1 /*
   2  * Copyright (c) 1997, 2014, 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 && !Universe::is_bootstrapping() &&
 104       vtable_length != Universe::base_vtable_size()) {
 105     // Someone is attempting to redefine java.lang.Object incorrectly.  The
 106     // only way this should happen is from
 107     // SystemDictionary::resolve_from_stream(), which will detect this later
 108     // and throw a security exception.  So don't assert here to let
 109     // the exception occur.
 110     vtable_length = Universe::base_vtable_size();
 111   }
 112   assert(super != NULL || vtable_length == Universe::base_vtable_size(),
 113          "bad vtable size for class Object");
 114   assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
 115   assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
 116 
 117   *vtable_length_ret = vtable_length;
 118 }
 119 
 120 int klassVtable::index_of(Method* m, int len) const {
 121   assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
 122   return m->vtable_index();
 123 }
 124 
 125 // Copy super class's vtable to the first part (prefix) of this class's vtable,
 126 // and return the number of entries copied.  Expects that 'super' is the Java
 127 // super class (arrays can have "array" super classes that must be skipped).
 128 int klassVtable::initialize_from_super(KlassHandle super) {
 129   if (super.is_null()) {
 130     return 0;
 131   } else {
 132     // copy methods from superKlass
 133     // can't inherit from array class, so must be InstanceKlass
 134     assert(super->oop_is_instance(), "must be instance klass");
 135     InstanceKlass* sk = (InstanceKlass*)super();
 136     klassVtable* superVtable = sk->vtable();
 137     assert(superVtable->length() <= _length, "vtable too short");
 138 #ifdef ASSERT
 139     superVtable->verify(tty, true);
 140 #endif
 141     superVtable->copy_vtable_to(table());
 142 #ifndef PRODUCT
 143     if (PrintVtables && Verbose) {
 144       ResourceMark rm;
 145       tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length);
 146     }
 147 #endif
 148     return superVtable->length();
 149   }
 150 }
 151 
 152 //
 153 // Revised lookup semantics   introduced 1.3 (Kestrel beta)
 154 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
 155 
 156   // Note:  Arrays can have intermediate array supers.  Use java_super to skip them.
 157   KlassHandle super (THREAD, klass()->java_super());
 158   int nofNewEntries = 0;
 159 
 160   if (PrintVtables && !klass()->oop_is_array()) {
 161     ResourceMark rm(THREAD);
 162     tty->print_cr("Initializing: %s", _klass->name()->as_C_string());
 163   }
 164 
 165 #ifdef ASSERT
 166   oop* end_of_obj = (oop*)_klass() + _klass()->size();
 167   oop* end_of_vtable = (oop*)&table()[_length];
 168   assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
 169 #endif
 170 
 171   if (Universe::is_bootstrapping()) {
 172     // just clear everything
 173     for (int i = 0; i < _length; i++) table()[i].clear();
 174     return;
 175   }
 176 
 177   int super_vtable_len = initialize_from_super(super);
 178   if (klass()->oop_is_array()) {
 179     assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
 180   } else {
 181     assert(_klass->oop_is_instance(), "must be InstanceKlass");
 182 
 183     Array<Method*>* methods = ik()->methods();
 184     int len = methods->length();
 185     int initialized = super_vtable_len;
 186 
 187     // Check each of this class's methods against super;
 188     // if override, replace in copy of super vtable, otherwise append to end
 189     for (int i = 0; i < len; i++) {
 190       // update_inherited_vtable can stop for gc - ensure using handles
 191       HandleMark hm(THREAD);
 192       assert(methods->at(i)->is_method(), "must be a Method*");
 193       methodHandle mh(THREAD, methods->at(i));
 194 
 195       bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
 196 
 197       if (needs_new_entry) {
 198         put_method_at(mh(), initialized);
 199         mh()->set_vtable_index(initialized); // set primary vtable index
 200         initialized++;
 201       }
 202     }
 203 
 204     // update vtable with default_methods
 205     Array<Method*>* default_methods = ik()->default_methods();
 206     if (default_methods != NULL) {
 207       len = default_methods->length();
 208       if (len > 0) {
 209         Array<int>* def_vtable_indices = NULL;
 210         if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
 211           def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
 212         } else {
 213           assert(def_vtable_indices->length() == len, "reinit vtable len?");
 214         }
 215         for (int i = 0; i < len; i++) {
 216           HandleMark hm(THREAD);
 217           assert(default_methods->at(i)->is_method(), "must be a Method*");
 218           methodHandle mh(THREAD, default_methods->at(i));
 219 
 220           bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
 221 
 222           // needs new entry
 223           if (needs_new_entry) {
 224             put_method_at(mh(), initialized);
 225             def_vtable_indices->at_put(i, initialized); //set vtable index
 226             initialized++;
 227           }
 228         }
 229       }
 230     }
 231 
 232     // add miranda methods; it will also return the updated initialized
 233     // Interfaces do not need interface methods in their vtables
 234     // This includes miranda methods and during later processing, default methods
 235     if (!ik()->is_interface()) {
 236       initialized = fill_in_mirandas(initialized);
 237     }
 238 
 239     // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
 240     // package_private -> public/protected), the vtable might actually be smaller than our initial
 241     // calculation.
 242     assert(initialized <= _length, "vtable initialization failed");
 243     for(;initialized < _length; initialized++) {
 244       put_method_at(NULL, initialized);
 245     }
 246     NOT_PRODUCT(verify(tty, true));
 247   }
 248 }
 249 
 250 // Called for cases where a method does not override its superclass' vtable entry
 251 // For bytecodes not produced by javac together it is possible that a method does not override
 252 // the superclass's method, but might indirectly override a super-super class's vtable entry
 253 // If none found, return a null superk, else return the superk of the method this does override
 254 // For public and protected methods: if they override a superclass, they will
 255 // also be overridden themselves appropriately.
 256 // Private methods do not override and are not overridden.
