1 /* 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "classfile/vmSymbols.hpp" 28 #include "gc_implementation/shared/markSweep.inline.hpp" 29 #include "memory/gcLocker.hpp" 30 #include "memory/resourceArea.hpp" 31 #include "memory/universe.inline.hpp" 32 #include "oops/instanceKlass.hpp" 33 #include "oops/klassVtable.hpp" 34 #include "oops/method.hpp" 35 #include "oops/objArrayOop.hpp" 36 #include "oops/oop.inline.hpp" 37 #include "prims/jvmtiRedefineClassesTrace.hpp" 38 #include "runtime/arguments.hpp" 39 #include "runtime/handles.inline.hpp" 40 #include "utilities/copy.hpp" 41 42 inline InstanceKlass* klassVtable::ik() const { 43 Klass* k = _klass(); 44 assert(k->oop_is_instance(), "not an InstanceKlass"); 45 return (InstanceKlass*)k; 46 } 47 48 49 // this function computes the vtable size (including the size needed for miranda 50 // methods) and the number of miranda methods in this class. 51 // Note on Miranda methods: Let's say there is a class C that implements 52 // interface I, and none of C's superclasses implements I. 53 // Let's say there is an abstract method m in I that neither C 54 // nor any of its super classes implement (i.e there is no method of any access, 55 // with the same name and signature as m), then m is a Miranda method which is 56 // entered as a public abstract method in C's vtable. From then on it should 57 // treated as any other public method in C for method over-ride purposes. 58 void klassVtable::compute_vtable_size_and_num_mirandas( 59 int* vtable_length_ret, int* num_new_mirandas, 60 GrowableArray<Method*>* all_mirandas, Klass* super, 61 Array<Method*>* methods, AccessFlags class_flags, 62 Handle classloader, Symbol* classname, Array<Klass*>* local_interfaces, 63 TRAPS) { 64 No_Safepoint_Verifier nsv; 65 66 // set up default result values 67 int vtable_length = 0; 68 69 // start off with super's vtable length 70 InstanceKlass* sk = (InstanceKlass*)super; 71 vtable_length = super == NULL ? 0 : sk->vtable_length(); 72 73 // go thru each method in the methods table to see if it needs a new entry 74 int len = methods->length(); 75 for (int i = 0; i < len; i++) { 76 assert(methods->at(i)->is_method(), "must be a Method*"); 77 methodHandle mh(THREAD, methods->at(i)); 78 79 if (needs_new_vtable_entry(mh, super, classloader, classname, class_flags, THREAD)) { 80 vtable_length += vtableEntry::size(); // we need a new entry 81 } 82 } 83 84 GrowableArray<Method*> new_mirandas(20); 85 // compute the number of mirandas methods that must be added to the end 86 get_mirandas(&new_mirandas, all_mirandas, super, methods, NULL, local_interfaces); 87 *num_new_mirandas = new_mirandas.length(); 88 89 // Interfaces do not need interface methods in their vtables 90 // This includes miranda methods and during later processing, default methods 91 if (!class_flags.is_interface()) { 92 vtable_length += *num_new_mirandas * vtableEntry::size(); 93 } 94 95 if (Universe::is_bootstrapping() && vtable_length == 0) { 96 // array classes don't have their superclass set correctly during 97 // bootstrapping 98 vtable_length = Universe::base_vtable_size(); 99 } 100 101 if (super == NULL && !Universe::is_bootstrapping() && 102 vtable_length != Universe::base_vtable_size()) { 103 // Someone is attempting to redefine java.lang.Object incorrectly. The 104 // only way this should happen is from 105 // SystemDictionary::resolve_from_stream(), which will detect this later 106 // and throw a security exception. So don't assert here to let 107 // the exception occur. 108 vtable_length = Universe::base_vtable_size(); 109 } 110 assert(super != NULL || vtable_length == Universe::base_vtable_size(), 111 "bad vtable size for class Object"); 112 assert(vtable_length % vtableEntry::size() == 0, "bad vtable length"); 113 assert(vtable_length >= Universe::base_vtable_size(), "vtable too small"); 114 115 *vtable_length_ret = vtable_length; 116 } 117 118 int klassVtable::index_of(Method* m, int len) const { 119 assert(m->has_vtable_index(), "do not ask this of non-vtable methods"); 120 return m->vtable_index(); 121 } 122 123 // Copy super class's vtable to the first part (prefix) of this class's vtable, 124 // and return the number of entries copied. Expects that 'super' is the Java 125 // super class (arrays can have "array" super classes that must be skipped). 126 int klassVtable::initialize_from_super(KlassHandle super) { 127 if (super.is_null()) { 128 return 0; 129 } else { 130 // copy methods from superKlass 131 // can't inherit from array class, so must be InstanceKlass 132 assert(super->oop_is_instance(), "must be instance klass"); 133 InstanceKlass* sk = (InstanceKlass*)super(); 134 klassVtable* superVtable = sk->vtable(); 135 assert(superVtable->length() <= _length, "vtable too short"); 136 #ifdef ASSERT 137 superVtable->verify(tty, true); 138 #endif 139 superVtable->copy_vtable_to(table()); 140 #ifndef PRODUCT 141 if (PrintVtables && Verbose) { 142 ResourceMark rm; 143 tty->print_cr("copy vtable from %s to %s size %d", sk->internal_name(), klass()->internal_name(), _length); 144 } 145 #endif 146 return superVtable->length(); 147 } 148 } 149 150 // 151 // Revised lookup semantics introduced 1.3 (Kestrel beta) 152 void klassVtable::initialize_vtable(bool checkconstraints, TRAPS) { 153 154 // Note: Arrays can have intermediate array supers. Use java_super to skip them. 155 KlassHandle super (THREAD, klass()->java_super()); 156 int nofNewEntries = 0; 157 158 if (PrintVtables && !klass()->oop_is_array()) { 159 ResourceMark rm(THREAD); 160 tty->print_cr("Initializing: %s", _klass->name()->as_C_string()); 161 } 162 163 #ifdef ASSERT 164 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 165 oop* end_of_vtable = (oop*)&table()[_length]; 166 assert(end_of_vtable <= end_of_obj, "vtable extends beyond end"); 167 #endif 168 169 if (Universe::is_bootstrapping()) { 170 // just clear everything 171 for (int i = 0; i < _length; i++) table()[i].clear(); 172 return; 173 } 174 175 int super_vtable_len = initialize_from_super(super); 176 if (klass()->oop_is_array()) { 177 assert(super_vtable_len == _length, "arrays shouldn't introduce new methods"); 178 } else { 179 assert(_klass->oop_is_instance(), "must be InstanceKlass"); 180 181 Array<Method*>* methods = ik()->methods(); 182 int len = methods->length(); 183 int initialized = super_vtable_len; 184 185 // Check each of this class's methods against super; 186 // if override, replace in copy of super vtable, otherwise append to end 187 for (int i = 0; i < len; i++) { 188 // update_inherited_vtable can stop for gc - ensure using handles 189 HandleMark hm(THREAD); 190 assert(methods->at(i)->is_method(), "must be a Method*"); 191 methodHandle mh(THREAD, methods->at(i)); 192 193 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, -1, checkconstraints, CHECK); 194 195 if (needs_new_entry) { 196 put_method_at(mh(), initialized); 197 mh()->set_vtable_index(initialized); // set primary vtable index 198 initialized++; 199 } 200 } 201 202 // update vtable with default_methods 203 Array<Method*>* default_methods = ik()->default_methods(); 204 if (default_methods != NULL) { 205 len = default_methods->length(); 206 if (len > 0) { 207 Array<int>* def_vtable_indices = NULL; 208 if ((def_vtable_indices = ik()->default_vtable_indices()) == NULL) { 209 