1 /*
   2  * Copyright (c) 1997, 2013, 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 inline InstanceKlass* klassVtable::ik() const {
  43   Klass* k = _klass();
  44   assert(k->oop_is_instance(), "not an InstanceKlass");
  45   return (InstanceKlass*)k;
  46 }
  47 
  48 
  49 // this function computes the vtable size (including the size needed for miranda
  50 // methods) and the number of miranda methods in this class
  51 // Note on Miranda methods: Let's say there is a class C that implements
  52 // interface I.  Let's say there is a method m in I that neither C nor any
  53 // of its super classes implement (i.e there is no method of any access, with
  54 // the same name and signature as m), then m is a Miranda method which is
  55 // entered as a public abstract method in C's vtable.  From then on it should
  56 // treated as any other public method in C for method over-ride purposes.
  57 void klassVtable::compute_vtable_size_and_num_mirandas(
  58     int* vtable_length_ret, int* num_new_mirandas,
  59     GrowableArray<Method*>* all_mirandas, Klass* super,
  60     Array<Method*>* methods, AccessFlags class_flags,
  61     Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
  62     TRAPS) {
  63   No_Safepoint_Verifier nsv;
  64 
  65   // set up default result values
  66   int vtable_length = 0;
  67 
  68   // start off with super's vtable length
  69   InstanceKlass* sk = (InstanceKlass*)super;
  70   vtable_length = super == NULL ? 0 : sk->vtable_length();
  71 
  72   // go thru each method in the methods table to see if it needs a new entry
  73   int len = methods->length();
  74   for (int i = 0; i < len; i++) {
  75     assert(methods->at(i)->is_method(), "must be a Method*");
  76     methodHandle mh(THREAD, methods->at(i));
  77 
  78     if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) {
  79       vtable_length += vtableEntry::size(); // we need a new entry
  80     }
  81   }
  82 
  83   GrowableArray<Method*> new_mirandas(20);
  84   // compute the number of mirandas methods that must be added to the end
  85   get_mirandas(&new_mirandas, all_mirandas, super, methods, local_interfaces);
  86   *num_new_mirandas = new_mirandas.length();
  87 
  88   vtable_length += *num_new_mirandas * vtableEntry::size();
  89 
  90   if (Universe::is_bootstrapping() && vtable_length == 0) {
  91     // array classes don't have their superclass set correctly during
  92     // bootstrapping
  93     vtable_length = Universe::base_vtable_size();
  94   }
  95 
  96   if (super == NULL && !Universe::is_bootstrapping() &&
  97       vtable_length != Universe::base_vtable_size()) {
  98     // Someone is attempting to redefine java.lang.Object incorrectly.  The
  99     // only way this should happen is from
 100     // SystemDictionary::resolve_from_stream(), which will detect this later
 101     // and throw a security exception.  So don't assert here to let
 102     // the exception occur.
 103     vtable_length = Universe::base_vtable_size();
 104   }
 105   assert(super != NULL || vtable_length == Universe::base_vtable_size(),
 106          "bad vtable size for class Object");
 107   assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
 108   assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
 109 
 110   *vtable_length_ret = vtable_length;
 111 }
 112 
 113 int klassVtable::index_of(Method* m, int len) const {
 114   assert(m->vtable_index() >= 0, "do not ask this of non-vtable methods");
 115   return m->vtable_index();
 116 }
 117 
 118 int klassVtable::initialize_from_super(KlassHandle super) {
 119   if (super.is_null()) {
 120     return 0;
 121   } else {
 122     // copy methods from superKlass
 123     // can't inherit from array class, so must be InstanceKlass
 124     assert(super->oop_is_instance(), "must be instance klass");
 125     InstanceKlass* sk = (InstanceKlass*)super();
 126     klassVtable* superVtable = sk->vtable();
 127     assert(superVtable->length() <= _length, "vtable too short");
 128 #ifdef ASSERT
 129     superVtable->verify(tty, true);
 130 #endif
 131     superVtable->copy_vtable_to(table());
 132 #ifndef PRODUCT
 133     if (PrintVtables && Verbose) {
 134       ResourceMark rm;
 135       tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length);
 136     }
 137 #endif
 138     return superVtable->length();
 139   }
 140 }
 141 
 142 // Revised lookup semantics   introduced 1.3 (Kestral beta)
 143 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
 144 
 145   // Note:  Arrays can have intermediate array supers.  Use java_super to skip them.
 146   KlassHandle super (THREAD, klass()->java_super());
 147   int nofNewEntries = 0;
 148 
 149 
 150   if (PrintVtables && !klass()->oop_is_array()) {
 151     ResourceMark rm(THREAD);
 152     tty->print_cr("Initializing: %s", _klass->name()->as_C_string());
 153   }
 154 
 155 #ifdef ASSERT
 156   oop* end_of_obj = (oop*)_klass() + _klass()->size();
 157   oop* end_of_vtable = (oop*)&table()[_length];
 158   assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
 159 #endif
 160 
 161   if (Universe::is_bootstrapping()) {
 162     // just clear everything
 163     for (int i = 0; i < _length; i++) table()[i].clear();
 164     return;
 165   }
 166 
 167   int super_vtable_len = initialize_from_super(super);
 168   if (klass()->oop_is_array()) {
 169     assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
 170   } else {
 171     assert(_klass->oop_is_instance(), "must be InstanceKlass");
 172 
 173     Array<Method*>* methods = ik()->methods();
 174     int len = methods->length();
 175     int initialized = super_vtable_len;
 176 
 177     // update_inherited_vtable can stop for gc - ensure using handles
 178     for (int i = 0; i < len; i++) {
 179       HandleMark hm(THREAD);
 180       assert(methods->at(i)->is_method(), "must be a Method*");
 181       methodHandle mh(THREAD, methods->at(i));
 182 
 183       bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, checkconstraints, CHECK);
 184 
 185       if (needs_new_entry) {
 186         put_method_at(mh(), initialized);
 187         mh()->set_vtable_index(initialized); // set primary vtable index
 188         initialized++;
 189       }
 190     }
 191 
 192     // add miranda methods; it will also update the value of initialized
 193     fill_in_mirandas(&initialized);
 194 
 195     // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
 196     // package_private -> publicprotected), the vtable might actually be smaller than our initial
 197     // calculation.