 257 // Package Private methods are trickier:
 258 // e.g. P1.A, pub m
 259 // P2.B extends A, package private m
 260 // P1.C extends B, public m
 261 // P1.C.m needs to override P1.A.m and can not override P2.B.m
 262 // Therefore: all package private methods need their own vtable entries for
 263 // them to be the root of an inheritance overriding decision
 264 // Package private methods may also override other vtable entries
 265 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
 266                             int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
 267   InstanceKlass* superk = initialsuper;
 268   while (superk != NULL && superk->super() != NULL) {
 269     InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
 270     klassVtable* ssVtable = supersuperklass->vtable();
 271     if (vtable_index < ssVtable->length()) {
 272       Method* super_method = ssVtable->method_at(vtable_index);
 273 #ifndef PRODUCT
 274       Symbol* name= target_method()->name();
 275       Symbol* signature = target_method()->signature();
 276       assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
 277 #endif
 278       if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
 279 #ifndef PRODUCT
 280         if (PrintVtables && Verbose) {
 281           ResourceMark rm(THREAD);
 282           char* sig = target_method()->name_and_sig_as_C_string();
 283           tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
 284            supersuperklass->internal_name(),
 285            _klass->internal_name(), sig, vtable_index);
 286            super_method->access_flags().print_on(tty);
 287            if (super_method->is_default_method()) {
 288              tty->print("default ");
 289            }
 290            tty->print("overriders flags: ");
 291            target_method->access_flags().print_on(tty);
 292            if (target_method->is_default_method()) {
 293              tty->print("default ");
 294            }
 295         }
 296 #endif /*PRODUCT*/
 297         break; // return found superk
 298       }
 299     } else  {
 300       // super class has no vtable entry here, stop transitive search
 301       superk = (InstanceKlass*)NULL;
 302       break;
 303     }
 304     // if no override found yet, continue to search up
 305     superk = InstanceKlass::cast(superk->super());
 306   }
 307 
 308   return superk;
 309 }
 310 
 311 // Update child's copy of super vtable for overrides
 312 // OR return true if a new vtable entry is required.
 313 // Only called for InstanceKlass's, i.e. not for arrays
 314 // If that changed, could not use _klass as handle for klass
 315 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method,
 316                                           int super_vtable_len, int default_index,
 317                                           bool checkconstraints, TRAPS) {
 318   ResourceMark rm;
 319   bool allocate_new = true;
 320   assert(klass->oop_is_instance(), "must be InstanceKlass");
 321 
 322   Array<int>* def_vtable_indices = NULL;
 323   bool is_default = false;
 324   // default methods are concrete methods in superinterfaces which are added to the vtable
 325   // with their real method_holder
 326   // Since vtable and itable indices share the same storage, don't touch
 327   // the default method's real vtable/itable index
 328   // default_vtable_indices stores the vtable value relative to this inheritor
 329   if (default_index >= 0 ) {
 330     is_default = true;
 331     def_vtable_indices = klass->default_vtable_indices();
 332     assert(def_vtable_indices != NULL, "def vtable alloc?");
 333     assert(default_index <= def_vtable_indices->length(), "def vtable len?");
 334   } else {
 335     assert(klass == target_method()->method_holder(), "caller resp.");
 336     // Initialize the method's vtable index to "nonvirtual".
 337     // If we allocate a vtable entry, we will update it to a non-negative number.
 338     target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
 339   }
 340 
 341   // Static and <init> methods are never in
 342   if (target_method()->is_static() || target_method()->name() ==  vmSymbols::object_initializer_name()) {
 343     return false;
 344   }
 345 
 346   if (target_method->is_final_method(klass->access_flags())) {
 347     // a final method never needs a new entry; final methods can be statically
 348     // resolved and they have to be present in the vtable only if they override
 349     // a super's method, in which case they re-use its entry
 350     allocate_new = false;
 351   } else if (klass->is_interface()) {
 352     allocate_new = false;  // see note below in needs_new_vtable_entry
 353     // An interface never allocates new vtable slots, only inherits old ones.
 354     // This method will either be assigned its own itable index later,
 355     // or be assigned an inherited vtable index in the loop below.
 356     // default methods inherited by classes store their vtable indices
 357     // in the inheritor's default_vtable_indices
 358     // default methods inherited by interfaces may already have a
 359     // valid itable index, if so, don't change it
 360     // overpass methods in an interface will be assigned an itable index later
 361     // by an inheriting class
 362     if (!is_default || !target_method()->has_itable_index()) {
 363       target_method()->set_vtable_index(Method::pending_itable_index);
 364     }
 365   }
 366 
 367   // we need a new entry if there is no superclass
 368   if (klass->super() == NULL) {
 369     return allocate_new;
 370   }
 371 
 372   // private methods in classes always have a new entry in the vtable
 373   // specification interpretation since classic has
 374   // private methods not overriding
 375   // JDK8 adds private methods in interfaces which require invokespecial
 376   if (target_method()->is_private()) {
 377     return allocate_new;
 378   }
 379 
 380   // search through the vtable and update overridden entries
 381   // Since check_signature_loaders acquires SystemDictionary_lock
 382   // which can block for gc, once we are in this loop, use handles
 383   // For classfiles built with >= jdk7, we now look for transitive overrides
 384 
 385   Symbol* name = target_method()->name();
 386   Symbol* signature = target_method()->signature();
 387 
 388   KlassHandle target_klass(THREAD, target_method()->method_holder());
 389   if (target_klass == NULL) {
 390     target_klass = _klass;
 391   }
 392 
 393   Handle target_loader(THREAD, target_klass->class_loader());
 394 
 395   Symbol* target_classname = target_klass->name();
 396   for(int i = 0; i < super_vtable_len; i++) {
 397     Method* super_method = method_at(i);
 398     // Check if method name matches
 399     if (super_method->name() == name && super_method->signature() == signature) {
 400 
 401       // get super_klass for method_holder for the found method
 402       InstanceKlass* super_klass =  super_method->method_holder();
 403 
 404       if (is_default
 405           || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
 406           || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
 407           && ((super_klass = find_transitive_override(super_klass,
 408                              target_method, i, target_loader,
 409                              target_classname, THREAD))
 410                              != (InstanceKlass*)NULL))))
 411         {
 412         // Package private methods always need a new entry to root their own
 413         // overriding. They may also override other methods.
 414         if (!target_method()->is_package_private()) {
 415           allocate_new = false;
 416         }
 417 
 418         if (checkconstraints) {
 419         // Override vtable entry if passes loader constraint check
 420         // if loader constraint checking requested
 421         // No need to visit his super, since he and his super
 422         // have already made any needed loader constraints.
 423         // Since loader constraints are transitive, it is enough
 424         // to link to the first super, and we get all the others.
