         tty->print("overpass");
 540       }
 541     }
 542     tty->cr();
 543   }
 544 #endif
 545   table()[index].set(m);
 546 }
 547 
 548 // Find out if a method "m" with superclass "super", loader "classloader" and
 549 // name "classname" needs a new vtable entry.  Let P be a class package defined
 550 // by "classloader" and "classname".
 551 // NOTE: The logic used here is very similar to the one used for computing
 552 // the vtables indices for a method. We cannot directly use that function because,
 553 // we allocate the InstanceKlass at load time, and that requires that the
 554 // superclass has been loaded.
 555 // However, the vtable entries are filled in at link time, and therefore
 556 // the superclass' vtable may not yet have been filled in.
 557 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
 558                                          Klass* super,
 559                                          Handle classloader,
 560                                          Symbol* classname,
 561                                          AccessFlags class_flags,
 562                                          TRAPS) {
 563   if (class_flags.is_interface()) {
 564     // Interfaces do not use vtables, except for java.lang.Object methods,
 565     // so there is no point to assigning
 566     // a vtable index to any of their local methods.  If we refrain from doing this,
 567     // we can use Method::_vtable_index to hold the itable index
 568     return false;
 569   }
 570 
 571   if (target_method->is_final_method(class_flags) ||
 572       // a final method never needs a new entry; final methods can be statically
 573       // resolved and they have to be present in the vtable only if they override
 574       // a super's method, in which case they re-use its entry
 575       (target_method()->is_static()) ||
 576       // static methods don't need to be in vtable
 577       (target_method()->name() ==  vmSymbols::object_initializer_name())
 578       // <init> is never called dynamically-bound
 579       ) {
 580     return false;
 581   }
 582 
 583   // Concrete interface methods do not need new entries, they override
 584   // abstract method entries using default inheritance rules
 585   if (target_method()->method_holder() != NULL &&
 586       target_method()->method_holder()->is_interface()  &&
 587       !target_method()->is_abstract() ) {
 588     return false;
 589   }
 590 
 591   // we need a new entry if there is no superclass
 592   if (super == NULL) {
 593     return true;
 594   }
 595 
 596   // private methods in classes always have a new entry in the vtable
 597   // specification interpretation since classic has
 598   // private methods not overriding
 599   // JDK8 adds private  methods in interfaces which require invokespecial
 600   if (target_method()->is_private()) {
 601     return true;
 602   }
 603 
 604   // Package private methods always need a new entry to root their own
 605   // overriding. This allows transitive overriding to work.
 606   if (target_method()->is_package_private()) {
 607     return true;
 608   }
 609 
 610   // search through the super class hierarchy to see if we need
 611   // a new entry
 612   ResourceMark rm;
 613   Symbol* name = target_method()->name();
 614   Symbol* signature = target_method()->signature();
 615   Klass* k = super;
 616   Method* super_method = NULL;
 617   InstanceKlass *holder = NULL;
 618   Method* recheck_method =  NULL;
 619   while (k != NULL) {
 620     // lookup through the hierarchy for a method with matching name and sign.
 621     super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
 622     if (super_method == NULL) {
 623       break; // we still have to search for a matching miranda method
 624     }
 625     // get the class holding the matching method
 626     // make sure you use that class for is_override
 627     InstanceKlass* superk = super_method->method_holder();
 628     // we want only instance method matches
 629     // pretend private methods are not in the super vtable
 630     // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
 631     // ignore private, c.m pub does override a.m pub
 632     // For classes that were not javac'd together, we also do transitive overriding around
 633     // methods that have less accessibility
 634     if ((!super_method->is_static()) &&
 635        (!super_method->is_private())) {
 636       if (superk->is_override(super_method, classloader, classname, THREAD)) {
 637         return false;
 638       // else keep looking for transitive overrides
 639       }
 640     }
 641 
 642     // Start with lookup result and continue to search up
 643     k = superk->super(); // haven't found an override match yet; continue to look
 644   }
 645 
 646   // if the target method is public or protected it may have a matching
 647   // miranda method in the super, whose entry it should re-use.
 648   // Actually, to handle cases that javac would not generate, we need
 649   // this check for all access permissions.
