1 /*
   2  * Copyright (c) 1997, 2018, 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 "jvm.h"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "classfile/vmSymbols.hpp"
  29 #include "interpreter/linkResolver.hpp"
  30 #include "logging/log.hpp"
  31 #include "logging/logStream.hpp"
  32 #include "memory/metaspaceShared.hpp"
  33 #include "memory/resourceArea.hpp"
  34 #include "memory/universe.hpp"
  35 #include "oops/instanceKlass.hpp"
  36 #include "oops/klassVtable.hpp"
  37 #include "oops/method.hpp"
  38 #include "oops/objArrayOop.hpp"
  39 #include "oops/oop.inline.hpp"
  40 #include "runtime/arguments.hpp"
  41 #include "runtime/handles.inline.hpp"
  42 #include "runtime/safepointVerifiers.hpp"
  43 #include "utilities/copy.hpp"
  44 
  45 inline InstanceKlass* klassVtable::ik() const {
  46   return InstanceKlass::cast(_klass);
  47 }
  48 
  49 bool klassVtable::is_preinitialized_vtable() {
  50   return _klass->is_shared() && !MetaspaceShared::remapped_readwrite();
  51 }
  52 
  53 
  54 // this function computes the vtable size (including the size needed for miranda
  55 // methods) and the number of miranda methods in this class.
  56 // Note on Miranda methods: Let's say there is a class C that implements
  57 // interface I, and none of C's superclasses implements I.
  58 // Let's say there is an abstract method m in I that neither C
  59 // nor any of its super classes implement (i.e there is no method of any access,
  60 // with the same name and signature as m), then m is a Miranda method which is
  61 // entered as a public abstract method in C's vtable.  From then on it should
  62 // treated as any other public method in C for method over-ride purposes.
  63 void klassVtable::compute_vtable_size_and_num_mirandas(
  64     int* vtable_length_ret, int* num_new_mirandas,
  65     GrowableArray<Method*>* all_mirandas, const Klass* super,
  66     Array<Method*>* methods, AccessFlags class_flags, u2 major_version,
  67     Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces,
  68     TRAPS) {
  69   NoSafepointVerifier nsv;
  70 
  71   // set up default result values
  72   int vtable_length = 0;
  73 
  74   // start off with super's vtable length
  75   vtable_length = super == NULL ? 0 : super->vtable_length();
  76 
  77   // go thru each method in the methods table to see if it needs a new entry
  78   int len = methods->length();
  79   for (int i = 0; i < len; i++) {
  80     assert(methods->at(i)->is_method(), "must be a Method*");
  81     methodHandle mh(THREAD, methods->at(i));
  82 
  83     if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) {
  84       vtable_length += vtableEntry::size(); // we need a new entry
  85     }
  86   }
  87 
  88   GrowableArray<Method*> new_mirandas(20);
  89   // compute the number of mirandas methods that must be added to the end
  90   get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces,
  91                class_flags.is_interface());
  92   *num_new_mirandas = new_mirandas.length();
  93 
  94   // Interfaces do not need interface methods in their vtables
  95   // This includes miranda methods and during later processing, default methods
  96   if (!class_flags.is_interface()) {
  97      vtable_length += *num_new_mirandas * vtableEntry::size();
  98   }
  99 
 100   if (Universe::is_bootstrapping() && vtable_length == 0) {
 101     // array classes don't have their superclass set correctly during
 102     // bootstrapping
 103     vtable_length = Universe::base_vtable_size();
 104   }
 105 
 106   if (super == NULL && vtable_length != Universe::base_vtable_size()) {
 107     if (Universe::is_bootstrapping()) {
 108       // Someone is attempting to override java.lang.Object incorrectly on the
 109       // bootclasspath.  The JVM cannot recover from this error including throwing
 110       // an exception
 111       vm_exit_during_initialization("Incompatible definition of java.lang.Object");
 112     } else {
 113       // Someone is attempting to redefine java.lang.Object incorrectly.  The
 114       // only way this should happen is from
 115       // SystemDictionary::resolve_from_stream(), which will detect this later
 116       // and throw a security exception.  So don't assert here to let
 117       // the exception occur.
 118       vtable_length = Universe::base_vtable_size();
 119     }
 120   }
 121   assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
 122   assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
 123 
 124   *vtable_length_ret = vtable_length;
 125 }
 126 
 127 int klassVtable::index_of(Method* m, int len) const {
 128   assert(m->has_vtable_index(), "do not ask this of non-vtable methods");
 129   return m->vtable_index();
 130 }
 131 
 132 // Copy super class's vtable to the first part (prefix) of this class's vtable,
 133 // and return the number of entries copied.  Expects that 'super' is the Java
 134 // super class (arrays can have "array" super classes that must be skipped).
 135 int klassVtable::initialize_from_super(Klass* super) {
 136   if (super == NULL) {
 137     return 0;
 138   } else if (is_preinitialized_vtable()) {
 139     // A shared class' vtable is preinitialized at dump time. No need to copy
 140     // methods from super class for shared class, as that was already done
 141     // during archiving time. However, if Jvmti has redefined a class,
 142     // copy super class's vtable in case the super class has changed.
 143     return super->vtable().length();
 144   } else {
 145     // copy methods from superKlass
 146     klassVtable superVtable = super->vtable();
 147     assert(superVtable.length() <= _length, "vtable too short");
 148 #ifdef ASSERT
 149     superVtable.verify(tty, true);
 150 #endif
 151     superVtable.copy_vtable_to(table());
 152     if (log_develop_is_enabled(Trace, vtables)) {
 153       ResourceMark rm;
 154       log_develop_trace(vtables)("copy vtable from %s to %s size %d",
 155                                  super->internal_name(), klass()->internal_name(),
 156                                  _length);
 157     }
 158     return superVtable.length();
 159   }
 160 }
 161 
 162 //
 163 // Revised lookup semantics   introduced 1.3 (Kestrel beta)
 164 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) {
 165 
 166   // Note:  Arrays can have intermediate array supers.  Use java_super to skip them.
 167   Klass* super = _klass->java_super();
 168   int nofNewEntries = 0;
 169 
 170   bool is_shared = _klass->is_shared();
 171 
 172   if (!_klass->is_array_klass()) {
 173     ResourceMark rm(THREAD);
 174     log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string());
 175   }
 176 
 177 #ifdef ASSERT
 178   oop* end_of_obj = (oop*)_klass + _klass->size();
 179   oop* end_of_vtable = (oop*)&table()[_length];
 180   assert(end_of_vtable <= end_of_obj, "vtable extends beyond end");
 181 #endif
 182 
 183   if (Universe::is_bootstrapping()) {
 184     assert(!is_shared, "sanity");
 185     // just clear everything
 186     for (int i = 0; i < _length; i++) table()[i].clear();
 187     return;
 188   }
 189 
 190   int super_vtable_len = initialize_from_super(super);
 191   if (_klass->is_array_klass()) {
 192     assert(super_vtable_len == _length, "arrays shouldn't introduce new methods");
 193   } else {
 194     assert(_klass->is_instance_klass(), "must be InstanceKlass");
 195 
 196     Array<Method*>* methods = ik()->methods();
 197     int len = methods->length();
 198     int initialized = super_vtable_len;
 199 
 200     // Check each of this class's methods against super;
 201     // if override, replace in copy of super vtable, otherwise append to end
 202     for (int i = 0; i < len; i++) {
 203       // update_inherited_vtable can stop for gc - ensure using handles
 204       HandleMark hm(THREAD);
 205       assert(methods->at(i)->is_method(), "must be a Method*");
 206       methodHandle mh(THREAD, methods->at(i));
 207 
 208       bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK);
 209 
 210       if (needs_new_entry) {
 211         put_method_at(mh(), initialized);
 212         mh()->set_vtable_index(initialized); // set primary vtable index
 213         initialized++;
 214       }
 215     }
 216 
 217     // update vtable with default_methods
 218     Array<Method*>* default_methods = ik()->default_methods();
 219     if (default_methods != NULL) {
 220       len = default_methods->length();
 221       if (len > 0) {
 222         Array<int>* def_vtable_indices = NULL;
 223         if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) {
 224           assert(!is_shared, "shared class def_vtable_indices does not exist");
 225           def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK);
 226         } else {
 227           assert(def_vtable_indices->length() == len, "reinit vtable len?");
 228         }
 229         for (int i = 0; i < len; i++) {
 230           HandleMark hm(THREAD);
 231           assert(default_methods->at(i)->is_method(), "must be a Method*");
 232           methodHandle mh(THREAD, default_methods->at(i));
 233           assert(!mh->is_private(), "private interface method in the default method list");
 234           bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK);
 235 
 236           // needs new entry
 237           if (needs_new_entry) {
 238             put_method_at(mh(), initialized);
 239             if (is_preinitialized_vtable()) {
 240               // At runtime initialize_vtable is rerun for a shared class
 241               // (loaded by the non-boot loader) as part of link_class_impl().