 425           Handle super_loader(THREAD, super_klass->class_loader());
 426 
 427           if (target_loader() != super_loader()) {
 428             ResourceMark rm(THREAD);
 429             Symbol* failed_type_symbol =
 430               SystemDictionary::check_signature_loaders(signature, target_loader,
 431                                                         super_loader, true,
 432                                                         CHECK_(false));
 433             if (failed_type_symbol != NULL) {
 434               const char* msg = "loader constraint violation: when resolving "
 435                 "overridden method \"%s\" the class loader (instance"
 436                 " of %s) of the current class, %s, and its superclass loader "
 437                 "(instance of %s), have different Class objects for the type "
 438                 "%s used in the signature";
 439               char* sig = target_method()->name_and_sig_as_C_string();
 440               const char* loader1 = SystemDictionary::loader_name(target_loader());
 441               char* current = target_klass->name()->as_C_string();
 442               const char* loader2 = SystemDictionary::loader_name(super_loader());
 443               char* failed_type_name = failed_type_symbol->as_C_string();
 444               size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
 445                 strlen(current) + strlen(loader2) + strlen(failed_type_name);
 446               char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
 447               jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
 448                            failed_type_name);
 449               THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
 450             }
 451           }
 452        }
 453 
 454        put_method_at(target_method(), i);
 455        if (!is_default) {
 456          target_method()->set_vtable_index(i);
 457        } else {
 458          if (def_vtable_indices != NULL) {
 459            def_vtable_indices->at_put(default_index, i);
 460          }
 461          assert(super_method->is_default_method() || super_method->is_overpass()
 462                 || super_method->is_abstract(), "default override error");
 463        }
 464 
 465 
 466 #ifndef PRODUCT
 467         if (PrintVtables && Verbose) {
 468           ResourceMark rm(THREAD);
 469           char* sig = target_method()->name_and_sig_as_C_string();
 470           tty->print("overriding with %s::%s index %d, original flags: ",
 471            target_klass->internal_name(), sig, i);
 472            super_method->access_flags().print_on(tty);
 473            if (super_method->is_default_method()) {
 474              tty->print("default ");
 475            }
 476            if (super_method->is_overpass()) {
 477              tty->print("overpass");
 478            }
 479            tty->print("overriders flags: ");
 480            target_method->access_flags().print_on(tty);
 481            if (target_method->is_default_method()) {
 482              tty->print("default ");
 483            }
 484            if (target_method->is_overpass()) {
 485              tty->print("overpass");
 486            }
 487            tty->cr();
 488         }
 489 #endif /*PRODUCT*/
 490       } else {
 491         // allocate_new = true; default. We might override one entry,
 492         // but not override another. Once we override one, not need new
 493 #ifndef PRODUCT
 494         if (PrintVtables && Verbose) {
 495           ResourceMark rm(THREAD);
 496           char* sig = target_method()->name_and_sig_as_C_string();
 497           tty->print("NOT overriding with %s::%s index %d, original flags: ",
 498            target_klass->internal_name(), sig,i);
 499            super_method->access_flags().print_on(tty);
 500            if (super_method->is_default_method()) {
 501              tty->print("default ");
 502            }
 503            if (super_method->is_overpass()) {
 504              tty->print("overpass");
 505            }
 506            tty->print("overriders flags: ");
 507            target_method->access_flags().print_on(tty);
 508            if (target_method->is_default_method()) {
 509              tty->print("default ");
 510            }
 511            if (target_method->is_overpass()) {
 512              tty->print("overpass");
 513            }
 514            tty->cr();
 515         }
 516 #endif /*PRODUCT*/
 517       }
 518     }
 519   }
 520   return allocate_new;
 521 }
 522 
 523 void klassVtable::put_method_at(Method* m, int index) {
 524 #ifndef PRODUCT
 525   if (PrintVtables && Verbose) {
 526     ResourceMark rm;
 527     const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
 528     tty->print("adding %s at index %d, flags: ", sig, index);
 529     if (m != NULL) {
 530       m->access_flags().print_on(tty);
 531       if (m->is_default_method()) {
 532         tty->print("default ");
 533       }
 534       if (m->is_overpass()) {
 535         tty->print("overpass");
 536       }
 537     }
 538     tty->cr();
 539   }
 540 #endif
 541   table()[index].set(m);
 542 }
 543 
 544 // Find out if a method "m" with superclass "super", loader "classloader" and
 545 // name "classname" needs a new vtable entry.  Let P be a class package defined
 546 // by "classloader" and "classname".
 547 // NOTE: The logic used here is very similar to the one used for computing
 548 // the vtables indices for a method. We cannot directly use that function because,
 549 // we allocate the InstanceKlass at load time, and that requires that the
 550 // superclass has been loaded.
 551 // However, the vtable entries are filled in at link time, and therefore
 552 // the superclass' vtable may not yet have been filled in.
 553 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
 554                                          Klass* super,
 555                                          Handle classloader,
 556                                          Symbol* classname,
 557                                          AccessFlags class_flags,
 558                                          TRAPS) {
 559   if (class_flags.is_interface()) {
 560     // Interfaces do not use vtables, except for java.lang.Object methods,
 561     // so there is no point to assigning
 562     // a vtable index to any of their local methods.  If we refrain from doing this,
 563     // we can use Method::_vtable_index to hold the itable index
 564     return false;
 565   }
 566 
 567   if (target_method->is_final_method(class_flags) ||
 568       // a final method never needs a new entry; final methods can be statically
 569       // resolved and they have to be present in the vtable only if they override
 570       // a super's method, in which case they re-use its entry
 571       (target_method()->is_static()) ||
 572       // static methods don't need to be in vtable
 573       (target_method()->name() ==  vmSymbols::object_initializer_name())
 574       // <init> is never called dynamically-bound
 575       ) {
 576     return false;
 577   }
 578 
 579   // Concrete interface methods do not need new entries, they override
 580   // abstract method entries using default inheritance rules
 581   if (target_method()->method_holder() != NULL &&
 582       target_method()->method_holder()->is_interface()  &&
 583       !target_method()->is_abstract() ) {
 584     return false;
 585   }
 586 
 587   // we need a new entry if there is no superclass
 588   if (super == NULL) {
 589     return true;
 590   }
 591 
 592   // private methods in classes always have a new entry in the vtable
 593   // specification interpretation since classic has
 594   // private methods not overriding
 595   // JDK8 adds private  methods in interfaces which require invokespecial
 596   if (target_method()->is_private()) {
 597     return true;
 598   }
 599 
 600   // Package private methods always need a new entry to root their own
 601   // overriding. This allows transitive overriding to work.
 602   if (target_method()->is_package_private()) {
 603     return true;
 604   }
 605 
 606   // search through the super class hierarchy to see if we need
 607   // a new entry
 608   ResourceMark rm;
 609   Symbol* name = target_method()->name();
 610   Symbol* signature = target_method()->signature();
 611   Klass* k = super;
 612   Method* super_method = NULL;
 613   InstanceKlass *holder = NULL;
 614   Method* recheck_method =  NULL;
 615   while (k != NULL) {
 616     // lookup through the hierarchy for a method with matching name and sign.
