1 /* 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "classfile/vmSymbols.hpp" 28 #include "gc_implementation/shared/markSweep.inline.hpp" 29 #include "memory/gcLocker.hpp" 30 #include "memory/resourceArea.hpp" 31 #include "memory/universe.inline.hpp" 32 #include "oops/instanceKlass.hpp" 33 #include "oops/klassVtable.hpp" 34 #include "oops/method.hpp" 35 #include "oops/objArrayOop.hpp" 36 #include "oops/oop.inline.hpp" 37 #include "prims/jvmtiRedefineClassesTrace.hpp" 38 #include "runtime/arguments.hpp" 39 #include "runtime/handles.inline.hpp" 40 #include "utilities/copy.hpp" 41 42 inline InstanceKlass* klassVtable::ik() const { 43 Klass* k = _klass(); 44 assert(k->oop_is_instance(), "not an InstanceKlass"); 45 return (InstanceKlass*)k; 46 } 47 48 49 // this function computes the vtable size (including the size needed for miranda 50 // methods) and the number of miranda methods in this class 51 // Note on Miranda methods: Let's say there is a class C that implements 52 // interface I. Let's say there is a method m in I that neither C nor any 53 // of its super classes implement (i.e there is no method of any access, with 54 // the same name and signature as m), then m is a Miranda method which is 55 // entered as a public abstract method in C's vtable. From then on it should 56 // treated as any other public method in C for method over-ride purposes. 57 void klassVtable::compute_vtable_size_and_num_mirandas( 58 int* vtable_length_ret, int* num_new_mirandas, 59 GrowableArray<Method*>* all_mirandas, Klass* super, 60 Array<Method*>* methods, AccessFlags class_flags, 61 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces, 62 TRAPS) { 63 No_Safepoint_Verifier nsv; 64 65 // set up default result values 66 int vtable_length = 0; 67 68 // start off with super's vtable length 69 InstanceKlass* sk = (InstanceKlass*)super; 70 vtable_length = super == NULL ? 0 : sk->vtable_length(); 71 72 // go thru each method in the methods table to see if it needs a new entry 73 int len = methods->length(); 74 for (int i = 0; i < len; i++) { 75 assert(methods->at(i)->is_method(), "must be a Method*"); 76 methodHandle mh(THREAD, methods->at(i)); 77 78 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) { 79 vtable_length += vtableEntry::size(); // we need a new entry 80 } 81 } 82 83 GrowableArray<Method*> new_mirandas(20); 84 // compute the number of mirandas methods that must be added to the end 85 get_mirandas(&new_mirandas, all_mirandas, super, methods, local_interfaces); 86 *num_new_mirandas = new_mirandas.length(); 87 88 vtable_length += *num_new_mirandas * vtableEntry::size(); 89 90 if (Universe::is_bootstrapping() && vtable_length == 0) { 91 // array classes don't have their superclass set correctly during 92 // bootstrapping 93 vtable_length = Universe::base_vtable_size(); 94 } 95 96 if (super == NULL && !Universe::is_bootstrapping() && 97 vtable_length != Universe::base_vtable_size()) { 98 // Someone is attempting to redefine java.lang.Object incorrectly. The 99 // only way this should happen is from 100 // SystemDictionary::resolve_from_stream(), which will detect this later 101 // and throw a security exception. So don't assert here to let 102 // the exception occur. 103 vtable_length = Universe::base_vtable_size(); 104 } 105 assert(super != NULL || vtable_length == Universe::base_vtable_size(), 106 "bad vtable size for class Object"); 107 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 108 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 109 110 *vtable_length_ret = vtable_length; 111 } 112 113 int klassVtable::index_of(Method* m, int len) const { 114 assert(m->vtable_index() >= 0, "do not ask this of non-vtable methods"); 115 return m->vtable_index(); 116 } 117 118 int klassVtable::initialize_from_super(KlassHandle super) { 119 if (super.is_null()) { 120 return 0; 121 } else { 122 // copy methods from superKlass 123 // can't inherit from array class, so must be InstanceKlass 124 assert(super->oop_is_instance(), "must be instance klass"); 125 InstanceKlass* sk = (InstanceKlass*)super(); 126 klassVtable* superVtable = sk->vtable(); 127 assert(superVtable->length() <= _length, "vtable too short"); 128 #ifdef ASSERT 129 superVtable->verify(tty, true); 130 #endif 131 superVtable->copy_vtable_to(table()); 132 #ifndef PRODUCT 133 if (PrintVtables && Verbose) { 134 ResourceMark rm; 135 tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length); 136 } 137 #endif 138 return superVtable->length(); 139 } 140 } 141 142 // Revised lookup semantics introduced 1.3 (Kestral beta) 143 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { 144 145 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 146 KlassHandle super (THREAD, klass()->java_super()); 147 int nofNewEntries = 0; 148 149 150 if (PrintVtables && !klass()->oop_is_array()) { 151 ResourceMark rm(THREAD); 152 tty->print_cr("Initializing: %s", _klass->name()->as_C_string()); 153 } 154 155 #ifdef ASSERT 156 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 157 oop* end_of_vtable = (oop*)&table()[_length]; 158 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 159 #endif 160 161 if (Universe::is_bootstrapping()) { 162 // just clear everything 163 for (int i = 0; i < _length; i++) table()[i].clear(); 164 return; 165 } 166 167 int super_vtable_len = initialize_from_super(super); 168 if (klass()->oop_is_array()) { 169 