 650   InstanceKlass *sk = InstanceKlass::cast(super);
 651   if (sk->has_miranda_methods()) {
 652     if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
 653       return false;  // found a matching miranda; we do not need a new entry
 654     }
 655   }
 656   return true; // found no match; we need a new entry
 657 }
 658 
 659 // Support for miranda methods
 660 
 661 // get the vtable index of a miranda method with matching "name" and "signature"
 662 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
 663   // search from the bottom, might be faster
 664   for (int i = (length() - 1); i >= 0; i--) {
 665     Method* m = table()[i].method();
 666     if (is_miranda_entry_at(i) &&
 667         m->name() == name && m->signature() == signature) {
 668       return i;
 669     }
 670   }
 671   return Method::invalid_vtable_index;
 672 }
 673 
 674 // check if an entry at an index is miranda
 675 // requires that method m at entry be declared ("held") by an interface.
 676 bool klassVtable::is_miranda_entry_at(int i) {
 677   Method* m = method_at(i);
 678   Klass* method_holder = m->method_holder();
 679   InstanceKlass *mhk = InstanceKlass::cast(method_holder);
 680 
 681   // miranda methods are public abstract instance interface methods in a class's vtable
 682   if (mhk->is_interface()) {
 683     assert(m->is_public(), "should be public");
 684     assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
 685     // the search could find a miranda or a default method
 686     if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
 687       return true;
 688     }
 689   }
 690   return false;
 691 }
 692 
 693 // check if a method is a miranda method, given a class's methods table,
 694 // its default_method table  and its super
 695 // Miranda methods are calculated twice:
 696 // first: before vtable size calculation: including abstract and default
 697 // This is seen by default method creation
 698 // Second: recalculated during vtable initialization: only abstract
 699 // This is seen by link resolution and selection.
 700 // "miranda" means not static, not defined by this class.
 701 // private methods in interfaces do not belong in the miranda list.
 702 // the caller must make sure that the method belongs to an interface implemented by the class
 703 // Miranda methods only include public interface instance methods
 704 // Not private methods, not static methods, not default == concrete abstract
 705 // Miranda methods also do not include overpass methods in interfaces
 706 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
 707                              Array<Method*>* default_methods, Klass* super) {
 708   if (m->is_static() || m->is_private() || m->is_overpass()) {
 709     return false;
 710   }
 711   Symbol* name = m->name();
 712   Symbol* signature = m->signature();
 713 
 714   if (InstanceKlass::find_instance_method(class_methods, name, signature) == NULL) {
 715     // did not find it in the method table of the current class
 716     if ((default_methods == NULL) ||
 717         InstanceKlass::find_method(default_methods, name, signature) == NULL) {
 718       if (super == NULL) {
 719         // super doesn't exist
 720         return true;
 721       }
 722 
 723       Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature);
 724       while (mo != NULL && mo->access_flags().is_static()
 725              && mo->method_holder() != NULL
 726              && mo->method_holder()->super() != NULL)
 727       {
 728          mo = mo->method_holder()->super()->uncached_lookup_method(name, signature, Klass::find_overpass);
 729       }
 730       if (mo == NULL || mo->access_flags().is_private() ) {
 731         // super class hierarchy does not implement it or protection is different
 732         return true;
 733       }
 734     }
 735   }
 736 
 737   return false;
 738 }
 739 
 740 // Scans current_interface_methods for miranda methods that do not
 741 // already appear in new_mirandas, or default methods,  and are also not defined-and-non-private
 742 // in super (superclass).  These mirandas are added to all_mirandas if it is
 743 // not null; in addition, those that are not duplicates of miranda methods
 744 // inherited by super from its interfaces are added to new_mirandas.
 745 // Thus, new_mirandas will be the set of mirandas that this class introduces,
 746 // all_mirandas will be the set of all mirandas applicable to this class
 747 // including all defined in superclasses.
 748 void klassVtable::add_new_mirandas_to_lists(
 749     GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
 750     Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
 751     Array<Method*>* default_methods, Klass* super) {
 752 
 753   // iterate thru the current interface's method to see if it a miranda
 754   int num_methods = current_interface_methods->length();
 755   for (int i = 0; i < num_methods; i++) {
 756     Method* im = current_interface_methods->at(i);
 757     bool is_duplicate = false;
 758     int num_of_current_mirandas = new_mirandas->length();
 759     // check for duplicate mirandas in different interfaces we implement
 760     for (int j = 0; j < num_of_current_mirandas; j++) {
 761       Method* miranda = new_mirandas->at(j);
 762       if ((im->name() == miranda->name()) &&
 763           (im->signature() == miranda->signature())) {
 764         is_duplicate = true;
 765         break;
 766       }
 767     }
 768 
 769     if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
 770       if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all?