def_vtable_indices = ik()->create_new_default_vtable_indices(len, CHECK); 210 } else { 211 assert(def_vtable_indices->length() == len, "reinit vtable len?"); 212 } 213 for (int i = 0; i < len; i++) { 214 HandleMark hm(THREAD); 215 assert(default_methods->at(i)->is_method(), "must be a Method*"); 216 methodHandle mh(THREAD, default_methods->at(i)); 217 218 bool needs_new_entry = update_inherited_vtable(ik(), mh, super_vtable_len, i, checkconstraints, CHECK); 219 220 // needs new entry 221 if (needs_new_entry) { 222 put_method_at(mh(), initialized); 223 def_vtable_indices->at_put(i, initialized); //set vtable index 224 initialized++; 225 } 226 } 227 } 228 } 229 230 // add miranda methods; it will also return the updated initialized 231 // Interfaces do not need interface methods in their vtables 232 // This includes miranda methods and during later processing, default methods 233 if (!ik()->is_interface()) { 234 initialized = fill_in_mirandas(initialized); 235 } 236 237 // In class hierarchies where the accessibility is not increasing (i.e., going from private -> 238 // package_private -> public/protected), the vtable might actually be smaller than our initial 239 // calculation. 240 assert(initialized <= _length, "vtable initialization failed"); 241 for(;initialized < _length; initialized++) { 242 put_method_at(NULL, initialized); 243 } 244 NOT_PRODUCT(verify(tty, true)); 245 } 246 } 247 248 // Called for cases where a method does not override its superclass' vtable entry 249 // For bytecodes not produced by javac together it is possible that a method does not override 250 // the superclass's method, but might indirectly override a super-super class's vtable entry 251 // If none found, return a null superk, else return the superk of the method this does override 252 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method, 253 int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) { 254 InstanceKlass* superk = initialsuper; 255 while (superk != NULL && superk->super() != NULL) { 256 InstanceKlass* supersuperklass = InstanceKlass::cast(superk->super()); 257 klassVtable* ssVtable = supersuperklass->vtable(); 258 if (vtable_index < ssVtable->length()) { 259 Method* super_method = ssVtable->method_at(vtable_index); 260 #ifndef PRODUCT 261 Symbol* name= target_method()->name(); 262 Symbol* signature = target_method()->signature(); 263 assert(super_method->name() == name && super_method->signature() == signature, "vtable entry name/sig mismatch"); 264 #endif 265 if (supersuperklass->is_override(super_method, target_loader, target_classname, THREAD)) { 266 #ifndef PRODUCT 267 if (PrintVtables && Verbose) { 268 ResourceMark rm(THREAD); 269 char* sig = target_method()->name_and_sig_as_C_string(); 270 tty->print("transitive overriding superclass %s with %s::%s index %d, original flags: ", 271 supersuperklass->internal_name(), 272 _klass->internal_name(), sig, vtable_index); 273 super_method->access_flags().print_on(tty); 274 if (super_method->is_default_method()) { 275 tty->print("default "); 276 } 277 tty->print("overriders flags: "); 278 target_method->access_flags().print_on(tty); 279 if (target_method->is_default_method()) { 280 tty->print("default "); 281 } 282 } 283 #endif /*PRODUCT*/ 284 break; // return found superk 285 } 286 } else { 287 // super class has no vtable entry here, stop transitive search 288 superk = (InstanceKlass*)NULL; 289 break; 290 } 291 // if no override found yet, continue to search up 292 superk = InstanceKlass::cast(superk->super()); 293 } 294 295 return superk; 296 } 297 298 // Update child's copy of super vtable for overrides 299 // OR return true if a new vtable entry is required. 300 // Only called for InstanceKlass's, i.e. not for arrays 301 // If that changed, could not use _klass as handle for klass 302 bool klassVtable::update_inherited_vtable(InstanceKlass* klass, methodHandle target_method, 303 int super_vtable_len, int default_index, 304 bool checkconstraints, TRAPS) { 305 ResourceMark rm; 306 bool allocate_new = true; 307 assert(klass->oop_is_instance(), "must be InstanceKlass"); 308 309 Array<int>* def_vtable_indices = NULL; 310 bool is_default = false; 311 // default methods are concrete methods in superinterfaces which are added to the vtable 312 // with their real method_holder 313 // Since vtable and itable indices share the same storage, don't touch 314 // the default method's real vtable/itable index 315 // default_vtable_indices stores the vtable value relative to this inheritor 316 if (default_index >= 0 ) { 317 is_default = true; 318 def_vtable_indices = klass->default_vtable_indices(); 319 assert(def_vtable_indices != NULL, "def vtable alloc?"); 320 assert(default_index <= def_vtable_indices->length(), "def vtable len?"); 321 } else { 322 assert(klass == target_method()->method_holder(), "caller resp."); 323 // Initialize the method's vtable index to "nonvirtual". 324 // If we allocate a vtable entry, we will update it to a non-negative number. 325 target_method()->set_vtable_index(Method::nonvirtual_vtable_index); 326 } 327 328 // Static and <init> methods are never in 329 if (target_method()->is_static() || target_method()->name() == vmSymbols::object_initializer_name()) { 330 return false; 331 } 332 333 if (target_method->is_final_method(klass->access_flags())) { 334 // a final method never needs a new entry; final methods can be statically 335 // resolved and they have to be present in the vtable only if they override 336 // a super's method, in which case they re-use its entry 337 allocate_new = false; 338 } else if (klass->is_interface()) { 339 allocate_new = false; // see note below in needs_new_vtable_entry 340 // An interface never allocates new vtable slots, only inherits old ones. 341 // This method will either be assigned its own itable index later, 342 // or be assigned an inherited vtable index in the loop below. 343 // default methods inherited by classes store their vtable indices 344 // in the inheritor's default_vtable_indices 345 // default methods inherited by interfaces may already have a 346 // valid itable index, if so, don't change it 347 // overpass methods in an interface will be assigned an itable index later 348 // by an inheriting class 349 if (!is_default || !target_method()->has_itable_index()) { 350 target_method()->set_vtable_index(Method::pending_itable_index); 351 } 352 } 353 354 // we need a new entry if there is no superclass 355 if (klass->super() == NULL) { 356 return allocate_new; 357 } 358 359 // private methods in classes always have a new entry in the vtable 360 // specification interpretation since classic has 361 // private methods not overriding 362 // JDK8 adds private methods in interfaces which require invokespecial 363 if (target_method()->is_private()) { 364 return allocate_new; 365 } 366 367 // search through the vtable and update overridden entries 368 // Since check_signature_loaders acquires SystemDictionary_lock 369 // which can block for gc, once we are in this loop, use handles 370 // For classfiles built with >= jdk7, we now look for transitive overrides 371 372 Symbol* name = target_method()->name(); 373 Symbol* signature = target_method()->signature(); 374 375 KlassHandle target_klass(THREAD, target_method()->method_holder()); 376 if (target_klass == NULL) { 377 