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 170 } else { 171 assert(_klass->oop_is_instance(), "must be InstanceKlass"); 172 173 Array<Method*>* methods = ik()->methods(); 174 int len = methods->length(); 175 int initialized = super_vtable_len; 176 177 // update_inherited_vtable can stop for gc - ensure using handles 178 for (int i = 0; i < len; i++) { 179 HandleMark hm(THREAD); 180 assert(methods->at(i)->is_method(), "must be a Method*"); 181 methodHandle mh(THREAD, methods->at(i)); 182 183 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, checkconstraints, CHECK); 184 185 if (needs_new_entry) { 186 put_method_at(mh(), initialized); 187 mh()->set_vtable_index(initialized); // set primary vtable index 188 initialized++; 189 } 190 } 191 192 // add miranda methods; it will also update the value of initialized 193 fill_in_mirandas(&initialized); 194 195 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 196 // package_private -> publicprotected), the vtable might actually be smaller than our initial 197 // calculation. 198 assert(initialized <= _length, "vtable initialization failed"); 199 for(;initialized < _length; initialized++) { 200 put_method_at(NULL, initialized); 201 } 202 NOT_PRODUCT(verify(tty, true)); 203 } 204 } 205 206 // Called for cases where a method does not override its superclass' vtable entry 207 // For bytecodes not produced by javac together it is possible that a method does not override 208 // the superclass's method, but might indirectly override a super-super class's vtable entry 209 // If none found, return a null superk, else return the superk of the method this does override 210 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, 211 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 212 InstanceKlass* superk = initialsuper; 213 while (superk != NULL && superk->super() != NULL) { 214 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 215 klassVtable* ssVtable = supersuperklass->vtable(); 216 if (vtable_index < ssVtable->length()) { 217 Method* super_method = ssVtable->method_at(vtable_index); 218 #ifndef PRODUCT 219 Symbol* name= target_method()->name(); 220 Symbol* signature = target_method()->signature(); 221 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 222 #endif 223 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 224 #ifndef PRODUCT 225 if (PrintVtables && Verbose) { 226 ResourceMark rm(THREAD); 227 tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ", 228 supersuperklass->internal_name(), 229 _klass->internal_name(), (target_method() != NULL) ? 230 target_method()->name()->as_C_string() : "<NULL>", vtable_index); 231 super_method->access_flags().print_on(tty); 232 tty->print("overriders flags: "); 233 target_method->access_flags().print_on(tty); 234 tty->cr(); 235 } 236 #endif /*PRODUCT*/ 237 break; // return found superk 238 } 239 } else { 240 // super class has no vtable entry here, stop transitive search 241 superk = (InstanceKlass*)NULL; 242 break; 243 } 244 // if no override found yet, continue to search up 245 superk = InstanceKlass::cast(superk->super()); 246 } 247 248 return superk; 249 } 250 251 // Methods that are "effectively" final don't need vtable entries. 252 bool method_is_effectively_final( 253 AccessFlags klass_flags, methodHandle target) { 254 return target->is_final() || klass_flags.is_final() && !target->is_overpass(); 255 } 256 257 // Update child's copy of super vtable for overrides 258 // OR return true if a new vtable entry is required 259 // Only called for InstanceKlass's, i.e. not for arrays 260 // If that changed, could not use _klass as handle for klass 261 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, int super_vtable_len, 262 bool checkconstraints, TRAPS) { 263 ResourceMark rm; 264 bool allocate_new = true; 265 assert(klass->oop_is_instance(), "must be InstanceKlass"); 266 267 // Initialize the method's vtable index to "nonvirtual". 268 // If we allocate a vtable entry, we will update it to a non-negative number. 269 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 270 271 // Static and <init> methods are never in 272 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { 273 return false; 274 } 275 276 if (method_is_effectively_final(klass->access_flags(), target_method)) { 277 // a final method never needs a new entry; final methods can be statically 278 // resolved and they have to be present in the vtable only if they override 279 // a super's method, in which case they re-use its entry 280 allocate_new = false; 281 } 282 283 // we need a new entry if there is no superclass 284 if (klass->super() == NULL) { 285 return allocate_new; 286 } 287 288 // private methods always have a new entry in the vtable 289 // specification interpretation since classic has 290 // private methods not overriding 291 if (target_method()->is_private()) { 292 return allocate_new; 293 } 294 295 // search through the vtable and update overridden entries 296 // Since check_signature_loaders acquires SystemDictionary_lock 297 // which can block for gc, once we are in this loop, use handles 298 // For classfiles built with >= jdk7, we now look for transitive overrides 299 300 Symbol* name = target_method()->name(); 301 Symbol* signature = target_method()->signature(); 302 Handle target_loader(THREAD, _klass()->class_loader()); 303 Symbol* target_classname = _klass->name(); 304 for(int i = 0; i < super_vtable_len; i++) { 