 771         InstanceKlass *sk = InstanceKlass::cast(super);
 772         // check if it is a duplicate of a super's miranda
 773         if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
 774           new_mirandas->append(im);
 775         }
 776         if (all_mirandas != NULL) {
 777           all_mirandas->append(im);
 778         }
 779       }
 780     }
 781   }
 782 }
 783 
 784 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
 785                                GrowableArray<Method*>* all_mirandas,
 786                                Klass* super, Array<Method*>* class_methods,
 787                                Array<Method*>* default_methods,
 788                                Array<Klass*>* local_interfaces) {
 789   assert((new_mirandas->length() == 0) , "current mirandas must be 0");
 790 
 791   // iterate thru the local interfaces looking for a miranda
 792   int num_local_ifs = local_interfaces->length();
 793   for (int i = 0; i < num_local_ifs; i++) {
 794     InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
 795     add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 796                               ik->methods(), class_methods,
 797                               default_methods, super);
 798     // iterate thru each local's super interfaces
 799     Array<Klass*>* super_ifs = ik->transitive_interfaces();
 800     int num_super_ifs = super_ifs->length();
 801     for (int j = 0; j < num_super_ifs; j++) {
 802       InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
 803       add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 804                                 sik->methods(), class_methods,
 805                                 default_methods, super);
 806     }
 807   }
 808 }
 809 
 810 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
 811 // and append them into the vtable starting at index initialized,
 812 // return the new value of initialized.
 813 // Miranda methods use vtable entries, but do not get assigned a vtable_index
 814 // The vtable_index is discovered by searching from the end of the vtable
 815 int klassVtable::fill_in_mirandas(int initialized) {
 816   GrowableArray<Method*> mirandas(20);
 817   get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
 818                ik()->default_methods(), ik()->local_interfaces());
 819   for (int i = 0; i < mirandas.length(); i++) {
 820     if (PrintVtables && Verbose) {
 821       Method* meth = mirandas.at(i);
 822       ResourceMark rm(Thread::current());
 823       if (meth != NULL) {
 824         char* sig = meth->name_and_sig_as_C_string();
 825         tty->print("fill in mirandas with %s index %d, flags: ",
 826           sig, initialized);
 827         meth->access_flags().print_on(tty);
 828         if (meth->is_default_method()) {
 829           tty->print("default ");
 830         }
 831         tty->cr();
 832       }
 833     }
 834     put_method_at(mirandas.at(i), initialized);
 835     ++initialized;
 836   }
 837   return initialized;
 838 }
 839 
 840 // Copy this class's vtable to the vtable beginning at start.
 841 // Used to copy superclass vtable to prefix of subclass's vtable.
 842 void klassVtable::copy_vtable_to(vtableEntry* start) {
 843   Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
 844 }
 845 
 846 #if INCLUDE_JVMTI
 847 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
 848   // If old_method is default, find this vtable index in default_vtable_indices
 849   // and replace that method in the _default_methods list
 850   bool updated = false;
 851 
 852   Array<Method*>* default_methods = ik()->default_methods();
 853   if (default_methods != NULL) {
 854     int len = default_methods->length();
 855     for (int idx = 0; idx < len; idx++) {
 856       if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
 857         if (default_methods->at(idx) == old_method) {
 858           default_methods->at_put(idx, new_method);
 859           updated = true;
 860         }
 861         break;
 862       }
 863     }
 864   }
 865   return updated;
 866 }
 867 
 868 // search the vtable for uses of either obsolete or EMCP methods
 869 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
 870 
 871   for (int index = 0; index < length(); index++) {
 872     Method* old_method = unchecked_method_at(index);
 873     if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
 874       continue; // skip uninteresting entries
 875     }
 876     assert(!old_method->is_deleted(), "vtable methods may not be deleted");
 877     Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
 878     assert(new_method != NULL, "method_with_idnum() should not be NULL");
 879     if (old_method == new_method) {
 880       continue;
 881     }
 882     put_method_at(new_method, index);
 883     // For default methods, need to update the _default_methods array
 884     // which can only have one method entry for a given signature
 885     bool updated_default = false;
 886     if (old_method->is_default_method()) {
 887       updated_default = adjust_default_method(index, old_method, new_method);
 888     }
 889 
 890     if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
 891       if (!(*trace_name_printed)) {
 892         // RC_TRACE_MESG macro has an embedded ResourceMark
