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/klassOop.hpp"
  34 #include "oops/klassVtable.hpp"
  35 #include "oops/methodOop.hpp"
  36 #include "oops/objArrayOop.hpp"
  37 #include "oops/oop.inline.hpp"
  38 #include "prims/jvmtiRedefineClassesTrace.hpp"
  39 #include "runtime/arguments.hpp"
  40 #include "runtime/handles.inline.hpp"
  41 #include "utilities/copy.hpp"
  42 
  43 inline instanceKlass* klassVtable::ik() const {
  44   Klass* k = _klass()->klass_part();
  45   assert(k->oop_is_instance(), "not an instanceKlass");
  46   return (instanceKlass*)k;
  47 }
  48 
  49 
  50 // this function computes the vtable size (including the size needed for miranda
  51 // methods) and the number of miranda methods in this class
  52 // Note on Miranda methods: Let's say there is a class C that implements
  53 // interface I.  Let's say there is a method m in I that neither C nor any
  54 // of its super classes implement (i.e there is no method of any access, with
  55 // the same name and signature as m), then m is a Miranda method which is
  56 // entered as a public abstract method in C's vtable.  From then on it should
  57 // treated as any other public method in C for method over-ride purposes.
  58 void klassVtable::compute_vtable_size_and_num_mirandas(int &vtable_length,
  59                                                        int &num_miranda_methods,
  60                                                        klassOop super,
  61                                                        objArrayOop methods,
  62                                                        AccessFlags class_flags,
  63                                                        Handle classloader,
  64                                                        Symbol* classname,
  65                                                        objArrayOop local_interfaces,
  66                                                        TRAPS
  67                                                        ) {
  68 
  69   No_Safepoint_Verifier nsv;
  70 
  71   // set up default result values
  72   vtable_length = 0;
  73   num_miranda_methods = 0;
  74 
  75   // start off with super's vtable length
  76   instanceKlass* sk = (instanceKlass*)super->klass_part();
  77   vtable_length = super == NULL ? 0 : sk->vtable_length();
  78 
  79   // go thru each method in the methods table to see if it needs a new entry
  80   int len = methods->length();
  81   for (int i = 0; i < len; i++) {
  82     assert(methods->obj_at(i)->is_method(), "must be a methodOop");
  83     methodHandle mh(THREAD, methodOop(methods->obj_at(i)));
  84 
  85     if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) {
  86       vtable_length += vtableEntry::size(); // we need a new entry
  87     }
  88   }
  89 
  90   // compute the number of mirandas methods that must be added to the end
  91   num_miranda_methods = get_num_mirandas(super, methods, local_interfaces);
  92   vtable_length += (num_miranda_methods * vtableEntry::size());
  93 
  94   if (Universe::is_bootstrapping() && vtable_length == 0) {
  95     // array classes don't have their superclass set correctly during
  96     // bootstrapping
  97     vtable_length = Universe::base_vtable_size();
  98   }
  99 
 100   if (super == NULL && !Universe::is_bootstrapping() &&
 101       vtable_length != Universe::base_vtable_size()) {
 102     // Someone is attempting to redefine java.lang.Object incorrectly.  The
 103     // only way this should happen is from
 104     // SystemDictionary::resolve_from_stream(), which will detect this later
 105     // and throw a security exception.  So don't assert here to let
 106     // the exception occur.
 107     vtable_length = Universe::base_vtable_size();
 108   }
 109   assert(super != NULL || vtable_length == Universe::base_vtable_size(),
 110          "bad vtable size for class Object");
 111   assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
 112   assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
 113 }
 114 
 115 int klassVtable::index_of(methodOop m, int len) const {
 116   assert(m->vtable_index() >= 0, "do not ask this of non-vtable methods");
 117   return m->vtable_index();
 118 }
 119 
 120 int klassVtable::initialize_from_super(KlassHandle super) {
 121   if (super.is_null()) {
 122     return 0;
 123   } else {
 124     // copy methods from superKlass
 125     // can't inherit from array class, so must be instanceKlass
 126     assert(super->oop_is_instance(), "must be instance klass");
 127     instanceKlass* sk = (instanceKlass*)super()->klass_part();
 128     klassVtable* superVtable = sk->vtable();
 129     assert(superVtable->length() <= _length, "vtable too short");
 130 #ifdef ASSERT
 131     superVtable->verify(tty, true);
 132 #endif
 133     superVtable->copy_vtable_to(table());
 134 #ifndef PRODUCT
 135     if (PrintVtables && Verbose) {
 136       ResourceMark rm;
 137       tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length);
 138     }
 139 #endif
 140     return superVtable->length();
 141   }
 142 }
 143 
 144 // Revised lookup semantics   introduced 1.3 (Kestral beta)
 145 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
 146 
 147   // Note:  Arrays can have intermediate array supers.  Use java_super to skip them.
 148   KlassHandle super (THREAD, klass()->java_super());
 149   int nofNewEntries = 0;
 150 
 151 
 152   if (PrintVtables && !klass()->oop_is_array()) {
 153     ResourceMark rm(THREAD);
 154     tty->print_cr("Initializing: %s", _klass->name()->as_C_string());
 155   }
 156 
 157 #ifdef ASSERT
 158   oop* end_of_obj = (oop*)_klass() + _klass()->size();
 159   oop* end_of_vtable = (oop*)&table()[_length];
 160   assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
 161 #endif
 162 
 163   if (Universe::is_bootstrapping()) {
 164     // just clear everything
 165     for (int i = 0; i < _length; i++) table()[i].clear();
 166     return;
 167   }
 168 
 169   int super_vtable_len = initialize_from_super(super);
 170   if (klass()->oop_is_array()) {
 171     assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
 172   } else {
 173     assert(_klass->oop_is_instance(), "must be instanceKlass");
 174 
 175     objArrayHandle methods(THREAD, ik()->methods());
 176     int len = methods()->length();
 177     int initialized = super_vtable_len;
 178 
 179     // update_inherited_vtable can stop for gc - ensure using handles
 180     for (int i = 0; i < len; i++) {
 181       HandleMark hm(THREAD);
 182       assert(methods()->obj_at(i)->is_method(), "must be a methodOop");
 183       methodHandle mh(THREAD, (methodOop)methods()->obj_at(i));
 184 
 185       bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, checkconstraints, CHECK);
 186 
 187       if (needs_new_entry) {
 188         put_method_at(mh(), initialized);
 189         mh()->set_vtable_index(initialized); // set primary vtable index
 190         initialized++;
 191       }
 192     }
 193 
 194     // add miranda methods; it will also update the value of initialized
 195     fill_in_mirandas(initialized);
 196 
 197     // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
 198     // package_private -> publicprotected), the vtable might actually be smaller than our initial
 199     // calculation.
