1 /* 2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "classfile/vmSymbols.hpp" 28 #include "gc/shared/gcLocker.hpp" 29 #include "logging/log.hpp" 30 #include "memory/metaspaceShared.hpp" 31 #include "memory/resourceArea.hpp" 32 #include "memory/universe.inline.hpp" 33 #include "oops/instanceKlass.hpp" 34 #include "oops/klassVtable.hpp" 35 #include "oops/method.hpp" 36 #include "oops/objArrayOop.hpp" 37 #include "oops/oop.inline.hpp" 38 #include "prims/jvm.h" 39 #include "runtime/arguments.hpp" 40 #include "runtime/handles.inline.hpp" 41 #include "utilities/copy.hpp" 42 43 inline InstanceKlass* klassVtable::ik() const { 44 return InstanceKlass::cast(_klass); 45 } 46 47 bool klassVtable::is_preinitialized_vtable() { 48 return _klass->is_shared() && !MetaspaceShared::remapped_readwrite(); 49 } 50 51 52 // this function computes the vtable size (including the size needed for miranda 53 // methods) and the number of miranda methods in this class. 54 // Note on Miranda methods: Let's say there is a class C that implements 55 // interface I, and none of C's superclasses implements I. 56 // Let's say there is an abstract method m in I that neither C 57 // nor any of its super classes implement (i.e there is no method of any access, 58 // with the same name and signature as m), then m is a Miranda method which is 59 // entered as a public abstract method in C's vtable. From then on it should 60 // treated as any other public method in C for method over-ride purposes. 61 void klassVtable::compute_vtable_size_and_num_mirandas( 62 int* vtable_length_ret, int* num_new_mirandas, 63 GrowableArray<Method*>* all_mirandas, const Klass* super, 64 Array<Method*>* methods, AccessFlags class_flags, u2 major_version, 65 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces, 66 TRAPS) { 67 NoSafepointVerifier nsv; 68 69 // set up default result values 70 int vtable_length = 0; 71 72 // start off with super's vtable length 73 vtable_length = super == NULL ? 0 : super->vtable_length(); 74 75 // go thru each method in the methods table to see if it needs a new entry 76 int len = methods->length(); 77 for (int i = 0; i < len; i++) { 78 assert(methods->at(i)->is_method(), "must be a Method*"); 79 methodHandle mh(THREAD, methods->at(i)); 80 81 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, major_version, THREAD)) { 82 vtable_length += vtableEntry::size(); // we need a new entry 83 } 84 } 85 86 GrowableArray<Method*> new_mirandas(20); 87 // compute the number of mirandas methods that must be added to the end 88 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces); 89 *num_new_mirandas = new_mirandas.length(); 90 91 // Interfaces do not need interface methods in their vtables 92 // This includes miranda methods and during later processing, default methods 93 if (!class_flags.is_interface()) { 94 vtable_length += *num_new_mirandas * vtableEntry::size(); 95 } 96 97 if (Universe::is_bootstrapping() && vtable_length == 0) { 98 // array classes don't have their superclass set correctly during 99 // bootstrapping 100 vtable_length = Universe::base_vtable_size(); 101 } 102 103 if (super == NULL && vtable_length != Universe::base_vtable_size()) { 104 if (Universe::is_bootstrapping()) { 105 // Someone is attempting to override java.lang.Object incorrectly on the 106 // bootclasspath. The JVM cannot recover from this error including throwing 107 // an exception 108 vm_exit_during_initialization("Incompatible definition of java.lang.Object"); 109 } else { 110 // Someone is attempting to redefine java.lang.Object incorrectly. The 111 // only way this should happen is from 112 // SystemDictionary::resolve_from_stream(), which will detect this later 113 // and throw a security exception. So don't assert here to let 114 // the exception occur. 115 vtable_length = Universe::base_vtable_size(); 116 } 117 } 118 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 119 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 120 121 *vtable_length_ret = vtable_length; 122 } 123 124 int klassVtable::index_of(Method* m, int len) const { 125 assert(m->has_vtable_index(), "do not ask this of non-vtable methods"); 126 return m->vtable_index(); 127 } 128 129 // Copy super class's vtable to the first part (prefix) of this class's vtable, 130 // and return the number of entries copied. Expects that 'super' is the Java 131 // super class (arrays can have "array" super classes that must be skipped). 132 int klassVtable::initialize_from_super(Klass* super) { 133 if (super == NULL) { 134 return 0; 135 } else if (is_preinitialized_vtable()) { 136 // A shared class' vtable is preinitialized at dump time. No need to copy 137 // methods from super class for shared class, as that was already done 138 // during archiving time. However, if Jvmti has redefined a class, 139 // copy super class's vtable in case the super class has changed. 140 return super->vtable().length(); 141 } else { 142 // copy methods from superKlass 143 klassVtable superVtable = super->vtable(); 144 assert(superVtable.length() <= _length, "vtable too short"); 145 #ifdef ASSERT 146 superVtable.verify(tty, true); 147 #endif 148 superVtable.copy_vtable_to(table()); 149 if (log_develop_is_enabled(Trace, vtables)) { 150 ResourceMark rm; 151 log_develop_trace(vtables)("copy vtable from %s to %s size %d", 152 super->internal_name(), klass()->internal_name(), 153 _length); 154 } 155 return superVtable.length(); 156 } 157 } 158 159 // 160 // Revised lookup semantics introduced 1.3 (Kestrel beta) 161 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { 162 163 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 164 Klass* super = _klass->java_super(); 165 int nofNewEntries = 0; 166 167 bool is_shared = _klass->is_shared(); 168 169 if (!_klass->is_array_klass()) { 170 ResourceMark rm(THREAD); 171 log_develop_debug(vtables)("Initializing: %s", _klass->name()->as_C_string()); 172 } 173 174 #ifdef ASSERT 175 oop* end_of_obj = (oop*)_klass + _klass->size(); 176 oop* end_of_vtable = (oop*)&table()[_length]; 177 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 178 #endif 179 180 if (Universe::is_bootstrapping()) { 181 assert(!is_shared, "sanity"); 182 // just clear everything 183 for (int i = 0; i < _length; i++) table()[i].clear(); 184 return; 185 } 186 187 int super_vtable_len = initialize_from_super(super); 188 if (_klass->is_array_klass()) { 189 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 190 } else { 191 assert(_klass->is_instance_klass(), "must be InstanceKlass"); 192 193 Array<Method*>* methods = ik()->methods(); 194 int len = methods->length(); 195 int initialized = super_vtable_len; 196 197 // Check each of this class's methods against super; 198 // if override, replace in copy of super vtable, otherwise append to end 199 for (int i = 0; i < len; i++) { 200 // update_inherited_vtable can stop for gc - ensure using handles 201 HandleMark hm(THREAD); 202 assert(methods->at(i)->is_method(), "must be a Method*"); 203 methodHandle mh(THREAD, methods->at(i)); 204 205 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK); 206 207 if (needs_new_entry) { 208 put_method_at(mh(), initialized); 209 mh()->set_vtable_index(initialized); // set primary vtable index 210 initialized++; 211 } 212 } 213 214 // update vtable with default_methods 215 Array<Method*>* default_methods = ik()->default_methods(); 216 if (default_methods != NULL) { 217 len = default_methods->length(); 218 if (len > 0) { 219 Array<int>* def_vtable_indices = NULL; 220 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) { 221 assert(!is_shared, "shared class def_vtable_indices does not exist"); 222 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK); 223 } else { 224 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 225 } 226 for (int i = 0; i < len; i++) { 227 HandleMark hm(THREAD); 228 assert(default_methods->at(i)->is_method(), "must be a Method*"); 229 methodHandle mh(THREAD, default_methods->at(i)); 230 assert(!mh->is_private(), "private interface method in the default method list"); 231 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK); 232 233 // needs new entry 234 if (needs_new_entry) { 235 put_method_at(mh(), initialized); 236 if (is_preinitialized_vtable()) { 237 // At runtime initialize_vtable is rerun for a shared class 238 // (loaded by the non-boot loader) as part of link_class_impl(). 