 893         RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s",
 894                        klass()->external_name(),
 895                        old_method->method_holder()->external_name()));
 896         *trace_name_printed = true;
 897       }
 898       // RC_TRACE macro has an embedded ResourceMark
 899       RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s",
 900                             new_method->name()->as_C_string(),
 901                             new_method->signature()->as_C_string(),
 902                             updated_default ? "true" : "false"));
 903     }
 904   }
 905 }
 906 
 907 // a vtable should never contain old or obsolete methods
 908 bool klassVtable::check_no_old_or_obsolete_entries() {
 909   for (int i = 0; i < length(); i++) {
 910     Method* m = unchecked_method_at(i);
 911     if (m != NULL &&
 912         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
 913       return false;
 914     }
 915   }
 916   return true;
 917 }
 918 
 919 void klassVtable::dump_vtable() {
 920   tty->print_cr("vtable dump --");
 921   for (int i = 0; i < length(); i++) {
 922     Method* m = unchecked_method_at(i);
 923     if (m != NULL) {
 924       tty->print("      (%5d)  ", i);
 925       m->access_flags().print_on(tty);
 926       if (m->is_default_method()) {
 927         tty->print("default ");
 928       }
 929       if (m->is_overpass()) {
 930         tty->print("overpass");
 931       }
 932       tty->print(" --  ");
 933       m->print_name(tty);
 934       tty->cr();
 935     }
 936   }
 937 }
 938 #endif // INCLUDE_JVMTI
 939 
 940 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
 941 void klassVtable::clear_vtable() {
 942   for (int i = 0; i < _length; i++) table()[i].clear();
 943 }
 944 
 945 bool klassVtable::is_initialized() {
 946   return _length == 0 || table()[0].method() != NULL;
 947 }
 948 
 949 //-----------------------------------------------------------------------------------------
 950 // Itable code
 951 
 952 // Initialize a itableMethodEntry
 953 void itableMethodEntry::initialize(Method* m) {
 954   if (m == NULL) return;
 955 
 956   _method = m;
 957 }
 958 
 959 klassItable::klassItable(instanceKlassHandle klass) {
 960   _klass = klass;
 961 
 962   if (klass->itable_length() > 0) {
 963     itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
 964     if (offset_entry  != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
 965       // First offset entry points to the first method_entry
 966       intptr_t* method_entry  = (intptr_t *)(((address)klass()) + offset_entry->offset());
 967       intptr_t* end         = klass->end_of_itable();
 968 
 969       _table_offset      = (intptr_t*)offset_entry - (intptr_t*)klass();
 970       _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
 971       _size_method_table = (end - method_entry)                  / itableMethodEntry::size();
 972       assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
 973       return;
 974     }
 975   }
 976 
 977   // The length of the itable was either zero, or it has not yet been initialized.
 978   _table_offset      = 0;
 979   _size_offset_table = 0;
 980   _size_method_table = 0;
 981 }
 982 
 983 static int initialize_count = 0;
 984 
 985 // Initialization
 986 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
 987   if (_klass->is_interface()) {
 988     // This needs to go after vtable indices are assigned but
 989     // before implementors need to know the number of itable indices.
 990     assign_itable_indices_for_interface(_klass());
 991   }
 992 
 993   // Cannot be setup doing bootstrapping, interfaces don't have
 994   // itables, and klass with only ones entry have empty itables
 995   if (Universe::is_bootstrapping() ||
 996       _klass->is_interface() ||
 997       _klass->itable_length() == itableOffsetEntry::size()) return;
 998 
 999   // There's alway an extra itable entry so we can null-terminate it.
1000   guarantee(size_offset_table() >= 1, "too small");
1001   int num_interfaces = size_offset_table() - 1;
1002   if (num_interfaces > 0) {
1003     if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count,
1004                                     _klass->name()->as_C_string());
1005 
1006 
1007     // Iterate through all interfaces
1008     int i;
1009     for(i = 0; i < num_interfaces; i++) {
1010       itableOffsetEntry* ioe = offset_entry(i);
1011       HandleMark hm(THREAD);
1012       KlassHandle interf_h (THREAD, ioe->interface_klass());
1013       assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
1014       initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
1015     }
1016 
1017   }
1018   // Check that the last entry is empty
1019   itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1020   guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1021 }
1022 
1023 
1024 inline bool interface_method_needs_itable_index(Method* m) {
1025   if (m->is_static())           return false;   // e.g., Stream.empty
1026   if (m->is_initializer())      return false;   // <init> or <clinit>
1027   // If an interface redeclares a method from java.lang.Object,
1028   // it should already have a vtable index, don't touch it.
1029   // e.g., CharSequence.toString (from initialize_vtable)
1030   // if (m->has_vtable_index())  return false; // NO!