 198     assert(initialized <= _length, "vtable initialization failed");
 199     for(;initialized < _length; initialized++) {
 200       put_method_at(NULL, initialized);
 201     }
 202     NOT_PRODUCT(verify(tty, true));
 203   }
 204 }
 205 
 206 // Called for cases where a method does not override its superclass' vtable entry
 207 // For bytecodes not produced by javac together it is possible that a method does not override
 208 // the superclass's method, but might indirectly override a super-super class's vtable entry
 209 // If none found, return a null superk, else return the superk of the method this does override
 210 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
 211                             int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
 212   InstanceKlass* superk = initialsuper;
 213   while (superk != NULL && superk->super() != NULL) {
 214     InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
 215     klassVtable* ssVtable = supersuperklass->vtable();
 216     if (vtable_index < ssVtable->length()) {
 217       Method* super_method = ssVtable->method_at(vtable_index);
 218 #ifndef PRODUCT
 219       Symbol* name= target_method()->name();
 220       Symbol* signature = target_method()->signature();
 221       assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
 222 #endif
 223       if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
 224 #ifndef PRODUCT
 225         if (PrintVtables && Verbose) {
 226           ResourceMark rm(THREAD);
 227           tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
 228            supersuperklass->internal_name(),
 229            _klass->internal_name(), (target_method() != NULL) ?
 230            target_method()->name()->as_C_string() : "<NULL>", vtable_index);
 231            super_method->access_flags().print_on(tty);
 232            tty->print("overriders flags: ");
 233            target_method->access_flags().print_on(tty);
 234            tty->cr();
 235         }
 236 #endif /*PRODUCT*/
 237         break; // return found superk
 238       }
 239     } else  {
 240       // super class has no vtable entry here, stop transitive search
 241       superk = (InstanceKlass*)NULL;
 242       break;
 243     }
 244     // if no override found yet, continue to search up
 245     superk = InstanceKlass::cast(superk->super());
 246   }
 247 
 248   return superk;
 249 }
 250 
 251 // Methods that are "effectively" final don't need vtable entries.
 252 bool method_is_effectively_final(
 253     AccessFlags klass_flags, methodHandle target) {
 254   return target->is_final() || klass_flags.is_final() && !target->is_overpass();
 255 }
 256 
 257 // Update child's copy of super vtable for overrides
 258 // OR return true if a new vtable entry is required
 259 // Only called for InstanceKlass's, i.e. not for arrays
 260 // If that changed, could not use _klass as handle for klass
 261 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, int super_vtable_len,
 262                   bool checkconstraints, TRAPS) {
 263   ResourceMark rm;
 264   bool allocate_new = true;
 265   assert(klass->oop_is_instance(), "must be InstanceKlass");
 266 
 267   // Initialize the method's vtable index to "nonvirtual".
 268   // If we allocate a vtable entry, we will update it to a non-negative number.
 269   target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
 270 
 271   // Static and <init> methods are never in
 272   if (target_method()->is_static() || target_method()->name() ==  vmSymbols::object_initializer_name()) {
 273     return false;
 274   }
 275 
 276   if (method_is_effectively_final(klass->access_flags(), target_method)) {
 277     // a final method never needs a new entry; final methods can be statically
 278     // resolved and they have to be present in the vtable only if they override
 279     // a super's method, in which case they re-use its entry
 280     allocate_new = false;
 281   }
 282 
 283   // we need a new entry if there is no superclass
 284   if (klass->super() == NULL) {
 285     return allocate_new;
 286   }
 287 
 288   // private methods always have a new entry in the vtable
 289   // specification interpretation since classic has
 290   // private methods not overriding
 291   if (target_method()->is_private()) {
 292     return allocate_new;
 293   }
 294 
 295   // search through the vtable and update overridden entries
 296   // Since check_signature_loaders acquires SystemDictionary_lock
 297   // which can block for gc, once we are in this loop, use handles
 298   // For classfiles built with >= jdk7, we now look for transitive overrides
 299 
 300   Symbol* name = target_method()->name();
 301   Symbol* signature = target_method()->signature();
 302   Handle target_loader(THREAD, _klass()->class_loader());
 303   Symbol*  target_classname = _klass->name();
 304   for(int i = 0; i < super_vtable_len; i++) {
 305     Method* super_method = method_at(i);
 306     // Check if method name matches
 307     if (super_method->name() == name && super_method->signature() == signature) {
 308 
 309       // get super_klass for method_holder for the found method
 310       InstanceKlass* super_klass =  super_method->method_holder();
 311 
 312       if ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) ||
 313       ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
 314         && ((super_klass = find_transitive_override(super_klass, target_method, i, target_loader,
 315              target_classname, THREAD)) != (InstanceKlass*)NULL))) {
 316         // overriding, so no new entry
 317         allocate_new = false;
 318 
 319         if (checkconstraints) {
 320         // Override vtable entry if passes loader constraint check
 321         // if loader constraint checking requested
 322         // No need to visit his super, since he and his super
 323         // have already made any needed loader constraints.