 242               // The dumptime vtable index should be the same as the runtime index.
 243               assert(def_vtable_indices->at(i) == initialized,
 244                      "dump time vtable index is different from runtime index");
 245             } else {
 246               def_vtable_indices->at_put(i, initialized); //set vtable index
 247             }
 248             initialized++;
 249           }
 250         }
 251       }
 252     }
 253 
 254     // add miranda methods; it will also return the updated initialized
 255     // Interfaces do not need interface methods in their vtables
 256     // This includes miranda methods and during later processing, default methods
 257     if (!ik()->is_interface()) {
 258       initialized = fill_in_mirandas(initialized);
 259     }
 260 
 261     // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
 262     // package_private -> public/protected), the vtable might actually be smaller than our initial
 263     // calculation, for classfile versions for which we do not do transitive override
 264     // calculations.
 265     if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
 266       assert(initialized == _length, "vtable initialization failed");
 267     } else {
 268       assert(initialized <= _length, "vtable initialization failed");
 269       for(;initialized < _length; initialized++) {
 270         table()[initialized].clear();
 271       }
 272     }
 273     NOT_PRODUCT(verify(tty, true));
 274   }
 275 }
 276 
 277 // Called for cases where a method does not override its superclass' vtable entry
 278 // For bytecodes not produced by javac together it is possible that a method does not override
 279 // the superclass's method, but might indirectly override a super-super class's vtable entry
 280 // If none found, return a null superk, else return the superk of the method this does override
 281 // For public and protected methods: if they override a superclass, they will
 282 // also be overridden themselves appropriately.
 283 // Private methods do not override and are not overridden.
 284 // Package Private methods are trickier:
 285 // e.g. P1.A, pub m
 286 // P2.B extends A, package private m
 287 // P1.C extends B, public m
 288 // P1.C.m needs to override P1.A.m and can not override P2.B.m
 289 // Therefore: all package private methods need their own vtable entries for
 290 // them to be the root of an inheritance overriding decision
 291 // Package private methods may also override other vtable entries
 292 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, const methodHandle& target_method,
 293                             int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
 294   InstanceKlass* superk = initialsuper;
 295   while (superk != NULL && superk->super() != NULL) {
 296     InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super());
 297     klassVtable ssVtable = supersuperklass->vtable();
 298     if (vtable_index < ssVtable.length()) {
 299       Method* super_method = ssVtable.method_at(vtable_index);
 300 #ifndef PRODUCT
 301       Symbol* name= target_method()->name();
 302       Symbol* signature = target_method()->signature();
 303       assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch");
 304 #endif
 305       if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) {
 306         if (log_develop_is_enabled(Trace, vtables)) {
 307           ResourceMark rm(THREAD);
 308           LogTarget(Trace, vtables) lt;
 309           LogStream ls(lt);
 310           char* sig = target_method()->name_and_sig_as_C_string();
 311           ls.print("transitive overriding superclass %s with %s index %d, original flags: ",
 312                        supersuperklass->internal_name(),
 313                        sig, vtable_index);
 314           super_method->print_linkage_flags(&ls);
 315           ls.print("overriders flags: ");
 316           target_method->print_linkage_flags(&ls);
 317           ls.cr();
 318         }
 319 
 320         break; // return found superk
 321       }
 322     } else  {
 323       // super class has no vtable entry here, stop transitive search
 324       superk = (InstanceKlass*)NULL;
 325       break;
 326     }
 327     // if no override found yet, continue to search up
 328     superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super());
 329   }
 330 
 331   return superk;
 332 }
 333 
 334 static void log_vtables(int i, bool overrides, const methodHandle& target_method,
 335                         Klass* target_klass, Method* super_method,
 336                         Thread* thread) {
 337 #ifndef PRODUCT
 338   if (log_develop_is_enabled(Trace, vtables)) {
 339     ResourceMark rm(thread);
 340     LogTarget(Trace, vtables) lt;
 341     LogStream ls(lt);
 342     char* sig = target_method()->name_and_sig_as_C_string();
 343     if (overrides) {
 344       ls.print("overriding with %s index %d, original flags: ",
 345                    sig, i);
 346     } else {
 347       ls.print("NOT overriding with %s index %d, original flags: ",
 348                    sig, i);
 349     }
 350     super_method->print_linkage_flags(&ls);
 351     ls.print("overriders flags: ");
 352     target_method->print_linkage_flags(&ls);
 353     ls.cr();
 354   }
 355 #endif
 356 }
 357 
 358 // Update child's copy of super vtable for overrides
 359 // OR return true if a new vtable entry is required.
 360 // Only called for InstanceKlass's, i.e. not for arrays
 361 // If that changed, could not use _klass as handle for klass
 362 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, const methodHandle& target_method,
 363                                           int super_vtable_len, int default_index,
 364                                           bool checkconstraints, TRAPS) {
 365   ResourceMark rm;
 366   bool allocate_new = true;
 367   assert(klass->is_instance_klass(), "must be InstanceKlass");
 368 
 369   Array<int>* def_vtable_indices = NULL;
 370   bool is_default = false;
 371 
 372   // default methods are non-private concrete methods in superinterfaces which are added
 373   // to the vtable with their real method_holder.
 374   // Since vtable and itable indices share the same storage, don't touch
 375   // the default method's real vtable/itable index.
 376   // default_vtable_indices stores the vtable value relative to this inheritor
 377   if (default_index >= 0 ) {
 378     is_default = true;
 379     def_vtable_indices = klass->default_vtable_indices();
 380     assert(!target_method()->is_private(), "private interface method flagged as default");
 381     assert(def_vtable_indices != NULL, "def vtable alloc?");
 382     assert(default_index <= def_vtable_indices->length(), "def vtable len?");
 383   } else {
 384     assert(klass == target_method()->method_holder(), "caller resp.");
 385     // Initialize the method's vtable index to "nonvirtual".
 386     // If we allocate a vtable entry, we will update it to a non-negative number.
 387     target_method()->set_vtable_index(Method::nonvirtual_vtable_index);
 388   }
 389 
 390   // Static and <init> methods are never in
 391   if (target_method()->is_static() || target_method()->name() ==  vmSymbols::object_initializer_name()) {
 392     return false;
 393   }
 394 
 395   if (target_method->is_final_method(klass->access_flags())) {
 396     // a final method never needs a new entry; final methods can be statically
 397     // resolved and they have to be present in the vtable only if they override
 398     // a super's method, in which case they re-use its entry
 399     allocate_new = false;
 400   } else if (klass->is_interface()) {
 401     allocate_new = false;  // see note below in needs_new_vtable_entry
 402     // An interface never allocates new vtable slots, only inherits old ones.
 403     // This method will either be assigned its own itable index later,
 404     // or be assigned an inherited vtable index in the loop below.
 405     // default methods inherited by classes store their vtable indices
 406     // in the inheritor's default_vtable_indices.
 407     // default methods inherited by interfaces may already have a
 408     // valid itable index, if so, don't change it.
 409     // Overpass methods in an interface will be assigned an itable index later
 410     // by an inheriting class.
 411     // Private interface methods have no itable index and are always invoked nonvirtually,
 412     // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound()
 413     // will return true.