 617     super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
 618     if (super_method == NULL) {
 619       break; // we still have to search for a matching miranda method
 620     }
 621     // get the class holding the matching method
 622     // make sure you use that class for is_override
 623     InstanceKlass* superk = super_method->method_holder();
 624     // we want only instance method matches
 625     // pretend private methods are not in the super vtable
 626     // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
 627     // ignore private, c.m pub does override a.m pub
 628     // For classes that were not javac'd together, we also do transitive overriding around
 629     // methods that have less accessibility
 630     if ((!super_method->is_static()) &&
 631        (!super_method->is_private())) {
 632       if (superk->is_override(super_method, classloader, classname, THREAD)) {
 633         return false;
 634       // else keep looking for transitive overrides
 635       }
 636     }
 637 
 638     // Start with lookup result and continue to search up
 639     k = superk->super(); // haven't found an override match yet; continue to look
 640   }
 641 
 642   // if the target method is public or protected it may have a matching
 643   // miranda method in the super, whose entry it should re-use.
 644   // Actually, to handle cases that javac would not generate, we need
 645   // this check for all access permissions.
 646   InstanceKlass *sk = InstanceKlass::cast(super);
 647   if (sk->has_miranda_methods()) {
 648     if (sk->lookup_method_in_all_interfaces(name, signature, Klass::normal) != NULL) {
 649       return false;  // found a matching miranda; we do not need a new entry
 650     }
 651   }
 652   return true; // found no match; we need a new entry
 653 }
 654 
 655 // Support for miranda methods
 656 
 657 // get the vtable index of a miranda method with matching "name" and "signature"
 658 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
 659   // search from the bottom, might be faster
 660   for (int i = (length() - 1); i >= 0; i--) {
 661     Method* m = table()[i].method();
 662     if (is_miranda_entry_at(i) &&
 663         m->name() == name && m->signature() == signature) {
 664       return i;
 665     }
 666   }
 667   return Method::invalid_vtable_index;
 668 }
 669 
 670 // check if an entry at an index is miranda
 671 // requires that method m at entry be declared ("held") by an interface.
 672 bool klassVtable::is_miranda_entry_at(int i) {
 673   Method* m = method_at(i);
 674   Klass* method_holder = m->method_holder();
 675   InstanceKlass *mhk = InstanceKlass::cast(method_holder);
 676 
 677   // miranda methods are public abstract instance interface methods in a class's vtable
 678   if (mhk->is_interface()) {
 679     assert(m->is_public(), "should be public");
 680     assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
 681     // the search could find a miranda or a default method
 682     if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
 683       return true;
 684     }
 685   }
 686   return false;
 687 }
 688 
 689 // check if a method is a miranda method, given a class's methods table,
 690 // its default_method table  and its super
 691 // Miranda methods are calculated twice:
 692 // first: before vtable size calculation: including abstract and default
 693 // This is seen by default method creation
 694 // Second: recalculated during vtable initialization: only abstract
 695 // This is seen by link resolution and selection.
 696 // "miranda" means not static, not defined by this class.
 697 // private methods in interfaces do not belong in the miranda list.
 698 // the caller must make sure that the method belongs to an interface implemented by the class
 699 // Miranda methods only include public interface instance methods
 700 // Not private methods, not static methods, not default == concrete abstract
 701 // Miranda methods also do not include overpass methods in interfaces
 702 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
 703                              Array<Method*>* default_methods, Klass* super) {
 704   if (m->is_static() || m->is_private() || m->is_overpass()) {
 705     return false;
 706   }
 707   Symbol* name = m->name();
 708   Symbol* signature = m->signature();
 709 
 710   if (InstanceKlass::find_instance_method(class_methods, name, signature) == NULL) {
 711     // did not find it in the method table of the current class
 712     if ((default_methods == NULL) ||
 713         InstanceKlass::find_method(default_methods, name, signature) == NULL) {
 714       if (super == NULL) {
 715         // super doesn't exist
 716         return true;
 717       }
 718 
 719       Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature);
 720       while (mo != NULL && mo->access_flags().is_static()
 721              && mo->method_holder() != NULL
 722              && mo->method_holder()->super() != NULL)
 723       {
 724          mo = mo->method_holder()->super()->uncached_lookup_method(name, signature, Klass::normal);
 725       }
 726       if (mo == NULL || mo->access_flags().is_private() ) {
 727         // super class hierarchy does not implement it or protection is different
 728         return true;
 729       }
 730     }
 731   }
 732 
 733   return false;
 734 }
 735 
 736 // Scans current_interface_methods for miranda methods that do not
 737 // already appear in new_mirandas, or default methods,  and are also not defined-and-non-private
 738 // in super (superclass).  These mirandas are added to all_mirandas if it is
 739 // not null; in addition, those that are not duplicates of miranda methods
 740 // inherited by super from its interfaces are added to new_mirandas.
 741 // Thus, new_mirandas will be the set of mirandas that this class introduces,
 742 // all_mirandas will be the set of all mirandas applicable to this class
 743 // including all defined in superclasses.
 744 void klassVtable::add_new_mirandas_to_lists(
 745     GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
 746     Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
 747     Array<Method*>* default_methods, Klass* super) {
 748 
 749   // iterate thru the current interface's method to see if it a miranda
 750   int num_methods = current_interface_methods->length();
 751   for (int i = 0; i < num_methods; i++) {
 752     Method* im = current_interface_methods->at(i);
 753     bool is_duplicate = false;
 754     int num_of_current_mirandas = new_mirandas->length();
 755     // check for duplicate mirandas in different interfaces we implement
 756     for (int j = 0; j < num_of_current_mirandas; j++) {
 757       Method* miranda = new_mirandas->at(j);
 758       if ((im->name() == miranda->name()) &&
 759           (im->signature() == miranda->signature())) {
 760         is_duplicate = true;
 761         break;
 762       }
 763     }
 764 
 765     if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
 766       if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all?
 767         InstanceKlass *sk = InstanceKlass::cast(super);
 768         // check if it is a duplicate of a super's miranda
 769         if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::normal) == NULL) {
 770           new_mirandas->append(im);
 771         }
 772         if (all_mirandas != NULL) {
 773           all_mirandas->append(im);
 774         }
 775       }
 776     }
 777   }
 778 }
 779 
 780 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
 781                                GrowableArray<Method*>* all_mirandas,
 782                                Klass* super, Array<Method*>* class_methods,
 783                                Array<Method*>* default_methods,
 784                                Array<Klass*>* local_interfaces) {
 785   assert((new_mirandas->length() == 0) , "current mirandas must be 0");
 786 
 787   // iterate thru the local interfaces looking for a miranda
 788   int num_local_ifs = local_interfaces->length();
 789   for (int i = 0; i < num_local_ifs; i++) {
 790     InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
 791     add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 792                               ik->methods(), class_methods,
 793                               default_methods, super);
 794     // iterate thru each local's super interfaces
 795     Array<Klass*>* super_ifs = ik->transitive_interfaces();
 796     int num_super_ifs = super_ifs->length();
 797     for (int j = 0; j < num_super_ifs; j++) {
 798       InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
 799       add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 800                                 sik->methods(), class_methods,
 801                                 default_methods, super);
 802     }
 803   }
 804 }
 805 
 806 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
 807 // and append them into the vtable starting at index initialized,
 808 // return the new value of initialized.