 324         // Since loader constraints are transitive, it is enough
 325         // to link to the first super, and we get all the others.
 326           Handle super_loader(THREAD, super_klass->class_loader());
 327 
 328           if (target_loader() != super_loader()) {
 329             ResourceMark rm(THREAD);
 330             char* failed_type_name =
 331               SystemDictionary::check_signature_loaders(signature, target_loader,
 332                                                         super_loader, true,
 333                                                         CHECK_(false));
 334             if (failed_type_name != NULL) {
 335               const char* msg = "loader constraint violation: when resolving "
 336                 "overridden method \"%s\" the class loader (instance"
 337                 " of %s) of the current class, %s, and its superclass loader "
 338                 "(instance of %s), have different Class objects for the type "
 339                 "%s used in the signature";
 340               char* sig = target_method()->name_and_sig_as_C_string();
 341               const char* loader1 = SystemDictionary::loader_name(target_loader());
 342               char* current = _klass->name()->as_C_string();
 343               const char* loader2 = SystemDictionary::loader_name(super_loader());
 344               size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
 345                 strlen(current) + strlen(loader2) + strlen(failed_type_name);
 346               char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
 347               jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
 348                            failed_type_name);
 349               THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
 350             }
 351           }
 352        }
 353 
 354         put_method_at(target_method(), i);
 355         target_method()->set_vtable_index(i);
 356 #ifndef PRODUCT
 357         if (PrintVtables && Verbose) {
 358           tty->print("overriding with %s::%s index %d, original flags: ",
 359            _klass->internal_name(), (target_method() != NULL) ?
 360            target_method()->name()->as_C_string() : "<NULL>", i);
 361            super_method->access_flags().print_on(tty);
 362            tty->print("overriders flags: ");
 363            target_method->access_flags().print_on(tty);
 364            tty->cr();
 365         }
 366 #endif /*PRODUCT*/
 367       } else {
 368         // allocate_new = true; default. We might override one entry,
 369         // but not override another. Once we override one, not need new
 370 #ifndef PRODUCT
 371         if (PrintVtables && Verbose) {
 372           tty->print("NOT overriding with %s::%s index %d, original flags: ",
 373            _klass->internal_name(), (target_method() != NULL) ?
 374            target_method()->name()->as_C_string() : "<NULL>", i);
 375            super_method->access_flags().print_on(tty);
 376            tty->print("overriders flags: ");
 377            target_method->access_flags().print_on(tty);
 378            tty->cr();
 379         }
 380 #endif /*PRODUCT*/
 381       }
 382     }
 383   }
 384   return allocate_new;
 385 }
 386 
 387 void klassVtable::put_method_at(Method* m, int index) {
 388 #ifndef PRODUCT
 389   if (PrintVtables && Verbose) {
 390     ResourceMark rm;
 391     tty->print_cr("adding %s::%s at index %d", _klass->internal_name(),
 392       (m != NULL) ? m->name()->as_C_string() : "<NULL>", index);
 393   }
 394 #endif
 395   table()[index].set(m);
 396 }
 397 
 398 // Find out if a method "m" with superclass "super", loader "classloader" and
 399 // name "classname" needs a new vtable entry.  Let P be a class package defined
 400 // by "classloader" and "classname".
 401 // NOTE: The logic used here is very similar to the one used for computing
 402 // the vtables indices for a method. We cannot directly use that function because,
 403 // we allocate the InstanceKlass at load time, and that requires that the
 404 // superclass has been loaded.
 405 // However, the vtable entries are filled in at link time, and therefore
 406 // the superclass' vtable may not yet have been filled in.
 407 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
 408                                          Klass* super,
 409                                          Handle classloader,
 410                                          Symbol* classname,
 411                                          AccessFlags class_flags,
 412                                          TRAPS) {
 413 
 414   if (method_is_effectively_final(class_flags, target_method) ||
 415       // a final method never needs a new entry; final methods can be statically
 416       // resolved and they have to be present in the vtable only if they override
 417       // a super's method, in which case they re-use its entry
 418       (target_method()->is_static()) ||
 419       // static methods don't need to be in vtable
 420       (target_method()->name() ==  vmSymbols::object_initializer_name())
 421       // <init> is never called dynamically-bound
 422       ) {
 423     return false;
 424   }
 425 
 426   // we need a new entry if there is no superclass
 427   if (super == NULL) {
 428     return true;
 429   }
 430 
 431   // private methods always have a new entry in the vtable
 432   // specification interpretation since classic has
 433   // private methods not overriding
 434   if (target_method()->is_private()) {
 435     return true;
 436   }
 437 
 438   // search through the super class hierarchy to see if we need
 439   // a new entry
 440   ResourceMark rm;
 441   Symbol* name = target_method()->name();
 442   Symbol* signature = target_method()->signature();
 443   Klass* k = super;
 444   Method* super_method = NULL;
 445   InstanceKlass *holder = NULL;
 446   Method* recheck_method =  NULL;
 447   while (k != NULL) {
 448     // lookup through the hierarchy for a method with matching name and sign.
