rev 49271 : 8199852: Print more information about class loaders in LinkageErrors.

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