239 // The dumptime vtable index should be the same as the runtime index. 240 assert(def_vtable_indices->at(i) == initialized, 241 "dump time vtable index is different from runtime index"); 242 } else { 243 def_vtable_indices->at_put(i, initialized); //set vtable index 244 } 245 initialized++; 246 } 247 } 248 } 249 } 250 251 // add miranda methods; it will also return the updated initialized 252 // Interfaces do not need interface methods in their vtables 253 // This includes miranda methods and during later processing, default methods 254 if (!ik()->is_interface()) { 255 initialized = fill_in_mirandas(initialized); 256 } 257 258 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 259 // package_private -> public/protected), the vtable might actually be smaller than our initial 260 // calculation, for classfile versions for which we do not do transitive override 261 // calculations. 262 if (ik()->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 263 assert(initialized == _length, "vtable initialization failed"); 264 } else { 265 assert(initialized <= _length, "vtable initialization failed"); 266 for(;initialized < _length; initialized++) { 267 table()[initialized].clear(); 268 } 269 } 270 NOT_PRODUCT(verify(tty, true)); 271 } 272 } 273 274 // Called for cases where a method does not override its superclass' vtable entry 275 // For bytecodes not produced by javac together it is possible that a method does not override 276 // the superclass's method, but might indirectly override a super-super class's vtable entry 277 // If none found, return a null superk, else return the superk of the method this does override 278 // For public and protected methods: if they override a superclass, they will 279 // also be overridden themselves appropriately. 280 // Private methods do not override and are not overridden. 281 // Package Private methods are trickier: 282 // e.g. P1.A, pub m 283 // P2.B extends A, package private m 284 // P1.C extends B, public m 285 // P1.C.m needs to override P1.A.m and can not override P2.B.m 286 // Therefore: all package private methods need their own vtable entries for 287 // them to be the root of an inheritance overriding decision 288 // Package private methods may also override other vtable entries 289 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, 290 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 291 InstanceKlass* superk = initialsuper; 292 while (superk != NULL && superk->super() != NULL) { 293 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 294 klassVtable ssVtable = supersuperklass->vtable(); 295 if (vtable_index < ssVtable.length()) { 296 Method* super_method = ssVtable.method_at(vtable_index); 297 #ifndef PRODUCT 298 Symbol* name= target_method()->name(); 299 Symbol* signature = target_method()->signature(); 300 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 301 #endif 302 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 303 if (log_develop_is_enabled(Trace, vtables)) { 304 ResourceMark rm(THREAD); 305 outputStream* logst = Log(vtables)::trace_stream(); 306 char* sig = target_method()->name_and_sig_as_C_string(); 307 logst->print("transitive overriding superclass %s with %s index %d, original flags: ", 308 supersuperklass->internal_name(), 309 sig, vtable_index); 310 super_method->print_linkage_flags(logst); 311 logst->print("overriders flags: "); 312 target_method->print_linkage_flags(logst); 313 logst->cr(); 314 } 315 316 break; // return found superk 317 } 318 } else { 319 // super class has no vtable entry here, stop transitive search 320 superk = (InstanceKlass*)NULL; 321 break; 322 } 323 // if no override found yet, continue to search up 324 superk = superk->super() == NULL ? NULL : InstanceKlass::cast(superk->super()); 325 } 326 327 return superk; 328 } 329 330 static void log_vtables(int i, bool overrides, methodHandle target_method, 331 Klass* target_klass, Method* super_method, 332 Thread* thread) { 333 #ifndef PRODUCT 334 if (log_develop_is_enabled(Trace, vtables)) { 335 ResourceMark rm(thread); 336 outputStream* logst = Log(vtables)::trace_stream(); 337 char* sig = target_method()->name_and_sig_as_C_string(); 338 if (overrides) { 339 logst->print("overriding with %s index %d, original flags: ", 340 sig, i); 341 } else { 342 logst->print("NOT overriding with %s index %d, original flags: ", 343 sig, i); 344 } 345 super_method->print_linkage_flags(logst); 346 logst->print("overriders flags: "); 347 target_method->print_linkage_flags(logst); 348 logst->cr(); 349 } 350 #endif 351 } 352 353 // Update child's copy of super vtable for overrides 354 // OR return true if a new vtable entry is required. 355 // Only called for InstanceKlass's, i.e. not for arrays 356 // If that changed, could not use _klass as handle for klass 357 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, 358 int super_vtable_len, int default_index, 359 bool checkconstraints, TRAPS) { 360 ResourceMark rm; 361 bool allocate_new = true; 362 assert(klass->is_instance_klass(), "must be InstanceKlass"); 363 364 Array<int>* def_vtable_indices = NULL; 365 bool is_default = false; 366 367 // default methods are non-private concrete methods in superinterfaces which are added 368 // to the vtable with their real method_holder. 369 // Since vtable and itable indices share the same storage, don't touch 370 // the default method's real vtable/itable index. 371 // default_vtable_indices stores the vtable value relative to this inheritor 372 if (default_index >= 0 ) { 373 is_default = true; 374 def_vtable_indices = klass->default_vtable_indices(); 375 assert(!target_method()->is_private(), "private interface method flagged as default"); 376 assert(def_vtable_indices != NULL, "def vtable alloc?"); 377 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 378 } else { 379 assert(klass == target_method()->method_holder(), "caller resp."); 380 // Initialize the method's vtable index to "nonvirtual". 381 // If we allocate a vtable entry, we will update it to a non-negative number. 382 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 383 } 384 385 // Static and <init> methods are never in 386 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { 387 return false; 388 } 389 390 if (target_method->is_final_method(klass->access_flags())) { 391 // a final method never needs a new entry; final methods can be statically 392 // resolved and they have to be present in the vtable only if they override 393 // a super's method, in which case they re-use its entry 394 allocate_new = false; 395 } else if (klass->is_interface()) { 396 allocate_new = false; // see note below in needs_new_vtable_entry 397 // An interface never allocates new vtable slots, only inherits old ones. 398 // This method will either be assigned its own itable index later, 399 // or be assigned an inherited vtable index in the loop below. 400 // default methods inherited by classes store their vtable indices 401 // in the inheritor's default_vtable_indices. 402 // default methods inherited by interfaces may already have a 403 // valid itable index, if so, don't change it. 404 // Overpass methods in an interface will be assigned an itable index later 405 // by an inheriting class. 