 449     super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
 450     if (super_method == NULL) {
 451       break; // we still have to search for a matching miranda method
 452     }
 453     // get the class holding the matching method
 454     // make sure you use that class for is_override
 455     InstanceKlass* superk = super_method->method_holder();
 456     // we want only instance method matches
 457     // pretend private methods are not in the super vtable
 458     // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
 459     // ignore private, c.m pub does override a.m pub
 460     // For classes that were not javac'd together, we also do transitive overriding around
 461     // methods that have less accessibility
 462     if ((!super_method->is_static()) &&
 463        (!super_method->is_private())) {
 464       if (superk->is_override(super_method, classloader, classname, THREAD)) {
 465         return false;
 466       // else keep looking for transitive overrides
 467       }
 468     }
 469 
 470     // Start with lookup result and continue to search up
 471     k = superk->super(); // haven't found an override match yet; continue to look
 472   }
 473 
 474   // if the target method is public or protected it may have a matching
 475   // miranda method in the super, whose entry it should re-use.
 476   // Actually, to handle cases that javac would not generate, we need
 477   // this check for all access permissions.
 478   InstanceKlass *sk = InstanceKlass::cast(super);
 479   if (sk->has_miranda_methods()) {
 480     if (sk->lookup_method_in_all_interfaces(name, signature) != NULL) {
 481       return false;  // found a matching miranda; we do not need a new entry
 482     }
 483   }
 484   return true; // found no match; we need a new entry
 485 }
 486 
 487 // Support for miranda methods
 488 
 489 // get the vtable index of a miranda method with matching "name" and "signature"
 490 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
 491   // search from the bottom, might be faster
 492   for (int i = (length() - 1); i >= 0; i--) {
 493     Method* m = table()[i].method();
 494     if (is_miranda_entry_at(i) &&
 495         m->name() == name && m->signature() == signature) {
 496       return i;
 497     }
 498   }
 499   return Method::invalid_vtable_index;
 500 }
 501 
 502 // check if an entry is miranda
 503 bool klassVtable::is_miranda_entry_at(int i) {
 504   Method* m = method_at(i);
 505   Klass* method_holder = m->method_holder();
 506   InstanceKlass *mhk = InstanceKlass::cast(method_holder);
 507 
 508   // miranda methods are interface methods in a class's vtable
 509   if (mhk->is_interface()) {
 510     assert(m->is_public(), "should be public");
 511     assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
 512     assert(is_miranda(m, ik()->methods(), ik()->super()), "should be a miranda_method");
 513     return true;
 514   }
 515   return false;
 516 }
 517 
 518 // check if a method is a miranda method, given a class's methods table and it's super
 519 // the caller must make sure that the method belongs to an interface implemented by the class
 520 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, Klass* super) {
 521   Symbol* name = m->name();
 522   Symbol* signature = m->signature();
 523   if (InstanceKlass::find_method(class_methods, name, signature) == NULL) {
 524     // did not find it in the method table of the current class
 525     if (super == NULL) {
 526       // super doesn't exist
 527       return true;
 528     }
 529 
 530     Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature);
 531     if (mo == NULL || mo->access_flags().is_private() ) {
 532       // super class hierarchy does not implement it or protection is different
 533       return true;
 534     }
 535   }
 536 
 537   return false;
 538 }
 539 
 540 void klassVtable::add_new_mirandas_to_lists(
 541     GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
 542     Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
 543     Klass* super) {
 544   // iterate thru the current interface's method to see if it a miranda
 545   int num_methods = current_interface_methods->length();
 546   for (int i = 0; i < num_methods; i++) {
 547     Method* im = current_interface_methods->at(i);
 548     bool is_duplicate = false;
 549     int num_of_current_mirandas = new_mirandas->length();
 550     // check for duplicate mirandas in different interfaces we implement
 551     for (int j = 0; j < num_of_current_mirandas; j++) {
 552       Method* miranda = new_mirandas->at(j);
 553       if ((im->name() == miranda->name()) &&
 554           (im->signature() == miranda->signature())) {
 555         is_duplicate = true;
 556         break;
 557       }
 558     }
 559 
 560     if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
 561       if (is_miranda(im, class_methods, super)) { // is it a miranda at all?