 414     if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) {
 415       target_method()->set_vtable_index(Method::pending_itable_index);
 416     }
 417   }
 418 
 419   // we need a new entry if there is no superclass
 420   Klass* super = klass->super();
 421   if (super == NULL) {
 422     return allocate_new;
 423   }
 424 
 425   // private methods in classes always have a new entry in the vtable
 426   // specification interpretation since classic has
 427   // private methods not overriding
 428   // JDK8 adds private methods in interfaces which require invokespecial
 429   if (target_method()->is_private()) {
 430     return allocate_new;
 431   }
 432 
 433   // search through the vtable and update overridden entries
 434   // Since check_signature_loaders acquires SystemDictionary_lock
 435   // which can block for gc, once we are in this loop, use handles
 436   // For classfiles built with >= jdk7, we now look for transitive overrides
 437 
 438   Symbol* name = target_method()->name();
 439   Symbol* signature = target_method()->signature();
 440 
 441   Klass* target_klass = target_method()->method_holder();
 442   if (target_klass == NULL) {
 443     target_klass = _klass;
 444   }
 445 
 446   Handle target_loader(THREAD, target_klass->class_loader());
 447 
 448   Symbol* target_classname = target_klass->name();
 449   for(int i = 0; i < super_vtable_len; i++) {
 450     Method* super_method;
 451     if (is_preinitialized_vtable()) {
 452       // If this is a shared class, the vtable is already in the final state (fully
 453       // initialized). Need to look at the super's vtable.
 454       klassVtable superVtable = super->vtable();
 455       super_method = superVtable.method_at(i);
 456     } else {
 457       super_method = method_at(i);
 458     }
 459     // Check if method name matches.  Ignore match if klass is an interface and the
 460     // matching method is a non-public java.lang.Object method.  (See JVMS 5.4.3.4)
 461     // This is safe because the method at this slot should never get invoked.
 462     // (TBD: put in a method to throw NoSuchMethodError if this slot is ever used.)
 463     if (super_method->name() == name && super_method->signature() == signature &&
 464         (!_klass->is_interface() ||
 465          !SystemDictionary::is_nonpublic_Object_method(super_method))) {
 466 
 467       // get super_klass for method_holder for the found method
 468       InstanceKlass* super_klass =  super_method->method_holder();
 469 
 470       // Whether the method is being overridden
 471       bool overrides = false;
 472 
 473       // private methods are also never overridden
 474       if (!super_method->is_private() &&
 475           (is_default
 476           || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD))
 477           || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION)
 478           && ((super_klass = find_transitive_override(super_klass,
 479                              target_method, i, target_loader,
 480                              target_classname, THREAD))
 481                              != (InstanceKlass*)NULL)))))
 482         {
 483         // Package private methods always need a new entry to root their own
 484         // overriding. They may also override other methods.
 485         if (!target_method()->is_package_private()) {
 486           allocate_new = false;
 487         }
 488 
 489         // Do not check loader constraints for overpass methods because overpass
 490         // methods are created by the jvm to throw exceptions.
 491         if (checkconstraints && !target_method()->is_overpass()) {
 492           // Override vtable entry if passes loader constraint check
 493           // if loader constraint checking requested
 494           // No need to visit his super, since he and his super
 495           // have already made any needed loader constraints.
 496           // Since loader constraints are transitive, it is enough
 497           // to link to the first super, and we get all the others.
 498           Handle super_loader(THREAD, super_klass->class_loader());
 499 
 500           if (!oopDesc::equals(target_loader(), super_loader())) {
 501             ResourceMark rm(THREAD);
 502             Symbol* failed_type_symbol =
 503               SystemDictionary::check_signature_loaders(signature, target_loader,
 504                                                         super_loader, true,
 505                                                         CHECK_(false));
 506             if (failed_type_symbol != NULL) {
 507               const char* msg = "loader constraint violation for class %s: when selecting "
 508                 "overriding method \"%s\" the class loader (instance of %s) of the "
 509                 "selected method's type %s, and the class loader (instance of %s) for its super "
 510                 "type %s have different Class objects for the type %s used in the signature";
 511               char* curr_class = klass->name()->as_C_string();
 512               char* sig = target_method()->name_and_sig_as_C_string();
 513               const char* loader1 = SystemDictionary::loader_name(target_loader());
 514               char* sel_class = target_klass->name()->as_C_string();
 515               const char* loader2 = SystemDictionary::loader_name(super_loader());
 516               char* super_class = super_klass->name()->as_C_string();
 517               char* failed_type_name = failed_type_symbol->as_C_string();
 518               size_t buflen = strlen(msg) + strlen(curr_class) + strlen(sig) +
 519                 strlen(loader1) + strlen(sel_class) + strlen(loader2) +
 520                 strlen(super_class) + strlen(failed_type_name);
 521               char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
 522               jio_snprintf(buf, buflen, msg, curr_class, sig, loader1, sel_class, loader2,
 523                            super_class, failed_type_name);
 524               THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false);
 525             }
 526           }
 527         }
 528 
 529         put_method_at(target_method(), i);
 530         overrides = true;
 531         if (!is_default) {
 532           target_method()->set_vtable_index(i);
 533         } else {
 534           if (def_vtable_indices != NULL) {
 535             if (is_preinitialized_vtable()) {
 536               // At runtime initialize_vtable is rerun as part of link_class_impl()
 537               // for a shared class loaded by the non-boot loader.
 538               // The dumptime vtable index should be the same as the runtime index.
 539               assert(def_vtable_indices->at(default_index) == i,
 540                      "dump time vtable index is different from runtime index");
 541             } else {
 542               def_vtable_indices->at_put(default_index, i);
 543             }
 544           }
 545           assert(super_method->is_default_method() || super_method->is_overpass()
 546                  || super_method->is_abstract(), "default override error");
 547         }
 548       } else {
 549         overrides = false;
 550       }
 551       log_vtables(i, overrides, target_method, target_klass, super_method, THREAD);
 552     }
 553   }
 554   return allocate_new;
 555 }
 556 
 557 void klassVtable::put_method_at(Method* m, int index) {
 558   if (is_preinitialized_vtable()) {
 559     // At runtime initialize_vtable is rerun as part of link_class_impl()
 560     // for shared class loaded by the non-boot loader to obtain the loader
 561     // constraints based on the runtime classloaders' context. The dumptime
 562     // method at the vtable index should be the same as the runtime method.
 563     assert(table()[index].method() == m,
 564            "archived method is different from the runtime method");
 565   } else {
 566     if (log_develop_is_enabled(Trace, vtables)) {
 567       ResourceMark rm;
 568       LogTarget(Trace, vtables) lt;
 569       LogStream ls(lt);
 570       const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
 571       ls.print("adding %s at index %d, flags: ", sig, index);
 572       if (m != NULL) {
 573         m->print_linkage_flags(&ls);
 574       }
 575       ls.cr();
 576     }
 577     table()[index].set(m);
 578   }
 579 }
 580 
 581 // Find out if a method "m" with superclass "super", loader "classloader" and
 582 // name "classname" needs a new vtable entry.  Let P be a class package defined
 583 // by "classloader" and "classname".
 584 // NOTE: The logic used here is very similar to the one used for computing
 585 // the vtables indices for a method. We cannot directly use that function because,
 586 // we allocate the InstanceKlass at load time, and that requires that the
 587 // superclass has been loaded.
 588 // However, the vtable entries are filled in at link time, and therefore
 589 // the superclass' vtable may not yet have been filled in.