 200     assert(initialized <= _length, "vtable initialization failed");
 201     for(;initialized < _length; initialized++) {
 202       put_method_at(NULL, initialized);
 203     }
 204     NOT_PRODUCT(verify(tty, true));
 205   }
 206 }
 207 
 208 // Called for cases where a method does not override its superclass' vtable entry
 209 // For bytecodes not produced by javac together it is possible that a method does not override
 210 // the superclass's method, but might indirectly override a super-super class's vtable entry
 211 // If none found, return a null superk, else return the superk of the method this does override
 212 instanceKlass* klassVtable::find_transitive_override(instanceKlass* initialsuper, methodHandle target_method,
 213                             int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
 214   instanceKlass* superk = initialsuper;
 215   while (superk != NULL && superk->super() != NULL) {
 216     instanceKlass* supersuperklass = instanceKlass::cast(superk->super());
 217     klassVtable* ssVtable = supersuperklass->vtable();
 218     if (vtable_index < ssVtable->length()) {
 219       methodOop super_method = ssVtable->method_at(vtable_index);
 220 #ifndef PRODUCT
 221       Symbol* name= target_method()->name();
 222       Symbol* signature = target_method()->signature();
 223       assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
 224 #endif
 225       if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
 226 #ifndef PRODUCT
 227         if (PrintVtables && Verbose) {
 228           ResourceMark rm(THREAD);
 229           tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
 230            supersuperklass->internal_name(),
 231            _klass->internal_name(), (target_method() != NULL) ?
 232            target_method()->name()->as_C_string() : "<NULL>", vtable_index);
 233            super_method->access_flags().print_on(tty);
 234            tty->print("overriders flags: ");
 235            target_method->access_flags().print_on(tty);
 236            tty->cr();
 237         }
 238 #endif /*PRODUCT*/
 239         break; // return found superk
 240       }
 241     } else  {
 242       // super class has no vtable entry here, stop transitive search
 243       superk = (instanceKlass*)NULL;
 244       break;
 245     }
 246     // if no override found yet, continue to search up
 247     superk = instanceKlass::cast(superk->super());
 248   }
 249 
 250   return superk;
 251 }
 252 
 253 
 254 // Update child's copy of super vtable for overrides
 255 // OR return true if a new vtable entry is required
 256 // Only called for instanceKlass's, i.e. not for arrays
 257 // If that changed, could not use _klass as handle for klass
 258 bool klassVtable::update_inherited_vtable(instanceKlass* klass, methodHandle target_method, int super_vtable_len,
 259                   bool checkconstraints, TRAPS) {
 260   ResourceMark rm;
 261   bool allocate_new = true;
 262   assert(klass->oop_is_instance(), "must be instanceKlass");
 263 
 264   // Initialize the method's vtable index to "nonvirtual".
 265   // If we allocate a vtable entry, we will update it to a non-negative number.
 266   target_method()->set_vtable_index(methodOopDesc::nonvirtual_vtable_index);
 267 
 268   // Static and <init> methods are never in
 269   if (target_method()->is_static() || target_method()->name() ==  vmSymbols::object_initializer_name()) {
 270     return false;
 271   }
 272 
 273   if (klass->is_final() || target_method()->is_final()) {
 274     // a final method never needs a new entry; final methods can be statically
 275     // resolved and they have to be present in the vtable only if they override
 276     // a super's method, in which case they re-use its entry
 277     allocate_new = false;
 278   }
 279 
 280   // we need a new entry if there is no superclass
 281   if (klass->super() == NULL) {
 282     return allocate_new;
 283   }
 284 
 285   // private methods always have a new entry in the vtable
 286   // specification interpretation since classic has
 287   // private methods not overriding
 288   if (target_method()->is_private()) {
 289     return allocate_new;
 290   }
 291 
 292   // search through the vtable and update overridden entries
 293   // Since check_signature_loaders acquires SystemDictionary_lock
 294   // which can block for gc, once we are in this loop, use handles
 295   // For classfiles built with >= jdk7, we now look for transitive overrides
 296 
 297   Symbol* name = target_method()->name();
 298   Symbol* signature = target_method()->signature();
 299   Handle target_loader(THREAD, _klass->class_loader());
 300   Symbol*  target_classname = _klass->name();
 301   for(int i = 0; i < super_vtable_len; i++) {
 302     methodOop super_method = method_at(i);
 303     // Check if method name matches
 304     if (super_method->name() == name && super_method->signature() == signature) {
 305 
 306       // get super_klass for method_holder for the found method
 307       instanceKlass* super_klass =  instanceKlass::cast(super_method->method_holder());
 308 
 309       if ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) ||
 310       ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
 311         && ((super_klass = find_transitive_override(super_klass, target_method, i, target_loader,
 312              target_classname, THREAD)) != (instanceKlass*)NULL))) {
 313         // overriding, so no new entry
 314         allocate_new = false;
 315 
 316         if (checkconstraints) {
 317         // Override vtable entry if passes loader constraint check
 318         // if loader constraint checking requested
 319         // No need to visit his super, since he and his super
 320         // have already made any needed loader constraints.
 321         // Since loader constraints are transitive, it is enough
 322         // to link to the first super, and we get all the others.
 323           Handle super_loader(THREAD, super_klass->class_loader());
 324 
 325           if (target_loader() != super_loader()) {
 326             ResourceMark rm(THREAD);
 327             char* failed_type_name =
 328               SystemDictionary::check_signature_loaders(signature, target_loader,
 329                                                         super_loader, true,
 330                                                         CHECK_(false));
 331             if (failed_type_name != NULL) {
 332               const char* msg = "loader constraint violation: when resolving "
 333                 "overridden method \"%s\" the class loader (instance"
 334                 " of %s) of the current class, %s, and its superclass loader "
 335                 "(instance of %s), have different Class objects for the type "
 336                 "%s used in the signature";
 337               char* sig = target_method()->name_and_sig_as_C_string();
 338               const char* loader1 = SystemDictionary::loader_name(target_loader());
 339               char* current = _klass->name()->as_C_string();
 340               const char* loader2 = SystemDictionary::loader_name(super_loader());
 341               size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
 342                 strlen(current) + strlen(loader2) + strlen(failed_type_name);
 343               char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
 344               jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
 345                            failed_type_name);
 346               THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
 347             }
 348           }
 349        }
 350 
 351         put_method_at(target_method(), i);
 352         target_method()->set_vtable_index(i);
 353 #ifndef PRODUCT
 354         if (PrintVtables && Verbose) {
 355           tty->print("overriding with %s::%s index %d, original flags: ",
 356            _klass->internal_name(), (target_method() != NULL) ?
