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, and none of C's superclasses implements I.
  53 // Let's say there is an abstract method m in I that neither C
  54 // nor any of its super classes implement (i.e there is no method of any access,
  55 // with 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(
  59     int* vtable_length_ret, int* num_new_mirandas,
  60     GrowableArray<Method*>* all_mirandas, Klass* super,
  61     Array<Method*>* methods, AccessFlags class_flags,
  62     Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
  63     TRAPS) {
  64   No_Safepoint_Verifier nsv;
  65 
  66   // set up default result values
  67   int vtable_length = 0;
  68 
  69   // start off with super's vtable length
  70   InstanceKlass* sk = (InstanceKlass*)super;
  71   vtable_length = super == NULL ? 0 : sk->vtable_length();
  72 
  73   // go thru each method in the methods table to see if it needs a new entry
  74   int len = methods->length();
  75   for (int i = 0; i < len; i++) {
  76     assert(methods->at(i)->is_method(), "must be a Method*");
  77     methodHandle mh(THREAD, methods->at(i));
  78 
  79     if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) {
  80       vtable_length += vtableEntry::size(); // we need a new entry
  81     }
  82   }
  83 
  84   GrowableArray<Method*> new_mirandas(20);
  85   // compute the number of mirandas methods that must be added to the end
  86   get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces);
  87   *num_new_mirandas = new_mirandas.length();
  88 
  89   // Interfaces do not need interface methods in their vtables
  90   // This includes miranda methods and during later processing, default methods
  91   if (!class_flags.is_interface()) {
  92     vtable_length += *num_new_mirandas * vtableEntry::size();
  93   }
  94 
  95   if (Universe::is_bootstrapping() && vtable_length == 0) {
  96     // array classes don't have their superclass set correctly during
  97     // bootstrapping
  98     vtable_length = Universe::base_vtable_size();
  99   }
 100 
 101   if (super == NULL && !Universe::is_bootstrapping() &&
 102       vtable_length != Universe::base_vtable_size()) {
 103     // Someone is attempting to redefine java.lang.Object incorrectly.  The
 104     // only way this should happen is from
 105     // SystemDictionary::resolve_from_stream(), which will detect this later
 106     // and throw a security exception.  So don't assert here to let
 107     // the exception occur.
 108     vtable_length = Universe::base_vtable_size();
 109   }
 110   assert(super != NULL || vtable_length == Universe::base_vtable_size(),
 111          "bad vtable size for class Object");
 112   assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
 113   assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
 114 
 115   *vtable_length_ret = vtable_length;
 116 }
 117 
 118 int klassVtable::index_of(Method* m, int len) const {
 119   assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
 120   return m->vtable_index();
 121 }
 122 
 123 // Copy super class's vtable to the first part (prefix) of this class's vtable,
 124 // and return the number of entries copied.  Expects that 'super' is the Java
 125 // super class (arrays can have "array" super classes that must be skipped).
 126 int klassVtable::initialize_from_super(KlassHandle super) {
 127   if (super.is_null()) {
 128     return 0;
 129   } else {
 130     // copy methods from superKlass
 131     // can't inherit from array class, so must be InstanceKlass
 132     assert(super->oop_is_instance(), "must be instance klass");
 133     InstanceKlass* sk = (InstanceKlass*)super();
 134     klassVtable* superVtable = sk->vtable();
 135     assert(superVtable->length() <= _length, "vtable too short");
 136 #ifdef ASSERT
 137     superVtable->verify(tty, true);
 138 #endif
 139     superVtable->copy_vtable_to(table());
 140 #ifndef PRODUCT
 141     if (PrintVtables && Verbose) {
 142       ResourceMark rm;
 143       tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length);
 144     }
 145 #endif
 146     return superVtable->length();
 147   }
 148 }
 149 
 150 //
 151 // Revised lookup semantics   introduced 1.3 (Kestrel beta)
 152 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
 153 
 154   // Note:  Arrays can have intermediate array supers.  Use java_super to skip them.
 155   KlassHandle super (THREAD, klass()->java_super());
 156   int nofNewEntries = 0;
 157 
 158   if (PrintVtables && !klass()->oop_is_array()) {
 159     ResourceMark rm(THREAD);
 160     tty->print_cr("Initializing: %s", _klass->name()->as_C_string());
 161   }
 162 
 163 #ifdef ASSERT
 164   oop* end_of_obj = (oop*)_klass() + _klass()->size();
 165   oop* end_of_vtable = (oop*)&table()[_length];
 166   assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
 167 #endif
 168 
 169   if (Universe::is_bootstrapping()) {
 170     // just clear everything
 171     for (int i = 0; i < _length; i++) table()[i].clear();
 172     return;
 173   }
 174 
 175   int super_vtable_len = initialize_from_super(super);
 176   if (klass()->oop_is_array()) {
 177     assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
 178   } else {
 179     assert(_klass->oop_is_instance(), "must be InstanceKlass");
 180 
 181     Array<Method*>* methods = ik()->methods();
 182     int len = methods->length();
 183     int initialized = super_vtable_len;
 184 
 185     // Check each of this class's methods against super;
 186     // if override, replace in copy of super vtable, otherwise append to end
 187     for (int i = 0; i < len; i++) {
 188       // update_inherited_vtable can stop for gc - ensure using handles
 189       HandleMark hm(THREAD);
 190       assert(methods->at(i)->is_method(), "must be a Method*");
 191       methodHandle mh(THREAD, methods->at(i));
 192 
 193       bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
 194 
 195       if (needs_new_entry) {
 196         put_method_at(mh(), initialized);
 197         mh()->set_vtable_index(initialized); // set primary vtable index
 198         initialized++;
 199       }
 200     }
 201 
 202     // update vtable with default_methods
 203     Array<Method*>* default_methods = ik()->default_methods();
 204     if (default_methods != NULL) {
 205       len = default_methods->length();
 206       if (len > 0) {
 207         Array<int>* def_vtable_indices = NULL;
 208         if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
 209           def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
 210         } else {
 211           assert(def_vtable_indices->length() == len, "reinit vtable len?");
 212         }
 213         for (int i = 0; i < len; i++) {
 214           HandleMark hm(THREAD);
 215           assert(default_methods->at(i)->is_method(), "must be a Method*");
 216           methodHandle mh(THREAD, default_methods->at(i));
 217 
 218           bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
 219 
 220           // needs new entry
 221           if (needs_new_entry) {
 222             put_method_at(mh(), initialized);
 223             def_vtable_indices->at_put(i, initialized); //set vtable index
 224             initialized++;
 225           }
 226         }
 227       }
 228     }
 229 
 230     // add miranda methods; it will also return the updated initialized
 231     // Interfaces do not need interface methods in their vtables
 232     // This includes miranda methods and during later processing, default methods
 233     if (!ik()->is_interface()) {
 234       initialized = fill_in_mirandas(initialized);
 235     }
 236 
 237     // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
 238     // package_private -> public/protected), the vtable might actually be smaller than our initial
 239     // calculation.