406 // Private interface methods have no itable index and are always invoked nonvirtually, 407 // so they retain their nonvirtual_vtable_index value, and therefore can_be_statically_bound() 408 // will return true. 409 if ((!is_default || !target_method()->has_itable_index()) && !target_method()->is_private()) { 410 target_method()->set_vtable_index(Method::pending_itable_index); 411 } 412 } 413 414 // we need a new entry if there is no superclass 415 Klass* super = klass->super(); 416 if (super == NULL) { 417 return allocate_new; 418 } 419 420 // private methods in classes always have a new entry in the vtable 421 // specification interpretation since classic has 422 // private methods not overriding 423 // JDK8 adds private methods in interfaces which require invokespecial 424 if (target_method()->is_private()) { 425 return allocate_new; 426 } 427 428 // search through the vtable and update overridden entries 429 // Since check_signature_loaders acquires SystemDictionary_lock 430 // which can block for gc, once we are in this loop, use handles 431 // For classfiles built with >= jdk7, we now look for transitive overrides 432 433 Symbol* name = target_method()->name(); 434 Symbol* signature = target_method()->signature(); 435 436 Klass* target_klass = target_method()->method_holder(); 437 if (target_klass == NULL) { 438 target_klass = _klass; 439 } 440 441 Handle target_loader(THREAD, target_klass->class_loader()); 442 443 Symbol* target_classname = target_klass->name(); 444 for(int i = 0; i < super_vtable_len; i++) { 445 Method* super_method; 446 if (is_preinitialized_vtable()) { 447 // If this is a shared class, the vtable is already in the final state (fully 448 // initialized). Need to look at the super's vtable. 449 klassVtable superVtable = super->vtable(); 450 super_method = superVtable.method_at(i); 451 } else { 452 super_method = method_at(i); 453 } 454 // Check if method name matches 455 if (super_method->name() == name && super_method->signature() == signature) { 456 457 // get super_klass for method_holder for the found method 458 InstanceKlass* super_klass = super_method->method_holder(); 459 460 // Whether the method is being overridden 461 bool overrides = false; 462 463 // private methods are also never overridden 464 if (!super_method->is_private() && 465 (is_default 466 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) 467 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 468 && ((super_klass = find_transitive_override(super_klass, 469 target_method, i, target_loader, 470 target_classname, THREAD)) 471 != (InstanceKlass*)NULL))))) 472 { 473 // Package private methods always need a new entry to root their own 474 // overriding. They may also override other methods. 475 if (!target_method()->is_package_private()) { 476 allocate_new = false; 477 } 478 479 if (checkconstraints) { 480 // Override vtable entry if passes loader constraint check 481 // if loader constraint checking requested 482 // No need to visit his super, since he and his super 483 // have already made any needed loader constraints. 484 // Since loader constraints are transitive, it is enough 485 // to link to the first super, and we get all the others. 486 Handle super_loader(THREAD, super_klass->class_loader()); 487 488 if (target_loader() != super_loader()) { 489 ResourceMark rm(THREAD); 490 Symbol* failed_type_symbol = 491 SystemDictionary::check_signature_loaders(signature, target_loader, 492 super_loader, true, 493 CHECK_(false)); 494 if (failed_type_symbol != NULL) { 495 const char* msg = "loader constraint violation: when resolving " 496 "overridden method \"%s\" the class loader (instance" 497 " of %s) of the current class, %s, and its superclass loader " 498 "(instance of %s), have different Class objects for the type " 499 "%s used in the signature"; 500 char* sig = target_method()->name_and_sig_as_C_string(); 501 const char* loader1 = SystemDictionary::loader_name(target_loader()); 502 char* current = target_klass->name()->as_C_string(); 503 const char* loader2 = SystemDictionary::loader_name(super_loader()); 504 char* failed_type_name = failed_type_symbol->as_C_string(); 505 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 506 strlen(current) + strlen(loader2) + strlen(failed_type_name); 507 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 508 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 509 failed_type_name); 510 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); 511 } 512 } 513 } 514 515 put_method_at(target_method(), i); 516 overrides = true; 517 if (!is_default) { 518 target_method()->set_vtable_index(i); 519 } else { 520 if (def_vtable_indices != NULL) { 521 if (is_preinitialized_vtable()) { 522 // At runtime initialize_vtable is rerun as part of link_class_impl() 523 // for a shared class loaded by the non-boot loader. 524 // The dumptime vtable index should be the same as the runtime index. 525 assert(def_vtable_indices->at(default_index) == i, 526 "dump time vtable index is different from runtime index"); 527 } else { 528 def_vtable_indices->at_put(default_index, i); 529 } 530 } 531 assert(super_method->is_default_method() || super_method->is_overpass() 532 || super_method->is_abstract(), "default override error"); 533 } 534 } else { 535 overrides = false; 536 } 537 log_vtables(i, overrides, target_method, target_klass, super_method, THREAD); 538 } 539 } 540 return allocate_new; 541 } 542 543 void klassVtable::put_method_at(Method* m, int index) { 544 if (is_preinitialized_vtable()) { 545 // At runtime initialize_vtable is rerun as part of link_class_impl() 546 // for shared class loaded by the non-boot loader to obtain the loader 547 // constraints based on the runtime classloaders' context. The dumptime 548 // method at the vtable index should be the same as the runtime method. 549 assert(table()[index].method() == m, 550 "archived method is different from the runtime method"); 551 } else { 552 if (log_develop_is_enabled(Trace, vtables)) { 553 ResourceMark rm; 554 outputStream* logst = Log(vtables)::trace_stream(); 555 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 556 logst->print("adding %s at index %d, flags: ", sig, index); 557 if (m != NULL) { 558 m->print_linkage_flags(logst); 559 } 560 logst->cr(); 561 } 562 table()[index].set(m); 563 } 564 } 565 566 // Find out if a method "m" with superclass "super", loader "classloader" and 567 // name "classname" needs a new vtable entry. Let P be a class package defined 568 // by "classloader" and "classname". 569 // NOTE: The logic used here is very similar to the one used for computing 570 // the vtables indices for a method. We cannot directly use that function because, 571 // we allocate the InstanceKlass at load time, and that requires that the 572 // superclass has been loaded. 