 590 bool klassVtable::needs_new_vtable_entry(const methodHandle& target_method,
 591                                          const Klass* super,
 592                                          Handle classloader,
 593                                          Symbol* classname,
 594                                          AccessFlags class_flags,
 595                                          u2 major_version,
 596                                          TRAPS) {
 597   if (class_flags.is_interface()) {
 598     // Interfaces do not use vtables, except for java.lang.Object methods,
 599     // so there is no point to assigning
 600     // a vtable index to any of their local methods.  If we refrain from doing this,
 601     // we can use Method::_vtable_index to hold the itable index
 602     return false;
 603   }
 604 
 605   if (target_method->is_final_method(class_flags) ||
 606       // a final method never needs a new entry; final methods can be statically
 607       // resolved and they have to be present in the vtable only if they override
 608       // a super's method, in which case they re-use its entry
 609       (target_method()->is_static()) ||
 610       // static methods don't need to be in vtable
 611       (target_method()->name() ==  vmSymbols::object_initializer_name())
 612       // <init> is never called dynamically-bound
 613       ) {
 614     return false;
 615   }
 616 
 617   // Concrete interface methods do not need new entries, they override
 618   // abstract method entries using default inheritance rules
 619   if (target_method()->method_holder() != NULL &&
 620       target_method()->method_holder()->is_interface()  &&
 621       !target_method()->is_abstract()) {
 622     assert(target_method()->is_default_method() || target_method()->is_private(),
 623            "unexpected interface method type");
 624     return false;
 625   }
 626 
 627   // we need a new entry if there is no superclass
 628   if (super == NULL) {
 629     return true;
 630   }
 631 
 632   // private methods in classes always have a new entry in the vtable.
 633   // Specification interpretation since classic has private methods not overriding.
 634   if (target_method()->is_private()) {
 635     return true;
 636   }
 637 
 638   // Package private methods always need a new entry to root their own
 639   // overriding. This allows transitive overriding to work.
 640   if (target_method()->is_package_private()) {
 641     return true;
 642   }
 643 
 644   // search through the super class hierarchy to see if we need
 645   // a new entry
 646   ResourceMark rm;
 647   Symbol* name = target_method()->name();
 648   Symbol* signature = target_method()->signature();
 649   const Klass* k = super;
 650   Method* super_method = NULL;
 651   InstanceKlass *holder = NULL;
 652   Method* recheck_method =  NULL;
 653   while (k != NULL) {
 654     // lookup through the hierarchy for a method with matching name and sign.
 655     super_method = InstanceKlass::cast(k)->lookup_method(name, signature);
 656     if (super_method == NULL) {
 657       break; // we still have to search for a matching miranda method
 658     }
 659     // get the class holding the matching method
 660     // make sure you use that class for is_override
 661     InstanceKlass* superk = super_method->method_holder();
 662     // we want only instance method matches
 663     // pretend private methods are not in the super vtable
 664     // since we do override around them: e.g. a.m pub/b.m private/c.m pub,
 665     // ignore private, c.m pub does override a.m pub
 666     // For classes that were not javac'd together, we also do transitive overriding around
 667     // methods that have less accessibility
 668     if ((!super_method->is_static()) &&
 669        (!super_method->is_private())) {
 670       if (superk->is_override(super_method, classloader, classname, THREAD)) {
 671         return false;
 672       // else keep looking for transitive overrides
 673       }
 674     }
 675 
 676     // Start with lookup result and continue to search up, for versions supporting transitive override
 677     if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) {
 678       k = superk->super(); // haven't found an override match yet; continue to look
 679     } else {
 680       break;
 681     }
 682   }
 683 
 684   // if the target method is public or protected it may have a matching
 685   // miranda method in the super, whose entry it should re-use.
 686   // Actually, to handle cases that javac would not generate, we need
 687   // this check for all access permissions.
 688   const InstanceKlass *sk = InstanceKlass::cast(super);
 689   if (sk->has_miranda_methods()) {
 690     if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) {
 691       return false;  // found a matching miranda; we do not need a new entry
 692     }
 693   }
 694   return true; // found no match; we need a new entry
 695 }
 696 
 697 // Support for miranda methods
 698 
 699 // get the vtable index of a miranda method with matching "name" and "signature"
 700 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) {
 701   // search from the bottom, might be faster
 702   for (int i = (length() - 1); i >= 0; i--) {
 703     Method* m = table()[i].method();
 704     if (is_miranda_entry_at(i) &&
 705         m->name() == name && m->signature() == signature) {
 706       return i;
 707     }
 708   }
 709   return Method::invalid_vtable_index;
 710 }
 711 
 712 // check if an entry at an index is miranda
 713 // requires that method m at entry be declared ("held") by an interface.
 714 bool klassVtable::is_miranda_entry_at(int i) {
 715   Method* m = method_at(i);
 716   Klass* method_holder = m->method_holder();
 717   InstanceKlass *mhk = InstanceKlass::cast(method_holder);
 718 
 719   // miranda methods are public abstract instance interface methods in a class's vtable
 720   if (mhk->is_interface()) {
 721     assert(m->is_public(), "should be public");
 722     assert(ik()->implements_interface(method_holder) , "this class should implement the interface");
 723     if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super(), klass()->is_interface())) {
 724       return true;
 725     }
 726   }
 727   return false;
 728 }
 729 
 730 // Check if a method is a miranda method, given a class's methods array,
 731 // its default_method table and its super class.
 732 // "Miranda" means an abstract non-private method that would not be
 733 // overridden for the local class.
 734 // A "miranda" method should only include non-private interface
 735 // instance methods, i.e. not private methods, not static methods,
 736 // not default methods (concrete interface methods), not overpass methods.
 737 // If a given class already has a local (including overpass) method, a
 738 // default method, or any of its superclasses has the same which would have
 739 // overridden an abstract method, then this is not a miranda method.
 740 //
 741 // Miranda methods are checked multiple times.
 742 // Pass 1: during class load/class file parsing: before vtable size calculation:
 743 // include superinterface abstract and default methods (non-private instance).
 744 // We include potential default methods to give them space in the vtable.
 745 // During the first run, the current instanceKlass has not yet been
 746 // created, the superclasses and superinterfaces do have instanceKlasses
 747 // but may not have vtables, the default_methods list is empty, no overpasses.
 748 // Default method generation uses the all_mirandas array as the starter set for
 749 // maximally-specific default method calculation.  So, for both classes and
 750 // interfaces, it is necessary that the first pass will find all non-private
 751 // interface instance methods, whether or not they are concrete.
 752 //
 753 // Pass 2: recalculated during vtable initialization: only include abstract methods.
 754 // The goal of pass 2 is to walk through the superinterfaces to see if any of
 755 // the superinterface methods (which were all abstract pre-default methods)
 756 // need to be added to the vtable.
 757 // With the addition of default methods, we have three new challenges:
 758 // overpasses, static interface methods and private interface methods.
 759 // Static and private interface methods do not get added to the vtable and
 760 // are not seen by the method resolution process, so we skip those.
 761 // Overpass methods are already in the vtable, so vtable lookup will
 762 // find them and we don't need to add a miranda method to the end of
 763 // the vtable. So we look for overpass methods and if they are found we
 764 // return false. Note that we inherit our superclasses vtable, so
 765 // the superclass' search also needs to use find_overpass so that if
 766 // one is found we return false.
 767 // False means - we don't need a miranda method added to the vtable.
 768 //
 769 // During the second run, default_methods is set up, so concrete methods from
 770 // superinterfaces with matching names/signatures to default_methods are already
 771 // in the default_methods list and do not need to be appended to the vtable
 772 // as mirandas. Abstract methods may already have been handled via
 773 // overpasses - either local or superclass overpasses, which may be
 774 // in the vtable already.
 775 //
 776 // Pass 3: They are also checked by link resolution and selection,
 777 // for invocation on a method (not interface method) reference that
 778 // resolves to a method with an interface as its method_holder.
 779 // Used as part of walking from the bottom of the vtable to find
 780 // the vtable index for the miranda method.
 781 //
 782 // Part of the Miranda Rights in the US mean that if you do not have
 783 // an attorney one will be appointed for you.