 357            target_method()->name()->as_C_string() : "<NULL>", i);
 358            super_method->access_flags().print_on(tty);
 359            tty->print("overriders flags: ");
 360            target_method->access_flags().print_on(tty);
 361            tty->cr();
 362         }
 363 #endif /*PRODUCT*/
 364       } else {
 365         // allocate_new = true; default. We might override one entry,
 366         // but not override another. Once we override one, not need new
 367 #ifndef PRODUCT
 368         if (PrintVtables && Verbose) {
 369           tty->print("NOT overriding with %s::%s index %d, original flags: ",
 370            _klass->internal_name(), (target_method() != NULL) ?
 371            target_method()->name()->as_C_string() : "<NULL>", i);
 372            super_method->access_flags().print_on(tty);
 373            tty->print("overriders flags: ");
 374            target_method->access_flags().print_on(tty);
 375            tty->cr();
 376         }
 377 #endif /*PRODUCT*/
 378       }
 379     }
 380   }
 381   return allocate_new;
 382 }
 383 
 384 void klassVtable::put_method_at(methodOop m, int index) {
 385   assert(m->is_oop_or_null(), "Not an oop or null");
 386 #ifndef PRODUCT
 387   if (PrintVtables && Verbose) {
 388     ResourceMark rm;
 389     tty->print_cr("adding %s::%s at index %d", _klass->internal_name(),
 390       (m != NULL) ? m->name()->as_C_string() : "<NULL>", index);
 391   }
 392   assert(unchecked_method_at(index)->is_oop_or_null(), "Not an oop or null");
 393 #endif
 394   table()[index].set(m);
 395 }
 396 
 397 // Find out if a method "m" with superclass "super", loader "classloader" and
 398 // name "classname" needs a new vtable entry.  Let P be a class package defined
 399 // by "classloader" and "classname".
 400 // NOTE: The logic used here is very similar to the one used for computing
 401 // the vtables indices for a method. We cannot directly use that function because,
 402 // we allocate the instanceKlass at load time, and that requires that the
 403 // superclass has been loaded.
 404 // However, the vtable entries are filled in at link time, and therefore
 405 // the superclass' vtable may not yet have been filled in.
 406 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
 407                                          klassOop super,
 408                                          Handle classloader,
 409                                          Symbol* classname,
 410                                          AccessFlags class_flags,
 411                                          TRAPS) {
 412   if ((class_flags.is_final() || target_method()->is_final()) ||
 413       // a final method never needs a new entry; final methods can be statically
 414       // resolved and they have to be present in the vtable only if they override
 415       // a super's method, in which case they re-use its entry
 416       (target_method()->is_static()) ||
 417       // static methods don't need to be in vtable
 418       (target_method()->name() ==  vmSymbols::object_initializer_name())
 419       // <init> is never called dynamically-bound
 420       ) {
 421     return false;
 422   }
 423 
 424   // we need a new entry if there is no superclass
 425   if (super == NULL) {
 426     return true;
 427   }
 428 
 429   // private methods always have a new entry in the vtable
 430   // specification interpretation since classic has
 431   // private methods not overriding
 432   if (target_method()->is_private()) {
 433     return true;
 434   }
 435 
 436   // search through the super class hierarchy to see if we need
 437   // a new entry
 438   ResourceMark rm;
 439   Symbol* name = target_method()->name();
 440   Symbol* signature = target_method()->signature();
 441   klassOop k = super;
 442   methodOop super_method = NULL;
 443   instanceKlass *holder = NULL;
 444   methodOop recheck_method =  NULL;
 445   while (k != NULL) {
 446     // lookup through the hierarchy for a method with matching name and sign.
 447     super_method = instanceKlass::cast(k)->lookup_method(name, signature);
 448     if (super_method == NULL) {
 449       break; // we still have to search for a matching miranda method
 450     }
 451     // get the class holding the matching method
 452     // make sure you use that class for is_override
 453     instanceKlass* superk = instanceKlass::cast(super_method->method_holder());
 454     // we want only instance method matches
 455     // pretend private methods are not in the super vtable
 456     // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
 457     // ignore private, c.m pub does override a.m pub
 458     // For classes that were not javac'd together, we also do transitive overriding around
 459     // methods that have less accessibility
 460     if ((!super_method->is_static()) &&
 461        (!super_method->is_private())) {
 462       if (superk->is_override(super_method, classloader, classname, THREAD)) {
 463         return false;
 464       // else keep looking for transitive overrides
 465       }
 466     }
 467 
 468     // Start with lookup result and continue to search up
 469     k = superk->super(); // haven't found an override match yet; continue to look
 470   }
 471 
 472   // if the target method is public or protected it may have a matching
 473   // miranda method in the super, whose entry it should re-use.
 474   // Actually, to handle cases that javac would not generate, we need
 475   // this check for all access permissions.