305 Method* super_method = method_at(i); 306 // Check if method name matches 307 if (super_method->name() == name && super_method->signature() == signature) { 308 309 // get super_klass for method_holder for the found method 310 InstanceKlass* super_klass = super_method->method_holder(); 311 312 if ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) || 313 ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 314 && ((super_klass = find_transitive_override(super_klass, target_method, i, target_loader, 315 target_classname, THREAD)) != (InstanceKlass*)NULL))) { 316 // overriding, so no new entry 317 allocate_new = false; 318 319 if (checkconstraints) { 320 // Override vtable entry if passes loader constraint check 321 // if loader constraint checking requested 322 // No need to visit his super, since he and his super 323 // have already made any needed loader constraints. 324 // Since loader constraints are transitive, it is enough 325 // to link to the first super, and we get all the others. 326 Handle super_loader(THREAD, super_klass->class_loader()); 327 328 if (target_loader() != super_loader()) { 329 ResourceMark rm(THREAD); 330 char* failed_type_name = 331 SystemDictionary::check_signature_loaders(signature, target_loader, 332 super_loader, true, 333 CHECK_(false)); 334 if (failed_type_name != NULL) { 335 const char* msg = "loader constraint violation: when resolving " 336 "overridden method \"%s\" the class loader (instance" 337 " of %s) of the current class, %s, and its superclass loader " 338 "(instance of %s), have different Class objects for the type " 339 "%s used in the signature"; 340 char* sig = target_method()->name_and_sig_as_C_string(); 341 const char* loader1 = SystemDictionary::loader_name(target_loader()); 342 char* current = _klass->name()->as_C_string(); 343 const char* loader2 = SystemDictionary::loader_name(super_loader()); 344 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 345 strlen(current) + strlen(loader2) + strlen(failed_type_name); 346 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 347 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 348 failed_type_name); 349 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); 350 } 351 } 352 } 353 354 put_method_at(target_method(), i); 355 target_method()->set_vtable_index(i); 356 #ifndef PRODUCT 357 if (PrintVtables && Verbose) { 358 tty->print("overriding with %s::%s index %d, original flags: ", 359 _klass->internal_name(), (target_method() != NULL) ? 360 target_method()->name()->as_C_string() : "<NULL>", i); 361 super_method->access_flags().print_on(tty); 362 tty->print("overriders flags: "); 363 target_method->access_flags().print_on(tty); 364 tty->cr(); 365 } 366 #endif /*PRODUCT*/ 367 } else { 368 // allocate_new = true; default. We might override one entry, 369 // but not override another. Once we override one, not need new 370 #ifndef PRODUCT 371 if (PrintVtables && Verbose) { 372 tty->print("NOT overriding with %s::%s index %d, original flags: ", 373 _klass->internal_name(), (target_method() != NULL) ? 374 target_method()->name()->as_C_string() : "<NULL>", i); 375 super_method->access_flags().print_on(tty); 376 tty->print("overriders flags: "); 377 target_method->access_flags().print_on(tty); 378 tty->cr(); 379 } 380 #endif /*PRODUCT*/ 381 } 382 } 383 } 384 return allocate_new; 385 } 386 387 void klassVtable::put_method_at(Method* m, int index) { 388 #ifndef PRODUCT 389 if (PrintVtables && Verbose) { 390 ResourceMark rm; 391 tty->print_cr("adding %s::%s at index %d", _klass->internal_name(), 392 (m != NULL) ? m->name()->as_C_string() : "<NULL>", index); 393 } 394 #endif 395 table()[index].set(m); 396 } 397 398 // Find out if a method "m" with superclass "super", loader "classloader" and 399 // name "classname" needs a new vtable entry. Let P be a class package defined 400 // by "classloader" and "classname". 401 // NOTE: The logic used here is very similar to the one used for computing 402 // the vtables indices for a method. We cannot directly use that function because, 403 // we allocate the InstanceKlass at load time, and that requires that the 404 // superclass has been loaded. 405 // However, the vtable entries are filled in at link time, and therefore 406 // the superclass' vtable may not yet have been filled in. 407 bool klassVtable::needs_new_vtable_entry(methodHandle target_method, 408 Klass* super, 409 Handle classloader, 410 Symbol* classname, 411 AccessFlags class_flags, 412 TRAPS) { 413 414 if (method_is_effectively_final(class_flags, target_method) || 415 // a final method never needs a new entry; final methods can be statically 416 // resolved and they have to be present in the vtable only if they override 417 // a super's method, in which case they re-use its entry 418 (target_method()->is_static()) || 419 // static methods don't need to be in vtable 420 (target_method()->name() == vmSymbols::object_initializer_name()) 421 // <init> is never called dynamically-bound 422 ) { 423 return false; 424 } 425 426 // we need a new entry if there is no superclass 427 if (super == NULL) { 428 return true; 429 } 430 431 // private methods always have a new entry in the vtable 432 // specification interpretation since classic has 433 // private methods not overriding 434 if (target_method()->is_private()) { 435 return true; 436 } 437 438 // search through the super class hierarchy to