target_klass = _klass; 378 } 379 380 Handle target_loader(THREAD, target_klass->class_loader()); 381 382 Symbol* target_classname = target_klass->name(); 383 for(int i = 0; i < super_vtable_len; i++) { 384 Method* super_method = method_at(i); 385 // Check if method name matches 386 if (super_method->name() == name && super_method->signature() == signature) { 387 388 // get super_klass for method_holder for the found method 389 InstanceKlass* super_klass = super_method->method_holder(); 390 391 if (is_default 392 || ((super_klass->is_override(super_method, target_loader, target_classname, THREAD)) 393 || ((klass->major_version() >= VTABLE_TRANSITIVE_OVERRIDE_VERSION) 394 && ((super_klass = find_transitive_override(super_klass, 395 target_method, i, target_loader, 396 target_classname, THREAD)) 397 != (InstanceKlass*)NULL)))) 398 { 399 // overriding, so no new entry 400 allocate_new = false; 401 402 if (checkconstraints) { 403 // Override vtable entry if passes loader constraint check 404 // if loader constraint checking requested 405 // No need to visit his super, since he and his super 406 // have already made any needed loader constraints. 407 // Since loader constraints are transitive, it is enough 408 // to link to the first super, and we get all the others. 409 Handle super_loader(THREAD, super_klass->class_loader()); 410 411 if (target_loader() != super_loader()) { 412 ResourceMark rm(THREAD); 413 Symbol* failed_type_symbol = 414 SystemDictionary::check_signature_loaders(signature, target_loader, 415 super_loader, true, 416 CHECK_(false)); 417 if (failed_type_symbol != NULL) { 418 const char* msg = "loader constraint violation: when resolving " 419 "overridden method \"%s\" the class loader (instance" 420 " of %s) of the current class, %s, and its superclass loader " 421 "(instance of %s), have different Class objects for the type " 422 "%s used in the signature"; 423 char* sig = target_method()->name_and_sig_as_C_string(); 424 const char* loader1 = SystemDictionary::loader_name(target_loader()); 425 char* current = target_klass->name()->as_C_string(); 426 const char* loader2 = SystemDictionary::loader_name(super_loader()); 427 char* failed_type_name = failed_type_symbol->as_C_string(); 428 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 429 strlen(current) + strlen(loader2) + strlen(failed_type_name); 430 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 431 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 432 failed_type_name); 433 THROW_MSG_(vmSymbols::java_lang_LinkageError(), buf, false); 434 } 435 } 436 } 437 438 put_method_at(target_method(), i); 439 if (!is_default) { 440 target_method()->set_vtable_index(i); 441 } else { 442 if (def_vtable_indices != NULL) { 443 def_vtable_indices->at_put(default_index, i); 444 } 445 assert(super_method->is_default_method() || super_method->is_overpass() 446 || super_method->is_abstract(), "default override error"); 447 } 448 449 450 #ifndef PRODUCT 451 if (PrintVtables && Verbose) { 452 ResourceMark rm(THREAD); 453 char* sig = target_method()->name_and_sig_as_C_string(); 454 tty->print("overriding with %s::%s index %d, original flags: ", 455 target_klass->internal_name(), sig, i); 456 super_method->access_flags().print_on(tty); 457 if (super_method->is_default_method()) { 458 tty->print("default "); 459 } 460 if (super_method->is_overpass()) { 461 tty->print("overpass"); 462 } 463 tty->print("overriders flags: "); 464 target_method->access_flags().print_on(tty); 465 if (target_method->is_default_method()) { 466 tty->print("default "); 467 } 468 if (target_method->is_overpass()) { 469 tty->print("overpass"); 470 } 471 tty->cr(); 472 } 473 #endif /*PRODUCT*/ 474 } else { 475 // allocate_new = true; default. We might override one entry, 476 // but not override another. Once we override one, not need new 477 #ifndef PRODUCT 478 if (PrintVtables && Verbose) { 479 ResourceMark rm(THREAD); 480 char* sig = target_method()->name_and_sig_as_C_string(); 481 tty->print("NOT overriding with %s::%s index %d, original flags: ", 482 target_klass->internal_name(), sig,i); 483 super_method->access_flags().print_on(tty); 484 if (super_method->is_default_method()) { 485 tty->print("default "); 486 } 487 if (super_method->is_overpass()) { 488 tty->print("overpass"); 489 } 490 tty->print("overriders flags: "); 491 target_method->access_flags().print_on(tty); 492 if (target_method->is_default_method()) { 493 tty->print("default "); 494 } 495 if (target_method->is_overpass()) { 496 tty->print("overpass"); 497 } 498 tty->cr(); 499 } 500 #endif /*PRODUCT*/ 501 } 502 } 503 } 504 return allocate_new; 505 } 506 507 void klassVtable::put_method_at(Method* m, int index) { 508 #ifndef PRODUCT 509 if (PrintVtables && Verbose) { 510 ResourceMark rm; 511 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 512 tty->print("adding %s at index %d, flags: ", sig, index); 513 if (m != NULL) { 514 m->access_flags().print_on(tty); 515 if (m->is_default_method()) { 516 tty->print("default "); 517 } 518 if (m->is_overpass()) { 519 tty->print("overpass"); 520 } 521 } 522 tty->cr(); 523 } 524 #endif 525 table()[index].set(m); 526 } 527 528 // Find out if a method "m" with superclass "super", loader "classloader" and 529 // name "classname" needs a new vtable entry. Let P be a class package defined 530 // by "classloader" and "classname". 531 // NOTE: The logic used here is very similar to the one used for computing 532 // the vtables indices for a method. We cannot directly use that function because, 533 // we allocate the InstanceKlass at load time, and that requires that the 534 // superclass has been loaded. 535 // However, the vtable entries are filled in at link time, and therefore 536 // the superclass' vtable may not yet have been filled in. 537 bool klassVtable::needs_new_vtable_entry(methodHandle target_method, 538 Klass* super, 539 Handle classloader, 540 Symbol* classname, 541 AccessFlags class_flags, 542 TRAPS) { 543 if (class_flags.is_interface()) { 544 // Interfaces do not use vtables, so there is no point to assigning 545 // a vtable index to any of their methods. If we refrain from doing this, 546 // we can use Method::_vtable_index to hold the itable index 547 return false; 548 } 549 550 if (target_method->is_final_method(class_flags) || 551 // a final method never needs a new entry; final methods can be statically 552 // resolved and they have to be present in the vtable only if they override 553 // a super's method, in which case they re-use its entry 554 (target_method()->is_static()) || 555 // static methods don't need to be in vtable 556 (target_method()->name() == vmSymbols::object_initializer_name()) 557 // <init> is never called dynamically-bound 558 ) { 559 return false; 560 } 561 562 // Concrete interface methods do not need new entries, they override 563 // abstract method entries using default inheritance rules 564 if (target_method()->method_holder() != NULL && 565 target_method()->method_holder()->is_interface() && 566 !target_method()->is_abstract() ) { 567 return false; 568 } 569 570 // we need a new entry if there is no superclass 571 if (super == NULL) { 572 return true; 573 } 574 575 // private methods in classes always have a new entry in the vtable 576 // specification interpretation since classic has 577 // private