 476   instanceKlass *sk = instanceKlass::cast(super);
 477   if (sk->has_miranda_methods()) {
 478     if (sk->lookup_method_in_all_interfaces(name, signature) != NULL) {
 479       return false;  // found a matching miranda; we do not need a new entry
 480     }
 481   }
 482   return true; // found no match; we need a new entry
 483 }
 484 
 485 // Support for miranda methods
 486 
 487 // get the vtable index of a miranda method with matching "name" and "signature"
 488 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
 489   // search from the bottom, might be faster
 490   for (int i = (length() - 1); i >= 0; i--) {
 491     methodOop m = table()[i].method();
 492     if (is_miranda_entry_at(i) &&
 493         m->name() == name && m->signature() == signature) {
 494       return i;
 495     }
 496   }
 497   return methodOopDesc::invalid_vtable_index;
 498 }
 499 
 500 // check if an entry is miranda
 501 bool klassVtable::is_miranda_entry_at(int i) {
 502   methodOop m = method_at(i);
 503   klassOop method_holder = m->method_holder();
 504   instanceKlass *mhk = instanceKlass::cast(method_holder);
 505 
 506   // miranda methods are interface methods in a class's vtable
 507   if (mhk->is_interface()) {
 508     assert(m->is_public() && m->is_abstract(), "should be public and abstract");
 509     assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
 510     assert(is_miranda(m, ik()->methods(), ik()->super()), "should be a miranda_method");
 511     return true;
 512   }
 513   return false;
 514 }
 515 
 516 // check if a method is a miranda method, given a class's methods table and it's super
 517 // the caller must make sure that the method belongs to an interface implemented by the class
 518 bool klassVtable::is_miranda(methodOop m, objArrayOop class_methods, klassOop super) {
 519   Symbol* name = m->name();
 520   Symbol* signature = m->signature();
 521   if (instanceKlass::find_method(class_methods, name, signature) == NULL) {
 522     // did not find it in the method table of the current class
 523     if (super == NULL) {
 524       // super doesn't exist
 525       return true;
 526     }
 527 
 528     methodOop mo = instanceKlass::cast(super)->lookup_method(name, signature);
 529     if (mo == NULL || mo->access_flags().is_private() ) {
 530       // super class hierarchy does not implement it or protection is different
 531       return true;
 532     }
 533   }
 534 
 535   return false;
 536 }
 537 
 538 void klassVtable::add_new_mirandas_to_list(GrowableArray<methodOop>* list_of_current_mirandas,
 539                                            objArrayOop current_interface_methods,
 540                                            objArrayOop class_methods,
 541                                            klassOop super) {
 542   // iterate thru the current interface's method to see if it a miranda
 543   int num_methods = current_interface_methods->length();
 544   for (int i = 0; i < num_methods; i++) {
 545     methodOop im = methodOop(current_interface_methods->obj_at(i));
 546     bool is_duplicate = false;
 547     int num_of_current_mirandas = list_of_current_mirandas->length();
 548     // check for duplicate mirandas in different interfaces we implement
 549     for (int j = 0; j < num_of_current_mirandas; j++) {
 550       methodOop miranda = list_of_current_mirandas->at(j);
 551       if ((im->name() == miranda->name()) &&
 552           (im->signature() == miranda->signature())) {
 553         is_duplicate = true;
 554         break;
 555       }
 556     }
 557 
 558     if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
 559       if (is_miranda(im, class_methods, super)) { // is it a miranda at all?
 560         instanceKlass *sk = instanceKlass::cast(super);
 561         // check if it is a duplicate of a super's miranda
 562         if (sk->lookup_method_in_all_interfaces(im->name(), im->signature()) == NULL) {
 563           list_of_current_mirandas->append(im);
 564         }
 565       }
 566     }
 567   }
 568 }
 569 
 570 void klassVtable::get_mirandas(GrowableArray<methodOop>* mirandas,
 571                                klassOop super, objArrayOop class_methods,
 572                                objArrayOop local_interfaces) {
 573   assert((mirandas->length() == 0) , "current mirandas must be 0");
 574 
 575   // iterate thru the local interfaces looking for a miranda
 576   int num_local_ifs = local_interfaces->length();
 577   for (int i = 0; i < num_local_ifs; i++) {
 578     instanceKlass *ik = instanceKlass::cast(klassOop(local_interfaces->obj_at(i)));
 579     add_new_mirandas_to_list(mirandas, ik->methods(), class_methods, super);
 580     // iterate thru each local's super interfaces
 581     objArrayOop super_ifs = ik->transitive_interfaces();
 582     int num_super_ifs = super_ifs->length();
 583     for (int j = 0; j < num_super_ifs; j++) {
 584       instanceKlass *sik = instanceKlass::cast(klassOop(super_ifs->obj_at(j)));
 585       add_new_mirandas_to_list(mirandas, sik->methods(), class_methods, super);
 586     }
 587   }
 588 }
 589 
 590 // get number of mirandas
 591 int klassVtable::get_num_mirandas(klassOop super, objArrayOop class_methods, objArrayOop local_interfaces) {
 592   ResourceMark rm;
 593   GrowableArray<methodOop>* mirandas = new GrowableArray<methodOop>(20);
 594   get_mirandas(mirandas, super, class_methods, local_interfaces);
 595   return mirandas->length();
 596 }
 597 
 598 // fill in mirandas
 599 void klassVtable::fill_in_mirandas(int& initialized) {
 600   ResourceMark rm;
 601   GrowableArray<methodOop>* mirandas = new GrowableArray<methodOop>(20);
 602   instanceKlass *this_ik = ik();
 603   get_mirandas(mirandas, this_ik->super(), this_ik->methods(), this_ik->local_interfaces());
 604   int num_mirandas = mirandas->length();
 605   for (int i = 0; i < num_mirandas; i++) {
 606     put_method_at(mirandas->at(i), initialized);
 607     initialized++;
 608   }
 609 }
 610 
 611 void klassVtable::copy_vtable_to(vtableEntry* start) {
 612   Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
 613 }
 614 
 615 void klassVtable::adjust_method_entries(methodOop* old_methods, methodOop* new_methods,
 616                                         int methods_length, bool * trace_name_printed) {
 617   // search the vtable for uses of either obsolete or EMCP methods
 618   for (int j = 0; j < methods_length; j++) {
 619     methodOop old_method = old_methods[j];
 620     methodOop new_method = new_methods[j];
 621 
 622     // In the vast majority of cases we could get the vtable index
 623     // by using:  old_method->vtable_index()
 624     // However, there are rare cases, eg. sun.awt.X11.XDecoratedPeer.getX()
 625     // in sun.awt.X11.XFramePeer where methods occur more than once in the
 626     // vtable, so, alas, we must do an exhaustive search.