 784 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods,
 785                              Array<Method*>* default_methods, const Klass* super,
 786                              bool is_interface) {
 787   if (m->is_static() || m->is_private() || m->is_overpass()) {
 788     return false;
 789   }
 790   Symbol* name = m->name();
 791   Symbol* signature = m->signature();
 792 
 793   // First look in local methods to see if already covered
 794   if (InstanceKlass::find_local_method(class_methods, name, signature,
 795               Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL)
 796   {
 797     return false;
 798   }
 799 
 800   // Check local default methods
 801   if ((default_methods != NULL) &&
 802     (InstanceKlass::find_method(default_methods, name, signature) != NULL))
 803    {
 804      return false;
 805    }
 806 
 807   // Iterate on all superclasses, which should be InstanceKlasses.
 808   // Note that we explicitly look for overpasses at each level.
 809   // Overpasses may or may not exist for supers for pass 1,
 810   // they should have been created for pass 2 and later.
 811 
 812   for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super())
 813   {
 814      Method* found_mth = InstanceKlass::cast(cursuper)->find_local_method(name, signature,
 815        Klass::find_overpass, Klass::skip_static, Klass::skip_private);
 816      // Ignore non-public methods in java.lang.Object if klass is an interface.
 817      if (found_mth != NULL && (!is_interface ||
 818          !SystemDictionary::is_nonpublic_Object_method(found_mth))) {
 819        return false;
 820      }
 821   }
 822 
 823   return true;
 824 }
 825 
 826 // Scans current_interface_methods for miranda methods that do not
 827 // already appear in new_mirandas, or default methods,  and are also not defined-and-non-private
 828 // in super (superclass).  These mirandas are added to all_mirandas if it is
 829 // not null; in addition, those that are not duplicates of miranda methods
 830 // inherited by super from its interfaces are added to new_mirandas.
 831 // Thus, new_mirandas will be the set of mirandas that this class introduces,
 832 // all_mirandas will be the set of all mirandas applicable to this class
 833 // including all defined in superclasses.
 834 void klassVtable::add_new_mirandas_to_lists(
 835     GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas,
 836     Array<Method*>* current_interface_methods, Array<Method*>* class_methods,
 837     Array<Method*>* default_methods, const Klass* super, bool is_interface) {
 838 
 839   // iterate thru the current interface's method to see if it a miranda
 840   int num_methods = current_interface_methods->length();
 841   for (int i = 0; i < num_methods; i++) {
 842     Method* im = current_interface_methods->at(i);
 843     bool is_duplicate = false;
 844     int num_of_current_mirandas = new_mirandas->length();
 845     // check for duplicate mirandas in different interfaces we implement
 846     for (int j = 0; j < num_of_current_mirandas; j++) {
 847       Method* miranda = new_mirandas->at(j);
 848       if ((im->name() == miranda->name()) &&
 849           (im->signature() == miranda->signature())) {
 850         is_duplicate = true;
 851         break;
 852       }
 853     }
 854 
 855     if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable
 856       if (is_miranda(im, class_methods, default_methods, super, is_interface)) { // is it a miranda at all?
 857         const InstanceKlass *sk = InstanceKlass::cast(super);
 858         // check if it is a duplicate of a super's miranda
 859         if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) {
 860           new_mirandas->append(im);
 861         }
 862         if (all_mirandas != NULL) {
 863           all_mirandas->append(im);
 864         }
 865       }
 866     }
 867   }
 868 }
 869 
 870 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas,
 871                                GrowableArray<Method*>* all_mirandas,
 872                                const Klass* super,
 873                                Array<Method*>* class_methods,
 874                                Array<Method*>* default_methods,
 875                                Array<Klass*>* local_interfaces,
 876                                bool is_interface) {
 877   assert((new_mirandas->length() == 0) , "current mirandas must be 0");
 878 
 879   // iterate thru the local interfaces looking for a miranda
 880   int num_local_ifs = local_interfaces->length();
 881   for (int i = 0; i < num_local_ifs; i++) {
 882     InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i));
 883     add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 884                               ik->methods(), class_methods,
 885                               default_methods, super, is_interface);
 886     // iterate thru each local's super interfaces
 887     Array<Klass*>* super_ifs = ik->transitive_interfaces();
 888     int num_super_ifs = super_ifs->length();
 889     for (int j = 0; j < num_super_ifs; j++) {
 890       InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j));
 891       add_new_mirandas_to_lists(new_mirandas, all_mirandas,
 892                                 sik->methods(), class_methods,
 893                                 default_methods, super, is_interface);
 894     }
 895   }
 896 }
 897 
 898 // Discover miranda methods ("miranda" = "interface abstract, no binding"),
 899 // and append them into the vtable starting at index initialized,
 900 // return the new value of initialized.
 901 // Miranda methods use vtable entries, but do not get assigned a vtable_index
 902 // The vtable_index is discovered by searching from the end of the vtable
 903 int klassVtable::fill_in_mirandas(int initialized) {
 904   GrowableArray<Method*> mirandas(20);
 905   get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(),
 906                ik()->default_methods(), ik()->local_interfaces(),
 907                klass()->is_interface());
 908   for (int i = 0; i < mirandas.length(); i++) {
 909     if (log_develop_is_enabled(Trace, vtables)) {
 910       Method* meth = mirandas.at(i);
 911       ResourceMark rm(Thread::current());
 912       LogTarget(Trace, vtables) lt;
 913       LogStream ls(lt);
 914       if (meth != NULL) {
 915         char* sig = meth->name_and_sig_as_C_string();
 916         ls.print("fill in mirandas with %s index %d, flags: ",
 917                      sig, initialized);
 918         meth->print_linkage_flags(&ls);
 919         ls.cr();
 920       }
 921     }
 922     put_method_at(mirandas.at(i), initialized);
 923     ++initialized;
 924   }
 925   return initialized;
 926 }
 927 
 928 // Copy this class's vtable to the vtable beginning at start.
 929 // Used to copy superclass vtable to prefix of subclass's vtable.
 930 void klassVtable::copy_vtable_to(vtableEntry* start) {
 931   Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size());
 932 }
 933 
 934 #if INCLUDE_JVMTI
 935 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) {
 936   // If old_method is default, find this vtable index in default_vtable_indices
 937   // and replace that method in the _default_methods list
 938   bool updated = false;
 939 
 940   Array<Method*>* default_methods = ik()->default_methods();
 941   if (default_methods != NULL) {
 942     int len = default_methods->length();
 943     for (int idx = 0; idx < len; idx++) {
 944       if (vtable_index == ik()->default_vtable_indices()->at(idx)) {
 945         if (default_methods->at(idx) == old_method) {
 946           default_methods->at_put(idx, new_method);
 947           updated = true;
 948         }
 949         break;
 950       }
 951     }
 952   }
 953   return updated;
 954 }
 955 
 956 // search the vtable for uses of either obsolete or EMCP methods
 957 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
 958   int prn_enabled = 0;
 959   for (int index = 0; index < length(); index++) {
 960     Method* old_method = unchecked_method_at(index);
 961     if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
 962       continue; // skip uninteresting entries
 963     }
 964     assert(!old_method->is_deleted(), "vtable methods may not be deleted");
 965 
 966     Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
 967 
 968     assert(new_method != NULL, "method_with_idnum() should not be NULL");
 969     assert(old_method != new_method, "sanity check");
 970 
 971     put_method_at(new_method, index);
 972     // For default methods, need to update the _default_methods array
 973     // which can only have one method entry for a given signature
 974     bool updated_default = false;
 975     if (old_method->is_default_method()) {
 976       updated_default = adjust_default_method(index, old_method, new_method);
 977     }
 978 
 979     if (log_is_enabled(Info, redefine, class, update)) {
 980       ResourceMark rm;
 981       if (!(*trace_name_printed)) {
 982         log_info(redefine, class, update)
 983           ("adjust: klassname=%s for methods from name=%s",
 984            _klass->external_name(), old_method->method_holder()->external_name());
 985         *trace_name_printed = true;
 986       }
 987       log_debug(redefine, class, update, vtables)
 988         ("vtable method update: %s(%s), updated default = %s",
 989          new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false");
 990     }
 991   }
 992 }
 993 
 994 // a vtable should never contain old or obsolete methods
 995 bool klassVtable::check_no_old_or_obsolete_entries() {
 996   for (int i = 0; i < length(); i++) {
 997     Method* m = unchecked_method_at(i);
 998     if (m != NULL &&
 999         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1000       return false;
1001     }
1002   }
1003   return true;
1004 }
1005 
1006 void klassVtable::dump_vtable() {
1007   tty->print_cr("vtable dump --");
1008   for (int i = 0; i < length(); i++) {
1009     Method* m = unchecked_method_at(i);
1010     if (m != NULL) {
1011       tty->print("      (%5d)  ", i);
1012       m->access_flags().print_on(tty);
1013       if (m->is_default_method()) {
1014         tty->print("default ");
1015       }
1016       if (m->is_overpass()) {
1017         tty->print("overpass");
1018       }
1019       tty->print(" --  ");
1020       m->print_name(tty);
1021       tty->cr();
1022     }
1023   }
1024 }
1025 #endif // INCLUDE_JVMTI
1026 
1027 // CDS/RedefineClasses support - clear vtables so they can be reinitialized
1028 void klassVtable::clear_vtable() {
1029   for (int i = 0; i < _length; i++) table()[i].clear();
1030 }
1031 
1032 bool klassVtable::is_initialized() {
1033   return _length == 0 || table()[0].method() != NULL;
1034 }
1035 
1036 //-----------------------------------------------------------------------------------------
1037 // Itable code
1038 
1039 // Initialize a itableMethodEntry
1040 void itableMethodEntry::initialize(Method* m) {
1041   if (m == NULL) return;
1042 
1043 #ifdef ASSERT
1044   if (MetaspaceShared::is_in_shared_metaspace((void*)&_method) &&
1045      !MetaspaceShared::remapped_readwrite()) {
1046     // At runtime initialize_itable is rerun as part of link_class_impl()
1047     // for a shared class loaded by the non-boot loader.