573 // However, the vtable entries are filled in at link time, and therefore 574 // the superclass' vtable may not yet have been filled in. 575 bool klassVtable::needs_new_vtable_entry(methodHandle target_method, 576 const Klass* super, 577 Handle classloader, 578 Symbol* classname, 579 AccessFlags class_flags, 580 u2 major_version, 581 TRAPS) { 582 if (class_flags.is_interface()) { 583 // Interfaces do not use vtables, except for java.lang.Object methods, 584 // so there is no point to assigning 585 // a vtable index to any of their local methods. If we refrain from doing this, 586 // we can use Method::_vtable_index to hold the itable index 587 return false; 588 } 589 590 if (target_method->is_final_method(class_flags) || 591 // a final method never needs a new entry; final methods can be statically 592 // resolved and they have to be present in the vtable only if they override 593 // a super's method, in which case they re-use its entry 594 (target_method()->is_static()) || 595 // static methods don't need to be in vtable 596 (target_method()->name() == vmSymbols::object_initializer_name()) 597 // <init> is never called dynamically-bound 598 ) { 599 return false; 600 } 601 602 // Concrete interface methods do not need new entries, they override 603 // abstract method entries using default inheritance rules 604 if (target_method()->method_holder() != NULL && 605 target_method()->method_holder()->is_interface() && 606 !target_method()->is_abstract()) { 607 assert(target_method()->is_default_method() || target_method()->is_private(), 608 "unexpected interface method type"); 609 return false; 610 } 611 612 // we need a new entry if there is no superclass 613 if (super == NULL) { 614 return true; 615 } 616 617 // private methods in classes always have a new entry in the vtable. 618 // Specification interpretation since classic has private methods not overriding. 619 if (target_method()->is_private()) { 620 return true; 621 } 622 623 // Package private methods always need a new entry to root their own 624 // overriding. This allows transitive overriding to work. 625 if (target_method()->is_package_private()) { 626 return true; 627 } 628 629 // search through the super class hierarchy to see if we need 630 // a new entry 631 ResourceMark rm; 632 Symbol* name = target_method()->name(); 633 Symbol* signature = target_method()->signature(); 634 const Klass* k = super; 635 Method* super_method = NULL; 636 InstanceKlass *holder = NULL; 637 Method* recheck_method = NULL; 638 while (k != NULL) { 639 // lookup through the hierarchy for a method with matching name and sign. 640 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 641 if (super_method == NULL) { 642 break; // we still have to search for a matching miranda method 643 } 644 // get the class holding the matching method 645 // make sure you use that class for is_override 646 InstanceKlass* superk = super_method->method_holder(); 647 // we want only instance method matches 648 // pretend private methods are not in the super vtable 649 // since we do override around them: e.g. a.m pub/b.m private/c.m pub, 650 // ignore private, c.m pub does override a.m pub 651 // For classes that were not javac'd together, we also do transitive overriding around 652 // methods that have less accessibility 653 if ((!super_method->is_static()) && 654 (!super_method->is_private())) { 655 if (superk->is_override(super_method, classloader, classname, THREAD)) { 656 return false; 657 // else keep looking for transitive overrides 658 } 659 } 660 661 // Start with lookup result and continue to search up, for versions supporting transitive override 662 if (major_version >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) { 663 k = superk->super(); // haven't found an override match yet; continue to look 664 } else { 665 break; 666 } 667 } 668 669 // if the target method is public or protected it may have a matching 670 // miranda method in the super, whose entry it should re-use. 671 // Actually, to handle cases that javac would not generate, we need 672 // this check for all access permissions. 673 const InstanceKlass *sk = InstanceKlass::cast(super); 674 if (sk->has_miranda_methods()) { 675 if (sk->lookup_method_in_all_interfaces(name, signature, Klass::find_defaults) != NULL) { 676 return false; // found a matching miranda; we do not need a new entry 677 } 678 } 679 return true; // found no match; we need a new entry 680 } 681 682 // Support for miranda methods 683 684 // get the vtable index of a miranda method with matching "name" and "signature" 685 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 686 // search from the bottom, might be faster 687 for (int i = (length() - 1); i >= 0; i--) { 688 Method* m = table()[i].method(); 689 if (is_miranda_entry_at(i) && 690 m->name() == name && m->signature() == signature) { 691 return i; 692 } 693 } 694 return Method::invalid_vtable_index; 695 } 696 697 // check if an entry at an index is miranda 698 // requires that method m at entry be declared ("held") by an interface. 699 bool klassVtable::is_miranda_entry_at(int i) { 700 Method* m = method_at(i); 701 Klass* method_holder = m->method_holder(); 702 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 703 704 // miranda methods are public abstract instance interface methods in a class's vtable 705 if (mhk->is_interface()) { 706 assert(m->is_public(), "should be public"); 707 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 708 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) { 709 return true; 710 } 711 } 712 return false; 713 } 714 715 // Check if a method is a miranda method, given a class's methods array, 716 // its default_method table and its super class. 717 // "Miranda" means an abstract non-private method that would not be 718 // overridden for the local class. 719 // A "miranda" method should only include non-private interface 720 // instance methods, i.e. not private methods, not static methods, 721 // not default methods (concrete interface methods), not overpass methods. 722 // If a given class already has a local (including overpass) method, a 723 // default method, or any of its superclasses has the same which would have 724 // overridden an abstract method, then this is not a miranda method. 725 // 726 // Miranda methods are checked multiple times. 727 // Pass 1: during class load/class file parsing: before vtable size calculation: 728 // include superinterface abstract and default methods (non-private instance). 729 // We include potential default methods to give them space in the vtable. 730 // During the first run, the current instanceKlass has not yet been 731 // created, the superclasses and superinterfaces do have instanceKlasses 732 // but may not have vtables, the default_methods list is empty, no overpasses. 733 // This is seen by default method creation. 734 // 735 // Pass 2: recalculated during vtable initialization: only include abstract methods. 736 // The goal of pass 2 is to walk through the superinterfaces to see if any of 737 // the superinterface methods (which were all abstract pre-default methods) 738 // need to be added to the vtable. 739 // With the addition of default methods, we have three new challenges: 740 // overpasses, static interface methods and private interface methods. 741 // Static and private interface methods do not get added to the vtable and 742 // are not seen by the method resolution process, so we skip those. 743 // Overpass methods are already in the vtable, so vtable lookup will 744 // find them and we don't need to add a miranda method to the end of 745 // the vtable. So we look for overpass methods and if they are found we 746 // return false. Note that we inherit our superclasses vtable, so 747 // the superclass' search also needs to use find_overpass so that if 748 // one is found we return false. 749 // False means - we don't need a miranda method added to the vtable. 750 // 751 // During the second run, default_methods is set up, so concrete methods from 752 // superinterfaces with matching names/signatures to default_methods are already 753 // in the default_methods list and do not need to be appended to the vtable 754 // as mirandas. Abstract methods may already have been handled via 755 // overpasses - either local or superclass overpasses, which may be 756 // in the vtable already. 757 // 758 // Pass 3: They are also checked by link resolution and selection, 759 // for invocation on a method (not interface method) reference that 760 // resolves to a method with an interface as its method_holder. 