methods not overriding 578 // JDK8 adds private methods in interfaces which require invokespecial 579 if (target_method()->is_private()) { 580 return true; 581 } 582 583 // search through the super class hierarchy to see if we need 584 // a new entry 585 ResourceMark rm; 586 Symbol* name = target_method()->name(); 587 Symbol* signature = target_method()->signature(); 588 Klass* k = super; 589 Method* super_method = NULL; 590 InstanceKlass *holder = NULL; 591 Method* recheck_method = NULL; 592 while (k != NULL) { 593 // lookup through the hierarchy for a method with matching name and sign. 594 super_method = InstanceKlass::cast(k)->lookup_method(name, signature); 595 if (super_method == NULL) { 596 break; // we still have to search for a matching miranda method 597 } 598 // get the class holding the matching method 599 // make sure you use that class for is_override 600 InstanceKlass* superk = super_method->method_holder(); 601 // we want only instance method matches 602 // pretend private methods are not in the super vtable 603 // since we do override around them: e.g. a.m pub/b.m private/c.m pub, 604 // ignore private, c.m pub does override a.m pub 605 // For classes that were not javac'd together, we also do transitive overriding around 606 // methods that have less accessibility 607 if ((!super_method->is_static()) && 608 (!super_method->is_private())) { 609 if (superk->is_override(super_method, classloader, classname, THREAD)) { 610 return false; 611 // else keep looking for transitive overrides 612 } 613 } 614 615 // Start with lookup result and continue to search up 616 k = superk->super(); // haven't found an override match yet; continue to look 617 } 618 619 // if the target method is public or protected it may have a matching 620 // miranda method in the super, whose entry it should re-use. 621 // Actually, to handle cases that javac would not generate, we need 622 // this check for all access permissions. 623 InstanceKlass *sk = InstanceKlass::cast(super); 624 if (sk->has_miranda_methods()) { 625 if (sk->lookup_method_in_all_interfaces(name, signature, false) != NULL) { 626 return false; // found a matching miranda; we do not need a new entry 627 } 628 } 629 return true; // found no match; we need a new entry 630 } 631 632 // Support for miranda methods 633 634 // get the vtable index of a miranda method with matching "name" and "signature" 635 int klassVtable::index_of_miranda(Symbol* name, Symbol* signature) { 636 // search from the bottom, might be faster 637 for (int i = (length() - 1); i >= 0; i--) { 638 Method* m = table()[i].method(); 639 if (is_miranda_entry_at(i) && 640 m->name() == name && m->signature() == signature) { 641 return i; 642 } 643 } 644 return Method::invalid_vtable_index; 645 } 646 647 // check if an entry at an index is miranda 648 // requires that method m at entry be declared ("held") by an interface. 649 bool klassVtable::is_miranda_entry_at(int i) { 650 Method* m = method_at(i); 651 Klass* method_holder = m->method_holder(); 652 InstanceKlass *mhk = InstanceKlass::cast(method_holder); 653 654 // miranda methods are public abstract instance interface methods in a class's vtable 655 if (mhk->is_interface()) { 656 assert(m->is_public(), "should be public"); 657 assert(ik()->implements_interface(method_holder) , "this class should implement the interface"); 658 // the search could find a miranda or a default method 659 if (is_miranda(m, ik()->methods(), ik()->default_methods(), ik()->super())) { 660 return true; 661 } 662 } 663 return false; 664 } 665 666 // check if a method is a miranda method, given a class's methods table, 667 // its default_method table and its super 668 // Miranda methods are calculated twice: 669 // first: before vtable size calculation: including abstract and default 670 // This is seen by default method creation 671 // Second: recalculated during vtable initialization: only abstract 672 // This is seen by link resolution and selection. 673 // "miranda" means not static, not defined by this class. 674 // private methods in interfaces do not belong in the miranda list. 675 // the caller must make sure that the method belongs to an interface implemented by the class 676 // Miranda methods only include public interface instance methods 677 // Not private methods, not static methods, not default == concrete abstract 678 // Miranda methods also do not include overpass methods in interfaces 679 bool klassVtable::is_miranda(Method* m, Array<Method*>* class_methods, 680 Array<Method*>* default_methods, Klass* super) { 681 if (m->is_static() || m->is_private() || m->is_overpass()) { 682 return false; 683 } 684 Symbol* name = m->name(); 685 Symbol* signature = m->signature(); 686 687 if (InstanceKlass::find_instance_method(class_methods, name, signature) == NULL) { 688 // did not find it in the method table of the current class 689 if ((default_methods == NULL) || 690 InstanceKlass::find_method(default_methods, name, signature) == NULL) { 691 if (super == NULL) { 692 // super doesn't exist 693 return true; 694 } 695 696 Method* mo = InstanceKlass::cast(super)->lookup_method(name, signature); 697 while (mo != NULL && mo->access_flags().is_static() 698 && mo->method_holder() != NULL 699 && mo->method_holder()->super() != NULL) 700 { 701 mo = mo->method_holder()->super()->uncached_lookup_method(name, signature); 702 } 703 if (mo == NULL || mo->access_flags().is_private() ) { 704 // super class hierarchy does not implement it or protection is different 705 return true; 706 } 707 } 708 } 709 710 return false; 711 } 712 713 // Scans current_interface_methods for miranda methods that do not 714 // already appear in new_mirandas, or default methods, and are also not defined-and-non-private 715 // in super (superclass). These mirandas are added to all_mirandas if it is 716 // not null; in addition, those that are not duplicates of miranda methods 717 // inherited by super from its interfaces are added to new_mirandas. 718 // Thus, new_mirandas will be the set of mirandas that this class introduces, 719 // all_mirandas will be the set of all mirandas applicable to this class 720 // including all defined in superclasses. 721 void klassVtable::add_new_mirandas_to_lists( 722 GrowableArray<Method*>* new_mirandas, GrowableArray<Method*>* all_mirandas, 723 Array<Method*>* current_interface_methods, Array<Method*>* class_methods, 724 Array<Method*>* default_methods, Klass* super) { 725 726 // iterate thru the current interface's method to see if it a miranda 727 int num_methods = current_interface_methods->length(); 728 for (int i = 0; i < num_methods; i++) { 729 Method* im = current_interface_methods->at(i); 730 bool is_duplicate = false; 731 int num_of_current_mirandas = new_mirandas->length(); 732 // check for duplicate mirandas in different interfaces we implement 733 for (int j = 0; j < num_of_current_mirandas; j++) { 734 Method* miranda = new_mirandas->at(j); 735 if ((im->name() == miranda->name()) && 736 (im->signature() == miranda->signature())) { 737 is_duplicate = true; 738 break; 739 } 740 } 741 742 if (!is_duplicate) { // we don't want duplicate miranda entries in the vtable 743 if (is_miranda(im, class_methods, default_methods, super)) { // is it a miranda at all? 744 InstanceKlass *sk = InstanceKlass::cast(super); 745 // check