 240     assert(initialized <= _length, "vtable initialization failed");
 241     for(;initialized < _length; initialized++) {
 242       put_method_at(NULL, initialized);
 243     }
 244     NOT_PRODUCT(verify(tty, true));
 245   }
 246 }
 247 
 248 // Called for cases where a method does not override its superclass' vtable entry
 249 // For bytecodes not produced by javac together it is possible that a method does not override
 250 // the superclass's method, but might indirectly override a super-super class's vtable entry
 251 // If none found, return a null superk, else return the superk of the method this does override
 252 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
 253                             int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
 254   InstanceKlass* superk = initialsuper;
 255   while (superk != NULL && superk->super() != NULL) {
 256     InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
 257     klassVtable* ssVtable = supersuperklass->vtable();
 258     if (vtable_index < ssVtable->length()) {
 259       Method* super_method = ssVtable->method_at(vtable_index);
 260 #ifndef PRODUCT
 261       Symbol* name= target_method()->name();
 262       Symbol* signature = target_method()->signature();
 263       assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
 264 #endif
 265       if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
 266 #ifndef PRODUCT
 267         if (PrintVtables && Verbose) {
 268           ResourceMark rm(THREAD);
 269           char* sig = target_method()->name_and_sig_as_C_string();
 270           tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ",
 271            supersuperklass->internal_name(),
 272            _klass->internal_name(), sig, vtable_index);
 273            super_method->access_flags().print_on(tty);
 274            if (super_method->is_default_method()) {
 275              tty->print("default ");
 276            }
 277            tty->print("overriders flags: ");
 278            target_method->access_flags().print_on(tty);
 279            if (target_method->is_default_method()) {
 280              tty->print("default ");
 281            }
 282         }
 283 #endif /*PRODUCT*/
 284         break; // return found superk
 285       }
 286     } else  {
 287       // super class has no vtable entry here, stop transitive search
 288       superk = (InstanceKlass*)NULL;
 289       break;
 290     }
 291     // if no override found yet, continue to search up
 292     superk = InstanceKlass::cast(superk->super());
 293   }
 294 
 295   return superk;
 296 }
 297 
 298 // Update child's copy of super vtable for overrides
 299 // OR return true if a new vtable entry is required.
 300 // Only called for InstanceKlass's, i.e. not for arrays
 301 // If that changed, could not use _klass as handle for klass
 302 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method,
 303                                           int super_vtable_len, int default_index,
 304                                           bool checkconstraints, TRAPS) {
 305   ResourceMark rm;
 306   bool allocate_new = true;
 307   assert(klass->oop_is_instance(), "must be InstanceKlass");
 308 
 309   Array<int>* def_vtable_indices = NULL;
 310   bool is_default = false;
 311   // default methods are concrete methods in superinterfaces which are added to the vtable
 312   // with their real method_holder
 313   // Since vtable and itable indices share the same storage, don't touch
 314   // the default method's real vtable/itable index
 315   // default_vtable_indices stores the vtable value relative to this inheritor
 316   if (default_index >= 0 ) {
 317     is_default = true;
 318     def_vtable_indices = klass->default_vtable_indices();
 319     assert(def_vtable_indices != NULL, "def vtable alloc?");
 320     assert(default_index <= def_vtable_indices->length(), "def vtable len?");
 321   } else {
 322     assert(klass == target_method()->method_holder(), "caller resp.");
 323     // Initialize the method's vtable index to "nonvirtual".
 324     // If we allocate a vtable entry, we will update it to a non-negative number.
 325     target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
 326   }
 327 
 328   // Static and <init> methods are never in
 329   if (target_method()->is_static() || target_method()->name() ==  vmSymbols::object_initializer_name()) {
 330     return false;
 331   }
 332 
 333   if (target_method->is_final_method(klass->access_flags())) {
 334     // a final method never needs a new entry; final methods can be statically
 335     // resolved and they have to be present in the vtable only if they override
 336     // a super's method, in which case they re-use its entry
 337     allocate_new = false;
 338   } else if (klass->is_interface()) {
 339     allocate_new = false;  // see note below in needs_new_vtable_entry
 340     // An interface never allocates new vtable slots, only inherits old ones.
 341     // This method will either be assigned its own itable index later,
 342     // or be assigned an inherited vtable index in the loop below.
 343     // default methods inherited by classes store their vtable indices
 344     // in the inheritor's default_vtable_indices
 345     // default methods inherited by interfaces may already have a
 346     // valid itable index, if so, don't change it
 347     // overpass methods in an interface will be assigned an itable index later
 348     // by an inheriting class
 349     if (!is_default || !target_method()->has_itable_index()) {
 350       target_method()->set_vtable_index(Method::pending_itable_index);
 351     }
 352   }
 353 
 354   // we need a new entry if there is no superclass
 355   if (klass->super() == NULL) {
 356     return allocate_new;
 357   }
 358 
 359   // private methods in classes always have a new entry in the vtable
 360   // specification interpretation since classic has
 361   // private methods not overriding
 362   // JDK8 adds private methods in interfaces which require invokespecial
 363   if (target_method()->is_private()) {
 364     return allocate_new;
 365   }
 366 
 367   // search through the vtable and update overridden entries
 368   // Since check_signature_loaders acquires SystemDictionary_lock
 369   // which can block for gc, once we are in this loop, use handles
 370   // For classfiles built with >= jdk7, we now look for transitive overrides
 371 
 372   Symbol* name = target_method()->name();
 373   Symbol* signature = target_method()->signature();
 374 
 375   KlassHandle target_klass(THREAD, target_method()->method_holder());
 376   if (target_klass == NULL) {
 377     target_klass = _klass;
 378   }
 379 
 380   Handle target_loader(THREAD, target_klass->class_loader());
 381 
 382   Symbol* target_classname = target_klass->name();
 383   for(int i = 0; i < super_vtable_len; i++) {
 384     Method* super_method = method_at(i);
 385     // Check if method name matches
 386     if (super_method->name() == name && super_method->signature() == signature) {
 387 
 388       // get super_klass for method_holder for the found method
 389       InstanceKlass* super_klass =  super_method->method_holder();
 390 
 391       if (is_default
 392           || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
 393           || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
 394           && ((super_klass = find_transitive_override(super_klass,
 395                              target_method, i, target_loader,
 396                              target_classname, THREAD))
 397                              != (InstanceKlass*)NULL))))
 398         {
 399         // overriding, so no new entry
 400         allocate_new = false;
 401 
 402         if (checkconstraints) {
 403         // Override vtable entry if passes loader constraint check
 404         // if loader constraint checking requested
 405         // No need to visit his super, since he and his super
 406         // have already made any needed loader constraints.