 627     for (int index = 0; index < length(); index++) {
 628       if (unchecked_method_at(index) == old_method) {
 629         put_method_at(new_method, index);
 630 
 631         if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
 632           if (!(*trace_name_printed)) {
 633             // RC_TRACE_MESG macro has an embedded ResourceMark
 634             RC_TRACE_MESG(("adjust: name=%s",
 635                            Klass::cast(old_method->method_holder())->external_name()));
 636             *trace_name_printed = true;
 637           }
 638           // RC_TRACE macro has an embedded ResourceMark
 639           RC_TRACE(0x00100000, ("vtable method update: %s(%s)",
 640                                 new_method->name()->as_C_string(),
 641                                 new_method->signature()->as_C_string()));
 642         }
 643       }
 644     }
 645   }
 646 }
 647 
 648 // a vtable should never contain old or obsolete methods
 649 bool klassVtable::check_no_old_or_obsolete_entries() {
 650   for (int i = 0; i < length(); i++) {
 651     methodOop m = unchecked_method_at(i);
 652     if (m != NULL && (m->is_old() || m->is_obsolete())) {
 653       return false;
 654     }
 655   }
 656   return true;
 657 }
 658 
 659 void klassVtable::dump_vtable() {
 660   // adds a searchable prefix when RedefineClasses() tracing is enabled
 661   RC_TRACE_NO_CR(0x00004000, (""));
 662   tty->print_cr("vtable dump --");
 663   for (int i = 0; i < length(); i++) {
 664     methodOop m = unchecked_method_at(i);
 665     if (m != NULL) {
 666       RC_TRACE_NO_CR(0x00004000, (""));
 667       tty->print("      (%5d)  ", i);
 668       m->access_flags().print_on(tty);
 669       tty->print(" --  ");
 670       m->print_name(tty);
 671       tty->cr();
 672     }
 673   }
 674 }
 675 
 676 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
 677 void klassVtable::clear_vtable() {
 678   for (int i = 0; i < _length; i++) table()[i].clear();
 679 }
 680 
 681 bool klassVtable::is_initialized() {
 682   return _length == 0 || table()[0].method() != NULL;
 683 }
 684 
 685 
 686 // Garbage collection
 687 void klassVtable::oop_follow_contents() {
 688   int len = length();
 689   for (int i = 0; i < len; i++) {
 690     MarkSweep::mark_and_push(adr_method_at(i));
 691   }
 692 }
 693 
 694 #ifndef SERIALGC
 695 void klassVtable::oop_follow_contents(ParCompactionManager* cm) {
 696   int len = length();
 697   for (int i = 0; i < len; i++) {
 698     PSParallelCompact::mark_and_push(cm, adr_method_at(i));
 699   }
 700 }
 701 #endif // SERIALGC
 702 
 703 void klassVtable::oop_adjust_pointers() {
 704   int len = length();
 705   for (int i = 0; i < len; i++) {
 706     MarkSweep::adjust_pointer(adr_method_at(i));
 707   }
 708 }
 709 
 710 #ifndef SERIALGC
 711 void klassVtable::oop_update_pointers(ParCompactionManager* cm) {
 712   const int n = length();
 713   for (int i = 0; i < n; i++) {
 714     PSParallelCompact::adjust_pointer(adr_method_at(i));
 715   }
 716 }
 717 #endif // SERIALGC
 718 
 719 // Iterators
 720 void klassVtable::oop_oop_iterate(OopClosure* blk) {
 721   int len = length();
 722   for (int i = 0; i < len; i++) {
 723     blk->do_oop(adr_method_at(i));
 724   }
 725 }
 726 
 727 void klassVtable::oop_oop_iterate_m(OopClosure* blk, MemRegion mr) {
 728   int len = length();
 729   int i;
 730   for (i = 0; i < len; i++) {
 731     if ((HeapWord*)adr_method_at(i) >= mr.start()) break;
 732   }
 733   for (; i < len; i++) {
 734     oop* adr = adr_method_at(i);
 735     if ((HeapWord*)adr < mr.end()) blk->do_oop(adr);
 736   }
 737 }
 738 
 739 //-----------------------------------------------------------------------------------------
 740 // Itable code
 741 
 742 // Initialize a itableMethodEntry
 743 void itableMethodEntry::initialize(methodOop m) {
 744   if (m == NULL) return;
 745 
 746   _method = m;
 747 }
 748 
 749 klassItable::klassItable(instanceKlassHandle klass) {
 750   _klass = klass;
 751 
 752   if (klass->itable_length() > 0) {
 753     itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
 754     if (offset_entry  != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
 755       // First offset entry points to the first method_entry
 756       intptr_t* method_entry  = (intptr_t *)(((address)klass->as_klassOop()) + offset_entry->offset());
 757       intptr_t* end         = klass->end_of_itable();
 758 
 759       _table_offset      = (intptr_t*)offset_entry - (intptr_t*)klass->as_klassOop();
 760       _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
 761       _size_method_table = (end - method_entry)                  / itableMethodEntry::size();
 762       assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
 763       return;
 764     }
 765   }
 766 
 767   // The length of the itable was either zero, or it has not yet been initialized.
 768   _table_offset      = 0;
 769   _size_offset_table = 0;
 770   _size_method_table = 0;
 771 }
 772 
 773 // Garbage Collection
 774 
 775 void klassItable::oop_follow_contents() {
 776   // offset table
 777   itableOffsetEntry* ioe = offset_entry(0);
 778   for(int i = 0; i < _size_offset_table; i++) {
 779     MarkSweep::mark_and_push((oop*)&ioe->_interface);
 780     ioe++;
 781   }
 782 
 783   // method table
 784   itableMethodEntry* ime = method_entry(0);
 785   for(int j = 0; j < _size_method_table; j++) {
 786     MarkSweep::mark_and_push((oop*)&ime->_method);
 787     ime++;
 788   }
 789 }
 790 
 791 #ifndef SERIALGC
 792 void klassItable::oop_follow_contents(ParCompactionManager* cm) {
 793   // offset table
 794   itableOffsetEntry* ioe = offset_entry(0);
 795   for(int i = 0; i < _size_offset_table; i++) {
 796     PSParallelCompact::mark_and_push(cm, (oop*)&ioe->_interface);
 797     ioe++;
 798   }
 799 
 800   // method table
 801   itableMethodEntry* ime = method_entry(0);
 802   for(int j = 0; j < _size_method_table; j++) {
 803     PSParallelCompact::mark_and_push(cm, (oop*)&ime->_method);
 804     ime++;
 805   }
 806 }
 807 #endif // SERIALGC
 808 
 809 void klassItable::oop_adjust_pointers() {
 810   // offset table
 811   itableOffsetEntry* ioe = offset_entry(0);
 812   for(int i = 0; i < _size_offset_table; i++) {
 813     MarkSweep::adjust_pointer((oop*)&ioe->_interface);
 814     ioe++;
 815   }
 816 
 817   // method table
 818   itableMethodEntry* ime = method_entry(0);
 819   for(int j = 0; j < _size_method_table; j++) {
 820     MarkSweep::adjust_pointer((oop*)&ime->_method);
 821     ime++;
 822   }
 823 }
 824 
 825 #ifndef SERIALGC
 826 void klassItable::oop_update_pointers(ParCompactionManager* cm) {
 827   // offset table
 828   itableOffsetEntry* ioe = offset_entry(0);
 829   for(int i = 0; i < _size_offset_table; i++) {
 830     PSParallelCompact::adjust_pointer((oop*)&ioe->_interface);
 831     ioe++;
 832   }
 833 
 834   // method table
 835   itableMethodEntry* ime = method_entry(0);
 836   for(int j = 0; j < _size_method_table; j++) {
 837     PSParallelCompact::adjust_pointer((oop*)&ime->_method);
 838     ime++;
 839   }
 840 }
 841 #endif // SERIALGC
 842 
 843 // Iterators
 844 void klassItable::oop_oop_iterate(OopClosure* blk) {
 845   // offset table
 846   itableOffsetEntry* ioe = offset_entry(0);
 847   for(int i = 0; i < _size_offset_table; i++) {
 848     blk->do_oop((oop*)&ioe->_interface);
 849     ioe++;
 850   }
 851 
 852   // method table
 853   itableMethodEntry* ime = method_entry(0);
 854   for(int j = 0; j < _size_method_table; j++) {
 855     blk->do_oop((oop*)&ime->_method);
 856     ime++;
 857   }
 858 }
 859 
 860 void klassItable::oop_oop_iterate_m(OopClosure* blk, MemRegion mr) {
 861   // offset table
 862   itableOffsetEntry* ioe = offset_entry(0);
 863   for(int i = 0; i < _size_offset_table; i++) {
 864     oop* adr = (oop*)&ioe->_interface;
 865     if (mr.contains(adr)) blk->do_oop(adr);
 866     ioe++;
 867   }
 868 
 869   // method table
 870   itableMethodEntry* ime = method_entry(0);
 871   for(int j = 0; j < _size_method_table; j++) {
 872     oop* adr = (oop*)&ime->_method;
 873     if (mr.contains(adr)) blk->do_oop(adr);
 874     ime++;
 875   }
 876 }
 877 
 878 
 879 static int initialize_count = 0;
 880 
 881 // Initialization
 882 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
 883   // Cannot be setup doing bootstrapping, interfaces don't have
 884   // itables, and klass with only ones entry have empty itables
 885   if (Universe::is_bootstrapping() ||
 886       _klass->is_interface() ||
 887       _klass->itable_length() == itableOffsetEntry::size()) return;
 888 
 889   // There's alway an extra itable entry so we can null-terminate it.