 562         InstanceKlass *sk = InstanceKlass::cast(super);
 563         // check if it is a duplicate of a super's miranda
 564         if (sk->lookup_method_in_all_interfaces(im->name(), im->signature()) == NULL) {
 565           new_mirandas->append(im);
 566         }
 567         if (all_mirandas != NULL) {
 568           all_mirandas->append(im);
 569         }
 570       }
 571     }
 572   }
 573 }
 574 
 575 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
 576                                GrowableArray<Method*>* all_mirandas,
 577                                Klass* super, Array<Method*>* class_methods,
 578                                Array<Klass*>* local_interfaces) {
 579   assert((new_mirandas->length() == 0) , "current mirandas must be 0");
 580 
 581   // iterate thru the local interfaces looking for a miranda
 582   int num_local_ifs = local_interfaces->length();
 583   for (int i = 0; i < num_local_ifs; i++) {
 584     InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
 585     add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 586                               ik->methods(), class_methods, super);
 587     // iterate thru each local's super interfaces
 588     Array<Klass*>* super_ifs = ik->transitive_interfaces();
 589     int num_super_ifs = super_ifs->length();
 590     for (int j = 0; j < num_super_ifs; j++) {
 591       InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
 592       add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 593                                 sik->methods(), class_methods, super);
 594     }
 595   }
 596 }
 597 
 598 // fill in mirandas
 599 void klassVtable::fill_in_mirandas(int* initialized) {
 600   GrowableArray<Method*> mirandas(20);
 601   get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
 602                ik()->local_interfaces());
 603   for (int i = 0; i < mirandas.length(); i++) {
 604     put_method_at(mirandas.at(i), *initialized);
 605     ++(*initialized);
 606   }
 607 }
 608 
 609 void klassVtable::copy_vtable_to(vtableEntry* start) {
 610   Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
 611 }
 612 
 613 void klassVtable::adjust_method_entries(Method** old_methods, Method** new_methods,
 614                                         int methods_length, bool * trace_name_printed) {
 615   // search the vtable for uses of either obsolete or EMCP methods
 616   for (int j = 0; j < methods_length; j++) {
 617     Method* old_method = old_methods[j];
 618     Method* new_method = new_methods[j];
 619 
 620     // In the vast majority of cases we could get the vtable index
 621     // by using:  old_method->vtable_index()
 622     // However, there are rare cases, eg. sun.awt.X11.XDecoratedPeer.getX()
 623     // in sun.awt.X11.XFramePeer where methods occur more than once in the
 624     // vtable, so, alas, we must do an exhaustive search.
 625     for (int index = 0; index < length(); index++) {
 626       if (unchecked_method_at(index) == old_method) {
 627         put_method_at(new_method, index);
 628 
 629         if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
 630           if (!(*trace_name_printed)) {
 631             // RC_TRACE_MESG macro has an embedded ResourceMark
 632             RC_TRACE_MESG(("adjust: name=%s",
 633                            old_method->method_holder()->external_name()));
 634             *trace_name_printed = true;
 635           }
 636           // RC_TRACE macro has an embedded ResourceMark
 637           RC_TRACE(0x00100000, ("vtable method update: %s(%s)",
 638                                 new_method->name()->as_C_string(),
 639                                 new_method->signature()->as_C_string()));
 640         }
 641         // cannot 'break' here; see for-loop comment above.
 642       }
 643     }
 644   }
 645 }
 646 
 647 // a vtable should never contain old or obsolete methods
 648 bool klassVtable::check_no_old_or_obsolete_entries() {
 649   for (int i = 0; i < length(); i++) {
 650     Method* m = unchecked_method_at(i);
 651     if (m != NULL &&
 652         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
 653       return false;
 654     }
 655   }
 656   return true;
 657 }
 658 
 659 void klassVtable::dump_vtable() {
 660   tty->print_cr("vtable dump --");
 661   for (int i = 0; i < length(); i++) {
 662     Method* m = unchecked_method_at(i);
 663     if (m != NULL) {
 664       tty->print("      (%5d)  ", i);
 665       m->access_flags().print_on(tty);
 666       tty->print(" --  ");
 667       m->print_name(tty);
 668       tty->cr();
 669     }
 670   }
 671 }
 672 
 673 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
 674 void klassVtable::clear_vtable() {
 675   for (int i = 0; i < _length; i++) table()[i].clear();
 676 }
 677 
 678 bool klassVtable::is_initialized() {
 679   return _length == 0 || table()[0].method() != NULL;
 680 }
 681 
 682 //-----------------------------------------------------------------------------------------
 683 // Itable code
 684 
 685 // Initialize a itableMethodEntry
 686 void itableMethodEntry::initialize(Method* m) {
 687   if (m == NULL) return;
 688 
 689   _method = m;
 690 }
 691 
 692 klassItable::klassItable(instanceKlassHandle klass) {
 693   _klass = klass;
 694 
 695   if (klass->itable_length() > 0) {
 696     itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
 697     if (offset_entry  != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
 698       // First offset entry points to the first method_entry
 699       intptr_t* method_entry  = (intptr_t *)(((address)klass()) + offset_entry->offset());
 700       intptr_t* end         = klass->end_of_itable();
 701 
 702       _table_offset      = (intptr_t*)offset_entry - (intptr_t*)klass();
 703       _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
 704       _size_method_table = (end - method_entry)                  / itableMethodEntry::size();
 705       assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
 706       return;
 707     }
 708   }
 709 
 710   // The length of the itable was either zero, or it has not yet been initialized.
 711   _table_offset      = 0;
 712   _size_offset_table = 0;
 713   _size_method_table = 0;
 714 }
 715 
 716 static int initialize_count = 0;
 717 
 718 // Initialization
 719 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
 720   // Cannot be setup doing bootstrapping, interfaces don't have
 721   // itables, and klass with only ones entry have empty itables
 722   if (Universe::is_bootstrapping() ||
 723       _klass->is_interface() ||
 724       _klass->itable_length() == itableOffsetEntry::size()) return;
 725 
 726   // There's alway an extra itable entry so we can null-terminate it.