 407         // Since loader constraints are transitive, it is enough
 408         // to link to the first super, and we get all the others.
 409           Handle super_loader(THREAD, super_klass->class_loader());
 410 
 411           if (target_loader() != super_loader()) {
 412             ResourceMark rm(THREAD);
 413             Symbol* failed_type_symbol =
 414               SystemDictionary::check_signature_loaders(signature, target_loader,
 415                                                         super_loader, true,
 416                                                         CHECK_(false));
 417             if (failed_type_symbol != NULL) {
 418               const char* msg = "loader constraint violation: when resolving "
 419                 "overridden method \"%s\" the class loader (instance"
 420                 " of %s) of the current class, %s, and its superclass loader "
 421                 "(instance of %s), have different Class objects for the type "
 422                 "%s used in the signature";
 423               char* sig = target_method()->name_and_sig_as_C_string();
 424               const char* loader1 = SystemDictionary::loader_name(target_loader());
 425               char* current = target_klass->name()->as_C_string();
 426               const char* loader2 = SystemDictionary::loader_name(super_loader());
 427               char* failed_type_name = failed_type_symbol->as_C_string();
 428               size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
 429                 strlen(current) + strlen(loader2) + strlen(failed_type_name);
 430               char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
 431               jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
 432                            failed_type_name);
 433               THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
 434             }
 435           }
 436        }
 437 
 438        put_method_at(target_method(), i);
 439        if (!is_default) {
 440          target_method()->set_vtable_index(i);
 441        } else {
 442          if (def_vtable_indices != NULL) {
 443            def_vtable_indices->at_put(default_index, i);
 444          }
 445          assert(super_method->is_default_method() || super_method->is_overpass()
 446                 || super_method->is_abstract(), "default override error");
 447        }
 448 
 449 
 450 #ifndef PRODUCT
 451         if (PrintVtables && Verbose) {
 452           ResourceMark rm(THREAD);
 453           char* sig = target_method()->name_and_sig_as_C_string();
 454           tty->print("overriding with %s::%s index %d, original flags: ",
 455            target_klass->internal_name(), sig, i);
 456            super_method->access_flags().print_on(tty);
 457            if (super_method->is_default_method()) {
 458              tty->print("default ");
 459            }
 460            if (super_method->is_overpass()) {
 461              tty->print("overpass");
 462            }
 463            tty->print("overriders flags: ");
 464            target_method->access_flags().print_on(tty);
 465            if (target_method->is_default_method()) {
 466              tty->print("default ");
 467            }
 468            if (target_method->is_overpass()) {
 469              tty->print("overpass");
 470            }
 471            tty->cr();
 472         }
 473 #endif /*PRODUCT*/
 474       } else {
 475         // allocate_new = true; default. We might override one entry,
 476         // but not override another. Once we override one, not need new
 477 #ifndef PRODUCT
 478         if (PrintVtables && Verbose) {
 479           ResourceMark rm(THREAD);
 480           char* sig = target_method()->name_and_sig_as_C_string();
 481           tty->print("NOT overriding with %s::%s index %d, original flags: ",
 482            target_klass->internal_name(), sig,i);
 483            super_method->access_flags().print_on(tty);
 484            if (super_method->is_default_method()) {
 485              tty->print("default ");
 486            }
 487            if (super_method->is_overpass()) {
 488              tty->print("overpass");
 489            }
 490            tty->print("overriders flags: ");
 491            target_method->access_flags().print_on(tty);
 492            if (target_method->is_default_method()) {
 493              tty->print("default ");
 494            }
 495            if (target_method->is_overpass()) {
 496              tty->print("overpass");
 497            }
 498            tty->cr();
 499         }
 500 #endif /*PRODUCT*/
 501       }
 502     }
 503   }
 504   return allocate_new;
 505 }
 506 
 507 void klassVtable::put_method_at(Method* m, int index) {
 508 #ifndef PRODUCT
 509   if (PrintVtables && Verbose) {
 510     ResourceMark rm;
 511     const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
 512     tty->print("adding %s at index %d, flags: ", sig, index);
 513     if (m != NULL) {
 514       m->access_flags().print_on(tty);
 515       if (m->is_default_method()) {
 516         tty->print("default ");
 517       }
 518       if (m->is_overpass()) {
 519         tty->print("overpass");
 520       }
 521     }
 522     tty->cr();
 523   }
 524 #endif
 525   table()[index].set(m);
 526 }
 527 
 528 // Find out if a method "m" with superclass "super", loader "classloader" and
 529 // name "classname" needs a new vtable entry.  Let P be a class package defined
 530 // by "classloader" and "classname".
 531 // NOTE: The logic used here is very similar to the one used for computing
 532 // the vtables indices for a method. We cannot directly use that function because,
 533 // we allocate the InstanceKlass at load time, and that requires that the
 534 // superclass has been loaded.
 535 // However, the vtable entries are filled in at link time, and therefore
 536 // the superclass' vtable may not yet have been filled in.
 537 bool klassVtable::needs_new_vtable_entry(methodHandle target_method,
 538                                          Klass* super,
 539                                          Handle classloader,
 540                                          Symbol* classname,
 541                                          AccessFlags class_flags,
 542                                          TRAPS) {
 543   if (class_flags.is_interface()) {
 544     // Interfaces do not use vtables, so there is no point to assigning
 545     // a vtable index to any of their methods.  If we refrain from doing this,
 546     // we can use Method::_vtable_index to hold the itable index
 547     return false;
 548   }
 549 
 550   if (target_method->is_final_method(class_flags) ||
 551       // a final method never needs a new entry; final methods can be statically
 552       // resolved and they have to be present in the vtable only if they override
 553       // a super's method, in which case they re-use its entry
 554       (target_method()->is_static()) ||
 555       // static methods don't need to be in vtable
 556       (target_method()->name() ==  vmSymbols::object_initializer_name())
 557       // <init> is never called dynamically-bound
 558       ) {
 559     return false;
 560   }
 561 
 562   // Concrete interface methods do not need new entries, they override
 563   // abstract method entries using default inheritance rules
 564   if (target_method()->method_holder() != NULL &&
 565       target_method()->method_holder()->is_interface()  &&
 566       !target_method()->is_abstract() ) {
 567     return false;
 568   }
 569 
 570   // we need a new entry if there is no superclass
 571   if (super == NULL) {
 572     return true;
 573   }
 574 
 575   // private methods in classes always have a new entry in the vtable
 576   // specification interpretation since classic has
 577   // private methods not overriding
 578   // JDK8 adds private  methods in interfaces which require invokespecial
 579   if (target_method()->is_private()) {
 580     return true;
 581   }
 582 
 583   // search through the super class hierarchy to see if we need
 584   // a new entry
 585   ResourceMark rm;
 586   Symbol* name = target_method()->name();
 587   Symbol* signature = target_method()->signature();
 588   Klass* k = super;
 589   Method* super_method = NULL;
 590   InstanceKlass *holder = NULL;
 591   Method* recheck_method =  NULL;
 592   while (k != NULL) {
 593     // lookup through the hierarchy for a method with matching name and sign.