if it is a duplicate of a super's miranda 746 if (sk->lookup_method_in_all_interfaces(im->name(), im->signature(), false) == NULL) { 747 new_mirandas->append(im); 748 } 749 if (all_mirandas != NULL) { 750 all_mirandas->append(im); 751 } 752 } 753 } 754 } 755 } 756 757 void klassVtable::get_mirandas(GrowableArray<Method*>* new_mirandas, 758 GrowableArray<Method*>* all_mirandas, 759 Klass* super, Array<Method*>* class_methods, 760 Array<Method*>* default_methods, 761 Array<Klass*>* local_interfaces) { 762 assert((new_mirandas->length() == 0) , "current mirandas must be 0"); 763 764 // iterate thru the local interfaces looking for a miranda 765 int num_local_ifs = local_interfaces->length(); 766 for (int i = 0; i < num_local_ifs; i++) { 767 InstanceKlass *ik = InstanceKlass::cast(local_interfaces->at(i)); 768 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 769 ik->methods(), class_methods, 770 default_methods, super); 771 // iterate thru each local's super interfaces 772 Array<Klass*>* super_ifs = ik->transitive_interfaces(); 773 int num_super_ifs = super_ifs->length(); 774 for (int j = 0; j < num_super_ifs; j++) { 775 InstanceKlass *sik = InstanceKlass::cast(super_ifs->at(j)); 776 add_new_mirandas_to_lists(new_mirandas, all_mirandas, 777 sik->methods(), class_methods, 778 default_methods, super); 779 } 780 } 781 } 782 783 // Discover miranda methods ("miranda" = "interface abstract, no binding"), 784 // and append them into the vtable starting at index initialized, 785 // return the new value of initialized. 786 // Miranda methods use vtable entries, but do not get assigned a vtable_index 787 // The vtable_index is discovered by searching from the end of the vtable 788 int klassVtable::fill_in_mirandas(int initialized) { 789 GrowableArray<Method*> mirandas(20); 790 get_mirandas(&mirandas, NULL, ik()->super(), ik()->methods(), 791 ik()->default_methods(), ik()->local_interfaces()); 792 for (int i = 0; i < mirandas.length(); i++) { 793 if (PrintVtables && Verbose) { 794 Method* meth = mirandas.at(i); 795 ResourceMark rm(Thread::current()); 796 if (meth != NULL) { 797 char* sig = meth->name_and_sig_as_C_string(); 798 tty->print("fill in mirandas with %s index %d, flags: ", 799 sig, initialized); 800 meth->access_flags().print_on(tty); 801 if (meth->is_default_method()) { 802 tty->print("default "); 803 } 804 tty->cr(); 805 } 806 } 807 put_method_at(mirandas.at(i), initialized); 808 ++initialized; 809 } 810 return initialized; 811 } 812 813 // Copy this class's vtable to the vtable beginning at start. 814 // Used to copy superclass vtable to prefix of subclass's vtable. 815 void klassVtable::copy_vtable_to(vtableEntry* start) { 816 Copy::disjoint_words((HeapWord*)table(), (HeapWord*)start, _length * vtableEntry::size()); 817 } 818 819 #if INCLUDE_JVMTI 820 bool klassVtable::adjust_default_method(int vtable_index, Method* old_method, Method* new_method) { 821 // If old_method is default, find this vtable index in default_vtable_indices 822 // and replace that method in the _default_methods list 823 bool updated = false; 824 825 Array<Method*>* default_methods = ik()->default_methods(); 826 if (default_methods != NULL) { 827 int len = default_methods->length(); 828 for (int idx = 0; idx < len; idx++) { 829 if (vtable_index == ik()->default_vtable_indices()->at(idx)) { 830 if (default_methods->at(idx) == old_method) { 831 default_methods->at_put(idx, new_method); 832 updated = true; 833 } 834 break; 835 } 836 } 837 } 838 return updated; 839 } 840 void klassVtable::adjust_method_entries(Method** old_methods, Method** new_methods, 841 int methods_length, bool * trace_name_printed) { 842 // search the vtable for uses of either obsolete or EMCP methods 843 for (int j = 0; j < methods_length; j++) { 844 Method* old_method = old_methods[j]; 845 Method* new_method = new_methods[j]; 846 847 // In the vast majority of cases we could get the vtable index 848 // by using: old_method->vtable_index() 849 // However, there are rare cases, eg. sun.awt.X11.XDecoratedPeer.getX() 850 // in sun.awt.X11.XFramePeer where methods occur more than once in the 851 // vtable, so, alas, we must do an exhaustive search. 852 for (int index = 0; index < length(); index++) { 853 if (unchecked_method_at(index) == old_method) { 854 put_method_at(new_method, index); 855 // For default methods, need to update the _default_methods array 856 // which can only have one method entry for a given signature 857 bool updated_default = false; 858 if (old_method->is_default_method()) { 859 updated_default = adjust_default_method(index, old_method, new_method); 860 } 861 862 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 863 if (!(*trace_name_printed)) { 864 // RC_TRACE_MESG macro has an embedded ResourceMark 865 RC_TRACE_MESG(("adjust: klassname=%s for methods from name=%s", 866 klass()->external_name(), 867 old_method->method_holder()->external_name())); 868 *trace_name_printed = true; 869 } 870 // RC_TRACE macro has an embedded ResourceMark 871 RC_TRACE(0x00100000, ("vtable method update: %s(%s), updated default = %s", 872 new_method->name()->as_C_string(), 873 new_method->signature()->as_C_string(), 874 updated_default ? "true" : "false")); 875 } 876 // cannot 'break' here; see for-loop comment above. 877 } 878 } 879 } 880 } 881 882 // a vtable should never contain old or obsolete methods 883 bool klassVtable::check_no_old_or_obsolete_entries() { 884 for (int i = 0; i < length(); i++) { 885 Method* m = unchecked_method_at(i); 886 if (m != NULL && 887 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 888 return false; 889 } 890 } 891 return true; 892 } 893 894 void klassVtable::dump_vtable() { 895 tty->print_cr("vtable dump --"); 896 for (int i = 0; i < length(); i++) { 897 Method* m = unchecked_method_at(i); 898 if (m != NULL) { 899 tty->print(" (%5d) ", i); 900 m->access_flags().print_on(tty); 901 if (m->is_default_method()) { 902 tty->print("default "); 903 } 904 if (m->is_overpass()) { 905 tty->print("overpass"); 906 } 907 tty->print(" -- "); 908 m->print_name(tty); 909 tty->cr(); 910 } 911 } 912 } 913 #endif // INCLUDE_JVMTI 914 915 // CDS/RedefineClasses support - clear vtables so they can be reinitialized 916 void klassVtable::clear_vtable() { 917 for (int i = 0; i < _length; i++) table()[i].clear(); 918 } 919 920 bool klassVtable::is_initialized() { 921 return _length == 0 || table()[0].method() != NULL; 922 } 923 924 //----------------------------------------------------------------------------------------- 925 // Itable code 926 927 // Initialize a itableMethodEntry 928 void itableMethodEntry::initialize(Method* m) { 929 if (m == NULL) return; 930 931 _method = m; 932 } 933 934 klassItable::klassItable(instanceKlassHandle klass) { 935 _klass = klass; 936 937 if (klass->itable_length() > 0) { 938 itableOffsetEntry* offset_entry = (itableOffsetEntry*)klass->start_of_itable(); 939 if (offset_entry != NULL && offset_entry->interface_klass() != NULL) { // Check that itable is initialized 940 // First offset entry points to the first method_entry 941 intptr_t* method_entry = (intptr_t *)(((address)klass()) + offset_entry->offset()); 942 intptr_t* end = klass->end_of_itable(); 943 944 _table_offset = (intptr_t*)offset_entry - (intptr_t*)klass(); 945 _size_offset_table = (method_entry - ((intptr_t*)offset_entry)) / itableOffsetEntry::size(); 946 _size_method_table = (end - method_entry) / itableMethodEntry::size(); 947 assert(_table_offset >= 0 && _size_offset_table >= 0 && _size_method_table >= 0, "wrong computation"); 948 return; 949 } 950 } 951 952 // The length of the itable was either zero, or it has not yet been initialized. 