761 // Used as part of walking from the bottom of the vtable to find 762 // the vtable index for the miranda method. 763 // 764 // Part of the Miranda Rights in the US mean that if you do not have 765 // an attorney one will be appointed for you. 766 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 767 Array<Method*>* default_methods, const Klass* super) { 768 if (m->is_static() || m->is_private() || m->is_overpass()) { 769 return false; 770 } 771 Symbol* name = m->name(); 772 Symbol* signature = m->signature(); 773 774 // First look in local methods to see if already covered 775 if (InstanceKlass::find_local_method(class_methods, name, signature, 776 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) 777 { 778 return false; 779 } 780 781 // Check local default methods 782 if ((default_methods != NULL) && 783 (InstanceKlass::find_method(default_methods, name, signature) != NULL)) 784 { 785 return false; 786 } 787 788 // Iterate on all superclasses, which should be InstanceKlasses. 789 // Note that we explicitly look for overpasses at each level. 790 // Overpasses may or may not exist for supers for pass 1, 791 // they should have been created for pass 2 and later. 792 793 for (const Klass* cursuper = super; cursuper != NULL; cursuper = cursuper->super()) 794 { 795 if (InstanceKlass::cast(cursuper)->find_local_method(name, signature, 796 Klass::find_overpass, Klass::skip_static, Klass::skip_private) != NULL) { 797 return false; 798 } 799 } 800 801 return true; 802 } 803 804 // Scans current_interface_methods for miranda methods that do not 805 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 806 // in super (superclass). These mirandas are added to all_mirandas if it is 807 // not null; in addition, those that are not duplicates of miranda methods 808 // inherited by super from its interfaces are added to new_mirandas. 809 // Thus, new_mirandas will be the set of mirandas that this class introduces, 810 // all_mirandas will be the set of all mirandas applicable to this class 811 // including all defined in superclasses. 812 void klassVtable::add_new_mirandas_to_lists( 813 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 814 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 815 Array<Method*>* default_methods, const Klass* super) { 816 817 // iterate thru the current interface's method to see if it a miranda 818 int num_methods = current_interface_methods->length(); 819 for (int i = 0; i < num_methods; i++) { 820 Method* im = current_interface_methods->at(i); 821 bool is_duplicate = false; 822 int num_of_current_mirandas = new_mirandas->length(); 823 // check for duplicate mirandas in different interfaces we implement 824 for (int j = 0; j < num_of_current_mirandas; j++) { 825 Method* miranda = new_mirandas->at(j); 826 if ((im->name() == miranda->name()) && 827 (im->signature() == miranda->signature())) { 828 is_duplicate = true; 829 break; 830 } 831 } 832 833 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 834 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all? 835 const InstanceKlass *sk = InstanceKlass::cast(super); 836 // check if it is a duplicate of a super's miranda 837 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), Klass::find_defaults) == NULL) { 838 new_mirandas->append(im); 839 } 840 if (all_mirandas != NULL) { 841 all_mirandas->append(im); 842 } 843 } 844 } 845 } 846 } 847 848 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 849 GrowableArray<Method*>* all_mirandas, 850 const Klass* super, 851 Array<Method*>* class_methods, 852 Array<Method*>* default_methods, 853 Array<Klass*>* local_interfaces) { 854 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 855 856 // iterate thru the local interfaces looking for a miranda 857 int num_local_ifs = local_interfaces->length(); 858 for (int i = 0; i < num_local_ifs; i++) { 859 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 860 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 861 ik->methods(), class_methods, 862 default_methods, super); 863 // iterate thru each local's super interfaces 864 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 865 int num_super_ifs = super_ifs->length(); 866 for (int j = 0; j < num_super_ifs; j++) { 867 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 868 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 869 sik->methods(), class_methods, 870 default_methods, super); 871 } 872 } 873 } 874 875 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 876 // and append them into the vtable starting at index initialized, 877 // return the new value of initialized. 878 // Miranda methods use vtable entries, but do not get assigned a vtable_index 879 // The vtable_index is discovered by searching from the end of the vtable 880 int klassVtable::fill_in_mirandas(int initialized) { 881 GrowableArray<Method*> mirandas(20); 882 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 883 ik()->default_methods(), ik()->local_interfaces()); 884 for (int i = 0; i < mirandas.length(); i++) { 885 if (log_develop_is_enabled(Trace, vtables)) { 886 Method* meth = mirandas.at(i); 887 ResourceMark rm(Thread::current()); 888 outputStream* logst = Log(vtables)::trace_stream(); 889 if (meth != NULL) { 890 char* sig = meth->name_and_sig_as_C_string(); 891 logst->print("fill in mirandas with %s index %d, flags: ", 892 sig, initialized); 893 meth->print_linkage_flags(logst); 894 logst->cr(); 895 } 896 } 897 put_method_at(mirandas.at(i), initialized); 898 ++initialized; 899 } 900 return initialized; 901 } 902 903 // Copy this class's vtable to the vtable beginning at start. 904 // Used to copy superclass vtable to prefix of subclass's vtable. 905 void klassVtable::copy_vtable_to(vtableEntry* start) { 906 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 907 } 908 909 #if INCLUDE_JVMTI 910 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 911 // If old_method is default, find this vtable index in default_vtable_indices 912 // and replace that method in the _default_methods list 913 bool updated = false; 914 915 Array<Method*>* default_methods = ik()->default_methods(); 916 if (default_methods != NULL) { 917 int len = default_methods->length(); 918 for (int idx = 0; idx < len; idx++) { 919 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 920 if (default_methods->at(idx) == old_method) { 921 default_methods->at_put(idx, new_method); 922 updated = true; 923 } 924 break; 925 } 926 } 927 } 928 return updated; 929 } 930 931 // search the vtable for uses of either obsolete or EMCP methods 932 void klassVtable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 933 int prn_enabled = 0; 934 for (int index = 0; index < length(); index++) { 935 Method* old_method = unchecked_method_at(index); 936 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 937 continue; // skip uninteresting entries 938 } 939 assert(!old_method->is_deleted(), "vtable methods may not be deleted"); 940 941 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 942 943 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 944 assert(old_method != new_method, "sanity check"); 945 946 put_method_at(new_method, index); 947 // For default methods, need to update the _default_methods array 948 // which can only have one method entry for a given signature 949 bool updated_default = false; 950 if (old_method->is_default_method()) { 951 updated_default = adjust_default_method(index, old_method, new_method); 952 } 953 954 if (log_is_enabled(Info, redefine, class, update)) { 955 ResourceMark rm; 956 if (!