 594     super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
 595     if (super_method == NULL) {
 596       break; // we still have to search for a matching miranda method
 597     }
 598     // get the class holding the matching method
 599     // make sure you use that class for is_override
 600     InstanceKlass* superk = super_method->method_holder();
 601     // we want only instance method matches
 602     // pretend private methods are not in the super vtable
 603     // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
 604     // ignore private, c.m pub does override a.m pub
 605     // For classes that were not javac'd together, we also do transitive overriding around
 606     // methods that have less accessibility
 607     if ((!super_method->is_static()) &&
 608        (!super_method->is_private())) {
 609       if (superk->is_override(super_method, classloader, classname, THREAD)) {
 610         return false;
 611       // else keep looking for transitive overrides
 612       }
 613     }
 614 
 615     // Start with lookup result and continue to search up
 616     k = superk->super(); // haven't found an override match yet; continue to look
 617   }
 618 
 619   // if the target method is public or protected it may have a matching
 620   // miranda method in the super, whose entry it should re-use.
 621   // Actually, to handle cases that javac would not generate, we need
 622   // this check for all access permissions.
 623   InstanceKlass *sk = InstanceKlass::cast(super);
 624   if (sk->has_miranda_methods()) {
 625     if (sk->lookup_method_in_all_interfaces(name, signature, false) != NULL) {
 626       return false;  // found a matching miranda; we do not need a new entry
 627     }
 628   }
 629   return true; // found no match; we need a new entry
 630 }
 631 
 632 // Support for miranda methods
 633 
 634 // get the vtable index of a miranda method with matching "name" and "signature"
 635 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
 636   // search from the bottom, might be faster
 637   for (int i = (length() - 1); i >= 0; i--) {
 638     Method* m = table()[i].method();
 639     if (is_miranda_entry_at(i) &&
 640         m->name() == name && m->signature() == signature) {
 641       return i;
 642     }
 643   }
 644   return Method::invalid_vtable_index;
 645 }
 646 
 647 // check if an entry at an index is miranda
 648 // requires that method m at entry be declared ("held") by an interface.
 649 bool klassVtable::is_miranda_entry_at(int i) {
 650   Method* m = method_at(i);
 651   Klass* method_holder = m->method_holder();
 652   InstanceKlass *mhk = InstanceKlass::cast(method_holder);
 653 
 654   // miranda methods are public abstract instance interface methods in a class's vtable
 655   if (mhk->is_interface()) {
 656     assert(m->is_public(), "should be public");
 657     assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
 658     // the search could find a miranda or a default method
 659     if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) {
 660       return true;
 661     }
 662   }
 663   return false;
 664 }
 665 
 666 // check if a method is a miranda method, given a class's methods table,
 667 // its default_method table  and its super
 668 // Miranda methods are calculated twice:
 669 // first: before vtable size calculation: including abstract and default
 670 // This is seen by default method creation
 671 // Second: recalculated during vtable initialization: only abstract
 672 // This is seen by link resolution and selection.
 673 // "miranda" means not static, not defined by this class.
 674 // private methods in interfaces do not belong in the miranda list.
 675 // the caller must make sure that the method belongs to an interface implemented by the class
 676 // Miranda methods only include public interface instance methods
 677 // Not private methods, not static methods, not default == concrete abstract
 678 // Miranda methods also do not include overpass methods in interfaces
 679 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
 680                              Array<Method*>* default_methods, Klass* super) {
 681   if (m->is_static() || m->is_private() || m->is_overpass()) {
 682     return false;
 683   }
 684   Symbol* name = m->name();
 685   Symbol* signature = m->signature();
 686 
 687   if (InstanceKlass::find_instance_method(class_methods, name, signature) == NULL) {
 688     // did not find it in the method table of the current class
 689     if ((default_methods == NULL) ||
 690         InstanceKlass::find_method(default_methods, name, signature) == NULL) {
 691       if (super == NULL) {
 692         // super doesn't exist
 693         return true;
 694       }
 695 
 696       Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature);
 697       while (mo != NULL && mo->access_flags().is_static()
 698              && mo->method_holder() != NULL
 699              && mo->method_holder()->super() != NULL)
 700       {
 701          mo = mo->method_holder()->super()->uncached_lookup_method(name, signature);
 702       }
 703       if (mo == NULL || mo->access_flags().is_private() ) {
 704         // super class hierarchy does not implement it or protection is different
 705         return true;
 706       }
 707     }
 708   }
 709 
 710   return false;
 711 }
 712 
 713 // Scans current_interface_methods for miranda methods that do not
 714 // already appear in new_mirandas, or default methods,  and are also not defined-and-non-private
 715 // in super (superclass).  These mirandas are added to all_mirandas if it is
 716 // not null; in addition, those that are not duplicates of miranda methods
 717 // inherited by super from its interfaces are added to new_mirandas.
 718 // Thus, new_mirandas will be the set of mirandas that this class introduces,
 719 // all_mirandas will be the set of all mirandas applicable to this class
 720 // including all defined in superclasses.
 721 void klassVtable::add_new_mirandas_to_lists(
 722     GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
 723     Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
 724     Array<Method*>* default_methods, Klass* super) {
 725 
 726   // iterate thru the current interface's method to see if it a miranda
 727   int num_methods = current_interface_methods->length();
 728   for (int i = 0; i < num_methods; i++) {
 729     Method* im = current_interface_methods->at(i);
 730     bool is_duplicate = false;
 731     int num_of_current_mirandas = new_mirandas->length();
 732     // check for duplicate mirandas in different interfaces we implement
 733     for (int j = 0; j < num_of_current_mirandas; j++) {
 734       Method* miranda = new_mirandas->at(j);
 735       if ((im->name() == miranda->name()) &&
 736           (im->signature() == miranda->signature())) {
 737         is_duplicate = true;
 738         break;
 739       }
 740     }
 741 
 742     if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
 743       if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all?