 809 // Miranda methods use vtable entries, but do not get assigned a vtable_index
 810 // The vtable_index is discovered by searching from the end of the vtable
 811 int klassVtable::fill_in_mirandas(int initialized) {
 812   GrowableArray<Method*> mirandas(20);
 813   get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
 814                ik()->default_methods(), ik()->local_interfaces());
 815   for (int i = 0; i < mirandas.length(); i++) {
 816     if (PrintVtables && Verbose) {
 817       Method* meth = mirandas.at(i);
 818       ResourceMark rm(Thread::current());
 819       if (meth != NULL) {
 820         char* sig = meth->name_and_sig_as_C_string();
 821         tty->print("fill in mirandas with %s index %d, flags: ",
 822           sig, initialized);
 823         meth->access_flags().print_on(tty);
 824         if (meth->is_default_method()) {
 825           tty->print("default ");
 826         }
 827         tty->cr();
 828       }
 829     }
 830     put_method_at(mirandas.at(i), initialized);
 831     ++initialized;
 832   }
 833   return initialized;
 834 }
 835 
 836 // Copy this class's vtable to the vtable beginning at start.
 837 // Used to copy superclass vtable to prefix of subclass's vtable.
 838 void klassVtable::copy_vtable_to(vtableEntry* start) {
 839   Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
 840 }
 841 
 842 #if INCLUDE_JVMTI
 843 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
 844   // If old_method is default, find this vtable index in default_vtable_indices
 845   // and replace that method in the _default_methods list
 846   bool updated = false;
 847 
 848   Array<Method*>* default_methods = ik()->default_methods();
 849   if (default_methods != NULL) {
 850     int len = default_methods->length();
 851     for (int idx = 0; idx < len; idx++) {
 852       if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
 853         if (default_methods->at(idx) == old_method) {
 854           default_methods->at_put(idx, new_method);
 855           updated = true;
 856         }
 857         break;
 858       }
 859     }
 860   }
 861   return updated;
 862 }
 863 void klassVtable::adjust_method_entries(Method** old_methods, Method** new_methods,
 864                                         int methods_length, bool * trace_name_printed) {
 865   // search the vtable for uses of either obsolete or EMCP methods
 866   for (int j = 0; j < methods_length; j++) {
 867     Method* old_method = old_methods[j];
 868     Method* new_method = new_methods[j];
 869 
 870     // In the vast majority of cases we could get the vtable index
 871     // by using:  old_method->vtable_index()
 872     // However, there are rare cases, eg. sun.awt.X11.XDecoratedPeer.getX()
 873     // in sun.awt.X11.XFramePeer where methods occur more than once in the
 874     // vtable, so, alas, we must do an exhaustive search.
 875     for (int index = 0; index < length(); index++) {
 876       if (unchecked_method_at(index) == old_method) {
 877         put_method_at(new_method, index);
 878           // For default methods, need to update the _default_methods array
 879           // which can only have one method entry for a given signature
 880           bool updated_default = false;
 881           if (old_method->is_default_method()) {
 882             updated_default = adjust_default_method(index, old_method, new_method);
 883           }
 884 
 885         if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
 886           if (!(*trace_name_printed)) {
 887             // RC_TRACE_MESG macro has an embedded ResourceMark
 888             RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s",
 889                            klass()->external_name(),
 890                            old_method->method_holder()->external_name()));
 891             *trace_name_printed = true;
 892           }
 893           // RC_TRACE macro has an embedded ResourceMark
 894           RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s",
 895                                 new_method->name()->as_C_string(),
 896                                 new_method->signature()->as_C_string(),
 897                                 updated_default ? "true" : "false"));
 898         }
 899         // cannot 'break' here; see for-loop comment above.
 900       }
 901     }
 902   }
 903 }
 904 
 905 // a vtable should never contain old or obsolete methods
 906 bool klassVtable::check_no_old_or_obsolete_entries() {
 907   for (int i = 0; i < length(); i++) {
 908     Method* m = unchecked_method_at(i);
 909     if (m != NULL &&
 910         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
 911       return false;
 912     }
 913   }
 914   return true;
 915 }
 916 
 917 void klassVtable::dump_vtable() {
 918   tty->print_cr("vtable dump --");
 919   for (int i = 0; i < length(); i++) {
 920     Method* m = unchecked_method_at(i);
 921     if (m != NULL) {
 922       tty->print("      (%5d)  ", i);
 923       m->access_flags().print_on(tty);
 924       if (m->is_default_method()) {
 925         tty->print("default ");
 926       }
 927       if (m->is_overpass()) {
 928         tty->print("overpass");
 929       }
 930       tty->print(" --  ");
 931       m->print_name(tty);
 932       tty->cr();
 933     }
 934   }
 935 }
 936 #endif // INCLUDE_JVMTI
 937 
 938 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
 939 void klassVtable::clear_vtable() {
 940   for (int i = 0; i < _length; i++) table()[i].clear();
 941 }
 942 
 943 bool klassVtable::is_initialized() {
 944   return _length == 0 || table()[0].method() != NULL;
 945 }
 946 
 947 //-----------------------------------------------------------------------------------------
 948 // Itable code
 949 
 950 // Initialize a itableMethodEntry
 951 void itableMethodEntry::initialize(Method* m) {
 952   if (m == NULL) return;
 953 
 954   _method = m;
 955 }
 956 
 957 klassItable::klassItable(instanceKlassHandle klass) {
 958   _klass = klass;
 959 
 960   if (klass->itable_length() > 0) {
 961     itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
 962     if (offset_entry  != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
 963       // First offset entry points to the first method_entry
 964       intptr_t* method_entry  = (intptr_t *)(((address)klass()) + offset_entry->offset());
 965       intptr_t* end         = klass->end_of_itable();
 966 
 967       _table_offset      = (intptr_t*)offset_entry - (intptr_t*)klass();
 968       _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
 969       _size_method_table = (end - method_entry)                  / itableMethodEntry::size();
 970       assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
 971       return;
 972     }
 973   }
 974 
 975   // The length of the itable was either zero, or it has not yet been initialized.
 976   _table_offset      = 0;
 977   _size_offset_table = 0;
 978   _size_method_table = 0;
 979 }
 980 
 981 static int initialize_count = 0;
 982 
 983 // Initialization
 984 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
 985   if (_klass->is_interface()) {
 986     // This needs to go after vtable indices are assigned but
 987     // before implementors need to know the number of itable indices.