see if we need 439 // a new entry 440 ResourceMark rm; 441 Symbol* name = target_method()->name(); 442 Symbol* signature = target_method()->signature(); 443 Klass* k = super; 444 Method* super_method = NULL; 445 InstanceKlass *holder = NULL; 446 Method* recheck_method = NULL; 447 while (k != NULL) { 448 // lookup through the hierarchy for a method with matching name and sign. 449 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 450 if (super_method == NULL) { 451 break; // we still have to search for a matching miranda method 452 } 453 // get the class holding the matching method 454 // make sure you use that class for is_override 455 InstanceKlass* superk = super_method->method_holder(); 456 // we want only instance method matches 457 // pretend private methods are not in the super vtable 458 // since we do override around them: e.g. a.m pub/b.m private/c.m pub, 459 // ignore private, c.m pub does override a.m pub 460 // For classes that were not javac'd together, we also do transitive overriding around 461 // methods that have less accessibility 462 if ((!super_method->is_static()) && 463 (!super_method->is_private())) { 464 if (superk->is_override(super_method, classloader, classname, THREAD)) { 465 return false; 466 // else keep looking for transitive overrides 467 } 468 } 469 470 // Start with lookup result and continue to search up 471 k = superk->super(); // haven't found an override match yet; continue to look 472 } 473 474 // if the target method is public or protected it may have a matching 475 // miranda method in the super, whose entry it should re-use. 476 // Actually, to handle cases that javac would not generate, we need 477 // this check for all access permissions. 478 InstanceKlass *sk = InstanceKlass::cast(super); 479 if (sk->has_miranda_methods()) { 480 if (sk->lookup_method_in_all_interfaces(name, signature) != NULL) { 481 return false; // found a matching miranda; we do not need a new entry 482 } 483 } 484 return true; // found no match; we need a new entry 485 } 486 487 // Support for miranda methods 488 489 // get the vtable index of a miranda method with matching "name" and "signature" 490 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 491 // search from the bottom, might be faster 492 for (int i = (length() - 1); i >= 0; i--) { 493 Method* m = table()[i].method(); 494 if (is_miranda_entry_at(i) && 495 m->name() == name && m->signature() == signature) { 496 return i; 497 } 498 } 499 return Method::invalid_vtable_index; 500 } 501 502 // check if an entry is miranda 503 bool klassVtable::is_miranda_entry_at(int i) { 504 Method* m = method_at(i); 505 Klass* method_holder = m->method_holder(); 506 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 507 508 // miranda methods are interface methods in a class's vtable 509 if (mhk->is_interface()) { 510 assert(m->is_public(), "should be public"); 511 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 512 assert(is_miranda(m, ik()->methods(), ik()->super()), "should be a miranda_method"); 513 return true; 514 } 515 return false; 516 } 517 518 // check if a method is a miranda method, given a class's methods table and it's super 519 // the caller must make sure that the method belongs to an interface implemented by the class 520 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, Klass* super) { 521 Symbol* name = m->name(); 522 Symbol* signature = m->signature(); 523 if (InstanceKlass::find_method(class_methods, name, signature) == NULL) { 524 // did not find it in the method table of the current class 525 if (super == NULL) { 526 // super doesn't exist 527 return true; 528 } 529 530 Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature); 531 if (mo == NULL || mo->access_flags().is_private() ) { 532 // super class hierarchy does not implement it or protection is different 533 return true; 534 } 535 } 536 537 return false; 538 } 539 540 void klassVtable::add_new_mirandas_to_lists( 541 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 542 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 543 Klass* super) { 544 // iterate thru the current interface's method to see if it a miranda 545 int num_methods = current_interface_methods->length(); 546 for (int i = 0; i < num_methods; i++) { 547 Method* im = current_interface_methods->at(i); 548 bool is_duplicate = false; 549 int num_of_current_mirandas = new_mirandas->length(); 550 // check for duplicate mirandas in different interfaces we implement 551 for (int j = 0; j < num_of_current_mirandas; j++) { 552 Method* miranda = new_mirandas->at(j); 553 if ((im->name() == miranda->name()) && 554 (im->signature() == miranda->signature())) { 555 is_duplicate = true; 556 break; 557 } 558 } 559 560 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 561 if (is_miranda(im, class_methods, super)) { // is it a miranda at all? 562 InstanceKlass *sk = InstanceKlass::cast(super); 563 // check if it is a duplicate of a super's miranda 564 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature()) == NULL) { 565 new_mirandas->append(im); 566 } 567 if (all_mirandas != NULL) { 568 all_mirandas->append(im); 569 } 570 } 571 } 572 } 573 } 574 575 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 576 GrowableArray<Method*>* all_mirandas, 577 Klass* super, Array<Method*>* class_methods, 578 Array<Klass*>* local_interfaces) { 579 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 