 727   guarantee(size_offset_table() >= 1, "too small");
 728   int num_interfaces = size_offset_table() - 1;
 729   if (num_interfaces > 0) {
 730     if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count,
 731                                     _klass->name()->as_C_string());
 732 
 733 
 734     // Iterate through all interfaces
 735     int i;
 736     for(i = 0; i < num_interfaces; i++) {
 737       itableOffsetEntry* ioe = offset_entry(i);
 738       HandleMark hm(THREAD);
 739       KlassHandle interf_h (THREAD, ioe->interface_klass());
 740       assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
 741       initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
 742     }
 743 
 744   }
 745   // Check that the last entry is empty
 746   itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
 747   guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
 748 }
 749 
 750 
 751 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
 752   Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();
 753   int nof_methods = methods->length();
 754   HandleMark hm;
 755   KlassHandle klass = _klass;
 756   assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
 757   Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader());
 758   int ime_num = 0;
 759 
 760   // Skip first Method* if it is a class initializer
 761   int i = methods->at(0)->is_static_initializer() ? 1 : 0;
 762 
 763   // m, method_name, method_signature, klass reset each loop so they
 764   // don't need preserving across check_signature_loaders call
 765   // methods needs a handle in case of gc from check_signature_loaders
 766   for(; i < nof_methods; i++) {
 767     Method* m = methods->at(i);
 768     Symbol* method_name = m->name();
 769     Symbol* method_signature = m->signature();
 770 
 771     // This is same code as in Linkresolver::lookup_instance_method_in_klasses
 772     Method* target = klass->uncached_lookup_method(method_name, method_signature);
 773     while (target != NULL && target->is_static()) {
 774       // continue with recursive lookup through the superclass
 775       Klass* super = target->method_holder()->super();
 776       target = (super == NULL) ? (Method*)NULL : super->uncached_lookup_method(method_name, method_signature);
 777     }
 778     if (target == NULL || !target->is_public() || target->is_abstract()) {
 779       // Entry do not resolve. Leave it empty
 780     } else {
 781       // Entry did resolve, check loader constraints before initializing
 782       // if checkconstraints requested
 783       methodHandle  target_h (THREAD, target); // preserve across gc
 784       if (checkconstraints) {
 785         Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
 786         if (method_holder_loader() != interface_loader()) {
 787           ResourceMark rm(THREAD);
 788           char* failed_type_name =
 789             SystemDictionary::check_signature_loaders(method_signature,
 790                                                       method_holder_loader,
 791                                                       interface_loader,
 792                                                       true, CHECK);
 793           if (failed_type_name != NULL) {
 794             const char* msg = "loader constraint violation in interface "
 795               "itable initialization: when resolving method \"%s\" the class"
 796               " loader (instance of %s) of the current class, %s, "
 797               "and the class loader (instance of %s) for interface "
 798               "%s have different Class objects for the type %s "
 799               "used in the signature";
 800             char* sig = target_h()->name_and_sig_as_C_string();
 801             const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
 802             char* current = klass->name()->as_C_string();
 803             const char* loader2 = SystemDictionary::loader_name(interface_loader());
 804             char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string();
 805             size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
 806               strlen(current) + strlen(loader2) + strlen(iface) +
 807               strlen(failed_type_name);
 808             char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
 809             jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
 810                          iface, failed_type_name);
 811             THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
 812           }
 813         }
 814       }
 815 
 816       // ime may have moved during GC so recalculate address
 817       itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target_h());
 818     }
 819     // Progress to next entry
 820     ime_num++;
 821   }
 822 }
 823 
 824 // Update entry for specific Method*
 825 void klassItable::initialize_with_method(Method* m) {
 826   itableMethodEntry* ime = method_entry(0);
 827   for(int i = 0; i < _size_method_table; i++) {
 828     if (ime->method() == m) {
 829       ime->initialize(m);
 830     }
 831     ime++;
 832   }
 833 }
 834 
 835 void klassItable::adjust_method_entries(Method** old_methods, Method** new_methods,
 836                                         int methods_length, bool * trace_name_printed) {
 837   // search the itable for uses of either obsolete or EMCP methods
 838   for (int j = 0; j < methods_length; j++) {
 839     Method* old_method = old_methods[j];
 840     Method* new_method = new_methods[j];
 841     itableMethodEntry* ime = method_entry(0);
 842 
 843     // The itable can describe more than one interface and the same
 844     // method signature can be specified by more than one interface.
 845     // This means we have to do an exhaustive search to find all the
 846     // old_method references.
 847     for (int i = 0; i < _size_method_table; i++) {
 848       if (ime->method() == old_method) {
 849         ime->initialize(new_method);
 850 
 851         if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
 852           if (!(*trace_name_printed)) {
 853             // RC_TRACE_MESG macro has an embedded ResourceMark
 854             RC_TRACE_MESG(("adjust: name=%s",
 855               old_method->method_holder()->external_name()));
 856             *trace_name_printed = true;
 857           }
 858           // RC_TRACE macro has an embedded ResourceMark
 859           RC_TRACE(0x00200000, ("itable method update: %s(%s)",
 860             new_method->name()->as_C_string(),
 861             new_method->signature()->as_C_string()));
 862         }
 863         // cannot 'break' here; see for-loop comment above.