(*trace_name_printed)) { 957 log_info(redefine, class, update) 958 ("adjust: klassname=%s for methods from name=%s", 959 _klass->external_name(), old_method->method_holder()->external_name()); 960 *trace_name_printed = true; 961 } 962 log_debug(redefine, class, update, vtables) 963 ("vtable method update: %s(%s), updated default = %s", 964 new_method->name()->as_C_string(), new_method->signature()->as_C_string(), updated_default ? "true" : "false"); 965 } 966 } 967 } 968 969 // a vtable should never contain old or obsolete methods 970 bool klassVtable::check_no_old_or_obsolete_entries() { 971 for (int i = 0; i < length(); i++) { 972 Method* m = unchecked_method_at(i); 973 if (m != NULL && 974 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 975 return false; 976 } 977 } 978 return true; 979 } 980 981 void klassVtable::dump_vtable() { 982 tty->print_cr("vtable dump --"); 983 for (int i = 0; i < length(); i++) { 984 Method* m = unchecked_method_at(i); 985 if (m != NULL) { 986 tty->print(" (%5d) ", i); 987 m->access_flags().print_on(tty); 988 if (m->is_default_method()) { 989 tty->print("default "); 990 } 991 if (m->is_overpass()) { 992 tty->print("overpass"); 993 } 994 tty->print(" -- "); 995 m->print_name(tty); 996 tty->cr(); 997 } 998 } 999 } 1000 #endif // INCLUDE_JVMTI 1001 1002 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 1003 void klassVtable::clear_vtable() { 1004 for (int i = 0; i < _length; i++) table()[i].clear(); 1005 } 1006 1007 bool klassVtable::is_initialized() { 1008 return _length == 0 || table()[0].method() != NULL; 1009 } 1010 1011 //----------------------------------------------------------------------------------------- 1012 // Itable code 1013 1014 // Initialize a itableMethodEntry 1015 void itableMethodEntry::initialize(Method* m) { 1016 if (m == NULL) return; 1017 1018 #ifdef ASSERT 1019 if (MetaspaceShared::is_in_shared_space((void*)&_method) && 1020 !MetaspaceShared::remapped_readwrite()) { 1021 // At runtime initialize_itable is rerun as part of link_class_impl() 1022 // for a shared class loaded by the non-boot loader. 1023 // The dumptime itable method entry should be the same as the runtime entry. 1024 assert(_method == m, "sanity"); 1025 } 1026 #endif 1027 _method = m; 1028 } 1029 1030 klassItable::klassItable(InstanceKlass* klass) { 1031 _klass = klass; 1032 1033 if (klass->itable_length() > 0) { 1034 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 1035 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 1036 // First offset entry points to the first method_entry 1037 intptr_t* method_entry = (intptr_t *)(((address)klass) + offset_entry->offset()); 1038 intptr_t* end = klass->end_of_itable(); 1039 1040 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass; 1041 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 1042 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 1043 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 1044 return; 1045 } 1046 } 1047 1048 // The length of the itable was either zero, or it has not yet been initialized. 1049 _table_offset = 0; 1050 _size_offset_table = 0; 1051 _size_method_table = 0; 1052 } 1053 1054 static int initialize_count = 0; 1055 1056 // Initialization 1057 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 1058 if (_klass->is_interface()) { 1059 // This needs to go after vtable indices are assigned but 1060 // before implementors need to know the number of itable indices. 1061 assign_itable_indices_for_interface(_klass); 1062 } 1063 1064 // Cannot be setup doing bootstrapping, interfaces don't have 1065 // itables, and klass with only ones entry have empty itables 1066 if (Universe::is_bootstrapping() || 1067 _klass->is_interface() || 1068 _klass->itable_length() == itableOffsetEntry::size()) return; 1069 1070 // There's alway an extra itable entry so we can null-terminate it. 1071 guarantee(size_offset_table() >= 1, "too small"); 1072 int num_interfaces = size_offset_table() - 1; 1073 if (num_interfaces > 0) { 1074 log_develop_debug(itables)("%3d: Initializing itables for %s", ++initialize_count, 1075 _klass->name()->as_C_string()); 1076 1077 1078 // Iterate through all interfaces 1079 int i; 1080 for(i = 0; i < num_interfaces; i++) { 1081 itableOffsetEntry* ioe = offset_entry(i); 1082 HandleMark hm(THREAD); 1083 Klass* interf = ioe->interface_klass(); 1084 assert(interf != NULL && ioe->offset() != 0, "bad offset entry in itable"); 1085 initialize_itable_for_interface(ioe->offset(), interf, checkconstraints, CHECK); 1086 } 1087 1088 } 1089 // Check that the last entry is empty 1090 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 1091 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 1092 } 1093 1094 1095 inline bool interface_method_needs_itable_index(Method* m) { 1096 if (m->is_static()) return false; // e.g., Stream.empty 1097 if (m->is_initializer()) return false; // <init> or <clinit> 1098 if (m->is_private()) return false; // requires invokeSpecial 1099 // If an interface redeclares a method from java.lang.Object, 1100 // it should already have a vtable index, don't touch it. 1101 // e.g., CharSequence.toString (from initialize_vtable) 1102 // if (m->has_vtable_index()) return false; // NO! 1103 return true; 1104 } 1105 1106 int klassItable::assign_itable_indices_for_interface(Klass* klass) { 1107 // an interface does not have an itable, but its methods need to be numbered 1108 log_develop_debug(itables)("%3d: Initializing itable indices for interface %s", 1109 ++initialize_count, klass->name()->as_C_string()); 1110 Array<Method*>* methods = InstanceKlass::cast(klass)->methods(); 1111 int nof_methods = methods->length(); 1112 int ime_num = 0; 1113 for (int i = 0; i < nof_methods; i++) { 1114 Method* m = methods->at(i); 1115 if (interface_method_needs_itable_index(m)) { 1116 assert(!m->is_final_method(), "no final interface methods"); 1117 // If m is already assigned a vtable index, do not disturb it. 1118 if (log_develop_is_enabled(Trace, itables)) { 1119 ResourceMark rm; 1120 outputStream* logst = Log(itables)::trace_stream(); 1121 assert(m != NULL, "methods can never be null"); 1122 const char* sig = m->name_and_sig_as_C_string(); 1123 if (m->has_vtable_index()) { 1124 logst->print("vtable index %d for method: %s, flags: ", m->vtable_index(), sig); 1125 } else { 1126 logst->print("itable index %d for method: %s, flags: ", ime_num, sig); 1127 } 1128 m->print_linkage_flags(logst); 1129 logst->cr(); 1130 } 1131 if (!m->has_vtable_index()) { 1132 // A shared method could have an initialized itable_index that 1133 // is < 0. 1134 assert(m->vtable_index() == Method::pending_itable_index || 1135 m->is_shared(), 1136 "set by initialize_vtable"); 1137 m->set_itable_index(ime_num); 1138 // Progress to next itable entry 1139 ime_num++; 1140 } 1141 } 1142 } 1143 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1144 return ime_num; 1145 } 1146 1147 int klassItable::method_count_for_interface(Klass* interf) { 1148 assert(interf->is_instance_klass(), "must be"); 1149 assert(interf->is_interface(), "must be"); 1150 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1151 int nof_methods = methods->length(); 1152 int length = 0; 1153 while (nof_methods > 0) { 1154 Method* m = methods->at(nof_methods-1); 1155 if (m->has_itable_index()) { 1156 length = m->itable_index() + 1; 1157 break; 1158 } 1159 nof_methods -= 1; 1160 } 1161 #ifdef ASSERT 1162 int nof_methods_copy = nof_methods; 1163 while (nof_methods_copy > 0) { 1164 Method* mm = methods->at(--nof_methods_copy); 1165 assert(!mm->has_itable_index() || mm->itable_index() < length, ""); 1166 } 1167 #endif //ASSERT 1168 // return the rightmost itable index, plus one; or 0 if no methods have 1169 // itable indices 1170 return length; 1171 } 1172 1173 1174 void klassItable::initialize_itable_for_interface(int method_table_offset, Klass* interf, bool checkconstraints, TRAPS) { 1175 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1176 int nof_methods = methods->length(); 1177 HandleMark hm; 1178 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable"); 1179 Handle interface_loader (THREAD, InstanceKlass::cast(interf)->class_loader()); 1180 1181 int ime_count = method_count_for_interface(interf); 1182 for (int i = 0; i < nof_methods; i++) { 1183 Method* m = methods->at(i); 1184 methodHandle target; 1185 if (m->has_itable_index()) { 1186 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1187 // to correctly enforce loader constraints for interface method inheritance 1188 target = LinkResolver::lookup_instance_method_in_klasses(_klass, m->name(), m->signature(), CHECK); 1189 } 1190 if (target == NULL || !target->is_public() || target->is_abstract()) { 1191 // Entry does not resolve. Leave it empty for AbstractMethodError. 