1048     // The dumptime itable method entry should be the same as the runtime entry.
1049     assert(_method == m, "sanity");
1050   }
1051 #endif
1052   _method = m;
1053 }
1054 
1055 klassItable::klassItable(InstanceKlass* klass) {
1056   _klass = klass;
1057 
1058   if (klass->itable_length() > 0) {
1059     itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable();
1060     if (offset_entry  != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized
1061       // First offset entry points to the first method_entry
1062       intptr_t* method_entry  = (intptr_t *)(((address)klass) + offset_entry->offset());
1063       intptr_t* end         = klass->end_of_itable();
1064 
1065       _table_offset      = (intptr_t*)offset_entry - (intptr_t*)klass;
1066       _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size();
1067       _size_method_table = (end - method_entry)                  / itableMethodEntry::size();
1068       assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation");
1069       return;
1070     }
1071   }
1072 
1073   // The length of the itable was either zero, or it has not yet been initialized.
1074   _table_offset      = 0;
1075   _size_offset_table = 0;
1076   _size_method_table = 0;
1077 }
1078 
1079 static int initialize_count = 0;
1080 
1081 // Initialization
1082 void klassItable::initialize_itable(bool checkconstraints, TRAPS) {
1083   if (_klass->is_interface()) {
1084     // This needs to go after vtable indices are assigned but
1085     // before implementors need to know the number of itable indices.
1086     assign_itable_indices_for_interface(_klass);
1087   }
1088 
1089   // Cannot be setup doing bootstrapping, interfaces don't have
1090   // itables, and klass with only ones entry have empty itables
1091   if (Universe::is_bootstrapping() ||
1092       _klass->is_interface() ||
1093       _klass->itable_length() == itableOffsetEntry::size()) return;
1094 
1095   // There's alway an extra itable entry so we can null-terminate it.
1096   guarantee(size_offset_table() >= 1, "too small");
1097   int num_interfaces = size_offset_table() - 1;
1098   if (num_interfaces > 0) {
1099     log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count,
1100                        _klass->name()->as_C_string());
1101 
1102 
1103     // Iterate through all interfaces
1104     int i;
1105     for(i = 0; i < num_interfaces; i++) {
1106       itableOffsetEntry* ioe = offset_entry(i);
1107       HandleMark hm(THREAD);
1108       Klass* interf = ioe->interface_klass();
1109       assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable");
1110       initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK);
1111     }
1112 
1113   }
1114   // Check that the last entry is empty
1115   itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1);
1116   guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing");
1117 }
1118 
1119 
1120 inline bool interface_method_needs_itable_index(Method* m) {
1121   if (m->is_static())           return false;   // e.g., Stream.empty
1122   if (m->is_initializer())      return false;   // <init> or <clinit>
1123   if (m->is_private())          return false;   // requires invokeSpecial
1124   // If an interface redeclares a method from java.lang.Object,
1125   // it should already have a vtable index, don't touch it.
1126   // e.g., CharSequence.toString (from initialize_vtable)
1127   // if (m->has_vtable_index())  return false; // NO!
1128   return true;
1129 }
1130 
1131 int klassItable::assign_itable_indices_for_interface(Klass* klass) {
1132   // an interface does not have an itable, but its methods need to be numbered
1133   log_develop_debug(itables)("%3d: Initializing itable indices for interface %s",
1134                              ++initialize_count, klass->name()->as_C_string());
1135   Array<Method*>* methods = InstanceKlass::cast(klass)->methods();
1136   int nof_methods = methods->length();
1137   int ime_num = 0;
1138   for (int i = 0; i < nof_methods; i++) {
1139     Method* m = methods->at(i);
1140     if (interface_method_needs_itable_index(m)) {
1141       assert(!m->is_final_method(), "no final interface methods");
1142       // If m is already assigned a vtable index, do not disturb it.
1143       if (log_develop_is_enabled(Trace, itables)) {
1144         ResourceMark rm;
1145         LogTarget(Trace, itables) lt;
1146         LogStream ls(lt);
1147         assert(m != NULL, "methods can never be null");
1148         const char* sig = m->name_and_sig_as_C_string();
1149         if (m->has_vtable_index()) {
1150           ls.print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig);
1151         } else {
1152           ls.print("itable index %d for method: %s, flags: ", ime_num, sig);
1153         }
1154         m->print_linkage_flags(&ls);
1155         ls.cr();
1156       }
1157       if (!m->has_vtable_index()) {
1158         // A shared method could have an initialized itable_index that
1159         // is < 0.
1160         assert(m->vtable_index() == Method::pending_itable_index ||
1161                m->is_shared(),
1162                "set by initialize_vtable");
1163         m->set_itable_index(ime_num);
1164         // Progress to next itable entry
1165         ime_num++;
1166       }
1167     }
1168   }
1169   assert(ime_num == method_count_for_interface(klass), "proper sizing");
1170   return ime_num;
1171 }
1172 
1173 int klassItable::method_count_for_interface(Klass* interf) {
1174   assert(interf->is_instance_klass(), "must be");
1175   assert(interf->is_interface(), "must be");
1176   Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1177   int nof_methods = methods->length();
1178   int length = 0;
1179   while (nof_methods > 0) {
1180     Method* m = methods->at(nof_methods-1);
1181     if (m->has_itable_index()) {
1182       length = m->itable_index() + 1;
1183       break;
1184     }
1185     nof_methods -= 1;
1186   }
1187 #ifdef ASSERT
1188   int nof_methods_copy = nof_methods;
1189   while (nof_methods_copy > 0) {
1190     Method* mm = methods->at(--nof_methods_copy);
1191     assert(!mm->has_itable_index() || mm->itable_index() < length, "");
1192   }
1193 #endif //ASSERT
1194   // return the rightmost itable index, plus one; or 0 if no methods have
1195   // itable indices
1196   return length;
1197 }
1198 
1199 
1200 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) {
1201   Array<Method*>* methods = InstanceKlass::cast(interf)->methods();
1202   int nof_methods = methods->length();
1203   HandleMark hm;
1204   Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader());
1205 
1206   int ime_count = method_count_for_interface(interf);
1207   for (int i = 0; i < nof_methods; i++) {
1208     Method* m = methods->at(i);
1209     methodHandle target;
1210     if (m->has_itable_index()) {
1211       // This search must match the runtime resolution, i.e. selection search for invokeinterface
1212       // to correctly enforce loader constraints for interface method inheritance
1213       target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK);
1214     }
1215     if (target == NULL || !target->is_public() || target->is_abstract() || target->is_overpass()) {
1216       assert(target == NULL || !target->is_overpass() || target->is_public(),
1217              "Non-public overpass method!");
1218       // Entry does not resolve. Leave it empty for AbstractMethodError or other error.