 864       }
 865       ime++;
 866     }
 867   }
 868 }
 869 
 870 // an itable should never contain old or obsolete methods
 871 bool klassItable::check_no_old_or_obsolete_entries() {
 872   itableMethodEntry* ime = method_entry(0);
 873   for (int i = 0; i < _size_method_table; i++) {
 874     Method* m = ime->method();
 875     if (m != NULL &&
 876         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
 877       return false;
 878     }
 879     ime++;
 880   }
 881   return true;
 882 }
 883 
 884 void klassItable::dump_itable() {
 885   itableMethodEntry* ime = method_entry(0);
 886   tty->print_cr("itable dump --");
 887   for (int i = 0; i < _size_method_table; i++) {
 888     Method* m = ime->method();
 889     if (m != NULL) {
 890       tty->print("      (%5d)  ", i);
 891       m->access_flags().print_on(tty);
 892       tty->print(" --  ");
 893       m->print_name(tty);
 894       tty->cr();
 895     }
 896     ime++;
 897   }
 898 }
 899 
 900 
 901 // Setup
 902 class InterfaceVisiterClosure : public StackObj {
 903  public:
 904   virtual void doit(Klass* intf, int method_count) = 0;
 905 };
 906 
 907 // Visit all interfaces with at-least one method (excluding <clinit>)
 908 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
 909   // Handle array argument
 910   for(int i = 0; i < transitive_intf->length(); i++) {
 911     Klass* intf = transitive_intf->at(i);
 912     assert(intf->is_interface(), "sanity check");
 913 
 914     // Find no. of methods excluding a <clinit>
 915     int method_count = InstanceKlass::cast(intf)->methods()->length();
 916     if (method_count > 0) {
 917       Method* m = InstanceKlass::cast(intf)->methods()->at(0);
 918       assert(m != NULL && m->is_method(), "sanity check");
 919       if (m->name() == vmSymbols::object_initializer_name()) {
 920         method_count--;
 921       }
 922     }
 923 
 924     // Only count interfaces with at least one method
 925     if (method_count > 0) {
 926       blk->doit(intf, method_count);
 927     }
 928   }
 929 }
 930 
 931 class CountInterfacesClosure : public InterfaceVisiterClosure {
 932  private:
 933   int _nof_methods;
 934   int _nof_interfaces;
 935  public:
 936    CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
 937 
 938    int nof_methods() const    { return _nof_methods; }
 939    int nof_interfaces() const { return _nof_interfaces; }
 940 
 941    void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
 942 };
 943 
 944 class SetupItableClosure : public InterfaceVisiterClosure  {
 945  private:
 946   itableOffsetEntry* _offset_entry;
 947   itableMethodEntry* _method_entry;
 948   address            _klass_begin;
 949  public:
 950   SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
 951     _klass_begin  = klass_begin;
 952     _offset_entry = offset_entry;
 953     _method_entry = method_entry;
 954   }
 955 
 956   itableMethodEntry* method_entry() const { return _method_entry; }
 957 
 958   void doit(Klass* intf, int method_count) {
 959     int offset = ((address)_method_entry) - _klass_begin;
 960     _offset_entry->initialize(intf, offset);
 961     _offset_entry++;
 962     _method_entry += method_count;
 963   }
 964 };
 965 
 966 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
 967   // Count no of interfaces and total number of interface methods
 968   CountInterfacesClosure cic;
 969   visit_all_interfaces(transitive_interfaces, &cic);
 970 
 971   // There's alway an extra itable entry so we can null-terminate it.
 972   int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
 973 
 974   // Statistics
 975   update_stats(itable_size * HeapWordSize);
 976 
 977   return itable_size;
 978 }
 979 
 980 
 981 // Fill out offset table and interface klasses into the itable space
 982 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
 983   if (klass->itable_length() == 0) return;
 984   assert(!klass->is_interface(), "Should have zero length itable");
 985 
 986   // Count no of interfaces and total number of interface methods
 987   CountInterfacesClosure cic;
 988   visit_all_interfaces(klass->transitive_interfaces(), &cic);
 989   int nof_methods    = cic.nof_methods();
 990   int nof_interfaces = cic.nof_interfaces();
 991 
 992   // Add one extra entry so we can null-terminate the table
 993   nof_interfaces++;
 994 
 995   assert(compute_itable_size(klass->transitive_interfaces()) ==
 996          calc_itable_size(nof_interfaces, nof_methods),
 997          "mismatch calculation of itable size");
 998 
 999   // Fill-out offset table
1000   itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1001   itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1002   intptr_t* end               = klass->end_of_itable();
1003   assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1004   assert((oop*)(end) == (oop*)(ime + nof_methods),                      "wrong offset calculation (2)");
1005 
1006   // Visit all interfaces and initialize itable offset table
1007   SetupItableClosure sic((address)klass(), ioe, ime);
1008   visit_all_interfaces(klass->transitive_interfaces(), &sic);
1009 
1010 #ifdef ASSERT
1011   ime  = sic.method_entry();
1012   oop* v = (oop*) klass->end_of_itable();
1013   assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1014 #endif
1015 }
1016 
1017 
1018 // m must be a method in an interface
1019 int klassItable::compute_itable_index(Method* m) {
1020   InstanceKlass* intf = m->method_holder();
1021   assert(intf->is_interface(), "sanity check");
1022   Array<Method*>* methods = intf->methods();
1023   int index = 0;
1024   while(methods->at(index) != m) {
1025     index++;
1026     assert(index < methods->length(), "should find index for resolve_invoke");
1027   }
1028   // Adjust for <clinit>, which is left out of table if first method
1029   if (methods->length() > 0 && methods->at(0)->is_static_initializer()) {
1030     index--;
1031   }
1032   return index;
1033 }
1034 
1035 
1036 // inverse to compute_itable_index