 988     assign_itable_indices_for_interface(_klass());
 989   }
 990 
 991   // Cannot be setup doing bootstrapping, interfaces don't have
 992   // itables, and klass with only ones entry have empty itables
 993   if (Universe::is_bootstrapping() ||
 994       _klass->is_interface() ||
 995       _klass->itable_length() == itableOffsetEntry::size()) return;
 996 
 997   // There's alway an extra itable entry so we can null-terminate it.
 998   guarantee(size_offset_table() >= 1, "too small");
 999   int num_interfaces = size_offset_table() - 1;
1000   if (num_interfaces > 0) {
1001     if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count,
1002                                     _klass->name()->as_C_string());
1003 
1004 
1005     // Iterate through all interfaces
1006     int i;
1007     for(i = 0; i < num_interfaces; i++) {
1008       itableOffsetEntry* ioe = offset_entry(i);
1009       HandleMark hm(THREAD);
1010       KlassHandle interf_h (THREAD, ioe->interface_klass());
1011       assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
1012       initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
1013     }
1014 
1015   }
1016   // Check that the last entry is empty
1017   itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1018   guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1019 }
1020 
1021 
1022 inline bool interface_method_needs_itable_index(Method* m) {
1023   if (m->is_static())           return false;   // e.g., Stream.empty
1024   if (m->is_initializer())      return false;   // <init> or <clinit>
1025   // If an interface redeclares a method from java.lang.Object,
1026   // it should already have a vtable index, don't touch it.
1027   // e.g., CharSequence.toString (from initialize_vtable)
1028   // if (m->has_vtable_index())  return false; // NO!
1029   return true;
1030 }
1031 
1032 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1033   // an interface does not have an itable, but its methods need to be numbered
1034   if (TraceItables) tty->print_cr("%3d: Initializing itable for interface %s", ++initialize_count,
1035                                   klass->name()->as_C_string());
1036   Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1037   int nof_methods = methods->length();
1038   int ime_num = 0;
1039   for (int i = 0; i < nof_methods; i++) {
1040     Method* m = methods->at(i);
1041     if (interface_method_needs_itable_index(m)) {
1042       assert(!m->is_final_method(), "no final interface methods");
1043       // If m is already assigned a vtable index, do not disturb it.
1044       if (TraceItables && Verbose) {
1045         ResourceMark rm;
1046         const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
1047         if (m->has_vtable_index()) {
1048           tty->print("itable index %d for method: %s, flags: ", m->vtable_index(), sig);
1049         } else {
1050           tty->print("itable index %d for method: %s, flags: ", ime_num, sig);
1051         }
1052         if (m != NULL) {
1053           m->access_flags().print_on(tty);
1054           if (m->is_default_method()) {
1055             tty->print("default ");
1056           }
1057           if (m->is_overpass()) {
1058             tty->print("overpass");
1059           }
1060         }
1061         tty->cr();
1062       }
1063       if (!m->has_vtable_index()) {
1064         assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable");
1065         m->set_itable_index(ime_num);
1066         // Progress to next itable entry
1067         ime_num++;
1068       }
1069     }
1070   }
1071   assert(ime_num == method_count_for_interface(klass), "proper sizing");
1072   return ime_num;
1073 }
1074 
1075 int klassItable::method_count_for_interface(Klass* interf) {
1076   assert(interf->oop_is_instance(), "must be");
1077   assert(interf->is_interface(), "must be");
1078   Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1079   int nof_methods = methods->length();
1080   while (nof_methods > 0) {
1081     Method* m = methods->at(nof_methods-1);
1082     if (m->has_itable_index()) {
1083       int length = m->itable_index() + 1;
1084 #ifdef ASSERT
1085       while (nof_methods = 0) {
1086         m = methods->at(--nof_methods);
1087         assert(!m->has_itable_index() || m->itable_index() < length, "");
1088       }
1089 #endif //ASSERT
1090       return length;  // return the rightmost itable index, plus one
1091     }
1092     nof_methods -= 1;
1093   }
1094   // no methods have itable indices
1095   return 0;
1096 }
1097 
1098 
1099 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
1100   Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();
1101   int nof_methods = methods->length();
1102   HandleMark hm;
1103   assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
1104   Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader());
1105 
1106   int ime_count = method_count_for_interface(interf_h());
1107   for (int i = 0; i < nof_methods; i++) {
1108     Method* m = methods->at(i);
1109     methodHandle target;
1110     if (m->has_itable_index()) {
1111       // This search must match the runtime resolution, i.e. selection search for invokeinterface
1112       // to correctly enforce loader constraints for interface method inheritance
1113       LinkResolver::lookup_instance_method_in_klasses(target, _klass, m->name(), m->signature(), CHECK);
1114     }
1115     if (target == NULL || !target->is_public() || target->is_abstract()) {
1116       // Entry does not resolve. Leave it empty for AbstractMethodError.
1117         if (!(target == NULL) && !target->is_public()) {
1118           // Stuff an IllegalAccessError throwing method in there instead.
1119           itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()].
1120               initialize(Universe::throw_illegal_access_error());
1121         }
1122     } else {
1123       // Entry did resolve, check loader constraints before initializing
1124       // if checkconstraints requested
1125       if (checkconstraints) {
1126         Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1127         if (method_holder_loader() != interface_loader()) {
1128           ResourceMark rm(THREAD);
1129           Symbol* failed_type_symbol =
1130             SystemDictionary::check_signature_loaders(m->signature(),
1131                                                       method_holder_loader,
1132                                                       interface_loader,
1133                                                       true, CHECK);
1134           if (failed_type_symbol != NULL) {
1135             const char* msg = "loader constraint violation in interface "
1136               "itable initialization: when resolving method \"%s\" the class"
1137               " loader (instance of %s) of the current class, %s, "
1138               "and the class loader (instance of %s) for interface "
1139               "%s have different Class objects for the type %s "
1140               "used in the signature";
1141             char* sig = target()->name_and_sig_as_C_string();
1142             const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
1143             char* current = _klass->name()->as_C_string();
1144             const char* loader2 = SystemDictionary::loader_name(interface_loader());
1145             char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string();
1146             char* failed_type_name = failed_type_symbol->as_C_string();
1147             size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
1148               strlen(current) + strlen(loader2) + strlen(iface) +
1149               strlen(failed_type_name);
1150             char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1151             jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
1152                          iface, failed_type_name);
1153             THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1154           }
1155         }
1156       }
1157 
1158       // ime may have moved during GC so recalculate address
1159       int ime_num = m->itable_index();
1160       assert(ime_num < ime_count, "oob");
1161       itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target());
1162       if (TraceItables && Verbose) {
1163         ResourceMark rm(THREAD);
1164         if (target() != NULL) {
1165           char* sig = target()->name_and_sig_as_C_string();
1166           tty->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1167                     interf_h()->internal_name(), ime_num, sig,
1168                     target()->method_holder()->internal_name());
1169           tty->print("target_method flags: ");
1170           target()->access_flags().print_on(tty);
1171           if (target()->is_default_method()) {
1172             tty->print("default ");
1173           }
1174           tty->cr();
1175         }
1176       }
1177     }
1178   }
1179 }
1180 
1181 // Update entry for specific Method*
1182 void klassItable::initialize_with_method(Method* m) {
1183   itableMethodEntry* ime = method_entry(0);
1184   for(int i = 0; i < _size_method_table; i++) {
1185     if (ime->method() == m) {
1186       ime->initialize(m);
1187     }
1188     ime++;
1189   }
1190 }
1191 
1192 #if INCLUDE_JVMTI
1193 void klassItable::adjust_method_entries(Method** old_methods, Method** new_methods,
1194                                         int methods_length, bool * trace_name_printed) {
1195   // search the itable for uses of either obsolete or EMCP methods
1196   for (int j = 0; j < methods_length; j++) {
1197     Method* old_method = old_methods[j];
1198     Method* new_method = new_methods[j];
1199     itableMethodEntry* ime = method_entry(0);
1200 
1201     // The itable can describe more than one interface and the same
1202     // method signature can be specified by more than one interface.