 890   guarantee(size_offset_table() >= 1, "too small");
 891   int num_interfaces = size_offset_table() - 1;
 892   if (num_interfaces > 0) {
 893     if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count,
 894                                     _klass->name()->as_C_string());
 895 
 896 
 897     // Iterate through all interfaces
 898     int i;
 899     for(i = 0; i < num_interfaces; i++) {
 900       itableOffsetEntry* ioe = offset_entry(i);
 901       KlassHandle interf_h (THREAD, ioe->interface_klass());
 902       assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
 903       initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
 904     }
 905 
 906   }
 907   // Check that the last entry is empty
 908   itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
 909   guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
 910 }
 911 
 912 
 913 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
 914   objArrayHandle methods(THREAD, instanceKlass::cast(interf_h())->methods());
 915   int nof_methods = methods()->length();
 916   HandleMark hm;
 917   KlassHandle klass = _klass;
 918   assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
 919   Handle interface_loader (THREAD, instanceKlass::cast(interf_h())->class_loader());
 920   int ime_num = 0;
 921 
 922   // Skip first methodOop if it is a class initializer
 923   int i = ((methodOop)methods()->obj_at(0))->is_static_initializer() ? 1 : 0;
 924 
 925   // m, method_name, method_signature, klass reset each loop so they
 926   // don't need preserving across check_signature_loaders call
 927   // methods needs a handle in case of gc from check_signature_loaders
 928   for(; i < nof_methods; i++) {
 929     methodOop m = (methodOop)methods()->obj_at(i);
 930     Symbol* method_name = m->name();
 931     Symbol* method_signature = m->signature();
 932 
 933     // This is same code as in Linkresolver::lookup_instance_method_in_klasses
 934     methodOop target = klass->uncached_lookup_method(method_name, method_signature);
 935     while (target != NULL && target->is_static()) {
 936       // continue with recursive lookup through the superclass
 937       klassOop super = Klass::cast(target->method_holder())->super();
 938       target = (super == NULL) ? methodOop(NULL) : Klass::cast(super)->uncached_lookup_method(method_name, method_signature);
 939     }
 940     if (target == NULL || !target->is_public() || target->is_abstract()) {
 941       // Entry do not resolve. Leave it empty
 942     } else {
 943       // Entry did resolve, check loader constraints before initializing
 944       // if checkconstraints requested
 945       methodHandle  target_h (THREAD, target); // preserve across gc
 946       if (checkconstraints) {
 947         Handle method_holder_loader (THREAD, instanceKlass::cast(target->method_holder())->class_loader());
 948         if (method_holder_loader() != interface_loader()) {
 949           ResourceMark rm(THREAD);
 950           char* failed_type_name =
 951             SystemDictionary::check_signature_loaders(method_signature,
 952                                                       method_holder_loader,
 953                                                       interface_loader,
 954                                                       true, CHECK);
 955           if (failed_type_name != NULL) {
 956             const char* msg = "loader constraint violation in interface "
 957               "itable initialization: when resolving method \"%s\" the class"
 958               " loader (instance of %s) of the current class, %s, "
 959               "and the class loader (instance of %s) for interface "
 960               "%s have different Class objects for the type %s "
 961               "used in the signature";
 962             char* sig = target_h()->name_and_sig_as_C_string();
 963             const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
 964             char* current = klass->name()->as_C_string();
 965             const char* loader2 = SystemDictionary::loader_name(interface_loader());
 966             char* iface = instanceKlass::cast(interf_h())->name()->as_C_string();
 967             size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
 968               strlen(current) + strlen(loader2) + strlen(iface) +
 969               strlen(failed_type_name);
 970             char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
 971             jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
 972                          iface, failed_type_name);
 973             THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
 974           }
 975         }
 976       }
 977 
 978       // ime may have moved during GC so recalculate address
 979       itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target_h());
 980     }
 981     // Progress to next entry
 982     ime_num++;
 983   }
 984 }
 985 
 986 // Update entry for specific methodOop
 987 void klassItable::initialize_with_method(methodOop m) {
 988   itableMethodEntry* ime = method_entry(0);
 989   for(int i = 0; i < _size_method_table; i++) {
 990     if (ime->method() == m) {
 991       ime->initialize(m);
 992     }
 993     ime++;
 994   }
 995 }
 996 
 997 void klassItable::adjust_method_entries(methodOop* old_methods, methodOop* new_methods,
 998                                         int methods_length, bool * trace_name_printed) {
 999   // search the itable for uses of either obsolete or EMCP methods
1000   for (int j = 0; j < methods_length; j++) {
1001     methodOop old_method = old_methods[j];
1002     methodOop new_method = new_methods[j];
1003     itableMethodEntry* ime = method_entry(0);
1004 
1005     // The itable can describe more than one interface and the same
1006     // method signature can be specified by more than one interface.