1031   return true;
1032 }
1033 
1034 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1035   // an interface does not have an itable, but its methods need to be numbered
1036   if (TraceItables) tty->print_cr("%3d: Initializing itable for interface %s", ++initialize_count,
1037                                   klass->name()->as_C_string());
1038   Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1039   int nof_methods = methods->length();
1040   int ime_num = 0;
1041   for (int i = 0; i < nof_methods; i++) {
1042     Method* m = methods->at(i);
1043     if (interface_method_needs_itable_index(m)) {
1044       assert(!m->is_final_method(), "no final interface methods");
1045       // If m is already assigned a vtable index, do not disturb it.
1046       if (TraceItables && Verbose) {
1047         ResourceMark rm;
1048         const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
1049         if (m->has_vtable_index()) {
1050           tty->print("itable index %d for method: %s, flags: ", m->vtable_index(), sig);
1051         } else {
1052           tty->print("itable index %d for method: %s, flags: ", ime_num, sig);
1053         }
1054         if (m != NULL) {
1055           m->access_flags().print_on(tty);
1056           if (m->is_default_method()) {
1057             tty->print("default ");
1058           }
1059           if (m->is_overpass()) {
1060             tty->print("overpass");
1061           }
1062         }
1063         tty->cr();
1064       }
1065       if (!m->has_vtable_index()) {
1066         assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable");
1067         m->set_itable_index(ime_num);
1068         // Progress to next itable entry
1069         ime_num++;
1070       }
1071     }
1072   }
1073   assert(ime_num == method_count_for_interface(klass), "proper sizing");
1074   return ime_num;
1075 }
1076 
1077 int klassItable::method_count_for_interface(Klass* interf) {
1078   assert(interf->oop_is_instance(), "must be");
1079   assert(interf->is_interface(), "must be");
1080   Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1081   int nof_methods = methods->length();
1082   while (nof_methods > 0) {
1083     Method* m = methods->at(nof_methods-1);
1084     if (m->has_itable_index()) {
1085       int length = m->itable_index() + 1;
1086 #ifdef ASSERT
1087       while (nof_methods = 0) {
1088         m = methods->at(--nof_methods);
1089         assert(!m->has_itable_index() || m->itable_index() < length, "");
1090       }
1091 #endif //ASSERT
1092       return length;  // return the rightmost itable index, plus one
1093     }
1094     nof_methods -= 1;
1095   }
1096   // no methods have itable indices
1097   return 0;
1098 }
1099 
1100 
1101 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
1102   Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();
1103   int nof_methods = methods->length();
1104   HandleMark hm;
1105   assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
1106   Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader());
1107 
1108   int ime_count = method_count_for_interface(interf_h());
1109   for (int i = 0; i < nof_methods; i++) {
1110     Method* m = methods->at(i);
1111     methodHandle target;
1112     if (m->has_itable_index()) {
1113       // This search must match the runtime resolution, i.e. selection search for invokeinterface
1114       // to correctly enforce loader constraints for interface method inheritance
1115       LinkResolver::lookup_instance_method_in_klasses(target, _klass, m->name(), m->signature(), CHECK);
1116     }
1117     if (target == NULL || !target->is_public() || target->is_abstract()) {
1118       // Entry does not resolve. Leave it empty for AbstractMethodError.
1119         if (!(target == NULL) && !target->is_public()) {
1120           // Stuff an IllegalAccessError throwing method in there instead.
1121           itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()].