1203     // This means we have to do an exhaustive search to find all the
1204     // old_method references.
1205     for (int i = 0; i < _size_method_table; i++) {
1206       if (ime->method() == old_method) {
1207         ime->initialize(new_method);
1208 
1209         if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
1210           if (!(*trace_name_printed)) {
1211             // RC_TRACE_MESG macro has an embedded ResourceMark
1212             RC_TRACE_MESG(("adjust: name=%s",
1213               old_method->method_holder()->external_name()));
1214             *trace_name_printed = true;
1215           }
1216           // RC_TRACE macro has an embedded ResourceMark
1217           RC_TRACE(0x00200000, ("itable method update: %s(%s)",
1218             new_method->name()->as_C_string(),
1219             new_method->signature()->as_C_string()));
1220         }
1221         // cannot 'break' here; see for-loop comment above.
1222       }
1223       ime++;
1224     }
1225   }
1226 }
1227 
1228 // an itable should never contain old or obsolete methods
1229 bool klassItable::check_no_old_or_obsolete_entries() {
1230   itableMethodEntry* ime = method_entry(0);
1231   for (int i = 0; i < _size_method_table; i++) {
1232     Method* m = ime->method();
1233     if (m != NULL &&
1234         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1235       if (m->method_holder() != SystemDictionary::misc_Unsafe_klass() ||
1236           m->name() != vmSymbols::throwIllegalAccessError_name()) {
1237         return false;
1238       }
1239       // replace the old Unsafe.throwIllegalAccessError() method
1240       // with the latest version
1241       ime->initialize(Universe::throw_illegal_access_error());
1242     }
1243     ime++;
1244   }
1245   return true;
1246 }
1247 
1248 void klassItable::dump_itable() {
1249   itableMethodEntry* ime = method_entry(0);
1250   tty->print_cr("itable dump --");
1251   for (int i = 0; i < _size_method_table; i++) {
1252     Method* m = ime->method();
1253     if (m != NULL) {
1254       tty->print("      (%5d)  ", i);
1255       m->access_flags().print_on(tty);
1256       if (m->is_default_method()) {
1257         tty->print("default ");
1258       }
1259       tty->print(" --  ");
1260       m->print_name(tty);
1261       tty->cr();
1262     }
1263     ime++;
1264   }
1265 }
1266 #endif // INCLUDE_JVMTI
1267 
1268 
1269 // Setup
1270 class InterfaceVisiterClosure : public StackObj {
1271  public:
1272   virtual void doit(Klass* intf, int method_count) = 0;
1273 };
1274 
1275 // Visit all interfaces with at least one itable method
1276 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1277   // Handle array argument
1278   for(int i = 0; i < transitive_intf->length(); i++) {
1279     Klass* intf = transitive_intf->at(i);
1280     assert(intf->is_interface(), "sanity check");
1281 
1282     // Find no. of itable methods
1283     int method_count = 0;
1284     // method_count = klassItable::method_count_for_interface(intf);
1285     Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1286     if (methods->length() > 0) {
1287       for (int i = methods->length(); --i >= 0; ) {
1288         if (interface_method_needs_itable_index(methods->at(i))) {
1289           method_count++;
1290         }
1291       }
1292     }
1293 
1294     // Only count interfaces with at least one method
1295     if (method_count > 0) {
1296       blk->doit(intf, method_count);
1297     }
1298   }
1299 }
1300 
1301 class CountInterfacesClosure : public InterfaceVisiterClosure {
1302  private:
1303   int _nof_methods;
1304   int _nof_interfaces;
1305  public:
1306    CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1307 
1308    int nof_methods() const    { return _nof_methods; }
1309    int nof_interfaces() const { return _nof_interfaces; }
1310 
1311    void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1312 };
1313 
1314 class SetupItableClosure : public InterfaceVisiterClosure  {
1315  private:
1316   itableOffsetEntry* _offset_entry;
1317   itableMethodEntry* _method_entry;
1318   address            _klass_begin;
1319  public:
1320   SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1321     _klass_begin  = klass_begin;
1322     _offset_entry = offset_entry;
1323     _method_entry = method_entry;
1324   }
1325 
1326   itableMethodEntry* method_entry() const { return _method_entry; }
1327 
1328   void doit(Klass* intf, int method_count) {
1329     int offset = ((address)_method_entry) - _klass_begin;
1330     _offset_entry->initialize(intf, offset);
1331     _offset_entry++;
1332     _method_entry += method_count;
1333   }
1334 };
1335 
1336 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1337   // Count no of interfaces and total number of interface methods
1338   CountInterfacesClosure cic;
1339   visit_all_interfaces(transitive_interfaces, &cic);
1340 
1341   // There's alway an extra itable entry so we can null-terminate it.