1007     // This means we have to do an exhaustive search to find all the
1008     // old_method references.
1009     for (int i = 0; i < _size_method_table; i++) {
1010       if (ime->method() == old_method) {
1011         ime->initialize(new_method);
1012 
1013         if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
1014           if (!(*trace_name_printed)) {
1015             // RC_TRACE_MESG macro has an embedded ResourceMark
1016             RC_TRACE_MESG(("adjust: name=%s",
1017               Klass::cast(old_method->method_holder())->external_name()));
1018             *trace_name_printed = true;
1019           }
1020           // RC_TRACE macro has an embedded ResourceMark
1021           RC_TRACE(0x00200000, ("itable method update: %s(%s)",
1022             new_method->name()->as_C_string(),
1023             new_method->signature()->as_C_string()));
1024         }
1025         // cannot 'break' here; see for-loop comment above.
1026       }
1027       ime++;
1028     }
1029   }
1030 }
1031 
1032 // an itable should never contain old or obsolete methods
1033 bool klassItable::check_no_old_or_obsolete_entries() {
1034   itableMethodEntry* ime = method_entry(0);
1035   for (int i = 0; i < _size_method_table; i++) {
1036     methodOop m = ime->method();
1037     if (m != NULL && (m->is_old() || m->is_obsolete())) {
1038       return false;
1039     }
1040     ime++;
1041   }
1042   return true;
1043 }
1044 
1045 void klassItable::dump_itable() {
1046   itableMethodEntry* ime = method_entry(0);
1047   // adds a searchable prefix when RedefineClasses() tracing is enabled
1048   RC_TRACE_NO_CR(0x00004000, (""));
1049   tty->print_cr("itable dump --");
1050   for (int i = 0; i < _size_method_table; i++) {
1051     methodOop m = ime->method();
1052     if (m != NULL) {
1053       RC_TRACE_NO_CR(0x00004000, (""));
1054       tty->print("      (%5d)  ", i);
1055       m->access_flags().print_on(tty);
1056       tty->print(" --  ");
1057       m->print_name(tty);
1058       tty->cr();
1059     }
1060     ime++;
1061   }
1062 }
1063 
1064 
1065 // Setup
1066 class InterfaceVisiterClosure : public StackObj {
1067  public:
1068   virtual void doit(klassOop intf, int method_count) = 0;
1069 };
1070 
1071 // Visit all interfaces with at-least one method (excluding <clinit>)
1072 void visit_all_interfaces(objArrayOop transitive_intf, InterfaceVisiterClosure *blk) {
1073   // Handle array argument
1074   for(int i = 0; i < transitive_intf->length(); i++) {
1075     klassOop intf = (klassOop)transitive_intf->obj_at(i);
1076     assert(Klass::cast(intf)->is_interface(), "sanity check");
1077 
1078     // Find no. of methods excluding a <clinit>
1079     int method_count = instanceKlass::cast(intf)->methods()->length();
1080     if (method_count > 0) {
1081       methodOop m = (methodOop)instanceKlass::cast(intf)->methods()->obj_at(0);
1082       assert(m != NULL && m->is_method(), "sanity check");
1083       if (m->name() == vmSymbols::object_initializer_name()) {
1084         method_count--;
1085       }
1086     }
1087 
1088     // Only count interfaces with at least one method
1089     if (method_count > 0) {
1090       blk->doit(intf, method_count);
1091     }
1092   }
1093 }
1094 
1095 class CountInterfacesClosure : public InterfaceVisiterClosure {
1096  private:
1097   int _nof_methods;
1098   int _nof_interfaces;
1099  public:
1100    CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1101 
1102    int nof_methods() const    { return _nof_methods; }
1103    int nof_interfaces() const { return _nof_interfaces; }
1104 
1105    void doit(klassOop intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1106 };
1107 
1108 class SetupItableClosure : public InterfaceVisiterClosure  {
1109  private:
1110   itableOffsetEntry* _offset_entry;
1111   itableMethodEntry* _method_entry;
1112   address            _klass_begin;
1113  public:
1114   SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1115     _klass_begin  = klass_begin;
1116     _offset_entry = offset_entry;
1117     _method_entry = method_entry;
1118   }
1119 
1120   itableMethodEntry* method_entry() const { return _method_entry; }
1121 
1122   void doit(klassOop intf, int method_count) {
1123     int offset = ((address)_method_entry) - _klass_begin;
1124     _offset_entry->initialize(intf, offset);
1125     _offset_entry++;
1126     _method_entry += method_count;
1127   }
1128 };
1129 
1130 int klassItable::compute_itable_size(objArrayHandle transitive_interfaces) {
1131   // Count no of interfaces and total number of interface methods
1132   CountInterfacesClosure cic;
1133   visit_all_interfaces(transitive_interfaces(), &cic);
1134 
1135   // There's alway an extra itable entry so we can null-terminate it.