 744         InstanceKlass *sk = InstanceKlass::cast(super);
 745         // check if it is a duplicate of a super's miranda
 746         if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), false) == NULL) {
 747           new_mirandas->append(im);
 748         }
 749         if (all_mirandas != NULL) {
 750           all_mirandas->append(im);
 751         }
 752       }
 753     }
 754   }
 755 }
 756 
 757 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
 758                                GrowableArray<Method*>* all_mirandas,
 759                                Klass* super, Array<Method*>* class_methods,
 760                                Array<Method*>* default_methods,
 761                                Array<Klass*>* local_interfaces) {
 762   assert((new_mirandas->length() == 0) , "current mirandas must be 0");
 763 
 764   // iterate thru the local interfaces looking for a miranda
 765   int num_local_ifs = local_interfaces->length();
 766   for (int i = 0; i < num_local_ifs; i++) {
 767     InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
 768     add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 769                               ik->methods(), class_methods,
 770                               default_methods, super);
 771     // iterate thru each local's super interfaces
 772     Array<Klass*>* super_ifs = ik->transitive_interfaces();
 773     int num_super_ifs = super_ifs->length();
 774     for (int j = 0; j < num_super_ifs; j++) {
 775       InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
 776       add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 777                                 sik->methods(), class_methods,
 778                                 default_methods, super);
 779     }
 780   }
 781 }
 782 
 783 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
 784 // and append them into the vtable starting at index initialized,
 785 // return the new value of initialized.
 786 // Miranda methods use vtable entries, but do not get assigned a vtable_index
 787 // The vtable_index is discovered by searching from the end of the vtable
 788 int klassVtable::fill_in_mirandas(int initialized) {
 789   GrowableArray<Method*> mirandas(20);
 790   get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
 791                ik()->default_methods(), ik()->local_interfaces());
 792   for (int i = 0; i < mirandas.length(); i++) {
 793     if (PrintVtables && Verbose) {
 794       Method* meth = mirandas.at(i);
 795       ResourceMark rm(Thread::current());
 796       if (meth != NULL) {
 797         char* sig = meth->name_and_sig_as_C_string();
 798         tty->print("fill in mirandas with %s index %d, flags: ",
 799           sig, initialized);
 800         meth->access_flags().print_on(tty);
 801         if (meth->is_default_method()) {
 802           tty->print("default ");
 803         }
 804         tty->cr();
 805       }
 806     }
 807     put_method_at(mirandas.at(i), initialized);
 808     ++initialized;
 809   }
 810   return initialized;
 811 }
 812 
 813 // Copy this class's vtable to the vtable beginning at start.
 814 // Used to copy superclass vtable to prefix of subclass's vtable.
 815 void klassVtable::copy_vtable_to(vtableEntry* start) {
 816   Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
 817 }
 818 
 819 #if INCLUDE_JVMTI
 820 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
 821   // If old_method is default, find this vtable index in default_vtable_indices
 822   // and replace that method in the _default_methods list
 823   bool updated = false;
 824 
 825   Array<Method*>* default_methods = ik()->default_methods();
 826   if (default_methods != NULL) {
 827     int len = default_methods->length();
 828     for (int idx = 0; idx < len; idx++) {
 829       if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
 830         if (default_methods->at(idx) == old_method) {
 831           default_methods->at_put(idx, new_method);
 832           updated = true;
 833         }
 834         break;
 835       }
 836     }
 837   }
 838   return updated;
 839 }
 840 void klassVtable::adjust_method_entries(Method** old_methods, Method** new_methods,
 841                                         int methods_length, bool * trace_name_printed) {
 842   // search the vtable for uses of either obsolete or EMCP methods
 843   for (int j = 0; j < methods_length; j++) {
 844     Method* old_method = old_methods[j];
 845     Method* new_method = new_methods[j];
 846 
 847     // In the vast majority of cases we could get the vtable index
 848     // by using:  old_method->vtable_index()
 849     // However, there are rare cases, eg. sun.awt.X11.XDecoratedPeer.getX()
 850     // in sun.awt.X11.XFramePeer where methods occur more than once in the
 851     // vtable, so, alas, we must do an exhaustive search.
 852     for (int index = 0; index < length(); index++) {
 853       if (unchecked_method_at(index) == old_method) {
 854         put_method_at(new_method, index);
 855           // For default methods, need to update the _default_methods array
 856           // which can only have one method entry for a given signature
 857           bool updated_default = false;
 858           if (old_method->is_default_method()) {
 859             updated_default = adjust_default_method(index, old_method, new_method);
 860           }
 861 
 862         if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
 863           if (!(*trace_name_printed)) {
 864             // RC_TRACE_MESG macro has an embedded ResourceMark
 865             RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s",
 866                            klass()->external_name(),
 867                            old_method->method_holder()->external_name()));
 868             *trace_name_printed = true;
 869           }
 870           // RC_TRACE macro has an embedded ResourceMark
 871           RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s",
 872                                 new_method->name()->as_C_string(),
 873                                 new_method->signature()->as_C_string(),
 874                                 updated_default ? "true" : "false"));
 875         }
 876         // cannot 'break' here; see for-loop comment above.
 877       }
 878     }
 879   }
 880 }
 881 
 882 // a vtable should never contain old or obsolete methods
 883 bool klassVtable::check_no_old_or_obsolete_entries() {
 884   for (int i = 0; i < length(); i++) {
 885     Method* m = unchecked_method_at(i);
 886     if (m != NULL &&
 887         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
 888       return false;
 889     }
 890   }
 891   return true;
 892 }
 893 
 894 void klassVtable::dump_vtable() {
 895   tty->print_cr("vtable dump --");
 896   for (int i = 0; i < length(); i++) {
 897     Method* m = unchecked_method_at(i);
 898     if (m != NULL) {
 899       tty->print("      (%5d)  ", i);
 900       m->access_flags().print_on(tty);
 901       if (m->is_default_method()) {
 902         tty->print("default ");
 903       }
 904       if (m->is_overpass()) {
 905         tty->print("overpass");
 906       }
 907       tty->print(" --  ");
 908       m->print_name(tty);
 909       tty->cr();
 910     }
 911   }
 912 }
 913 #endif // INCLUDE_JVMTI
 914 
 915 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
 916 void klassVtable::clear_vtable() {
 917   for (int i = 0; i < _length; i++) table()[i].clear();
 918 }
 919 
 920 bool klassVtable::is_initialized() {
 921   return _length == 0 || table()[0].method() != NULL;
 922 }
 923 
 924 //-----------------------------------------------------------------------------------------
 925 // Itable code
 926 
 927 // Initialize a itableMethodEntry
 928 void itableMethodEntry::initialize(Method* m) {
 929   if (m == NULL) return;
 930 
 931   _method = m;
 932 }
 933 
 934 klassItable::klassItable(instanceKlassHandle klass) {
 935   _klass = klass;
 936 
 937   if (klass->itable_length() > 0) {
 938     itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
 939     if (offset_entry  != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
 940       // First offset entry points to the first method_entry
 941       intptr_t* method_entry  = (intptr_t *)(((address)klass()) + offset_entry->offset());
 942       intptr_t* end         = klass->end_of_itable();
 943 
 944       _table_offset      = (intptr_t*)offset_entry - (intptr_t*)klass();
 945       _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
 946       _size_method_table = (end - method_entry)                  / itableMethodEntry::size();
 947       assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
 948       return;
 949     }
 950   }
 951 
 952   // The length of the itable was either zero, or it has not yet been initialized.