1192 if (!(target == NULL) && !target->is_public()) { 1193 // Stuff an IllegalAccessError throwing method in there instead. 1194 itableOffsetEntry::method_entry(_klass, method_table_offset)[m->itable_index()]. 1195 initialize(Universe::throw_illegal_access_error()); 1196 } 1197 } else { 1198 // Entry did resolve, check loader constraints before initializing 1199 // if checkconstraints requested 1200 if (checkconstraints) { 1201 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1202 if (method_holder_loader() != interface_loader()) { 1203 ResourceMark rm(THREAD); 1204 Symbol* failed_type_symbol = 1205 SystemDictionary::check_signature_loaders(m->signature(), 1206 method_holder_loader, 1207 interface_loader, 1208 true, CHECK); 1209 if (failed_type_symbol != NULL) { 1210 const char* msg = "loader constraint violation in interface " 1211 "itable initialization: when resolving method \"%s\" the class" 1212 " loader (instance of %s) of the current class, %s, " 1213 "and the class loader (instance of %s) for interface " 1214 "%s have different Class objects for the type %s " 1215 "used in the signature"; 1216 char* sig = target()->name_and_sig_as_C_string(); 1217 const char* loader1 = SystemDictionary::loader_name(method_holder_loader()); 1218 char* current = _klass->name()->as_C_string(); 1219 const char* loader2 = SystemDictionary::loader_name(interface_loader()); 1220 char* iface = InstanceKlass::cast(interf)->name()->as_C_string(); 1221 char* failed_type_name = failed_type_symbol->as_C_string(); 1222 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 1223 strlen(current) + strlen(loader2) + strlen(iface) + 1224 strlen(failed_type_name); 1225 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1226 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 1227 iface, failed_type_name); 1228 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1229 } 1230 } 1231 } 1232 1233 // ime may have moved during GC so recalculate address 1234 int ime_num = m->itable_index(); 1235 assert(ime_num < ime_count, "oob"); 1236 itableOffsetEntry::method_entry(_klass, method_table_offset)[ime_num].initialize(target()); 1237 if (log_develop_is_enabled(Trace, itables)) { 1238 ResourceMark rm(THREAD); 1239 if (target() != NULL) { 1240 outputStream* logst = Log(itables)::trace_stream(); 1241 char* sig = target()->name_and_sig_as_C_string(); 1242 logst->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1243 interf->internal_name(), ime_num, sig, 1244 target()->method_holder()->internal_name()); 1245 logst->print("target_method flags: "); 1246 target()->print_linkage_flags(logst); 1247 logst->cr(); 1248 } 1249 } 1250 } 1251 } 1252 } 1253 1254 #if INCLUDE_JVMTI 1255 // search the itable for uses of either obsolete or EMCP methods 1256 void klassItable::adjust_method_entries(InstanceKlass* holder, bool * trace_name_printed) { 1257 1258 itableMethodEntry* ime = method_entry(0); 1259 for (int i = 0; i < _size_method_table; i++, ime++) { 1260 Method* old_method = ime->method(); 1261 if (old_method == NULL || old_method->method_holder() != holder || !old_method->is_old()) { 1262 continue; // skip uninteresting entries 1263 } 1264 assert(!old_method->is_deleted(), "itable methods may not be deleted"); 1265 1266 Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum()); 1267 1268 assert(new_method != NULL, "method_with_idnum() should not be NULL"); 1269 assert(old_method != new_method, "sanity check"); 1270 1271 ime->initialize(new_method); 1272 1273 if (log_is_enabled(Info, redefine, class, update)) { 1274 ResourceMark rm; 1275 if (!(*trace_name_printed)) { 1276 log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name()); 1277 *trace_name_printed = true; 1278 } 1279 log_trace(redefine, class, update, itables) 1280 ("itable method update: %s(%s)", new_method->name()->as_C_string(), new_method->signature()->as_C_string()); 1281 } 1282 } 1283 } 1284 1285 // an itable should never contain old or obsolete methods 1286 bool klassItable::check_no_old_or_obsolete_entries() { 1287 itableMethodEntry* ime = method_entry(0); 1288 for (int i = 0; i < _size_method_table; i++) { 1289 Method* m = ime->method(); 1290 if (m != NULL && 1291 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1292 return false; 1293 } 1294 ime++; 1295 } 1296 return true; 1297 } 1298 1299 void klassItable::dump_itable() { 1300 itableMethodEntry* ime = method_entry(0); 1301 tty->print_cr("itable dump --"); 1302 for (int i = 0; i < _size_method_table; i++) { 1303 Method* m = ime->method(); 1304 if (m != NULL) { 1305 tty->print(" (%5d) ", i); 1306 m->access_flags().print_on(tty); 1307 if (m->is_default_method()) { 1308 tty->print("default "); 1309 } 1310 tty->print(" -- "); 1311 m->print_name(tty); 1312 tty->cr(); 1313 } 1314 ime++; 1315 } 1316 } 1317 #endif // INCLUDE_JVMTI 1318 1319 // Setup 1320 class InterfaceVisiterClosure : public StackObj { 1321 public: 1322 virtual void doit(Klass* intf, int method_count) = 0; 1323 }; 1324 1325 // Visit all interfaces with at least one itable method 1326 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1327 // Handle array argument 1328 for(int i = 0; i < transitive_intf->length(); i++) { 1329 Klass* intf = transitive_intf->at(i); 1330 assert(intf->is_interface(), "sanity check"); 1331 1332 // Find no. of itable methods 1333 int method_count = 0; 1334 // method_count = klassItable::method_count_for_interface(intf); 1335 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1336 if (methods->length() > 0) { 1337 for (int i = methods->length(); --i >= 0; ) { 1338 if (interface_method_needs_itable_index(methods->at(i))) { 1339 method_count++; 1340 } 1341 } 1342 } 1343 1344 // Only count interfaces with at least one method 1345 if (method_count > 0) { 1346 blk->doit(intf, method_count); 1347 } 1348 } 1349 } 1350 1351 class CountInterfacesClosure : public InterfaceVisiterClosure { 1352 private: 1353 int _nof_methods; 1354 int _nof_interfaces; 1355 public: 1356 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1357 1358 int nof_methods() const { return _nof_methods; } 1359 int nof_interfaces() const { return _nof_interfaces; } 1360 1361 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1362 }; 1363 1364 class SetupItableClosure : public InterfaceVisiterClosure { 1365 private: 1366 itableOffsetEntry* _offset_entry; 1367 itableMethodEntry* _method_entry; 1368 address _klass_begin; 1369 public: 1370 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1371 _klass_begin = klass_begin; 1372 _offset_entry = offset_entry; 1373 _method_entry = method_entry; 1374 } 1375 1376 itableMethodEntry* method_entry() const { return _method_entry; } 1377 1378 void doit(Klass* intf, int method_count) { 1379 int offset = ((address)_method_entry) - _klass_begin; 1380 _offset_entry->initialize(intf, offset); 1381 _offset_entry++; 1382 _method_entry += method_count; 1383 } 1384 }; 1385 1386 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 1387 // Count no of interfaces and total number of interface methods 1388 CountInterfacesClosure