580 581 // iterate thru the local interfaces looking for a miranda 582 int num_local_ifs = local_interfaces->length(); 583 for (int i = 0; i < num_local_ifs; i++) { 584 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 585 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 586 ik->methods(), class_methods, super); 587 // iterate thru each local's super interfaces 588 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 589 int num_super_ifs = super_ifs->length(); 590 for (int j = 0; j < num_super_ifs; j++) { 591 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 592 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 593 sik->methods(), class_methods, super); 594 } 595 } 596 } 597 598 // fill in mirandas 599 void klassVtable::fill_in_mirandas(int* initialized) { 600 GrowableArray<Method*> mirandas(20); 601 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 602 ik()->local_interfaces()); 603 for (int i = 0; i < mirandas.length(); i++) { 604 put_method_at(mirandas.at(i), *initialized); 605 ++(*initialized); 606 } 607 } 608 609 void klassVtable::copy_vtable_to(vtableEntry* start) { 610 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 611 } 612 613 void klassVtable::adjust_method_entries(Method** old_methods, Method** new_methods, 614 int methods_length, bool * trace_name_printed) { 615 // search the vtable for uses of either obsolete or EMCP methods 616 for (int j = 0; j < methods_length; j++) { 617 Method* old_method = old_methods[j]; 618 Method* new_method = new_methods[j]; 619 620 // In the vast majority of cases we could get the vtable index 621 // by using: old_method->vtable_index() 622 // However, there are rare cases, eg. sun.awt.X11.XDecoratedPeer.getX() 623 // in sun.awt.X11.XFramePeer where methods occur more than once in the 624 // vtable, so, alas, we must do an exhaustive search. 625 for (int index = 0; index < length(); index++) { 626 if (unchecked_method_at(index) == old_method) { 627 put_method_at(new_method, index); 628 629 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 630 if (!(*trace_name_printed)) { 631 // RC_TRACE_MESG macro has an embedded ResourceMark 632 RC_TRACE_MESG(("adjust: name=%s", 633 old_method->method_holder()->external_name())); 634 *trace_name_printed = true; 635 } 636 // RC_TRACE macro has an embedded ResourceMark 637 RC_TRACE(0x00100000, ("vtable method update: %s(%s)", 638 new_method->name()->as_C_string(), 639 new_method->signature()->as_C_string())); 640 } 641 // cannot 'break' here; see for-loop comment above. 642 } 643 } 644 } 645 } 646 647 // a vtable should never contain old or obsolete methods 648 bool klassVtable::check_no_old_or_obsolete_entries() { 649 for (int i = 0; i < length(); i++) { 650 Method* m = unchecked_method_at(i); 651 if (m != NULL && 652 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 653 return false; 654 } 655 } 656 return true; 657 } 658 659 void klassVtable::dump_vtable() { 660 tty->print_cr("vtable dump --"); 661 for (int i = 0; i < length(); i++) { 662 Method* m = unchecked_method_at(i); 663 if (m != NULL) { 664 tty->print(" (%5d) ", i); 665 m->access_flags().print_on(tty); 666 tty->print(" -- "); 667 m->print_name(tty); 668 tty->cr(); 669 } 670 } 671 } 672 673 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 674 void klassVtable::clear_vtable() { 675 for (int i = 0; i < _length; i++) table()[i].clear(); 676 } 677 678 bool klassVtable::is_initialized() { 679 return _length == 0 || table()[0].method() != NULL; 680 } 681 682 //----------------------------------------------------------------------------------------- 683 // Itable code 684 685 // Initialize a itableMethodEntry 686 void itableMethodEntry::initialize(Method* m) { 687 if (m == NULL) return; 688 689 _method = m; 690 } 691 692 klassItable::klassItable(instanceKlassHandle klass) { 693 _klass = klass; 694 695 if (klass->itable_length() > 0) { 696 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 697 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 698 // First offset entry points to the first method_entry 699 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset()); 700 intptr_t* end = klass->end_of_itable(); 701 702 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass(); 703 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 704 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 705 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 706 return; 707 } 708 } 709 710 // The length of the itable was either zero, or it has not yet been initialized. 711 _table_offset = 0; 712 _size_offset_table = 0; 713 _size_method_table = 0; 714 } 715 716 static int initialize_count = 0; 717 718 // Initialization 719 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 720 // Cannot be setup doing bootstrapping, interfaces don't have 721 // itables, and klass with only ones entry have empty itables 722 if (Universe::is_bootstrapping() || 723 _klass->is_interface() || 724 _klass->itable_length() == itableOffsetEntry::size()) return; 725 726 // There's alway an extra itable entry so we can null-terminate it. 727 guarantee(size_offset_table() >= 1, "too small"); 728 int num_interfaces = size_offset_table() - 1; 729 if (num_interfaces > 0) { 730 if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count, 731 _klass->name()->as_C_string()); 732 733 734 // Iterate through all interfaces 735 int i; 736 for(i = 0; i < num_interfaces; i++) { 737 itableOffsetEntry* ioe = offset_entry(i); 738 HandleMark hm(THREAD); 739 KlassHandle interf_h (THREAD, ioe->interface_klass()); 740 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable"); 741 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK); 742 } 743 744 } 745 // Check that the last entry is empty 746 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 747 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 748 } 749 750 751 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) { 752 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods(); 753 int nof_methods = methods->length(); 754 HandleMark hm; 755 KlassHandle klass = _klass; 756 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable"); 757 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader()); 758 int ime_num = 0; 759 760 // Skip first Method* if it is a class initializer 761 int i = methods->at(0)->is_static_initializer() ? 1 : 0; 762 763 // m, method_name, method_signature, klass reset each loop so they 764 // don't need preserving across check_signature_loaders call 765 // methods needs a handle in case of gc from check_signature_loaders 766 for(; i < nof_methods; i++) { 767 Method* m = methods->at(i); 768 Symbol* method_name = m->name(); 769 Symbol* method_signature = m->signature(); 770 771 // This is same code as in Linkresolver::lookup_instance_method_in_klasses 772 Method* target = klass->uncached_lookup_method(method_name, method_signature); 773 while (target != NULL && target->is_static()) { 774 // continue with recursive lookup through the superclass 775 Klass* super = target->method_holder()->super(); 776 target = (super == NULL) ? (Method*)NULL : super->uncached_lookup_method(method_name, method_signature); 777 } 778 if (target == NULL || !target->is_public() || target->is_abstract()) { 779 // Entry do not resolve. Leave it empty 780 } else { 781 // Entry did resolve, check loader constraints before initializing 782 // if checkconstraints requested 783 methodHandle target_h (THREAD, target); // preserve across gc 784 if (checkconstraints) { 785 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 786 if (method_holder_loader() != interface_loader()) { 787 ResourceMark rm(THREAD); 788 char* failed_type_name = 789 SystemDictionary::check_signature_loaders(method_signature, 790 method_holder_loader, 791 interface_loader, 792 true, CHECK); 793 if (failed_type_name != NULL) { 794 const char* msg = "loader constraint violation in interface " 795 "itable initialization: when resolving method \"%s\" the class" 796 " loader (instance of %s) of the current class, %s, " 797 "and the class loader (instance of %s) for interface " 798 "%s have different Class objects for the type %s " 799 "used in the signature"; 800 char* sig = target_h()->name_and_sig_as_C_string(); 801 const char* loader1 = SystemDictionary::loader_name(method_holder_loader()); 802 char* current = klass->name()->as_C_string(); 803 const char* loader2 = SystemDictionary::loader_name(interface_loader()); 804 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string(); 805 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 806 strlen(current) + strlen(loader2) + strlen(iface) + 807 strlen(failed_type_name); 808 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 809 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 810 iface, failed_type_name); 811 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 812 } 813 } 814 } 815 816 // ime may have moved during GC so recalculate address 817 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target_h()); 818 } 819 // Progress to next entry 820 ime_num++; 821 } 822 } 823 824 // Update entry for specific Method* 825 void klassItable::initialize_with_method(Method* m) { 826 itableMethodEntry* ime = method_entry(0); 827 for(int i = 0; i < _size_method_table; i++) { 828 if (ime->method() == m) { 829 ime->initialize(m); 830 } 831 ime++; 832 } 833 } 834 835 void klassItable::adjust_method_entries(Method** old_methods, Method** new_methods, 836 int methods_length, bool * trace_name_printed) { 837 // search the itable for uses of either obsolete or EMCP methods 838 for (int j = 0; j < methods_length; j++) { 839 Method* old_method = old_methods[j]; 840 Method* new_method = new_methods[j]; 841 itableMethodEntry* ime = method_entry(0); 842 843 // The itable can describe more than one interface and the same 844 // method signature can be specified by more than one interface. 845 // This means we have to do an exhaustive search to find all the 846 // old_method references. 847 for (int i = 0; i < _size_method_table; i++) { 848 if (ime->method() == old_method) { 849 ime->initialize(new_method); 850 851 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 852 if (!(*trace_name_printed)) { 853 // RC_TRACE_MESG macro has an embedded ResourceMark 854 RC_TRACE_MESG(("adjust: name=%s", 855 old_method->method_holder()->external_name())); 856 *trace_name_printed = true; 857 } 858 // RC_TRACE macro has an embedded ResourceMark 859 RC_TRACE(0x00200000, ("itable method update: %s(%s)", 860 new_method->name()->as_C_string(), 861 new_method->signature()->as_C_string())); 862 } 863 // cannot 'break' here; see for-loop comment above. 