1219       if (!(target == NULL) && !target->is_public()) {
1220         // Stuff an IllegalAccessError throwing method in there instead.
1221         itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()].
1222             initialize(Universe::throw_illegal_access_error());
1223       }
1224     } else {
1225       // Entry did resolve, check loader constraints before initializing
1226       // if checkconstraints requested
1227       if (checkconstraints) {
1228         Handle method_holder_loader (THREAD, target->method_holder()->class_loader());
1229         if (!oopDesc::equals(method_holder_loader(), interface_loader())) {
1230           ResourceMark rm(THREAD);
1231           Symbol* failed_type_symbol =
1232             SystemDictionary::check_signature_loaders(m->signature(),
1233                                                       method_holder_loader,
1234                                                       interface_loader,
1235                                                       true, CHECK);
1236           if (failed_type_symbol != NULL) {
1237             const char* msg = "loader constraint violation in interface itable"
1238               " initialization for class %s: when selecting method \"%s\" the"
1239               " class loader (instance of %s) for super interface %s, and the class"
1240               " loader (instance of %s) of the selected method's type, %s have"
1241               " different Class objects for the type %s used in the signature";
1242             char* current = _klass->name()->as_C_string();
1243             char* sig = m->name_and_sig_as_C_string();
1244             const char* loader1 = SystemDictionary::loader_name(interface_loader());
1245             char* iface = InstanceKlass::cast(interf)->name()->as_C_string();
1246             const char* loader2 = SystemDictionary::loader_name(method_holder_loader());
1247             char* mclass = target()->method_holder()->name()->as_C_string();
1248             char* failed_type_name = failed_type_symbol->as_C_string();
1249             size_t buflen = strlen(msg) + strlen(current) + strlen(sig) +
1250               strlen(loader1) + strlen(iface) + strlen(loader2) + strlen(mclass) +
1251               strlen(failed_type_name);
1252             char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1253             jio_snprintf(buf, buflen, msg, current, sig, loader1, iface,
1254                          loader2, mclass, failed_type_name);
1255             THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1256           }
1257         }
1258       }
1259 
1260       // ime may have moved during GC so recalculate address
1261       int ime_num = m->itable_index();
1262       assert(ime_num < ime_count, "oob");
1263       itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target());
1264       if (log_develop_is_enabled(Trace, itables)) {
1265         ResourceMark rm(THREAD);
1266         if (target() != NULL) {
1267           LogTarget(Trace, itables) lt;
1268           LogStream ls(lt);
1269           char* sig = target()->name_and_sig_as_C_string();
1270           ls.print("interface: %s, ime_num: %d, target: %s, method_holder: %s ",
1271                        interf->internal_name(), ime_num, sig,
1272                        target()->method_holder()->internal_name());
1273           ls.print("target_method flags: ");
1274           target()->print_linkage_flags(&ls);
1275           ls.cr();
1276         }
1277       }
1278     }
1279   }
1280 }
1281 
1282 #if INCLUDE_JVMTI
1283 // search the itable for uses of either obsolete or EMCP methods
1284 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) {
1285 
1286   itableMethodEntry* ime = method_entry(0);
1287   for (int i = 0; i < _size_method_table; i++, ime++) {
1288     Method* old_method = ime->method();
1289     if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) {
1290       continue; // skip uninteresting entries
1291     }
1292     assert(!old_method->is_deleted(), "itable methods may not be deleted");
1293 
1294     Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());
1295 
1296     assert(new_method != NULL, "method_with_idnum() should not be NULL");
1297     assert(old_method != new_method, "sanity check");
1298 
1299     ime->initialize(new_method);
1300 
1301     if (log_is_enabled(Info, redefine, class, update)) {
1302       ResourceMark rm;
1303       if (!(*trace_name_printed)) {
1304         log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
1305         *trace_name_printed = true;
1306       }
1307       log_trace(redefine, class, update, itables)
1308         ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string());
1309     }
1310   }
1311 }
1312 
1313 // an itable should never contain old or obsolete methods
1314 bool klassItable::check_no_old_or_obsolete_entries() {
1315   itableMethodEntry* ime = method_entry(0);
1316   for (int i = 0; i < _size_method_table; i++) {
1317     Method* m = ime->method();
1318     if (m != NULL &&
1319         (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) {
1320       return false;
1321     }
1322     ime++;
1323   }
1324   return true;
1325 }
1326 
1327 void klassItable::dump_itable() {
1328   itableMethodEntry* ime = method_entry(0);
1329   tty->print_cr("itable dump --");
1330   for (int i = 0; i < _size_method_table; i++) {
1331     Method* m = ime->method();
1332     if (m != NULL) {
1333       tty->print("      (%5d)  ", i);
1334       m->access_flags().print_on(tty);
1335       if (m->is_default_method()) {
1336         tty->print("default ");
1337       }
1338       tty->print(" --  ");
1339       m->print_name(tty);
1340       tty->cr();
1341     }
1342     ime++;
1343   }
1344 }
1345 #endif // INCLUDE_JVMTI
1346 
1347 // Setup
1348 class InterfaceVisiterClosure : public StackObj {
1349  public:
1350   virtual void doit(Klass* intf, int method_count) = 0;
1351 };
1352 
1353 // Visit all interfaces with at least one itable method
1354 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) {
1355   // Handle array argument
1356   for(int i = 0; i < transitive_intf->length(); i++) {
1357     Klass* intf = transitive_intf->at(i);
1358     assert(intf->is_interface(), "sanity check");
1359 
1360     // Find no. of itable methods
1361     int method_count = 0;
1362     // method_count = klassItable::method_count_for_interface(intf);
1363     Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1364     if (methods->length() > 0) {
1365       for (int i = methods->length(); --i >= 0; ) {
1366         if (interface_method_needs_itable_index(methods->at(i))) {
1367           method_count++;
1368         }
1369       }
1370     }
1371 
1372     // Visit all interfaces which either have any methods or can participate in receiver type check.
1373     // We do not bother to count methods in transitive interfaces, although that would allow us to skip
1374     // this step in the rare case of a zero-method interface extending another zero-method interface.
1375     if (method_count > 0 || InstanceKlass::cast(intf)->transitive_interfaces()->length() > 0) {
1376       blk->doit(intf, method_count);
1377     }
1378   }
1379 }
1380 
1381 class CountInterfacesClosure : public InterfaceVisiterClosure {
1382  private:
1383   int _nof_methods;
1384   int _nof_interfaces;
1385  public:
1386    CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; }
1387 
1388    int nof_methods() const    { return _nof_methods; }
1389    int nof_interfaces() const { return _nof_interfaces; }
1390 
1391    void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; }
1392 };
1393 
1394 class SetupItableClosure : public InterfaceVisiterClosure  {
1395  private:
1396   itableOffsetEntry* _offset_entry;
1397   itableMethodEntry* _method_entry;
1398   address            _klass_begin;
1399  public:
1400   SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) {
1401     _klass_begin  = klass_begin;
1402     _offset_entry = offset_entry;
1403     _method_entry = method_entry;
1404   }
1405 
1406   itableMethodEntry* method_entry() const { return _method_entry; }
1407 
1408   void doit(Klass* intf, int method_count) {
1409     int offset = ((address)_method_entry) - _klass_begin;
1410     _offset_entry->initialize(intf, offset);
1411     _offset_entry++;
1412     _method_entry += method_count;
1413   }
1414 };
1415 
1416 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) {
1417   // Count no of interfaces and total number of interface methods
1418   CountInterfacesClosure cic;
1419   visit_all_interfaces(transitive_interfaces, &cic);
1420 
1421   // There's alway an extra itable entry so we can null-terminate it.