953 _table_offset = 0; 954 _size_offset_table = 0; 955 _size_method_table = 0; 956 } 957 958 static int initialize_count = 0; 959 960 // Initialization 961 void klassItable::initialize_itable(bool checkconstraints, TRAPS) { 962 if (_klass->is_interface()) { 963 // This needs to go after vtable indices are assigned but 964 // before implementors need to know the number of itable indices. 965 assign_itable_indices_for_interface(_klass()); 966 } 967 968 // Cannot be setup doing bootstrapping, interfaces don't have 969 // itables, and klass with only ones entry have empty itables 970 if (Universe::is_bootstrapping() || 971 _klass->is_interface() || 972 _klass->itable_length() == itableOffsetEntry::size()) return; 973 974 // There's alway an extra itable entry so we can null-terminate it. 975 guarantee(size_offset_table() >= 1, "too small"); 976 int num_interfaces = size_offset_table() - 1; 977 if (num_interfaces > 0) { 978 if (TraceItables) tty->print_cr("%3d: Initializing itables for %s", ++initialize_count, 979 _klass->name()->as_C_string()); 980 981 982 // Iterate through all interfaces 983 int i; 984 for(i = 0; i < num_interfaces; i++) { 985 itableOffsetEntry* ioe = offset_entry(i); 986 HandleMark hm(THREAD); 987 KlassHandle interf_h (THREAD, ioe->interface_klass()); 988 assert(interf_h() != NULL && ioe->offset() != 0, "bad offset entry in itable"); 989 initialize_itable_for_interface(ioe->offset(), interf_h, checkconstraints, CHECK); 990 } 991 992 } 993 // Check that the last entry is empty 994 itableOffsetEntry* ioe = offset_entry(size_offset_table() - 1); 995 guarantee(ioe->interface_klass() == NULL && ioe->offset() == 0, "terminator entry missing"); 996 } 997 998 999 inline bool interface_method_needs_itable_index(Method* m) { 1000 if (m->is_static()) return false; // e.g., Stream.empty 1001 if (m->is_initializer()) return false; // <init> or <clinit> 1002 // If an interface redeclares a method from java.lang.Object, 1003 // it should already have a vtable index, don't touch it. 1004 // e.g., CharSequence.toString (from initialize_vtable) 1005 // if (m->has_vtable_index()) return false; // NO! 1006 return true; 1007 } 1008 1009 int klassItable::assign_itable_indices_for_interface(Klass* klass) { 1010 // an interface does not have an itable, but its methods need to be numbered 1011 if (TraceItables) tty->print_cr("%3d: Initializing itable for interface %s", ++initialize_count, 1012 klass->name()->as_C_string()); 1013 Array<Method*>* methods = InstanceKlass::cast(klass)->methods(); 1014 int nof_methods = methods->length(); 1015 int ime_num = 0; 1016 for (int i = 0; i < nof_methods; i++) { 1017 Method* m = methods->at(i); 1018 if (interface_method_needs_itable_index(m)) { 1019 assert(!m->is_final_method(), "no final interface methods"); 1020 // If m is already assigned a vtable index, do not disturb it. 1021 if (TraceItables && Verbose) { 1022 ResourceMark rm; 1023 const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>"; 1024 if (m->has_vtable_index()) { 1025 tty->print("itable index %d for method: %s, flags: ", m->vtable_index(), sig); 1026 } else { 1027 tty->print("itable index %d for method: %s, flags: ", ime_num, sig); 1028 } 1029 if (m != NULL) { 1030 m->access_flags().print_on(tty); 1031 if (m->is_default_method()) { 1032 tty->print("default "); 1033 } 1034 if (m->is_overpass()) { 1035 tty->print("overpass"); 1036 } 1037 } 1038 tty->cr(); 1039 } 1040 if (!m->has_vtable_index()) { 1041 assert(m->vtable_index() == Method::pending_itable_index, "set by initialize_vtable"); 1042 m->set_itable_index(ime_num); 1043 // Progress to next itable entry 1044 ime_num++; 1045 } 1046 } 1047 } 1048 assert(ime_num == method_count_for_interface(klass), "proper sizing"); 1049 return ime_num; 1050 } 1051 1052 int klassItable::method_count_for_interface(Klass* interf) { 1053 assert(interf->oop_is_instance(), "must be"); 1054 assert(interf->is_interface(), "must be"); 1055 Array<Method*>* methods = InstanceKlass::cast(interf)->methods(); 1056 int nof_methods = methods->length(); 1057 while (nof_methods > 0) { 1058 Method* m = methods->at(nof_methods-1); 1059 if (m->has_itable_index()) { 1060 int length = m->itable_index() + 1; 1061 #ifdef ASSERT 1062 while (nof_methods = 0) { 1063 m = methods->at(--nof_methods); 1064 assert(!m->has_itable_index() || m->itable_index() < length, ""); 1065 } 1066 #endif //ASSERT 1067 return length; // return the rightmost itable index, plus one 1068 } 1069 nof_methods -= 1; 1070 } 1071 // no methods have itable indices 1072 return 0; 1073 } 1074 1075 1076 void klassItable::initialize_itable_for_interface(int method_table_offset, KlassHandle interf_h, bool checkconstraints, TRAPS) { 1077 Array<Method*>* methods = InstanceKlass::cast(interf_h())->methods(); 1078 int nof_methods = methods->length(); 1079 HandleMark hm; 1080 assert(nof_methods > 0, "at least one method must exist for interface to be in vtable"); 1081 Handle interface_loader (THREAD, InstanceKlass::cast(interf_h())->class_loader()); 1082 1083 int ime_count = method_count_for_interface(interf_h()); 1084 for (int i = 0; i < nof_methods; i++) { 1085 Method* m = methods->at(i); 1086 methodHandle target; 1087 if (m->has_itable_index()) { 1088 // This search must match the runtime resolution, i.e. selection search for invokeinterface 1089 // to correctly enforce loader constraints for interface method inheritance 1090 LinkResolver::lookup_instance_method_in_klasses(target, _klass, m->name(), m->signature(), CHECK); 1091 } 1092 if (target == NULL || !target->is_public() || target->is_abstract()) { 1093 // Entry does not resolve. Leave it empty for AbstractMethodError. 1094 if (!(target == NULL) && !target->is_public()) { 1095 // Stuff an IllegalAccessError throwing method in there instead. 1096 itableOffsetEntry::method_entry(_klass(), method_table_offset)[m->itable_index()]. 1097 initialize(Universe::throw_illegal_access_error()); 1098 } 1099 } else { 1100 // Entry did resolve, check loader constraints before initializing 1101 // if checkconstraints requested 1102 if (checkconstraints) { 1103 Handle method_holder_loader (THREAD, target->method_holder()->class_loader()); 1104 if (method_holder_loader() != interface_loader()) { 1105 ResourceMark rm(THREAD); 1106 Symbol* failed_type_symbol = 1107 SystemDictionary::check_signature_loaders(m->signature(), 1108 method_holder_loader, 1109 interface_loader, 1110 true, CHECK); 1111 if (failed_type_symbol != NULL) { 1112 const char* msg = "loader constraint violation in interface " 1113 "itable initialization: when resolving method \"%s\" the class" 1114 " loader (instance of %s) of the current class, %s, " 1115 "and the class loader (instance of %s) for interface " 1116 "%s have different Class objects for the type %s " 1117 "used in the signature"; 1118 char* sig = target()->name_and_sig_as_C_string(); 1119 const char* loader1 = SystemDictionary::loader_name(method_holder_loader()); 1120 char* current = _klass->name()->as_C_string(); 