864 } 865 ime++; 866 } 867 } 868 } 869 870 // an itable should never contain old or obsolete methods 871 bool klassItable::check_no_old_or_obsolete_entries() { 872 itableMethodEntry* ime = method_entry(0); 873 for (int i = 0; i < _size_method_table; i++) { 874 Method* m = ime->method(); 875 if (m != NULL && 876 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 877 return false; 878 } 879 ime++; 880 } 881 return true; 882 } 883 884 void klassItable::dump_itable() { 885 itableMethodEntry* ime = method_entry(0); 886 tty->print_cr("itable dump --"); 887 for (int i = 0; i < _size_method_table; i++) { 888 Method* m = ime->method(); 889 if (m != NULL) { 890 tty->print(" (%5d) ", i); 891 m->access_flags().print_on(tty); 892 tty->print(" -- "); 893 m->print_name(tty); 894 tty->cr(); 895 } 896 ime++; 897 } 898 } 899 900 901 // Setup 902 class InterfaceVisiterClosure : public StackObj { 903 public: 904 virtual void doit(Klass* intf, int method_count) = 0; 905 }; 906 907 // Visit all interfaces with at-least one method (excluding <clinit>) 908 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 909 // Handle array argument 910 for(int i = 0; i < transitive_intf->length(); i++) { 911 Klass* intf = transitive_intf->at(i); 912 assert(intf->is_interface(), "sanity check"); 913 914 // Find no. of methods excluding a <clinit> 915 int method_count = InstanceKlass::cast(intf)->methods()->length(); 916 if (method_count > 0) { 917 Method* m = InstanceKlass::cast(intf)->methods()->at(0); 918 assert(m != NULL && m->is_method(), "sanity check"); 919 if (m->name() == vmSymbols::object_initializer_name()) { 920 method_count--; 921 } 922 } 923 924 // Only count interfaces with at least one method 925 if (method_count > 0) { 926 blk->doit(intf, method_count); 927 } 928 } 929 } 930 931 class CountInterfacesClosure : public InterfaceVisiterClosure { 932 private: 933 int _nof_methods; 934 int _nof_interfaces; 935 public: 936 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 937 938 int nof_methods() const { return _nof_methods; } 939 int nof_interfaces() const { return _nof_interfaces; } 940 941 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 942 }; 943 944 class SetupItableClosure : public InterfaceVisiterClosure { 945 private: 946 itableOffsetEntry* _offset_entry; 947 itableMethodEntry* _method_entry; 948 address _klass_begin; 949 public: 950 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 951 _klass_begin = klass_begin; 952 _offset_entry = offset_entry; 953 _method_entry = method_entry; 954 } 955 956 itableMethodEntry* method_entry() const { return _method_entry; } 957 958 void doit(Klass* intf, int method_count) { 959 int offset = ((address)_method_entry) - _klass_begin; 960 _offset_entry->initialize(intf, offset); 961 _offset_entry++; 962 _method_entry += method_count; 963 } 964 }; 965 966 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 967 // Count no of interfaces and total number of interface methods 968 CountInterfacesClosure cic; 969 visit_all_interfaces(transitive_interfaces, &cic); 970 971 // There's alway an extra itable entry so we can null-terminate it. 972 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 973 974 // Statistics 975 update_stats(itable_size * HeapWordSize); 976 977 return itable_size; 978 } 979 980 981 // Fill out offset table and interface klasses into the itable space 982 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) { 983 if (klass->itable_length() == 0) return; 984 assert(!klass->is_interface(), "Should have zero length itable"); 985 986 // Count no of interfaces and total number of interface methods 987 CountInterfacesClosure cic; 988 visit_all_interfaces(klass->transitive_interfaces(), &cic); 989 int nof_methods = cic.nof_methods(); 990 int nof_interfaces = cic.nof_interfaces(); 991 992 // Add one extra entry so we can null-terminate the table 993 nof_interfaces++; 994 995 assert(compute_itable_size(klass->transitive_interfaces()) == 996 calc_itable_size(nof_interfaces, nof_methods), 997 "mismatch calculation of itable size"); 998 999 // Fill-out offset table 1000 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1001 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1002 intptr_t* end = klass->end_of_itable(); 1003 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1004 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1005 1006 // Visit all interfaces and initialize itable offset table 1007 SetupItableClosure sic((address)klass(), ioe, ime); 1008 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1009 1010 #ifdef ASSERT 1011 ime = sic.method_entry(); 1012 oop* v = (oop*) klass->end_of_itable(); 1013 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1014 #endif 1015 } 1016 1017 1018 // m must be a method in an interface 1019 int klassItable::compute_itable_index(Method* m) { 1020 InstanceKlass* intf = m->method_holder(); 1021 assert(intf->is_interface(), "sanity check"); 1022 Array<Method*>* methods = intf->methods(); 1023 int index = 0; 1024 while(methods->at(index) != m) { 1025 index++; 1026 assert(index < methods->length(), "should find index for resolve_invoke"); 1027 } 1028 // Adjust for <clinit>, which is left out of table if first method 1029 if (methods->length() > 0 && methods->at(0)->is_static_initializer()) { 1030 index--; 1031 } 1032 return index; 1033 } 1034 1035 1036 // inverse to compute_itable_index 1037 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1038 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1039 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1040 