 953   _table_offset      = 0;
 954   _size_offset_table = 0;
 955   _size_method_table = 0;
 956 }
 957 
 958 static int initialize_count = 0;
 959 
 960 // Initialization
 961 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
 962   if (_klass->is_interface()) {
 963     // This needs to go after vtable indices are assigned but
 964     // before implementors need to know the number of itable indices.
 965     assign_itable_indices_for_interface(_klass());
 966   }
 967 
 968   // Cannot be setup doing bootstrapping, interfaces don't have
 969   // itables, and klass with only ones entry have empty itables
 970   if (Universe::is_bootstrapping() ||
 971       _klass->is_interface() ||
 972       _klass->itable_length() == itableOffsetEntry::size()) return;
 973 
 974   // There's alway an extra itable entry so we can null-terminate it.
 975   guarantee(size_offset_table() >= 1, "too small");
 976   int num_interfaces = size_offset_table() - 1;
 977   if (num_interfaces > 0) {
 978     if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count,
 979                                     _klass->name()->as_C_string());
 980 
 981 
 982     // Iterate through all interfaces
 983     int i;
 984     for(i = 0; i < num_interfaces; i++) {
 985       itableOffsetEntry* ioe = offset_entry(i);
 986       HandleMark hm(THREAD);
 987       KlassHandle interf_h (THREAD, ioe->interface_klass());
 988       assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable");
 989       initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK);
 990     }
 991 
 992   }
 993   // Check that the last entry is empty
 994   itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
 995   guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
 996 }
 997 
 998 
 999 inline bool interface_method_needs_itable_index(Method* m) {
1000   if (m->is_static())           return false;   // e.g., Stream.empty
1001   if (m->is_initializer())      return false;   // <init> or <clinit>
1002   // If an interface redeclares a method from java.lang.Object,
1003   // it should already have a vtable index, don't touch it.
1004   // e.g., CharSequence.toString (from initialize_vtable)
1005   // if (m->has_vtable_index())  return false; // NO!
1006   return true;
1007 }
1008 
1009 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1010   // an interface does not have an itable, but its methods need to be numbered
1011   if (TraceItables) tty->print_cr("%3d: Initializing itable for interface %s", ++initialize_count,
1012                                   klass->name()->as_C_string());
1013   Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1014   int nof_methods = methods->length();
1015   int ime_num = 0;
1016   for (int i = 0; i < nof_methods; i++) {
1017     Method* m = methods->at(i);
1018     if (interface_method_needs_itable_index(m)) {
1019       assert(!m->is_final_method(), "no final interface methods");
1020       // If m is already assigned a vtable index, do not disturb it.
1021       if (TraceItables && Verbose) {
1022         ResourceMark rm;
1023         const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
1024         if (m->has_vtable_index()) {
1025           tty->print("itable index %d for method: %s, flags: ", m->vtable_index(), sig);
1026         } else {
1027           tty->print("itable index %d for method: %s, flags: ", ime_num, sig);
1028         }
1029         if (m != NULL) {
1030           m->access_flags().print_on(tty);
1031           if (m->is_default_method()) {
1032             tty->print("default ");
1033           }
1034           if (m->is_overpass()) {
1035             tty->print("overpass");
1036           }
1037         }
1038         tty->cr();
1039       }
1040       if (!m->has_vtable_index()) {
1041         assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable");
1042         m->set_itable_index(ime_num);
1043         // Progress to next itable entry
1044         ime_num++;
1045       }
1046     }
1047   }
1048   assert(ime_num == method_count_for_interface(klass), "proper sizing");
1049   return ime_num;
1050 }
1051 
1052 int klassItable::method_count_for_interface(Klass* interf) {
1053   assert(interf->oop_is_instance(), "must be");
1054   assert(interf->is_interface(), "must be");
1055   Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1056   int nof_methods = methods->length();
1057   while (nof_methods > 0) {
1058     Method* m = methods->at(nof_methods-1);
1059     if (m->has_itable_index()) {
1060       int length = m->itable_index() + 1;
1061 #ifdef ASSERT
1062       while (nof_methods = 0) {
1063         m = methods->at(--nof_methods);
1064         assert(!m->has_itable_index() || m->itable_index() < length, "");
1065       }
1066 #endif //ASSERT
1067       return length;  // return the rightmost itable index, plus one
1068     }
1069     nof_methods -= 1;
1070   }
1071   // no methods have itable indices
1072   return 0;
1073 }
1074 
1075 
1076 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) {
1077   Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods();
1078   int nof_methods = methods->length();
1079   HandleMark hm;
1080   assert(nof_methods > 0, "at least one method must exist for interface to be in vtable");
1081   Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader());
1082 
1083   int ime_count = method_count_for_interface(interf_h());
1084   for (int i = 0; i < nof_methods; i++) {
1085     Method* m = methods->at(i);
1086     methodHandle target;
1087     if (m->has_itable_index()) {
1088       // This search must match the runtime resolution, i.e. selection search for invokeinterface
1089       // to correctly enforce loader constraints for interface method inheritance
1090       LinkResolver::lookup_instance_method_in_klasses(target, _klass, m->name(), m->signature(), CHECK);
1091     }
1092     if (target == NULL || !target->is_public() || target->is_abstract()) {
1093       // Entry does not resolve. Leave it empty for AbstractMethodError.
1094         if (!(target == NULL) && !target->is_public()) {
1095           // Stuff an IllegalAccessError throwing method in there instead.
1096           itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()].