1122               initialize(Universe::throw_illegal_access_error());
1123         }
1124     } else {
1125       // Entry did resolve, check loader constraints before initializing
1126       // if checkconstraints requested
1127       if (checkconstraints) {
1128         Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1129         if (method_holder_loader() != interface_loader()) {
1130           ResourceMark rm(THREAD);
1131           Symbol* failed_type_symbol =
1132             SystemDictionary::check_signature_loaders(m->signature(),
1133                                                       method_holder_loader,
1134                                                       interface_loader,
1135                                                       true, CHECK);
1136           if (failed_type_symbol != NULL) {
1137             const char* msg = "loader constraint violation in interface "
1138               "itable initialization: when resolving method \"%s\" the class"
1139               " loader (instance of %s) of the current class, %s, "
1140               "and the class loader (instance of %s) for interface "
1141               "%s have different Class objects for the type %s "
1142               "used in the signature";
1143             char* sig = target()->name_and_sig_as_C_string();
1144             const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
1145             char* current = _klass->name()->as_C_string();
1146             const char* loader2 = SystemDictionary::loader_name(interface_loader());
1147             char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string();
1148             char* failed_type_name = failed_type_symbol->as_C_string();
1149             size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
1150               strlen(current) + strlen(loader2) + strlen(iface) +
1151               strlen(failed_type_name);
1152             char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1153             jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
1154                          iface, failed_type_name);
1155             THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1156           }
1157         }
1158       }
1159 
1160       // ime may have moved during GC so recalculate address
1161       int ime_num = m->itable_index();
1162       assert(ime_num < ime_count, "oob");
1163       itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target());
1164       if (TraceItables && Verbose) {
1165         ResourceMark rm(THREAD);
1166         if (target() != NULL) {
1167           char* sig = target()->name_and_sig_as_C_string();
1168           tty->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1169                     interf_h()->internal_name(), ime_num, sig,
1170                     target()->method_holder()->internal_name());
1171           tty->print("target_method flags: ");
1172           target()->access_flags().print_on(tty);
1173           if (target()->is_default_method()) {
1174             tty->print("default ");
1175           }
1176           tty->cr();
1177         }
1178       }
1179     }
1180   }
1181 }
1182 
1183 // Update entry for specific Method*
1184 void klassItable::initialize_with_method(Method* m) {
1185   itableMethodEntry* ime = method_entry(0);
1186   for(int i = 0; i < _size_method_table; i++) {
1187     if (ime->method() == m) {
1188       ime->initialize(m);
1189     }
1190     ime++;
1191   }
1192 }
1193 
1194 #if INCLUDE_JVMTI
1195 // search the itable for uses of either obsolete or EMCP methods
1196 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1197 
1198   itableMethodEntry* ime = method_entry(0);
1199   for (int i = 0; i < _size_method_table; i++, ime++) {
1200     Method* old_method = ime->method();
1201     if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1202       continue; // skip uninteresting entries
1203     }
1204     assert(!old_method->is_deleted(), "itable methods may not be deleted");
1205     Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1206     assert(new_method != NULL, "method_with_idnum() should not be NULL");
1207     if (old_method == new_method) {
1208       continue;
1209     }
1210     ime->initialize(new_method);
1211 
1212     if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
1213       if (!(*trace_name_printed)) {
1214         // RC_TRACE_MESG macro has an embedded ResourceMark
1215         RC_TRACE_MESG(("adjust: name=%s",
1216           old_method->method_holder()->external_name()));
1217         *trace_name_printed = true;
1218       }
1219       // RC_TRACE macro has an embedded ResourceMark
1220       RC_TRACE(0x00200000, ("itable method update: %s(%s)",
1221         new_method->name()->as_C_string(),
1222         new_method->signature()->as_C_string()));
1223     }
1224   }
1225 }
1226 
1227 // an itable should never contain old or obsolete methods
1228 bool klassItable::check_no_old_or_obsolete_entries() {
1229   itableMethodEntry* ime = method_entry(0);
1230   for (int i = 0; i < _size_method_table; i++) {
1231     Method* m = ime->method();
1232     if (m != NULL &&
1233         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1234       return false;
1235     }
1236     ime++;
1237   }
1238   return true;
1239 }
1240 
1241 void klassItable::dump_itable() {
1242   itableMethodEntry* ime = method_entry(0);
1243   tty->print_cr("itable dump --");
1244   for (int i = 0; i < _size_method_table; i++) {
1245     Method* m = ime->method();