1041 int index = itable_index; 1042 // Adjust for <clinit>, which is left out of table if first method 1043 if (methods->length() > 0 && methods->at(0)->is_static_initializer()) { 1044 index++; 1045 } 1046 1047 if (itable_index < 0 || index >= methods->length()) 1048 return NULL; // help caller defend against bad indexes 1049 1050 Method* m = methods->at(index); 1051 assert(compute_itable_index(m) == itable_index, "correct inverse"); 1052 1053 return m; 1054 } 1055 1056 void klassVtable::verify(outputStream* st, bool forced) { 1057 // make sure table is initialized 1058 if (!Universe::is_fully_initialized()) return; 1059 #ifndef PRODUCT 1060 // avoid redundant verifies 1061 if (!forced && _verify_count == Universe::verify_count()) return; 1062 _verify_count = Universe::verify_count(); 1063 #endif 1064 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 1065 oop* end_of_vtable = (oop *)&table()[_length]; 1066 if (end_of_vtable > end_of_obj) { 1067 fatal(err_msg("klass %s: klass object too short (vtable extends beyond " 1068 "end)", _klass->internal_name())); 1069 } 1070 1071 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1072 // verify consistency with superKlass vtable 1073 Klass* super = _klass->super(); 1074 if (super != NULL) { 1075 InstanceKlass* sk = InstanceKlass::cast(super); 1076 klassVtable* vt = sk->vtable(); 1077 for (int i = 0; i < vt->length(); i++) { 1078 verify_against(st, vt, i); 1079 } 1080 } 1081 } 1082 1083 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1084 vtableEntry* vte = &vt->table()[index]; 1085 if (vte->method()->name() != table()[index].method()->name() || 1086 vte->method()->signature() != table()[index].method()->signature()) { 1087 fatal("mismatched name/signature of vtable entries"); 1088 } 1089 } 1090 1091 #ifndef PRODUCT 1092 void klassVtable::print() { 1093 ResourceMark rm; 1094 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1095 for (int i = 0; i < length(); i++) { 1096 table()[i].print(); 1097 tty->cr(); 1098 } 1099 } 1100 #endif 1101 1102 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1103 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1104 assert(method() != NULL, "must have set method"); 1105 method()->verify(); 1106 // we sub_type, because it could be a miranda method 1107 if (!vt->klass()->is_subtype_of(method()->method_holder())) { 1108 #ifndef PRODUCT 1109 print(); 1110 #endif 1111 fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this)); 1112 } 1113 } 1114 1115 #ifndef PRODUCT 1116 1117 void vtableEntry::print() { 1118 ResourceMark rm; 1119 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1120 if (Verbose) { 1121 tty->print("m %#lx ", (address)method()); 1122 } 1123 } 1124 1125 class VtableStats : AllStatic { 1126 public: 1127 static int no_klasses; // # classes with vtables 1128 static int no_array_klasses; // # array classes 1129 static int no_instance_klasses; // # instanceKlasses 1130 static int sum_of_vtable_len; // total # of vtable entries 1131 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1132 static int fixed; // total fixed overhead in bytes 1133 static int filler; // overhead caused by filler bytes 1134 static int entries; // total bytes consumed by vtable entries 1135 static int array_entries; // total bytes consumed by array vtable entries 1136 1137 static void do_class(Klass* k) { 1138 Klass* kl = k; 1139 klassVtable* vt = kl->vtable(); 1140 if (vt == NULL) return; 1141 no_klasses++; 1142 if (kl->oop_is_instance()) { 1143 no_instance_klasses++; 1144 kl->array_klasses_do(do_class); 1145 } 1146 if (kl->oop_is_array()) { 1147 no_array_klasses++; 1148 sum_of_array_vtable_len += vt->length(); 1149 } 1150 sum_of_vtable_len += vt->length(); 1151 } 1152 1153 static void compute() { 1154 SystemDictionary::classes_do(do_class); 1155 fixed = no_klasses * oopSize; // vtable length 1156 // filler size is a conservative approximation 1157 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1158 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1159 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1160 } 1161 }; 1162 1163 int VtableStats::no_klasses = 0; 1164 int VtableStats::no_array_klasses = 0; 1165 int VtableStats::no_instance_klasses = 0; 1166 int VtableStats::sum_of_vtable_len = 0; 1167 int VtableStats::sum_of_array_vtable_len = 0; 1168 int VtableStats::fixed = 0; 1169 int VtableStats::filler = 0; 1170 int VtableStats::entries = 0; 1171 int VtableStats::array_entries = 0; 1172 1173 void klassVtable::print_statistics() { 1174 ResourceMark rm; 1175 HandleMark hm; 1176 VtableStats::compute(); 1177 tty->print_cr("vtable statistics:"); 1178 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1179 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1180 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1181 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1182 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1183 tty->print_cr("%6d bytes total", total); 1184 } 1185 1186 int klassItable::_total_classes; // Total no. of classes with itables 1187 long klassItable::_total_size; // Total no. of bytes used for itables 1188 1189 void klassItable::print_statistics() { 1190 tty->print_cr("itable statistics:"); 1191 tty->print_cr("%6d classes with itables", _total_classes); 1192 tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes); 1193 } 1194 1195 #endif // PRODUCT --- EOF ---