1342   int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1343 
1344   // Statistics
1345   update_stats(itable_size * HeapWordSize);
1346 
1347   return itable_size;
1348 }
1349 
1350 
1351 // Fill out offset table and interface klasses into the itable space
1352 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
1353   if (klass->itable_length() == 0) return;
1354   assert(!klass->is_interface(), "Should have zero length itable");
1355 
1356   // Count no of interfaces and total number of interface methods
1357   CountInterfacesClosure cic;
1358   visit_all_interfaces(klass->transitive_interfaces(), &cic);
1359   int nof_methods    = cic.nof_methods();
1360   int nof_interfaces = cic.nof_interfaces();
1361 
1362   // Add one extra entry so we can null-terminate the table
1363   nof_interfaces++;
1364 
1365   assert(compute_itable_size(klass->transitive_interfaces()) ==
1366          calc_itable_size(nof_interfaces, nof_methods),
1367          "mismatch calculation of itable size");
1368 
1369   // Fill-out offset table
1370   itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1371   itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1372   intptr_t* end               = klass->end_of_itable();
1373   assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1374   assert((oop*)(end) == (oop*)(ime + nof_methods),                      "wrong offset calculation (2)");
1375 
1376   // Visit all interfaces and initialize itable offset table
1377   SetupItableClosure sic((address)klass(), ioe, ime);
1378   visit_all_interfaces(klass->transitive_interfaces(), &sic);
1379 
1380 #ifdef ASSERT
1381   ime  = sic.method_entry();
1382   oop* v = (oop*) klass->end_of_itable();
1383   assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1384 #endif
1385 }
1386 
1387 
1388 // inverse to itable_index
1389 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1390   assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1391   assert(intf->verify_itable_index(itable_index), "");
1392   Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1393 
1394   if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1395     return NULL;                // help caller defend against bad indices
1396 
1397   int index = itable_index;
1398   Method* m = methods->at(index);
1399   int index2 = -1;
1400   while (!m->has_itable_index() ||
1401          (index2 = m->itable_index()) != itable_index) {
1402     assert(index2 < itable_index, "monotonic");
1403     if (++index == methods->length())
1404       return NULL;
1405     m = methods->at(index);
1406   }
1407   assert(m->itable_index() == itable_index, "correct inverse");
1408 
1409   return m;
1410 }
1411 
1412 void klassVtable::verify(outputStream* st, bool forced) {
1413   // make sure table is initialized
1414   if (!Universe::is_fully_initialized()) return;
1415 #ifndef PRODUCT
1416   // avoid redundant verifies
1417   if (!forced && _verify_count == Universe::verify_count()) return;
1418   _verify_count = Universe::verify_count();
1419 #endif
1420   oop* end_of_obj = (oop*)_klass() + _klass()->size();
1421   oop* end_of_vtable = (oop *)&table()[_length];
1422   if (end_of_vtable > end_of_obj) {
1423     fatal(err_msg("klass %s: klass object too short (vtable extends beyond "
1424                   "end)", _klass->internal_name()));
1425   }
1426 
1427   for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1428   // verify consistency with superKlass vtable
1429   Klass* super = _klass->super();
1430   if (super != NULL) {
1431     InstanceKlass* sk = InstanceKlass::cast(super);
1432     klassVtable* vt = sk->vtable();
1433     for (int i = 0; i < vt->length(); i++) {
1434       verify_against(st, vt, i);
1435     }
1436   }
1437 }
1438 
1439 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1440   vtableEntry* vte = &vt->table()[index];
1441   if (vte->method()->name()      != table()[index].method()->name() ||
1442       vte->method()->signature() != table()[index].method()->signature()) {
1443     fatal("mismatched name/signature of vtable entries");
1444   }
1445 }
1446 
1447 #ifndef PRODUCT
1448 void klassVtable::print() {
1449   ResourceMark rm;
1450   tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1451   for (int i = 0; i < length(); i++) {
1452     table()[i].print();
1453     tty->cr();
1454   }
1455 }
1456 #endif
1457 
1458 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1459   NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1460   assert(method() != NULL, "must have set method");
1461   method()->verify();
1462   // we sub_type, because it could be a miranda method
1463   if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1464 #ifndef PRODUCT
1465     print();
1466 #endif
1467     fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
1468   }
1469 }
1470 
1471 #ifndef PRODUCT
1472 
1473 void vtableEntry::print() {
1474   ResourceMark rm;
1475   tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1476   if (Verbose) {
1477     tty->print("m %#lx ", (address)method());
1478   }
1479 }
1480 
1481 class VtableStats : AllStatic {
1482  public:
1483   static int no_klasses;                // # classes with vtables
1484   static int no_array_klasses;          // # array classes
1485   static int no_instance_klasses;       // # instanceKlasses
1486   static int sum_of_vtable_len;         // total # of vtable entries
1487   static int sum_of_array_vtable_len;   // total # of vtable entries in array klasses only
1488   static int fixed;                     // total fixed overhead in bytes
1489   static int filler;                    // overhead caused by filler bytes
1490   static int entries;                   // total bytes consumed by vtable entries
1491   static int array_entries;             // total bytes consumed by array vtable entries
1492 
1493   static void do_class(Klass* k) {
1494     Klass* kl = k;
1495     klassVtable* vt = kl->vtable();
1496     if (vt == NULL) return;
1497     no_klasses++;
1498     if (kl->oop_is_instance()) {
1499       no_instance_klasses++;
1500       kl->array_klasses_do(do_class);
1501     }
1502     if (kl->oop_is_array()) {
1503       no_array_klasses++;
1504       sum_of_array_vtable_len += vt->length();
1505     }
1506     sum_of_vtable_len += vt->length();
1507   }
1508 
1509   static void compute() {
1510     SystemDictionary::classes_do(do_class);
1511     fixed  = no_klasses * oopSize;      // vtable length
1512     // filler size is a conservative approximation
1513     filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1514     entries = sizeof(vtableEntry) * sum_of_vtable_len;
1515     array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1516   }
1517 };
1518 
1519 int VtableStats::no_klasses = 0;
1520 int VtableStats::no_array_klasses = 0;
1521 int VtableStats::no_instance_klasses = 0;
1522 int VtableStats::sum_of_vtable_len = 0;
1523 int VtableStats::sum_of_array_vtable_len = 0;
1524 int VtableStats::fixed = 0;
1525 int VtableStats::filler = 0;
1526 int VtableStats::entries = 0;
1527 int VtableStats::array_entries = 0;
1528 
1529 void klassVtable::print_statistics() {
1530   ResourceMark rm;
1531   HandleMark hm;
1532   VtableStats::compute();
1533   tty->print_cr("vtable statistics:");
1534   tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1535   int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1536   tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1537   tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1538   tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1539   tty->print_cr("%6d bytes total", total);
1540 }
1541 
1542 int  klassItable::_total_classes;   // Total no. of classes with itables
1543 long klassItable::_total_size;      // Total no. of bytes used for itables
1544 
1545 void klassItable::print_statistics() {
1546  tty->print_cr("itable statistics:");
1547  tty->print_cr("%6d classes with itables", _total_classes);
1548  tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes);
1549 }
1550 
1551 #endif // PRODUCT