1121 const char* loader2 = SystemDictionary::loader_name(interface_loader()); 1122 char* iface = InstanceKlass::cast(interf_h())->name()->as_C_string(); 1123 char* failed_type_name = failed_type_symbol->as_C_string(); 1124 size_t buflen = strlen(msg) + strlen(sig) + strlen(loader1) + 1125 strlen(current) + strlen(loader2) + strlen(iface) + 1126 strlen(failed_type_name); 1127 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1128 jio_snprintf(buf, buflen, msg, sig, loader1, current, loader2, 1129 iface, failed_type_name); 1130 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1131 } 1132 } 1133 } 1134 1135 // ime may have moved during GC so recalculate address 1136 int ime_num = m->itable_index(); 1137 assert(ime_num < ime_count, "oob"); 1138 itableOffsetEntry::method_entry(_klass(), method_table_offset)[ime_num].initialize(target()); 1139 if (TraceItables && Verbose) { 1140 ResourceMark rm(THREAD); 1141 if (target() != NULL) { 1142 char* sig = target()->name_and_sig_as_C_string(); 1143 tty->print("interface: %s, ime_num: %d, target: %s, method_holder: %s ", 1144 interf_h()->internal_name(), ime_num, sig, 1145 target()->method_holder()->internal_name()); 1146 tty->print("target_method flags: "); 1147 target()->access_flags().print_on(tty); 1148 if (target()->is_default_method()) { 1149 tty->print("default "); 1150 } 1151 tty->cr(); 1152 } 1153 } 1154 } 1155 } 1156 } 1157 1158 // Update entry for specific Method* 1159 void klassItable::initialize_with_method(Method* m) { 1160 itableMethodEntry* ime = method_entry(0); 1161 for(int i = 0; i < _size_method_table; i++) { 1162 if (ime->method() == m) { 1163 ime->initialize(m); 1164 } 1165 ime++; 1166 } 1167 } 1168 1169 #if INCLUDE_JVMTI 1170 void klassItable::adjust_method_entries(Method** old_methods, Method** new_methods, 1171 int methods_length, bool * trace_name_printed) { 1172 // search the itable for uses of either obsolete or EMCP methods 1173 for (int j = 0; j < methods_length; j++) { 1174 Method* old_method = old_methods[j]; 1175 Method* new_method = new_methods[j]; 1176 itableMethodEntry* ime = method_entry(0); 1177 1178 // The itable can describe more than one interface and the same 1179 // method signature can be specified by more than one interface. 1180 // This means we have to do an exhaustive search to find all the 1181 // old_method references. 1182 for (int i = 0; i < _size_method_table; i++) { 1183 if (ime->method() == old_method) { 1184 ime->initialize(new_method); 1185 1186 if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) { 1187 if (!(*trace_name_printed)) { 1188 // RC_TRACE_MESG macro has an embedded ResourceMark 1189 RC_TRACE_MESG(("adjust: name=%s", 1190 old_method->method_holder()->external_name())); 1191 *trace_name_printed = true; 1192 } 1193 // RC_TRACE macro has an embedded ResourceMark 1194 RC_TRACE(0x00200000, ("itable method update: %s(%s)", 1195 new_method->name()->as_C_string(), 1196 new_method->signature()->as_C_string())); 1197 } 1198 // cannot 'break' here; see for-loop comment above. 1199 } 1200 ime++; 1201 } 1202 } 1203 } 1204 1205 // an itable should never contain old or obsolete methods 1206 bool klassItable::check_no_old_or_obsolete_entries() { 1207 itableMethodEntry* ime = method_entry(0); 1208 for (int i = 0; i < _size_method_table; i++) { 1209 Method* m = ime->method(); 1210 if (m != NULL && 1211 (NOT_PRODUCT(!m->is_valid() ||) m->is_old() || m->is_obsolete())) { 1212 return false; 1213 } 1214 ime++; 1215 } 1216 return true; 1217 } 1218 1219 void klassItable::dump_itable() { 1220 itableMethodEntry* ime = method_entry(0); 1221 tty->print_cr("itable dump --"); 1222 for (int i = 0; i < _size_method_table; i++) { 1223 Method* m = ime->method(); 1224 if (m != NULL) { 1225 tty->print(" (%5d) ", i); 1226 m->access_flags().print_on(tty); 1227 if (m->is_default_method()) { 1228 tty->print("default "); 1229 } 1230 tty->print(" -- "); 1231 m->print_name(tty); 1232 tty->cr(); 1233 } 1234 ime++; 1235 } 1236 } 1237 #endif // INCLUDE_JVMTI 1238 1239 1240 // Setup 1241 class InterfaceVisiterClosure : public StackObj { 1242 public: 1243 virtual void doit(Klass* intf, int method_count) = 0; 1244 }; 1245 1246 // Visit all interfaces with at least one itable method 1247 void visit_all_interfaces(Array<Klass*>* transitive_intf, InterfaceVisiterClosure *blk) { 1248 // Handle array argument 1249 for(int i = 0; i < transitive_intf->length(); i++) { 1250 Klass* intf = transitive_intf->at(i); 1251 assert(intf->is_interface(), "sanity check"); 1252 1253 // Find no. of itable methods 1254 int method_count = 0; 1255 // method_count = klassItable::method_count_for_interface(intf); 1256 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1257 if (methods->length() > 0) { 1258 for (int i = methods->length(); --i >= 0; ) { 1259 if (interface_method_needs_itable_index(methods->at(i))) { 1260 method_count++; 1261 } 1262 } 1263 } 1264 1265 // Only count interfaces with at least one method 1266 if (method_count > 0) { 1267 blk->doit(intf, method_count); 1268 } 1269 } 1270 } 1271 1272 class CountInterfacesClosure : public InterfaceVisiterClosure { 1273 private: 1274 int _nof_methods; 1275 int _nof_interfaces; 1276 public: 1277 CountInterfacesClosure() { _nof_methods = 0; _nof_interfaces = 0; } 1278 1279 int nof_methods() const { return _nof_methods; } 1280 int nof_interfaces() const { return _nof_interfaces; } 1281 1282 void doit(Klass* intf, int method_count) { _nof_methods += method_count; _nof_interfaces++; } 1283 }; 1284 1285 class SetupItableClosure : public InterfaceVisiterClosure { 1286 private: 1287 itableOffsetEntry* _offset_entry; 1288 itableMethodEntry* _method_entry; 1289 address _klass_begin; 1290 public: 1291 SetupItableClosure(address klass_begin, itableOffsetEntry* offset_entry, itableMethodEntry* method_entry) { 1292 _klass_begin = klass_begin; 1293 _offset_entry = offset_entry; 1294 _method_entry = method_entry; 1295 } 1296 1297 itableMethodEntry* method_entry() const { return _method_entry; } 1298 1299 void doit(Klass* intf, int method_count) { 1300 int offset = ((address)_method_entry) - _klass_begin; 1301 _offset_entry->initialize(intf, offset); 1302 _offset_entry++; 1303 _method_entry += method_count; 1304 } 1305 }; 1306 1307 int klassItable::compute_itable_size(Array<Klass*>* transitive_interfaces) { 1308 // Count no of interfaces and total number of interface methods 1309 CountInterfacesClosure cic; 1310 visit_all_interfaces(transitive_interfaces, &cic); 1311 1312 // There's alway an extra itable entry so we can null-terminate it. 1313 int itable_size = calc_itable_size(cic.nof_interfaces() + 1, cic.nof_methods()); 1314 1315 // Statistics 1316 update_stats(itable_size * HeapWordSize); 1317 1318 return itable_size; 1319 } 1320 1321 1322 // Fill out offset table and interface klasses into the itable space 1323 void klassItable::setup_itable_offset_table(instanceKlassHandle klass) { 1324 if (klass->itable_length() == 0) return; 1325 assert(!klass->is_interface(), "Should have zero length itable"); 1326 1327 // Count no of interfaces and total number of interface methods 1328 CountInterfacesClosure cic; 1329 visit_all_interfaces(klass->transitive_interfaces(), &cic); 1330 int nof_methods = cic.nof_methods(); 1331 int nof_interfaces = cic.nof_interfaces(); 1332 1333 // Add