cic; 1389 visit_all_interfaces(transitive_interfaces, &cic); 1390 1391 // There's alway an extra itable entry so we can null-terminate it. 1392 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1393 1394 // Statistics 1395 update_stats(itable_size * wordSize); 1396 1397 return itable_size; 1398 } 1399 1400 1401 // Fill out offset table and interface klasses into the itable space 1402 void klassItable::setup_itable_offset_table(InstanceKlass* klass) { 1403 if (klass->itable_length() == 0) return; 1404 assert(!klass->is_interface(), "Should have zero length itable"); 1405 1406 // Count no of interfaces and total number of interface methods 1407 CountInterfacesClosure cic; 1408 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1409 int nof_methods = cic.nof_methods(); 1410 int nof_interfaces = cic.nof_interfaces(); 1411 1412 // Add one extra entry so we can null-terminate the table 1413 nof_interfaces++; 1414 1415 assert(compute_itable_size(klass->transitive_interfaces()) == 1416 calc_itable_size(nof_interfaces, nof_methods), 1417 "mismatch calculation of itable size"); 1418 1419 // Fill-out offset table 1420 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1421 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1422 intptr_t* end = klass->end_of_itable(); 1423 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1424 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1425 1426 // Visit all interfaces and initialize itable offset table 1427 SetupItableClosure sic((address)klass, ioe, ime); 1428 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1429 1430 #ifdef ASSERT 1431 ime = sic.method_entry(); 1432 oop* v = (oop*) klass->end_of_itable(); 1433 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1434 #endif 1435 } 1436 1437 1438 // inverse to itable_index 1439 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1440 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1441 assert(intf->verify_itable_index(itable_index), ""); 1442 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1443 1444 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1445 return NULL; // help caller defend against bad indices 1446 1447 int index = itable_index; 1448 Method* m = methods->at(index); 1449 int index2 = -1; 1450 while (!m->has_itable_index() || 1451 (index2 = m->itable_index()) != itable_index) { 1452 assert(index2 < itable_index, "monotonic"); 1453 if (++index == methods->length()) 1454 return NULL; 1455 m = methods->at(index); 1456 } 1457 assert(m->itable_index() == itable_index, "correct inverse"); 1458 1459 return m; 1460 } 1461 1462 void klassVtable::verify(outputStream* st, bool forced) { 1463 // make sure table is initialized 1464 if (!Universe::is_fully_initialized()) return; 1465 #ifndef PRODUCT 1466 // avoid redundant verifies 1467 if (!forced && _verify_count == Universe::verify_count()) return; 1468 _verify_count = Universe::verify_count(); 1469 #endif 1470 oop* end_of_obj = (oop*)_klass + _klass->size(); 1471 oop* end_of_vtable = (oop *)&table()[_length]; 1472 if (end_of_vtable > end_of_obj) { 1473 fatal("klass %s: klass object too short (vtable extends beyond end)", 1474 _klass->internal_name()); 1475 } 1476 1477 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1478 // verify consistency with superKlass vtable 1479 Klass* super = _klass->super(); 1480 if (super != NULL) { 1481 InstanceKlass* sk = InstanceKlass::cast(super); 1482 klassVtable vt = sk->vtable(); 1483 for (int i = 0; i < vt.length(); i++) { 1484 verify_against(st, &vt, i); 1485 } 1486 } 1487 } 1488 1489 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1490 vtableEntry* vte = &vt->table()[index]; 1491 if (vte->method()->name() != table()[index].method()->name() || 1492 vte->method()->signature() != table()[index].method()->signature()) { 1493 fatal("mismatched name/signature of vtable entries"); 1494 } 1495 } 1496 1497 #ifndef PRODUCT 1498 void klassVtable::print() { 1499 ResourceMark rm; 1500 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1501 for (int i = 0; i < length(); i++) { 1502 table()[i].print(); 1503 tty->cr(); 1504 } 1505 } 1506 #endif 1507 1508 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1509 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1510 Klass* vtklass = vt->klass(); 1511 if (vtklass->is_instance_klass() && 1512 (InstanceKlass::cast(vtklass)->major_version() >= klassVtable::VTABLE_TRANSITIVE_OVERRIDE_VERSION)) { 1513 assert(method() != NULL, "must have set method"); 1514 } 1515 if (method() != NULL) { 1516 method()->verify(); 1517 // we sub_type, because it could be a miranda method 1518 if (!vtklass->is_subtype_of(method()->method_holder())) { 1519 #ifndef PRODUCT 1520 print(); 1521 #endif 1522 fatal("vtableEntry " PTR_FORMAT ": method is from subclass", p2i(this)); 1523 } 1524 } 1525 } 1526 1527 #ifndef PRODUCT 1528 1529 void vtableEntry::print() { 1530 ResourceMark rm; 1531 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1532 if (Verbose) { 1533 tty->print("m " PTR_FORMAT " ", p2i(method())); 1534 } 1535 } 1536 1537 class VtableStats : AllStatic { 1538 public: 1539 static int no_klasses; // # classes with vtables 1540 static int no_array_klasses; // # array classes 1541 static int no_instance_klasses; // # instanceKlasses 1542 static int sum_of_vtable_len; // total # of vtable entries 1543 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1544 static int fixed; // total fixed overhead in bytes 1545 static int filler; // overhead caused by filler bytes 1546 static int entries; // total bytes consumed by vtable entries 1547 static int array_entries; // total bytes consumed by array vtable entries 1548 1549 static void do_class(Klass* k) { 1550 Klass* kl = k; 1551 klassVtable vt = kl->vtable(); 1552 no_klasses++; 1553 if (kl->is_instance_klass()) { 1554 no_instance_klasses++; 1555 kl->array_klasses_do(do_class); 1556 } 1557 if (kl->is_array_klass()) { 1558 no_array_klasses++; 1559 sum_of_array_vtable_len += vt.length(); 1560 } 1561 sum_of_vtable_len += vt.length(); 1562 } 1563 1564 static void compute() { 1565 ClassLoaderDataGraph::classes_do(do_class); 1566 fixed = no_klasses * oopSize; // vtable length 1567 // filler size is a conservative approximation 1568 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1569 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1570 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1571 } 1572 }; 1573 1574 int VtableStats::no_klasses = 0; 1575 int VtableStats::no_array_klasses = 0; 1576 int VtableStats::no_instance_klasses = 0; 1577 int VtableStats::sum_of_vtable_len = 0; 1578 int VtableStats::sum_of_array_vtable_len = 0; 1579 int VtableStats::fixed = 0; 1580 int VtableStats::filler = 0; 1581 int VtableStats::entries = 0; 1582 int VtableStats::array_entries = 0; 1583 1584 void klassVtable::print_statistics() { 1585 ResourceMark rm; 1586 HandleMark hm; 1587 VtableStats::compute(); 1588 tty->print_cr("vtable statistics:"); 1589 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1590 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1591 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1592 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1593 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1594 tty->print_cr("%6d bytes total", total); 1595 } 1596 1597 int klassItable::_total_classes; // Total no. of classes with itables 1598 long klassItable::_total_size; // Total no. of bytes used for itables 1599 1600 void klassItable::print_statistics() { 1601 tty->print_cr("itable statistics:"); 1602 tty->print_cr("%6d classes with itables", _total_classes); 1603 tty->print_cr("%6lu K uses for itables (average by class: %ld bytes)", _total_size / K, _total_size / _total_classes); 1604 } 1605 1606 #endif // PRODUCT