1097               initialize(Universe::throw_illegal_access_error());
1098         }
1099     } else {
1100       // Entry did resolve, check loader constraints before initializing
1101       // if checkconstraints requested
1102       if (checkconstraints) {
1103         Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1104         if (method_holder_loader() != interface_loader()) {
1105           ResourceMark rm(THREAD);
1106           Symbol* failed_type_symbol =
1107             SystemDictionary::check_signature_loaders(m->signature(),
1108                                                       method_holder_loader,
1109                                                       interface_loader,
1110                                                       true, CHECK);
1111           if (failed_type_symbol != NULL) {
1112             const char* msg = "loader constraint violation in interface "
1113               "itable initialization: when resolving method \"%s\" the class"
1114               " loader (instance of %s) of the current class, %s, "
1115               "and the class loader (instance of %s) for interface "
1116               "%s have different Class objects for the type %s "
1117               "used in the signature";
1118             char* sig = target()->name_and_sig_as_C_string();
1119             const char* loader1 = SystemDictionary::loader_name(method_holder_loader());
1120             char* current = _klass->name()->as_C_string();
1121             const char* loader2 = SystemDictionary::loader_name(interface_loader());
1122             char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string();
1123             char* failed_type_name = failed_type_symbol->as_C_string();
1124             size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) +
1125               strlen(current) + strlen(loader2) + strlen(iface) +
1126               strlen(failed_type_name);
1127             char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1128             jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2,
1129                          iface, failed_type_name);
1130             THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1131           }
1132         }
1133       }
1134 
1135       // ime may have moved during GC so recalculate address
1136       int ime_num = m->itable_index();
1137       assert(ime_num < ime_count, "oob");
1138       itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target());
1139       if (TraceItables && Verbose) {
1140         ResourceMark rm(THREAD);
1141         if (target() != NULL) {
1142           char* sig = target()->name_and_sig_as_C_string();
1143           tty->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1144                     interf_h()->internal_name(), ime_num, sig,
1145                     target()->method_holder()->internal_name());
1146           tty->print("target_method flags: ");
1147           target()->access_flags().print_on(tty);
1148           if (target()->is_default_method()) {
1149             tty->print("default ");
1150           }
1151           tty->cr();
1152         }
1153       }
1154     }
1155   }
1156 }
1157 
1158 // Update entry for specific Method*
1159 void klassItable::initialize_with_method(Method* m) {
1160   itableMethodEntry* ime = method_entry(0);
1161   for(int i = 0; i < _size_method_table; i++) {
1162     if (ime->method() == m) {
1163       ime->initialize(m);
1164     }
1165     ime++;
1166   }
1167 }
1168 
1169 #if INCLUDE_JVMTI
1170 void klassItable::adjust_method_entries(Method** old_methods, Method** new_methods,
1171                                         int methods_length, bool * trace_name_printed) {
1172   // search the itable for uses of either obsolete or EMCP methods
1173   for (int j = 0; j < methods_length; j++) {
1174     Method* old_method = old_methods[j];
1175     Method* new_method = new_methods[j];
1176     itableMethodEntry* ime = method_entry(0);
1177 
1178     // The itable can describe more than one interface and the same
1179     // method signature can be specified by more than one interface.
1180     // This means we have to do an exhaustive search to find all the
1181     // old_method references.
1182     for (int i = 0; i < _size_method_table; i++) {
1183       if (ime->method() == old_method) {
1184         ime->initialize(new_method);
1185 
1186         if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
1187           if (!(*trace_name_printed)) {
1188             // RC_TRACE_MESG macro has an embedded ResourceMark
1189             RC_TRACE_MESG(("adjust: name=%s",
1190               old_method->method_holder()->external_name()));
1191             *trace_name_printed = true;
1192           }
1193           // RC_TRACE macro has an embedded ResourceMark
1194           RC_TRACE(0x00200000, ("itable method update: %s(%s)",
1195             new_method->name()->as_C_string(),
1196             new_method->signature()->as_C_string()));
1197         }
1198         // cannot 'break' here; see for-loop comment above.
1199       }
1200       ime++;
1201     }
1202   }
1203 }
1204 
1205 // an itable should never contain old or obsolete methods
1206 bool klassItable::check_no_old_or_obsolete_entries() {
1207   itableMethodEntry* ime = method_entry(0);
1208   for (int i = 0; i < _size_method_table; i++) {
1209     Method* m = ime->method();
1210     if (m != NULL &&
1211         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1212       return false;
1213     }
1214     ime++;
1215   }
1216   return true;
1217 }
1218 
1219 void klassItable::dump_itable() {
1220   itableMethodEntry* ime = method_entry(0);
1221   tty->print_cr("itable dump --");
1222   for (int i = 0; i < _size_method_table; i++) {
1223     Method* m = ime->method();
1224     if (m != NULL) {
1225       tty->print("      (%5d)  ", i);
1226       m->access_flags().print_on(tty);
1227       if (m->is_default_method()) {
1228         tty->print("default ");
1229       }
1230       tty->print(" --  ");
1231       m->print_name(tty);
1232       tty->cr();
1233     }
1234     ime++;
1235   }
1236 }
1237 #endif // INCLUDE_JVMTI
1238 
1239 
1240 // Setup
1241 class InterfaceVisiterClosure : public StackObj {
1242  public:
1243   virtual void doit(Klass* intf, int method_count) = 0;
1244 };
1245 
1246 // Visit all interfaces with at least one itable method
1247 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1248   // Handle array argument
1249   for(int i = 0; i < transitive_intf->length(); i++) {
1250     Klass* intf = transitive_intf->at(i);
1251     assert(intf->is_interface(), "sanity check");
1252 
1253     // Find no. of itable methods
1254     int method_count = 0;
1255     // method_count = klassItable::method_count_for_interface(intf);
1256     Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1257     if (methods->length() > 0) {
1258       for (int i = methods->length(); --i >= 0; ) {
1259         if (interface_method_needs_itable_index(methods->at(i))) {
1260           method_count++;
1261         }
1262       }
1263     }
1264 
1265     // Only count interfaces with at least one method
1266     if (method_count > 0) {
1267       blk->doit(intf, method_count);
1268     }
1269   }
1270 }
1271 
1272 class CountInterfacesClosure : public InterfaceVisiterClosure {
1273  private:
1274   int _nof_methods;
1275   int _nof_interfaces;
1276  public:
1277    CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1278 
1279    int nof_methods() const    { return _nof_methods; }
1280    int nof_interfaces() const { return _nof_interfaces; }
1281 
1282    void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1283 };
1284 
1285 class SetupItableClosure : public InterfaceVisiterClosure  {
1286  private:
1287   itableOffsetEntry* _offset_entry;
1288   itableMethodEntry* _method_entry;
1289   address            _klass_begin;
1290  public:
1291   SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1292     _klass_begin  = klass_begin;
1293     _offset_entry = offset_entry;
1294     _method_entry = method_entry;
1295   }
1296 
1297   itableMethodEntry* method_entry() const { return _method_entry; }
1298 
1299   void doit(Klass* intf, int method_count) {
1300     int offset = ((address)_method_entry) - _klass_begin;
1301     _offset_entry->initialize(intf, offset);
1302     _offset_entry++;
1303     _method_entry += method_count;
1304   }
1305 };
1306 
1307 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1308   // Count no of interfaces and total number of interface methods
1309   CountInterfacesClosure cic;
1310   visit_all_interfaces(transitive_interfaces, &cic);
1311 
1312   // There's alway an extra itable entry so we can null-terminate it.