1246     if (m != NULL) {
1247       tty->print("      (%5d)  ", i);
1248       m->access_flags().print_on(tty);
1249       if (m->is_default_method()) {
1250         tty->print("default ");
1251       }
1252       tty->print(" --  ");
1253       m->print_name(tty);
1254       tty->cr();
1255     }
1256     ime++;
1257   }
1258 }
1259 #endif // INCLUDE_JVMTI
1260 
1261 
1262 // Setup
1263 class InterfaceVisiterClosure : public StackObj {
1264  public:
1265   virtual void doit(Klass* intf, int method_count) = 0;
1266 };
1267 
1268 // Visit all interfaces with at least one itable method
1269 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1270   // Handle array argument
1271   for(int i = 0; i < transitive_intf->length(); i++) {
1272     Klass* intf = transitive_intf->at(i);
1273     assert(intf->is_interface(), "sanity check");
1274 
1275     // Find no. of itable methods
1276     int method_count = 0;
1277     // method_count = klassItable::method_count_for_interface(intf);
1278     Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1279     if (methods->length() > 0) {
1280       for (int i = methods->length(); --i >= 0; ) {
1281         if (interface_method_needs_itable_index(methods->at(i))) {
1282           method_count++;
1283         }
1284       }
1285     }
1286 
1287     // Only count interfaces with at least one method
1288     if (method_count > 0) {
1289       blk->doit(intf, method_count);
1290     }
1291   }
1292 }
1293 
1294 class CountInterfacesClosure : public InterfaceVisiterClosure {
1295  private:
1296   int _nof_methods;
1297   int _nof_interfaces;
1298  public:
1299    CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1300 
1301    int nof_methods() const    { return _nof_methods; }
1302    int nof_interfaces() const { return _nof_interfaces; }
1303 
1304    void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1305 };
1306 
1307 class SetupItableClosure : public InterfaceVisiterClosure  {
1308  private:
1309   itableOffsetEntry* _offset_entry;
1310   itableMethodEntry* _method_entry;
1311   address            _klass_begin;
1312  public:
1313   SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1314     _klass_begin  = klass_begin;
1315     _offset_entry = offset_entry;
1316     _method_entry = method_entry;
1317   }
1318 
1319   itableMethodEntry* method_entry() const { return _method_entry; }
1320 
1321   void doit(Klass* intf, int method_count) {
1322     int offset = ((address)_method_entry) - _klass_begin;
1323     _offset_entry->initialize(intf, offset);
1324     _offset_entry++;
1325     _method_entry += method_count;
1326   }
1327 };
1328 
1329 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1330   // Count no of interfaces and total number of interface methods
1331   CountInterfacesClosure cic;
1332   visit_all_interfaces(transitive_interfaces, &cic);
1333 
1334   // There's alway an extra itable entry so we can null-terminate it.
1335   int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1336 
1337   // Statistics
1338   update_stats(itable_size * HeapWordSize);
1339 
1340   return itable_size;
1341 }
1342 
1343 
1344 // Fill out offset table and interface klasses into the itable space
1345 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
1346   if (klass->itable_length() == 0) return;
1347   assert(!klass->is_interface(), "Should have zero length itable");
1348 
1349   // Count no of interfaces and total number of interface methods
1350   CountInterfacesClosure cic;
1351   visit_all_interfaces(klass->transitive_interfaces(), &cic);
1352   int nof_methods    = cic.nof_methods();
1353   int nof_interfaces = cic.nof_interfaces();
1354 
1355   // Add one extra entry so we can null-terminate the table
1356   nof_interfaces++;
1357 
1358   assert(compute_itable_size(klass->transitive_interfaces()) ==
1359          calc_itable_size(nof_interfaces, nof_methods),
1360          "mismatch calculation of itable size");
1361 
1362   // Fill-out offset table
1363   itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1364   itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1365   intptr_t* end               = klass->end_of_itable();
1366   assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1367   assert((oop*)(end) == (oop*)(ime + nof_methods),                      "wrong offset calculation (2)");
1368 
1369   // Visit all interfaces and initialize itable offset table
1370   SetupItableClosure sic((address)klass(), ioe, ime);
1371   visit_all_interfaces(klass->transitive_interfaces(), &sic);
1372 
1373 #ifdef ASSERT
1374   ime  = sic.method_entry();
1375   oop* v = (oop*) klass->end_of_itable();
1376   assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1377 #endif
1378 }
1379 
1380 
1381 // inverse to itable_index
1382 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1383   assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1384   assert(intf->verify_itable_index(itable_index), "");
1385   Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1386 
1387   if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1388     return NULL;                // help caller defend against bad indices
1389 
1390   int index = itable_index;
1391   Method* m = methods->at(index);
1392   int index2 = -1;
1393   while (!m->has_itable_index() ||
1394          (index2 = m->itable_index()) != itable_index) {
1395     assert(index2 < itable_index, "monotonic");
1396     if (++index == methods->length())
1397       return NULL;