1037 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1038   assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1039   Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1040 
1041   int index = itable_index;
1042   // Adjust for <clinit>, which is left out of table if first method
1043   if (methods->length() > 0 && methods->at(0)->is_static_initializer()) {
1044     index++;
1045   }
1046 
1047   if (itable_index < 0 || index >= methods->length())
1048     return NULL;                // help caller defend against bad indexes
1049 
1050   Method* m = methods->at(index);
1051   assert(compute_itable_index(m) == itable_index, "correct inverse");
1052 
1053   return m;
1054 }
1055 
1056 void klassVtable::verify(outputStream* st, bool forced) {
1057   // make sure table is initialized
1058   if (!Universe::is_fully_initialized()) return;
1059 #ifndef PRODUCT
1060   // avoid redundant verifies
1061   if (!forced && _verify_count == Universe::verify_count()) return;
1062   _verify_count = Universe::verify_count();
1063 #endif
1064   oop* end_of_obj = (oop*)_klass() + _klass()->size();
1065   oop* end_of_vtable = (oop *)&table()[_length];
1066   if (end_of_vtable > end_of_obj) {
1067     fatal(err_msg("klass %s: klass object too short (vtable extends beyond "
1068                   "end)", _klass->internal_name()));
1069   }
1070 
1071   for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1072   // verify consistency with superKlass vtable
1073   Klass* super = _klass->super();
1074   if (super != NULL) {
1075     InstanceKlass* sk = InstanceKlass::cast(super);
1076     klassVtable* vt = sk->vtable();
1077     for (int i = 0; i < vt->length(); i++) {
1078       verify_against(st, vt, i);
1079     }
1080   }
1081 }
1082 
1083 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1084   vtableEntry* vte = &vt->table()[index];
1085   if (vte->method()->name()      != table()[index].method()->name() ||
1086       vte->method()->signature() != table()[index].method()->signature()) {
1087     fatal("mismatched name/signature of vtable entries");
1088   }
1089 }
1090 
1091 #ifndef PRODUCT
1092 void klassVtable::print() {
1093   ResourceMark rm;
1094   tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1095   for (int i = 0; i < length(); i++) {
1096     table()[i].print();
1097     tty->cr();
1098   }
1099 }
1100 #endif
1101 
1102 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1103   NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1104   assert(method() != NULL, "must have set method");
1105   method()->verify();
1106   // we sub_type, because it could be a miranda method
1107   if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1108 #ifndef PRODUCT
1109     print();
1110 #endif
1111     fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
1112   }
1113 }
1114 
1115 #ifndef PRODUCT
1116 
1117 void vtableEntry::print() {
1118   ResourceMark rm;
1119   tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1120   if (Verbose) {
1121     tty->print("m %#lx ", (address)method());
1122   }
1123 }
1124 
1125 class VtableStats : AllStatic {
1126  public:
1127   static int no_klasses;                // # classes with vtables
1128   static int no_array_klasses;          // # array classes
1129   static int no_instance_klasses;       // # instanceKlasses
1130   static int sum_of_vtable_len;         // total # of vtable entries
1131   static int sum_of_array_vtable_len;   // total # of vtable entries in array klasses only
1132   static int fixed;                     // total fixed overhead in bytes
1133   static int filler;                    // overhead caused by filler bytes
1134   static int entries;                   // total bytes consumed by vtable entries
1135   static int array_entries;             // total bytes consumed by array vtable entries
1136 
1137   static void do_class(Klass* k) {
1138     Klass* kl = k;
1139     klassVtable* vt = kl->vtable();
1140     if (vt == NULL) return;
1141     no_klasses++;
1142     if (kl->oop_is_instance()) {
1143       no_instance_klasses++;
1144       kl->array_klasses_do(do_class);
1145     }
1146     if (kl->oop_is_array()) {
1147       no_array_klasses++;
1148       sum_of_array_vtable_len += vt->length();
1149     }
1150     sum_of_vtable_len += vt->length();
1151   }
1152 
1153   static void compute() {
1154     SystemDictionary::classes_do(do_class);
1155     fixed  = no_klasses * oopSize;      // vtable length
1156     // filler size is a conservative approximation
1157     filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1158     entries = sizeof(vtableEntry) * sum_of_vtable_len;
1159     array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1160   }
1161 };
1162 
1163 int VtableStats::no_klasses = 0;
1164 int VtableStats::no_array_klasses = 0;
1165 int VtableStats::no_instance_klasses = 0;
1166 int VtableStats::sum_of_vtable_len = 0;
1167 int VtableStats::sum_of_array_vtable_len = 0;
1168 int VtableStats::fixed = 0;
1169 int VtableStats::filler = 0;
1170 int VtableStats::entries = 0;
1171 int VtableStats::array_entries = 0;
1172 
1173 void klassVtable::print_statistics() {
1174   ResourceMark rm;
1175   HandleMark hm;
1176   VtableStats::compute();
1177   tty->print_cr("vtable statistics:");
1178   tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1179   int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1180   tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1181   tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1182   tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1183   tty->print_cr("%6d bytes total", total);
1184 }
1185 
1186 int  klassItable::_total_classes;   // Total no. of classes with itables
1187 long klassItable::_total_size;      // Total no. of bytes used for itables
1188 
1189 void klassItable::print_statistics() {
1190  tty->print_cr("itable statistics:");
1191  tty->print_cr("%6d classes with itables", _total_classes);
1192  tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes);
1193 }
1194 
1195 #endif // PRODUCT