one extra entry so we can null-terminate the table 1334 nof_interfaces++; 1335 1336 assert(compute_itable_size(klass->transitive_interfaces()) == 1337 calc_itable_size(nof_interfaces, nof_methods), 1338 "mismatch calculation of itable size"); 1339 1340 // Fill-out offset table 1341 itableOffsetEntry* ioe = (itableOffsetEntry*)klass->start_of_itable(); 1342 itableMethodEntry* ime = (itableMethodEntry*)(ioe + nof_interfaces); 1343 intptr_t* end = klass->end_of_itable(); 1344 assert((oop*)(ime + nof_methods) <= (oop*)klass->start_of_nonstatic_oop_maps(), "wrong offset calculation (1)"); 1345 assert((oop*)(end) == (oop*)(ime + nof_methods), "wrong offset calculation (2)"); 1346 1347 // Visit all interfaces and initialize itable offset table 1348 SetupItableClosure sic((address)klass(), ioe, ime); 1349 visit_all_interfaces(klass->transitive_interfaces(), &sic); 1350 1351 #ifdef ASSERT 1352 ime = sic.method_entry(); 1353 oop* v = (oop*) klass->end_of_itable(); 1354 assert( (oop*)(ime) == v, "wrong offset calculation (2)"); 1355 #endif 1356 } 1357 1358 1359 // inverse to itable_index 1360 Method* klassItable::method_for_itable_index(Klass* intf, int itable_index) { 1361 assert(InstanceKlass::cast(intf)->is_interface(), "sanity check"); 1362 assert(intf->verify_itable_index(itable_index), ""); 1363 Array<Method*>* methods = InstanceKlass::cast(intf)->methods(); 1364 1365 if (itable_index < 0 || itable_index >= method_count_for_interface(intf)) 1366 return NULL; // help caller defend against bad indices 1367 1368 int index = itable_index; 1369 Method* m = methods->at(index); 1370 int index2 = -1; 1371 while (!m->has_itable_index() || 1372 (index2 = m->itable_index()) != itable_index) { 1373 assert(index2 < itable_index, "monotonic"); 1374 if (++index == methods->length()) 1375 return NULL; 1376 m = methods->at(index); 1377 } 1378 assert(m->itable_index() == itable_index, "correct inverse"); 1379 1380 return m; 1381 } 1382 1383 void klassVtable::verify(outputStream* st, bool forced) { 1384 // make sure table is initialized 1385 if (!Universe::is_fully_initialized()) return; 1386 #ifndef PRODUCT 1387 // avoid redundant verifies 1388 if (!forced && _verify_count == Universe::verify_count()) return; 1389 _verify_count = Universe::verify_count(); 1390 #endif 1391 oop* end_of_obj = (oop*)_klass() + _klass()->size(); 1392 oop* end_of_vtable = (oop *)&table()[_length]; 1393 if (end_of_vtable > end_of_obj) { 1394 fatal(err_msg("klass %s: klass object too short (vtable extends beyond " 1395 "end)", _klass->internal_name())); 1396 } 1397 1398 for (int i = 0; i < _length; i++) table()[i].verify(this, st); 1399 // verify consistency with superKlass vtable 1400 Klass* super = _klass->super(); 1401 if (super != NULL) { 1402 InstanceKlass* sk = InstanceKlass::cast(super); 1403 klassVtable* vt = sk->vtable(); 1404 for (int i = 0; i < vt->length(); i++) { 1405 verify_against(st, vt, i); 1406 } 1407 } 1408 } 1409 1410 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) { 1411 vtableEntry* vte = &vt->table()[index]; 1412 if (vte->method()->name() != table()[index].method()->name() || 1413 vte->method()->signature() != table()[index].method()->signature()) { 1414 fatal("mismatched name/signature of vtable entries"); 1415 } 1416 } 1417 1418 #ifndef PRODUCT 1419 void klassVtable::print() { 1420 ResourceMark rm; 1421 tty->print("klassVtable for klass %s (length %d):\n", _klass->internal_name(), length()); 1422 for (int i = 0; i < length(); i++) { 1423 table()[i].print(); 1424 tty->cr(); 1425 } 1426 } 1427 #endif 1428 1429 void vtableEntry::verify(klassVtable* vt, outputStream* st) { 1430 NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true)); 1431 assert(method() != NULL, "must have set method"); 1432 method()->verify(); 1433 // we sub_type, because it could be a miranda method 1434 if (!vt->klass()->is_subtype_of(method()->method_holder())) { 1435 #ifndef PRODUCT 1436 print(); 1437 #endif 1438 fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this)); 1439 } 1440 } 1441 1442 #ifndef PRODUCT 1443 1444 void vtableEntry::print() { 1445 ResourceMark rm; 1446 tty->print("vtableEntry %s: ", method()->name()->as_C_string()); 1447 if (Verbose) { 1448 tty->print("m %#lx ", (address)method()); 1449 } 1450 } 1451 1452 class VtableStats : AllStatic { 1453 public: 1454 static int no_klasses; // # classes with vtables 1455 static int no_array_klasses; // # array classes 1456 static int no_instance_klasses; // # instanceKlasses 1457 static int sum_of_vtable_len; // total # of vtable entries 1458 static int sum_of_array_vtable_len; // total # of vtable entries in array klasses only 1459 static int fixed; // total fixed overhead in bytes 1460 static int filler; // overhead caused by filler bytes 1461 static int entries; // total bytes consumed by vtable entries 1462 static int array_entries; // total bytes consumed by array vtable entries 1463 1464 static void do_class(Klass* k) { 1465 Klass* kl = k; 1466 klassVtable* vt = kl->vtable(); 1467 if (vt == NULL) return; 1468 no_klasses++; 1469 if (kl->oop_is_instance()) { 1470 no_instance_klasses++; 1471 kl->array_klasses_do(do_class); 1472 } 1473 if (kl->oop_is_array()) { 1474 no_array_klasses++; 1475 sum_of_array_vtable_len += vt->length(); 1476 } 1477 sum_of_vtable_len += vt->length(); 1478 } 1479 1480 static void compute() { 1481 SystemDictionary::classes_do(do_class); 1482 fixed = no_klasses * oopSize; // vtable length 1483 // filler size is a conservative approximation 1484 filler = oopSize * (no_klasses - no_instance_klasses) * (sizeof(InstanceKlass) - sizeof(ArrayKlass) - 1); 1485 entries = sizeof(vtableEntry) * sum_of_vtable_len; 1486 array_entries = sizeof(vtableEntry) * sum_of_array_vtable_len; 1487 } 1488 }; 1489 1490 int VtableStats::no_klasses = 0; 1491 int VtableStats::no_array_klasses = 0; 1492 int VtableStats::no_instance_klasses = 0; 1493 int VtableStats::sum_of_vtable_len = 0; 1494 int VtableStats::sum_of_array_vtable_len = 0; 1495 int VtableStats::fixed = 0; 1496 int VtableStats::filler = 0; 1497 int VtableStats::entries = 0; 1498 int VtableStats::array_entries = 0; 1499 1500 void klassVtable::print_statistics() { 1501 ResourceMark rm; 1502 HandleMark hm; 1503 VtableStats::compute(); 1504 tty->print_cr("vtable statistics:"); 1505 tty->print_cr("%6d classes (%d instance, %d array)", VtableStats::no_klasses, VtableStats::no_instance_klasses, VtableStats::no_array_klasses); 1506 int total = VtableStats::fixed + VtableStats::filler + VtableStats::entries; 1507 tty->print_cr("%6d bytes fixed overhead (refs + vtable object header)", VtableStats::fixed); 1508 tty->print_cr("%6d bytes filler overhead", VtableStats::filler); 1509 tty->print_cr("%6d bytes for vtable entries (%d for arrays)", VtableStats::entries, VtableStats::array_entries); 1510 tty->print_cr("%6d bytes total", total); 1511 } 1512 1513 int klassItable::_total_classes; // Total no. of classes with itables 1514 long klassItable::_total_size; // Total no. of bytes used for itables 1515 1516 void klassItable::print_statistics() { 1517 tty->print_cr("itable statistics:"); 1518 tty->print_cr("%6d classes with itables", _total_classes); 1519 tty->print_cr("%6d K uses for itables (average by class: %d bytes)", _total_size / K, _total_size / _total_classes); 1520 } 1521 1522 #endif // PRODUCT