1398     m = methods->at(index);
1399   }
1400   assert(m->itable_index() == itable_index, "correct inverse");
1401 
1402   return m;
1403 }
1404 
1405 void klassVtable::verify(outputStream* st, bool forced) {
1406   // make sure table is initialized
1407   if (!Universe::is_fully_initialized()) return;
1408 #ifndef PRODUCT
1409   // avoid redundant verifies
1410   if (!forced && _verify_count == Universe::verify_count()) return;
1411   _verify_count = Universe::verify_count();
1412 #endif
1413   oop* end_of_obj = (oop*)_klass() + _klass()->size();
1414   oop* end_of_vtable = (oop *)&table()[_length];
1415   if (end_of_vtable > end_of_obj) {
1416     fatal(err_msg("klass %s: klass object too short (vtable extends beyond "
1417                   "end)", _klass->internal_name()));
1418   }
1419 
1420   for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1421   // verify consistency with superKlass vtable
1422   Klass* super = _klass->super();
1423   if (super != NULL) {
1424     InstanceKlass* sk = InstanceKlass::cast(super);
1425     klassVtable* vt = sk->vtable();
1426     for (int i = 0; i < vt->length(); i++) {
1427       verify_against(st, vt, i);
1428     }
1429   }
1430 }
1431 
1432 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1433   vtableEntry* vte = &vt->table()[index];
1434   if (vte->method()->name()      != table()[index].method()->name() ||
1435       vte->method()->signature() != table()[index].method()->signature()) {
1436     fatal("mismatched name/signature of vtable entries");
1437   }
1438 }
1439 
1440 #ifndef PRODUCT
1441 void klassVtable::print() {
1442   ResourceMark rm;
1443   tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1444   for (int i = 0; i < length(); i++) {
1445     table()[i].print();
1446     tty->cr();
1447   }
1448 }
1449 #endif
1450 
1451 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1452   NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1453   assert(method() != NULL, "must have set method");
1454   method()->verify();
1455   // we sub_type, because it could be a miranda method
1456   if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1457 #ifndef PRODUCT
1458     print();
1459 #endif
1460     fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
1461   }
1462 }
1463 
1464 #ifndef PRODUCT
1465 
1466 void vtableEntry::print() {
1467   ResourceMark rm;
1468   tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1469   if (Verbose) {
1470     tty->print("m %#lx ", (address)method());
1471   }
1472 }
1473 
1474 class VtableStats : AllStatic {
1475  public:
1476   static int no_klasses;                // # classes with vtables
1477   static int no_array_klasses;          // # array classes
1478   static int no_instance_klasses;       // # instanceKlasses
1479   static int sum_of_vtable_len;         // total # of vtable entries
1480   static int sum_of_array_vtable_len;   // total # of vtable entries in array klasses only
1481   static int fixed;                     // total fixed overhead in bytes
1482   static int filler;                    // overhead caused by filler bytes
1483   static int entries;                   // total bytes consumed by vtable entries
1484   static int array_entries;             // total bytes consumed by array vtable entries
1485 
1486   static void do_class(Klass* k) {
1487     Klass* kl = k;
1488     klassVtable* vt = kl->vtable();
1489     if (vt == NULL) return;
1490     no_klasses++;
1491     if (kl->oop_is_instance()) {
1492       no_instance_klasses++;
1493       kl->array_klasses_do(do_class);
1494     }
1495     if (kl->oop_is_array()) {
1496       no_array_klasses++;
1497       sum_of_array_vtable_len += vt->length();
1498     }
1499     sum_of_vtable_len += vt->length();
1500   }
1501 
1502   static void compute() {
1503     SystemDictionary::classes_do(do_class);
1504     fixed  = no_klasses * oopSize;      // vtable length
1505     // filler size is a conservative approximation
1506     filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1507     entries = sizeof(vtableEntry) * sum_of_vtable_len;
1508     array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1509   }
1510 };
1511 
1512 int VtableStats::no_klasses = 0;
1513 int VtableStats::no_array_klasses = 0;
1514 int VtableStats::no_instance_klasses = 0;
1515 int VtableStats::sum_of_vtable_len = 0;
1516 int VtableStats::sum_of_array_vtable_len = 0;
1517 int VtableStats::fixed = 0;
1518 int VtableStats::filler = 0;
1519 int VtableStats::entries = 0;
1520 int VtableStats::array_entries = 0;
1521 
1522 void klassVtable::print_statistics() {
1523   ResourceMark rm;
1524   HandleMark hm;
1525   VtableStats::compute();
1526   tty->print_cr("vtable statistics:");
1527   tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1528   int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1529   tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1530   tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1531   tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1532   tty->print_cr("%6d bytes total", total);
1533 }
1534 
1535 int  klassItable::_total_classes;   // Total no. of classes with itables
1536 long klassItable::_total_size;      // Total no. of bytes used for itables
1537 
1538 void klassItable::print_statistics() {
1539  tty->print_cr("itable statistics:");
1540  tty->print_cr("%6d classes with itables", _total_classes);
1541  tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes);
1542 }
1543 
1544 #endif // PRODUCT