1422   int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods());
1423 
1424   // Statistics
1425   update_stats(itable_size * wordSize);
1426 
1427   return itable_size;
1428 }
1429 
1430 
1431 // Fill out offset table and interface klasses into the itable space
1432 void klassItable::setup_itable_offset_table(InstanceKlass* klass) {
1433   if (klass->itable_length() == 0) return;
1434   assert(!klass->is_interface(), "Should have zero length itable");
1435 
1436   // Count no of interfaces and total number of interface methods
1437   CountInterfacesClosure cic;
1438   visit_all_interfaces(klass->transitive_interfaces(), &cic);
1439   int nof_methods    = cic.nof_methods();
1440   int nof_interfaces = cic.nof_interfaces();
1441 
1442   // Add one extra entry so we can null-terminate the table
1443   nof_interfaces++;
1444 
1445   assert(compute_itable_size(klass->transitive_interfaces()) ==
1446          calc_itable_size(nof_interfaces, nof_methods),
1447          "mismatch calculation of itable size");
1448 
1449   // Fill-out offset table
1450   itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable();
1451   itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces);
1452   intptr_t* end               = klass->end_of_itable();
1453   assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)");
1454   assert((oop*)(end) == (oop*)(ime + nof_methods),                      "wrong offset calculation (2)");
1455 
1456   // Visit all interfaces and initialize itable offset table
1457   SetupItableClosure sic((address)klass, ioe, ime);
1458   visit_all_interfaces(klass->transitive_interfaces(), &sic);
1459 
1460 #ifdef ASSERT
1461   ime  = sic.method_entry();
1462   oop* v = (oop*) klass->end_of_itable();
1463   assert( (oop*)(ime) == v, "wrong offset calculation (2)");
1464 #endif
1465 }
1466 
1467 
1468 // inverse to itable_index
1469 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) {
1470   assert(InstanceKlass::cast(intf)->is_interface(), "sanity check");
1471   assert(intf->verify_itable_index(itable_index), "");
1472   Array<Method*>* methods = InstanceKlass::cast(intf)->methods();
1473 
1474   if (itable_index < 0 || itable_index >= method_count_for_interface(intf))
1475     return NULL;                // help caller defend against bad indices
1476 
1477   int index = itable_index;
1478   Method* m = methods->at(index);
1479   int index2 = -1;
1480   while (!m->has_itable_index() ||
1481          (index2 = m->itable_index()) != itable_index) {
1482     assert(index2 < itable_index, "monotonic");
1483     if (++index == methods->length())
1484       return NULL;
1485     m = methods->at(index);
1486   }
1487   assert(m->itable_index() == itable_index, "correct inverse");
1488 
1489   return m;
1490 }
1491 
1492 void klassVtable::verify(outputStream* st, bool forced) {
1493   // make sure table is initialized
1494   if (!Universe::is_fully_initialized()) return;
1495 #ifndef PRODUCT
1496   // avoid redundant verifies
1497   if (!forced && _verify_count == Universe::verify_count()) return;
1498   _verify_count = Universe::verify_count();
1499 #endif
1500   oop* end_of_obj = (oop*)_klass + _klass->size();
1501   oop* end_of_vtable = (oop *)&table()[_length];
1502   if (end_of_vtable > end_of_obj) {
1503     fatal("klass %s: klass object too short (vtable extends beyond end)",
1504           _klass->internal_name());
1505   }
1506 
1507   for (int i = 0; i < _length; i++) table()[i].verify(this, st);
1508   // verify consistency with superKlass vtable
1509   Klass* super = _klass->super();
1510   if (super != NULL) {
1511     InstanceKlass* sk = InstanceKlass::cast(super);
1512     klassVtable vt = sk->vtable();
1513     for (int i = 0; i < vt.length(); i++) {
1514       verify_against(st, &vt, i);
1515     }
1516   }
1517 }
1518 
1519 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
1520   vtableEntry* vte = &vt->table()[index];
1521   if (vte->method()->name()      != table()[index].method()->name() ||
1522       vte->method()->signature() != table()[index].method()->signature()) {
1523     fatal("mismatched name/signature of vtable entries");
1524   }
1525 }
1526 
1527 #ifndef PRODUCT
1528 void klassVtable::print() {
1529   ResourceMark rm;
1530   tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length());
1531   for (int i = 0; i < length(); i++) {
1532     table()[i].print();
1533     tty->cr();
1534   }
1535 }
1536 #endif
1537 
1538 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
1539   NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
1540   Klass* vtklass = vt->klass();
1541   if (vtklass->is_instance_klass() &&
1542      (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) {
1543     assert(method() != NULL, "must have set method");
1544   }
1545   if (method() != NULL) {
1546     method()->verify();
1547     // we sub_type, because it could be a miranda method
1548     if (!vtklass->is_subtype_of(method()->method_holder())) {
1549 #ifndef PRODUCT
1550       print();
1551 #endif
1552       fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this));
1553     }
1554  }
1555 }
1556 
1557 #ifndef PRODUCT
1558 
1559 void vtableEntry::print() {
1560   ResourceMark rm;
1561   tty->print("vtableEntry %s: ", method()->name()->as_C_string());
1562   if (Verbose) {
1563     tty->print("m " PTR_FORMAT " ", p2i(method()));
1564   }
1565 }
1566 
1567 class VtableStats : AllStatic {
1568  public:
1569   static int no_klasses;                // # classes with vtables
1570   static int no_array_klasses;          // # array classes
1571   static int no_instance_klasses;       // # instanceKlasses
1572   static int sum_of_vtable_len;         // total # of vtable entries
1573   static int sum_of_array_vtable_len;   // total # of vtable entries in array klasses only
1574   static int fixed;                     // total fixed overhead in bytes
1575   static int filler;                    // overhead caused by filler bytes
1576   static int entries;                   // total bytes consumed by vtable entries
1577   static int array_entries;             // total bytes consumed by array vtable entries
1578 
1579   static void do_class(Klass* k) {
1580     Klass* kl = k;
1581     klassVtable vt = kl->vtable();
1582     no_klasses++;
1583     if (kl->is_instance_klass()) {
1584       no_instance_klasses++;
1585       kl->array_klasses_do(do_class);
1586     }
1587     if (kl->is_array_klass()) {
1588       no_array_klasses++;
1589       sum_of_array_vtable_len += vt.length();
1590     }
1591     sum_of_vtable_len += vt.length();
1592   }
1593 
1594   static void compute() {
1595     ClassLoaderDataGraph::classes_do(do_class);
1596     fixed  = no_klasses * oopSize;      // vtable length
1597     // filler size is a conservative approximation
1598     filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1);
1599     entries = sizeof(vtableEntry) * sum_of_vtable_len;
1600     array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len;
1601   }
1602 };
1603 
1604 int VtableStats::no_klasses = 0;
1605 int VtableStats::no_array_klasses = 0;
1606 int VtableStats::no_instance_klasses = 0;
1607 int VtableStats::sum_of_vtable_len = 0;
1608 int VtableStats::sum_of_array_vtable_len = 0;
1609 int VtableStats::fixed = 0;
1610 int VtableStats::filler = 0;
1611 int VtableStats::entries = 0;
1612 int VtableStats::array_entries = 0;
1613 
1614 void klassVtable::print_statistics() {
1615   ResourceMark rm;
1616   HandleMark hm;
1617   VtableStats::compute();
1618   tty->print_cr("vtable statistics:");
1619   tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses);
1620   int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries;
1621   tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed);
1622   tty->print_cr("%6d bytes filler overhead", VtableStats::filler);
1623   tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries);
1624   tty->print_cr("%6d bytes total", total);
1625 }
1626 
1627 int  klassItable::_total_classes;   // Total no. of classes with itables
1628 long klassItable::_total_size;      // Total no. of bytes used for itables
1629 
1630 void klassItable::print_statistics() {
1631  tty->print_cr("itable statistics:");
1632  tty->print_cr("%6d classes with itables", _total_classes);
1633  tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes);
1634 }
1635 
1636 #endif // PRODUCT