1136   int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1137 
1138   // Statistics
1139   update_stats(itable_size * HeapWordSize);
1140 
1141   return itable_size;
1142 }
1143 
1144 
1145 // Fill out offset table and interface klasses into the itable space
1146 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
1147   if (klass->itable_length() == 0) return;
1148   assert(!klass->is_interface(), "Should have zero length itable");
1149 
1150   // Count no of interfaces and total number of interface methods
1151   CountInterfacesClosure cic;
1152   visit_all_interfaces(klass->transitive_interfaces(), &cic);
1153   int nof_methods    = cic.nof_methods();
1154   int nof_interfaces = cic.nof_interfaces();
1155 
1156   // Add one extra entry so we can null-terminate the table
1157   nof_interfaces++;
1158 
1159   assert(compute_itable_size(objArrayHandle(klass->transitive_interfaces())) ==
1160          calc_itable_size(nof_interfaces, nof_methods),
1161          "mismatch calculation of itable size");
1162 
1163   // Fill-out offset table
1164   itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1165   itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1166   intptr_t* end               = klass->end_of_itable();
1167   assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1168   assert((oop*)(end) == (oop*)(ime + nof_methods),                      "wrong offset calculation (2)");
1169 
1170   // Visit all interfaces and initialize itable offset table
1171   SetupItableClosure sic((address)klass->as_klassOop(), ioe, ime);
1172   visit_all_interfaces(klass->transitive_interfaces(), &sic);
1173 
1174 #ifdef ASSERT
1175   ime  = sic.method_entry();
1176   oop* v = (oop*) klass->end_of_itable();
1177   assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1178 #endif
1179 }
1180 
1181 
1182 // m must be a method in an interface
1183 int klassItable::compute_itable_index(methodOop m) {
1184   klassOop intf = m->method_holder();
1185   assert(instanceKlass::cast(intf)->is_interface(), "sanity check");
1186   objArrayOop methods = instanceKlass::cast(intf)->methods();
1187   int index = 0;
1188   while(methods->obj_at(index) != m) {
1189     index++;
1190     assert(index < methods->length(), "should find index for resolve_invoke");
1191   }
1192   // Adjust for <clinit>, which is left out of table if first method
1193   if (methods->length() > 0 && ((methodOop)methods->obj_at(0))->is_static_initializer()) {
1194     index--;
1195   }
1196   return index;
1197 }
1198 
1199 
1200 // inverse to compute_itable_index
1201 methodOop klassItable::method_for_itable_index(klassOop intf, int itable_index) {
1202   assert(instanceKlass::cast(intf)->is_interface(), "sanity check");
1203   objArrayOop methods = instanceKlass::cast(intf)->methods();
1204 
1205   int index = itable_index;
1206   // Adjust for <clinit>, which is left out of table if first method
1207   if (methods->length() > 0 && ((methodOop)methods->obj_at(0))->is_static_initializer()) {
1208     index++;
1209   }
1210 
1211   if (itable_index < 0 || index >= methods->length())
1212     return NULL;                // help caller defend against bad indexes
1213 
1214   methodOop m = (methodOop)methods->obj_at(index);
1215   assert(compute_itable_index(m) == itable_index, "correct inverse");
1216 
1217   return m;
1218 }
1219 
1220 void klassVtable::verify(outputStream* st, bool forced) {
1221   // make sure table is initialized
1222   if (!Universe::is_fully_initialized()) return;
1223 #ifndef PRODUCT
1224   // avoid redundant verifies
1225   if (!forced && _verify_count == Universe::verify_count()) return;
1226   _verify_count = Universe::verify_count();
1227 #endif
1228   oop* end_of_obj = (oop*)_klass() + _klass()->size();
1229   oop* end_of_vtable = (oop *)&table()[_length];
1230   if (end_of_vtable > end_of_obj) {
1231     fatal(err_msg("klass %s: klass object too short (vtable extends beyond "
1232                   "end)", _klass->internal_name()));
1233   }
1234 
1235   for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1236   // verify consistency with superKlass vtable
1237   klassOop super = _klass->super();
1238   if (super != NULL) {
1239     instanceKlass* sk = instanceKlass::cast(super);
1240     klassVtable* vt = sk->vtable();
1241     for (int i = 0; i < vt->length(); i++) {
1242       verify_against(st, vt, i);
1243     }
1244   }
1245 }
1246 
1247 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1248   vtableEntry* vte = &vt->table()[index];
1249   if (vte->method()->name()      != table()[index].method()->name() ||
1250       vte->method()->signature() != table()[index].method()->signature()) {
1251     fatal("mismatched name/signature of vtable entries");
1252   }
1253 }
1254 
1255 #ifndef PRODUCT
1256 void klassVtable::print() {
1257   ResourceMark rm;
1258   tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1259   for (int i = 0; i < length(); i++) {
1260     table()[i].print();
1261     tty->cr();
1262   }
1263 }
1264 #endif
1265 
1266 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1267   NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1268   assert(method() != NULL, "must have set method");
1269   method()->verify();
1270   // we sub_type, because it could be a miranda method
1271   if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1272 #ifndef PRODUCT
1273     print();
1274 #endif
1275     fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
1276   }
1277 }
1278 
1279 #ifndef PRODUCT
1280 
1281 void vtableEntry::print() {
1282   ResourceMark rm;
1283   tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1284   if (Verbose) {
1285     tty->print("m %#lx ", (address)method());
1286   }
1287 }
1288 
1289 class VtableStats : AllStatic {
1290  public:
1291   static int no_klasses;                // # classes with vtables
1292   static int no_array_klasses;          // # array classes
1293   static int no_instance_klasses;       // # instanceKlasses
1294   static int sum_of_vtable_len;         // total # of vtable entries
1295   static int sum_of_array_vtable_len;   // total # of vtable entries in array klasses only
1296   static int fixed;                     // total fixed overhead in bytes
1297   static int filler;                    // overhead caused by filler bytes
1298   static int entries;                   // total bytes consumed by vtable entries
1299   static int array_entries;             // total bytes consumed by array vtable entries
1300 
1301   static void do_class(klassOop k) {
1302     Klass* kl = k->klass_part();
1303     klassVtable* vt = kl->vtable();
1304     if (vt == NULL) return;
1305     no_klasses++;
1306     if (kl->oop_is_instance()) {
1307       no_instance_klasses++;
1308       kl->array_klasses_do(do_class);
1309     }
1310     if (kl->oop_is_array()) {
1311       no_array_klasses++;
1312       sum_of_array_vtable_len += vt->length();
1313     }
1314     sum_of_vtable_len += vt->length();
1315   }
1316 
1317   static void compute() {
1318     SystemDictionary::classes_do(do_class);
1319     fixed  = no_klasses * oopSize;      // vtable length
1320     // filler size is a conservative approximation
1321     filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(instanceKlass) - sizeof(arrayKlass) - 1);
1322     entries = sizeof(vtableEntry) * sum_of_vtable_len;
1323     array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1324   }
1325 };
1326 
1327 int VtableStats::no_klasses = 0;
1328 int VtableStats::no_array_klasses = 0;
1329 int VtableStats::no_instance_klasses = 0;
1330 int VtableStats::sum_of_vtable_len = 0;
1331 int VtableStats::sum_of_array_vtable_len = 0;
1332 int VtableStats::fixed = 0;
1333 int VtableStats::filler = 0;
1334 int VtableStats::entries = 0;
1335 int VtableStats::array_entries = 0;
1336 
1337 void klassVtable::print_statistics() {
1338   ResourceMark rm;
1339   HandleMark hm;
1340   VtableStats::compute();
1341   tty->print_cr("vtable statistics:");
1342   tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1343   int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1344   tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1345   tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1346   tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1347   tty->print_cr("%6d bytes total", total);
1348 }
1349 



























1350 int  klassItable::_total_classes;   // Total no. of classes with itables
1351 long klassItable::_total_size;      // Total no. of bytes used for itables
1352 
1353 void klassItable::print_statistics() {
1354  tty->print_cr("itable statistics:");
1355  tty->print_cr("%6d classes with itables", _total_classes);
1356  tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes);
1357 }
1358 
1359 #endif // PRODUCT
--- EOF ---