1313   int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1314 
1315   // Statistics
1316   update_stats(itable_size * HeapWordSize);
1317 
1318   return itable_size;
1319 }
1320 
1321 
1322 // Fill out offset table and interface klasses into the itable space
1323 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) {
1324   if (klass->itable_length() == 0) return;
1325   assert(!klass->is_interface(), "Should have zero length itable");
1326 
1327   // Count no of interfaces and total number of interface methods
1328   CountInterfacesClosure cic;
1329   visit_all_interfaces(klass->transitive_interfaces(), &cic);
1330   int nof_methods    = cic.nof_methods();
1331   int nof_interfaces = cic.nof_interfaces();
1332 
1333   // Add one extra entry so we can null-terminate the table
1334   nof_interfaces++;
1335 
1336   assert(compute_itable_size(klass->transitive_interfaces()) ==
1337          calc_itable_size(nof_interfaces, nof_methods),
1338          "mismatch calculation of itable size");
1339 
1340   // Fill-out offset table
1341   itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1342   itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1343   intptr_t* end               = klass->end_of_itable();
1344   assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1345   assert((oop*)(end) == (oop*)(ime + nof_methods),                      "wrong offset calculation (2)");
1346 
1347   // Visit all interfaces and initialize itable offset table
1348   SetupItableClosure sic((address)klass(), ioe, ime);
1349   visit_all_interfaces(klass->transitive_interfaces(), &sic);
1350 
1351 #ifdef ASSERT
1352   ime  = sic.method_entry();
1353   oop* v = (oop*) klass->end_of_itable();
1354   assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1355 #endif
1356 }
1357 
1358 
1359 // inverse to itable_index
1360 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1361   assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1362   assert(intf->verify_itable_index(itable_index), "");
1363   Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1364 
1365   if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1366     return NULL;                // help caller defend against bad indices
1367 
1368   int index = itable_index;
1369   Method* m = methods->at(index);
1370   int index2 = -1;
1371   while (!m->has_itable_index() ||
1372          (index2 = m->itable_index()) != itable_index) {
1373     assert(index2 < itable_index, "monotonic");
1374     if (++index == methods->length())
1375       return NULL;
1376     m = methods->at(index);
1377   }
1378   assert(m->itable_index() == itable_index, "correct inverse");
1379 
1380   return m;
1381 }
1382 
1383 void klassVtable::verify(outputStream* st, bool forced) {
1384   // make sure table is initialized
1385   if (!Universe::is_fully_initialized()) return;
1386 #ifndef PRODUCT
1387   // avoid redundant verifies
1388   if (!forced && _verify_count == Universe::verify_count()) return;
1389   _verify_count = Universe::verify_count();
1390 #endif
1391   oop* end_of_obj = (oop*)_klass() + _klass()->size();
1392   oop* end_of_vtable = (oop *)&table()[_length];
1393   if (end_of_vtable > end_of_obj) {
1394     fatal(err_msg("klass %s: klass object too short (vtable extends beyond "
1395                   "end)", _klass->internal_name()));
1396   }
1397 
1398   for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1399   // verify consistency with superKlass vtable
1400   Klass* super = _klass->super();
1401   if (super != NULL) {
1402     InstanceKlass* sk = InstanceKlass::cast(super);
1403     klassVtable* vt = sk->vtable();
1404     for (int i = 0; i < vt->length(); i++) {
1405       verify_against(st, vt, i);
1406     }
1407   }
1408 }
1409 
1410 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1411   vtableEntry* vte = &vt->table()[index];
1412   if (vte->method()->name()      != table()[index].method()->name() ||
1413       vte->method()->signature() != table()[index].method()->signature()) {
1414     fatal("mismatched name/signature of vtable entries");
1415   }
1416 }
1417 
1418 #ifndef PRODUCT
1419 void klassVtable::print() {
1420   ResourceMark rm;
1421   tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1422   for (int i = 0; i < length(); i++) {
1423     table()[i].print();
1424     tty->cr();
1425   }
1426 }
1427 #endif
1428 
1429 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1430   NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1431   assert(method() != NULL, "must have set method");
1432   method()->verify();
1433   // we sub_type, because it could be a miranda method
1434   if (!vt->klass()->is_subtype_of(method()->method_holder())) {
1435 #ifndef PRODUCT
1436     print();
1437 #endif
1438     fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
1439   }
1440 }
1441 
1442 #ifndef PRODUCT
1443 
1444 void vtableEntry::print() {
1445   ResourceMark rm;
1446   tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1447   if (Verbose) {
1448     tty->print("m %#lx ", (address)method());
1449   }
1450 }
1451 
1452 class VtableStats : AllStatic {
1453  public:
1454   static int no_klasses;                // # classes with vtables
1455   static int no_array_klasses;          // # array classes
1456   static int no_instance_klasses;       // # instanceKlasses
1457   static int sum_of_vtable_len;         // total # of vtable entries
1458   static int sum_of_array_vtable_len;   // total # of vtable entries in array klasses only
1459   static int fixed;                     // total fixed overhead in bytes
1460   static int filler;                    // overhead caused by filler bytes
1461   static int entries;                   // total bytes consumed by vtable entries
1462   static int array_entries;             // total bytes consumed by array vtable entries
1463 
1464   static void do_class(Klass* k) {
1465     Klass* kl = k;
1466     klassVtable* vt = kl->vtable();
1467     if (vt == NULL) return;
1468     no_klasses++;
1469     if (kl->oop_is_instance()) {
1470       no_instance_klasses++;
1471       kl->array_klasses_do(do_class);
1472     }
1473     if (kl->oop_is_array()) {
1474       no_array_klasses++;
1475       sum_of_array_vtable_len += vt->length();
1476     }
1477     sum_of_vtable_len += vt->length();
1478   }
1479 
1480   static void compute() {
1481     SystemDictionary::classes_do(do_class);
1482     fixed  = no_klasses * oopSize;      // vtable length
1483     // filler size is a conservative approximation
1484     filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1485     entries = sizeof(vtableEntry) * sum_of_vtable_len;
1486     array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1487   }
1488 };
1489 
1490 int VtableStats::no_klasses = 0;
1491 int VtableStats::no_array_klasses = 0;
1492 int VtableStats::no_instance_klasses = 0;
1493 int VtableStats::sum_of_vtable_len = 0;
1494 int VtableStats::sum_of_array_vtable_len = 0;
1495 int VtableStats::fixed = 0;
1496 int VtableStats::filler = 0;
1497 int VtableStats::entries = 0;
1498 int VtableStats::array_entries = 0;
1499 
1500 void klassVtable::print_statistics() {
1501   ResourceMark rm;
1502   HandleMark hm;
1503   VtableStats::compute();
1504   tty->print_cr("vtable statistics:");
1505   tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1506   int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1507   tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1508   tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1509   tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1510   tty->print_cr("%6d bytes total", total);
1511 }
1512 
1513 int  klassItable::_total_classes;   // Total no. of classes with itables
1514 long klassItable::_total_size;      // Total no. of bytes used for itables
1515 
1516 void klassItable::print_statistics() {
1517  tty->print_cr("itable statistics:");
1518  tty->print_cr("%6d classes with itables", _total_classes);
1519  tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes);
1520 }
1521 
1522 #endif // PRODUCT